key: cord- -p q t se authors: burghardt, keith; lerman, kristina title: unequal impact and spatial aggregation distort covid- growth rates date: - - journal: nan doi: nan sha: doc_id: cord_uid: p q t se the covid- pandemic has emerged as a global public health crisis. to make decisions about mitigation strategies and to understand the disease dynamics, policy makers and epidemiologists must know how the disease is spreading in their communities. we analyze confirmed infections and deaths over multiple geographic scales to show that covid- 's impact is highly unequal: many subregions have nearly zero infections, and others are hot spots. we attribute the effect to a reed-hughes-like mechanism in which disease arrives at different times and grows exponentially. hot spots, however, appear to grow faster than neighboring subregions and dominate spatially aggregated statistics, thereby amplifying growth rates. the staggered spread of covid- can also make aggregated growth rates appear higher even when subregions grow at the same rate. public policy, economic analysis and epidemic modeling need to account for potential distortions introduced by spatial aggregation. the covid- pandemic has spread rapidly around the globe, claiming hundreds of thousands of lives and wreaking havoc on world economies. public health experts and policy makers must consider a complex array of metrics when deciding when and how to enforce mitigation strategies, such as closing schools and businesses. an important consideration in these calculations is a measure of how quickly the virus is spreading within the communities: a fast spreading virus may force municipalities, states and nations to order residents to shelter at home to slow transmission. epidemiologists must similarly measure the growth rate to better understand the underlying mechanism of the disease, including its basic reproduction number ( ), or to forecast its spread ( ). using confirmed infections and deaths data from a variety of sources around u.s. and the world, we show that the impact of covid- is highly unequal, with hot spots emerging at multiple spatial scales ( ): from individual facilities ( ) and city neighborhoods ( ) , to u.s. counties and states ( ) , to nations ( ) . we also show that spatial aggregation of covid- data leads to higher growth rates than within most subregions, which we call aggregation bias. as a result, growth rate at a city-level overestimates how quickly the disease spreads through city neighborhoods, and state-level growth rates are higher than for most counties within each state. we argue that hot spots and aggregation bias arise because disease appears in new subregions at different times and grows at different rates. as a result, subregions where the disease is spreading more quickly grow to become hot spots and dominate statistics. spatial aggregation of data over the subregions produces growth estimates that are systematically higher relative to growth rates within most subregions. more interestingly, because disease arrives in subregions at different times, spatial aggregation can also exaggerate the growth rate even when disease is spreading at the same rate within the subregions. to better understand aggregation bias, we create a simple stochastic model that is variant of a reed-hughes mechanism ( ), with synthetic communities in which the disease arrives at different times and grows at different rates. both the arrival times and growth rates are picked from empirical distributions. we show that the varying ages of outbreaks create a heavy-tailed distribution of the number of infections and deaths, with a small number of hot spots representing the majority of all infections and deaths. the size of the outbreak is highly correlated with the growth rate in the subregion; therefore, when the synthetic data is aggregated to simulate state or national statistics, these hot spots systematically amplify the estimated growth rates, much like what is observed empirically. in addition, even when growth rates are the same, the staggered arrival of the virus in communities amplifies the growth rates in aggregated data. epidemic modeling and public health policy need to account for the role biases play in data aggregation. when calculating the costs and benefits of lock-downs, for example, analysts must control for these biases to better understand the risks people face. aggregate data could also affect parameters in epidemic models and therefore reduce model prediction accuracy. figure demonstrates the unequal impact of covid- in the u.s. and the world. the number of deaths in u.s. counties and states has a heavy-tailed distribution (fig. a ). this means that the disease's toll varies enormously between places, with many communities almost unaffected and others hit hard by the pandemic. for example, new york city accounts for the bulk of all deaths in new york state, which accounts for a large fraction of all u.s. covid- deaths. the number of infections has a heavy-tailed distribution across multiple spatial scales (fig. b) : from large outbreaks at u.s. facilities (e.g., nursing homes, prisons and meat packing plants) catalogued by the new york times, to los angeles and new york city neighborhoods, u.s. counties and states, and world nations. despite differences in the availability of testing, there exist strong regularities in the prevalence of outbreaks at these vastly disparate spatial scales. how does this large variation arise? figure c shows the growing toll of the disease in new york state and its ten hardest-hit counties. the growth in the number of deaths within each figure : inequality of covid- impact and spatial aggregation bias. (a) the number of deaths has a heavy-tailed distribution for both states and counties, with the most cases in new york state and new york city, respectively. a stochastic model discussed in the main text captures the properties of the distribution. (b) similar pattern is seen for infections at many spatial scales: from u.s. facilities to neighborhoods to nations. (c) deaths over time for new york and some of its counties, where we see the disease arrives in counties at different times, but the initial growth rate is approximately exponential. exponential growth is calculated between day and (inclusive) for new york state; the time window varies for each county. (d) the death growth rate in the u.s. is higher than most states, which is in turn higher on than growth rates in individual counties. inset: this finding is also captured by the simulation. findings are qualitatively similar in data of infections (see supplementary figure ). county (and state) in the early stages of the outbreak can be roughly modeled by an exponential, which allows us to estimate the average growth rate (agreement with exponential fits has been checked in supplementary figure ). there is a fairly broad distribution of death rates for counties and states (fig. d ). however, this by itself is not enough to explain the heterogeneity in the number of cases or deaths. we must also consider that covid- appears in each subregions at different times. this phenomenon is closely related to the reed-hughes mechanism ( ), which explains how exponentially growing populations of different ages produce a power-law distribution of population sizes. however, the reed-hughes mechanism specifies that populations have the same growth rate and begin growing with uniform probability in time. in contrast, the start time of the outbreak in each county is approximately normally distributed, as is the growth rate. to validate the modified mechanism, we create synthetic data in which simulated counties have outbreaks that start at times drawn at random from a normal distribution, with growth rates chosen from another normal distribution and coefficients of growth rates drawn from a log-normal distribution. all distribution parameters are empirically measured from fits to data, except arrival times that are gathered directly from data. synthetic outbreaks within our simulated counties follow a heavy-tailed distribution (blue line in fig. a ) similar to the empirical distribution for counties. the situation is somewhat more complex for states. simply dividing counties across states at random, so that each simulated state ends up aggregating data over counties (this is the mean number of counties in a state), creates a very sharply-peaked distribution, unlike what we observe. instead, we divide up counties non-uniformly across states such that the number of counties in these simulated states matches the true distribution. this re-creates the heavy-tailed distribution of the number of deaths for states (orange line in fig. a) . these results demonstrate that large heterogeneity in the data creates a qualitatively similar outcome as the reed-hughes mechanism. these deviations from the traditional reed-hughes mechanism can also create aggregation bias. the hot spots dominate the statistics and are correlated with faster growing infections ( fig. and ) . this makes deaths and infections appear to grow faster when spatially aggregated, such as aggregating data from counties to the state level. similarly, the growth rate at the national level appears to be higher than death rates within constituent states and counties (fig. d) . aggregation bias is also observed in simulated data with synthetic counties and states ( fig. d inset and a inset) . alike to what we observe empirically, we find spearman correlations of . between growth rates and simulated number of deaths or growth rates and simulated numbers of infections (p-values < − ). to better understand why, we make a simulation where infections grow with the same exponential growth rate (∼ . t or . % a day), and the arrival time of the infection in each neighborhood matches la data. in this idealized simulation, each neighborhood's growth rate can be easily fit to an exponential, but the aggregate fails to follow an exponential. a reasonable fit significantly over-shoots the growth rate of each neighborhood. aggregation bias can also arise when combining data from communities with similar growth rates. our analysis of comprehensive covid- data from cities and neighborhoods within los angeles county (fig. ) shows that while the average growth rates in the number of infections within neighborhoods is similar to each other (fig. a) , they are substantially lower than the growth rate for los angeles county as a whole (fig. b) . the difference arises from the staggered arrival of the disease in different neighborhoods. to validate this, we simulated neighborhoods with the same growth rate of ∼ . t , with arrival times taken directly from the los angeles neighborhoods. even though each simulated neighborhood has the same growth rate, their staggered arrival times lead to a higher aggregate growth rate. the systematic overestimation of aggregated growth rates is an example of modifiable areal unit problem ( ), a statistical bias similar to simpson's paradox ( ) , that results in varying statistical trends at different levels of aggregation of heterogeneous data. interestingly, the only scale we do not see aggregation bias is the global scale. infections growth rate for the world as a whole is comparable to most countries (fig. ). this is, however, because the growth is initially dominated by just one country, china. the initial world growth rate is correlated to the first, rather than the fastest growing, country. lastly, we explore why growth rates vary. we find that growth rates are correlated with population and population density (see figs. and ): covid- spreads more quickly in large and dense counties, states and nations. population density appears to play a somewhat more important role in explaining death growth rates for states. however, this is not the case for infections, where population, rather than population density, better explains the growth of infections across multiple spatial scales (fig. c ), in agreement with trends for cities reported by ( ) . while it seems intuitive that denser places with more interpersonal interaction are at a greater risk for spreading the disease, this may not be the entire explanation. instead, it appears that the total number of people is an important driver. in addition, communities where the disease arrived earlier also tend to have higher growth rates, possibly because it was allowed to spread before mitigation measures were introduced. covid- 's toll around the world varies widely, with many regions seeing few deaths and confirmed cases, while a handful of regions are greatly affected. the heavy-tailed distribution of impact has important implications for decision makers. first, local hot spots, where the virus is far more prevalent than elsewhere, are typically the more vulnerable communities with large populations. these hot spots bias aggregated growth rates covid- statistics, making the disease appear to grow faster at a larger scale than it does within the constituent communities. however, we show that spatial aggregation could potentially inflate growth rates due to the staggered arrival of the virus in the communities even when growth rates in subregions are the same. as a result, aggregating data at a larger scale, e.g., state or national level, will make the disease appear to grow faster than it does within the constituent regions. analysis of the effects of interventions, including lock downs and other mitigation strategies, has to account for potential biases introduced by data aggregation. local hot spots and staggered arrival of infections may effectively amplify the rates of the disease for some regions (e.g., states and countries), obscuring the benefits of early interventions. from the modeling perspective, since epidemic statistics are driven by a few hot spots (typically large, dense cities or facilities), compartmental models ( ) may be more effective for modeling the disease. the assumptions made by compartmental models, namely uniform mixing of populations, are best aligned with mobility patterns in cities ( ) and facilities that regularly bring people in contact with one another. compartmental models typically have fewer fitting parameters than spatio-temporal models ( ) ( ) ( ) , and therefore, may be better at making intermediate-range forecasts ( ). that being said, such models may produce poorer predictions due to staggered disease arrivals that spatio-temporal models can better control for. future work is needed to understand how these results generalize to other diseases. for example, it is important to test the reed-hughes-like statistical model to other diseases and countries to see the degree to which it can help explain infection hot spots. we do, however, observe some ways in which our findings differ from other diseases. for example, the growth rate of ebola is negatively correlated with population density ( ) , potentially due to lack of healthcare infrastructure. but this may a special case, due to the impoverished countries that were infected. data on cumulative covid- infections is obtained from the new york times ( ) areas where deaths appeared earlier also tend to have higher growth rate. whatever the reason for the growth rate, faster growing areas have many more cases than slower-growing areas. similar results hold for infections as well (fig. ) . infections (deaths) are removed to reduce effects of outliers. the threshold is three for los angeles neighborhood data because agreement with exponential is reasonable even when we start with this lower threshold. over time the data deviates from exponential growth. we consider the data to deviate significantly if we have more than two consecutive days of growth below . %. those two days, and all subsequent data, is removed from analysis. a more stringent threshold of . % growth over three days produces very similar results. in addition, we only fit data with more than five datapoints. calculations of r are based on this log-scaling of data. we observe the infection growth rate of the u.s. is higher than most states, which is, in turn, higher than most counties. (b) we find population correlates strongly with growth rate from neighborhoods in la to countries, but population density is less important. the time since the first infection is weakly correlated with the growth rate. whatever the reason for the growth rate, we find the number of infections strongly correlates with the growth rate, therefore fast-growing areas dominate the statistics. examples of growth rates versus (c) population and (d) population density. compare to fig. and in the main text. . surprisingly, the world as a whole has a growth rate comparable to most countries, most likely because the growth rate is initially dominated by just one country, china, therefore the world growth is dominated by the first, rather than the fastest growing, country. los angeles county this work was funded in part by darpa under contract hr . key: cord- -o mwd d authors: tam, ka-ming; walker, nicholas; moreno, juana title: projected development of covid- in louisiana date: - - journal: nan doi: nan sha: doc_id: cord_uid: o mwd d at the time of writing, louisiana has the third highest covid- infection per capita in the united states. the state government issued a stay-at-home order effective march rd. we analyze the projected spread of covid- in louisiana without including the effects of the stay-at-home order. we predict that a large fraction of the state population would be infected without the mitigation efforts, and would certainly overwhelm the capacity of louisiana health care system. we further predict the outcomes with different degrees of reduction in the infection rate. more than % of reduction is required to cap the number of infected to under one million. the identification and verification of human-to-human transmission of the coronavirus disease in early january of in wuhan, china triggered the start of a worldwide pandemic. as of april , there are more than . million confirmed cases and more than , deaths attributed to covid- . the first case in the us was confirmed in washington state on january . the number of reported cases until early march was rather low. the exceedingly slow spreading rate in these early months may be partially due to the lack of adequate testing, which remains a major issue at the time of writing. the cases dramatically increased in the usa in early march, with most cases in the states of washington, new york, and california. it was not until march that the first case in louisiana was identified. the growth rate of infections in louisiana has been alarming since the confirmation of the first case. louisiana state government responded swiftly by closing all k- public schools on march . on march , public gatherings of more than people were prohibited, and bars, bowling alleys, casinos, fitness facilities, and movie theaters were closed. furthermore, a stay-at-home order was issued on march . adequate testing for covid- remains limited in the usa. for this reason, accurately predicting the trajectory of the spread of covid- by relying on the number of confirmed cases alone is a rather questionable approach. while the susceptible-infected-recovered (sir) model may well describe the dynamics of the spreading , , accurate predictions rely on knowing the number of confirmed cases, which is severely hampered by the limitations of testing. this is particular significant in the early stages of the spread of the disease when the percentage of people tested is very small, and the spread by infected people who are asymptomatic is very significant. alternatively, the number of fatalities attributed to covid- may be a more reliable parameter for tracing the dynamics of the virus spread. combining this information with the mortality rate can be a better strategy to predict the number of cases than relying on the con-firmed infection count alone. the goal of this paper is to extract the dynamics of covid- in louisiana from the data of the death count supplemented with the confirmed cases. we then run several scenarios with different reduction of the infection rate and calculate the number of people infected in each case. we conclude with suggestions to improve the model and, as consequence, its predictions. our model is based on the susceptible-infected-recovered (sir) model with the modification of including the number of quarantined people (q), as has been considered elsewhere. [ ] [ ] [ ] the equations defining the model are the following: where n is the total population size, s is the susceptible population count, i is the unidentified infected population count, q is the number of identified cases, and r includes the number of recovered and dead patients. the model is characterized by the following parameters: β is the infection rate, η is the detection rate, α is the recovery rate of asymptomatic people, and γ includes the recovery rate and the casualty rate of the quarantined patients. this model is equivalent to the standard sir model if we are not interested into differentiating between q and r. we further assume that the rate of increase in the number of casualties is proportional to the number of infected at the early stage of the epidemic, where δ is the mortality rate. this is a good approximation at the beginning of the virus spread when the number of quarantined patients is a small percentage of the total population. this equation is not combined in any way with eq. - , it is only used to estimate the model parameters at the start of the epidemic. we first consider eq. , assuming the susceptible population count is very close to that of the total population, s ∼ n , which is justifiable at the beginning of the epidemic since only a small fraction of the population is infected. with this assumption one can decouple the infected population count from the other parameters to obtain: , solving eq. , the casualty count as a function of time can be written as the exponential growth of the number of fatalities at the beginning of the epidemic should represent the spreading of covid- reasonably well since the mechanisms for slowing the dynamics, such as improved detection and social distancing, are delayed in time by fitting the available fatalities data (see appendix) between march and to eq. , the parameters of the model can be determined. fig. displays the fit which provides an estimate of c(t) ≈ . exp [ . t]. the dynamics (exponent) is thus given as β − (α +η) = . . from the value of the exponent we can estimate the time for doubling the casualties count: ln( )/ . ≈ . days. moreover, the proportionality constant can be used to estimate the initial number of infections i( ) if the mortality rate δ is known. the mortality rate is estimated by combining the accumulated mortality rate data and the median time between infection and death. it is estimated that the median time between infection and the onset of symptoms is about five days, while the median time between the onset of symptoms and death is eight days. [ ] [ ] [ ] [ ] it is worth noting that the distribution of these time periods is close to a log-normal, thus a more sophisticated analysis should include the effects of the non-self-averaging behavior of the distribution. only the median values are used in the present work. the parameters of eq. are fit to the data, providing an approximation to the number of deaths as a function of time: the accumulated mortality rate is estimated to be . % . notably, the mortality rate does indeed vary by region. this may be due to the rate of testing as well as the capacity of health care facilities. for areas in which health care facilities have been overrun, the death rate would be much higher. notwithstanding these uncertainties, assuming that the health care facilities have not yet been overrun, the mortality rate is estimated to be δ ≈ . + ≈ . . this also provides an estimation of the number of persons who carries the virus but not detected at day , i( ), which is given as i( ) ≈ . δ × . ≈ . this reveals that even as early as march , the number of infected people is already at the order of hundreds. now we consider the number of confirmed cases at the start of the epidemic, p (t). this is given by the sum of q(t) and r(t) subtracted by the number of persons who recovered without being tested. the rate of change on the number of reported cases can be obtained by combining eqs. and and subtracting αi(t): with i(t) given by eq. , we obtain: , by fitting the number of confirmed cases (fig. η ≈ × . ≈ . . there remains one parameter to be determined, the recovery rate of asymptomatic people, α. assuming that the average time or recovery or dead are both days, and half of the infected never show any symptoms thus they are not been tested . we can estimate α = . / ≈ . . this is probably the upper bound of the estimate, in reality this could be smaller. this additionally provides the value for β as . . with these parameters, eqs. - can be solved and used to predict the spread of the disease. fig. displays the time evolution of the number of unidentified persons who carry the virus, i(t), the number of persons who are either in quarantine or recovered, q(t) + r(t), and the total number of persons who have ever been infected, q(t)+r(t)+i(t). the number of infections but unidentified, i(t), grows exponentially, as expected from eq. , at the initial stage, and this behavior continues until about day , when around , people are infectious. the exponent of ∼ . suggests the number of cases double approximately every three days, which seems to be consistent with the data in many areas of the world before the mitigation efforts are kicked in. after day , the rate of increase slow down due to the combination of the decrease on the number of susceptible (uninfected) people and the increase on the number of recoveries. the number of infected cases ceases to grow exponentially, but rather becomes a stable but constant increases until peaking at around day , corresponding to early may. on the other hand, the number of quarantined and recovered people resembles a logistic function. to compare with other states which already have widespread epidemic, we use the described method to calculate the infection rate (β), the testing rate (η), and the reproduction number (r = β/(η + α)) of selected states. result are displayed in table i . note than the reproduction number of louisiana is the highest among the states listed in the table. within the present model, there are two major routes to slow the initial exponential growth of the epidemic, which is characterized by the parameter β − (α + η). the first one is to decrease the infection rate, β. the second route is to increase the testing rate, η. to increase the recovery rate from unidentified persons, α, can also reduce the spread, but it is unlikely to be achieved. as the stay-at-home order was issued on march , it is expected that the infection rate should be drastically reduced. we simulate new scenarios with the assumption that social contact is reduced so that the infection rate decreases by fig. : the number of people who are infected and carrying the virus without being identified, i(t), as a function of time, with march as day . we assume the mitigation efforts reduce the infection rate by %, %, %, %, and % from day ( days after the stay-at-home order), and the sum of the testing rate and recovery rate of asymptomatic people remains unchanged. the inset is a zoom for the first days. %, %, %, %, and % starting at day . the results are shown in fig. and . we find that there is a substantial drop of the active virus carriers even with a % reduction in the infection rate. however, the number of people who will be infected still exceeds one million if the reduction in the infection rate is smaller than %. this suggests the importance of strict measures in social distancing. perhaps it also suggests the importance of wearing basic protective gear to further reduce the infection rate. there are many uncertainties in this simplified model which can be improved over time as more data become available. improvement can be achieved by including additional factors, such as correlation with different age groups, correlation with the health condition of the population, the availability of public health care, the effect of higher ambient temperature and humidity, and many others. some of those factors are likely beyond the sir model which implicitly assume that the population is homogeneous and well mixed, and that infection occurs without time delay. however, given the rather limited data available today, it is not clear that more sophisticated models may provide much better predictions. in spite of the rather simple model being employed in this analysis, it provides a baseline for the spread of the covid- in louisiana in the absence of mitigation efforts. the situation is clearly dire, as a very large fraction of the population will get infected with a peak on the number of infections around early may. with the current mitigation efforts, we expect the infection rate will be greatly reduced. currently, we do not have data to support the effectiveness of current mitigation efforts as the trend still fits rather well to the initial stage of exponential growth. the main projection from this work is that more than % of reduction in the infection rate is needed to keep the infected count below one million. increasing testing capacity and providing protective gear to further reduce the infection rate seem to be reasonable measures. the covid irccs san matteo pavia task force coronavirus disease (covid ) situation report- key: cord- -yhb m si authors: abdulah, deldar morad; hassan, a. b. title: relation of dietary factors with infection and mortality rates of covid- across the world date: - - journal: j nutr health aging doi: . /s - - - sha: doc_id: cord_uid: yhb m si objective: poor dietary habits are considered to be the second-leading risk factors for mortality and disability-adjusted life-years (dalys) in the world. dietary patterns are different based on cultural, environmental, technological, and economic factors. nutritional deficiencies of energy, protein, and specific micronutrients have been shown to contribute to depressed immune function and increased susceptibility to infections. we aimed to explore the relation of dietary factors with global infection and mortality rates of covid- in this study. design: in the current ecological study, the countries that had national dietary data from the global dietary databases of the united nations and coronavirus disease statistics from the world health organization (who) were included. the countries that had coronavirus disease statistics from the who were consecutively checked for the recent data of the dietary factors. setting: world. participants: countries across the world. measurements: infection and mortality rates of covid- ; dietary factors. results: the median crude infection and mortality rates by covid- were . (iqr: . ) and . (iqr: . ), respectively. the two highest percentage of the crude infection rate were between and ( . %) and – ( . %) per one million persons. the regression analysis showed that the crude infection rate has been increased by raising consuming fruits (beta: . ; p= . ) and calcium (beta: . ; p= . ) and was decreased with rising consuming beans and legumes (beta: − . ; p= . ). the analysis showed that the crude mortality rate was increased by raising consuming sugar-sweetened beverages (beta: . ; p< . ). whereas, the crude mortality rate by covid- has been decreased by increasing fruits consuming (beta: − . ; p= . ) and beans and legumes (beta: − . ; p= . ). conclusion: the present study showed the higher intake of fruits and sugar-sweetened beverages had a positive effect on infection and mortally rates by covid- , respectively. in contrast, the higher intake of beans and legumes had a negative effect on both increasing infection and mortality rates. poor dietary habits are considered to be the second-leading risk factors for mortality and disability-adjusted life-years (dalys) in the world. the poor dietary habits are responsible for . million deaths and . million dalys in ( ) . for example, the following dietary habits are among the leading risk factors for early death and disability in european countries. the habits are low intakes of whole grains, fruit and vegetables, and nuts and seeds, and high intakes of alcohol and sodium. the western dietary habits are consuming diet processed, high in red and processed meat, diets with high in sugar-sweetened beverages, and low in milk. these kinds of dietary habits are regarded to be a rising health concern. dietary patterns are different based on cultural, environmental, technological, and economic factors. however, the dietary patterns are becoming similar due to increasing living standards and growing globalization of the food sector ( , ) . mertens et al. ( ) explored the dietary intakes in four different european counters using individual-level dietary intake in adults in nationally-representative surveys of denmark, france, czech republic, and italy. they reported a higher intake of fruits and vegetables and lower intakes of sweetened beverages and alcohol in italy. while individuals in denmark and the czech republic had a higher intake of vegetables. a comparison of population subgroups within countries shows that there is a difference in the dietary preferences, beliefs, and practices for particular consumer groups. for example, highly-educated persons and women have a higher intake of fish, nuts, and seeds along with lower intake of red and processed meats ( ) . the individual-level reported dietary data of the countries could be used as a useful tool to make a connection between health and environment with foods as their common denominator ( ) . a recent review study reported that the detailed assessment of patients for the dietary and nutritional risks along with medical, lifestyle, and environmental factors with suitable risk management strategies make the sensible way to deal with the covid- ( ) . the diet and nutrition have a variance impact on the immune system competence. in addition, they determine the risk and severity of the infections. the relation between diet, nutrition, infection, and immunity is bidirectional ( ) . the macro-, micronutrients, and phytonutrients in diet, such as fruits and colorful vegetables improve healthy immune responses. the microand phytonutrients provide the antioxidants and the antiinflammatory nutrients, like beta-carotene, vitamin c, vitamin e, and polyphenolic compounds resulting in modulating the immune functions ( , ) . nutritional deficiencies of energy, protein, and specific micronutrients have been shown to contribute to depressed immune function and increased susceptibility to infections. the sufficient intake of iron, zinc, and vitamins a, e, b , and b is vital for the overall maintenance of immune function ( ) . the new epidemics of coronavirus disease (covid- ) has become a pandemic to the world currently. we make a hypothesis that geographical variation in dietary factors could have a role in infection and mortality rates of covid- in the world. therefore, we aimed to explore the relation of dietary factors with global infection and mortality rates of covis- in this study. in the current ecological study, the countries that had national dietary data from the global dietary databases of the united nations ( ) and coronavirus disease statistics from the world health organization (who) were included ( ) . the countries that had coronavirus disease statistics from the who were consecutively checked for the recent data of the dietary factors. the countries/states met eligibility criteria for this investigation if they had the statistics from the who coronavirus disease (covid- ) situation dashboard from the website of the world health organization by april ( ) . the following countries were excluded from the analysis due to not having the statistics of the covid- ; comoros, north korea, kiribati, lesotho, malawi, marshall islands, micronesia, nauru, palau, samoa, sao tome, and principe, solomon islands, south sudan, tajikistan, tonga, turkmenistan, tuvalu, vanuatu, and yemen. the following countries were excluded from the study due to not having data on the national dietary factors on the website of the global dietary database ( ) the populations of the countries were extracted from the united nations statistics division ( ) . the estimated populations of the year were considered for the countries. some of the countries had not the population for the year . therefore, the authors checked for the years , , and . accordingly, the population of was used for the following country; algeria. the population of was considered for the following countries: lybia; sierra leone. the population of was extracted for the following countries: mali; mauritania; papua new guinea; sudan and for the following countries; bhutan; bosni; burkina faso; fiji; guyana; niger; nigeria; pakistan; uae. the populations of the following countries were not available for the - period. therefore, the population of the following countries was not included in this study based on the eligibility criteria. these countries were the central african republic; djibouti; djibouti; dominica; gabon; kosovo; lebanon; liberia; moldova; russia; saint kitts and nevis; syria; somalia, the democratic republic of the cong. finally, countries/states were included in this study. the general characteristics of the countries were presented in median (interquartile range [iqr], mean (std. deviation), and number (percentage). the confirmed and dead cases were presented in median and interquartile range due to the nonnormal distribution of the data. the normality of the outcomes was examined in drawing a histogram and box plot. the number of confirmed cases was divided by the total population of a country multiplied by , to obtain the infection rate of covid- per one million persons. the number of dead cases was divided by the total number of confirmed cases and divided by total population multiplied by , to obtain the mortality rate/ , persons.. the infection and mortality rates were determined in a median and interquartile range following dealing with the potential outliers. the upper limit values were considered for the extremely higher limit values in the infection and mortality rates. the crude infection rate was categorized into the following groups; - ; - ; - ; - ; - ; and > per one million person. the infection and mortality rates were transformed through the ln technique to obtain a normally distributed histogram. no ethical aspect was applicable to this study. the median crude infection rate by covid- was . (iqr: . ) ranged between . and . per , persons. the median mortality rate by covid- was . (iqr: . ) ranged between . and . per , persons. the two highest percentage of the crude infection rate were between and ( . %) and - ( . %) per one million persons ( table ) . the study showed the crude infection rate was raised with increasing consuming fruits (r= . ; p< . ), unprocessed red meats (r= . ; p< . ), fruit juices (r= . ; p< . ), total protein (r= . ; p< . ), calcium (r= . ; p< . ), potassium (r= . , p< . ), and total milk (r= . ; p< . ). regarding crude mortality rate per , persons; the study showed that crude mortality rate was raised with increasing consuming unprocessed red meats (r= . ; p= . ), sugar sweetened beverages (r= . ; p= . ), fruit juices (r= . ; p= . ), calcium (r= . ; p= . ), and total milk (r= . ; p= . ). however, the mortality rate was decreased following increasing consuming non-starchy vegetables (r=- . ; p= . ), see table . the regression analysis showed that the crude infection rate has been increased by raising consuming fruits (beta: . ; p= . ) and calcium (beta: . ; p= . ). however, the infection rate was decreased with rising consuming beans and legumes (beta: - . ; p= . ), table . the effect of dietary factors on the crude mortality rate by covid- was examined in the regression analysis. the analysis showed that the crude mortality rate was increased by raising consuming sugar-sweetened beverages (beta: . ; p< . ). whereas, the crude mortality rate by covid- has been decreased by increasing fruits consuming (beta: - . ; p= . ) and beans and legumes (beta: - . ; p= . ), as presented in table . the comparison of dietary factors in countries with different infection rates was examined in table and fig . the study showed that the countries with higher infection rates between and above had a higher intake of fruits (p= . ), fruit juices (p< . ), calcium (p< . ), potassium (p< . ), and total milk (p< . ). however, these countries had a lower intake of unprocessed red meats (p< . ) and total protein (p= . ). the aim of the food-based dietary guidelines is to maintain the general health of the population and prevent non-communicable diseases ( ) . most of the food-based dietary guidelines recommend intake of whole grains, fruit and vegetables, low-fat dairy and fish, and low intake of red and processed meat, sugar-sweetened food products, alcohol, and salt ( ) . the present study showed that the crude infection rate by covid- has been increased by raising consuming fruits, calcium and decreased with increasing consuming beans and legumes. regarding the mortality rate, the analysis showed that the crude mortality rate was increased by raising consuming sugar-sweetened beverages and decreased by increasing fruits consuming and beans and legumes. the anti-inflammatory strategies inside foods, nutrients, or ( , ) since the coronavirus has serious inflammatory consequences for acute pneumonia in persons ( ) . the human coronavirus infections cause mild to severe diseases, systemic inflammation, high fever, cough, and acute respiratory tract infection and dysfunction in internal organs leading to death. this virus is classified as a ribonucleic acid (rna) virus. the virus has a genome that often escapes the innate immune system, particularly if it is malfunctioning ( ) . entering coronavirus into the organism activates innate immunity, which intervenes in the first instance to engulf the invader. the severity of the diseases locates within the ability of innate immune cells to stem viral infection ( ) . the virus has less ability to replicate itself and induce the pathological state in the case of the stronger innate immune system. when the immune system is suppressed by the virus, the body activates the adaptive immunity. the coronavirus enables to produce viral enzymes and proteases. these enzymes and proteases can damage the immunity and inhibit the signaling pathways of type i interferon (ifn) along with the nuclear factor-κb, facilitating innate immune evasion ( ) . apart from the age-related micronutrient inadequacy, the nutritional status of a person has a role in the developing risk of sars-cov-ii infection, the clinical course, and the disease outcomes. hence, the maintenance of host macro-and micronutrient status is considered to be a crucial preventive measure for covid- ( ) . the coronavirus infection is primarily attacked by immune cells, however, the virus has developed viral proteins overtime that counteracts with the innate immune system ( ) . some of the viral proteins antagonize interferon (inf) and stimulate inflammatory proteins, such as il- family member cytokines ( ) . the inflammatory state and pathogenesis of the disease are escalated after abnormal production of cytokines as shown in sars ( ) . our hypothesis is that the higher intake of fruits makes the persons at further risk of infection by the covid- . despite fruits and vegetables have anti-inflammatory and antioxidant factors and have an important role in enhancing the immune system responses ( ) . but higher intake of these micronutrients makes a barrier in improving the human immune system or response to the pathogens due to the role of the fruits with a high glycemic index. our study showed that beans and legumes have a positive role in reducing the infection rate by the covid- . the human body requires the substates in the plant proteins to improve or respond to the vial pathogens because of the human body unable to produce these substrates ( ) . therefore, the body needs these substates to protect the organs against the coronavirus. we assume that the immune body system unable to recognize the virus at the early times. comparison of dietary factors in countries with different infection rates therefore, the available proteins are essential for the body to make a response to the pathogen. the beans and legumes have been effective to reduce the rate of mortality by the covid- as well. the role of age in the suppression of the immune system must not be overlooked. the population of the countries with a higher infection rate is older compared to the counters with a low infection rate ( ) . for example, france and italy compared to iraq and saudi arabia. the available evidence indicates that adults aged years and older and patients with preexisting medical conditions are more likely to have sever-even deadly-coronavirus infection that other population groups ( ) . therefore, we can make the further hypothesis that the aged population of the countries with high infection rates has been the main factor in the low immune system. the impacts of aging on the immune system can reflect at multiple levels. the levels are decreased production of b and t cells in bone marrow and thymus and diminished functions of mature lymphocytes in secondary lymphoid tissues. so, the elderly persons do not respond to immune challenges as robustly as the young individual ( ) . the higher intake of fruits and vegetables may not be beneficial to enhance the immune system in aged populations. diet alone may be insufficient and tailored micronutrient supplementation based on specific age-related needs necessary ( ) . many micronutrients are required for immune-competence, especially vitamin a, c, d, e, bs, iron, selenium, and zinc. moreover, the dietary pattern is essential to maintain the nutritional status of an individual. however, the diet alone could not be adequate in certain metabolic and lifestyle conditions, such as elderlies, co-existing medical conditions, cigarette smoking, or occupational exposure to environmental toxins ( ) . the fruits have several vitamins and minerals. the fruits at a ground level may not be quite suitable to make the final judgment. the older persons over the age of - experience some immune dysregulation with less ability to respond to immune challenges and response to pathogens, antigens, and mitogens decreases ( ) . the decrease in the number of circulating lymphocytes and loss of immune cells are characteristics of the immune system in older people ( ) . moreover, the older peoples have reduced the production of t cells in the involved thymus and consequently diminished function of mature lymphocytes in secondary lymphoid tissues ( ) . the lifetime of exposure to antigens and to several sources of oxidative stress cause dysregulation in the immune system that makes them at further risk of infections than other age groups ( ) . the role of fruits in enhancing immunity, such as micronutrients is in exhibiting pleiotropic roles in supporting immune function. the vitamins and minerals support to develop and maintain the physical barriers, produce and activate antimicrobial proteins ( ) . some other mechanisms of micronutrients are supporting the growth, differentiation, and motility/chemotaxis of innate cells; phagocytic and killing activities of neutrophils and macrophages, and promotion of and recovery from inflammation (e.g. cytokine production and antioxidant activity ( ) . the potential mechanisms of the fruits may back to the antiviral immune induction, the modulation of immunoregulatory defense, induction of autophagy and apoptosis, genetic or epigenetic regulation ( ) . stimulation of defensins and cathelicidins may reduce the replication of the virus and raise the levels of anti-inflammatory cytokines, and reducing levels of pro-inflammatory cytokines ( ) . here our hypothesis is that a higher intake of fruits suppresses the role of stimulation of defensins and cathelicidins. the common denominator that reflects the role of nutrition and dietary recommendations against viral infections; including covid- is the relation between diet and immunity ( ) . this is why we made our hypothesis based on the immunological effects of a higher intake of fruits in patients with covid- by taking into account the patients' ages. the evidence highlights that diet has an important effect on the immune system and disease vulnerability of peoples. the role of nutrients or nutrient combinations back to their effects on the immune system through the cell activation, modification in the production of signaling molecules, and gene expression ( ) . the relation of fruits and beans and legumes on crude mortality rate is weak (p= . and p= . , respectively) in contrast with the strong relation of sugar-sweetened beverages (ssbs) (p< . ). the possible role of sugar-sweetened beverages on infection rate may back to its role in weight gain and the risk of obesity. a review study of observational and clinical trials showed that a higher intake of ssbs raised the risk of weight gain and obesity ( ) . the evidence has been confirmed elsewhere ( , ) . accordingly, maccioni et al. ( ) recruited individuals aged - in a cross-sectional study on airway infection in germany. the study reported that obese persons have a consistently higher frequency of upper and lower respiratory tract infections (rtis). the evidence has been reported elsewhere ( , ) . obesity is responsible for the dysregulation of the immune system through mediation in different immune, metabolic, and thrombogenic responses ( ) . the higher intake of ssbs has been reported in high-income countries ( ) . the effect of higher calcium intake on raising infection rates could be due to the effect of calcium on the risk of some other chronic diseases rather than its direct effect. a meta-analysis showed the increased incidence of myocardial infarction in persons who consume higher levels of calcium with a pooled relative risk of . , % confidence interval . to . , p= . ( ) . in addition, calcium has been reported as a trigger for ischemic cell death ( ) . the daily recommended allowance/intake of the dietary factors are different across the countries. it is required to mention that food intake varies markedly based on the sociodemographic factors; like age gender, and educational level. we did not make stratification the results of the study based on the socio-demographic aspects since the who has not published the covid- confirmed cases according to age, gender, and educational level. besides, the cross-country caparison of individual-level dietary data is challenged by the dietary surveys performed with various survey characteristics and data collection methods with a possible influence in the comparison of the results. however, we used the fao dietary data that represent the nationally representative sample of all age-sex, and educational level categories. the present study showed the higher intake of fruits and sugar-sweetened beverages had a positive effect on infection and mortally rates by covid- , respectively. in contrast, the higher intake of beans and legumes had a negative effect on both increasing infection and mortality rates. the possible reason for the role of fruits and sugar-sweetened beverages on infection and mortally rates back to the indirect effect of weight gain and obesity and the role of age. the authors do not declare any conflicts of ineptest. global, regional, and national comparative risk assessment of behavioural, environmental and occupational, and metabolic risks or clusters of risks, - : a systematic analysis for the global burden of disease study importance of government policies and other influences in transforming global diets global panel on agriculture and food systems for nutrition: food systems and diets: facing the challenges of the st century geographic and socioeconomic diversity of food and nutrient intakes: a comparison of four european countries meatless days" or "less but better"? 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on risk of myocardial infarction and cardiovascular events: meta-analysis calcium in ischemic cell death key: cord- -fkwtgq authors: hariharan, ramya title: when to relax social distancing measures? an arima based forecasting study date: - - journal: nan doi: nan sha: doc_id: cord_uid: fkwtgq the spread of the novel coronavirus across various countries is wide and rapid. the number of confirmed cases and the reproduction number are some of the epidemiological parameters utilized in scientific studies for the analysis and prediction of the viral transmission. the positive rate, an indicator on the extent of testing the population, aids in understanding the severity of the infection in a given geographic location. the positive rate for selected countries has been considered in this study to construct arima based statistical models. the goodness of fit of the models are verified by the investigation of residuals, box-luang test and the forecast error values. the positive rates forecasted by the arima models are utilized to investigate the scope for implementation of relaxations in social distancing measures in some countries and the necessity to tighten the rules further in some other countries. in the first two decades of the st century, the re-emergence of infectious disease is on the rise. predominantly originating from zoonotic viruses, the outbreak of viruses such as ebola, zika, h n etc., have resurfaced frequently in the past few years [ , ] . recently, severe acute respiratory syndrome coronavirus (sars-cov- ), a novel virus which belongs to the family of human coronavirus has originated in the wuhan province of china in december [ , ] . through an intermediate host, the transmission of the virus from bat to humans has occurred. the virus has a higher infectivity rate as compared to the influenza viruses which is manifested by its high reproduction number. owing to the severity of the respiratory illness world health organization (who) had declared sars-cov- as a pandemic in march . the virus has rapidly spread across the globe and almost all the countries are engulfed under its net. as on september , as high as countries around the world have reported a total of , , confirmed cases of sars-cov- . the global death toll has also reached about , deaths. all the affected countries are battling to reduce the transmission by proclaiming stringent guidelines on safety precautions, social distancing, lockdown, home/institutional quarantine and travel restrictions [ ] . in spite of these measures, the number of confirmed cases in most of the countries is on the rise. in particular, highly populated countries such as brazil, usa, india etc., have emerged as epicenters for the infectious disease [ , ] . numerous research groups have utilized the epidemic data to understand and the trend and trajectory of the disease. most of the studies have been conducted by analyzing the countrywise or city-wise data on the number of confirmed cases, recovery rates and mortality rates [ , ] . machine learning, deep learning, artificial neural networks based algorithms have been utilized to forecast the transmission of the disease [ ] [ ] [ ] . however, the re-emergence of sars-cov- cases in countries such as new zealand, spain, germany, iran etc., has raised speculation on the possibility of a second epidemic wave. the testing for infection which aids in the effective isolation of infected persons and also tracing their contacts is very important to overcome the viral dissemination [ ] . testing the population also helps in efficiently utilize the medical resources, which is being exploited in the pandemic situation. in this study, an interesting epidemiological parameter, namely, the positive rate has been utilized to frame guidelines pertaining to social distancing measures. positive rate is an indicator on the level of testing with respect to the extent of outbreak. the time series data collected from some of the worst affected countries of the world has been used to build the auto-regressive integrated moving average (arima) models. the countries are chosen so as to assess concerns such as increase in sars-cov- cases as a function of population, economy, testing rate and travel regulations. the study provides a new perspective to understand the current pandemic situation and also provides insight on efficiently using the available resources. the data on positive rate has been collected from open source database of our world in data [ ] . as on the first week of september , usa, russia, south africa, india, mexico and spain are some of the countries badly affected by the deadly virus. therefore, the master dataset has been filtered to obtain the positive rates for the chosen countries. the data was collected from april to september . the country-based positive rates are shown in figure which also highlights the countries selected in this study. the data was checked for missing values which was approximated by the corresponding monthly average. the as collected data showed a time series behavior. in order to build a suitable model to forecast the trend in variation of positive rate, the steps such as test for stationarity, identification of parameters, estimation, evaluation of model performance and forecasting are performed on the collected data. among the statistical models, the most powerful and robust procedure is the method established by box and jenkins [ ] . the arima model which is a combination of the autoregressive (ar) and moving average (ma) models has been used in this study to analyze and forecast the time series data [ ] . the "arima" function in the "forecast" package of r programming (version . . ) was used to build the model. in addition, packages such as "timeseries", "metrics" and "ggplot " were used for forecasting, statistical analysis and visualization respectively. the positive rate values for the chosen countries such as usa, russia, south africa, india, mexico and spain are converted into their corresponding time-series plots. depending on the nature of the time-series data, suitable arima models are built for each of the countries. initially, the unit root test is conducted to ascertain the non-stationarity of the time series. in order to apply the statistical theories, it is mandatory for the time series to be stationary. one of the popular tests to estimate the stationarity of data is the augmented dickey-fuller (adf) test [ ] . it is observed from table that the data from all the chosen countries lacked stationarity as manifested by their p values > . . the probability of significance, p-value, should be < . to confirm that the time series is stationary. a non-seasonal arima model is generally represented by the parameters (p,d,q). the primary step in fitting an arima model is the determination of the order of differencing, 'd' necessary to stationarize the series [ ] . the country-wise estimated order of difference required to yield the positivity data series stationary are shown in table . the adf test has been repeated on the differenced data series which showed p-values < . thereby confirming its stationarity. table . subsequently, the arima models are built using the least-squares estimation process. the accuracy of the arima models is diagnozed using akaike's information criterion (aic) and the schwartz bayesian information criterion (bic). aic, shown in equation , is a widely used measure of a statistical model to quantify its goodness of fit and parsimony. a good model is identified as the one which has minimum aic among all the other models [ ] . the models are selected based on this criterion and the corresponding aic values are listed in table . where l is the likelihood value, n is the number of measurements recorded and k is the number of estimated parameters. the however, the outliers are also retained in this study to build a realistic model. similarly, the estimated autocorrelation coefficients (acf) of the residuals pertaining to the various models are shown in figure . it is evident that for all the models, the lags shown in figure occur well within the confidence interval. it is also noticed from table that the acf are statistically insignificant which implies that the residuals have random values and confirm the lack of noticeable correlation in the residuals series [ ] . the histogram of residuals are shown in figure corresponding to the chosen countries. the histograms of all the arima models show a predominant normal distribution trend of the residuals. they also confirms the lack of significant variance. the mean values are also noted to be near-zero. the observation is also confirmed from the low mean error (me) values compiled in table . the investigation on the residuals confirm that the built arima models have a good fit with the actual values. the arima models are also verified by the box-ljung test which provides a statistical evidence of a good fit [ ] . the recorded p values for all the arima models are tabulated in table . figure shows a country-wise -day forecasted values of positive rate with a confidence interval of %. figure a shows a steady reduction in the positive rate for usa from % to . % in the forthcoming month. the forecast confirms that the current testing rate in usa is adequate to isolate the infected population. who has provided guidelines to observe the positive rate for days before taking decision on relaxing social distancing measures. it has also recommended a positive rate of % or lesser as a metric to evaluate the viral spread and to frame government policies [ ] . based on the forecasted positive rate, in the forthcoming months usa would comfortably meet the criterion and policies for social distancing shall be taken favorable to allow people interaction and movement. figure f shows the forecasted positive rates for spain. the values show a moderate increment from . % to . %. the positive rate is higher than the who prescribed limits and the country should increase the testing rate by at least - % to reduce the positive rate to below %. in the case of spain this measure is very critical because it is a european union country which is well-connected by land and other means of transport with most of the european countries. hence the government should not only increase the testing rate, but also implement stringent rules until the positive rate falls below %. this study provides an insight on the current and forecasted trend in the positive rate in the selected countries. the countries such as usa and south africa, similar to australia and south korea, are on the path of attaining low positive rates [ ] . hence, the guidelines introduced to mitigate the transmission of sars-cov- such as restriction on people movement and social distancing could be relaxed in a month in these countries. however, countries such as india, mexico and spain should adopt more precautions to protect their population by increasing the testing rates. the social distancing rules should also be strictly enforced in these countries for at least a few more months until the positive rate is < %. countries such as russia should be more proactive in maintaining the low positive rates in order to avoid the outbreak of a second wave of the pandemic. this knowledge is important to properly assess the key decision to be implemented on social distancing and lockdown policies. these measures are essential because the sars-cov- pandemic holds the potential to spread more widely and quickly which can have a devastating impact on not only the economy of the affected country but also the global economy. in this study, the positive rate for different countries is utilized to build arima based forecasting models. the model has been carefully built by testing for stationarity, appropriately choosing the key parameters and validating its accuracy. the verification of the models is conducted by observing the residuals and from the results of the box-ljung test. the forecasted values for usa and south africa showed than in days, the positive rate shall be consistently below %. this would pave way to relax the existing stringent measures adopted by the government to reduce the viral transmission. however, in countries such as india, mexico and spain, the positive rate is beyond the safe limit of about %. in india, even though the positive rate is not inherently high, precarious measures such as active testing would prevent a steep increase in the positive rate. in mexico, the current testing rates are highly insufficient which need to be increased by at least - %. in spain, the testing rate should be consciously increased by - % in order to prevent the cross-country spread of the pathogen. this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. the author declares that they have no conflict of interest. estimation of the reproductive 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of cases and contacts our world in data, coronavirus (covid- ) testing -statistics and research -our world in data time series analysis of aerosol optical depth over new delhi using box-jenkins arima modeling approach chapter -time series: understanding changes over time distribution of the estimators for autoregressive time series with a unit root study of arima and least square support vector machine (ls-svm) models for the prediction of sars-cov- confirmed cases in the most affected countries trend analysis and arima modelling of pre-monsoon rainfall data for western india research on covid- based on arima modelΔ-taking hubei, china as an example to see the epidemic in italy public health criteria to adjust public health and social measures in the context of covid- , who pathological findings of covid- associated with acute respiratory distress syndrome the author is thankful to our world in data organization for the valuable data. the author profoundly thanks the management and the principal of b.m.s. college of engineering, bangalore for their support. key: cord- - xgjdhkx authors: faria, nuno r; de vries, michel; van hemert, formijn j; benschop, kimberley; van der hoek, lia title: rooting human parechovirus evolution in time date: - - journal: bmc evol biol doi: . / - - - sha: doc_id: cord_uid: xgjdhkx background: the picornaviridae family contains a number of important pathogenic viruses, among which the recently reclassified human parechoviruses (hpevs). these viruses are widespread and can be grouped in several types. understanding the evolutionary history of hpev could answer questions such as how long the circulating lineages last shared a common ancestor and how the evolution of this viral species is shaped by its population dynamics. using both strict and relaxed clock bayesian phylogenetics we investigated ) the substitutions rates of the structural p and capsid vp regions and ) evolutionary timescale of currently circulating hpev lineages. results: our estimates reveal that human parechoviruses exhibit high substitution rates for both structural p and capsid vp regions, respectively . × (- )( . – . × (- )) and . × (- )( . – . × (- )) substitutions per site per year. these are within the range estimated for other picornaviruses. by employing a constant population size coalescent prior, the date of the most recent common ancestor was estimated to be at around ( – ). in addition, by looking at the frequency of synonymous and non-synonymous substitutions within the vp gene we show that purifying selection constitutes the dominating evolutionary force leading to strong amino acid conservation. conclusion: in conclusion, our estimates provide a timescale for the evolution of hpevs and suggest that genetic diversity of current circulating hpev types has arisen about years ago. parechoviruses belong to the picornaviridae family which includes other pathogenic viruses such as foot-and-mouth disease virus (fmdv), hepatitis a virus, enteroviruses and rhinoviruses [ , ] . the parechovirus genus includes two species: human parechoviruses (hpev) and the zoonotic ljungan virus. hpev are non-enveloped pathogens with a single-stranded genomic rna of positive polarity with around . nucleotides organized into a single long open reading frame in between a 'utr and 'utr. the open reading frame can be divided into three main regions: p (encoding capsid proteins vp , vp , vp ), p (nonstructural proteins) and p (nonstructural proteins, including the viral rna polymerase) [ ] [ ] [ ] . in hpev, out of the three capsid proteins that constitute the monomeric units of the viral icosahedric-shaped capsid [ ] , vp protein plays a crucial role in cell entry via interaction of an arg-gly-asp (rgd) triplet with integrins on the cell surface [ ] . however, some hpevs (among which the type strains) lack the rgd motif in vp , and their mode of cell recognition and entry is less clear [ ] . typing of hpev is based on the vp sequence providing a reliable locus to type all the identified hpev strains as described for enteroviruses by oberste et al [ ] . as a result, the majority of hpev available nucleotide data concerns the vp gene. in general, hpev is transmitted by the oral-fecal route causing in most cases relatively mild respiratory and gastrointestinal symptoms [ , ] , though conditions such as bronchiolitis [ ] and severe neonatal infections [ , ] have also been reported. hpev and hpev were first isolated in and classified by serotyping as enteroviruses, respectively echovirus types and [ , ] . hpev was first described in [ ] and is associated with more severe conditions related to cns symptoms [ , , ] . subsequently, improvements in hpev-specific screening tools allowed a successful identification of hpev and hpev throughout north america, japan and europe [ ] [ ] [ ] [ ] [ ] . moreover, an hpev variant originally classified as hpev -connecticut was reclassified as hpev [ ] . currently, sequences have become available for two novel types that were recently isolated in pakistan and brazil [ , ] and in the netherlands one more novel type was identified (hpev , [ ] ). unfortunately sequences of the hpev types to are not available for analysis yet. of all types, hpev and hpev are the most prevalent strains [ , ] . understanding the mechanisms underlining pathogenicity and persistence of pathogens in human populations is an important aspect of disease epidemiology and control. fixation of mutations into nucleotide substitutions, a key principle behind phylogenetic signatures, is shaped by major evolutionary forces such as selection (molecular adaptation deriving from an increasing fitness of a corresponding phenotypic trait) and genetic drift (stochastic gene sampling process at reproduction) [ , ] . a useful tool to detect and measure selection in viral gene sequences is the ratio between synonymous (ds) and nonsynonymous (dn) substitutions. whereas a ratio above . is an indicator of positive selection operating at the amino acid sequence level [ ] , significantly lower values are generally referred to as purifying selection and refer to preservation of the phenotypic trait. rna viruses yield the highest mutation rates of all groups of pathogens which is approximately six orders of magnitude higher than in most dna organisms [ , ] . in the context of viral population genetics, substitution or evolutionary rates can be defined as the number of fixed mutational changes that accumulate in the population per nucleotide site per unit of time [ ] . this rate is driven by the short-generation times of viruses and their error-prone rna polymerase proteins lacking proofreading activity. combined with their small genomes, these characteristics make rna virus ideal models for evolutionary research [ , , ] . in addition, recombination events may also play a role in rna virus evolution [ ] . while lacking a fossil record, evolutionary histories of rna viruses can be calibrated because they represent 'measurably evolving populations', in which genetic diversity accumulates over a timescale of human observation [ ] . their evolutionary history and population dynamics can be reconstructed by means of genealogy-based coalescent approaches using nucleotide sequences sampled over an epidemiological time frame in order to estimate timed viral ancestry as well as the rates of genetic change [ , ] . the most advanced methods operating on time-stamped sequence data use bayesian metropolis-hastings markov chain monte-carlo (mcmc) algorithms that accommodate for the uncertainty of phylogenies rooted in time. here, we estimated the substitution rates for the p and vp regions of hpev with such a bayesian approach, which provides a statistical framework for evolutionary analysis [ ] . the identification of several novel types within the last few years may be conceived as a relatively recent introduction of hpev into the human population, but this is not necessarily the case. by reconstructing the evolutionary history of hpev we shed light on this issue. we investigated when current hpev diversity emerged by determining the time of divergence from the most recent common ancestor (tmrca). dataset comprised nucleotide sequences from the p structural region ( nt) from different hpev isolates ( sequences of hpev , sequence of hpev , sequences of hpev , sequences of hpev , sequences of hpev , sequences of hpev , sequence for hpev and sequence for hpev ). dataset comprised nucleotide sequences of the vp capsid region ( nt) ( sequences of hpev , sequences of hpev , sequences of hpev , sequence of hpev , sequence of hpev , sequences of hpev , sequence of hpev , sequence of hpev and sequence of hpev ). to date, sequences of hpev - have not been made available [ ] . the accession numbers of the sequences from both data sets are available in additional file . sampling date (year) for dataset ( - ) and for dataset ( - ) was either collected directly from genbank record or following direct contact with the relevant authors. multiple alignments of the p and vp regions of hpev were conducted in clustalw [ ] and sequences were edited manually with se-al v . [ ] . overall evolutionary rates for p and vp regions were measured as the number of nucleotide substitution per site per year (s/s/y). relevant parameters were summarized as the median of posterior distributions by bayesian coalescent markov chain monte carlo algorithm implement in the bayesian evolutionary sampling trees (beast) software package version . . [ ] . to identify the optimal substitution model we performed a maximum likelihood analysis using the modelgenerator package [ ] . the model that best fit both sequence datasets was general time reversible (gtr) model with a discretised γ-distribution (gtr+Γ), allowing for nucleotide rates to vary among sites within the protein coding sequence alignments. codon partitions ( + )+ were applied to both alignments, keeping first and second positions (mostly to non-synonymous changes) in one partition and the third position (related to increase redundancy and prone to synonymous changes) in a separate partition [ ] . relative rate parameters were estimated in separate for each partition, in order to accommodate rate variation at the third codon position. we employed both strict and relaxed lognormal molecular clocks, the latter allowing rate variation among branches [ ] . the coefficient of variation (σ r ) was used as a quantification of the rate variation among branches (σ r > . was considered as significant rate variation among branches) ( table ) . a constant size demographic model was used as coalescent prior. each alignment of both data sets was analyzed using markov chain monte-carlo (mcmc) computations run over a sufficient time to achieve convergence of the chains, which was analyzed by inspection of the mcmc samples using tracer . [ ] . the % highest posterior density (hpd) interval is the shortest credible interval that contains % of the samples values. statistical uncertainties of the substitution rates and the tmrca were summarized as the lower %, median, and upper % values of the hpd. out of the tested models (gtr + Γ, both with strict and relaxed lognormal molecular clocks), the clock model that performed better was the lognormal molecular clock, which yielded the highest marginal likelihood. clock models were also compared in terms of bayes factors (bf, table ). the relaxed model clock following a lognormal distribution was also supported by the highest log bf as suggested [ ] . the fact that a relaxed lognormal molecular clock fits best to our data was consistent with an estimated coefficient of variation of . and . (respectively, for dataset comprising p and vp regions) that reflected significant rate heterogeneity, thus rejecting a strict molecular clock. the resulting trees for each run were summarized using tree-annotator and the maximum clade credibility tree was visualized with figtree v . . [ ] . beast xml files are available as additional files , , and . overall selective pressures acting on vp antigenic region were estimated by using the codeml program in the paml package [ ] . we used site models m (with a discrete distribution of categories and accounting for sites not allowed to be positively selected) and m (estimates dn/ds for an extra class (p ) of sites, accounting for positively selected sites with dn/ds> ). models were compared by means of likelihood ratio test and statistical support was taken from the bayes-empirical-bayes output (beb, see additional file : log-likelihood and parameter estimates for paml analysis) [ ] . to detect adaptative molecular evolution, we used the complete dataset . we first identified the best-fitting substitution model for the hpev sequences using the modelgenerator package (gtr + Γ) [ ] , and tested whether the evolution of the p and vp genetic regions was better described by a strict or relaxed lognormal molecular clock. a relaxed lognormal molecular clock provided a better fit to both datasets according to bayes factor (bf) analyses (p : log bf = . and vp : log bf = . , table ). this is in accordance with significant rate variation among the branches of the inferred phylogeny as measured by a non-zero coefficient of variation (σ r ) obtained with the relaxed molecular clock analysis (p : σ r = . ; vp : σ r = . ) (see methods for details). using the available p and vp dated sequences of hpev, our analysis inferred a similar rate of nucleotide substitution for both regions (p median: . × - s/s/y, % hpd [ . × - , . × - ]; vp table ). the higher rate indicated for the vp region is possibly related to its antigenic properties, perhaps reflecting a difference in the level of gene expression or mirroring the involvement of the vp capsid protein in the viral entry mediated by cellular integrins. despite our study focused on the available sequences of hpev, more accurate estimates could probably be obtained with broader and more homogenous sampling timescale, preferably for all types. yet, this may be a daunting task because it is difficult to obtain older samples and some of the hpev types e.g. hpev , hpev , hpev and hpev appear to be relatively rare (see e.g [ , ] ). moreover, a common pitfall on estimating evolutionary rates is its underestimation due to mutational saturation of synonymous sites [ ] [ ] [ ] [ ] . by using a gamma distributed substitution model, we assured that rate variation among sites was allowed. therefore, the effect of possible saturation of synonymous sites was alleviated by permitting a proportion of these sites to change at a higher rate [ ] . in addition, we used partitioning in codon positions that allows different codon positions to have different substitution rates (and different amount of rate heterogeneity) (see methods for details) [ , ] thus further accommodating rate variation among synonymous and non-synonymous positions. the high rates of evolutionary change obtained in this study are in accordance with the evolutionary rates of other rna viruses [ , ] . consistently, hpev replication mechanism relies on an rna-dependent rna polymerase that lacks proofreading capacity. this increases the number of mutations incorporated in viral genomes over time and settles the ground for a relatively rapid genetic diversification [ ] . the evolutionary rates of a few members of the picornaviridae family have been studied. despite the fact that most of the studies used different evolutionary frameworks, the rate of evolutionary change estimated in this study for the capsid region of hpev vp is ) faster than the rate of hepatitis a virus [ ] , ) resem-bles the rate estimated for the antigenic region of echovirus [ , , ] and finally ) it is nearly one order of magnitude lower than the rates of poliovirus ( . × - s/s/y) [ ] or fmdv ( . × - s/s/y) [ ] . rna viruses are the most suitable object of study for rates of change and divergence times. this is due in large part to the rapid rate at which they evolve allowing genetic diversity to accumulate within a timescale approximately the same as mutations are fixed in viral populations [ ] . yet, a deeper understanding of the replication machinery of hpev (e.g. generation times, fidelity of rna polymerase) may deliver insights on the molecular basis of these high rates of evolutionary change [ ] . according to our analysis based on hpev vp available sequences, these viral species diverged from their most recent common ancestor (mrca) at the year ( % hpd [ - ]) ( figure , table ). moreover, and focusing on the two most recently isolated types (hpev [ ] , hpev [ ] . taken together, we suggest that the genetic diversity of the currently circulating hpev types has arisen around years ago (figure ). the wider % bayesian credible intervals obtained for the estimates using dataset composed by the total of available p sequences to date (table ) probably reflect a less heterochronous sequence data. yet, an identical timescale was obtained when performing the mcmc approach with the dataset comprising the p region ( , % hpd [ - ]) ( table ). despite holding new pieces to solve the puzzle of hpev origins, the evolutionary rates and the timescales for the most recent common ancestor and type lineage-splitting events, may be better framed once a larger number of sequences are available [ ] . however, the overlapping of the % bayesian credible intervals obtained in our analysis for both genomic regions indicates that our estimates on the tmcra of the hpev lineages are robust ( table ) . one facet of fast evolving rna viruses that induce acute infections (as the case of hpev) is that they are likely candidates for jumps between species boundaries [ ] . while the latter appears to be clearly established for e.g. sars-cov or influenza h n , a zoonotic link remains to be elucidated for hpev. because ljungan virus shares a close phylogenetic proximity with hpev virus, it is likely that both species have had a common ancestor [ ] . moreover, the reservoir host for ljungan virus is myodes glareolus, a widely distributed rodent commonly named as bank vole [ ] . despite the connection of ljungan virus infection and human disease still remains to be clarified, bank voles are recognized as the reservoirs of other infectious agents, e.g. puumala hantavirus [ ] and have been linked to a significant number of outbreaks over europe [ ] [ ] [ ] . bayesian time-scaled phylogeny of hpev based on vp sequence analysis figure bayesian time-scaled phylogeny of hpev based on vp sequence analysis. maximum clade credibility tree obtained with beast with a constant size coalescent prior showing lineage splitting events (nodes a-f) since the most recent common ancestor to the presently circulating hpev types. the divergence times correspond to the mean posterior estimate of their ages (in years). for the tmrca, the correspondent % bayesian credible intervals are shown (median ). time axis is shown in years and ranges from the tmrca to the present year. deeper and some subtype nodes with posterior probability of higher than . are pointed out. each colour corresponds to a specific hpev, as indicated in the box on the right. the dashed grey circle depicts the extent of genetic diversity of the sampled hpev strains. hpev- -"harris-like" strains (*) clustered separately from the contemporary hpev- . in search for the driving force that shapes the evolution of the hpevs, we looked at the ratio of non-synonymous-tosynonymous substitutions (the dn/ds ratio) [ ] . for most codons in the vp region the ratio is < . (figure ). we noticed a few sites that tend to escape from purifying selection displaying dn/ds values > . (position q , a , g ), or even > . (position n of our alignment, see additional file ), however with statistically poor support (see additional file , log-likelihood and parameter estimates for paml analysis). also other studies have found an overall low dn/ds ratio for the hpevs [ , ] . our analysis confirms on a codon level that throughout the structural region strong purifying selection is dominant, leading to the conservation at the level of the amino acid sequence. future analysis may shed lights not only in a unified framework of evolution for this viral species but also help preventing major burdens associated with hpev pathogenicity. the hpev are highly prevalent human rna viruses and thus far no studies have addressed the evolutionary history of these pathogens. the bayesian analysis presented here first indicates that the structural p and the capsid vp region of this viral species evolve at a high rate of evolutionary change (~ - substitutions per site per year). additional genomic and epidemiological data will help to reveal the relation between such rates and the widespread of this viral species. we also show that the currently circu-lating hpev types have shared a common ancestor around four centuries ago. since then, hpev evolved into different lineages that have spread widely. overall, a strong tendency for phenotypic conservation could be observed, suggesting that genetic drift plays an important role in the generation of the diversity within the regions under investigation. in summary, by delivering insights into the evolutionary mechanisms of hpev, this study provides the foundations for a unified understanding of hpev evolution. recombination and selection in the evolution of picornaviruses and other mammalian positive-stranded rna viruses human parechovirusesbiology and clinical significance a new picornavirus isolated from bank voles (clethrionomys glareolus). virol entry of human parechovirus isolation and identification of a novel human parechovirus pallansch ma: comparison of classic and molecular approaches for the identification of untypeable enteroviruses enteroviruses in human disease human parechovirus types , and infections in canada human parechovirus and neonatal infections human parechovirus infections in dutch children and the association between serotype and disease severity properties of echo types , and viruses human parechoviruses as an important viral cause of sepsislike illness and meningitis in young children analysis of a new human parechovirus allows the definition of parechovirus types and the identification of rna structural domains fourth human parechovirus serotype isolation and characterization of novel human parechovirus from clinical samples human parechovirus type , , , , and detection in picornavirus cultures prevalence, types, and rna concentrations of human parechoviruses, including a sixth parechovirus type, in stool samples from patients with acute enteritis genomic characterization of novel human parechovirus type novel human parechovirus from brazil high prevalence of human parechovirus (hpev) genotypes in the amsterdam region and identification of specific hpev variants by direct genotyping of stool samples longitudinal observation of parechovirus in stool samples from norwegian infants the population genetics and evolutionary epidemiology of rna viruses unifying the epidemiological and evolutionary dynamics of pathogens a method for detecting positive selection at single amino acid sites mutation rates among rna viruses rates of evolutionary change in viruses: patterns and determinants the phylogeography of human viruses evolutionary history and phylogeography of human viruses inference of viral evolutionary rates from molecular sequences beast: bayesian evolutionary analysis by sampling trees clustal w: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice molecular evolution assessment of methods for amino acid matrix selection and their use on empirical data shows that ad hoc assumptions for choice of matrix are not justified graphical exploratory data analysis of rna secondary structure dynamics predicted by the massively parallel genetic algorithm relaxed phylogenetics and dating with confidence bayesian selection of continuous-time markov chain evolutionary models bayes empirical bayes inference of amino acid sites under positive selection calibration of multiple poliovirus molecular clocks covering an extended evolutionary range codon substitution in evolution and the "saturation" of synonymous changes time dependency of molecular rate estimates and systematic overestimation of recent divergence times molecular clocks and the puzzle of rna virus origins a phylogenetic method for detecting positive epistasis in gene sequences and its application to rna virus evolution basic concepts in rna virus evolution bayesian coalescent inference of hepatitis a virus populations: evolutionary rates and patterns evolution of circulating wild poliovirus and of vaccine-derived poliovirus in an immunodeficient patient: a unifying model molecular epidemiology and evolution of enterovirus strains isolated from to genetic diversity in the vp gene of foot-andmouth disease virus serotype asia sensitivity of the relative-rate test to taxonomic sampling molecular analysis of three ljungan virus isolates reveals a new, close-to-root lineage of the picornaviridae with a cluster of two unrelated a proteins molecular evolution of puumala hantavirus outbreak of puumala virus infection puumala hantavirus infection in humans and in the reservoir host, ardennes region hantavirus outbreak widespread recombination within human parechoviruses: analysis of temporal dynamics and constraints we are grateful to philippe lemey for helpful comments on the paper and for computational assistance. also, we thank dr. richard hoffmann, dr. vladimir lukashov and to three anonymous reviewers for their valuable comments on the paper. we thank wilma vermeulen-oost and ron berkhout for culturing the harris-like type virus, filipa campos for graphical design assistance on figure and katja wolthers for critical reading of the manuscript. lia van der hoek is supported by vidi grant . . from the netherlands organization for scientific research (nwo). nrf and lvdh designed and conceived the study. mv, nrf and kb collected and aligned the sequences. nrf and fjh carried out the analysis and analyzed the data. nrf and lvdh wrote the paper. all authors read and approved the final manuscript. the dn/ds ratios per site in vp region of hpev key: cord- -z lvcb z authors: wang, xiubin bruce; ma, chaolun title: controlling the hidden growth of covid- date: - - journal: nan doi: nan sha: doc_id: cord_uid: z lvcb z the covid- pandemic has plagued the world for months. the u.s. has taken measures to counter it. on a daily basis, newly confirmed cases have been reported. in the early days, these numbers showed an increasing trend. recently, the numbers have been generally flattened out. this report tries to estimate the hidden number of currently alive infections in the population by using the confirmed cases. a major result indicates an existing infections estimate at about - times the daily confirmed new cases, with the stringent social distancing policy tipping to the upper end of this range. it clarifies the relationship between the infection rate and the test rate to put the epidemic under control, which says that the test rate shall keep up at the same pace as infection rate to prevent an outbreak. this relationship is meaningful in the wake of business re-opening in the u.s. and the world. the report also reveals the connections of all the measures taken to the epidemic spread. a stratified sampling method is proposed to add to the current tool kits of epidemic control. again, this report is a summary of some straight observations and thoughts, not through a thorough study backed with field data. the results appear obvious and suitable for general education to interested policymakers and the public. the outbreak of the cornonavirus covid- is an unfortunate incident in the st century that suddenly plagued numerous countries. it has brought much of the world economy to a halt. countries quickly motioned to put it under control. it is an anxious, agonizing process checking the newly confirmed cases of infection and death each day for such an extended, long time. people have observed italy, spain, and other countries after china that have been inflicted by this pandemic. now the u.s. became the seemingly world epicenter with a total confirmed infections exceeding one and half million [ ] . as people watch on the daily spread of this pandemic, few know when this pandemic will be put to an end or whether it will spiral out of control again, although pundits worldwide have publicized many findings and predicts. what the general public observe each day are newly confirmed cases from day to day as well as the cumulative totals. the trend of the newly confirmed cases each day was increasing in the early days and is now pretty flattened out overall under the prevalent shelter-in-place policy [ ] . what does this trend mean ? we try to answer the question and also examine a condition under which a stable, flat trend is sustainable. such an examination appears especially meaningful as the u.s. and the world approach to massive business reopening. additionally, in a later summary of all measures taken as of now, this report tries to clarify how they each take effect in the control of this pandemic in connection to the condition we identify here. this report proposes a sampling method for testing the communities. it does not discuss the feasibility of the proposed measures in terms of its technical and fiscal constraints. this report did not result from an intensive study. it does not contain field data but only reveals some inherent structural relationships. in an attempt to understand the driving factors of the epidemic spread, our perspective is different from most mainstream literature of epidemiology. the literature in epidemiology such as [ , , ] generally simulate the interactive process of epidemic transmissive behaviors in a closed region by also considering population migration in and out in order to duplicate the transmissive process. the simulation realizes the mechanism expressed in an array of partial differential equations [ , ] , in which the transmission rate is affected by the percentage of the infected in a nonlinear manner. similar to the literature in epidemiology such as [ , ] , we try to understand and gauge the hidden world of the infected population, including the latent and active ones that are not detected yet. however, our method to estimate the undetected number of currently latent and active infections is based on the publicized numbers of the daily confirmed cases without having to resort to the epidemic process simulation. our result is simpler and easier to understand and use. note that this note treats the latent and active as in one undetected group with a comprehensive infection rate. we allow a different aggregate infection rate for each day. our weakness is that this report takes infection rate and detection rate as given parameters. this report does not study their specific values. current literature report that the total infected population could be six to ten times the cumulative total confirmed [ ] . our finding shows that the total currently latent and active cases can be six to sixty times the incremental daily confirmed total in today's situation that the daily confirmations seem on a flat trend. this findings implies the total infections from to about times the total confirmed infections. one may also gauge the growth or declination of the infections in light of a necessary and sufficient condition for epidemic control that we have found in this report. in the remainder of this report, we will detail our discussion and derivation of the result. first, we describe the problem in a technical term that we believe characterizes the epidemic process well. table tabulates the notation in the report. we first introduce the epidemic problem. problem statement there is a group of infected people on day one. out of them, n is confirmed and quarantined. on day i, each infected case that is not confirmed and quarantined, referred to as hidden cases, grows at a daily rate of r i into more cases. at the end of each day i, hidden cases each have a probability p i being detected and put into quarantine while the undetected cases continue the infection the next day. the growth rate of r i is the net growth rate, which is the difference between the new infections deducted by the recovered and dead. day by day over a period of time, newly confirmed cases are reported by the number n , n , ..., and n n .the study is to use the daily confirmed numbers of infections to estimate the hidden infections and their trend of growth or declination. the goal is to propose measures for the epidemic control. clearly, there are a number of infections hidden out in the communities undetected. note that the hidden cases here are referred to as undocumented in [ ] . the number of hidden cases is the primary interest here. be aware that the growth rate r i here is different from the transmission rate in the conventional epidemiology literature [ ] , where the transmission rate is the number of infections that a currently active one may incur per day during the short span of active period. we assume that the confirmed cases have been perfectly quarantined and have lost their ability of further infection. one may consider their remnant infectious ability, even if under quarantine, is implicitly incorporated into the infectious capability of the hidden cases by allowing for a slightly higher rate r i . we simplify the process from the perspective of someone outside epidemiology by assuming each infected case has an equal average growth rate, which may not be accurate. one may take this growth rate as an aggregate measure of all the hidden cases as a whole. note we include the latent also in the hidden cases. for covid- , some reports declare that the latent cases may also be infectious. the net infection (or net growth) rate is random. it is reasonable to assume a constant average rate with fluctuations (e.g., random outcomes) between days for a period over which the test means, ability, and policy do not change significantly. we assume a detection rate p i on day i to represent a percentage of the infections that are confirmed and quarantined on the day. the detection rate has to do with many measures, such as contact tracing of newly confirmed cases. the detected cases are the confirmed cases that the public observes in the daily report. each day, the reported cases are the tip of an iceberg, which public opinions and public policies are generally based upon. let's show the growth process of the infected population in the hindsight. assume the epidemic moves forward according to the numbered days, day , , ..., n, n+ ,.... again, there are n new cases confirmed on day . clearly, there holds p n = n where n ≥ as on table . on table , infected population is the number of infected people including those detected and quarantined on the day, the latent and the active but undetected, excluding the confirmed/quarantined on prior days. the theoretically detected new shows the analytical relationship of the daily confirmed cases to the total infected population. observed new is the daily confirmed cases in the public report. the following result becomes obvious. if we use ∆ n as the theoretically detected new on day n, clearly one can reach the following result, combining equations ( ) and ( ), we get a major result as illustrated in the following equation. again, p i is an outcome of a random variable at a constant (average) rate during a stable epidemic period. to simplify, one may simply assume that p n and p n+ just represent their expected value. within two consecutive days, if there are no dramatic changes to the sampling methods and regulating policies for detecting the infected cases, one may assume p n ≈ p n+ , which explains the approximation in equation ( ) above. observation when the newly confirmed cases stay flat from day n to day n + , the total infected cases on the two consecutive days may be deemed to roughly stay flat. again, the total infected population on day i mentioned in observation excludes the detected and quarantined on prior days. observation is trivial in the sense that an equal number of newly confirmed cases and an equal probability of detection naturally allude to an equal size of infected populations on two days. the above discussion also implies: our interest is in estimating the total infected population at the end of a day, the vast majority of whom are the undetected, active and latent infections. let take a look at a special case, which is roughly true in the u.s. today, where n n+ nn ≈ . . in this case, we have ( − p n )( + r n ) ≈ . , on which much the discussion ensued is based. we summarize the basic result here. the sufficient and necessary condition to keep an epidemic from growing is to satisfy the following condition: when ( ) is in equality, the epidemic reaches an equilibrium, meaning the total hidden plus newly confirmed remain a stable population. as a special case, at low infection rates such as during shelter-in-place, the required detection rate of the infected is roughly equal to the infection rate in order to control the total infected population from growth. one knows, with social distancing and shelter-in-place orders, ( + r n ) remains very low and yet above . as one may assume safely for the nation. then one can roughly estimate the detection probability p n needed. proposition is intuitive and obvious. if ( + r n ) is very close to . from values above . , one may say that p n is close to zero from values also above zero when a stable trend of daily confirmed cases is observed. if p n is very close to zero, in a conservative estimation, say p n ≈ . , the total hidden infected population would be about times larger than the latest average daily confirmed amount. the closer ( +r n ) is to . , the closer p n is to zero, and the larger the total infected population compared with the stable daily confirmed cases. note that in our simple discussion here, it is impossible to separate the effect of r n with p n in the growth ( + r n )( − p n ). therefore, we have no certainty about the values of p n and r n respectively. researchers can only conduct additional studies in order to have separate estimates of the two variables. for public information, there are several scenarios about the guess at the total hidden cases, ranging from the most conservative to the most aggressive. note that these guesses of the infected total on the day (excluding prior confirmed) is under the circumstance of having flattened new cases each day. • conservative in this case, we assume a growth rate r n to be as reasonably large as possible. in a scenario in which each patient infects . others during an active period of days, the daily infection rate appears to be . = . , meaning r n = . . in this case, if the total new confirmation remains relatively stable, implying ( − p n )( + r n ) ≈ . , p n ≈ . , the total active cases of infection on that particular day would be nn pn ≈ . n n . • moderate in the case that the infection rate, under fairly strict social distancing and shelter-in-place practices, has dropped to a third of that under the normal unrestricted social life as above, where ( + r n ) ≈ . , ( − p n )( + r n ) ≈ . reveals p n ≈ . , implying nn pn = . n n is the total infected on day n. • aggressive this scenario is one that practices very stringent social distancing and shelter-in-place orders, let's assume that the infection rate is controlled to a tenth of the rate for the unrestricted case, meaning ( + r n ) ≈ . . in this scenario, if the total new confirmations each day remains flat (hypothetically), the equation ( − p n )( + r n ) ≈ . alludes to p n ≈ . . this means that the total infections in the population on day n is nn pn ≈ . n n . the above example scenarios, all assuming the epidemic is under control by having the total newly confirmed cases flat over a period of days, indicate a large number of currently active and latent infections in the population ranging from to / times of the daily confirmations. today, the daily confirmation within the u.s. has been in the range of twenty to thirty thousand cases. our simple result suggests that the total current infections in the communities, excluding the quarantined, probably would be in the range of . to . million. in the case that schools and businesses are reopened in the near future, where people reasonably practice social distancing and follow other published preventive guidelines, a new situation between the conservative and moderate scenarios listed above, if the new infection has flattened out or has reached a new equilibrium, the total hidden infections alive on the day would reasonably be in a range of - times the daily confirmed cases. of course, the daily confirmed cases after reopening is expected to be higher than under shelter-in-place. with reopening, the infection rate r n would be larger than when the shelter-in-place was enforced, probably by a few hundred percentage. the growth rate likely will be kr where k ≥ if we use r for the growth rate during shelter-in-place. in order to have the total infected population non-increasing to form a new equilibrium, in light of equation ( ), the newly confirmed cases shall not increase from day to day based on the average trend, which roughly means n n+ nn ≈ . . note that under shelter-in-place, one roughly has r i ≈ p i on day i, which corresponds to an equilibrium condition ( + r) × ( − p) ≈ . , where p represents the stable detection rate during shelter-in-place. under business reopening, ( +r n )( −p n ) = ( +kr)×( −mp) is the new infection growth rate, where mp is the new detection rate required to control the infected population from growing, and m ≥ . . if we have m ≈ k, we would have ( +r n )( −p n ) = ( +kr)×( −mp) ≈ ( +r)×( −p) ≤ . . the above logic assumes p n and r n are both small and that p n r n ≈ . to summarize, the following result appears to hold by itself. proposition in a switch from shelter-in-place to business re-opening, to prevent the infected population from growing, if the infection rate becomes k times larger, the probability of having the infected to be detected shall be about k times larger accordingly. what does this larger detection probability mean? with social distancing and shelter-in-place, a low infection rate allows an equilibrium with a low detection rate, which is a balance between the new infections (recovery and death are considered a negative increase) and the ones quarantined. with business re-opening, the infection rate would probably spike, say by k times, if the proportion of the population being checked or sampled (or an equivalent of it) remains unchanged as under shelter-in-place, the infected population would explode. the rate of explosion, in light of the discussion at the beginning of this subsection, would be ( − p n )( + r n ) ≈ + (k − )r. there will be no equilibrium between the newly infected and the newly detected if the detection rate falls behind the infection rate. the practical meaning of this observation may be recapped as follows. we do not have a specific value for the daily infection rate r n before and after the business re-opening, which needs to be specially studied by professionals. with business re-opening, if the chance of detecting an infected is not keeping pace precisely with the infection rate increase, the infected population will keep growing. worthy of a note is that the detection rate here is the probability of a random infection in the community to be tested based on some mechanism (such as social contact tracing, body temperature check at some key locations, random sampling in the communities, etc.). this report is not in a complete agreement with some media reports such as [ ] , which advocates for an absolute increased total number of tests. we think the sample rate or its equivalent is the factor effective to epidemic control. it's about the percentage of the people who shall be tested and quarantined, not the absolute number. again, stringent social contact tracing is an effective means to raise the percentage of infections to be quarantined. in this section, we briefly summarize the current strategies in dealing with covid- . the previous section makes it clear that to put the epidemic under control, one must have inequality ( ) satisfied. at the very minimum, ( ) shall be an equality. all the measures so far undertaken by governments and other entities fall into two categories: controlling the infection rate and controlling the detection rate. • containing the infection rate the measures in this category include: shelterin-place, specially social distancing, quarantine policy, all means of disinfection or sanitation, medical treatment, etc. immunization as the final solution may be considered as a special means, • improving the detection rate this category includes social contact tracing, population sampling, test kits of improved accuracy, additional means such as quick antibody test, body temperature measurement as a pre-screening means for virus test, etc. it appears that much more can be done at the front of increasing detection rate. the difficulty is in the fact that to identify an infected resembles a witch hunt due to the randomness or uncertainty. google and apple are reported working together to develop social media applications for (voluntary) tracing social contact and for alert of potential danger of infection, which serves both purposes of reducing infection and increasing detection rates [ , ] . contact tracing of an infected person remains a valid means. if contact tracing is effective, it equivalently increases the detection rate and decreases the infection rate simultaneously. stringent contact tracing is a proven means in other countries such as south korea. as mentioned shortly above, the public body temperature measurement through automatic machines when the public pass through key locations may prove to be an extremely beneficial means to greatly increase the detection rate of the infected. here, we propose a sampling method as an additional but not a substitute means to the existing measures. in light of condition ( ), a sample rate that is equal to the infection rate, or other means such as very stringent social contact tracing that achieve an equivalent effect, would work. we mean here for a random sampling of the public. this random sampling may also be coupled with enhanced contact tracing of the community or social groups of newly confirmed infections. we propose a stratified sampling by prioritizing the high-risk groups. there are statistics in the u.s. to show different infection rates for population strata according to ethnicity, age, or other criteria ([ ] [ ] ). if the sampling cost is too high, a low-cost screening process may be first implemented such as a temperature check. temperature check at major traffic locations such as airports and subway stations is an effective pre-screening means. we propose a sample rate proportionate to the infection percentage of the strata weighted by the varying costs, one of the costs being life-threat. obviously, the aged groups, especially those with complications, have a more severe consequence from the infection. to understand the necessity of sampling in public, one might consider such a question: would social contact tracing alone meet the needs of control without sampling of the population? vast deployment of body temperature measurement machines is an example of large population sampling. there may be a debate here. but in our view, periodic sampling to a certain extent, preferably on a daily basis, is necessary to an enhanced social contact tracing. consider social networking in the context of covid- . figure illustrates this general idea. this social network (via proximity connection) contains the most effective entities in terms of spreading the virus. an individual may be an entity shown as a string that connects multiple dots (or nodes). an entity may be a household in which the household members are considered fully communicated internally in terms of virus infection. a string accounting for a household (e.g. the connected links of the network) may be connected to many other nodes such as shopping malls, schools, plants, etc. there are also nodes that many entities traverse. nodes and strings all have varying attributes that contribute to the virus spread to different degrees. schools, including k- and college education when face-to-face classes are resumed may be considered high-risk nodes. families of active members exposed to close contact with a large number of others are also considered as strings with large weight. the goal of dealing with this network is to identify the nodes and strings that may effectively circumvent the spread of covid- . although much needs to be studied in future through the academic community regarding covid- spread, much can now be done by governments and people in their responsible positions. these include: identify critical locations with most social connections, identify entities that connect most critical locations (e.g. household with multiple members working at shopping malls, factories, attending schools simultaneously). a major job of the governments and administrations would be to implement measures that impede or this is a preliminary discussion of covid- spread in the process of test and quarantine. the main focus is about the general conditions needed to put the epidemic under control, a situation in which the total infected population size does not grow or even shrink. the results are intuitive and straightforward. this document may, therefore, serve as an educational material to the public or the government officials in positions relevant to disease control. the major finding is that the effective detection rate should keep up in pace with the infection rate such that ( + r)( − p) ≤ . . this finding implies that the detection rate under business re-opening shall keep pace with the expectedly spiking infection rate. this discussion has touched on the means in two categories, detection and infection rates control, respectively. enhanced social tracing may be an effective means of increasing the detection rate. the detection rate here is the probability of a random infection in a community to be selected and tested for infection random sampling based on strata is also proposed, which emphasizes the strata likelihood and also strata severity of infection. a principle is that the sample rate shall be consistent with the strata infection rate weighted by infection consequence. note that direct sampling for infection test may turn out to be too costly. therefore, vast deployment of automatic body temperature measurement machines at key locations with large volume of traffic, especially traffic that risk transmitting virus among regions or communities is necessary as a pre-screening step of social sampling. another interesting finding is that when the daily confirmed cases remain relatively stable a trend, an equilibrium has likely formed between infection and detection. this means ( + r)( − p) ≈ . . under social distancing and shelter-in-place, the infection rate is low, and obviously, the detection rate p is low as well. one may estimate the total alive infections hidden out in the communities of up to times the daily confirmations. note that the same day total alive infections of times the daily confirmation is equivalent to a total cumulative infections of about times the cumulative daily infections. this estimate may serve as an alert to the policymakers when they prepare for business reopening. those undetected infections would incur a higher infection rate during business re-opening and require a higher detection rate accordingly. the needed higher detection rate would come from a heightened contact tracing system, which is desirably coupled with new community sampling practice. in fact, the infection rate and detection rate are both random numbers from day to day. therefore, the ratio between confirmed cases on two consecutive days may fluctuate around . , not stably equal to a constant . . the infection and detection rates may be taken as the expected values and be used for the trend analysis. if a model fully considers the randomness of the two rates, a reliable condition to control the epidemic is likely to be ( + r)( − p) < . − ǫ, where ǫ is a small positive number representing a little room to allow for the randomness and errors in the process. without further extensive studies, the two parameters used here, r and p, would not be known exactly. however, the relationship and the qualitative meaning of the results are sound. this discussion was driven by interest, it did not involve extensive, data rich effort which are often backed by projects. therefore, the limitations of this report are multitude. we hope this report may bring its audience to an operations research perspective for this epidemic control. coronavirus disease (covid- ): cases in the u covid- united state cases the effect of control strategies to reduce social mixing on outcomes of the covid- epidemic in wuhan, china: a modelling study interventions to mitigate early spread of sars-cov- in singapore: a modelling study pattern of early human-to-human transmission of wuhan real-time forecasts of the covid- epidemic in china from estimating and simulating a sird model of covid- for many countries, states, and cities. no. w why is it difficult to accurately predict the covid- epidemic? substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (sars-cov- ) incubation period and other epidemiological characteristics of novel coronavirus infections with right truncation: a statistical analysis of publicly available case data incubation period of novel coronavirus ( -ncov) infections among travellers from wuhan, china the incubation period of coronavirus disease (covid- ) from publicly reported confirmed cases: estimation and application early transmission dynamics in wuhan, china, of novel coronavirusinfected pneumonia pandemics explained: hghi and npr publish new state testing targets coronavirus phone tracing by apple and google could help america reopen. usa today, gannett satellite information network apple and google have a clever way of encouraging people to install contact-tracing apps for covid- . the verge, the verge using social network analysis to assess communications and develop networking tools among climate change professionals across the pacific islands region this study is a self-motivated effort with partial support from a e.b. snead ' career development professor i fund through the zachry department of civil and environmental engineering at texas a&m university. errors and mistakes are solely the authors'. key: cord- -clje b r authors: ghanam, ryad; boone, edward l.; abdel-salam, abdel-salam g. title: seird model for qatar covid- outbreak: a case study date: - - journal: nan doi: nan sha: doc_id: cord_uid: clje b r the covid- outbreak of has required many governments to develop mathematical-statistical models of the outbreak for policy and planning purposes. this work provides a tutorial on building a compartmental model using susceptibles, exposed, infected, recovered and deaths status through time. a bayesian framework is utilized to perform both parameter estimation and predictions. this model uses interventions to quantify the impact of various government attempts to slow the spread of the virus. predictions are also made to determine when the peak active infections will occur. coronavirus disease (covid-) (wu et al. ( ); rezabakhsh, ala, and khodaei ( )) is a severe pandemic a fecting the whole world with a fast spreading regime, requiring to perform strict precautions to keep it under control. as there is no cure and target treatment yet, establishing those precautions become inevitable. these limitations (giuliani, et al. ( )) can be listed as social distancing, closure of businesses and schools and travel prohibitions (chinazzi et al. ( )). corona virus is a new human betacoronavirus that uses densely glycosylated spike protein to penetrate host cells. the covid-belongs to the same family classi cation with nidovirales, viruses that use a nested set of mrnas to replicate and it further falls under the subfamily of alpha, beta, gamma and delta co-vis. the virus that causes covid-belongs to the betacoronavirus b lineage and has a close relationship with sars species. it is a novel virus since the monoclonal antibodies do not exhibit a high degree of binding to sars-cov-. replication of the viral rna occurs when rna polymerase binds and re-attaches to multiple locations (mcintosh ( ); fisher and heyman ( )). cases of covid-started in december when a strange condition was reported in wuhan, china. this virus has a global mortality rate of . %, which makes it more severe in relation to u. the elderly who have other pre-existing illnesses are succumbing more to the covid-. people with only mild symptoms recover within to days, while those with conditions such as pneumonia or severe diseases take weeks to recover. the recovery percentage of patients, for example, in china stands at %. the recovery percentage rate of covid-is expected to hit % (who ( )). the virus has spread from china to other countries and territories across the globe. from wuhan, hubei province, the virus spread to mainland china, thailand, japan, south korea, vietnam, singapore, italy, iran, and other countries. the state of qatar was one of the countries that were a fected by the covid-spreading and the rst infected case was reported on th of february and it could be considered the nd highest in the arab world with the number of con rmed cases , as of may , . for e fectively specifying such security measures, it is essential to have a real-time monitoring system of the infection, recovery and death rates. develop, implement and deploy a data-driven forecasting model for use by stakeholders in the state of qatar to deal with the covid-pandemic. the model will focus on infected, deaths and recovered as those are the only data available at this time. this document is organized in the following manner. in section the seird that is employed is de ned. next, section introduces the data available and gives description. then shows how interventions are incorporated into the model. the let s(t) be the number of people susceptible at time t, e(t) be the number of people exposed at time t, i (t) be the number of infected at time t, r(t) be the cumulative number of recovered at time t and d(t) be the cumulative number of deaths at time t. this can be modeled with the following system of ordinary di ferential equations: where α is the transmission rate from susceptibles to exposed, β is the rate at which exposed become infected, γ is the rate at which infected become recovered and η is the mortality rate for those infected. notice that, this model formulation makes several key assumptions: . immigration, emigration, natural mortality and births are negligible over the time frame and hence are not in the model. . once a person is in the infected group, they are quarantined and hence they do not mix with the susceptible population. . the recovered and deaths compartments are for those who rst are infected. there is no compartment for those exposed who do not become sick (infected) and recover on their own. traditional analysis would include a steady state analysis, however, in this case the dynamics of the short term is of interest. hence, this work does not address any steady state or equilibrium concerns. this work is concerned with tting the model given in ( ) to the covid-data concerning the state of qatar during the outbreak and using the model for forecasting several possible scenarios. the johns hopkins covid-github site includes for every country for each day the cumulative number of con rmed infections, cumulative number of recovered and the cumulative number of deaths for each day starting january . the data for qatar was obtained. notice that in model ( ) the recovered and death states are cumulative as once one enters the compartment their is no exit. however, the infected compartment has transitions from exposed and to recovered and deaths. hence the data provided for con rmed infections is cumulative and included both recovered and deaths and will need to be removed from this compartment's data. let ci (t) be the con rmed infections at time t and let infected i (t) be de ned as: for clarity the term "active infections" will be used to denote this derived variable versus the cumulative infected provided in the data. figure shows the plots of the active infections, recovered and deaths data for qatar for the days since february . notice that the active infections are very low until around day when there is large jump due to increased testing. the active infections then seems to plateau for until day , after which there is extreme growth in active infections. there seems to be a similar pattern for the recovered with a delay showing the time of infection before recovery. the plot for deaths shows no deaths until day and then a steady increase in deaths for the remaining days. the state of qatar, prepared an excellent exible plan for risk management, grounded on national risk assessment, taking account of the global risk assessment done by who, focuses on reinforce capacities to reduce or eliminate the health risks from covid-. embed complete emergency risk management strategy in the health sector. furthermore, enabling and promoting , closed all parks and public beaches to curb the spread of coronavirus. on march , (day ), the ministry of commerce and industry decided to temporarily close all restaurants, cafes, food outlets, and food trucks at the main public era. also, the ministry of commerce and industry decided to close all the unnecessary business on march , (day ) hamad medical corporation ( ) and mph-qatar ( ). these interventions taken by the government change the dynamics of the system and hence need to be incorporated into the model. the next section details how we introduce interventions both from the government and interventions guided by the data. in figure , one can see the jump at day and a plateau until day . the model needs to be able to handle interventions made by the government of the state of qatar. the main parameter that policy can in uence is α, the rate of transmission from exposed to susceptible. one way to implement this the use of indicator functions w k (t) de ned as: where t k is the time where the k th intervention is taken and index k = , , .., k . for each intervention there needs to be a change to the value of α, denoted α k , that captures the impact of the intervention. let the vector this formulation gives the following transitions rates between s(t) and e(t): which will require the following constraints due to the fact that α(t) > for all t: let be the set de ned by the constraints above. in addition to changes in infection rates α, impulse functions can be used to model dramatic one time shifts in transitions between states. a dirac delta function de ned by ). this can be integrated in the model to capture spikes in the number of cases. in our case the state of qatar data shows exhibits this type of behavior at day where one can clearly see a large jump in the number of infections. this is incorporated into the model presented by a dirac delta function, δ(t − τ), in transition rate between exposed and infected, which is coupled with a coe cient to β a to capture the impact of the jump. due to the complexity of the model the bayesian inferential framework is chosen. recall, bayes formula is given by (bayes and price, ) : where π(θ|d) is the posterior probability distribution for the parameters θ given the data d, π(θ) is the prior distribution of θ and l(d|θ) is the likelihood of the data given θ. in order to specify the likelihood of the model in equation ( ) the model modi ed to model the mean abundance in each compartment and is given by: and d(t), respectively and the parameters have the same de nition as provided in the system given in equation ( ). since there is no data for s(t) and e(t) these compartments will be latent variables and will not directly factor into the likelihood. the likelihood for i (t), r(t) and d(t) are given by: to specify the prior distributions for α, β a , β, γ and η one must incorporate the following constraints α > , β > , γ > and η > . hence the following prior distributions are set: where c ( ) is an indicator function takes the value if α ∈ . this serves to truncate the normal distribution in order to keep α in the feasible range of values. the likelihood and prior distributions speci cations lead to the following posterior distribution when a = and σ = : the posterior distribution does not lend to any analytic solution, hence markov chain monte carlo (mcmc) techniques will be used to sample from the posterior distribution (gelman et al., ) . speci cally metropolis-hastings sampler is used to obtain samples from the posterior distribution (gilks, richardson, and spiegelhalter, ) and (albert, (@) . to tune the sampler a series of short chains were generated and analyzed for convergence and adequate acceptance rates. these initial short chains were discarded as "burn-in" samples. the tuned sampler was used to generate , samples from π(α, β a , β, γ, η|d) and trace plots were visually examined for convergence and deemed to be acceptable. all inferences will be made from these , samples. the model and sampling algorithm is custom programmed in the r statistical programming language version . . . the computation takes approximately seconds using a amd a -. ghz processor with gb of ram to obtain , samples from the posterior distribution. for more on statistical inference see wackerly, mendenhall, and schea fer ( ), casella and berger ( ), and berger ( ). to apply the model the following initial conditions are speci ed: s( ) = , , , e( ) = , i ( ) = , r( ) = and d( ) = . here s( ) is the current population of the state of qatar, i ( ), r( ) and d( ) are obtained directly from the data. the choice of e( ) was used as it a minimal value that would allow the disease to spread but not so large as to make the spread rapid. several values of e( ) were explored and the value of was found to have the best t. furthermore, model interventions were placed at days t = , t = , t = , t = and t = with an dirac delta impulse at time τ = . table shows the means, standard deviations and the . %, . % and . % quantiles for the model parameters based on the , samples from the posterior distribution. notice that, α = . × − and α = − . × − are very close in magnitude with di ferent signs indicating that the rst intervention drastically reduced the transmission rate. similarly one can see that the second and third interventions α = . × − and α = − . × − essentially are of the same magnitude with di ferent signs which when added resulting in a very low transmission rate. however, α = . × − is a small increase with a moderate decrease in α = − . × − which still leaves a nal transmission rate of k k= α k ≈ . × − . of particular note is the mean mortality rate η = . ≈ / which means that about in , people perish from the disease each day, which is quite low. also note that the mean infection (con rmed) rate is β = . ≈ / . which corresponds to about in . exposed people become con rmed each day. the quantile intervals provide a % credible interval for the parameters and can be used to obtain a range of reasonable parameter values. for example for the parameter β the interval is ( . , . ) meaning that the probability that β is between ( . , . ) is . . this can be used to create an interval for the risk interpretations as between / . ≈ . and / . ≈ . exposed people are con rmed as infected each day. this also gives insight into how many people who may be in the population who are exposed and may be infectious but do not yet exhibit symptoms. recall that β a is associated with the dirac delta function for impulse to model the jump in transition rate from exposed to infected at day . notice that β a ≈ . means that there is a one time in ux of approximately . % of the people exposed moved to the infected compartment. hence the increased testing captured many of the exposed people. by adding this to the natural exposed to infected rate of β = . one obtains the one time transmission rate of β + β a = . + . = . corresponding to a total of approximately . % of exposed being con rmed as infected. leaving the remaining approximately . % of exposed people still interacting with the susceptible population. while many of the parameters do not lend well to the traditional h : θ = hypothesis testing as they must be positive. we can conduct simple hypothesis tests on the α parameters to look for signi cant changes due to interventions using contrasts. speci cally the sequential contrasts of α − α , α − α , α − α , α − α and α − α . these contrasts quantify the changes that in transmission rate from susceptible to exposed due to the interventions and are what policy makers want to see. furthermore, they want a statistical test on whether or not the intervention performed in a statistically signi cant manner. this can be done by simply subtracting the mcmc samples to generate the contrast of interest. using these subtracted samples one can look at the mean, standard deviation, quantiles and the proportion of samples above , p(> ). table shows these quantities for the contrasts listed above. notice that the intervention at day reduced the transmission rate by approximately . × − ) which is considerable and the proportion of samples above was . indicating a statistically signi cant change due to the intervention. the intervention taken at day , α − α , actually increased the transmission rate, where the intervention taken at day , α − α , then reduced the transmission rate. similarly the other two interventions increased and then decreased the transmission rates, respectively. furthermore, all interventions be deemed statistically signi cant since p(> ) is either . or . indicating signi cance. the model formulation also allows for the individual transmission rates to be computed by simply summing up the α k through to the desired time point. table gives the mean, standard deviation and (q . , q . , q . ) for the transmission rate of exposed to infected across each time interval. this is done by simply add the corresponding mcmc samples. this is another perspective on how the transmission rate changes across the time frame. notice that all of the transmission rates are positive which is required by the model speci cation. also notice that the mean transmission rates vary in orders of magnitude from . × − to . × − . one interesting point that should be made is the highest transmission rate is at the beginning and the lowest transmission rate is at the end. this is evidence that the interventions that the qatari government has ultimately reduced the transmission rate. to assess the t of the model the posterior predictive distribution was used and is given by: using the samples , samples from the posterior distribution , samples were generated from the posterior predictive distribution. at each time t the median, . and . quantiles were obtained to form a posterior predictive interval. figure shows the model ts for active infections, recovered and deaths with posterior predictive bands. notice that, the model does quite well at tting the dynamics of the active infections including the jump at day and captures the plateau and the exponential growth after the plateau as well. the recovered model does ts well as does the deaths data. to assess the explained variance a pseudo-r was formed using the median from the posterior predictive distribution at each time as the point estimates. this resulted in a pseudo-r of . which indicates the tted model explains approximately . % of the variance in the data. based on this the model is deemed to t well. it should be noted that standard data splitting procedures for model validation are di cult in this scenario as removing values from the system may cause unstable behavior. to assess the model performance predictive performance is utilized with days from may and may used as a test set. using the samples from the posterior distribution the posterior predictive distribution was computed for each day of the test set and % posterior predictive intervals were created using the . % and . % quantiles. the test data is then compared to the posterior predictive intervals for each of the endpoints. another view of predictive performance is to examine pseudo-predictive-r which compares the predicted values with the actual values for the test set. this calculation leads to a pseudo-predictive-r ≈ . which is slightly lower than the pseudo-r associated with the t of the model to the data in the training set but is still very high. of course several other measures of predictive performance exist however this is the easiest to understand as it measures the amount of variation explained by the predictions across the test set. this work has demonstrated how to build a seird model for the covid-outbreak in the state of qatar, include interventions, estimate model parameters and generate posterior predictive intervals using a bayesian framework. furthermore, the model is able to treat the susceptible and exposed compartment as latent variables, as no data is observed about them other than approximate initial values. the model ts the data quite well with a pseudo-r ≈ . and predicts reasonably well with pseudo-predictive-r ≈ . . one can also note that in the model de nition, no immigration, emigration, natural births and natural mortality were not included and based on the high psuedo-r would have a negligible e fect on t. furthermore, the model did not contain compartments for those who recovered without being con rmed infections. as this was not observed one can only speculate on the impact that additional data would have on the model t, however it would be very small. the modeling paradigm is quite exible for modeling the covid-data as it easily incorporates interventions into the system and can quantify the impact of the intervention. furthermore, using simple di ferences the model can be used to predict new infections as well. figure shows the plots of the new infections with predictive bands based on . % and . % based on , samples from the posterior prediction distribution at each time point. notice that the model does well at capturing the jump at day and the bands capture most of the data. the drop beginning at the intervention at day provides for the drop in daily infection rates. another use of the model may be for long term predictions. while this is extrapolation it does provide policy makers a tool for planning, provided nothing changes, i.e. no interventions are taken. it also allows policy makers to see the possible long term e fects of their decisions. figure shows the long-term predictions of the model if no other interventions are made past may . notice that the predictions do eventually decrease across the future time frame. notice the width of the predictive bands for times farther in the future. this re ects the uncertainty associated with extrapolating into the future. however, one item that we can calculate from this is a % predictive interval for the peak infection time. by simply recording the maximum value for each of the predictive distribution trajectories from the mcmc samples one can obtain a distribution of the time for the maximum. in this case this gives the % predictive interval for the maximum to be ( , ). this means that the peak infection time will be between day ( june ) and day ( august ) of the outbreak given that no other interventions or process changes occur. fig. also shows this interval given by the dark dashed vertical lines. the width of the interval quanti es the uncertainty about where the maximum active infections will occur. since the width of the interval is days, this indicates that there is a large amount of uncertainty on when the number of active infections will begin to decline. future work could be to add an overdispersion parameter into the model to allow for the more accurate capture of uncertainty. furthermore, one can perform simulation studies to better understand how the model may perform under various scenarios. feature selection methods could be employed to select where the interventions should be placed as well as other forms of interventions could be included in the model. another possibility to address any deviations from the standard model a semi-parametric technique could be studied as well. quantiles from , samples from the posterior predictive distribution. dark dashed vertical lines give the % predictive interval for the maximum active infections. australian health sector emergency response plan for novel coronavirus (covid-) qatar national preparedness and response plan for communicable diseases. doha, qatar. primary healthcare corporation covid-strategic preparedness and response plan operational planning guidelines to support country preparedness and response an essay towards solving a problem in the doctrine of chance. by the late rev. mr. bayes, communicated by mr statistical inference, nd edition markov chain monte carlo in practice bayesian computation with r: second edition statistical decision theory and bayesian analysis, second edition the principles of quantum mechanics, fourth edition the authors would like to acknowledge to the state of qatar and the ministry of health for the daily updates and additional data. in addition the authors would like thank virginia commonwealth university in qatar and qatar university for supporting this e fort. key: cord- -lysrwv f authors: stock, james h; aspelund, karl m; droste, michael; walker, christopher d title: estimates of the undetected rate among the sars-cov- infected using testing data from iceland date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: lysrwv f testing for sars-cov- in the united states is currently targeted to individuals whose symptoms and/or jobs place them at a high presumed risk of infection. an open question is, what is the share of infections that are undetected under current testing guidelines? to answer this question, we turn to covid- testing data from iceland. the criteria for testing within the icelandic medical system, processed by the national university hospital of iceland (nuhi), have also been targeted at high-risk individuals, but additionally most icelanders qualify for voluntary testing through the biopharmaceutical company decode genetics. we use results from iceland's two testing programs to estimate the share of infections that are undetected under standard (nuhi) testing guidelines. because of complications in the decode testing regime, it is not possible to estimate a single value for this this undetected rate; however, a range can be estimated. our primary estimates for the fraction of infections that are undetected range from . % to . %. with covid- or have been traveling, initially in high-risk areas-mostly ski areas in italy and austria-and later anywhere abroad. quarantines last days or until the individual develop symptoms and are tested positive for sars-cov- by nuhi. at its peak, about , icelanders were under quarantine. the presence of these two testing programs makes it possible to draw inferences about the rate of infections in iceland that are undetected under the nuhi testing guidelines. because the nuhi testing guidelines are similar to those recommended by the centers for disease control and prevention (cdc) in the united states, an estimate of the rate of undetected infections can inform epidemiological modeling in the united states. estimates from the icelandic population complement other estimates of the rate of undetected cases among the infected (li et. al. ( ) , mizumoto et. al. ( ) , nishiura et. al. ( ) , russell et al. ( ) ; see qui ( ) ). we are interested in the fraction of the infected who are not eligible for nuhi testing (the "undetected rate"). expressed as a probability, this rate is pr( = | = ), where ne = if the individual is eligible for nuhi testing (nuhi-eligible) and otherwise (nuhi-ineligible), and i = if the individual is infected with sars-cov- and otherwise. denote this rate by θ. using bayes law, the undetected rate is related to the rates of infection among the nuhi-eligible and the nuhi-ineligible: ( ) is the total infection rate. if the (a) fraction of the population that were nuhi-eligible on a given day were known and if (b) decode testing was a random sample of the nuhi-ineligible, then the first expression in ( ) could be evaluated directly using data on the nuhi positive testing rate, pr( = | = ), and the rate of infection among the nuhi-ineligible, ( ) . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https: //doi.org/ . //doi.org/ . / the source of problem (a) is that, while the number of nuhi tests on a given day is known, the number of individuals who would qualify for a nuhi test is not. if all those who qualify for a nuhi test are referred to nuhi for testing, then they will get tested at some point, but on any given day only some of those eligible are tested. our first approach to addressing the nuhi stock/flow issue (a) is to estimate the probability of nuhi-eligibility, ( ) pr ne = , as the fraction of the icelandic population tested during an -day window, where the days aligns with the data window reported in guðbjartsson et al ( ) . we refer to this as the "eligibility window" method. our second approach to addressing problem (a), which we refer to as the "odds ratio" method, is to use the laws of probability and algebraic manipulation to eliminate the probability of nuhieligibility from the expressions above. doing so, however, introduces a new parameter, which is the baseline rate of cough/cold/flu symptoms that are severe enough to qualify for a nuhi test, even though the individual turns out not to be infected. this baseline symptomatic rate can be estimated using historical data on flu cases in iceland. it is shown in the appendix that the bayes law expression ( ) and its counterpart for the nuhi-eligible imply, equation ( ) express the undetected rate, θ, in terms of ne f , ni f , and λ , so if those three terms can be estimated, then θ can be estimated using ( ). the term f ne can estimated directly from nuhi testing data, and the term λ can be estimated by the proportion of icelanders who see a doctor about flu-like symptoms, see appendix section b for more details. both the eligibility window method (equation ( ) and the odds ratio method (equation ( )) require an estimate of ni f , the fraction of infections among the nuhi-ineligible. if the decode sample were a random sample of the nuhi-ineligible population, this would be estimated by the nuhi positive testing rate. however, the decode sample has two complications: it was voluntary, and those in quarantine were excluded. the next two sections discuss these issues turn, and show how the decode positive testing rate can be used to bound ni f that accounts for the complications in the decode testing sample. for the eligibility window method, we thereby estimate a lower bound (a conservative estimate of θ), and for the odds ratio method we are able to estimate both a lower and upper bound. because decode testing was voluntary during the time period analyzed here, it could overrepresent those who suspect they have the virus but are nuhi-ineligible. approximately % of individuals tested by decode exhibit cold/flu symptoms (guðbjartsson et al, , table ) , . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint much higher than the historical prevalence of cold/flu symptoms in iceland. we will refer to these % as "mildly symptomatic." as a result, the decode positive testing rate could overestimate the true fraction of infected among the nuhi-ineligible. to address this problem, note that ni f is a weighted average of the infection rates among the mildly symptomatic and the asymptomatic. under the assumption that the asymptomatic and mildly symptomatic decode subsamples are randomly drawn from the asymptomatic and mildly symptomatic populations, respectively, then ni f can be estimated as the weighted average of these two (known) decode positive testing rates. although the rate of mild symptoms among the nuhi-ineligible is not observed, we bound it below by λ (the rate of severe flu symptoms in a normal march) and bound it above by the % of mild symptoms among the decode testing volunteers. see appendix section b for details. individuals in quarantine were excluded from decode testing and while some of the quarantined qualified for nuhi testing, some did not. infections among those quarantined but nuhi-ineligible are therefore not detected by either the nuhi or decode testing. under the assumption that the infection rate among the nuhi-ineligible quarantined does not exceed the infection rate of among nuhi-eligible, it is possible to use the laws of probability to bound the overall rate of infection among the nuhi-ineligible in terms of the infection rate among the nuhi-eligible and the decode rate (infections among the nuhi-ineligible who are not in quarantine). see appendix section b for details. we use data released by icelandic public health authorities on the covid- pandemic and on normal flu seasons. the icelandic directorate of health releases daily counts of new confirmed cases and tests conducted on its covid- information website. we use these data where possible. however, infection rates for individuals with no vs. mild symptoms are only available in the results by guðbjartsson et al ( ) , who report infection and test counts by symptom status for decode testing between march and . we therefore focus on this time period when calculating parameters for the bounds. only the most updated quarantine counts are available on the covid- website, so we use daily announcements by the icelandic department of civil protection and emergency management to find past quarantine totals in the bound analysis. to estimate the underlying prevalence of mild and severe flu-like symptoms, we use data from the directorate of health's website on influenza containing weekly counts of individuals who come english: https://www.covid.is/data icelandic: https://www.covid.is/tolulegar-upplysingar . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . to clinics or emergency rooms with flu-like symptoms for every flu season from the - through the - flu season (the most recent season available). appendix section b contains the details on the data and construction of estimates. the results are summarized in table . the primary estimate of the lower bound using the eligibility window method uses the infection rate among the asymptomatic from the decode tests and assumes that none of the nuhi-ineligible quarantined are infected; this yields an undetected rate of . % ( % confidence interval . % to . %). the second line re-estimates the lower bound using the overall decode positive testing rate, which includes the mildly symptomatic; because the mildly symptomatic have a somewhat higher decode positive testing rate than the asymptomatic, the estimate of the population infection rate is somewhat larger and the undetected fraction is somewhat larger, . %. as discussed, the nuhi testing eligibility guidelines were broadened after march , and using data postdating this broadening results in slightly lower estimates of the undetected rate, approximately %. for the odds ratio estimate, we estimate λ by the maximum weekly caseload for flu-like symptoms in the icelandic medical system for all weeks from to . this highest-caseload week occurred in november at the peak of the h n pandemic and was . %. the resulting estimated range is consistent with the estimates from the eligibility window method, with a range of . % to . %. the fraction of infections that are undetected under standard current testing guidelines is differs from the asymptomatic rate, which is the fraction of infected who are asymptomatic. because the nuhi-ineligible include those who are mildly symptomatic, it is not surprising that the estimated nondetected rate exceeds estimates of the asymptomatic rate in the literature (mizumoto et. al. ( ), nishiura et. al. ( ). our estimate of the undetected rate is comparable to li et. al ( ) 's % estimate for wuhan. one threat to the validity of these estimates is that they assume that the decode testing of the asymptomatic is a reliable estimate of the rate of infection among the asymptomatic in the icelandic population. because decode test recipients did not meet the quarantine requirements (returning from high-risk countries or close contact with a confirmed covid- individual), this assumption seems plausible; it cannot be evaluated with existing data, however. data to provide unbiased estimates of the undetected rate, and the overall rate of infection in the population, need to come from random testing. such trials are commencing in iceland, germany, and norway. if a random testing design excludes those eligible for tests under medically-based guidelines and/or those in quarantine, the combined data sets could be analyzed using the methods laid out here. only in icelandic: https://www.landlaeknir.is/servlet/file/store /item /influensulik.einkenni.uppfaersla.a.vef. okt .ag.xls_%c %a n% myndar% og% aldursdreifingu.xls . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https: //doi.org/ . //doi.org/ . / . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https: //doi.org/ . //doi.org/ . / ( taking the ratio of odds ratios, we obtain that and by rearranging, = + . the bounds for arise because of the overrepresentation of mildly symptomatic in the (voluntary) decode sample and the exclusion of quarantined individuals from the decode sample, some of whom are not nuhi-eligible. the available information, however, provides bounds on . we make the following assumptions: . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https: //doi.org/ . //doi.org/ . / evaluating ( ) at the extremes of the range for and taking the resulting extremes for θ yields the identified set for θ. . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . see the text and appendix a for definitions of the various terms. • population: statistics iceland estimates that the population of iceland was , on january , . • : from the directorate of health's counts, we calculate the total count of nuhi infected cases and divide by the total count of nuhi tests from march through march , to match the decode testing dates. • : we use directorate of health weekly influenza count data to estimate λ by the greatest one-week fraction of icelanders reporting flu symptoms. this period occurred in november during the h n pandemic and was . %. to bound the proportion mildly symptomatic, we use a lower value of λ which is the average rate of reported flu symptoms in the two-week period around march from - , which is . %. • ( | = , = , = ), ( | = , = , = ): under the assumption that decode randomly tests within the decode-eligible symptomatic and asymptomatic groups, then these terms are estimated by the decode positive testing rates within these two groups as reported in table of guðbjartsson et al ( ) for decode testing from march through march . • ( = | = , = ): as a lower bound, we use the lower bound of λ of . %. as an upper bound, we use the proportion symptomatic from guðbjartsson et al ( ) , %, which reflects the assumption that mildly symptomatic individuals will be oversampled in the voluntary decode testing. • ( = ): the covid- website only reports the most updated count of individuals under quarantine, but we require the proportion not quarantined ( = ) at the time of testing. we use the number of quarantined individuals on march , the last day of decode testing reported in guðbjartsson et al ( ) , from the report of the department of civil defense on march . • ( = ) (for use in bounds calculation, odds ratio approach): we sum the number of nuhi tests from march through march from the health directorate count data to match the timing of the decode testing and the quarantine count figure in the bound analysis, then divide this sum by the population of iceland. early spread of sars-cov- in the icelandic population substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (sars-cov ) estimating the asymptomatic proportion of coronavirus disease (covid- ) cases on board the diamond princess cruise ship estimation of the asymptomatic ratio of novel coronavirus infections (covid- )," forthcoming covert coronavirus infections could be seeding new outbreaks key: cord- -jtv jmkn authors: wang, lin-fa; walker, peter j.; poon, leo l.m. title: mass extinctions, biodiversity and mitochondrial function: are bats ‘special’ as reservoirs for emerging viruses? date: - - journal: curr opin virol doi: . /j.coviro. . . sha: doc_id: cord_uid: jtv jmkn for the past – years, bats have attracted growing attention as reservoirs of emerging zoonotic viruses. this has been due to a combination of factors including the emergence of highly virulent zoonotic pathogens, such as hendra, nipah, sars and ebola viruses, and the high rate of detection of a large number of previously unknown viral sequences in bat specimens. as bats have ancient evolutionary origins and are the only flying mammals, it has been hypothesized that some of their unique biological features may have made them especially suitable hosts for different viruses. so the question ‘are bats different, special or exceptional?’ has become a focal point in the field of virology, bat biology and virus-host co-evolution. in this brief review, we examine the topic in a relatively unconventional way, that is, our discussion will be based on both scientific discoveries and theoretical predictions. this approach was chosen partially because the data in this field are so limited that it is impossible to conduct a useful review based on published results only and also because we believe it is important to provoke original, speculative or even controversial ideas or theories in this important field of research. lin-fa wang , peter j walker and leo l m poon for the past - years, bats have attracted growing attention as reservoirs of emerging zoonotic viruses. this has been due to a combination of factors including the emergence of highly virulent zoonotic pathogens, such as hendra, nipah, sars and ebola viruses, and the high rate of detection of a large number of previously unknown viral sequences in bat specimens. as bats have ancient evolutionary origins and are the only flying mammals, it has been hypothesized that some of their unique biological features may have made them especially suitable hosts for different viruses. so the question 'are bats different, special or exceptional?' has become a focal point in the field of virology, bat biology and virus-host co-evolution. in this brief review, we examine the topic in a relatively unconventional way, that is, our discussion will be based on both scientific discoveries and theoretical predictions. this approach was chosen partially because the data in this field are so limited that it is impossible to conduct a useful review based on published results only and also because we believe it is important to provoke original, speculative or even controversial ideas or theories in this important field of research. bats (order chiroptera), one of the most abundant, diverse and geographically dispersed vertebrates on earth, have recently been shown to be reservoir hosts of a number of emerging viruses responsible for severe disease outbreaks in humans and livestock [ , , ]. the first recognition that bats are involved in the ecology of human disease came during the s when rabies virus was identified in bats in south and central america [ ] . however, the discovery of henipaviruses in the mid- s and the subsequent recognition that bats may be a natural host of sars-like coronaviruses and filoviruses marked a new era of fresh research into the role of bats as an important reservoir host of viruses which have the potential to cause disease in humans and livestock [ , [ ] [ ] [ ] [ ] [ ] . the recent surge of interest in bats as a reservoir of viruses was driven by two factors. first, in less than years, several high profile viral pathogens have been proven or hypothesized to have a bat origin. since hendra virus was first discovered in , there have been at least known spillover events in australia with a mortality rate in humans of approximately % [ ] . the closely related nipah virus has been responsible for devastating disease outbreaks in malaysia, bangladesh and india with mortality rates ranging from % to %, resulting in the deaths of approximately humans [ ] . filoviruses (ebola and marburg viruses) have caused outbreaks in africa with associated human mortality rates as high as %, and have been linked to mass gorilla die-offs, making them both a public health and conservation concern [ ] [ ] [ ] . the outbreak of severe acute respiratory syndrome (sars) in - , due to a previously unknown coronavirus, resulted in more than human infections with a mortality rate close to % and an estimated cost of $ billion in lost tourism and trade [ ] [ ] [ ] . the association of these high profile pathogens and disease outbreaks with bats has led to an increase in public interest, funding and research activities on these and many other bat-borne viruses. however, it should be emphasized that, although closely related sars-like coronaviruses have been detected in horseshoe bats, the exact natural reservoir of the coronavirus responsible for the sars outbreaks is still unknown [ , ] . the true natural reservoir of ebola virus is also still being debated as rodents, insectivores and bats have all been identified as potential sources of infection in primates [ , ] . the second driver for the recent surge in bat virus research has been advances in modern molecular techniques which have presented opportunities for discovery of novel bat viruses, that were considered impossible or nonpractical just a decade ago. using pan-virus-specific primers and next-generation sequencing, it is now possible to detect and characterize novel viral sequences without the need for virus isolation by cell culture or the identification of virions by electron microscopy. numerous publications in the past few years have reinforced the observation, first made by sulkin and allen in [ ], that bats carry a wide range of novel rna and dna viruses. these results also provide support to the notion, as first observed during the investigations of bat coronaviruses (see below), that bats within a geographic location and/or taxonomic group have an unusual ability to harbor a large number of genetically diverse viruses. more recently, two metagenomic studies on bat fecal samples have revealed a great number of novel bat viruses, some of which have moderate sequence identity to previously known mammalian viruses, including members of the parvoviridae, circoviridae, picornaviridae, adenoviridae, poxviridae, astroviridae, herpesviridae and coronaviridae [ , ] . further systematic surveillance will be required to determine whether bats are the natural hosts of these novel viruses, but these results clearly indicate that there are many bat viruses yet to be identified. interestingly, similar to other metagenomic analyses of human or other animal fecal samples, these studies have also identified numerous sequences derived from viruses infecting insects, plants and bacteria. although these viruses are unlikely to infect bats, one might hypothesize that they could play an important role in facilitating the dispersal of these viruses to different geographical locations and different hosts. the high detection rate and great genetic diversity of viral sequences from bats have not only propelled further scientific and public interest in this field, but also led to debate on the importance of bats as reservoirs of zoonotic viruses. the question 'are bats different?' has been raised at many international conferences and has been the topic of several previous reviews [ , , , ]. while the currently available data are too limited to provide a conclusive answer, this review aims to examine different hypotheses which may eventually allow us to resolve this intriguing and fundamentally important question. it should be noted, however, that some of the discussions presented in this review are largely speculative or even controversial. this has been done intentionally by the authors to invigorate discussion and further research on this topic. bats have several features that might help to explain the seemingly high rate of virus detection. bats constitute the second largest order of mammals. there are about bat species worldwide, which represents more than % of all mammalian species [ ] . bats are classified in the order chiroptera in which there are two suborders: the yinpterochiroptera (also known as megachiroptera), which contains the megabats, and the yangochiroptera (microchiroptera), which includes the majority of microbat families [ ] . the wide range of bat species could provide a large 'breeding ground' for viruses. the earliest known bat fossil dates to . million years ago (mya) [ , ] . extrapolation of fossil records and genetic data has suggested that the basal split from other placental mammals in the superorder laurasiatheria occurred during the late cretaceous period approximately - mya, with extensive diversification of extant bat families commencing approximately mya [ ] [ ] [ ] . bat viruses may therefore have co-evolved with or adapted to bats over many millions of years. besides, bats are the only mammalian species that can fly and some bat species can migrate hundreds of miles to their overwintering or hibernation sites [ ]. thus, bats have more opportunities than terrestrial mammals to have direct or indirect contact with other animal species at different geographical locations, thereby enhancing the opportunity for interspecies virus transmission. in addition, some insectivorous bats exhibit exceptionally long life-spans of - years and live in panmictic populations comprising of millions of individuals. the long life-span of bats may facilitate the transmission of chronic persistent infections, whereas the unusually large and complex structure of bat populations may ensure a sufficient number of immunologically naive juveniles for bat viruses to persist in bat colonies. some bat species also have a capacity for hibernation over winter or to enter into daily torpor to conserve energy. the reduced body temperature and metabolic rate may suppress robust immune responses and reduce the rate of virus replication, thereby delaying virus clearance from bat populations [ , ]. purely a numbers game: more bat species = more viruses? in one of the most comprehensive reviews on bat viruses, calisher et al. [ ] listed different bat viruses that have either been isolated or detected. since then, many more novel bat viruses, as well as variants of previously known bat viruses, have been reported. in total, virus families - families of rna viruses and five families of dna virus -are known to infect bat genera [ ] . the detection rate of novel viruses or viral sequences appears to have been higher in bats than that in any other mammalian species for the past two decades or more. it could be argued that, as bats represent the second largest group of mammals (comprising % of all mammalian species), it is not entirely surprising that there are many bat viruses. however, some of our recent indirect evidence suggests that bats may be atypical hosts of at least some viruses. firstly, the genetic diversity and prevalence of infection of some rna viruses in bats is unusually high. we previously reported the detection of genetically highly diverse astroviruses and coronaviruses in bat fecal samples, with the prevalence of infection of these novel bat viruses in the range of - % [ , ] . however, similar surveillance studies for astrovirus and coronavirus in rodents sampled at the same geographic location indicated that none of the samples (n = ) were positive for coronavirus, whereas only . % of the tested brown rat (rattus norvegicus) samples (n = ) were positive for astroviruses [ ] . at least at this location, bats appear to harbor many more coronaviruses and astroviruses than rodents. secondly, phylogenetic analysis of viral sequences has revealed that a large number of coronaviruses recognized in other mammalian species share a common ancestor with various other bat coronaviruses ( figure ). these findings suggest that bats are likely to be the natural reservoir from which all presently known mammalian coronavirus lineages have evolved [ ] . the high prevalence of viral infection in bats, together with some of the unusual characteristics of bats discussed above, may have facilitated the transmission of bat viruses to other mammals. as surveillance data for viruses in wildlife are currently scarce, it may be premature to conclude that bats host a greater diversity of viruses than other animals. for example, more than hantaviruses have been identified in rodents -the largest group of mammals on earth ( % of all mammalian species) -and each hantavirus appears to have co-evolved with a specific rodent [ , ] . rodents are also considered to be the natural reservoir of arenaviruses with which they appear to have co-evolved [ ] and waterfowls are known to be the natural reservoir of influenza viruses [ ] . it is possible that bats, rodents, birds and other wildlife may be ancient reservoirs of different sets of virus taxa. further systematic surveillance for viruses in different wildlife populations using metagenomics or other molecular approaches is required to determine if the large number of viruses identified in bats is just simply numbers game. nevertheless, the prevalence of infection of certain bat virus families appears to be much higher than has been reported for the viral families co-evolved with rodent and avian species, suggesting that bats may have some intrinsic properties which make them more suited as a reservoir host. the five great mass extinctions that have punctuated the history of life on earth have played a major role in shaping the modern biosphere [ ] and it is reasonable to assume that mass extinctions will also have impacted profoundly on the evolutionary history of viruses. the most recent mass extinction, the k-t extinction, occurred million years ago. it followed the earth impact of the large bolide that created the - -km-wide chicxulub crater in northern yucatan, mexico [ , ] and resulted in - % reduction in marine diversity at the species level, % at the genus level, and the loss of % of all species worldwide [ , ] . the k-t extinction will also have impacted on viral diversity. indeed, as the survival of virus populations is inextricably linked to the survival of their host species, the rate of virus extinction during precipitous mass extinctions is likely to have been far greater than that of their hosts. virus extinction will have occurred not only as a consequence of host extinction but also through decreases in host population size and host isolation to a level that could not sustain ongoing virus transmission (table ) . even temporary host species decline or isolation, followed by recovery and survival, will have had potential for virus extinction. survival will have favored those viruses that could persist either in the environment or in the host, those that caused no disease or mortalities, those that were transmitted vertically, those with a broad host range, and those for which the host survived with little impact on population size. surviving host species that were largely unaffected by such a devastating mass extinction event are likely therefore to have been important sources of extant viral biodiversity. because of the exceptional paucity of the fossil record, the evolutionary history of bats is not as well documented as many other vertebrate lineages. however, as discussed above, bats are known to have origins in the late cretaceous period and appear to have diversified rapidly during the period immediately after the k-t extinction [ , , ] . it has been argued that the short intense heat pulse caused by the ballistic atmospheric re-entry of ejecta following the bolide impact created a catastrophe that set the stage for later evolutionary events [ ] . indeed, ancestral bats, rodents, insectivores and some birds are likely to have had the characteristics of animals mass extinctions, biodiversity and mitochondrial function: wang, walker and poon table effects of the k-t bolide impact on host populations and likely consequences on the contemporary virosphere. characteristics required for survival of the nuclear winter and food chain collapse that is predicted to have followed the initial impact [ ] . bats are now second only to rodents as the most ecologically and morphologically diverse mammalian clades, adapting to almost every terrestrial environment and accounting for over % of extant mammalian diversity [ ] . it follows that bats may also be one of the most important sources of extant mammalian virus diversity and supports the view that bat viruses may have ancient origins and a long history of co-evolution with their hosts. as described above, bats do appear to host a strikingly wide range of viruses and are likely the natural reservoir from which all presently known mammalian coronavirus lineages have evolved [ ] . it has also been suggested that the ubiquity, wide genetic diversity and deeply rooted phylogeny of bat lyssaviruses and paramyxoviruses indicate that bats may be their natural ancestral hosts [ , ] and bats, rodents and shrew have been found to contain integrated filovirus-like genome elements that suggest a very ancient relationship [ ] . although there may not be a direct link between host diversity and virus diversity, the long evolutionary history and the ecological diversity of bats will also have presented a myriad of opportunities for cross-species transmission of viruses to and from many other host species, further enhancing their role as amplifiers of viral biodiversity. the discovery of endogenous viral elements (eves) integrated into animal genomes appears to provide the long-sought opportunity to trace the deep evolution of viruses and the role bats may have played in shaping the modern virosphere [ ] . as discussed above, persistence in the absence of pathology or disease appears to be a common characteristic of bat viruses in their natural host population and this is also indicative of a highly evolved relationship [ , , , ] . the ecological balance that maintains infection and transmission in the absence of disease favors both pathogen and host and it can be argued that each may have contributed to its evolution [ ]. the host aims to detect and contain or eliminate the pathogen through an effective immune response to avoid disease or mortality. the virus needs only to maintain replication and transmission beyond the extinction threshold (ro > ) and the long-term survival of the virus may be improved if this can be achieved in the absence of disease or mortality [ ] . however, the high replication rate, mutation frequency and potential for recombination of viruses, particularly rna viruses, provide a potential for continual adaptation and refinement that far exceeds that of their hosts [ ] . it could be argued, therefore, that the most significant characteristic of viral infections in bats may not be the effectiveness of a highly evolved host immune response, but rather the absence of pathology as the result of an ancient and highly evolved viral survival strategy. for many rna viruses such as those commonly infecting bats, accessory proteins and evolved secondary functions of other viral proteins play a key role in infection by blocking host innate immune defences, modulating cellular signaling pathways and re-directing normal cellular functions [ ] [ ] [ ] . the refinement of these functions during a long evolutionary history in bats may well have defined a successful strategy for long-term survival, even through the periods of catastrophic environmental disruption and diminished biodiversity. conversely, the severe pathology and disease that often occurs as a result of spill-over of bat viruses into other vertebrate hosts may result not from an inherently less effective immune response but from the disturbance of this finely tuned interaction of viral proteins with their targets in host cells. it can also be argued that there are several ways in which the harboring of well-adapted viruses might also bring a biological advantage to bats. one possibility is through symbiotic enhancement of innate immunity. although innate immunity has long been considered a broad, nonspecific and nonanamnestic first line of host defence, recent studies have demonstrated that persistent infection with one pathogen may prime host innate immunity to provide cross-protection from others. this has been best illustrated by a study in mice demonstrating that herpesvirus latency confers protection from bacterial in-mass extinctions, biodiversity and mitochondrial function: wang, walker and poon table favorable characteristics for survival and proliferation following the k-t mass extinction of bats and other potential sources of extant viral biodiversity. survival fection [ ] . in a paper by roossinck, examples of 'good viruses' and virus-host symbiosis have also been reviewed for viruses infecting human, wasps, plants, fungi, aphids and bacteria [ ] . highly adapted viruses persistently infecting bat populations might also serve to protect bats at the species or population level from predators (e.g., tree roosting animals such as raccoons and opossums, owls and hawks, and primates) in a sense acting as defensive 'biological weapons'. the best defensive weapons are those that do no harm to the host species and are released only when there is an imminent threat of danger and the emerging bat viruses (e.g., henipaviruses and filoviruses) satisfy these requirements. henipaviruses are believed to persist in bat populations at a very low viral load and are totally harmless to their natural host. however, under stress, the viral load increases, facilitating transmission to other animals [ , ] . they have a very broad range of susceptible hosts and are highly lethal in many different vertebrate species [ ] . such a mechanism might not be able to protect every individual animal in a population, but it would be an effective way to preserve the species. in principle, such a symbiotic relationship with viruses would benefit any animal species and there is evidence that such relationships do exist in very different hosts including humans, mice to fungi and bacteria [ ] . it is perhaps the long period of co-evolution and some unique selective pressures that have driven its emergence and dominance in bats. bats have a relatively low reproductive rate (usually one birth with one pup per year) compared to other animals such as rodents and, as discussed above, bats tend to live in very large and dense populations. these biological and behavioral characteristics may demand far more robust mechanisms to fight infection and predation in order to avoid extinction. flight capability, longevity and innate immunity -are they linked? as discussed above, some of the 'unique' biological characteristics of bats are believed to contribute to the observation that they appear to harbor a large number of viruses without clinical signs of disease. while the scientific data are not sufficient to make any conclusive link, it is tempting to speculate on the interplay for some of these factors. in table , three key aspects of the biology of bats are analyzed in the context of their impact on cellular metabolism and infectious agents. flight ability is the most distinguishing feature of bats amongst mammals. flight consumes a large amount of energy, demanding a much higher rate of metabolism. in general, it is believed that a high metabolic rate, such as that in bats, is likely to generate more metabolic byproducts, which, in turn, will increase the rate of oxidative damage to mitochondrial dna and other cellular structures [ ] . according to the 'rate of living' theories, animals with a high metabolic rate are likely to be short-lived [ , ] . although the combination of small body size, high metabolic rate and long lifespan in bats does not seem to be compatible with this view, recent studies on mitochondrial dna and cellular processes have indicated that multiple mechanisms exist in bats (and other long lifespan animals such as birds) to allow them to be more efficient in resisting oxidative damages than short lifespan animals [ ] . oxidative damage to dna is also an important mechanism of tumorigenesis [ ] . it is therefore interesting that unpublished anecdotal observations suggest that bats have a lower rate of tumorigenesis than most other animals. an extensive literature search revealed only a few recent papers describing tumors in egyptian fruit bats [ ] [ ] [ ] . in one case, a sarcomatoid carcinoma was diagnosed in the lung of a -year-old male captive bat, and in the other case a gastrointestinal leiomyosarcoma was found in a -yearold female bat. during our own study to establish bat cell lines, a wide international collaborative effort examining bats from australia, asia and africa failed to identify any tumors from a large number of individual bats representing more than ten different bat species [ ] (g. crameri, l.-f. wang, unpublished observations). although the jury is still out, it is not impossible that efficient mechanisms for countering oxidative damage in bats result in a lower rate of tumorigenesis. on the other hand, it is also possible that the low reporting rate of bat tumors results from a lack of appropriate detection/diagnostic methods for bat tumors or general interest in this area of research. mitochondria are key organelles in controlling cellular metabolism. for bats, the efficient function of mitochondria emerging viruses table potential association of unique bat biological features with a symbiotic relationship with viruses. unique biological feature impact on metabolism impact on infectious agents true ability to fly requiring more energy efficient metabolism greater chance of inter-species and long distance transmission rapid change of body temperature highly efficient sensing and regulation of temperature effect on immune system favoring persistence long lifespan relative to body size more efficient mechanism to prevent oxidative damage to dna is likely to be essential for key biological characteristics such as flight, body temperature changes and lifespan, all of which could impact on the ecology of viral infection (table ) . until very recently, it was not recognized that mitochondria also act as a center of signaling pathways for apoptosis, inflammation and innate immune responses [ , , ] . this is a very new and rapidly evolving field of research but it is clear that mitochondria are involved in signaling for antiviral and antibacterial immunity [ ] . all published studies to date have been conducted in human or mouse cell lines so it will be extremely interesting and important to conduct parallel studies in bat cells to determine whether mitochondria have similar functions in controlling innate immune responses in bats. in summary, we speculate that the key unique biological features of bats, that is, ability to fly, high metabolic rate and longevity, are functionally interconnected and mitochondria are the key cellular organelles that link all of these processes. these features, in turn, all have an impact on the bat's ability to control tumors and infection. this fundamental and common innate ability of bats may help explain their seemingly super anti-ageing, antitumor and anti-infection characteristics. multiple hypotheses are presented in this review in an attempt to address the question as to whether bats are special as reservoir hosts of viruses. while we are not able to provide a definitive answer to the question, we hope that the range of new ideas and angles presented here will stimulate those who work in the field to explore further in the future. it is possible that all of the aspects discussed here, although some of them seem to be mutually exclusive, may play a part in the overall picture of high-rate detection of viruses and infection with no diseases in bats. if bat's innate ability to counter biological imbalance proves to be different from or more robust than other mammals in whatever way or shape, it will provide a tremendous opportunity for us to 'learn from bats' and apply some of these principles to human and animal health, either via therapeutic intervention in humans or transgenic modification in livestock animals. however, one must recognize that despite the great interest in bat viruses in recent years, bat biology research is in its infancy compared with existing knowledge of infection in humans and other animals such as rodents. there is a total lack of research tools and reagents to address any of the hypotheses in depth. thus, there is an urgent need to advance the basic study of bat biology and bat immunology to help remove the road blocks. taylor dj, leach rw, bruenn j: filoviruses are ancient and integrated into mammalian genomes. bmc evol biol , : . this is the first report of endogenization in the mammalian genome of nonretroviral rna viruses with extranuclear replication. the endogenous viral elements were most commonly detected in bats, rodents and insectivores. phylogenetic analysis suggested an ancient association between filoviruses and mammals that was dated to tens of millions of years ago. olival kj, epstein jh, wang l-f, field he, daszak p: are bats unique virus reservoirs? in conservation medicine, edn . edited by aquirre aa, ostfeld rs, daszak p. oxford university press (in press). a recent review on the same topic as this review, but focusing on different aspects. it is worth to read this book chapter in conjunction with the current review for a more complete appreciation of the subject. bats and viruses: a brief review sur une grande epizootie de rage swanepoel r: fruit bats as reservoirs of ebola virus a morbillivirus that caused fatal disease in horses and humans nipah virus: a recently emergent deadly paramyxovirus bats are natural reservoirs of sars-like coronaviruses severe acute respiratory syndrome coronavirus-like virus in chinese horseshoe bats henipaviruses: emerging paramyxoviruses associated with fruit bats henipavirus vaccine development. j bioterrorism biodefense ebola outbreak killed gorillas the ecology of ebola virus bats, clocks, and rocks: diversification patterns in chiroptera order chiroptera early eocene bat from wyoming linking the wasatchian/bridgerian boundary to the cenzoic global climate optimum: new magnetostratiographic and isotopic results from south pass a highresolution genetic signature of demographic and spatial expansion in epizootic rabies virus placental mammal diversification and the cretaceous-tertiary boundary a molecular phylogeny for bats illuminates biogeography and the fossil record host and viral ecology determine bat rabies seasonality and maintenance an example of using mathematical modeling to identify factors that are important for viral infection dynamics in bat populations novel astroviruses in insectivorous bats identification of a novel coronavirus in bats detection of novel astroviruses in urban brown rats and previously known astroviruses in humans the most recent paper out of a series studies on astroviruses conducted by the hong kong group, which demonstrated that the genetic diversity of astroviruses in bats is greater than those in other mammals evolutionary insights into the ecology of coronaviruses emergence and persistence of hantaviruses virus evolution and genetic diversity of hantaviruses and their rodent hosts evolution of the old world arenaviridae and their rodent hosts: generalised host-transfer or association by descent? influenza: emergence and control mass extinctions in the marine fossil record new links between the chicxulub impact structure and the cretaceous/tertiary boundary extraterrestrial cause for the cretaceous-tertiary extinction. experimental results and theoretical interpretation extinctions in the fossil record selectivity of end-cretaceous marine bivalve extinctions the delayed rise of present-day mammals a phylogenetic supertree of the bats (mammalia: chiroptera) survival in the first hours of the cenozoic evolutionary biology -a first for bats primitive early eocene bat from wyoming and the evolution of flight and echolocation a bony connection signals laryngeal echolocation in bats energy, volatile production, and climatic effects of the chicxulub cretaceous/ tertiary impact reassessing conflicting evolutionary histories of the paramyxoviridae and the origins of respiroviruses with bayesian multigene phylogenies genomic diversity and evolution of the lyssaviruses endogenous viral elements in animal genomes this paper reports the use of a systematic screening in-silico to detect the common occurrence of endogenous elements derived from a diverse array of dna and rna viruses in animal genomes. analysis of the sequences of the endogenous viral elements (eves) with respect to extant viruses indicated ancient origins infectious disease modeling and the dynamics of transmission the evolution and emergence of rna viruses mechanisms of severe acute respiratory syndrome pathogenesis and innate immunomodulation understanding the accessory viral proteins unique to the severe acute respiratory syndrome (sars) coronavirus inhibition of interferon induction and signaling by paramyxoviruses virgin hwt: herpesvirus latency confers symbiotic protection from bacterial infection the good viruses: viral mutualistic symbioses an updated review on virus-host symbiosis. it is an excellent paper to read for those wishing to learn a bit more about the importance and progress in this area of research anthropogenic deforestation, el nino and the emergence of nipah virus in malaysia nipah virus outbreak in malaysia hendra and nipah viruses: different and dangerous oxidative damage to dna: relation to species metabolic rate and life span bats and birds. exceptional longevity despite high metabolic rates an excellent review for anyone who is interested in the subjects of aging, longevity and flying ability of animals in the rate of living viral oncogene-induced dna damage response is activated in kaposi sarcoma tumorigenesis sarcomatoid carcinoma in the lung of an egyptian fruit bat (rousettus aegyptiacus) gastrointestinal leiomyosarcoma in an egyptian fruit bat (rousettus aegyptiacus) microchip-associated leiomyosarcoma in an egyptian fruit bat (rousettus aegyptiacus) establishment, immortalisation and characterisation of pteropid bat cell lines emerging role of damageassociated molecular patterns derived from mitochondria in inflammation this paper describes the establishment of bat primary and immortalized cell lines which are becoming increasingly important for isolation of bat viruses and for basic study on virus-bat interaction recent advances in apoptosis, mitochondria and drug resistance in cancer cells mitochondria in innate immune responses mass survival of birds across the cretaceous-tertiary boundary: molecular evidence the role of mitochondria in innate immunity is a relative new topic in immunology and this updated review provides an excellent starting point to review the recent discoveries and future research directions bat mating systems impact winter and the cretaceous-tertiary extinctions -results of a chicxulub asteroid impact model a theoretical exercise in the modeling of ground-level ozone resulting from the k-t asteroid impact: its possible link with the extinction selectivity of terrestrial vertebrates evidence for echolocation in the oldest known bats impact of the terminal cretaceous event on plant-insect associations we thank e.c. holmes for useful discussions on the evolution of bat viruses. key: cord- -xwuz ma authors: hernandez-ortega, javier; daza, roberto; morales, aythami; fierrez, julian; tolosana, ruben title: heart rate estimation from face videos for student assessment: experiments on edbb date: - - journal: nan doi: nan sha: doc_id: cord_uid: xwuz ma in this study we estimate the heart rate from face videos for student assessment. this information could be very valuable to track their status along time and also to estimate other data such as their attention level or the presence of stress that may be caused by cheating attempts. the recent edbbplat, a platform for student behavior modelling in remote education, is considered in this study . this platform permits to capture several signals from a set of sensors that capture biometric and behavioral data: rgb and near infrared cameras, microphone, eeg band, mouse, smartwatch, and keyboard, among others. in the experimental framework of this study, we focus on the rgb and near-infrared video sequences for performing heart rate estimation applying remote photoplethysmography techniques. the experiments include behavioral and physiological data from different students completing a collection of tasks related to e-learning. our proposed face heart rate estimation approach is compared with the heart rate provided by the smartwatch, achieving very promising results for its future deployment in e-learning applications. nowadays e-learning is experiencing a period of high growth thanks to the flexibility it provides to students who do not have the possibility to access to traditional education, like users with an employ, geographical limitations, or any other special conditions. trying to reach that increasing market of potential students, most of higher education institutions like stanford, harvard, oxford, and the mit have started to offer new options of virtual education [ ] . moreover, episodes such as the covid- outbreak in and the social distancing imposed, have demonstrated the necessity to develop new technologies to improve e-learning platforms. even though e-learning presents many advantages, it also has some drawbacks, being one of the more relevant the difficulty to demonstrate if an online evaluation is really being carried out by a specific student. without this verification step, it is hard to know if a student has acquired the knowledge associated to a certain course, or if he is incurring in some type of fraud/cheating on the evaluation, e.g. asking another person to complete his/her exam. biometric technologies seem to be a perfect choice to enhance virtual education environments. these technologies allow to identify a person by their physiological and behavioral characteristics, rather than traditional methods such as a https://github.com/bidalab/edbb password or an id card that could be lost, forgotten, or used by another person to perform student impersonation [ ] . the interaction between the students and the computer or the device in which they are accessing to the educational contents can be used to acquire other information about their state, e.g. their heart rate, their level of attention, and how much stressed they are [ ] . these type of factors, i.e. stress, emotional state, motivation, focus, and attention, can affect the effectiveness of the learning process [ ] , [ ] . a student who is affected by any external agent or emotion will not take as much benefit of the lessons as another that is totally focused. traditional education theory has been centered in how to explain the contents to the students in the best way possible, but usually without considering these context and human factors. for online education, these elements are specially crucial. the main contributions of this study are: • a brief survey of state-of-the-art biometric and behavioral technologies based on human-computer interaction (hci) with potential application to student monitoring. • the acquisition of a dataset consisting of biometrics and behavioral data using the student monitoring platform for e-learning edbbplat [ ] . this database (edbbdb) is publicly available for research purposes (see footnote on this page). • an experimental evaluation of heart rate estimation in the edbb framework, and the development of a baseline algorithm for heart rate estimation based on remote photoplethysmography. • application of the developed baseline algorithm to two different scenarios in a simulated e-learning environment: one of them consists in estimating the mean heart rate of the students over a whole session and the other consists in making a continuous heart rate estimation during a session (useful for detecting heart rate alterations). the rest of this paper is organized as follows. section ii introduces behavioral biometrics and their application to e-learning scenarios. section iii provides details about the structure of edbbplat. section iv explains the different challenges related to student monitoring proposed in the edbb framework, being one of them heart rate estimation. section v shows the experimental protocol and the results achieved for the heart rate estimation sub-challenges. finally, conclusions are drawn in section vi. historically, the first approaches for monitoring student evaluations in remote learning have consisted in installing a special software in the student's computer. this software is intended to be connected to an institutional server in which a learning management system (lms) controls that users do not perform any forbidden action during their evaluations, i.e. executing certain applications such as the web browser, making screenshots, running certain commands, etc. the usage of online supervisors, i.e. people that manually supervise each session by webcam, allows to monitor students in real time in a similar way as in a classroom. however, this method is not scalable to a large number of students. the possibilities of biometric-based technologies for monitoring online evaluations have been recently showed in real world applications like the coursera e-learning platform. in this case, the programmers used keystroke methods [ ] , [ ] for verifying the identity of the students enrolled in a course. behavioral biometrics refers to those biometric traits that describe the way that users perform different actions [ ] . behavioral biometrics traits can be extracted from human-computer interaction, in which a person interacts with some devices, such as computers and smartphones, in a manner that can be highly different among them [ ] - [ ] . a machine learning algorithm can learn patterns from hci data. these patterns will be affected by several factors like the acquisition sensors, the tasks that are being captured, or the human condition and behavior. modelling these data (that usually comes from heterogeneous sources) is useful for a multitude of applications such as elearning, security, entertainment, and health. behavioral biometrics is composed by different traits like touchpad interaction [ ] , keystroking [ ] , mouse dynamics [ ] , [ ] , handwriting patterns [ ] , and stylometry. relevant works in this field of research demonstrate that the information coming from hci can be used not only for user authentication, but also for characterizing other human features like [ ] : neuromotor and cognitive abilities [ ] , physiological signals such as human pulse [ ] , and human behaviors/routines. we employed the platform from [ ] , called edbbplat. it has been designed for capturing data for automatic detection of anomalous behaviors in virtual evaluation environments. table i shows the sensors and the types of data captured by the platform. the data is acquired through a set of activities for the students to complete. the acquisition setup consists of (see fig. left): • video: rgb cameras ( frontal, side, and zenital), near infrared cameras (intel real-sense model d i), and depth images. • pulse and motion sensors: we employed a huawei watch smartwatch that captures pulse and motion signals including accelerometer, magnetometer, and gyroscope. • a personal computer with microsoft windows , a mouse, a keyboard, a microphone, and a screen. the computer is used by the students to complete the tasks, while the screen data, the mouse and keyboard dynamics, the audio, and other pc metadata are being acquired in the background. the activities that conform the platform consist of different tasks categorized in main groups: • enrollment form: meant for obtaining personal data of the students, e.g. name and surname, e-mail address, id number, and nationality. • writing questions: since this type of questions are more complex, they can be used to measure the students' cognitive abilities under different situations such as: solving logical problems, describing images, crosswords, finding differences, etc. additionally, some activities have been designed to induce different emotional states to the participants, e.g. stress or nervousness. • multiple choice questions: these are questions largely used in online assessment platforms and are included to detect the students' attention and focus levels. an example of the employed sensors and of the information that is acquired while a student is completing a task can be seen in fig. . the work in [ ] proposed different challenges that are relevant to student monitoring: • challenge -attention estimation: the estimation of the intensity of mental focus or attention of the students. • challenge -anomalous behavior detection: detection of non-allowed activities performed by the students. • challenge -performance prediction: prediction of accuracy and time necessary for the completion of the tasks. fig. . example of the information acquired for heart rate estimation using remote photoplethysmography. the acquisition setup can be seen in the left diagram. the sensors of the realsense camera used in this case are the rgb and the left and right near infrared channels (top-right images). we show two different groundtruth heart rates captured with the huawei watch smartwatch (bottom-right plots). in these plots, the points in which the users were asked to perform physical activity are highlighted. and, finally, the fifth challenge, which is the main focus of the present paper: • challenge -pulse estimation: changes in the human pulse have showed to be related to altered emotional states and the presence of stress. emotional states can affect perception and performance. understanding the emotional state of the student may help in different ways: ) online adaptation of the session according to the emotional state (e.g. reducing working load and the difficulty or type of the contents); ) improved performance analysis including emotional features. the objective of this challenge consists in estimating the groundtruth human pulse (obtained from the smartwatch) by using the front camera. alternatively, the nir cameras present in the acquisition setup can be used to analyse the potential of this type of sensors. in this study we propose an accurate estimation of the heart rate through remote photoplethysmography (rppg) techniques applied to face biometrics [ ] . the proposed benchmark is divided into the following two different sub-challenges related to the student activity monitoring: • sub-challenge . -heart rate averaged by session: knowing the mean heart rate of a student for a whole session can be useful for comparing these values across different sessions. this way we can track the student's activity along time for detecting unusual events. the average heart rate during the task, the grade obtained, and the student historic data (previous average heart rate and grades) can serve to obtain a detailed picture of the student's performance. • sub-challenge . -heart rate continuous monitoring: this challenge consists in dividing each session in shorter temporal windows and estimating the heart rate for each one of them individually. unlike the first sub-challenge, this approach can be useful for analyzing the state of the student throughout a single session and detecting anomalous behaviors within the session. additionally, this information is useful to better understand the potential difficulties faced during the tasks. plethysmography refers to techniques for measuring the changes in the volume of blood through human vessels. this information can be used to estimate parameters such as heart rate, arterial pressure, blood glucose level, or oxygen saturation levels. the variant called photoplethysmography (ppg) includes low-cost and noninvasive techniques associated with imagery and the optical properties of the human body [ ] . oxygenated blood absorbs more light at specific wavelengths than the blood with less oxygen, so measuring over time the amount of light reflected by the tissues of a person, we can estimate his pulse signal and other parameters like respiration variability [ ] . studies have proven that it is possible to measure the changes in the amount of oxygenated blood through facial video sequences [ ] . these techniques are called remote photoplethysmography and their operating principle consists in looking for slight changes in the skin color at video recordings using signal processing methods [ ] . remote ppg methods can take advantage of cameras that contain both rgb and near result of the heart rate estimation (right). the highest peak in the acquired heart rate corresponds with a moment in which the student was requested to perform a seconds period of physical activity to get him into an altered state. the mean heart rate for the whole session (sub-challenge . ) and the values of the heart rate for second windows (subchallenge . ) are also shown. infrared sensors. the nir spectrum band information is highly invariant to light conditions, providing robustness against this external source of variability at a low cost. the nir band can also help to derive depth information that could improve the location accuracy of the regions of interest (roi) at face tracking. our approach is based in the one presented in [ ] and consists in four main stages: i) we first locate and track different regions of interest in the student's faces, i.e., the forehead and the right and left cheeks (see figure left); ii) we track the regions during the video and we extract their raw rppg signals; iii) we postprocess the raw rppg signals from the regions using a moving window to isolate the component associated to the pulse by minimizing the other components in the video sequences; and iv) we estimate the value of the heart rate for each temporal window by analyzing the frequency components of the postprocessed rppg signal and we concatenate all these values for obtaining the heart rate estimation for all the video sequence (see fig. we have acquired different students while completing the tasks described in section iii-b. the duration of each video recording is variable, going from to minutes. one session has been recorded for each student. the video sequences have been captured at frames per second with the intel realsense camera (we have used both the rgb and the nir channels), with a resolution of × pixels. the groundtruth for the heart rate has been acquired with the huawei watch smartwatch at a sampling frequency of hz. an example of the images captured with the realsense camera and the smartwatch can be seen in fig. right. during the acquisition, each student had to perform physical activity in a different moment of the evaluation in order to put him into an altered state with a higher heart rate. with the physical activity we intended to simulate possible situations in which the pulse of the student may vary due to events such as high stress or cheating attempts. we are aware that physiological changes are highly related with the nature of the stimulus. changes in the pulse due to physical activity may show different physiological responses that those caused by stress level for example. however, the resulting changes in the heart rate should be similar. we decided to use the rgb and the nir channels in order to compare the results obtained with each type of images. however, in most acquisition setups, the only available sensor will probably be a rgb camera, so we have centered our analysis in the results obtained with that frequency band. the metric used to report the accuracy in the heart rate estimation challenge is the mean average error (mae) expressed in beats per minute (bpm). mae refers to the mean difference in absolute value between the estimated heart rate and the groundtruth. this metric can give us an idea of the average accuracy we can expect of our heart rate estimation method, thus giving us orientation of its possible applications. there are slight differences in the protocol we followed for each one of the two sub-challenges. the first step is common to both challenges: we divided the video sequences in temporal windows of a fixed length and we computed a value of the estimated heart rate for each one of these windows. regarding the groundtruth heart rate, we computed the mean value of the samples acquired with the smartwatch from each temporal window. ) sub-challenge . -heart rate averaged by session: for computing the mean heart rate of a whole session we calculated the average of the heart rate estimations of all its temporal windows. then we used the absolute difference between the estimated mean heart rate and the groundtruth as our error metric in beats per minute (bpm). we have selected values for the window length going from to seconds with an increment of seconds. in this case we took the estimated heart rate and the groundtruth heart rate for each single window and we calculated the absolute difference between them. after that we averaged the error of all the windows inside each video sequence. the results of each session were then combined to produce a single performance measure for the whole dataset, i.e. the mean average error (mae) expressed in bpm. in this case we explored values for the window length going from seconds to seconds with a step of seconds. in this sub-challenge we have calculated the mae values for the estimation of the heart rate for complete sessions. the rppg algorithm used in this work employs information from the three color channels available in rgb videos. however, in nir videos only one channel is available, so we replicated its information into three different channels to imitate a rgb video. in table ii we can observe a clear trend of the heart rate estimations, where the nir videos obtain a higher accuracy when using short video windows, while the rgb-based estimation is the most accurate when using a longer window duration. the accuracy obtained is high for both types of videos, being slightly higher for the nir band when using short windows, and better for the rgb color channel when using a wider temporal window. we think that this may be caused by the fact that the nir band is more robust to external illumination changes that affect severely to the rppg heart rate estimation. however, for longer window sequences, having more information available (three channels instead of one) makes possible to obtain better rppg signals. this sub-challenge may be applicable for monitoring the state of the students between sessions, i.e. knowing in which fig. . temporal evolution of the heart rate in a scenario in which the student has been induced to an altered state by means of physical activity at the beginning of the session. the four plots correspond to the same video sequence but with different temporal window lengths. the figure shows the changes in the accuracy when changing the length of the temporal window. classes or evaluations the mean heart rate is higher or lower. these alterations may be caused by user impersonation, lack of interest, or a high level of stress. ) sub-challenge . -heart rate continuous monitoring: table iii shows the performance results for heart rate estimation obtained for different values of the temporal window, going from seconds to seconds, and also for both the rgb and the nir bands. it can be seen that the mae decreases when increasing the temporal window length because the algorithm has more information for extracting the frequency components correspondent to the heart rate. however, when the window duration reaches a limit (close to seconds in both cases) the mae does not further improve due to the variations of the heart rate inside a too long window. other drawback related to the use of a longer temporal window is the lower temporal resolution of the predictions. if the heart rate changes quickly, a long temporal window will not be able of capturing that behavior. similarly to the case of the subchallenge . , in this case the accuracy is slightly higher for the nir band when using short windows and better for the rgb color channel when using a wider temporal window. fig. shows the temporal evolution of the heart rate estimation in a scenario in which the students performed physical activity at some points of the evaluation in order to get their heart rate artificially high. the target is checking if the heart rate estimation algorithm is capable of detecting these changes in the heart rate. by inducing alterations we want to simulate a situation in which a student performs any forbidden or inappropriate action, e.g. cheating, that may lead to an altered heart rate. the four plots in the figure correspond to the same video sequence but with a different temporal window length. the figure shows how the estimation algorithm manages to capture the main behavior of the heart rate during the induced alterations. it also reflects the change in the accuracy for the heart rate estimation for the same video sequence when changing the value of the temporal window. as has been said previously when commenting the results of table iii , a higher value for the temporal window makes the mae to decrease. this is shown in fig. with the plot of the averaged groundtruth and estimated heart rates, that become closer when increasing the temporal window length. however, it can also be seen that even though using smaller windows decreases the general accuracy of the heart rate estimation, it also allows to reflect better the quick changes in the heart rate due to the altered states induced in these experiments. these quick changes in the heart rate can only be captured when using lower values for the temporal window. this way, the decision of what window length must be used depends of the desired application. in this paper, we have: i) discussed the application of behavioral biometrics for remote education, ii) employed edbbplat [ ] , a platform of biometrics and behavior for student assessment during virtual education, iii) captured data from sensors that are usually present in remote education (rgb cameras), and also from more advanced sensors like nir cameras and a smartwatch, and iv) used the acquired nir and rgb video recordings for estimating the heart rate of the students using rppg while they are completing a series of virtual evaluation tasks. the type of information acquired in this work can be used for detecting unusual events during an evaluation task in remote education. some examples of events that can be detected are: cheating attempts, a stress level out of the ordinary values, drops in the level of attention of the students, or changes in their heart rate. for future work, we expect to add different types of stimuli that lead to altered states. correlating those altered states with the information from the other basic and advanced sensors of the platform (eeg band, other cameras, test results, etc.) may be helpful for detecting inappropriate behaviors and other factors such as the stress level, the focus level, or even for trying to predict some variables like the student's performance. students' perceptions of teaching and social presence: a comparative analysis of face-to-face and online learning environments biometrics systems under spoofing attack: an evaluation methodology and lessons learned photoplethysmography and its application in clinical physiological measurement academic emotions in students' self-regulated learning and achievement: a program of qualitative and quantitative research emotions in classrooms: the need to understand how emotions affect learning and education biometrics and behavior for assessing remote education keystroke biometrics ongoing competition typenet: scaling up keystroke biometrics years of biometric research: accomplishments, challenges, and opportunities understanding and changing behavior smartphone sensors for modeling humancomputer interaction: general outlook and research datasets for user authentication benchmarking touchscreen biometrics for mobile authentication what can a mouse cursor tell us more?: correlation of eye/mouse movements on web browsing becaptcha-mouse: synthetic mouse trajectories and improved bot detection benchmarking desktop and mobile handwriting across cots devices: the e-biosign biometric database active detection of age groups based on touch interaction a comparative evaluation of heart rate estimation methods using face videos photoplethysmography: beyond the calculation of arterial oxygen saturation and heart rate advancements in noncontact, multiparameter physiological measurements using a webcam time analysis of pulse-based face anti-spoofing in visible and nir key: cord- -wuuhlowd authors: valkonen, tarmo title: the finnish pension system and its future challenges date: - - journal: inter econ doi: . /s - - - sha: doc_id: cord_uid: wuuhlowd a specific feature in the finnish pension system is rule-based preparation for mortality change. the earned pension capital is adjusted to life expectancy and the lowest age limit of the flexible retirement age will be adapted so that the ratio of expected years in employment and retirement is fixed after year . forum return on funds is low, and the amount of excess is saved to support the funding. the pension scheme is run by private pension companies and other pension institutes, which are individually liable for the pre-funded part of the pensions, but mutually responsible for fi nancing the payas-you-go part. public sector schemes have buffer funds that aim to smooth contribution rates. as an outcome, about a third of the accrued earnings-related pension rights are pre-funded. the main challenge of the pension system is population ageing, which is escalating in finland due to the recent large fall in fertility. if the number of children remains low and net migration does not increase markedly, there will be a growing need to increase contribution rates. moreover, the life expectancy adjustment of pensions lowers replacement rates if mortality rates fall as expected. it will be compensated partly by longer working careers, but full compensation would require a faster-than-projected increase in employment rates. other risks that may infl uence the sustainability of the pension system include lower growth in employment and wages due to technological development as well as lower pension fund yields than expected. this review fi rst provides a brief outlook on the various development stages of the finnish pension system that are still visible in its basic structure and the logic of the current version. the subsequent section illustrates with some key indicators how the current system has succeeded in reaching its goals and shows its risk-sharing properties. this is followed by a discussion of how the pension system is prepared to cope with future challenges that are common to pension schemes across industrialised countries. the concluding section suggests changes that could make the finnish system even more resilient. the history of finnish old age pensions dates to pensions of the civil servants in th century, but a fi rst scheme with substantial coverage was established in , when the national pension system was introduced. this earnings-related scheme was based on fully funded individual accounts. the negative experiences of war-time infl ation and political resistance led to the pension reform that included abandonment of pre-funding, equalisation of pensions, introduction of income-and wealth-tested the finnish pension system has succeeded in gaining high social, and reasonable fi nancial sustainability. the balance between reaching the ambitious redistribution goals and minimising labour supply distortions is achieved with tax-fi nanced, income tested basic pensions, income-tested basic pensions and a strong link between wage income and accrued pensions for middle-and high-income workers in the earnings-related schemes. these well-governed fi rst-pillar schemes have high coverage and similar benefi t rules. second pillar occupational pensions are rare in finland. one of the secrets of its success has been the capacity to make extensive reforms when required. by law, the earnings-related pension scheme follows the defi ned benefi t rule, where contribution rates adjust to shocks that weaken the contribution base or increase expenditures. in practice, however, an outlook of a strongly increasing contribution rate has often triggered a reform process. both the negotiations and the full implementation of the reforms have taken time, but the outcomes have been largely accepted. a specifi c feature in the finnish pension system is rulebased preparation for mortality change. the earned pension capital is adjusted to life expectancy and the lowest age limit of the fl exible retirement age will be adapted so that the ratio of expected years in employment and retirement is fi xed after year . postponed withdrawal of pensions is rewarded in an actuarially fair way. this set of rules generates strong incentives to extend working life when life expectancy increases. hence, the rules promote adequacy of pensions and fi scal sustainability. another non-standard element is the partial pre-funding of the fi rst-pillar earnings-related benefi ts. the share of contributions that is pre-funded in the dominating private sector pension scheme (tyel) is small, but the required forum creased the investments in stock and foreign markets. the public sector pension institutes started buffer-type pre-funding of the contributions in the late s. an extensive and radical pension reform took place in . the reformed rules form the backbone of the current pension system. key elements were the harmonisation of the benefi t rules of different earnings-related schemes, a tighter link between earned income and accruals, introduction of fl exible old age retirement, gradual abolishment of several early retirement schemes and the introduction of a link between life expectancy of the retiring cohort and the pensions. pension accrual starts from an earlier age and smaller amounts of wages are counted. a pensionable wage is determined by the whole working career. pensions are fully portable allowing job and sector changes without losses in accrued amounts. the maximum replacement rate was abolished. the accrued pension rights are indexed to average wages and consumer prices with weights / during working years. for the pensions in payment, the ratio is / . some pensions accrue also during periods of unemployment, child care, sick leave and studies. the possibility to withdraw the pension was separated from the decision of retiring from work. the only remaining link was that postponement of pension withdrawal was rewarded with a higher accrual rate only when working life continued. flexible retirement allowed retirement between the ages and , but withdrawal at age caused a marked loss in the pension if the person was not unemployed long term. one of the ideas behind the fl exible retirement age was that the expected future decline in pensions due to increasing longevity could be compensated by extending voluntarily working careers. it turned out, however, that old age retirement concentrated at age and there was the risk of a continuously falling replacement rate. the observed reluctance to extend voluntarily working lives and a continued rise in projected life expectancy generated the need for a new pension reform. it was understood that the low retirement age endangered both adequacy of pensions and fi nancial sustainability of the general government. the reform, implemented in , introduced a stepwise increase in the lower age limit of the fl exible pension age until it reaches age in and establishes a link between life expectancy and the lowest retirement age in . the link is calibrated so that for each additional year of life expectancy, the lower age limit goes up by eight months. the link is also applied to basic pensions and early retirement pensions except disability pensions. the upper age limit of the fl exible retirement age will be raised from to years. supplementary allowance and tax fi nancing. in , the basic part of the pension was abolished and only the income-tested part of the national pension remained. the guarantee pension, which defi nes the minimum amount of pension income, was introduced in . disability pensions were part of the system from the beginning. the general earnings-related private sector pension scheme was introduced in . while based on law, it was an outcome of negotiations between labour market parties. since then, the social partners have had a decisive role in the preparation of pension reforms and strong representation in the governing bodies of the pension funds. different sectors prepared their own laws during the s and ended up with a different set of rules. the low retirement ages and high accrual rates of the public sector schemes particularly stuck out. the private sector schemes and the national pension scheme had a retirement age of years. during the next two decades, benefi ts were expanded. in the s, the accrual rates were raised markedly, and the initially low pensions were topped up with discretionary increases. the unemployment pension was introduced for the long-term unemployed who were at least years of age. the eligibility age for these pensions was lowered to years in the s. several new early retirement schemes were introduced in . the popularity of early retirement surprised policy planners. the deep recession in the beginning of the s and the continuous increase in life expectancy initiated a period of retrenchments. first, the liability to pay pension contributions, previously solely on employers, was partially shifted to employees. more importantly, it was agreed that the future increases in contributions are distributed on a / basis. the true incidence of the hikes in the employers' contribution rates had always been mainly on wages because they were agreed by the central labour market parties, but this reform further strengthened the responsibilities of the labour unions. also, a long process of limiting access to early retirement schemes started. the investment policies of pension funds changed radically during the s. in times of undeveloped fi nancial markets, pension wealth was an important source of liquidity and investment funding for domestic fi rms. the real rate of return on pension funds was often negative due to a high infl ation rate and the use of investment income exceeding the required return to lower contributions. the development of the fi nancial markets and the alleviation of investment regulations of the funds promoted by striving for higher returns and more diversifi cation rapidly in-forum does not capture the growth of real wages. when the gap between purchasing power of basic pensions and earnings-related pensions became large enough, political reality required discretionary increases in the level of these pensions. the importance of the income-tested basic pensions has declined strongly during recent decades because the maturing of the earnings-related pension schemes has reduced the number of eligible pensioners with suffi ciently small earnings-related pensions. pension income represents about % of all incomes of pensioners. the rest comprises mainly labour and capital income. the disposable income of pensioners is also infl uenced by strongly progressive taxation, which leaves pension income from national pensions untaxed. the poverty rate among pensioners is % (when the criterion is % of the median disposable income), which is the same as the average rate in the total population and somewhat lower than the eu average. living standards of pensioners are also supported by the extensive underpriced public health and long-term care services. the finnish centre for pensions provides long-term projections on pensions, total expenditure and contribution rates (tikanmäki et al., ) . the outlook, based on the population projection of statistics finland, shows that the ratio of average total pensions to average wages is expected to decline by around ten percentage points in years mainly because of the life expectancy adjustment of pensions. the outlook of the fi nancial sustainability of the earningsrelated pension system strongly depends on the time period studied. the passing of the baby boomer generation starts to bring down the ratio of expenditures to gdp in the s. low fertility and extending longevity turn the trend when approaching the middle of the century. the main private sector pension scheme can keep the contribution rates stable until the s, but after that there will be a strong and continuous increase. if the scheme aims to smooth development of contributions until , it should raise the contribution rate immediately by . percentage points (tikanmäki et al., ) . this means that the scheme is not fi nancially sustainable. in the public sector, the current very high costs are expected to converge in the long term towards the same level as in the private sector, which allows a minor decline in the ratio of contributions to wages. the pension reforms, together with improved education and health of the retiring cohorts have increased the employment rates of elderly persons dramatically in finland. the gain in the - age group has been more than percentage points since the pension reform, which the higher accrual rate earned from work after the lowest retirement age was replaced by a reward for postponing withdrawal of the pension. the reform also included two minor changes in early retirement schemes. the generous part-time pension scheme was replaced by the actuarially fair possibility of drawing part of the old age pension from age . the second new element is a years-of-service pension, which can be drawn from age if a stressful working career has continued for at least years and the working capacity of the individual has declined. the years-of-service pension remains unpopular because access to benefi ts is complicated and uncertain and it is smaller than the disability pension. the goal of higher employment periods near retirement has been supported by shortening the period of earnings-related unemployment benefi ts paid before reaching the lowest eligibility age for old age pensions. private sector pensions are fi nanced by contributions collected from employers and employees. contributions are deductible in income taxation, pensions are taxable, and there is no tax on the yields of the funds during the savings period (exempt-exempt-taxed principle). entrepreneurs have similar benefi t rules, but they have fl exibility in declaring the amount of labour income and thereby can infl uence the paid contributions and accrued benefi ts. in addition, government supports their pensions. the key features of the current earnings-related pension system are universality and uniformity. policy changes are effective, because the rules apply to almost everyone, and the fi rst-pillar benefi ts cover a large share of the incomes of the retired population. for those whose earnings-related pensions are small, the pensions-tested tax-fi nanced national pension tops up the income. guarantee pensions ensure the minimum level of income. low-income pensioners are also eligible for a housing allowance. the assessment of the performance of the pension system requires a characterisation of its goals. in an agreement on the main features of the pension reform, the social partners set a smooth development of the contribution rates, long-term protection of the benefi ts and ensured fi nancing as the targets (social partners, ). this statement refl ects the reality well: even though the system is based on the principle of defi ned benefi ts, the goals of constant contributions and fair burden sharing between generations have high priority. the aims of the basic pensions are harder to clarify. national pensions and guaranteed pensions are indexed to consumer prices, which means that their development forum government permanently. fertility risks are less important for schemes with individual or cohort-specifi c pre-funding. another, more controversial possibility would be to add a link between the number of children raised and the amount of pension accrued at the individual level (sinn, ) . another trend that possibly weakens the tax and contribution bases is the potential fall in labour income caused by technological development. robotisation and digitalisation infl uence the relative use of labour and capital in production, factor income shares and possibly also unemployment (acemoglu et al., ) . a related trend that is already observable in the finnish labour market is the polarisation of jobs and wages. even though there are large uncertainties about the future development of these trends, their potential infl uence on wages and pensions may be signifi cant. an essential issue in fi nancial sustainability of a pay-asyou-go fi nanced pension system is the link between labour income and accrued pensions. if it is tight, a fall in the total wage bill also reduces pension accruals and finally pension expenditure. the challenge is to fi nance the pensions in payment during the time gap between the immediate realisation of lower contribution income and the future decline in paid pensions. third topic that has recently received renewed attention is the interaction of old age pensions and socio-economic differences in life expectancy. well-educated people, who have higher wage income and larger pensions, live longer and benefi t from old age pensions more. moreover, an increase in the statutory retirement age means that the share of one's lifetime as pensioner declines more for the less educated. this is seen as unfair (sánchez-romero et al., ) . the average working careers of less-educated workers, on the other hand, end earlier, and there is often a period of disability or unemployment before old age retirement. therefore, the realised redistribution depends strongly on the income available after early retirement compared to the old age pension. in the case of finland, a simulation study showed that the average welfare of the less educated does not decline when the retirement age increases (lassila et al., ) . more generally, the main emphasis should be put on reducing the life expectancy differences instead of requiring poorly specifi ed socio-economically adjusted retirement ages. a fourth recent trend, which infl uences especially prefunded pension schemes, is the low interest rate of lowrisk government bonds. in pre-funded defi ned contribu-is almost three times higher than the improvement in the total employment rate. it is very likely that the growth will continue at a rapid pace due to the rising statutory retirement age. the real rate of returns to pension funds has been reasonably high after the investment policies were liberalised ( % in - ) . the low riskless interest rate has boosted asset values and risk premiums have grown, compensating the decline in interest income in recent years. the returns have been somewhat higher in the public sector buffer funds, where risk-taking is not restricted by solvency rules. history shows that demographic development is diffi cult to project in the long term. as population projections are important for the sustainability of pay-as-you-go fi nanced defi ned benefi t pensions, it is useful to assess the uncertainty involved. analysis performed using the stochastic population projections as inputs in an economic model shows that the finnish idea of linking both pensions and the retirement age to life expectancy can manage longevity uncertainty very well. longer working life helps to mitigate the replacement rate decline at the same time as the fi nancial sustainability of both the pension system and the general government is improved (lassila and valkonen, ) . the other demographic and economic risks are carried by the contribution rate in finland, at least if their realisation does not trigger pension reforms. the decreased contribution base requires that the contributions remain higher until the generations that have accrued less pension rights retire. therefore, an observed reduction in the sum of wages and salaries is more problematic with a higher interest rate and lower future growth of contributions. realisation of the risks related to the yield of the pension funds tend to increase contribution rates when the funds are used to pay pensions. the hottest topic of the current pension discussion in finland is the rapid fall of the fertility rate during the past ten years. as there has been no decline in the amount of public resources used to support families by income transfers and services, and the employment rates of the young adults have improved, the reasons behind the declining number of births is not likely to be economic. lack of information about the underlying causes means that there is also large uncertainty about the recovery of fertility and the effi ciency of possible policies to promote it. the policy makers must consider the possibility that the fall in fertility weakens the fi nances of the pension scheme and general the main lesson to be learned from the history and the performance of the finnish pension system is that resiliency can be achieved in two ways. one is a preparedness to make pension reforms, whenever fi nancial or social sustainability are at risk. another is to agree beforehand on rules that redistribute the outcomes of the risks in a way that is acceptable. in finland, the increased weight on fi nancial sustainability and intergenerational fairness in the decisionmaking of the social partners has enabled implementation of balanced reforms, where excessively generous early retirement schemes have been abolished and the link between the wages earned and pensions accrued is strengthened. a key feature is also the new rules that promote longer working lives as a response to increased life expectancy. in general, optimal risk sharing between generations is diffi cult to defi ne. we observe the outcome of the interaction of current pension rules and realised demographic and economic risks but know little about the alternatives. one way of investigating risk sharing is to use stochastic simulations, which describe the outcomes of the current and alternative rules in hundreds of demographic and economic futures. this method provides a set of choices for policymakers. if the pension system is reformed when required instead of investing in risk sharing rules, the system would benefi t from a practice that triggers automatic adjustments to benefi ts and contributions until a reformed scheme takes effect. such a rule would speed up the adjustments processes. tion schemes, the low yield means that the adequacy of pensions is at risk. in pre-funded defi ned benefi t schemes, the contributions are increased either immediately due to solvency issues, or later when the funds are used to pay pensions. the finnish private sector pension institutes have a unique solvency rule that allows a decline in the pre-funded share of the accrued pension liability when stock market prices fall. it has been suggested that this share should be enlarged to allow a riskier investment policy as a response to the low interest rates. this would improve the average return on the funds and mitigate potential problems because of solvency requirements (such as the forced sale of risky assets during recessions), but it increases the variation in the contribution rate, when the funds are used to pay pensions. the covid- crisis weakened the fi nancial sustainability of the pension system markedly, but is not expected to result in an abandonment of the system's basic principles. the social partners reacted to the crisis by suggesting a temporary . percentage point cut in the employer's pension contribution rate. this was accepted by the government. the reduction will be compensated during the - period by higher contributions. the finnish pension system has yet to solve some issues related to effi ciency and risk sharing, yet it has many features that serve as an example of a well-defi ned and robust way to ensure old age security at reasonable costs. the most urgent challenge is to share the fi scal consequences of lower fertility fairly between generations. the current pre-funding alleviates the problems somewhat, but the risk of a large jump in contribution rates is too high. a rules-based way of improving intergenerational fairness would be to establish a link between the prefunding rate and the fertility rate. a more precise instrument would be a link between the accrual of pensions and the fertility rate of a cohort. there is some room for diminishing pension expenditure by removing poorly justifi ed elements. accrual of earnings-related old age pensions from periods when the individual does not pay contributions is one of them. it is the manifestation of a tendency to introduce redistribution in all parts of the tax and benefi t system, also benefi tting those who are well-off in terms of lifetime income. another discretionary policy that would support overall fi nancial sustainability would be to increase the lowest retirement age before implementing the link to longevity. competing with robots: firm-level evidence from france työeläkeuudistus : vaikutukset työuriin, tulonjakoon ja julkisen talouden kestävyyteen, publications of the government´s analysis longevity, working lives and public finances redistributive effects of different pension systems when longevity varies by socioeconomic status europe's demographic defi cit a plea for a child pension system sopimus vuoden työeläkeuudistuksesta statutory pensions in finland: long-term projections , finnish centre for pensions key: cord- -caxz z authors: roberge, raymond j.; coca, aitor; williams, w. jon; powell, jeffrey b.; palmiero, andrew j. title: reusable elastomeric air-purifying respirators: physiologic impact on health care workers date: - - journal: am j infect control doi: . /j.ajic. . . sha: doc_id: cord_uid: caxz z background: elastomeric air-purifying respirators offer the benefit of reusability, but their physiological impact on health care workers is unknown. methods: ten health care workers exercised at health care-associated work rates wearing an elastomeric air-purifying respirator. mixed inhalation/exhalation respirator dead space gases (oxygen, carbon dioxide) were sampled, and physiological parameters were monitored (heart rate, breathing rate, tidal volume, minute volume, oxygen saturation, transcutaneous carbon dioxide). numerical rating scales were used to evaluate comfort and exertion. results: compared with controls (no respirator), significant decreases in the breathing rate at both work rates (p < . ) and increases in tidal volume at the lower work rate (p < . ) were noted with respirator use. approximately half the subjects had transcutaneous carbon dioxide levels above the upper limit of normal after hour of use. although well tolerated, comfort was negatively impacted by elastomeric air-purifying respirators wear. conclusion: reusable elastomeric air-purifying respirators impose little additional physiological burden over the course of hour at usual health care work rates. however, the potential for carbon dioxide retention in a significant proportion of users exists and requires further investigation. the current pandemic influenza and previous experience with other respiratory infectious outbreaks (eg, avian influenza, severe acute respiratory syndrome) have raised concerns about the availability of disposable n filtering face piece respirators (n ffrs). given the very real possibility of n ffr shortages, elastomeric air-purifying respirators (eaprs) for health care workers (hcws) have been suggested as one alternative. these are reusable, air-purifying respirators with face pieces made of pliable materials (eg, silicone, rubber, plastic) that employ or particulate filters and come in full face piece or half-mask models, of which the latter is the more commonly used in health care. compared with disposable n ffrs, eaprs offer advantages that include improved face seal (for some wearers), easier donning and doffing, enhanced user seal check capability, ability of the face piece to be decontaminated multiple times, capacity for use by single or multiple hcws, and potential cost savings during a pandemic. [ ] [ ] [ ] [ ] widespread use of eaprs in the health care industry has not occurred, and little is known about their physiological impact on hcws. this study, part of a larger investigation of multiple types of respiratory protection equipment that was carried out over months, was undertaken to determine the physiological burden imposed on hcws when wearing an eapr. ten hcws ( women, men), none of whom had previously used an eapr, were recruited. demographic variable means included the following: age, . years; body weight, . kg; height, . cm; and body mass index, . . nine subjects had never smoked, and subject had not smoked in . year ( pack year smoking history). the study was approved by the national institute for occupational safety and health's human subject review board, and all subjects provided oral and written informed consent. physiological parameters (heart rate, breathing rate, tidal volume) were monitored with the lifeshirt Ò system (vivometrics, ventura, ca), a lightweight spandex vest incorporating physiological sensors and circumferential respiratory inductive plethysmography (rip) bands. minute ventilation was calculated as the product of breathing rate tidal volume. the lifeshirt Ò was calibrated against a fixed volume immediately prior to each trial. oxygen and carbon dioxide concentrations (percentage) in the eapr dead space were sampled at samples/second (total sampling volume of ml/ min) via a -mm internal diameter sampling line attached to a port in the eapr face piece (positioned equidistant between nares and mouth) that directed samples to gas analyzers (aei technologies, naperville, il). the gas analyzers were calibrated before each trial with gas mixtures weighed into the cylinder using a balance that has been calibrated with weights that are certified to the national institute of standards and technology standards. continuous oxygen saturation and transcutaneous carbon dioxide values were obtained with the tosca monitor (radiometer, copenhagen, dk), a heated ( c) combination pulse oximeter and severinghaus-type pco sensor that is earlobe mounted. the unit was calibrated over a -minute period immediately prior to use. a single model eapr (north ; north safety, providence, ri) that incorporates p- filters was selected for the study because it had previously been shown to be well tolerated by hcws (fig ) . to ensure proper fit, quantitative respirator fit testing was carried out with the portacount Ò plus (tsi, shoreview, mn). all subjects attained fit factors $ (ie, ratio of ambient particles to within-face piece particles), indicating # % leakage, the level required by the occupational health and safety administration for half mask respirators. subjects donned the lifeshirt Ò and were tested in athletic shorts, tee shirts, and athletic shoes (no headgear of any type [eg, caps, head nets, or others] was worn). the eapr was donned according to the manufacturer's instructions, negative and positive user seal checks were carried out with the sample line pinched off, and the tosca sensor was attached to the left earlobe. subjects were exercised for hour (cumulative length of respiratory protective equipment use per shift by nursing staff ) in a randomized fashion at each of treadmill rates representative of hcw activities that have been used in other studies , : ( ) . mph ( . km/h) treadmill speed ( % grade) that equates to stationary work (eg, writing nursing notes, using a telephone, and others) and ( ) . mph ( . km/h) treadmill speed ( % grade) that equates to some bedside nursing patient care activities. data were compared to -minute control values (no eapr use) for the same subjects, at the same randomized work rates, and obtained no more than weeks prior ( -minute values were considered valid for control purposes because, at relatively low intensity steady state exercise, steady state respiratory parameters are achieved in - minutes in healthy subjects , ). numerical rating scales (ie, modified borg rating of perceived exertion [numerical range, - ; least to most exertion ]; modified perceived comfort scale [numerical range, - ; most comfortable to least comfortable ]) were utilized for subjective evaluations of exertion and comfort. speaking was allowed ad lib by subjects throughout the trials to mimic hcw communicating with staff, patients, and visitors. at the end of each trial, subjects filled out questionnaires related to any subjective sensations experienced (eg, facial heat, sweating, and others) or design features (pinching, odor, and others) causing discomfort. eaprs were weighed pretrial and post-trial to determine moisture retention. a new eapr was utilized for each of the sessions, and there was a minimum -minute respite between sessions. the study laboratory average temperature was . c (range, . c - . c) and the relative humidity averaged . % (range, . %- . %). all physiological data and respirator dead space co and o data are reported as means (standard deviation). the time of the sessions is hour, and all variables are reported as mean -minute values at time increments ( , , , , minutes [tables and ]). one-hour averages were used for the statistical analysis because no significant changes over time were observed at the individual time increments. to assess differences between the eapr and controls at the intensity levels during hour of exercise, a -way ( conditions) repeated measures analysis of variance (anova) was performed. to determine differences for physiological variables, repeated-measures anovas for oxygen saturation, partial pressure of transcutaneous carbon dioxide, breathing rate, tidal volume, minute volume, and heart rate were performed. significant differences were further analyzed utilizing pair-wise comparisons tests with least significant differences adjustments with the a level set at p . . paired t tests were performed to examine respirator dead space oxygen and carbon dioxide responses to eapr at the exercise intensities. exertion scores, comfort scores, and eapr weights were analyzed by paired t tests. spss version . (spss, inc., chicago, il) was used for statistical analyses. all subjects were able to complete all trials. compared with controls, the eapr resulted in significant decreases in breathing rate at both work rates and significantly increased tidal volume at the . -mph work rate; otherwise, there were no statistically significant differences in measured physiological variables (tables and ) there were no significant differences in mean mixed inhalation/exhalation respirator dead space carbon dioxide concentrations at . mph and . mph (p . ) or respirator dead space oxygen concentrations at . mph or . mph (p . ) ( table ). there were no significant differences between controls and eapr in mean exertion scores at . mph (p . ) and . mph (p . ), mean comfort scores (p . for both comparisons), or eapr moisture retention (p . ) ( table ) . subjective complaints and eapr features associated with discomfort are listed in table . the study data indicate that the use of an eapr by healthy hcws, over hour at work rates associated with the health care environment, was associated with statistically significant decreases in the breathing rate at . mph (p . ) and . mph (p . ) that was compensated by a significant increase in the tidal volume at . mph (p . ) and nonsignificant increase at . mph (p . ) compared with controls (table ) . this is not unexpected because all respirators alter breathing patterns, and the increased ventilation associated with the (generally) greater dead space of the eapr compared with ffrs (eg, n ffr, and others) usually employed by hcws, favors an increase in tidal volume over breathing rate because it is more efficient from an energy standpoint. a recent review concluded that respirator use has little impact on minute volume during resting or low-intensity work conditions like those normally encountered in health care environments. mean absolute increases in transcutaneous carbon dioxide with the eapr at . mph ( . mm hg) and . mph ( . mm hg) were not significantly different from controls (p . , p . , respectively). of concern is the finding that mean transcutaneous carbon dioxide levels, averaged over the course of the last minutes of the eapr use, were elevated (ie, . mm hg) in of subjects at the . -mph work rate (range, - mm hg) and of subjects at the . -mph work rate (range, . - . mm hg), despite the eapr being equipped with an exhalation valve that presumably allows for a smaller proportion of the exhaled breath (and associated carbon dioxide) to be retained in the respirator dead space (all subjects were asymptomatic of hypercapnia). furthermore, at the work rates, the mean mixed inhalation/exhalation respirator dead space oxygen concentrations ( . %, . %, respectively) and respirator dead space carbon dioxide concentrations ( . %, . %, respectively) did not meet occupational health and safety administration ambient workplace standards (ie, , . % is considered oxygen deficient; maximum . % carbon dioxide as an -hour time weighted average), although these standards apply to the workplace, not to respirators. oxygen saturation was not adversely affected. nonetheless, this raises concerns that extended continuous eapr wear (. hour) might lead to further increases in transcutaneous carbon dioxide that could be deleterious to the wearer. also, the impact of mild-to-moderate eaprassociated increased retention of carbon dioxide upon specific subgroups of hcws who might be more susceptible to hypercapnia (eg, pregnant, asthmatics, and others) needs to be considered. although the use of other air-purifying respirators (ie, gas masks) for upwards of hours by pregnant women in active labor without adverse effects on mother or fetus has been reported, as has tolerance to eapr use by controlled asthmatics over short periods of mild-to-moderate work activities, data are scarce overall. comfort is an important determinant of compliance with the use of respiratory protective equipment. in the current study, mean comfort scores with the eapr were low (indicating less discomfort) and were not significantly different from controls at either work rate, suggesting that eaprs are reasonably comfortable. part of this comfort may be related to the low exertion work rates employed in this study, as supported by the fact that no significant differences were noted in the (low) mean exertion scores reported when comparing controls and eapr use at either work rate. furthermore, recent findings on hcws respirator tolerance (a measure of comfort) reported that the same model of an eapr as used in the current study was tolerated, on average, for . hours of use. nonetheless, numerous complaints were offered by the current study subjects regarding subjective symptoms and design features ( table ) that lend some credence to other recent findings that an eapr, although tolerable, has a greater adverse subjective impact on wearers than n ffrs. moisture retention in respiratory protective equipment has been anecdotally suggested as a possible mechanism for increased respirator breathing resistance with prolonged use because of trapping of moisture in filter pores , , but has not been subjected to scientific scrutiny of any significant degree. although no significant differences in moisture retention were noted at the work rates (p . ), we did not perform airway pressure measurements and cannot comment on any physiological effect of the moisture retention. we observed that there was significant moisture on the inner surface of the eapr, including the exhalation valve, no doubt related to the relatively nonporous nature of the materials. limitations of the current study include the relatively small sample size (n ). there are many differences between this model and the many eaprs available on the market with respect to materials (eg, silicone, rubber, plastic), price, size, weight, tethering device configuration, filters and performance so that we are unable to generalize our findings to other eaprs. the study subjects had no prior experience with an eapr, and that could have negatively impacted performance, but this may be a more plausible study group given that most hcws have not had experience with eaprs. the use of rip for ventilation data is subject to intra-and interpersonal variability and is not as reliable as standard laboratory monitoring equipment (eg, spirometer, pneumotachygraph), but refinements in rip have led to improved accuracy in recent exercise studies. , similarly, transcutaneous carbon dioxide levels are not as precise as arterial measurements, but improvements in sensors have led to greater precision, , and this technique is not discomforting to the subject and avoids needle puncture-associated complications. last, the current study was not carried out in a health care facility; however, laboratory studies have been suggested as actually representing the upper boundary of study parameter measurements. compared with controls over the course of hour at work rates associated with the health care environment, eapr use by hcws results in a lower breathing rate and compensatory higher tidal volume. absolute increases in transcutanous carbon dioxide levels over control values were not statistically significant over the course of hour and not associated with symptomatology of hypercapnia, but variable retention of carbon dioxide occurred in a significant proportion of subjects and is a cause for concern. this will have to be evaluated further in a larger study and over more prolonged periods of continuous use. subjective ratings indicated that, although an eapr was tolerable over hour and not associated with significant perceptions of exertion, comfort was negatively impacted. occupational safety & health administration. pandemic influenza preparedness and response guidance for health care workers and healthcare employers personal respiratory protection against mycobacterium tuberculosis avian influenza pandemic procurement recommendations for the us federal government reusability of facemasks during an influenza pandemic: facing the flu the role of masks in preventing nosocomial transmission of tuberculosis national institute for occupational safety and health. impact of respirator use on co levels and o saturation fy handbook - ; specifications and tolerances for reference standards and field standard: weights and measurements (revised respirator tolerance in health care workers (research letter) occupational safety & health administration. fit testing procedures cfr user seal check procedures (mandatory): cfr : app.b- what do healthcare workers think? a survey of facial protection equipment user preferences compendium of physical activities: an update of activity codes and met intensities effects of wearing n and surgical facemasks on heart rate, thermal stress and subjective sensations evaluation on masks with exhaust valves and with exhaust holes from physiological and subjective responses exercise responses during incremental and high intensity and low intensity steady state exercise in patients with obstructive lung disease and normal control subjects ventilatory patterns during steady state and progressive exercise borg's perceived exertion and pain scales examining an affective aggression framework: weapon and temperature effects on aggressive thoughts, affect, and attitudes the physiological cost of wearing a disposable respirator workplace breathing rates: defining anticipated values and ranges for respirator certification testing physiologic and subjective effects of respirator mask type physiologic effects and measurement of carbon dioxide and oxygen levels during qualitative respirator fit testing does the gas mask jeopardize the fetus? multidomain subjective response to respirator use during simulated work survey and evaluation of modified oxygen delivery devices used for suspected severe acute respiratory syndrome and other high-risk patients in hong kong a century after their introduction, are surgical masks necessary? assoc oper room nurses measurement of exercise ventilation by a portable respiratory inductive plethysmograph monitoring of ventilation during exercise by a portable respiratory inductive plethysmograph use of transcutaneous oxygen and carbon dioxide tensions for assessing indices of gas exchange during exercise testing accuracy of transcutaneous carbon dioxide tension measurements during cardiopulmonary exercise testing. respiration (epub ahead of print) key: cord- -zm ih y authors: gani, raymond; hughes, helen; fleming, douglas; griffin, thomas; medlock, jolyon; leach, steve title: potential impact of antiviral drug use during influenza pandemic date: - - journal: emerg infect dis doi: . /eid . sha: doc_id: cord_uid: zm ih y the recent spread of highly pathogenic strains of avian influenza has highlighted the threat posed by pandemic influenza. in the early phases of a pandemic, the only treatment available would be neuraminidase inhibitors, which many countries are considering stockpiling for pandemic use. we estimate the effect on hospitalization rates of using different antiviral stockpile sizes to treat infection. we estimate that stockpiles that cover %– % of the population would be sufficient to treat most of the clinical cases and could lead to % to % reductions in hospitalizations. substantial reductions in hospitalization could be achieved with smaller antiviral stockpiles if drugs are reserved for persons at high risk. r ecent outbreaks of highly pathogenic avian influenza in poultry in east asia (h n ), canada (h n ), and the netherlands (h n ), and their subsequent transmission to humans, have intensified concern over the emergence of a novel strain of influenza with pandemic potential. three influenza pandemics occurred during the th century, with varying degrees of severity; outcomes ranged from the high levels of illness and death observed during the spanish flu pandemic (estimates of deaths range from to million [ ] ) to the much lower levels observed during the pandemics of and (≈ million deaths each [ ] ). while recognizing that the characteristics of future influenza pandemics are difficult to predict, the world health organization (who) has recommended that nations prepare pandemic contingency plans ( ) . several have been drafted, and some have been published ( ) ( ) ( ) ( ) , although all are subject to continuous refinement. surveillance, on both a local and global scale, will enable policy makers and practitioners to act during the early phases of a pandemic. however, the likely rapid global spread of a pandemic strain will limit the time available to implement appropriate mitigating strategies, and preemptive contingency planning is needed. a number of intervention strategies can reduce the impact of influenza pandemics. during interpandemic years, influenza vaccination is used to reduce deaths and disease. however, vaccine is unlikely to be available in time or in sufficient quantities for use during a pandemic ( , ) . other, nontherapeutic, disease control options may be used, such as those used during the outbreak of severe acute respiratory syndrome ( ) . however, groups of antiviral drugs are available for the treatment and prophylaxis of influenza. these are the adamantanes (amantadine and rimantadine) and the neuraminidase inhibitors (oseltamivir and zanamivir). the adamantanes may be effective against pandemic strains, but concern exists about adverse reactions and the development of antiviral resistance. resistance to amantadine has been demonstrated in a number of avian h strains ( ) and its use for treatment of influenza is not recommended ( ) . the neuraminidase inhibitors (nis) reduce the period of symptomatic illness from both influenza a and b viruses ( ) and both are recommended for use in the united kingdom for treatment of at-risk adults who are able to begin treatment within hours of onset of symptoms. oseltamivir is also recommended for the treatment of atrisk children > months of age ( ) . the development of antiviral resistance has been reported for nis, particularly related to oseltamivir use in children ( ) , although current evidence suggests that resistant strains are pathogenically weakened ( ) . the use of nis for treatment of pandemic influenza remains an option since they may improve individual disease outcomes and the effect of the disease in the population. an influenza pandemic is likely to increase demands on healthcare providers, especially in hospitals. except in japan, current levels of ni use are low. any strategy involving ni use would require stockpiles of these drugs. the potential use of antiviral agents for prophylaxis has been investigated elsewhere and may be of greatest use in the earliest phases of a pandemic to retard the spread of the virus ( , ) . earlier pandemic influenza modeling studies have also focused on the economic effect of vaccination ( ) and the use of ni prophylaxis for disease control ( ) . we assessed the potential effect of using nis for treatment on the estimated number of influenza-related hospitalizations likely to occur during a pandemic. unlike in previous studies ( ) , we have also taken into account the reduction in infectivity that antiviral treatment may have on community transmission. our models focused on using nis to treat different age and risk groups and the potential effects treatment might have on influenza hospitalizations. these effects have been quantified by using the mathematical model described in the online appendix (available from http://www.cdc.gov/ ncdod/eid/vol no / - _app.htm). the length of the latent, noninfectious period was assumed to be days ( ) , and the infectious period was assumed to be days ( , ) . hospitalization rates for the baseline scenario were calculated by using data from interpandemic influenza and are given for different and age risk groups (table ) . to be effective, ni treatment must be administered within hours of symptom onset. the efficacy of ni treatment appears to prevent % of hospitalizations, mirroring efficacy rates against developing complications; this efficacy rate is approximately the same for oseltamivir and zanamivir ( ) . symptoms were also reduced by ≈ . days; treatment was assumed to produce the same decrease in the infectious period. the population was stratified as for seasonal influenza; persons were considered to be either at high risk for severe outcome or at low risk ( ) . the at-risk group included those with chronic respiratory disease, chronic heart disease, chronic renal failure, diabetes mellitus, and immunosuppression; this group also included all persons living in long-term care facilities, such as nursing homes ( ) , and all those > years of age ( ) . demographic data used in the model were based on age-specific distribution of the uk population (office for national statistics, http://www.statistics.gov.uk). the model was used to simulate a number of scenarios, on the basis of contingency plans and previous pandemics, to investigate the effect of targeting nis to different age and risk groups on the expected number of hospitalizations during a pandemic. the baseline scenario for this study was that advocated by who ( ) and was also used previously by meltzer et al. ( ) . this scenario assumes a clinical attack rate, in the absence of interventions, of % of the population, which occurs during a single wave. assuming that half of infections are nonclinical or asymptomatic (i.e., a serologic attack rate across the population of %) ( ), a value for the basic reproduction number, r , of . can be calculated. when these parameters are used in the model in the online appendix, the effect of different-sized antiviral stockpiles on the overall clinical attack rate can be estimated. the outputs from the first set of simulations are shown in figure . the baseline scenario is shown alongside a range of other clinical attack rates ( %- %) (i.e., varying r from . to . ) in the absence of interventions. for these scenarios, antiviral treatment is assumed to be possible within hours of onset for all symptomatic patients until the stockpile is exhausted, with the exception of those < year of age, who are not treated at any stage (treatment for this age group is contraindicated [ ] ). the points on the curves in figure , where the gradients change from vertical to horizontal, indicate the points at which the stockpile is sufficient to treat all patients; increasing the stockpile size would produce no additional depicted are clinical attack rates before interventions of %, %, %, %, and %, with corresponding values for the basic reproduction number (r ) of . , . , . , . , and . respectively. the precipitous decreases observed with the % and % attack rates result at the points at which the stockpile becomes large enough to last long enough to prevent a recrudescence of the epidemic by suppressing the effective reproduction number. benefit and would therefore result in a surplus of antiviral treatments. for the baseline scenario, a stockpile large enough to treat % of the population (i.e., a % stockpile) would be sufficient to treat all patients, even if the clinical attack rate in the absence of treatment is %. this difference is due to a reduction in the effective reproduction number of the disease, r ε , caused by shortening the infectious period of those treated by . days. across the different attack rates, stockpiles sufficient to treat < % of the population are unlikely to result in major changes to disease dynamics. outputs are most sensitive to the clinical attack rate when the reduction in the infection period caused by treatment is sufficient to bring r ε < . when r ε is < , the number of secondary cases produced by each person is < , and incidence, therefore, decreases. the value of r ε can be calculated as where s is the proportion of the population susceptible. with treatment, this equation can be rewritten as where i t is the decrease in the infectious period due to treatment, i p the infectious period, and c i the proportion of infections in each of the different population subgroups, i, that are treated. for the scenarios in figure , i t = . days, i p = . days and c i = . for all groups except those < year of age, who only constitute . % of the population. therefore, the term within the brackets for this scenario can be calculated as . . at the start of the pandemic, s is assumed to be ; therefore, if r is < . , the outbreak can be controlled by treating all patients. for pandemics in which r is > . , depletion of susceptible persons through infection is also required before r ε decreases to < , which is equivalent to s = ( . r ) - . the effect of different treatment strategies on hospitalization rates was generated from the baseline scenario: treating all patients, only at-risk groups, only children and the elderly ( - and > years of age), and only the working population ( - years of age). these scenarios were of potential interest to public health planners; outputs are shown in figure . given a large enough stockpile, the best option to minimize hospitalizations would be to treat all patients; for this scenario, a % antiviral coverage would reduce hospitalizations by up to %. an alternative strategy of treating the whole working population reduces the hospitalization rate by up to % but requires a similar antiviral stockpile size, and treating the working population consistently fails to reduce the number of hospitalizations below the number that would be expected if everyone were treated, regardless of stockpile size. this increase is because the hospitalization rate for the working population is less than the average in the population and also because treating a smaller proportion of the population has less effect on the overall transmission rate. for stockpile sizes only large enough to treat < % of the population, the best strategy would be to treat at-risk groups; this strategy is also best for stockpile sizes up to %, with hospitalizations at this level reduced by up to %. for stockpile sizes from % to %, the best strategy is to treat children and the elderly (reducing hospitalizations by up to %) and for stockpile sizes > %, to treat everyone. the optimum treatment strategy is therefore dependent on treating those at highest risk for hospitalization. the simulations for the baseline scenario were based on a uniform age-specific attack rate and on age-and risk-specific hospitalization rates from interpandemic years because of the uncertainty over the precise characteristics of a future pandemic. since the age-specific clinical attack rate has varied between pandemics, we repeated the analysis above, as far as possible, using the age-specific attack rates from previous pandemics ( - ) ( table ) for comparison with the baseline scenario. the uk pandemic began with imported cases in july ; deaths peaked in november , with a reported overall clinical attack rate of % ( ) . the proportion of infections resulting in clinical illness was calculated from a small serologic survey of general practitioners; only % of the general practitioners surveyed with a positive antibody titer actually had symptoms ( ) . the serologic attack rate was calculated as %, which would require r = . . the epidemic curve that this figure would generate is shown in figure a , with the curve scaled to fit the epidemic curve for deaths ( ) . the only additional change from the baseline scenario is the hospitalization rate, which was reported to be / , population ( ) . using the age-specific attack rates for (table ) in the model, we scaled hospitalization rates to achieve an overall hospitalization rate of / , ( table ) . the results ( figure b) show that a %- % antiviral stockpile would be sufficient to treat all patients during the first wave, a figure that is larger than that seen for the baseline scenario, as both the clinical and serologic clinical attack rates were higher. however, qualitatively, the results are similar in spite of the differences in attack rates between different age groups. with a stockpile as large as %- %, an estimated reduction in hospitalizations of ≈ % could be expected. as in the baseline scenario, effective targeting of smaller stockpiles to at-risk groups can also be used to produce large reductions in hospitalization rates. for stockpiles < %, the best strategy is to treat those at risk, which results in a reduction of %. for stockpiles sizes from % to %, the best strategy is to treat the young and elderly, which results in a % reduction. the highest reduction from treating the working population is % and remains a suboptimal strategy for any stockpile size. the implications of different treatment strategies on the hospitalization rates with a % stockpile are shown in figure c . strategies with larger proportions of the % stockpile had the greatest effect on the epidemic, steadily delaying, but not diminishing, the peak of hospitalizations. treating only the working population results in a % decrease in hospitalizations, treating all patients results in a % decrease, and treating children and the elderly a % reduction. with each of these strategies, the antiviral stockpile is exhausted before the end of the pandemic, whereas the fourth strategy of treating at-risk groups reduces hospitalizations by % and only requires a % stockpile. therefore, treating those at risk is the most efficient strategy, but further targeting may be considered to avoid surplus treatments. the pandemic was characterized by waves, the first relatively small, occurring from february to april ; the larger wave occurred from november to january ( ) . we predominately considered the second wave. a confounding factor is that a proportion of the population would have been immune because of the first wave. weighting age-specific clinical attack rates ( ( ) . b), estimated hospitalization rates from a simulated pandemic with available parameters from the pandemic, as influenced by stockpile size and treatment strategy. c), impact of treatment strategy on the time course of hospitalizations when the stockpile size is fixed at % of the population, the stockpile is fixed at % of the population and all clinical cases are treated, and when no treatment is administered. overall clinical attack rates for the first and second waves to be % and %, respectively ( ; office for national statistics [http://www.statistics.gov.uk]). the serologic attack rate was derived by fitting the model to the data for the second wave from the royal college of general practitioners (provided by douglas fleming; http://www. rcgp.org.uk); we assumed a similar proportion of asymptomatic cases in both waves. the fit of the model to the data is shown in figure a , from which is derived a % residual immunity from the first wave and a % serologic attack rate for the second wave, which produces an effective reproduction number of . for the second wave. the overall hospitalization rate for the second wave was reported as per , ( ) , and using the age-specific attack rates for in table , we adjusted the values in table to fit this value. the size of the stockpile required to treat all patients is ≈ % (which is relatively small compared to the pandemic because of the lower clinical attack rate), which leads to fewer patients being treated and less reduction in overall transmission. if all persons whose infections resulted in clinical illness (i.e., patients) were treated, the hospitalization rate would drop by ≈ % ( figure b ). for the pandemic, the effects of the different antiviral targeting strategies were different than in the previous scenarios as a result of the different age-specific attack rates, which are shifted more towards the working population (table ) . thus, relatively small stockpiles are required to treat either the at-risk group or the young and elderly group (≈ % for each group), since most patients are in the working population and neither of these groups. for stockpiles of up to %, treating the at-risk group is marginally better than treating the young and the elderly ( % reduction in hospitalization as opposed to %), and for stockpiles > %, treating all clinical patients would be the best strategy. the effects of the different treatment strategies with a % stockpile are shown in figure c . hospitalizations would drop by ≈ % if all patients were treated and by % if the working population were treated; both treatment strategies would lead to the stockpiles' being exhausted. as above, treating those at risk would reduce hospitalizations by %, whereas treating only children and the elderly would reduce hospitalizations by % and only require a % stockpile per group. of these strategies, treating the at-risk groups is the most efficient, but given surplus stockpile, further extension of the groups to be targeted may be considered. the characteristics for the pandemic differ substantially from the other in that distinct waves occurred; the age-specific attack rates were highest for those in their teens, s, and s; and the mortality rates were higher ( ). in addition, age-specific attack rates and mortality rates differed for each of the waves ( ) . modeling based on the pandemic was therefore considerably less straightforward than for the previous pandemics, and an approach was taken to fit the transmission model to each of the waves, separately. no cross-immunity was assumed between different waves since studies suggested only weak effects; indeed, some studies suggested greater susceptibility in the third wave if a person had had influenza in the first pandemic wave ( ) . clinical attack rates were calculated from reported weekly mortality data and clinical case-fatality rates ( ) . serologic attack rates were then fitted separately to each of the curves ( figure ), from which values of r = . , . , and . were derived from each of the respective waves. the estimate for the second wave is lower than other estimates of ≈ ( ) derived from us cities and is probably because our estimates were derived from data from throughout england and wales, thereby incorporating spatial heterogeneity. since hospitalization rates were not available for any of the waves, we considered the effect of antiviral treatment on death. the potential efficacy of antiviral treatments in preventing death between waves may have differed, but it was assumed to provide % protection against death. this estimate was based on the assumption that % protection from the more serious outcomes of influenza can be translated to equivalent protection from death ( ) . a pandemic with the characteristics of that in would, without antiviral treatment, produce an estimated number of deaths equivalent to ≈ . % of the population across all waves. however, a % stockpile sufficient to treat all patients across the waves would result in ≈ % reduction in deaths. with a smaller stockpile of %, the reduction in deaths was only % because the stockpile becomes exhausted during the second wave, before most of the deaths occur ( figure ). the baseline scenario with an overall clinical attack rate of %, as currently advised by who ( ), is roughly in accordance with data from previous pandemics. the general conclusion from our study is that antiviral treatments for % to % of the population are likely to be sufficient to treat all patients for pandemics with characteristics that have been observed to date. the size of the stockpile required will depend on the clinical attack rate of the pandemic and the r value. however, with smaller stockpile sizes, substantial reductions in hospitalizations can be achieved through targeting. for the smallest stockpiles, the best strategy was to treat conventional influenza at-risk groups. treating the young and elderly is only slightly less effective. treating the working population may have benefits beyond reducing hospitalizations, such as reducing illness-related absenteeism, but it consistently fails to be the best strategy for reducing hospitalizations. for large stockpiles, treating all patients is consistently the best strategy in reducing hospitalization and transmission. when all patients are treated, the marginal effect of treatment on reduced transmission increases with the number of patients treated, until all patients have been treated. further studies regarding the effects of antiviral treatments would improve the robustness of the parameter estimates. in particular, better estimates on the efficacy of ni treatment against hospitalization and death rates for different age and risk groups and estimates on the reduction in the infectious period are required. also, the issue of antiviral resistance needs to be resolved since it could compromise ni effectiveness. the scenarios above assume that clinical patients were treated within hours of onset of symptoms; however, in reality, some cases will be diagnosed or reported too late, and other patients will be administered drugs mistakenly. to maximize the benefits of antiviral treatment, patients should be strongly encouraged to seek treatment and treatment should be supported by sound clinical judgment and ( ) . b), estimated hospitalization rates from a simulated pandemic with available parameters from the pandemic as influenced by stockpile size and treatment strategy. c), impact of treatment strategy on the time course of hospitalizations when the stockpile size is fixed at % of the population, the stockpile is fixed at % of the population and all clinical cases are treated, and when no treatment is administered. diagnostic capability. if high levels of treatment are not achievable, disproportionately higher hospitalization rates than those calculated here would ensue. in addition, identifying groups with higher transmission rates for targeting treatment would result in greater reductions in transmission than reported here. assessments will need to be recalculated in the earliest phases of a pandemic with real-time data to confirm or update the assumptions used and ensure that the model parameters are appropriate. therefore, were a pandemic to occur, intensive analysis of its dynamics would be required at its start. updating the accounts: global mortality of the - "spanish" influenza pandemic the epidemiology and clinical impact of pandemic influenza world health organization. influenza pandemic plan. the role of who and guidelines for national and regional planning. geneva: the organization influenza pandemic preparedness plan for the united states uk pandemic influenza contingency plan influenza pandemic: preparedness planning in germany canadian pandemic influenza plan, health canada are we ready for pandemic influenza? pandemic influenza and the global vaccine supply evaluation of control measures implemented in the severe acute respiratory syndrome outbreak in beijing amantadine resistance among hemagglutinin subtype strains of avian influenza virus full guidance on the use of zanamivir, national institute for clinical excellence. full guidance on the use of zanamivir, oseltamivir and amantadine for the treatment of influenza the treatment of influenza with antiviral drugs resistant influenza a viruses in children treated with oseltamivir: descriptive study neuraminidase sequence analysis and susceptibilities of influenza virus clinical isolates to zanamivir and oseltamivir tackling the next influenza pandemic tackling the next influenza pandemic: ring prophylaxis may prove useful early on, but is unlikely to be effective or practical to implement once the pandemic is established the economic impact of pandemic influenza in the united states: priorities for intervention containing pandemic influenza with antiviral agents pandemic influenza and healthcare demand in the netherlands: scenario analysis a bayesian mcmc approach to study transmission of influenza: application to household longitudinal data the population at risk in relation to influenza immunisation policy in england and wales. health trends department of health. influenza immunisation. cmo's update influenza: quantifying morbidity and mortality joint public health laboratory service/royal college of general practitioners working group london: her majesty's stationary office influenza - incidence in general practice based on a population survey report on the pandemic of influenza - . london: her majesty's stationary office impact of epidemic type a influenza in a defined adult population transmissibility of pandemic influenza we thank members of the uk department of health steering group for their comments and help with setting model parameters.financial support for this work was provided by the uk health protection agency. the views expressed in this publication are those of the authors and not necessarily those of the health protection agency.dr gani is a mathematical modeler. his research interests are the impact of pandemic influenza and other emerging and reemerging infectious diseases on human populations and assessments of policy options available to mitigate these impacts. key: cord- -vjzfzshh authors: pereira-gómez, marianoel; sanjuán, rafael title: effect of mismatch repair on the mutation rate of bacteriophage ϕx date: - - journal: virus evol doi: . /ve/vev sha: doc_id: cord_uid: vjzfzshh viral mutation rates vary widely in nature, yet the mechanistic and evolutionary determinants of this variability remain unclear. small dna viruses mutate orders of magnitude faster than their hosts despite using host-encoded polymerases for replication, which suggests these viruses may avoid post-replicative repair. supporting this, the genome of bacteriophage ϕx is completely devoid of gatc sequence motifs, which are required for methyl-directed mismatch repair in escherichia coli. here, we show that restoration of the randomly expected number of gatc sites leads to an eightfold reduction in the rate of spontaneous mutation of the phage, without severely impairing its replicative capacity over the short term. however, the efficacy of mismatch repair in the presence of gatc sites is limited by inefficient methylation of the viral dna. therefore, both gatc avoidance and dna under-methylation elevate the mutation rate of the phage relative to that of the host. we also found that the effects of gatc sites on the phage mutation rate vary extensively depending on their specific location within the phage genome. finally, the mutation rate reduction afforded by gatc sites is fully reverted under stress conditions, which up-regulate repair pathways and expression of error-prone host polymerases such as heat and treatment with the base analog -fluorouracil, suggesting that access to repair renders the phage sensitive to stress-induced mutagenesis. mutation is the ultimate source of genetic variation and, therefore, a central evolutionary process. although mutations are required for adaptation, the short-term deleteriousness of most spontaneous mutations should generally favor low mutation rates (sniegowski et al. ) . in theory, the balance between these short-term costs and the long-term benefits for adaptation should produce an evolutionarily optimal, intermediate mutation rate which is dependent on selection strength (orr ; johnson and barton ) . other factors can also determine mutation rate evolution, including the costs of maintaining mechanisms of replication fidelity, population size, and structure, or the topology of the fitness landscape among others (andré and godelle ; clune et al. ; jiang et al. ; lynch ; sung et al. ) . despite this variety of factors, it has been noted that genomic mutation rates stay remarkably constant among dna viruses, bacteria, and unicellular eukaryotes (drake ; drake et al. ) . as a consequence, pernucleotide rates vary by , -fold and inversely with genome size, from - to - mutations per nucleotide per round of copying (m/n/r) (lynch ) . how evolutionary forces have shaped this inverse relationship in such widely different microbial systems and which molecular mechanisms allow for this mutation rate variation remain poorly understood questions. for dna viruses, mutation rates range from - m/n/r in double-stranded (ds) dna viruses such as herpes virus to - m/n/r in single-stranded (ss) dna viruses such as bacteriophage /x , whereas these rates range from - to - m/n/r in rna viruses (sanjuá n et al. ) . a primary determinant of viral mutation rates is replication fidelity, and polymerase variants with altered base-selection specificities have been described in several rna viruses including picornaviruses, alphaviruses, and retroviruses. however, fidelity variants that are not lethal typically alter mutation rates only slightly (pfeiffer and kirkegaard ; arias et al. ; mené ndez-arias ; coffey et al. ; graci et al. ) . the presence of exonuclease proofreading has a stronger effect on viral replication fidelity. all rnadependent polymerases except those of coronaviruses lack ' exonuclease activity, as opposed to virus-encoded dna polymerases, therefore providing a clear basis for the higher mutation rates of rna viruses compared with dna viruses (roberts, bebenek, and kunkel ; steinhauer, domingo, and holland ; mené ndez-arias ; denison et al. ; smith et al. ). in addition to polymerase fidelity, in dna viruses, mutation rates should be determined by their ability to access postreplicative repair. in ssdna bacteriophages such as /x or m , replication is carried out by the escherichia coli dna iii holoenzyme, which exhibits similar fidelity in phage and host templates (fersht ; fersht and knill-jones ) . however, these phages show a mutation rate approximately three orders of magnitude higher than the host (wickner and hurwitz ; raney, delongchamp, and valentine ; cuevas, duffy, and sanjuá n ). the high variability and fast evolution of small eukaryotic dna viruses such as parvoviruses and polyomaviruses similarly suggests elevated rates of spontaneous mutation (duffy, shackelton, and holmes ) . the efficiency of post-replicative repair can be higher than per cent (fijalkowska, schaaper, and jonczyk ) . in e. coli, strand-specific bidirectional methyl-directed mismatch repair (mmr) is performed by the dam/muthls system (jiricny ) . point mutations or small insertion/deletion loops are recognized by muts, which interacts with mutl, leading to activation of the muth endonuclease. the latter recognizes the parental strand by the presence of a methyl group in the adenosine of a gatc sequence motif located on either side of the mismatch, which has been previously added by dam methylase. muth then cleaves the non-methylated daughter strand, which is degraded and re-synthesized (modrich and lahue ; marti, kunz, and fleck ; schofield and hsieh ; li ; fukui ) . strikingly, though, the . kb genome of bacteriophage /x contains no gatc sites, whereas the randomly expected number of such sequences given the /x genome size and base composition is approximately . by impeding dam methylation, the lack of gatc sites therefore avoids a major repair pathway. however, the impact of gatc motifs on the phage mutation rate is still poorly understood. in a previous study (cuevas, pereira-gomez, and sanjuá n ) , we introduced four gatc sequence motifs in the /x genome and found no effects on mutation rate. however, by increasing the number of gatc motifs to seven, we obtained a thirtyfold reduction in mutation rate. furthermore, this effect was reverted in mmrdeficient mutd cells, indicating that the effects of gatc motifs were related to mmr. here, to better explore how mmr avoidance determines the mutation rate of /x , we constructed a /x variant encoding twenty randomly located gatcs with minimal effects on protein sequence. the engineered phage showed an eightfold reduction in spontaneous mutation rate compared with the wild type (wt), yet no obvious growth defects under standard conditions. however, the efficacy of gatc-driven mmr was curtailed by poor methylation of the phage dna, preventing recognition of the parental strand. furthermore, after constructing several mutants in which the number and location of gatc sites were varied, we found that their effects on mutation rate were non-additive and highly variable, with some combinations achieving an up to fiftyfold reduction in mutation rate while others having no effects. the highest efficiencies were shown by some intergenic gatcs, suggesting that steric constrains such as availability of the dna to muth may be important for mmr. finally, we found that the mutation rate reduction afforded by the twenty gatc motifs was fully reverted at c and in the presence of the base analog -fluorouracil ( -fu), two stress factors that promote overexpression of repair-associated error prone polymerases (layton and foster ; malkova and haber ) , thus suggesting that addition of gatc motifs renders the phage sensitive to stress-induced mutagenesis. the e. coli c strain ij was obtained from prof. james j. bull. the gro mutant was provided by prof. bentley a. fane (university of arizona). bacteriophage /x originally obtained from prof. james j. bull (texas university) was adapted to our laboratory conditions by long-term passaging in ij cells (domingo-calap, cuevas, and sanjuá n ) . gatc sites were engineered in the genetic background of this adapted virus, here denoted the wt, which contains no gatcs (genbank accession gq ). the /x dsdna replicative form was purified from infected cultures before lysis using a standard miniprep kit (macherey-nagel), and pg of this dna were used as template for polymerase chain reaction-based mutagenesis using phusion high-fidelity dna polymerase (thermo scientific) and contiguous, divergent, '-phosphorylated primers, of which the reverse primer carried the desired nucleotide substitution. polymerase chain reaction products were circularized with the rapid dna ligation kit (thermo scientific) and used for transfecting competent ij cells by the classical heat-shock method. a single plaque was picked, resuspended lysogeny broth medium, and stored at - c. the presence of each substitution was confirmed by sanger sequencing. this process was iterated until twenty gatc sites were introduced. full-length sequencing of the gatc virus was performed to verify that all mutations were present and that no other changes were introduced. each test consisted of twenty-four independent . ml ij cultures inoculated with the indicated initial number (n ) of plaque forming units (pfu) and incubated in a thermomix shaker (eppendorf) at rpm until n pfu were produced. this growth phase was done under standard conditions ( c), at high temperature ( c), or in the presence of ng/ml -fu ( c) by preincubating cells with -fu min before infection. all titrations were done under the same, standard conditions (ij cells with agar overlay, c, no -fu). n was determined by titrating six of twenty-four random cultures. to score mutants, . ml ( % of the total volume) was titrated on the restrictive e. coli gro strain, a rep mutant where only /x mutants with certain mutations in the n-terminal end of the viral protein a can form plaques (ekechukwu, oberste, and fane ) , the total number of different substitutions leading to the resistance phenotype being t ¼ under our assay conditions (cuevas, duffy, and sanjuá n ) . we estimated the rate m at which gro -resistant mutants appeared using the null-class method, which is based on counting the proportion of cultures showing zero versus at least one mutant. the number of mutations per culture should follow a poisson distribution with parameter k ¼ m(n -n ), such that the expected probability of no mutants in a culture is p ¼ exp[-m(n -n )]. mutation rates per nucleotide per round of copying (m/n/r) were then calculated as m ¼ m/t, where the factor stands for the fact that each base can mutate to three different bases. three independent tests were performed for each mutant, except for the wt, for which fifteen tests were performed. mutation rate estimates for the wt in the presence of -fu ng/ml were taken from a previous work (pereira-gó mez and sanjuá n ). for fluctuation tests performed under stress conditions, we applied a correction for bias in n estimation which may result from increased viral degradation relative to standard conditions. following previous work (bradwell et al. ) , the probability of observing no mutants was recalculated accordingly as where ź quantifies this bias. as an indicator of ź , we determined the relative plating efficiency of the wt virus under the two stress conditions. plating efficiency was slightly increased at c (ź ¼ . . ) and reduced in the presence of ng/ml -fu (ź ¼ . . ). we therefore used the corresponding ź values for calculating mutation rates at c and in the presence of -fu. since the relative plating efficiencies of the gatc virus did not differ significantly from those of the wt (t-test: p > . ), we used the same ź values. q-q plots showed that mutation rate estimates were not normally distributed, whereas normality was satisfied using log-transformed rates. all statistical tests were thus performed using log-transformed rates. the viral exponential growth rate was estimated as r ¼ ln(n / n )/t, where n and n were obtained from the fluctuation test assays, and t is the incubation time in hours. q-q plots indicated that growth rates were normally distributed. the /x dsdna replicative form was quantified using the quant-it picogreen dsdna broad range assay kit (life technologies), and all extracts were brought to the same concentration ( ng/ml). dna from each virus was split into three aliquots, which were treated with xhoi to linearize the genome, with xhoi and dpni to digest methylated gatcs, or with xhoi and mboi (i.e., dpnii) to digest non-methylated gatcs. double digestions were performed according to the manufacturer instructions (thermoscientific). a standard plasmid (pires, clontech) was used as a digestion control (not shown). a monochrome picture of the gel was transformed to an eight-bit image, and the pixel area and intensity of each band were quantified using imagej. given the size and base composition of the /x dna ( , bases, . % t, . % a, . % g, and . % c), the expected number of gatc sequence motifs in its genome is .  .  .  .  , ¼ . . the poisson probability of observing no gatc motifs is extremely low (p ¼ .  - ), thus indicating a strong avoidance of these motifs. to restore gatc usage in /x , we created a mutant phage carrying twenty gatcs by sequential addition of these sites into the wt virus using site-directed mutagenesis (fig. ) . the twenty gatc motifs were evenly distributed throughout the phage genome, the greatest distance between any two consecutive of them being bases and, wherein possible, substitutions were made synonymous to minimize their effects on protein function. given that the dam/muthls system can perform mmr at a distance of up to kb from a gatc (modrich and lahue ) , the number and distribution of the introduced gatcs should allow for efficient mmr in the entire phage genome. to test the effect of gatcs on the viral mutation rate, we performed luria-delbrü ck fluctuation tests for the wt and gatc viruses. to score mutants phenotypically, we used the non-permissive e. coli c mutant gro , which carries a mutation in the dna helicase gene rep that blocks stage iii ssdna synthesis, preventing maturation of the wt phage (ekechukwu, oberste, and fane ) . the phage can overcome this restriction by changing certain amino acid residues in the n-terminal region of protein a, an endonuclease that nicks the negative strand of the supercoiled phage dna, and these protein changes can be conferred by at least seven different nucleotide substitutions (cuevas, duffy, and sanjuá n ) . by growing the virus in permissive cells and performing plaque assays in gro cells to score mutations, we obtained an estimated mutation rate for the wt of ( . . )  - m/n/r, a value consistent with previous studies (raney, delongchamp, and valentine ; cuevas, duffy, and sanjuá n ) . in contrast, the rate of the gatc virus was ( . . )  - m/n/r, revealing a . -fold reduction compared with the wt (t-test: p < . ; table ; fig. a ). the estimated growth rate was similar for the wt (r ¼ . . h - ) and the gatc viruses (r ¼ . . h - ; t-test: p ¼ . ; table ; fig. b ), indicating that these substitutions had no significant impact on short-term viral fitness. these findings confirm our previous results obtained with a mutant phage carrying seven gatc sites (cuevas, pereira-gomez, and sanjuá n ). since mmr relies on the presence of gatcs in the vicinity of the mismatch, addition of gatcs in this region should suffice to yield similarly low mutation rates. on the basis of this, we constructed a virus with four gatcs located between genome positions and , which were within . kb of known groresistance mutations (fig. ) . however, surprisingly, the mutation rate of this four gatc virus was significantly higher than that of the gatc virus (t-test: p ¼ . ) and similar to the wt rate (p ¼ . ). in light of this result and since dam methylation of gatc adenosines is required for mmr, we sought to determine the methylation status of the gatc /x dna. to do so, we purified the dsdna replicative form, linearized it, and treated it with the dpni restriction endonuclease, which selectively digests methylated and hemi-methylated gatcs. although dpni produced restriction bands of the expected size, digestion was only partial (fig. ) . to test whether this could be explained by incomplete dna methylation, we performed the same restriction analysis using mboi, which also recognizes gatc sites but digests them only in their non-methylated form. mboi also produced restriction bands, thus confirming that a fraction of the phage dsdna was not methylated. image analysis indicated that per cent of dna was digested by mboi and thus lacked at least one of the four possible methyl groups, whereas per cent was undigested by dpni, thus lacking all four methyl groups. overall, the similar efficiency shown by dpni and mboi suggests that roughly half of gatc motifs were methylated, although more detailed analyses would be required to reliably infer this fraction. we verified that under-methylation was not due to a dam defect in the host cell, since a standard plasmid grown in the same e. coli strain was fully digested by dpni and fully resistant to mboi (not shown). therefore, these results suggest that, as opposed to plasmid or chromosomal dna, gatc-mediated mmr is not fully efficient in /x because the phage dna is under-methylated. given that protein-coding regions represent approximately per cent of the /x genome, by chance one in twenty figure . /x genetic map and location of the gatc sequence motifs introduced in this study. open reading frames are represented by rectangles (b, k, and e are in different reading frames), and gray bars indicate intergenic regions. each gatc is represented by a dot, and its position is indicated on top. gatc motifs that were synonymous in all reading frames are indicated in blue, whereas those producing amino acid replacements in at least one frame are shown in green (a c produces a k q replacement in gene a and is synonymous in gene k; t g produces a v g replacement in gene a and is synonymous in gene b). mutations falling at intergenic regions are shown in red. the phage has circular dna but is represented linearly for convenience, where by convention the first position corresponds to the last nucleotide of the unique psti site. where t ¼ is the number of substitutions leading to gro resistance. g r ¼ lnðn =n Þ=t, where t is the incubation time in hours. table for details. gatc sites should fall at intergenic regions. to test how gatc location may influence mmr and the phage mutation rate, we created another mutant ( igatc) in which one of the four synonymous substitutions of the above gatc virus was replaced by substitution a g, which was located in the spacer region between genes h and a. the mutation rate of the igatc was ( . . )  - m/n/r, which represents a fiftyfold reduction compared with the wt (t-test: p < . ; table ). therefore, addition of this single intergenic substitution had a dramatic effect on the viral mutation rate, compared with the gatc virus. to further test the effect of intergenic gatcs on mmr, we first created the single mutant a g, which showed a mutation rate five times lower than the wt (t-test: p < . ; table ). this rate was significantly higher than for the igatc virus (t-test: p ¼ . ), showing that the effect of the a g substitution was enhanced by the presence of other, neighboring gatc sites, consistent with the lack of full methylation shown above. then, we constructed two additional intergenic single-gatc viruses located in the region between the h and a genes by introducing the appropriate nucleotide substitutions (fig. ) . the mutation rate of the virus carrying the c g/c a substitutions was fourteen times lower than the wt (t-test: p < . ; table ), whereas substitutions a g/t c were unable to reduce the mutation rate below the wt level (p ¼ . ) despite being located only five bases away from the previous substitutions. therefore, some but not all intergenic gatcs are able to promote mmr, and minute changes in their genome location lead to marked differences in mutation rate. induction of the chaperone-encoding groe operon in response to heat shocks up-regulates the expression of the error-prone dna polymerase iv, which participates in the repair of dsdna breaks under different types of cellular stress, leading to stress-induced mutagenesis (layton and foster ; malkova and haber ) . to address the effects of heat shocks on the /x mutation rate, we performed fluctuation tests at c for the wt and gatc viruses. the mutation rate of the wt was not significantly affected by the temperature shift (t-test: p ¼ . ; table ; fig. a ). in contrast, the mutation rate of the gatc virus was twenty times higher at c than at c (t-test: p < . ) and increased even above the wt level (p ¼ . ). therefore, the effects of gatc sites on the /x mutation rate observed at c were reverted at c. heat drastically reduced the viral growth rate but, whereas the wt and gatc viruses showed similar growth rates at c, the gatc virus grew significantly slower than the wt at c ( . . h - versus . . h - ; t-test: p ¼ . ; table ; fig. b ), suggesting that up-regulation of repair pathways under thermal stress slows down phage replication. to evaluate the effects of another stressor, we treated cells with -fu ( ng/ml) which, in addition to causing mutations directly by base mispairing, -fu inhibits thymidylate synthase, leading to deoxythymidine monophosphate deprivation and, subsequently, to dna strand breaks, induction of the sos dna damage response (ddr), and expression of error-prone dna repair enzymes (ahmad, kirk, and eisenstark ; fonville et al. ) . previously, we showed that this treatment increases the mutation rate of the wt virus by approximately tenfold (domingo-calap, pereira-gomez, and sanjuán ). fluctuation tests in the presence of ng/ml -fu showed that the drug had a more pronounced effect on the mutation rate of the gatc virus, which increased more than a -fold (table ; fig. a ). as a result, the difference in mutation rate between the gatc and wt viruses was fully abolished in the presence of -fu (t-test: p ¼ . ). we have shown that introduction of gatc sites in the /x genome can reduce the spontaneous mutation rate of the phage by up to fiftyfold, indicating that phage dna can undergo mmr if the required sequence motifs are present. the effect of gatc addition is greater than those reported previously in rna viruses, in which high-fidelity polymerase variants selected after serial transfers in the presence of nucleoside analogs typically reduce the viral mutation rate by threefold or less (pfeiffer and kirkegaard ; coffey et al. ) . a similarly modest effect was observed after serial passaging of /x in the presence of -fu (domingo-calap, pereira-gomez, and sanjuá n ). in that case, the anti-mutator phenotype was achieved by a delayed lysis, which increased the viral burst size per cell and thus allowed the phage to expand its population size in fewer rounds of copying (pereira-gó mez and sanjuá n ). in the dsdna bacteriophage t , a series of polymerase variants capable of strongly suppressing the action of chemical mutagens were isolated in early studies (drake et al. ; drake and greening ) . however, high fidelity variants of t polymerase tend to show diminished polymerization rates, therefore negatively impacting viral fitness (mansky and cunningham ) . in e. coli, figure . restriction fragment analysis of the /x replicative dsdna. phage dsdna was purified by standard miniprep as described in the materials and methods section and linearized with xhoi (ø), which recognizes a unique site at position , with xhoi and dpni to cleave methylated or hemi-methylated gatcs, or with xhoi and mboi to cleave non-methylated gatcs. expected (left) and observed (center) restriction fragments for the wt and gatc phage dsdna are shown. lower size fragments (< bp, fig. ) were expected but could not be visualized because the amount of input dna was low. the smear in lanes containing the purified phage dna probably results from degradation of host dna. the contrast of the gel image was enhanced to help visualize bands. right: percent abundance of each dpni and mboi restriction band ( - ). band in the dpni lane indicates the non-methylated dna fraction (i.e., none of the four gatc motifs was methylated), whereas in the mboi lane, this same band indicates the fully methylated fraction (i.e., the four gatc motifs were methylated). bands were quantified as detailed in the materials and methods section using the raw gel image with no contrast enhancement. changes in the a subunit of dna polymerase iii can increase replication fidelity between two-and thirtyfold (fijalkowska, dunn, and schaaper ) . a stronger anti-mutator phenotype was found in the adenine-dependent e. coli mud strain, but latter analyses suggested that this was probably due to poor detection of mutants (schaaper ) . in another study, e. coli clones were isolated with an up to fiftyfold anti-mutator phenotype, but the underlying mechanisms remained undetermined (quinones and piechocki ) . therefore, the magnitude of the mutation rate reduction afforded by the introduction of gatc motifs is similar or higher than those reported previously in other viruses and in bacteria and has a well-defined molecular basis. our results suggest that the /x mutation rate can be modified without significantly impacting viral fitness in the short-term, therefore allowing for evolutionary optimization of the viral mutation rate for long-term adaptability. however, our results also revealed constraints limiting mutation rate evolution, since the effects of gatc addition were lower than expected if mmr were fully efficient (fijalkowska, schaaper, and jonczyk ) . illustrating this, the lowest mutation rate achieved in this study (  - m/n/r) was still two orders of magnitude higher than that of e. coli (drake ; drake et al. ; lee et al. ) . our results suggest that inefficient mmr in /x is at least in part due to the fact that phage dna is under-methylated. full methylation may be impeded by the fast replication of the phage and the transient nature of the dsdna replicative form. cellular dam methylase levels must be tightly regulated, because hypo-and hypermethylation can compromise the ability of the mmr system to distinguish between the parental and daughter dna strands. showing this, both dam deficiency (bale, d'alarcao, and marinus ; marinus ) and overexpression (pukkila et al. ; mcclelland ) have been found to produce mutator phenotypes in e. coli. it is possible that dam methylation levels which are optimal for the host are too low for the phage, due to its fastest replication. this could be tested in future work by infecting dam-overexpressing e. coli c mutants with the gatc phage and determining phage dna methylation levels and mutation rates. assuming that the mmr system can use gatc sites at a distance of up to kb from the mismatch, for a dna showing the randomly expected density of gatcs, there should be approximately four such sites available for each mismatch. for a per cent methylation efficiency, the fraction of non-reparable mismatches would thus be on the order of . ¼ . , implying that the maximum mutation rate reduction achievable by mmr for this methylation efficiency would be / . ¼ seventeenfold. incomplete gatc methylation can hence account for the relatively limited efficacy of mmr in /x . we note that the fiftyfold mutation rate reduction observed for the igatc virus could be achieved with per cent methylation, a value experimentally undistinguishable from the per cent assumed above given that we could not finely quantify the fraction of methylated dna. however, for some gatcs, the efficacy of mmr was clearly below the upper-limit imposed by under-methylation, since the gatc and a g/t c viruses showed no change in mutation rate at all. our results indicate that intergenic gatcs tended to have stronger effects than those located in protein- table for details. coding regions, suggesting other factors curtailing mmr efficiency such as steric availability to muth. as we have shown, though, even two extremely close gatcs can have very different effects on mutation rate, and we lack a model for explaining these differences. the region in which the single intergenic gatcs were placed contains the a promoter and the h terminator. the c g/c a substitution, which had the strongest effect on mutation rate, was located farthest away from the a promoter. we can speculate that, if steric availability of the gatc motif to muth was limited by the transcription machinery, a more distal positioning from actively transcribed regions may allow for more efficient mmr. however, the a g and a g/t c substitutions were located approximately at the same distance of the a promoter. a g/t c was upstream of the promoter, whereas a g was downstream of the promoter and in a palindromic region with a relative high gþc content. as suggested previously, mismatch recognition may depend also on sequence context, increasing its efficiency in regions with higher gc content (jones, wagner, and radman ) . therefore, our results suggest that evolutionary optimization of the mutation rate may not be the sole factor driving gatc avoidance in /x or other enterobacteriophages, since we found that some gatcs had no effect on the viral mutation rate yet are also absent from the wt /x genome. mutation rate elevation can confer faster adaptation to new and stressful environments, and this has been shown to promote the spread of mutator strains in bacteria (leclerc et al. ; sniegowski, gerrish, and lenski ; jolivet-gougeon et al. ) . furthermore, bacteria have evolved the ability to up-regulate their mutation rates in response to stress by expressing of error-prone polymerases (rosenberg ; galhardo, hastings, and rosenberg ) . however, we have shown that gatc avoidance does not appear to increase the /x mutation rate under stress conditions, thus undermining the potential evolutionary advantage of such avoidance. it has been shown that phage yields tend to decrease in dam -muth þ suggesting that, in the absence of methylation, muth cleaves some gatc sites non-specifically and may also interfere with other stages of the infection cycle such as replication or encapsidation (deschavanne and radman ) . this would directly counterselect gatc sequence motifs in the phage. although in our experimental setting, we did not detect a significant deleterious fitness effect associated with gatcs in the absence of stress, such effects may potentially take place in other environments not assayed here. therefore, the evolutionary forces shaping gatc avoidance remain unclear, and may result from the joint action of several factors. interestingly, dna repair pathways may also be relevant to virus-host interactions in eukaryotes. vertebrate dna viruses have been shown to interact with the evolutionarily conserved ddr, which is aimed at detecting lesions in dna, initiating cell cycle arrest, and promoting repair. for instance, in hepadnaviruses, the synthesis of replication-competent covalently closed circular dna requires the participation of ku , a component of non-homologous end joining dna repair pathway (guo et al. ) . indeed, dna damage induction seems to be a common feature of many dna viruses including adenoviruses, herpesviruses, polyomaviruses, and papillomaviruses (luftig ) . most viruses degrade ddr components, but ddr activation and recruitment of some of its components into viral replication centers is also common. however, the outcomes of virus-host interactions at the ddr level are still poorly understood, and it 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double-stranded form by purified escherichia coli proteins we thank silvia torres and pablo herná ndez for technical assistance. this work was supported by grants from the spanish mineco (bfu - ) and the european research council (erc- -stg- -virmut) to r.s., and by a ph.d. fellowship from the spanish ministerio de educació n to m.p.-g. data are available on request.conflict of interest: none declared. key: cord- -re jstvi authors: devitt, patrick title: can we expect an increased suicide rate due to covid- ? date: - - journal: irish journal of psychological medicine doi: . /ipm. . sha: doc_id: cord_uid: re jstvi human disasters come in all shapes and sizes including wars, terrorist violence, natural events, economic recessions and depressions as well as infection. as a species more fragile than we often allow, humans would be expected to adversely react to these types of disasters in terms of mental ill health and possibly suicidal behaviour leading to increased demands on the mental health services. this narrative historical paper examines relevant studies into how previous disasters affected mental health and suicidal behaviour. the characteristics of what is known of the current covid- disease are analysed and compared to other types of disasters with a view to gaining some insight into what we might expect. of all the types of disasters, economic recession appears most toxic. mitigating the worst effects of recession appears to be protective. particularly vulnerable groups are identified in whom we might expect an increase in suicidal behaviour. human disasters come in all shapes and sizes including wars, terrorist violence, natural events, economic recessions and depressions as well as infection. ireland has experienced its own share of these types of disasters including in the last century our war of independence, the civil war, 'the troubles' in northern ireland and the to economic meltdown. our temperate climate and geographical location have largely saved us from natural disasters such as earthquakes, hurricanes and widespread flooding. as a species more fragile than we often allow, humans would be expected to adversely react to these types of disasters in terms of mental ill health and possibly suicidal behaviour leading to increased demands on the mental health services. this paper will examine relevant studies into how previous disasters affected mental health and suicidal behaviour. the characteristics of what is known of the current covid- disease will be analysed and compared to other types of disasters with a view to gaining some insight into what we might expect. what provokes an individual to engage in an act of suicide on any given date and time is not straightforward. it is likely that such a decision and act comprises 'a perfect storm' which includes the presence of mental illness, perhaps a genetic pre-disposition, family history, certain personality traits (such as impulsivity), the availability of means, the abuse of alcohol or other substances and a recent insoluble predicament (pridmore, ) . in population terms, certain associations are well known including mental illness, substance abuse, availability of the means of suicide as well as social and cultural factors. emile durkheim, around the end of the th century, offered the first comprehensive theory of suicide (durkheim, ) . he linked the apparent rise in suicide rates at the time to modernity and the associated weakening of family and community bonds. it was durkheim's view that linking suicide almost exclusively with mental illness was hopelessly inadequate and completely ignored potent social forces. durkheim described four types of suicide, two on each of two axes. too much social integration resulted in the altruistic suicide and not enough, the egotistic suicide. in terms of regulation of society, too much control resulted in fatalistic suicide and insufficient control led to anomic suicide due to alienation from society. it was durkheim's view that suicide was reduced during wars because of the greater social integration. it is now generally accepted that the presence of mental illness is a major factor but not the exclusive factor in the incidence of suicide. world war ii durkheim's view that war reduces suicide through greater social and political integration was examined in the united states between and . it was concluded, 'an examination of trends and suicide rates among white us adults does not show, however, that war directly decreases the suicide rate : : : ' (marshall, ) . though all-age male and female suicide rates decreased in scotland during world war ii, taking account of the prior background declining trend (in , . / , ; in , . / , ), it was concluded that the rate of suicide was higher than it would otherwise have been. the figures concealed large increases in the suicide rate in young men and an increase of suicide by firearms (henderson et al. ) . 'the troubles' in northern ireland up to the signing of the belfast or good friday agreement in were associated with a suicide rate half of that after that date, from about deaths per year (approx. / , population) in the mid- s to more than deaths (approx. / , ) by the year . this was thought to be related to the 'growing of the social economic and political legacy of the troubles and in particular of the transgenerational effect of conflict-related trauma on the mental health of the population : : : ' (o' connor & o'neill, ) . it was argued that high suicide rates in some areas might have been because of the loss of community connectedness and sense of purpose that was evident during the troubles in addition to the coexistence of many traditional risk factors as well as conflict exposure (o'connor & o'neill, ) . the turning inwards of aggression in depression can lead to suicide, and when turned outwards, the suicide rate decreases. this was suggested as a possible cause of the relative lack of psychiatric morbidity and suicide during the troubles (curran, ) . studies of the effects of these attacks have reached quite variable conclusions. the decrease in british suicide rates noted the month after the attacks was thought to be a demonstration of durkheimian social principles (salib, ) . however, in the netherlands in the months following / , fatal and non-fatal suicidal behaviour rates rose (de lange & neeleman, ) . in new york, a temporary drop was noted along with a temporary rise in other locations and an overall reasonably constant suicide rate in the united states (claasen et al. ). in germany, no evidence of an increase in suicide rate was found. 'there was no evidence of durkheim's theory attributable to the / attacks was found in the sample : : : ' (medenwald, ) . in the days following the th july attack and also on the days following st july second wave, brief but significant reductions in suicides were seen that had not been seen during the same period in the previous years. no evidence was found of any longer-term effect on suicide (salib & cortina-borja, ). as shown in table , the evidence for the effect of war and violence on suicide rate is quite mixed. the increased rate in young men seen in scotland during world war ii appears most persuasive. a comparison of the prevalence and characteristics of suicide following the january queensland australia floods to the years prior for the same period found no increase in suicide rates during the months after the floods. however, a delayed effect was not discounted and ongoing surveillance was recommended. in a personal communication to the author, it appeared there was no significant increase in suicide following the earthquake in new zealand on february (de leo et al. ). significant increases in the prevalence of suicidal ideation and suicide plans months after hurricane katrina (august ) compared to years later were noted (kessler et al. ) . in puerto rico, from an average of suicides per month ( / , ) in the months before hurricane maria in the rate rose to per month ( / , ) in the immediate months afterwards (preliminary statistics of cases of suicide in puerto rico, ). severe acute respiratory syndrome the severe acute respiratory syndrome (sars; coronavirus- ) in did not give rise to a pandemic but was responsible for a number of epidemics notably in hong kong. a study of the longer-term morbidity in a sars survivor cohort concluded that the outbreak should be regarded as a mental health catastrophe (mak et al. ). other studies showed a spike in the suicide rate especially among persons age and over in hong kong in , a . % increase from (yip et al. ; cheung et al. ). in a further study, the suicide motives among sarsrelated suicide deaths were found to be associated with stress over a fear of being a burden to their families during the negative impact of the epidemic. social engagement, mental stress and anxiety at the time of the sars epidemic among a certain group of older adults resulted in exceptionally high rate of suicide deaths (yip et al. ) . little direct data on any psychiatric surge is available from the pandemic. however, by computing monthly suicide and mortality rates and matching with exogenous social and political events, an estimate of the impact of these events on suicide behaviour in the united states between and concluded: world war i did not influence suicides; the great influenza epidemic caused it to increase; and the continuing decline in alcohol consumption between and depressed national suicide rate (wasserman, ) . analysis of the psychiatric aspects of a future avian flu pandemic concluded that such a pandemic would result in an increase in required psychiatric services with a huge increase in hospital admission, increased mortality as well as increase in delirium symptoms due to high fever. no comment was made on the effect on the suicide rate (rissmiller, ) . the great depression ( ) ( ) ( ) ( ) ( ) this economic depression began on tuesday, october , with the famous stock market crash and lasted until spreading from the united states to most other developed economies. between and , a . % increase in suicides was reported in the united states, the largest increase in any -year period from to (luo et al. ) . in , during this economic crisis, suicide rates soared - % in japan, % in hong kong and % in south korea. taiwan and singapore which were not as severely affected showed no link between suicide rates and economic difficulties (chang et al. ). impact of the economic recession and subsequent austerity on suicide and self-harm in ireland, ireland, to one study found that by the end of the suicide rate for males was % higher than if the pre-recession trend continued but almost unchanged for females (corcoran et al. ) . male and female self-harm rates were % higher. it was concluded that 'five years of economic recession and austerity in ireland have had a significant negative impact on rates of suicide in men and on self-harm in both sexes : : : ' (corcoran et al. ) . a study linking unemployment and mortality in european union countries found that finland and sweden were outliers in that increases in suicide did not parallel unemployment. the authors speculated that active supportive labour-market programmes were partly responsible (stuckler et al. ). can we expect an increased suicide rate due to covid- ? covid- has hit the world including ireland in a shockingly abrupt manner. an exponential increase in cases has necessitated draconian government measures to slow the spread of the virus and mitigate its effects with respect to the availability of healthcare services. a raft of 'stay-at-home' and similar demands has plunged the economy into recession. how are people reacting to this rapid and profound change in their lives? some were in denial until virtual 'lockdown' was imposed. others are wracked with anxiety, especially the elderly with respect to contracting the virus and ending up in an icu bed. many have lost jobs and perhaps livelihoods. many are working from home along with spouses and children. increase in domestic violence has been reported (mcgee, ). anecdotal reports suggest that people are drinking more and are advised to guard against addiction (irish times, ). it is uncertain how long these restrictions will last. as yet, there is no measurable or observable effect on mental health services as it is likely that individuals suffering from anxiety will steer clear of general practitioners who are overwhelmed with dealing with the effects of the virus. people are also reluctant to attend emergency departments. the impact on healthcare workers will be particularly profound. working long hours, risking contracting the virus themselves and witnessing the overwhelming of the icu services will likely extract a psychological toll. further, doctors and nurses will be exposed to the risk of 'moral injury' with respect to decisions to deprive some individuals of care they otherwise would have provided. is the current pandemic akin to a war, natural disaster or other epidemics? is the economic recession we are experiencing and will experience in the future akin to the - recession? as overused is the war metaphor, similarities do exist in terms of the long and uncertain timeline, the frequent strategy and mortality bulletins, economic impact and emergency, previously unthinkable, legislation as well as sending our soldiers (healthcare workers) to the front. natural disasters are usually acute in onset and duration but health and disease after-effects resemble aspects of this pandemic. as appears obvious, this pandemic is probably closest to previous epidemics and second only in modern times to the 'spanish flu' and in medieval times to plague. applying durkheim's social integration explanation for the apparent reduction in suicides during war, it does appear that there is a widespread sense of solidarity, in particular with respect to social distancing and a sense of tolerating these restrictions for the collective good. on that basis, we might expect a decrease in suicides while the emergency persists. however, the hong kong sars experience alerts us to the possibility of an increase in the suicide rate of the elderly (already recognised as a vulnerable group in terms of suicide) who are disproportionately affected with respect to 'cocooning', severity of illness and mortality. the elderly cannot be unaffected by certain musings in the united states and the united kingdom regarding their expendability so as not to injure the economy. from an economic perspective, the financial protections provided by the government will mitigate the expected ill effects of sudden poverty. however, these measures are temporary and it is likely that recession will continue for some time though, as most commentators believe, not as long as the - recession. in addition, it may be a different type of recession in that it has been externally imposed and 'not our own fault' as had been the common wisdom during the previous recession -'we all partied'. is it likely that people and social groups are more able to tolerate hardships that are externally imposed such as some wars and natural disasters? perhaps. similar to the northern ireland and hong kong studies discussed above, when this crisis has passed, it may well be that we will see an increase with respect to the development of mental illnesses such as anxiety and post traumatic stress disorder, with some associated increase in suicidal behaviour. humans are always prone to disasters which, in general, have an adverse effect on their mental health. of all the types of disasterswar, violence, natural disasters, epidemics/pandemics and economic recessionit appears that the most toxic is that of economic recession. mitigating the worst effects of a recession appears to be protective. the current financial protection measures in this regard should continue. when the dust has settled, we may not see a major increase in pre-existing suicide-rate patterns. however, previous experience suggests that we may well see an increase in psychiatric presentations and short-term spikes in suicidal behaviour. particularly vulnerable groups include healthcare workers, the elderly and those who suffer crushing economic adversity. consideration should be given to prioritising these groups for ongoing mental health surveillance and treatment if necessary. the author asserts that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committee on human experimentation with the helsinki declaration of , as revised in . the author asserts that ethical approval was not required for publication of this paper. this article received no specific grant from any funding agency, commercial or not-for-profit sectors. was the economic crisis responsible for rising suicide rates in east/southeast asia? a time-trend analysis for japan a revisit on older adults' suicides and severe acute respiratory syndrome (sars) epidemic in hong kong terrorist attacks in the usa on suicide in areas surrounding the crash sites impact of the economic recession and subsequent austerity on suicide and self-harm in ireland: an interrupted time series and analysis psychiatric aspects of terrorist violence: northern ireland - has the suicide rate risen with the queensland floods? the effect of the september terrorist attacks on suicide and deliberate self-harm: a time trend study suicide: a study in sociology changes in scottish suicide rates during the second world war trends in mental illness and suicidality after hurricane katrina impact of business cycles on us suicide rates political integration and the effects of war on suicide: united states gardaí report rise in domestic violence cases the terror attacks of / and suicides in germany long-term psychiatric morbidities among sars survivors mental health and suicide risk in northern ireland: a legacy of the troubles? it is vital now that we think before we drink preliminary statistics of cases of suicide in puerto suicide and predicament: life is a predicament psychiatric aspects of the impending avian flu pandemic on suicide and homicide in england and wales terrorist attacks in london on suicide in england the public-health effect of economic crises and alternative policy responses in europe: an empirical analysis the impact of epidemic, war, prohibition and media on suicide: united states the impact of epidemic outbreak, the case of severe acute respiratory syndrome (sars) and suicide among older adults in hong kong social and economic burden of suicide in hong kong sar the author has no conflict of interest to disclose. key: cord- - dhldjjp authors: sarraf, david; sarraf, danielle rachel; sadda, srinivas title: is virtual existence our new reality? date: - - journal: graefes arch clin exp ophthalmol doi: . /s - - - sha: doc_id: cord_uid: dhldjjp nan the covid- crisis knows no boundaries, and this tragic pandemic has put everyone, rich and poor and obscure and famous, on red alert. eye specialists for the most part have been away from the front lines; however, it is interesting that the first documented encounter of infected coronavirus patients was by a heroic ophthalmologist in wuhan who tragically succumbed to this disease [ ] . in addition, a number of brave ophthalmologists have volunteered to wage battle in ravaged emergency rooms (er) and intensive care units (icu) around the world. these courageous souls represent the best of our community during very difficult circumstances, and we are very proud of their contributions. there are many other stories of heroism that have come to light especially among those on the front lines during these tough times, and deservedly, these efforts have garnered a great deal of attention and media headlines. but it is surprising that there has been a dearth of discussion and discourse in the media regarding the trending attitudes and cultures of our society that are ever more apparent during a pandemic crisis. a culture that more and more is moving in the direction of a virtual existence with a preference to limit human contact and only communicate through a digital interface that eliminates our deepest anxieties and fears. it is clear that we have encountered a new enemy. fascist dictators with reckless tendencies or religious fanaticisms or genocidal obsessions have been replaced by a biologic killer. our soldiers no longer wear military uniforms but instead they don surgical scrubs and white coats. our politicians no longer send young healthy men to an uncertain destiny in killing fields. thankfully, our leaders now prioritize the life of our citizens even the weak and infirmed who may already be at death's door. for this, we should be grateful that we live in a world where we are all dedicated to peace and the sanctity of life. the parallels with war time tragedies are inescapable. in fact, recently a local health official [ ] quoted the great winston churchill, who charismatically guided the uk and the allied nations through the second world war to eventual victory. in an effort to urge greater resiliency of her constituency in the fight against the coronavirus which continues to infect thousands of people every day, just here in the state of california, she noted: "…this is not the end. it is not even the beginning of the end. but it is, perhaps, the end of the beginning." but we are drawn to another famous quote by a contemporary of churchill, franklin d. roosevelt: "we have nothing to fear but fear itself." the political policies to fight covid- and "flatten the curve" of infection have been successful and have reduced conversion rates so that hospital ers and icus are not overburdened, ensuring that patients with coronavirus throughout the world receive optimal care. it is clear that one of the reasons for the higher death rate in italy may relate to severely ill covid patients who did not receive necessary supportive care in time because hospitals were overwhelmed by deathly sick coronavirus patients. here in california, social isolation policies have thus far been very successful, and the curve has been presumably flattened. hospitals and icus across the state are operating under capacity, and all patients have been receiving the supportive care that they need [ ] . yet, is there an end in sight? new coronavirus infections are continuing at an unrelenting pace. here in california, the daily rate of new infections has steadily risen at approximately to cases per day, and mortality has continued at approximately to deaths or more per day for the last several weeks, despite increasingly warm temperatures [ ] . does it make sense therefore to continue to isolate communities when our hospitals are operating comfortably and infection rates are not abating? what is the cost of this policy? this is an ethically, complicated question, as there is no ideal or perfect solution. morbidity and mortality from covid- are a terrible tragedy but they are relatively easy to track. the long-term consequences of current policy in terms of mental health and societal decay are much more difficult to quantify. nevertheless, it is clear that the toll of social isolation has been heavy. so far, almost million jobs have been lost, the unemployment rate has ballooned to %, and million citizens in the usa alone have filed for unemployment insurance from the government which will have to doll out hundreds of millions, if not billions, of dollars as compensation [ , ] . as president trump has stated, we now have the worst unemployment rate since the great depression [ , ] . hundreds and thousands of businesses, especially small businesses, are at risk of collapse as they dip into their limited reserves to pay employees shuttered at home and attempt to cover overhead without any stream of cash flow for the last several months. the growing societal problem of the homeless, already a major issue in urban cities like san francisco and los angeles, is accelerating, and this may establish a nidus for an even greater risk of infection from covid and other insipid diseases. mental health has suffered as masses of people sit idle at home unable to work and provide for their families and frustrated at the loss of their civil liberties and privileges such as playing in the park or walking on the beach. in fact, % of us adults concede that their mental health has deteriorated due to the covid- pandemic and the shelterin-place orders, and calls and texts to crisis lines have dramatically increased [ ] . depression, suicide, and domestic violence are becoming pervasive problems in many of our struggling communities during this crisis [ ] . is it time to stop running and hiding? as fdr stated so long ago, is fear our greatest enemy? are we climbing a slippery slope of a virtual existence where we will no longer condone human contact and interaction? will we forever communicate on line through webcasts and zoom sessions forsaking all face to face exchange? it is clear that covid is not going away anytime soon. the risk of infection may continue throughout the coming months and even into next year. until the advent of herd immunity or a vaccine, which both seem many months away, we cannot evade this invisible enemy. perhaps, the focus of our policies should be more targeted and aimed toward protecting and isolating the elderly and the infirmed and those with comorbid conditions until a vaccine or effective antiviral treatment is available. continued implementation of social distancing policies and reduction of transmission through improved community hygiene is essential while gradually restarting the economy and reintroducing civil liberties so that one crisis will not be replaced by another. it is clear that we are a social people by nature. but this way of life is being eroded away by the digital revolution and by our fears of human contact. already millennials and centennials seem to communicate more and more on a digital interface and eschew face to face exchange. the current crisis and our raised fears and anxieties of infection threaten to drive an even greater wedge through human connection. communication through a screen or digital interface to allay our ever-growing unease with human contact sadly may become our predominate means of interaction. certainly, this is not the direction we want to go. we stand to lose so much through these forms of aseptic communication that lack vibrancy and engagement and are void of dynamic interchange and instruction. virtual reality will lead to a world devoid of soul and emotion and human spirit, a sterile and lifeless way of life in which the many benefits of face to face engagement will be completely lost. we need to overcome our fears and reach out and touch the awesome world that we live in and understand that we cannot hide at home behind our computers forever in a virtual reality devoid of human intimacy and vibrant exchange. li wenliang, a face to the frontline healthcare worker. the first doctor to notify the emergence of the sars-cov- , (covid- ), outbreak a ( ) county reports more coronavirus deaths, a new single-day high covid- ( ) california department of public health an unemployment rate of %? the real jobless picture is coming together real unemployment rate soars past %-and the u.s. has now lost . million jobs the implications of covid- for mental health and substance abuse a new covid- crisis: domestic abuse rises worldwide publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. key: cord- -k rs dql authors: doerre, a.; doblhammer, g. title: age- and sex-specific modelling of the covid- epidemic date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: k rs dql background: recent research points towards age- and sex-specific transmission of covid- infections and their outcomes. the effect of sex, however, has been overlooked in past modelling approaches of covid- infections. aim: the aim of our study is to develop an age- and sex-specific model of covid- transmission and to explore how contact changes effect covid- infection and death rates. method: we consider a compartment model to establish forecasts of the covid- epidemic, in which the compartments are subdivided into different age groups and genders. estimated contact patterns, based on other studies, are incorporated to account for age- and sex-specific social behaviour. the model is fitted to real data and used for assessing hypothetical scenarios with regard to lockdown measures. results: under current mitigation measures as of mid-august, active covid- cases will double by the end of october . infection rates will be highest among the young and working ages, but will also rise among the old. sex ratios reveal higher infection risks among women than men at working ages; the opposite holds true at old age. death rates in all age groups are twice as high among men as women. small changes in contact rates at working and young ages may have a considerable effect on infections and mortality at old age, with elderly men being always at higher risk of infection and mortality. discussion: our results underline the high importance of the non-pharmaceutical mitigation measures in the current phase of the pandemic to prevent that an increase in contact rates leads to higher mortality among the elderly. gender differences in contact rates, in addition to biological mechanisms related to the immune system, may contribute to sex-specific infection rates and their mortality outcome. to further explore possible pathways, more data on covid- transmission is needed which includes socio-demographic information. right from the start of the covid- pandemic, the importance of age on covid- contraction and fatality has been recognised (among others, esteve et al. ( ) , dudel et al. ( ) , kulu and dorey ( ) , wu and mcgoogan ( ) , karagiannidis et al. ( ) ), as well as of coresidence patterns (esteve et al. ( ) ). compartment and agent-based models aiming at projecting the spread of the disease have incorporated age as an important variable of transmission (e.g. davies et al. ( ) , deforche ( ) , colombo et al. ( ) , blyuss and kyrychko ( ) , balabdaoui and mohr ( ) ), in addition to other characteristics such as space (colombo et al. ( ) ) or contact patterns ). an important determinant, which appeared to be largely overlooked in modelling exercises, is sex. in the following, we will refer to sex when discussing technical details and biological factors, and gender, when referring to social factors. while studies generally notice that infection and in particular fatality rates were higher among elderly men than women, the reverse appears to be true for infections at working ages (sobotka et al. ( ) ). in germany, during the first wave of the pandemic through mid-may, infection rates were higher among women than men at working ages (figure ), while they were higher for men thereafter. one reason for this difference, in addition to biological factors (see discussion below) may lie in genderspecific contact rates. estimates of contact rates (van de kassteele et al. ( ) ) based on the polymod study (mossong et al. ( ) ) showed that household, workplace and school structures strongly shape ageand gender-specific contacts made by individuals. using the contact matrices from the latter study and calculating the ratio of the age-specific number of contacts for men and women (contacts men/contacts women) a clear pattern emerges (figure ): among ages - , contacts are between %- % higher among women, while among ages to , they are %- % higher among men. at the highest ages, the pattern reverses again, with women having slightly more contacts. the aim of our study is to model covid- transmission taking into account the two crucial demographic factors age and sex. we develop an seird-model that incorporates age-and sex-specific contacts, which shape transmission rates. the model may be used for short-and long-term projections, our example explores short-term effects up to two and a half months of hypothetical changes in contact rates. the model can be used to develop scenarios which address the effects of age-and gender-specific changes in contacts due to the closing of schools, kindergarten and shops, or work in home office, as well as to explore the effect lifting of these measures. while we are not able to address these effects separately, we translate them into hypothetical changes in age-and sex-specific contact rates by developing three scenarios. the first scenario reflects a continuation of the situation of mid-august ; the second assumes a lifting of measures mainly at working ages, and the third extends this to children, adolescents, and young adults. the manuscript is structured as follows: first we introduce the basic seird model and discuss how ageand sex-specific contact modelling was incorporated. we present the numerical implementation of the model, model fitting and the development of uncertainty intervals. then we introduce our scenarios and present the projection results in terms of number of active infections (prevalence), and cumulated number of deaths by october . we also explore how increasing contacts affect sex-ratios in infections and deaths. we close with a discussion of the results, the strengths and limitations of our model, as well as policy implications. figure : seird compartment model with transitions. (s → e: susceptible person becomes exposed to the virus, e → i: exposed person becomes infectious, e → r: exposed person is removed due to recovery, i → r: infectious person is removed due to recovery, i → d: infectious person is removed due to death) the core of the epidemiological model is an seird compartment model (see hethcote ( ) ) consisting of the epidemiological states s (susceptible, i.e. not yet exposed to the virus), e (exposed, but not infectious), i (infectious), r (recovered), and d (dead). the compartments represent individual states with respect to contagious diseases, i.e. covid- in this case, and the transitions between them are considered on a population level (see figure ). in this sense, the compartment model is used to describe a population process, but is not intended to model individual processes with respect to covid- . the following essential rate and fraction parameters are involved in the model: β (contact rate): the average number of individual contacts per specified timespan that are potentially sufficient to transmit the virus (see below for detailed specification) ρ (manifestation index, fraction): the fraction of people who become infectious at some time after being exposed to the virus (incubation rate): the mean rate of exposed people to become infectious; / is the average incubation time γ (recovery rate): the mean rate of exiting the infectious state, either to recovery or death; /γ is the average duration of the disease τ (infection fatality rate): the fraction of people who die due to covid- the contact model is considered for a population of n individuals, which is decomposed into a disjoint groups. for each group a = , ..., a, the proportion of individuals with regard to the whole population is n a /n , where n a denotes the number of individuals in group a. for any a ∈ { , .., a} and b ∈ { , ..., a}, let λ ab be the average number of contacts of an arbitrary individual from group a with individuals in group b during a fixed base time unit δ, e.g. hours. more specifically, define η ab (t , t ) as the random number of contacts of an individual in group a with any individual from group b over the timespan [t , t ] and η a * (t , t ) := a b= η ab (t , t ) as the (random) overall number of contacts of an individual from group a. it is assumed that η ab (t , t ) is poisson distributed as η ab (t , t ) ∼ poi t t µ ab (s) ds via the contact intensity µ ab (t). by assuming independence of contacts to different groups, it follows that η a * (t , t ) is also poisson distributed having intensity µ a * (t) = a b= µ ab (t). the average rate of contact of any individual from group a with group b is then obtained as where for the sake of simplicity we assume that µ ab (t) is periodic in the sense that µ ab (t + δ) = µ ab (t) for all t . deviations from these assumptions can be incorporated by appropriate modifications to the contact model and parameter set. in the compartment modeling approach, individuals within each group are generally assumed to be homogenous with respect to contact behaviour and no individual effects are considered. in order to address the potential impact of the implementation and easing of lockdown measures, we expand the model structure to group-specific compartments. below, we define groups according to sex and age group, but the following reasoning is valid for any specification of disjoint groups, given that the resulting groups are sufficiently large. specifically, for given groups a = , ..., a and any time t, set s a (t) as the number of susceptible people in group a at time t, e a (t) as the number of exposed people in group . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint a at time t, and so on. the group-specific compartment model is characterised by the ode system for all groups a = , ..., a, which is a direct extension of the ode system of the basic compartment model for the special case a = . we define as the effective contact rate between groups a and b, where w is the secondary attack rate, m ab is the specific mitigation effect by lockdown measures with regard to contacts between groups a and b, r is a general factor that accounts for compliance to distance, isolation and quarantine orders, h b is the proportion of infectious people in group b in need of hospitalisation and λ ab is the basic contact rate between groups a and b when no lockdown measures are in place. as we are primarily interested in shortterm prediction, we do not model biological aging, i.e. transitions between demographic groups. therefore, for any time t, compartment-specific additivity is assumed, i.e. the system is closed, meaning that the sum of all odes is at each time t. in the absence of any lockdown measures, the general contact patterns are characterised by the basic contact rates λ ab , which represent how intensive/often group a has any contact with group b sufficient for potential virus transmission. in the polymod study (mossong et al. ( ) , , participants from countries including germany reported the number and extent of their social contacts during a randomly assigned hour period, using a written diary. the age and gender of the contacted persons were recorded, among other information. overall, the study contains information on , contacts, distributed across the participating countries. the overall contact pattern for germany is displayed in figure . the behaviour of the epidemiological model is primarily governed by the effective contact rates β ab which result from the basic contact rates λ ab by accounting for the secondary attack rate and lockdown measures. it is implicitly assumed here that hospitalised cases are effectively isolated from the remaining population and can not spread the disease. note that the product ( − m ab )( − r)( − h b ) represents the proportion of potential virus transmissions that are not prevented. based on the compartment model, derivative states such as the demand for hospitalisation and demand for intensive care units can be modeled separately by imposing estimated proportions on the compartment i. more precisely, h a (t) and c a (t), i.e. the number of hospitalised persons and patients in intensive care in group a at time t are calculated as: where h a is the age-specific proportion of infectious people in need of hospitalisation and c a is the agespecific proportion of hospitalised cases that need intensive care. for these parameters, estimates are available from imperial college covid- response team ( ) and verity et al. ( ) ; see table . . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . we have implemented the suggested model in r using a discrete approximation of the ode system via the forward euler method (see butcher ( )). the step size ∆t is chosen as a quarter fraction of one day. accordingly, the transition rates between the compartments need to be adjusted, whereas the fraction parameters remain unchanged. for instance, if the average incubation time is days and ∆t = / (days), the transition parameter = / · / = / , whereas the manifestation index ρ, as the relative proportion of exposed people developing symptoms, is the same for any ∆t. the time-discrete . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint approximation of the system of odes is therefore described as follows. we suggest to fit the model along the following consecutive steps: ( ) determine a timespan { , ..., t } during which no lockdown measures had been in place, and determine the cumulative number of infections during this time. ( ) based on plausible ranges for the involved compartment parameters and the initial state of the compartment model, fit the contact intensity model with regard to the cumulative number of infections during { , ..., t }. in order to derive the secondary attack rate w from the contact rates λ ab given in van de kassteele et al. ( ), we fit the proposed compartment model to the reported cases during a timespan { , ..., t } of no lockdown. this step is necessary, because the social contact rates λ ab do not incorporate the specific transmission characteristics of sars-cov- , such as the average length of the infectious period and average infection probability per contact. we assume that w is not specific to age or sex. we employ as a least-squares criterion function in order to determine the optimal value w := argmin w> q(w), where i cum are the observed cumulative infections, and i cum (t|w) are the estimated cumulative infections based on the epidemiological model given w. hence, w is the scalar parameter for which the cumulative infections are best predicted retrospectively. note that the observed cumulative number of infections is usually recorded for each day, while the step size ∆t in the model may be different. thus, appropriate matching of observed and estimated values is necessary. this fitting method requires that the number of infections for the geographical region considered is sufficiently large, such that the mechanics of the compartment model are plausible. note that potential under-ascertainment may not substantially change the optimal value of w as long as the proportion of detected cases does not strongly vary over time. furthermore, the suggested fitting method is based on the assumption that the probability of virus transmission is independent of age and sex, given that a contact has occurred. if different propensities of virus transmission are allowed for, the contact matrix may be correspondingly adjusted along introduced parameters w , ..., w ab for each group combination or w , ..., w a , if the probability of transmission only depends on the contact group. the criterion function is likewise extended as (w , ..., w ab ) → q(w , ..., w ab ). however, optimisation in this extended model requires a sufficiently large number of transmissions and detailed information on the recorded infections, and may lead to unpractically vague estimates otherwise. therefore, we suggest to employ the simpler model with univariate w first. in order to account for parameter uncertainty, we develop uncertainty intervals for the number of people in each compartment. as a cautionary remark, note that these intervals are not to be equated to confidence intervals in the classical sense. though the resulting intervals are conceptually comparable to bayesian credibility intervals, they are to be distinguished in that no prior distribution is explicitly assumed here. note that these intervals do not reflect uncertainty in terms of the underlying infection data. we predict the number of cases in each age-specific compartment using a monte carlo simulation method. for each simulated run, all parameters are independently drawn from their respective range, yielding . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . an instance of a hypothetical parameter setup. given these parameters, the seird ode model is approximated using the forward euler method and known initial states, as described above. after n r of such simulated runs, the prediction intervals for all relevant values are construed based on the pseudo-empirical trajectories of the compartment model. furthermore, prediction intervals are derived as point-wise quantile ranges for each t. for instance, an % prediction interval for the number of infectious people in group a at time t is [i a, % (t), i a, % (t)]. first, we fitted the model to observed covid- infections using transition rates from literature as described under section for the period february to march . we estimated the model parameter w, also termed secondary attack rate, which reflects the probability of infection per contact, by least squares between observed and predicted values, as described in section . . second, we developed three scenarios starting our projections on august and, using quarter-days as base time, ending on october . the first scenario, which is our baseline scenario, assumed that the age-and sexspecific contacts are down by %, i.e. only % of the contacts estimated by van de kassteele et al. ( ) were realized between start and end of the projection. this applied to all age groups and to both sexes. this scenario should reflect continuous distancing measures as were present in mid-august. the second scenario assumed that contacts at working ages - were increased by percentage points (pp), and among those aged - by pp, equaling a decline of % and % respectively. all other ages remained at % contact reduction. this should reflect the return from home office settings, the opening of shops, cafes, restaurants, etc. the third scenario considers an additional increase in contact rates among ages - by pp, which should reflect the opening of schools and venues mainly visited by young individuals. we explored the following age-specific outcomes: fitting our model to covid- infections observed during our fitting period ( feb - march ) results in an estimate of the secondary attack rate w ≈ %. we started with , active infections on august and under scenario this figure increased to approximately , ( figure ) (men: , ; women: , ). the number of active infections was highest at age - (men: , ; women: , ), followed by age - (men: , ; women: , ), and age - (men: , ; women: , ). the cumulative number of deaths increased from , to , with , men and , women. by october , infection rates (table ) were highest among the - -year old (men . and women . per individuals) followed by ages to ( . - . ), and ages - ( . - . ). at ages above , infection rates declined rapidly, almost halving from individuals in their fifties ( . - . ) to those in their sixties ( . - . ), while at older ages the decline followed at a much lower pace (ages - : . - . ; ages +: . - . ). sex ratios of infections were below in the age interval to , indicating a higher risk of infections among women. from age onwards they were generally above , thus turning the disadvantage towards men. as expected, death rates (table ) increased with age with a decline at the oldest ages probably reflecting health selection or better protection of the oldest old. they were more than twice as high among men than women, again with the exception of the oldest age group, where men might be positively selected by health. scenario assumed increased contacts at working ages and arrived at , active infections by october and therefore , active infections more than in scenario (men , ; women , ). these additional infections stemmed from all ages, even if the risk of infections increased most among the working ages. sex ratios of infection rates remained . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . unchanged, because we increased contact rates at the same proportion for both genders. the additional infections translated into an additional deaths (men: ; women ); among women, three quarters of these deaths resulted at ages and above; among men, %, reflecting their higher mortality already at younger ages. sex ratios of death rates remained unchanged as compared to scenario , reflecting our model assumption of parallel increase in contact rates for both genders. scenario with increased contacts at young and working ages resulted in , active infections and thus , more than in scenario (men , ; women , ) which translated into an additional deaths with the majority resulting from ages and above (women %; men %). there was little change in sex ratios as compared to the other two scenarios. incorporating age-and sex-specific contact rates in a covid- compartment model permits exploration of the effects of changes in mitigation measures on the two genders. we developed three scenarios which assumed ongoing distancing measures versus easing of contact restrictions in working ages, and among adolescents and young adults. our projections do not set out to forecast the actual number of covid- infections in a time span of about two months, they rather assess the effect of increased contacts on the infection and mortality risks of the two genders and the various age groups. the fit of our model to the baseline period in february and march results in an estimated secondary attack rate w ≈ %, putting our findings in close agreement with the rates reported in ghangdou, where the household w varied between % and %, and the non-household w between % and % (jing et al. ( ) ), although higher attack rates of up to % have been reported e.g. for meals and holiday visits (liu et al. ( b) ). three important lessons can be learned from our scenarios. first, even a small change in contact rates has a large impact on infections and deaths. in our projections we assumed an increase ranging from to pp. this reflects the fact that without non-pharmaceutical mitigation measures (npmm) such as masks, physical distance between individuals, better air ventilation and hygiene, and without contact tracing, the infection rates would return to the initial exponential increase. this was reflected in a reproduction rate of . to . , as observed at the beginning of the pandemic (lin et al. ( ) , and alimohamadi et al. ( ) , rki ( )). however, the presence of npmm also mitigates the effect of the increase in contacts due to the return to office, opening of shops, restaurants, as well as schools, and venues visited by young adults, leaving it far from the initial impact. in our present scenarios, both effects, the change of contact rates and the change of their impact, are captured in the reduction matrix (m ab ), which is multiplied with the matrix of the contact rates. one alternative approach would be to develop separate scenarios for changes in the secondary attack rate w due to npmm and changes in the contact rates (m ab ), which is one possibility to modify this analysis further. at any rate, our scenarios show that small changes already have large impacts on infections and deaths. this implies that the impact of contacts must be diminished considerably to allow increases in contacts without returning to exponential growth of infections, hence underlining the high importance of the npmm in the current phase of the pandemic. second, due to intergenerational contacts, any easing of measures in working and young ages will inevitably lead to an increase in infections and deaths, the latter mainly at old ages. over all ages, deaths will increase by % when contacts increase at working ages, and increase by % when contacts also rise among the young. the vast majority of these increases occur at old ages, with % among women and % among men, whereby the fatality among men is more than twice as high as among women. thus, elderly men are at a particular risk of death due to increased contacts. however, our model assumptions are based on fatality rates at the beginning of the pandemic, which may have changed because of better treatment options of critically severe covid- cases using, e.g., dexamethasone (cain and cidlowski ( ) ). thus, we might overestimate mortality under current knowledge and treatment options. still, increases in contacts need to be accompanied by special measures protecting the elderly from death, without negative physical and mental health consequences due to quarantine and isolation measures (galea et al. ( ) ). contrary to deaths, infections will mainly increase at young and middle ages with a lower risk of severe covid- symptoms or even asymptotic disease courses. third, small changes in contact rates will not change the sex ratios in infections and deaths. at all ages, men will have more than twice the mortality risk from covid- , while the risk of infections is more frequent among working age women than men. at old ages, men have a higher infection risk. note that, in absolute numbers, more women are diagnosed with covid- at old age due to their higher life expectancy. here a more substantial question arises, namely whether covid- infection rates are indeed gender-specific. german covid- infection rates, as in any other country, are biased by the . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . time-lag of reporting and by differential availability of pcr-tests over time and to subgroups of the population (rki ( )). gender-specific diagnoses in favour of women may reflect that higher contact intensities of women may have led to a higher rate of pcr tests and therefore to a smaller number of undiagnosed cases. in addition, women are more health-conscious than men (oksuzyan et al. ( ) ) and may have sought pcr testing to a higher degree even when presenting with weaker symptoms. on the other hand, takahashi et al. ( ) found sex-specific differences in immune response to covid- infections. for a further discussion of potential sex-specific mechanisms modulating the course of disease, see also (gebhard et al. ( ) ). thus, we can conclude that both biological and social factors contribute to sex-and gender-specific infection and mortality rates and that they are stable given small changes in contact rates. we focused on the practical emulation of the dynamic behaviour and process of the spreading of covid- while incorporating specific epidemiological information on the virus and disease. to achieve this aim we used a compartment modeling framework, which has become a standard approach in epidemiology due to its flexibility and accessibility. the main advantage of this modeling framework is that a considerable amount of demographic and epidemiological information can be incorporated while the essential model structure and implementation remain relatively simple. similarly, it is possible to extend the model to incorporate parameter uncertainty, as described above. furthermore, we want to emphasize the markovlike property of compartment modeling in the sense that current compartment sizes on a specific date are sufficient for deducing the subsequent behaviour of the epidemiological process, which makes the framework particularly attractive for forecasting and investigating hypothetical scenarios. however, there is one drawback to compartment modelling that it is inherently based on an averaging rationale which treats population groups homogenously and the average number of contacts in each group is a determining parameter. in contrast to truly stochastic models (such as agent-based models), no random or systematic individual deviations from the fundamental contact patterns are taken into consideration. in addition, geographical and spatial information are not explicitly considered in compartment modeling, and this further limits the scope of the forecasting results. in general, assessing the impact of introducing or easing different lockdown measures is remarkably difficult, especially because several aspects are usually changed simultaneously and the general behaviour of the population may change dynamically at the same time. some efforts have been made to address these issues in the literature, however we advise against using the proposed model for such purposes. one main reason is that the initial state for forecasting and fitting of the model relies primarily on available data sources, which are in the form of reported count data. in addition to the general limited validity of observational data, there is still insufficient knowledge on the specific characteristics of covid- and the actual current spread of the virus. naturally, other modeling approaches face the same issues of data quality. in our covid- forecasts, the number of infections and the number of deaths differ only slightly from models which do not differentiate by sex (data not shown). however, age-and sex-specific models provide better insight into the risk populations of infections and mortality. this helps to target health policy measures under scarce resources, such as who should be tested and vaccinated first. both biological sex and social gender appear to affect covid- infection rates and their outcomes; this needs to be acknowledged in health policy decisions and medical treatment. to further explore social factors on covid- transmission, more information that includes socio-demographic data is needed. . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . cc-by-nc-nd . international license it is made available under a perpetuity. is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . is the author/funder, who has granted medrxiv a license to display the preprint in (which was not certified by peer review) preprint the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint estimate of the basic reproduction number for covid- : a systematic review and meta-analysis age-stratified model of the covid- epidemic to analyze the impact of relaxing lockdown measures: nowcasting and forecasting for switzerland effects of latency and age structure on the dynamics and containment of covid- numerical methods for ordinary 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covid- epidemic in india age, gender and covid- infections sex differences in immune responses that underlie covid- disease outcomes estimates of the severity of covid- disease : a model-based analysis characteristics of and important lessons from the coronavirus disease (covid- ) outbreak in china, summary of a report of cases from the chinese center for disease control and prevention changes in contact patterns shape the dynamics of the covid- outbreak in china key: cord- -udokbcki authors: lilitsis, emmanouil; stamatopoulou, vaia; andrianakis, eleftherios; petraki, adamantia; antonogiannaki, elvira-markela; georgopoulos, dimitrios; vaporidi, katerina; kondili, eumorfia title: inspiratory effort and breathing pattern change in response to varying the assist level: a physiological study date: - - journal: respir physiol neurobiol doi: . /j.resp. . sha: doc_id: cord_uid: udokbcki aim: to describe the response of breathing pattern and inspiratory effort upon changes in assist level and to assesss if changes in respiratory rate may indicate changes in respiratory muscle effort. methods: prospective study of patients ventilated on proportional assist ventilation (pav+). at three levels of assist ( %- %- %), patients’ inspiratory effort and breathing pattern were evaluated using a validated prototype monitor. results: independent of the assist level, a wide range of respiratory rates ( - br/min) was observed when patients’ effort was within the accepted range. changing the assist level resulted in paired changes in inspiratory effort and rate of the same tendency (increase or decrease) in all but four patients. increasing the level in assist resulted in a % ( - %) decrease in inspiratory effort and a % ( - %) decrease in respiratory rate. the change in respiratory rate upon the change in assist correlated modestly with the change in the effort (r = . ). conclusion: changing assist level results in changes in both respiratory rate and effort in the same direction, with change in effort being greater than that of respiratory rate. yet, neither the magnitude of respiratory rate change nor the resulting absolute value may reliably predict the level of effort after a change in assist. assisted mechanical ventilation aims to assure adequate ventilation by assisting and partially unloading the respiratory muscles (pierson, ) . ideally, the level of assist should not only result in normal or near-normal arterial blood gases but also to normal or near-normal levels of inspiratory effort, to prevent both over-and under-assistance induced injury of the diaphragm . setting the level of ventilator assist in everyday practice relies mostly on the clinical estimation of inspiratory effort, as indicated by the breathing pattern -tidal volume (vt) and respiratory rate (rr)-and clinical signs of respiratory distress (boles et al., ; hansen-flaschen, ; hess, ; ray et al., ) . however, the relationship between ventilatory assist and inspiratory effort, tidal volume, and respiratory rate is complicated and multifactorial, affected by the patient's respiratory drive, ability to generate alveolar ventilation, and the mode of support (vaporidi et al., ) . therefore, although tidal volume and respiratory rate are commonly used in everyday practice to titrate the level of assist, the scientific evidence guiding assist titration to the patient effort is limited, derived from studies with a relatively small number of patients (berger et al., ; j o u r n a l p r e -p r o o f ] carteaux et al., ; giannouli et al., ; marantz et al., ) and do not consider the random/normal variability in breathing pattern, unrelated to the level of assist. the aim of this study was to ) characterize the responses of respiratory drive, respiratory effort, and breathing pattern to changing levels of ventilatory assist in critically ill patients and ) assess if changes in respiratory rate may indicate changes in respiratory drive and effort. to this end, during proportional assist ventilation with adjustable gain factors (pav+), noninvasive measurements of respiratory drive, effort (as indicated by inspiratory muscle pressure) were obtained at different levels of assist, using a validated prototype monitor (pvi) (kondili et al., ; younes et al., ) . contrary to conventional modes of assisted mechanical ventilation, pav+ permits the patients to select their desired breathing pattern as determined by feedback mechanisms of control of breathing (younes, ) . this study was conducted in the medical-surgical icu of the university hospital of heraklion between january and july after approval by the hospital ethics committee ( ). since the study protocol does not involve a therapeutic intervention and clinical or diagnostic interventions, it was considered as carrying no more than minimal risks, and informed consent was waived. patients were included in the study after at least hours of mechanical ventilation, when they fulfilled standard criteria for initiation of weaning from controlled mechanical ventilation (hemodynamic stability, reversal of cause of respiratory failure). exclusion criteria were: age under years, pregnancy, severe muscle weakness or cervical spine injury, uncontrolled pain, fever, or delirium, readiness for spontaneous breathing j o u r n a l p r e -p r o o f ] trial, and when pvi monitor was unavailable. the study was interrupted if the patient could not trigger the ventilator, developed respiratory distress, or became for any reason unstable (increase in vasopressor requirements, deterioration of oxygenation, etc.). at the time of the study, all patients were ventilated on assisted modes (pressure support or pav+). all patients were studied on pav+ at three different levels of assist %, %, and % at the peep set by the treating physician. each level of assist, applied randomly, was maintained for min. moreover, recordings were obtained for minutes at the mode selected by the treating physician (ps or pav+) before and immediately after pav+. arterial blood gases were obtained during the last minute of low ( %) and high ( %) level of assist. the pressure generated by the inspiratory muscles per breath (pmus) was evaluated as an index of effort and calculated on a breath-by-breath basis by a research prototype monitor (pvi monitor, yrt limited, winnipeg, canada) using a method described in detail previously. briefly, the inputs required by the monitor to calculate pmus are the airway pressure (paw) and flow (v′), whereas volume (v) was obtained by v′ integration. at least two points during expiration that satisfied passive conditions (i.e., flow was driven by the elastic recoil pressure) were automatically identified by the monitor. at these points, the equation of motion was applied, and elastance (erspvi) and resistance (rrspvi) of the respiratory system were calculated. using these values and the equation of motion, pmus was calculated in each breath. provide non-invasively measurement of pmus, as well as of tidal volume and respiratory rate in breath by breath basis (kondili et al., ; younes et al., ) . patient mechanical inspiratory time (ti) was measured as the interval between the beginning of pmus increase and the point at which pmus started to decline rapidly. patient mechanical expiratory time was measured as the remainder of the respiratory cycle. the rate of rise of pmus (dp/dt,) was calculated as the change in pmus during inspiration divided by ti and was used as an index of respiratory drive. the level of peepi during the different levels of assist was measured as the positive deflection of pmus from the onset of mechanical inspiration to the point of zero flow. additionally, the following data were collected: severity score on admission, etiology of respiratory failure, days on mechanical ventilation, icu, and hospital length of stay and outcome. the output of pvi monitor data was processed before analysis to optimize data quality (e.g., artifact rejection). from each -min period, the th to th min of the recording was selected for analysis. in each patient, for each variable and a given level of assist, the distribution of values was evaluated. means and sd were calculated after examining for normal distribution. the calculated means in each variable were used for comparisons among patients. between groups of patients or levels of assist, differences in continuous variables were as determined by the study design, at the end of the study period ( min), patients were placed again on the same ventilator settings used by the treating physician. thus, in each patient, recordings were available with the same ventilator settings at approximately min apart, while the patient's condition was considered stable (pre-and post-study). an analysis of ventilation variables in the pre-and post-study recordings was used to determine the variability (range of difference) of each variable in the 'stable' critically ill patient. we used ibm spss statistics for windows version (armonk, ny) for analysis. during months, critically ill patients were included in the study. the patients' characteristics are presented in table . patients were studied on the ± day of mechanical ventilation; the baseline measurements from the ventilator and the pvi monitor are presented in table . in the analysis of single patient data ( -min breath by breath analysis), and for all pvi variables, a normal distribution was found in more than % of cases, and thus, the mean values were used for comparison among patients. results were qualitatively similar when median values were used (data not shown). ventilatory variables in the pre-and post-study period were not different (table ) . this was true when the two ventilation modes (ps, pav+) were examined independently (data not shown). arterial blood gases were also not different before and after the study. the variability in tidal volume and respiratory rate, indicated by the coefficient of variation (tobin et al., ) , was % and %, respectively. the - range of change in each variable was calculated as an indicator of the variability in breathing pattern that can be expected in a relatively stable critically ill patient when ventilation settings have not been modified (table ) . we subsequently analyzed, independently of the level of assist, the correlation between indices of respiratory drive (dp/dt), effort (pmuspeak), and breathing pattern (tidal volume -vt and respiratory rate -rr). a very strong linear correlation was observed between respiratory drive and pmuspeak at each level of assist (r= . ). respiratory drive correlated weakly with respiratory rate (r= . ), but not with tidal volume. when respiratory drive and pmuspeak were within the accepted 'target' range for mechanically ventilated patients , a broad range of respiratory rate (r - : - br/min) was observed (figure ). finally, we examined the patterns of change of respiratory drive, pmuspeak, rr, and vt in response to changes in the level of assist. with increasing assist, small but statistically significant changes were observed in all variables (table ). the change in effort, in response to change in assist, was greater than the change in respiratory rate ( figure ). respiratory drive decreased as assist increased, and this change correlated strongly with the change in the effort (r= . ), but moderately with the change in respiratory rate (r= . ), and not with the change in tidal volume. the patterns of response to assist increase were characterized by a concomitant increase in tidal volume and decrease in respiratory rate, yet, these changes were mostly within the expected range of variation, and not specific for the change in effort (figure ) ). a significant change in respiratory rate, opposite to that of effort, was observed only in four patients ( %). the sensitivity and specificity of a decrease in respiratory rate to predict a decrease in effort was % and %, respectively, with a positive predictive value of %. yet, the change in respiratory rate correlated only modestly with the change in effort (r= . ) and the resulting inspiratory effort at high assist (r= . , figure ). in some patients (n= , %), effort did not decrease with increasing assist. the development of intrinsic peep due to increase in tidal volume ( cases) and the presence of high respiratory drive due to metabolic acidosis ( cases) were the most common causes of this phenomenon. this study in critically ill patients in the post-acute phase examined the changes in breathing pattern, respiratory drive and effort and their correlations, induced by changes of the level of assist. patients were studied using pav+, a mode that permits patients to choose their breathing pattern and monitored with pvi, a prototype monitor validated to estimate inspiratory muscle pressure (kondili et al., ; younes, ; younes et al., ) . the main findings of the study are: ) patients respond to changes in ventilatory assist mainly by changing effort per breath; ) when respiratory drive and/or effort are normal, a wide range of respiratory rate is observed; ) although respiratory rate changes towards the same direction as effort, neither the magnitude of change, nor the resulting value of respiratory rate are related to the level of effort, suggesting the limited role of respiratory rate in titrating assist to a target level of effort. in this study the correlation of indices of respiratory drive (dp/dt) and effort (pmus) was, as expected, very strong (de vries et al., ; mauri et al., ; vaporidi et al., ) . respiratory rate correlated weakly with respiratory drive, and most importantly, a wide range of breathing frequencies was observed in patients with relatively normal respiratory drive and effort. tachypnea was present in several patients with normal respiratory drive and pmus, and, although no patient exhibited hypoxemia, hyperactive delirium or fever at the time of the study, other causes of tachypnea, such as systemic inflammation, receptor stimulation or cortical stimulation could not be excluded (telias et al., ; vaporidi et al., ) . in addition, in our study, respiratory drive was estimated using the rate of increase of pmus, which in the presence of neuromuscular weakness underestimates the actual respiratory drive (the rate of increase of electrical activity of the respiratory center output). therefore, at the presence of neuromuscular weakness, respiratory center activity during inspiration may be high causing an increase in respiratory rate despite normal inspiratory pressure during inspiration. this observation is in line with several studies showing a higher than normal respiratory rate in critically ill patients (akoumianaki et al., ; giannouli et al., ; marantz et al., ) . moreover, a low respiratory rate was not uncommon, despite a high respiratory drive and effort, highlighting the inadequacy of respiratory rate as an indicator of respiratory drive and effort. this is not an unexpected finding as the respiratory rate in critically ill patients may be affected by several factors, most commonly sedation and opioid analgesia, which were also present in these patients (grap et al., ; mcgrane and pandharipande, ; vaporidi et al., ) . the response of critically ill patients to changes in assist was characterized overall by a decrease in respiratory drive, effort and respiratory rate, and an increase in tidal volume. patients changed their effort more often and to a greater extent than their respiratory rate upon change of assist and drive. this pattern of response is the same as the one observed in healthy subjects (duffin et al., ) . in our study in most patients, these changes of rr and vt were within the range of variability observed without a change in ventilator settings. moreover, this variability, for both rate and tidal volume, was found higher in the critically ill than in healthy individuals (tobin et al., ) . in mechanically ventilated patients a decrease in the respiratory rate in response to the increasing level of assist is usually considered as indicative of respiratory muscle unloading (esteban et al., ; esteban et al., ; sellares et al., ; yang and tobin, ) . this study identified that, indeed, a decrease in respiratory rate has a positive predictive value of % to predict a decrease in the inspiratory effort. however, this study also identified that it is only the direction of change and not the magnitude of the effect that can be predicted. thus, these results indicate that, although a change in effort in response to a change in assist can be predicted by the change in respiratory rate with reasonable accuracy, neither the absolute value of respiratory rate nor its change can indicate if the resulting effort is low, normal or high. some methodological issues and limitations of this study should be considered in the interpretation of results. first, the changes in breathing pattern were studied while the patients were ventilated only in pav+ mode. therefore, different changes in breathing pattern in response to changes in ventilator assist may be present during ventilation on psv. yet, a previous study has shown similar changes in patients' neural respiratory rate in response to varying the assist level between pav and psv (giannouli et al., ) . second, the estimation of inspiratory effort and respiratory drive was performed using the measurement of pmuspeak, instead of the gold standard method of trans-diaphragmatic pressure (pdi). however, we have previously shown that pmuspeak derived by pvi monitor provides an accurate estimation of inspiratory effort (kondili et al, ) . at different levels of assist during ventilation on pav+, pmuspeak was compared with transdiaphragmatic pressure (pdi), and the pressure developed by all respiratory muscles (pmus) -calculated with the campbell diagram and using chest wall mechanics measured at active and passive ventilation. no significant difference between pmuspeak, and pdi and pmus, in terms of timing, magnitude, shape, and the rate of pressure increase. setting the level of ventilator assist aims in adequate unloading of the respiratory muscles. in everyday clinical practice, the titration of assist usually aims to achieve a tidal volume of - ml/kg and a respiratory rate of - breaths/min. moreover, automated systems have been introduced to facilitate titration of assist, relying on measurements of tidal volume and respiratory rate. it is widely believed that high breathing rate may be indicative of excessive work of breathing, and that a decrease in respiratory rate with increasing the level of assist indicates unloading of respiratory muscles and thus adequate assist level. however, it has been shown that frequently tachypnea may be due to factors unrelated to respiratory load. the results of this study emphasize that respiratory rate is not a sensitive indicator of the patient's effort and that neither the magnitude nor the absolute change in the respiratory rate in response to varying the level of assist reflects the changes in inspiratory effort accurately. it is, therefore important, in clinical practice to avoid oversimplifications and assumptions such as that a relatively normal respiratory rate assures a normal level of inspiratory effort. during the j o u r n a l p r e -p r o o f ] recent covid- epidemic, it has been reported that patients with severe disease 'surpisingly' did not develop tachypnea and respiratory distress, an observation which is in line with the findings of this study, and not at all unexpected. in conclusion, the present study, in mechanically ventilated patients on the recovery phase of acute illness, showed that changing the assist level results in changes of inspiratory effort in more patients and to a greater magnitude, than of respiratory rate, though both effort and rate change almost always in the same tendency (either increase or decrease). yet, neither the magnitude of change nor the absolute value of respiratory rate can be used to quantitatively estimate the resulting respiratory effort after a change in the level of assist. the injurious effects of elevated or nonelevated respiratory rate during mechanical ventilation mechanism of relief of tachypnea during pressure support ventilation weaning from mechanical ventilation comparison between neurally adjusted ventilatory assist and pressure support ventilation levels in terms of respiratory effort assessing breathing effort in mechanical ventilation: physiology and clinical implications a model of the chemoreflex control of breathing in humans: model parameters measurement extubation outcome after spontaneous breathing trials with t-tube or pressure support ventilation. the spanish lung failure collaborative group effect of spontaneous breathing trial duration on outcome of attempts to discontinue mechanical ventilation. spanish lung failure collaborative group response of ventilator-dependent patients to different levels of pressure support and proportional assist sedation in adults receiving mechanical ventilation: physiological and comfort outcomes dyspnea in the ventilated patient: a call for patient-centered mechanical ventilation ventilator modes used in weaning estimation of inspiratory muscle pressure in critically ill patients response of ventilator-dependent patients to different levels of proportional assist oxygenation patients recovering from severe acute respiratory distress syndrome sedation in the intensive care unit indications for mechanical ventilation in adults with acute respiratory failure acute respiratory failure in the elderly: etiology, emergency diagnosis and prognosis diaphragm-protective mechanical ventilation lung-and diaphragm-protective ventilation in acute respiratory distress syndrome: rationale and challenges predictors of weaning after acute respiratory failure is my patient's respiratory drive (too) high? variability of resting respiratory drive and timing in healthy subjects respiratory drive in critically ill patients. pathophysiology and clinical implications a prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation proportional assist ventilation, a new approach to ventilatory support. theory a method for monitoring and improving patient: ventilator interaction the authors declare that there is no conflict of interest. this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. key: cord- - bmj qsv authors: buonanno, giorgio; stabile, luca; morawska, lidia title: estimation of airborne viral emission: quanta emission rate of sars-cov- for infection risk assessment date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: bmj qsv airborne transmission is a pathway of contagion that is still not sufficiently investigated despite the evidence in the scientific literature of the role it can play in the context of an epidemic. while the medical research area dedicates efforts to find cures and remedies to counteract the effects of a virus, the engineering area is involved in providing risk assessments in indoor environments by simulating the airborne transmission of the virus during an epidemic. to this end, virus air emission data are needed. unfortunately, this information is usually available only after the outbreak, based on specific reverse engineering cases. in this work, a novel approach to estimate the viral load emitted by a contagious subject on the basis of the viral load in the mouth, the type of respiratory activity (e.g. breathing, speaking), respiratory physiological parameters (e.g. inhalation rate), and activity level (e.g. resting, standing, light exercise) is proposed. the estimates of the proposed approach are in good agreement with values of viral loads of well-known diseases from the literature. the quanta emission rates of an asymptomatic sars-cov- infected subject, with a viral load in the mouth of copies ml- , were . quanta h- and quanta h- for breathing and speaking respiratory activities, respectively, at rest. in the case of light activity, the values would increase to . quanta h- and . × quanta h- , respectively. the findings in terms of quanta emission rates were then adopted in infection risk models to demonstrate its application by evaluating the number of people infected by an asymptomatic sars-cov- subject in italian indoor microenvironments before and after the introduction of virus containment measures. the results obtained from the simulations clearly highlight that a key role is played by proper ventilation in containment of the virus in indoor environments. expiratory human activities generate droplets, which can also carry viruses, through the atomization processes occurring in the respiratory tract when sufficiently high speeds are reached (chao et al., ; morawska, ) . indeed, during breathing, coughing, sneezing or laughing, toques of liquid originating from different areas of the upper respiratory tract are drawn out from the surface, pulled thin, and broken into columns of droplets of different sizes (hickey and mansour, ) . the content of infectious agents expelled by an infected person depends, among other factors, on the location within the respiratory tract from which the droplets originated. in particular, air velocities high enough for atomization are produced when the exhaled air is forced out through some parts of the respiratory tract which have been greatly narrowed. the front of the mouth is the site of narrowing and the most important site for atomization; since most droplets originate at the front of the mouth, the concentration of an infectious agent in the mouth (sputum) is representative of the concentration in the droplets emitted during the expiratory activities (morawska, ) . thus, knowledge of the size and origin of droplets is important to understand transport of the virus via the aerosol route. contrary to the findings of early investigations (duguid, ; jennison, ; wells, ) , subsequent studies involving optical particle detection techniques capable of measurements down to fractions of a micrometer suggested that the majority of these particles are in the sub-micrometer size range (papineni and rosenthal, ) . more recently, the growing availability of higher temporal and spatial visualization methods using high-speed cameras (tang et al., ), particle image velocimetry (chao et al., ) and, above all, increasingly accurate particle counters (morawska et al., ) allowed the detailed characterization and quantitation of droplets expelled during various forms of human respiratory exhalation flows (e.g. breathing, whispering, speaking, coughing). therefore, in recent years a marked development has occurred both in the techniques for detecting the viral load in the mouth and in the engineering area of the numerical simulation of airborne transmission of the viral load emitted. however, the problem of estimating the viral load emitted, which is fundamental for the simulation of airborne transmission, has not yet been solved. this is a missing "transfer function" that would allow the virology area, concerned with the viral load values in the mouth, to be connected with the aerosol science and engineering areas, concerned with the spread and mitigation of contagious particles. a novel approach is here presented for estimating the viral load emitted by an infected individual. this approach, based on the principle of conservation of mass, represents a tool to connect the medical area, concerned with the concentration of the virus in the mouth, to the engineering area, dedicated to the simulation of the virus dispersion in the environment. on the basis of the proposed approach, the quanta emission rate data of sars-cov- were calculated as a function of different respiratory activities, respiratory parameters, and activity levels. the quanta emission rate data, starting from the recently documented viral load in sputum (expressed in copies ml - ), were then applied in an acknowledged infection risk model to investigate the effectiveness of the containment measures implemented by the italian government to reduce the spread of sars-cov- . in particular, airborne transmission of sars-cov- by an asymptomatic subject within pharmacies, supermarkets, restaurants, banks, and post offices were simulated, and the reduction in the average number of infected people from one contagious person, r , was estimated. the approach proposed in the present work is based on the hypothesis that the droplets emitted by the infected subject have the same viral load as the sputum. therefore, if the concentration of the virus in the sputum and the quantity of droplets emitted with dimensions less than µm is known, the viral load emitted can be determined through a mass balance. in particular, the viral load emitted, expressed in terms of quanta emission rate (erq, quanta h - ), was evaluated as: ( ) where cv is the viral load in the sputum (rna copies ml - ), vbr is the volume of exhaled air per breath (cm ; also known as tidal volume), nbr is the breathing rate (breath h - ), nd is the droplet number concentration (part. cm - ), and vd(d) is the volume of a single droplet (ml) as a function of the droplet diameter (d). information about the viral load in terms of quanta is essential as the quantum represents the "viral load" considered in engineering science: in other words, an infected individual constantly generates a number of infectious quanta over time, where a "quantum" is defined as the dose of airborne droplet nuclei required to cause infection in % of susceptible persons. the volume of the droplet (vd) was determined on the basis of data obtained experimentally by (morawska et al., ): they measured the size distribution of droplets for different expiratory activities (e.g. breathing, whispering, counting, speaking), recognizing that such droplets present one or more modes occurring at different concentrations. in particular, in the study a particle size distribution with four channels was considered with midpoint diameters of d = . , d = . , d = . , and d = . µm. as an example, speaking was recognized as producing additional particles in modes near . and . µm. these two modes became even more pronounced during sustained vocalization. details of the aerosol concentrations at the four channels of the size distribution during each expiratory activity are reported in ( ) where j indicates the different expiratory activities considered (namely whispered counting, voiced counting, speaking, breathing) and ir (m h - ) is the inhalation rate, i.e. the product of breathing rate (nbr) and tidal volume (vbr), which is a function of the activity level of the infected subject. the quanta emission rate from equation ( ) can vary in a wide range depending on the virus concentration in the mouth, the activity level, and the different types of expiration. regarding the inhalation rate effect, the quanta emission rate calculations are shown for three different activity levels (resting, standing, and light exercise) in which the inhalation rates, averaged between males and females, are equal to . , . , and . m h - , respectively (adams, ; international commission on radiological protection, ). the pandemic of a novel human coronavirus, now named severe acute respiratory syndrome coronavirus (sars-cov- throughout this manuscript), emerged in wuhan (china) in late and then spread rapidly in the world (https://www.who.int/emergencies/diseases/novel- coronavirus- ). in italy, an outbreak of sars-cov- infections was detected starting from cases confirmed in lombardy (a northern region of italy) on february. the italian government has issued government a decree dated march concerning urgent measures to contain the contagion throughout the country. this decree regulated the lockdown of the country to counteract and contain the spread of the sars-cov- virus by suspending retail commercial activities, with the exception of the sale of food and basic necessities. it represents the starting point of a system with imposed constraints. among the measures adopted for the containment of the virus in italy, great importance was placed on the safe distance of m (also known as "droplet distance"). this distance was actually indicated by the world health organization as sufficient to avoid transmission by air, without any reference to the possibility of transmission over greater distances indoors (https://www.who.int/emergencies/diseases/novel-coronavirus- ). with this measure, along with the opening of only primary commercial establishments (such as pharmacies, supermarkets, banks, post offices) and the closure of restaurants, the italian government has adopted the concept of spacing (known as "social distancing") to prevent the spread of the infection. obviously, this limit per se would have no influence on the reduction of airborne transmission of the infection in indoor environments since this distance is compatible with the normal gathering of people in commercial establishments. actually, on an absolutely voluntary basis, and despite the continuous denials by the government on the risk of indoor airborne transmission, commercial associations have changed the methods of accessing their commercial spaces such as restaurants, pharmacies, supermarkets, post offices, and banks; for example, by forcing customers to queue outside. it is clear that the best choice in containing an epidemic is a total quarantine which, however, appears to have enormous costs and social impacts, especially in western countries. to the indoor microenvironments considered here were a pharmacy, supermarket, restaurant, post office, and bank whose dimensions are summarized in table . two different exposure scenarios were simulated for each microenvironment: before lockdown (b) and after lockdown (a). in the simulation of the scenario before lockdown, the microenvironments were run with no particular recommendations; thus, people enter the microenvironments and queue indoors, often resulting in overcrowded environments. since most of the indoor microenvironments in italy are not equipped with mechanical ventilation systems, the simulations were performed considering two different situations: natural ventilation (a typical value for an italian building equal to . h - was adopted, both natural ventilation and mechanical ventilation; in this case a slight increase in the air exchange rate (aer) for natural ventilation ( . h - ) was considered in order to take into account that the door was always kept open. the restaurant was not tested in the scenario after lockdown since such commercial activity was closed down as a consequence of the lockdown. for all the scenarios considered in the simulations, the infected individual was considered to enter the microenvironment as the first customer (alone or along with other individuals according to the scenarios summarized in table ). all the scenarios were simulated taking into account that the virus is able to remain viable in the air for up to hours post aerosolization as recently detected by (van doremalen et al., ); thus, if the infected individual remained inside the environment for minutes (e.g. pharmacy), the calculation of the quanta concentration, infection risk, and r was performed for up to hours and minutes (named "total exposure time" in table ). for restaurants the calculation was performed for hours considering that after hours (i.e. two groups . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint remaining inside for hour and minutes one after the other) the microenvironment was left empty. and nucci model is based on the rate of change in quanta levels through time; in particular, the differential equations for the change of quanta in a control volume as well as the initial conditions (here not reported for the sake of brevity) allowed to evaluate the quanta concentration in an indoor environment at the time t, n(t), as: where aer (h - ) represents the air exchange rate of the space investigated, n represents the initial number of quanta in the space, i is the number of infectious subjects, v is the volume of the indoor environment considered, and erq is the abovementioned quanta emission rate (quanta h - ) characteristic of the specific disease/virus under investigation. the equation was derived considering the following simplifying assumptions: the quanta emission rate is considered to be constant, the latent period of the disease is longer than the time scale of the model, and the droplets are instantaneously and evenly distributed in the room (gammaitoni and nucci, ). the latter represents a key assumption for the application of the model as it considers that the air is well-mixed within the modelled space. the authors highlight that in epidemic modeling, where the target is the spread of the disease in the community, it is impossible to specify the geometries, the ventilation, and the locations of the infectious sources in each microenvironment. therefore, adopting the well-mixed assumption is generally more reasonable than hypothesizing about specific environments and scenarios because the results must be interpreted on a statistical basis (sze to and chao, ). to where ir is the inhalation rate of the exposed subject (which is, once again, affected by the subject's activity level) and t is the total time of exposure (h). from the infection risk r, the number of susceptible people infected after the exposure time can be easily determined by multiplying it by the number of exposed individuals. in fact, equations ( ) and ( ) were adopted to evaluate the infection risk of different exposure scenarios of italian microenvironments hereinafter reported. the quanta emission rate used in the simulation of the scenario represents the average value obtained from the four expiratory activities (whispered counting, voiced counting, speaking, and breathing); the data are reported and discussed in the result sections. as discussed in the materials and methods section, the quanta emission rate, erq, depends on several parameters. in figure the erq (quanta h - ) trends are reported as a function of the viral load in the sputum (cv, rna copies ml - ) for different expiratory activities (whispered counting, voiced counting, speaking, breathing) and different activity levels (resting, standing, light exercise). to represent the large variabilities (over several orders of magnitude) of erq as a function of cv, the graph is reported on a bi-logarithmic scale. to benchmark the proposed approach for the estimation of the quanta emission rate, we considered the case of seasonal influenza for which more data are available in terms of both viral load in sputum and quanta emission rate. as an example, (hirose et al., ) found an average value of rna concentration in sputum for influenza equal to . × copies ml - . thus, applying the findings of the proposed approach in the case of a standing subject, a corresponding erq varying between . (breathing) and quanta h - (speaking) is estimated: this value is in good agreement with the quanta emission rates for influenza found in the scientific literature, from to quanta h - with a most frequent value of quanta h - (knibbs et al., ) . such variability in the quanta emission rates for influenza is due both to the method used to calculate it (rudnick and milton, ) and, especially, the viral load of the subject and the type of respiratory activity, which is typically not reported and discussed. light exercise quanta emission rates (erq) for a sars-cov- infected asymptomatic subject as a function of activity level (resting, standing, and light exercise) and respiratory activity (voiced counting, whispered counting, speaking, breathing). the data confirm the huge variations in the quanta emission rate, with the lowest value being for breathing during resting activity ( . quanta h - ) and the highest value being for speaking during light activity (more than quanta h - ). table -quanta emission rates (erq) for a sars-cov- infected asymptomatic subject (cv= copies ml - ) as a function of the activity level and respiratory activity. in this section, the results of the simulations performed for the microenvironments and exposure scenarios described in section . and summarized in table are reported. as an illustrative example, figure shows the quanta concentration (n(t)) and infection risk (r) trends as a function of time for two different exposure scenarios simulated for the pharmacy, i.e. before lockdown (b) in natural (nv) and mechanical ventilation (mv) conditions. the trends clearly highlight that the presence of the infected individual remaining inside for minutes leads to an increase in the quanta concentration in the volume: in particular, a higher peak of quanta concentration was recognized, as expected, for reduced ventilation (nv) with respect to the mechanical ventilation (mv). people entering the pharmacy after the infected individual are exposed to a certain quanta concentration during their -min time, and the resulting risk for their exposure (evaluated through equation ( )) is just a function of the quanta concentration trend. for example, people entering the microenvironment around the quanta concentration peak are at a higher risk than people entering the pharmacy later. figure shows an example of a customer entering at min and leaving at min : the risk for this -min exposure is . % in natural ventilation conditions and . % in mechanical ventilation conditions. during the entire exposure time of such a scenario ( hours and minutes), customers (after the infected individual) enter the pharmacy and each of them receive their own risk. in particular, the average risk of the customers is . % for nv conditions and . % for mv conditions, then leading to a r (among the customers) of . and . , to which must be added the r of the five pharmacists exposed for the entire period. similar trends, not shown here graphically for the sake of brevity, were obtained for all the scenarios investigated, then leading to the evaluation of the r for each of them as described in the methodology section. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint table ). the r data were calculated for an asymptomatic sars-cov- infected subject (cv= × copies ml - ) while standing; in particular, the average erq value among the different respiratory activities was considered ( quanta h - , table ). the exposed subjects were also considered to be standing (ir= . m h - ). the new regulations and methods of accessing the indoor environments that were applied in the conditions after lockdown (i.e. queuing outside, limited time spent in the environments, lower crowding index) were very effective; indeed, the r values were reduced by roughly %- % (for both natural and mechanical ventilation conditions) with respect to the corresponding pre- lockdown scenarios. as an example, for the natural ventilation scenario, the only critical microenvironment was the bank, since the r was > ; this was due to a crowding index that was higher than the post-office, which had a larger floor area but same number of customers. in contrast, all the r values for indoor environments equipped with mechanical ventilation systems were much lower than ( . the values obtained with this approach could vary significantly as a function of (i) the activity levels of both the infected subject and the exposed subjects; and (ii) the viral load in the sputum of the infected subject; therefore, in future studies, more specific exposure scenarios could be simulated on the basis of the findings proposed and discussed in this study. figure -r calculated for all the exposure scenarios (natural ventilation, mechanical ventilation; before lockdown, after lockdown) and microenvironments (pharmacy, supermarket, restaurant, post office, bank) under investigation considering an asymptomatic sars-cov- infected subject (cv= × copies ml - ) while standing (ir= . m h - ; erq= quanta h - ) and the exposed population, also standing. the present study proposed the first approach aimed at filling the gap of knowledge still present in the scientific literature about evaluating the viral load emitted by infected individuals. this information could provide key information for engineers and indoor air quality experts to simulate airborne dispersion of diseases in indoor environments. to this end, we have proposed an approach to estimate the quanta emission rate (expressed in quanta h - ) on the basis of the emitted viral load from the mouth (expressed in rna copies in ml - ), typically available from virologic analyses. such approach also takes into account the effect of different parameters (including inhalation rate, type of respiratory activity, and activity level) on the quanta emission rate. the suitability of the findings was checked and confirmed as it was able to predict the values of quanta emission rates of previous well-known diseases in accordance with the scientific literature. the proposed approach is of great relevance as it represents an essential tool to be applied in enclosed space and it is able to support air quality experts and epidemiologists in the management of indoor environments during an epidemic just knowing its viral load, without waiting for the end of the outbreak. for this purpose, it has been applied to the italian case which, at the time of writing, represents the country with the highest number of deaths from sars-cov- in the world, highlighting the great importance of ventilation in indoor microenvironments to reduce the spread of the infection. measurement of breathing rate and volume in routinely performed daily activities human performance laboratory, physical education department human performance 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approaches temporal profiles of viral load in posterior oropharyngeal saliva samples and serum antibody responses during infection by sars-cov- : an observational cohort study. the lancet infectious diseases uni -impianti aeraulici al fini di benessere. generalità, classificazione e requisiti. regole per la richiesta d'offerta, l'offerta, l'ordine e la fornitura aerosol and surface stability of sars-cov- as compared with sars-cov- calculating the potential for within-flight transmission of influenza a (h n ) on airborne infection: study ii. droplets and droplet nuclei clinical presentation and virological assessment of hospitalized cases of coronavirus disease in a travel-associated transmission cluster key: cord- -i wyhque authors: heider, philipp title: covid- mitigation strategies and overview on results from relevant studies in europe date: - - journal: nan doi: nan sha: doc_id: cord_uid: i wyhque in december , the first patients in wuhan, china were diagnosed with a primary atypical pneumonia, which showed to be unknown and contagious. since then, known as covid- disease, the responsible viral pathogen, sars-cov- , has spread around the world in a pandemic. decisions on how to deal with the crisis are often based on simulations of the pandemic spread of the virus. the results of some of these, as well as their methodology and possibilities for improvement, will be described in more detail in this paper in order to inform beyond the current public health dogma called"flatten-the-curve". there are several ways to model an epidemic in order to simulate the spread of diseases. depending on the timeliness, scope and quality of the associated real data, these multivariable models differ in the value of used parameters, but also in the selection of considered influencing factors. it was exemplarily shown that epidemics in their course are simulated more realistically by models that assume subexponential growth. furthermore, various simulations of the covid- pandemic were presented in an european perspective, compared against each other and discussed in more detail. it is difficult to estimate how credible the simulations of the pandemic models currently are, so it remains to be seen whether the spread of the pandemic can be effectively reduced by the measures taken. whether a model works well in reality is largely determined by the quality and scope of its underlying data. past studies have shown that countermeasures are able to reduce reproduction numbers or transmission rates in epidemics. in addition to that, the presented modelling study provides a good framework for the creation of subexponential-growth-models for assessing the spread of covid- . there are several ways to model an epidemic in order to simulate the spread of diseases. depending on the timeliness, scope and quality of the associated real data, these multivariable models differ in the value of used parameters, but also in the selection of considered influencing factors. it was exemplarily shown that epidemics in their course are simulated more realistically by models that assume subexponential growth. furthermore, various simulations of the covid- pandemic were presented in an european perspective, compared against each other and discussed in more detail. it is difficult to estimate how credible the simulations of the pandemic models are. whether a model works well in reality is largely determined by the quality and scope of its underlying data. past studies have shown that countermeasures are able to reduce reproduction numbers or transmission rates in epidemics. in addition to that, the presented modelling study provides a good framework for the creation of subexponential-growth-models for assessing the spread of covid- . on . . the sars-cov- virus arrived almost everywhere. nevertheless, there is disagreement about the measures to be taken against covid- around the world, while the news report frightening incidents. why is it so difficult for countries to find a common consensus on how to tackle the pandemic? virus pandemics spread across national borders with a time lag. therefore, while some countries are at an early stage of the crisis, as evidenced by the low number of new infections confirmed daily, other populations in the world may already be much more seriously affected. china and south korea, for example, are already planning to return to normal life ( , ) , but elsewhere the situation is becoming increasingly dramatic. these differences result in an inhomogeneous data situation; in addition, different fundamental conditions of countries make it difficult to mutually compare situations. creating simulation models that allow a (realistic) prediction of the pandemic virus spread is a difficult task. the basic theories on which such models are based are as old as they are complex. thus, with this thesis i would like to contribute to the understanding of these and to present results from previous publications relevant to this topic. scientists are not only making a special contribution to the general public by informing them about the dangers and ways to protect ourselves from them, but they also support politicians all over the world. at the moment, it is becoming clear how valuable scientific skills and experience are for assessing the situation and making quick decisions. a concept to mitigate the effects of the virus pandemic is being widely covered by the media. this is the current public health dogma "flatten-the-curve". this can be explained without further elaboration: the number of seriously ill persons should be kept low so that the national health system does not collapse due to a lack of beds in the intensive care units of the hospitals (icus). the outbreak of the disease in society is to be "slowed down", and the mortality rate is to be kept low. the concept "flatten-the-curve" is based on the frightening result obtained by comparing the results of statistical, epidemiological simulations of the pandemic with the number of intensive care beds available in the country. many of them conclude that without effective countermeasures, a collapse of the health system is to be expected. a model frequently used for simulating directly transmitted infectious diseases is the so-called "sir" model. this model is based on the nd nobel prize winner (who was awarded for his findings on malaria) for medicine/physiology, robert ross, as well as to the former researchers hilda hudson and kermack/mckendrick. the sir model assumes that during an epidemic, every person goes through the three states, s: "susceptible", i: "infected" and r: "recovered". since the number of people in each stage depends on the dynamics of the epidemic and thus on the time during the epidemic, the sir model can be described mathematically with differential equations ( ), which will not be discussed in detail in this work. it is often assumed that every epidemic initially spreads exponentially. due to the initially small number of cases detected, the spread normally goes unnoticed. however, experience has shown that epidemics slow down in the course of their spread and no longer show exponential growth ( ). this observation will be discussed in more detail in the following study. for its understanding, however, further foundations are necessary. an important indicator used to assess the risk of epidemic spread is the effective reproduction number rt. this indicates the average number of secondary infections per primary infection, i.e. how many more people are infected by an infected person at a given time. if the value rt falls below , the epidemic decreases, above the epidemic picks up speed. another key figure that should not be confused with the one just mentioned is the so-called "basic reproduction figure" r₀. it indicates how quickly an epidemic can spread at the beginning when all people in a population are susceptible to infection. to determine this important parameter, it is important to know the underlying "agent", its transmission and pathogenicity precisely and as generally as possible. trying to find a value of r for the covid pandemic online, one encounters different values, which vary greatly from . to . ( ) ( ) ( ) ( ) ( ) . to calculate the effective reproduction number, the basic reproduction number must already be known. to understand why this second one varies so much, one must understand what influences it. in the classical sir model, the reproduction number at the beginning of a pandemic, i.e. at time t = , is calculated as follows: r t= = r = β γ β is the initial transmission rate and γ the rate at which infected persons recover. r is a ratio of new infection rate to recovery rate and therefore dimensionless. the transmission rate β is generally calculated by the product of the contact rate c times the probability p with which contact between infected and susceptible persons leads to virus transmission, but in more complex models other influencing factors can be taken into account. the determination of both reproduction numbers is therefore always based on certain assumptions which are mathematically described in a model that can be based on different types of growth. this can be exponential (as most commonly used), or other growth processes, e.g. logistic or linear. these growth processes can be tested and compared with the presented sir model. in a publication by chowell et al ( ), published in october , for example, the dynamics of epidemics were examined using various basic concepts advanced sir models were used to determine how the predicted number of cases and the number of reproductions change over time and differ when exponential growth is assumed on the one hand and subexponential/polynomial growth on the other in a generalized growth model. in the course of this, three models were created and mathematically formulated, which consider different aspects: model takes into account a certain degree of clustering within society. this influences the way epidemics spread. taking this into account, model postulates that all people live in total c ̅ households of a certain size h and each household is part of a, to a certain degree, networked community. in the subsequent mathematical simulation of the model, it could be seen that a larger number of people in the community leads to more infected people, which is logical. it was also seen, however, that under the assumption of a subexponential/polynomial growth, the effective reproduction number decreases as the epidemic progresses. model considers a reactive change in human behaviour, with a resulting time-dependent change in the transmission rate. this is achieved by introducing a parameter q, which influences the transmission rate β. the results were similar: behavioural changes in society lead to a decrease in the reproduction number towards . model assumes that the population is unevenly, i.e. inhomogeneously mixed. for this purpose a parameter α is introduced in the mathematical formulas. the smaller it is (α < , α → ), the more it reduces the simulated epidemic spread as suspected, this model also behaves like the one mentioned above. higher inhomogeneity of society, lowers r more drastically over time. subsequently, all approaches were combined into one concept and the results were compared with real, historical data. the following conclusion could be drawn: models that assume exponential growth estimate the effective reproduction number to be higher than actually proven. in comparison, models such as the one presented, which does not assume exponential growth, calculate the case number and effective reproduction number r t in the advanced course of an epidemic, more realistically (see figure , figure ). comparing the results with the situation at the end of march , shown in figure , it can be seen that at this point in time, the curve for new cases in some countries begins to deviate from the exponential growth that would be linear-diagonal. assuming that many previous simulations have only considered exponential growth, this is a positive signal. it could mean that the effective reproduction number, as mentioned in the study, is actually lower than previously assumed. for the sake of completeness, reference should be made to the model known as "seir". here, the incubation time is also taken into account as another possible state ("exposed"). if this is higher, this reduces the number of patients at the peak of the epidemic, but extends the period of high exposure for the clinics, since "herd immunity" is reached later. -in a study published in by the bkk (german federal office for civil protection and disaster assistance), the results of the modelling of a hypothetical sars epidemic are found. the effect on the total population ( million) is simulated. in the study it is assumed that without measures, one infected person will infect an average of three others (initial reproduction number: r = ). with effective intervention (curfews, closure of universities/schools) this rate is reduced to . . countermeasures are assumed from day to since the first infected person was detected and the rate with hospitalized patients requiring intensive care is assumed to be between and %. furthermore, it is determined that the mortality rate at the age of years is % and a mild course of the disease occurs in % of cases. the simulation comes to the conclusion that at the peak of the epidemic about . million patients need intensive care. of these, an estimated are available under normal conditions in germany ( ). in comparison with other countries such as italy or great britain, this is a relatively high value, but according to the study results, the health care system would still collapse under the burden. in this model, the incubation period during which an infected person is not yet infectious is not taken into account. for covid- this is estimated to be about . days ( ). an essential factor that makes prognostic simulations more credible is knowing which countermeasures to spread, how well they work. however, since there are few general, evidencebased publications and no databases on this subject, assumptions must be made. the study presented by the german federal office bkk estimates the reduction of r through school closures, the prohibition of events and home quarantine at - . %. for comparison: reports (nonpeer-reviewed) from china even estimate a reduction of as much as - . % due to the very drastic measures against covid- in wuhan ( , ) . calculations from spain claim that the transmission of influenza can be reduced by a maximum of % by closing schools without curfew ( ) . this contrasts with observations from russia, which showed that school closure during the flu season reduces the daily contact rate (≠ reproductive index r ) with individuals by % for students and % for workers ( ) . only the results of these studies should be mentioned. these are not directly related to the current or future situation. however, it can be seen from the data that measures taken appear to be effective against the spread of infectious diseases. -the fact that science is currently exerting enormous influence on political decisions is shown by a recent publication by imperial college london, which caused the governments of great britain and the usa to rethink their course against the virus ( ) . the author and one of the directors of the renowned university, neil ferguson, is probably the english equivalent of the german doctors drosten and kekulé, to whom politics in this country is currently listening. the icl publication paints a gloomy picture of what lies ahead for the uk. without going into the economic consequences, it is based on the so-called "npi measures" (non-pharmaceutical-measures) taken in the usa in . measures to contain the spanish flu. the effectiveness of such "npis" is tested in the study using a statistical model which assumes exponential epidemic growth for the uk. the results will be presented in more detail below. the model assumes a reproduction number of r = . , a . % general death rate of tested and untested infected persons (infection-fatality-rate, short: ifr), a mean hospitalization rate of of . % among infected persons and an incubation period of . days. furthermore, it is assumed that symptomatic patients are % more infectious than asymptomatic patients, while a distribution parameter is additionally introduced to take into account "individual infectivity". as shown in the excerpt below, the authors make the proportion of hospitalized infected persons dependent on the age of the person. while ferguson used chinese data in a preprint paper from the beginning of march to calculate hospitalisation rates as shown in table ( ) , the figures in the study now published look somewhat more threatening, since it also takes into account the situation in italy (see table ). online simulation tools have also been published, one of which was developed by a research group led by richard neher at the university of basel. with this tool, (seir) simulations can be easily visualized in a browser. by default, the hospitalisation rate (severe-cases) is given there as follows, but it can be adjusted individually. the underlying model uses data on health care and demography of a given country. however, parameters are not (yet) adapted to current knowledge (as of . . , ( )). in order to adjust the simulation in the appendix to more recent data, we have therefore changed the parameters for the proportion of severe cases according to the icl paper as it can be seen in figure . in summary, the third assessment of the online tool shown is probably the most pessimistic, as it is based so far only on data from countries particularly affected by the crisis. it has been shown that a collapse of the health care system quickly pushes up the death rate. the icl, on the other hand, predicts a lower probability of hospitalisation and severe courses of disease in older patients ( +). it should be noted that the two important parameters, r and ifr, are currently undergoing continuous correction and also vary widely between different online simulations. in contrast to many other simulations, the oxford centre for evidence based medicine, for example, estimates the death rate at a significantly lower level and also corrected the prognosis downwards based on the figures from germany (ifr = . , as of march, , ) ( ) . the scientists first compared the effects of various very realistically defined measures. among them: • doing nothing • isolate cases of disease • isolate cases of disease and house quarantine • closure of schools and universities • isolate cases of disease, domestic quarantine and social distancing from + they concluded that, although a combination of measures is comparatively more effective, the effectiveness of all the measures described is not sufficient to reduce the transmission rate r sufficiently and prevent the system from collapsing. this picture is consistent with the estimates and calculations of the studies mentioned at the beginning ( , ) . this procedure is commonly referred to as "mitigation" strategy. the simulation for great britain showed that icu capacities will not be sufficient despite the measures presented. source: ( ) the researchers see the only way to get the transmission rate r from the specified original value of . to near or below as a combination of drastic measures, whereby a complete "lockdown", as is currently the case in parts of austria, is considered a (temporarily) safe option. the two remaining scenarios therefore envisage the following countermeasures: • isolate cases of disease, domestic quarantine and general social distancing -or -• isolate cases of disease, domestic quarantine, closure of schools and universities and general social distancing however, the results in figure also show that drastic measures for a limited period of five months only postpone the pandemic to a later point in time into winter and do not mitigate it. successful herd immunisation with a vaccine therefore remains necessary in this case. since this strategy, known as "suppression", is ultimately not an option, the researchers propose a special protocol instead: • permanent case isolation with subsequent quarantine up to a limit of covid- intensive care patients per week and school closures, as well as general social distancing from a limit of intensive care patients/week the researchers show in their simulation that it would be possible to maintain intensive care units for normal operation in this way. it should be mentioned in this sense that the duration of the prevention measures depends to a large extent on how well one manages to reduce r . assuming that the current reproduction number is . and that the alternating measures would be sufficient to reduce the value permanently, the study calculates that the proposed protocol would have to be adhered to in great britain for just under months. there are already differing opinions as to the feasibility of this strategy. whether a model works well in reality is largely determined by the quality and scope of its underlying data. although the simulation models available today are already very comprehensively designed (some of them even include global traffic flows and demographics in their datasets ( , - )), an unmanageable number of influencing factors remain, which cannot all be taken into account mathematically. depending on which model is used to determine the reproduction number, it will be lower or higher. if the growth curve begins to flatten out, it is probably worth adjusting the models and taking into account subexponential growth by assuming other growth processes as exponential growth, i.e. logistic growth or generalized growth, in order to realistically estimate r t . the presented study ( ) provides a good framework for such models to build on. whether, and which measures are sufficient for a permanent reduction of the reproduction number has not yet been confirmed. it is a fact, however, that a relaxation of restrictions or non-compliance with rules increases the transmission rate and can quickly lead to a renewed rise in the curve in the worst case. detection of such events through monitoring and rapid follow-up in case of occurrence offers potential to prevent this. in china, south korea and singapore, it seems that the spread of the virus is well under control. under the title "response to covid- in taiwan -big data analytics, new technology, and proactive testing" an interesting report on how data can be used to counteract the spread of the virus can already be found ( ) . if the presumed high number of asymptomatic infections is confirmed and the number of fatal infections remains unchanged, this could reduce the ifr (infection fatality rate) and thus also the simulation curves shown. among other factors, this may be one reason why the ifr is lower in countries that rely on rigorous testing of many citizens for covid- early on. large-scale immunological antibody testing will provide evidence of the current status of herd immunity in populations. it is difficult to estimate how credible the simulations of the pandemic models currently are, so it remains to be seen whether the spread of the pandemic can be effectively reduced by the measures taken. as the presented studies from the past have shown, countermeasures are basically able to reduce reproduction numbers or transmission rates in epidemics. the principle that biotechnologists are so keen to use in the production of modern drugs when working with transgenic organisms is unfortunately playing against us all this time: exponential growth. this must be prevented. enclosed is the result of the simulation for germany for the period until the end of april , which was created with the online tool provided by the neher research group from basel ( ). this is based on the assumption that the development of a vaccine takes - months and is then quickly available. according to this, the capacity of the intensive care units will not be exceeded by the number of serious cases until then (end of april ), or the overflow will be delayed. in the beginning, however, very tough measures will be necessary. it is assumed that hard measures such as social distancing will reduce the reproduction number by % from the initially assumed . to . . it is also assumed that it will increase again over time due to a beginning population dynamic after longer curfews. after four months with existing restrictions, measures will be eased and the transmission rate will continue to be maintained at - % until the end of april . whether this assessment of the reproductive rate, ifr, as well as the effectiveness of countermeasures is realistic, will become apparent in the near future, when more data on the course and immunity in germany and neighbouring countries will be available. the hospitalisation rate of patients (severe-cases), as well as the proportion of persons requiring intensive care (critical-cases), was adapted according to the icl paper from the uk ( ) . the result of the simulation can be seen in figure . of abbreviations: • : reproductive number • : general reproductive number • : effective reproductive number • ifr: infection-fatality-rate • icl: imperial college longon • bkk: bundesamt für bevölkerungsschutz und katastropenhilfe • icu: intensive-care-unit • ggm: generalized-growth-model (subexponential) • exp: exponential keywords sars-cov- , modeling, epidemiology, public health, forecasting, epidemic spread as coronavirus infections slow, south korea plans for life after social distancing. the wall street journal coronavirus: china's risky plan to revive the economy. financial times contributions to the mathematical theory of epidemics: iv. analysis of experimental epidemics of the virus disease mouse ectromelia characterizing the reproduction number of epidemics with early subexponential growth dynamics estimating clinical severity of covid- from the transmission dynamics in wuhan, china pattern of early human-to-human transmission of wuhan timevarying transmission dynamics of novel coronavirus pneumonia in china novel coronavirus -ncov: early estimation of epidemiological parameters and epidemic predictions early transmission dynamics in wuhan, china, of novel coronavirus-infected pneumonia university of basel. covid- scenarios the incubation period of coronavirus disease (covid- ) from publicly reported confirmed cases: estimation and application evolving epidemiology and impact of non-pharmaceutical interventions on the outbreak of coronavirus disease the impact of transmission control measures during the first days of the covid- epidemic in china estimating the impact of school closure on influenza transmission from sentinel data reactive school closure weakens the network of social interactions and reduces the spread of influenza behind the virus report that jarred the u.s. and the u.k. to action. the new york times global covid- case fatality rates [internet]: oxford centre for evidence-based medicine (cebm) the effect of travel restrictions on the spread of the novel coronavirus the gleamviz computational tool, a publicly available software to explore realistic epidemic spreading scenarios at the global scale response to covid- in taiwan: big data analytics, new technology, and proactive testing not applicable. ethics approval and consent to participate not applicable. not applicable. all data generated or analysed during this study are included in this published article [and its supplementary information files]. the authors declare that they have no competing interests the author did not receive any funding in connection with the creation of this work. key: cord- -q wqfeh authors: min, kyung-duk; kang, heewon; lee, ju-yeun; jeon, seonghee; cho, sung-il title: estimating the effectiveness of non-pharmaceutical interventions on covid- control in korea date: - - journal: j korean med sci doi: . /jkms. . .e sha: doc_id: cord_uid: q wqfeh background: the coronavirus disease (covid- ) pandemic has posed significant global public health challenges and created a substantial economic burden. korea has experienced an extensive outbreak, which was linked to a religion-related super-spreading event. however, the implementation of various non-pharmaceutical interventions (npis), including social distancing, spring semester postponing, and extensive testing and contact tracing controlled the epidemic. herein, we estimated the effectiveness of each npi using a simulation model. methods: a compartment model with a susceptible-exposed-infectious-quarantined-hospitalized structure was employed. using the monte-carlo-markov-chain algorithm with gibbs' sampling method, we estimated the time-varying effective contact rate to calibrate the model with the reported daily new confirmed cases from february th to march st ( weeks). moreover, we conducted scenario analyses by adjusting the parameters to estimate the effectiveness of npi. results: relaxed social distancing among adults would have increased the number of cases . -fold until the end of march. spring semester non-postponement would have increased the number of cases . -fold among individuals aged – , while lower quarantine and detection rates would have increased the number of cases . -fold. conclusion: among the three npi measures, social distancing in adults showed the highest effectiveness. the substantial effect of social distancing should be considered when preparing for the nd wave of covid- . the coronavirus disease (covid- ) pandemic has posed severe global health challenges with substantial damage to the world economy. until april th, , approximately million confirmed cases and more than , deaths were reported worldwide, while the global gross domestic product was estimated to have declined by imported cases. a schematic diagram of the meta-population compartment model with the seiqh structure is shown in fig. , and incorporated equations are described in detail in supplementary material . four types of parameters were included in the model: the rate at which exposed individuals become infectious (θ), detection rate (γ), quarantine probability (υ), and effective contact rate (β). the rate at which exposed individuals become infectious was reciprocal with the latent period; thus, the time between exposure and onset of infectiousness reflected the probability of transition from the exposed (e) to infectious (i) state in a given time unit. the latent period was employed as . days, considering that the incubation period was reported as . days and infectiousness could be developed one day before presenting symptoms. the detection rate was reciprocal with the infectious period, reflecting the time between the onset of symptoms and isolation. the infectious period used was . days, as the reported time gap between symptom onset and isolation is . days and the assumption that infected individuals start transmitting the virus one day before presenting symptoms. quarantine probability was defined as the proportion of quarantined people detected by contact tracing before they became infectious. the probability was set to % as status quo, considering that % of confirmed cases were detected before symptom onset in gyeonggi-do. effective contact rate is the product of contact rate and transmission probability per contact. as we used a discrete-time model for our analyses, the effective contact rate indicated the number of people who were infected by one infectious patient per time unit (day). due to the heterogeneity in the number of contacts between infectious individuals and between time periods, we employed time-dependent effective contact rates. different effective contact rates were used for each week for individuals aged +, and for each month for individuals aged / https://jkms.org https://doi.org/ . /jkms. . .e the population was categorized into five states: susceptible (s), exposed (e), infectious (i), quarantined (q), and hospitalized (h). the population was also stratified according to age: aged - (subscript "c") and aged + (subscript "a"). four types of parameters were used to determine the transition rates between the different states: the rate at which exposed individuals become infective (parameter θ), the detection (or isolation) rates of infectious individuals (parameter γ), quarantine probability (parameter ν), and the force of infection (parameter λ), which was time-varying and dependent on the number of infectious individuals and their effective contact rates. - . considering that the effective contact rate was not measurable, we estimated the timevarying effective contact rate by calibrating the model using daily reported confirmed cases. calibration was performed using a monte-carlo-markov-chain algorithm , with gibbs sampling. the parameters used in this study and their values are summarized in table . in this study, we included data from february th, six days before the first case of the religion-related large cluster was reported, reflecting the time gap between the onset of infectiousness and isolation the study period was seven weeks (until march st). the early phase of the covid- epidemic (from january th to february th) was excluded because the local transmission was not significant at that time. in this study, we evaluated the effectiveness of various npis, including social distancing in adults, spring semester postponement, diagnostic testing, and contact tracing, using the developed mathematical model and scenario analysis. weekly effective contact rates among adults within the study period were estimated by model calibration. regarding the estimated rates as status quo, increased effective contact rates were applied to simulate an epidemic situation by reduced intensity of social distancing in adults. to assess the effectiveness of social distancing after the religious gathering-related event, which was expected to increase the effective contact rate between weeks and , we performed scenario analysis by applying an increased contact rate between weeks and . as a severe-case scenario, we assumed a two times higher effective contact rate than the maximum estimated effective contact rate between weeks and . as a mild-case scenario, we assumed an effective contact rate equal to the maximum estimated effective contact rate between weeks and . spring semester initiation at the usual time (march nd) in elementary, middle, and high schools would have increased the contact rates among children and adolescents. herein, by estimating the level of increase in the contact rates, we determined the effectiveness of the effective contact rate among individuals aged + in week calibrated d β effective contact rate among individuals aged + in week calibrated d β effective contact rate among individuals aged + in week calibrated d β effective contact rate among individuals aged + in week calibrated d β effective contact rate among individuals aged + in week calibrated d β effective contact rate among individuals aged + in week calibrated d β effective contact rate among individuals aged + in week calibrated d φ ca multiplier for effective contact rate from individuals aged - to individuals aged + calibrated d φ ac multiplier for effective contact rate from individuals aged + to individuals aged - calibrated d a latent period was assumed as . days, considering that the reported incubation period of the virus is . days and that infected individuals start transmitting the virus one day before presenting symptoms; b infectious period was assumed to be . days, considering that the reported time between the onset of symptoms and isolation is . days and that infected individuals start transmitting the virus one day before presenting symptoms; spring semester postponement. to this end, we used varicella incidence data from the korea centers for disease control and prevention (kcdc). although etiology and transmissibility differ between the two diseases, we assumed an equivalent contact rate ratio before and after the school semester. kcdc provided weekly reported varicella incidence in individuals younger than years old. using simple susceptible-exposed-infectious-recovered (seir) compartment model with time-dependent effective contact rate, we estimated contact rate ratio (k ) between before (january and february) and after school opening (march and april) in and contact rate ratio (k ) between january and february in . the ratio "k " represented an increased contact rate after the opening semester in the previous year (without . the ratio "k " was used as an estimate of contact rate decrease, by comparing the contact rate in january (when the outbreak was not severe) and february (when voluntary social distancing was rampant in korea). in the scenario analysis, we applied a k *( /k ) times higher effective contact rate to child and adolescent groups from march nd to march st. the scenario analysis is described in detail in supplementary material . extensive contact tracing and diagnostic testing could reduce the risk of secondary transmission by quarantining exposed individuals before they become infectious and reducing the infectious period of covid- patients. non-extensive contact tracing and diagnostic testing were simulated by applying a decreased detection rate (increased infectious period) and quarantine probability. as an increased infectious period, we used . days because . days was the longest reported time between symptom onset and isolation, and infected individuals can start transmitting the virus one day before presenting symptoms. the decreased level of quarantine probability was set to % (half of the status quo). two sensitivity analyses were implemented considering uncertainty of parameters. the time gap between onset of infectiousness and symptoms was assumed as days in the first sensitivity analysis. in the second sensitivity analysis the time gap between onset of symptoms to detect or isolation was assumed as days following report from ki et al. and the assumption for the first sensitivity analysis was also applied. no ethical approval is required. the calibration results of the developed model are illustrated in fig. in this study, we estimated the expected epidemic size of covid- in korea, if social distancing among adults in march was more relaxed while maintaining the effective contact rate at a higher level than the status quo (fig. ) . the effective contact rate in week (beta ) showed the higher estimate than those in other weeks (beta - ). in the severe-case scenario, where the effective contact rates in weeks - were assumed as two times higher than estimated beta ( . , % cri = . - . ), , cases ( % cri = , - , ) would have been confirmed by the end of march, which is approximately times more than the status quo. in the mild-case scenario, where the effective contact rates in weeks - were assumed as same as estimated beta , , cases ( % cri = , - , ) would have been confirmed by the end of march, which is approximately . times more than the status quo. we also simulated the epidemic size in korea, in the case that the spring semester would begin on march nd, as usual (fig. ) . using varicella incidence in and as a model, we found that non-postponement of the semester would have increased the contact rate . fold ( % cri = . - . ) in the severe-case scenario and . -fold ( % cri = . - . ) in the mild-case scenario (supplementary material ) . using scenario analysis for the contact rate ratio of covid- , we showed that the number of confirmed cases among individuals aged - would have been , ( % cri = , - , ) and ( % cri = - ) assuming the severe-case scenario and mild-case scenario, respectively. these estimates are . times and . times higher than the status quo, respectively. note: the effectiveness of social distancing among adults was estimated by increasing the effective contact rate in individuals aged +. in the severe-case scenario, the effective contact rate in weeks - was assumed to be . ( % credible interval = . - . ), which was two times higher than the maximum estimated effective contact rate in weeks - . in the mild-case scenario, the effective contact rate in weeks - was assumed to be . ( % credible interval = . - . ), which was equal to the maximum effective contact rate estimated for weeks - . less strict quarantine measures and less extensive diagnostic testing would have resulted in , confirmed cases by the end of march, which is . times higher than the status quo (fig. ) . if the detection time (time between the onset of symptoms and isolation) was reduced to days and the quarantine probability was increased to %, more than , cases could have been averted by the end of march. however, if the isolation of infected individuals was delayed to days, and the quarantine probability was reduced to %, more than , additional cases would have been reported by the end of march. the parameters used in the scenario analysis are detailed in table , and the results are summarized in table . in the first sensitivity analysis, where longer time gap between onset of infectiousness and symptoms was assumed, both effectiveness of social distancing and school opening postponement increased but that of contact tracing decreased. in the second sensitivity analysis, where longer time gap between onset of infectiousness and symptoms and shorter time gap between symptom onset and isolation were assumed, the effectiveness of social distancing decreased but the effectiveness of school opening postponement and contact tracing increased. the effectiveness of the spring semester postponement was estimated by increasing the effective contact rate among individuals aged - . in the severe-case scenario, the highest effective contact rate between march nd and march st was . ( % credible interval = . - . ), which was . times higher than the effective contact rate estimated for february. in the mild-case scenario, the estimated effective contact rate from march nd to march st was . ( % credible interval = . - . ), which was . times higher than the effective contact rate estimated for february. / https://jkms.org https://doi.org/ . /jkms. . .e daily new cases cumulative cases the effectiveness of extensive diagnostic testing and contact tracing was estimated by decreasing the quarantine probability and detection rate. in the scenario analysis, the quarantine probability was reduced to %, which was half the status quo ( %). additionally, the detection rate was reduced to / . , reflecting a longer infectious period ( . days) than the status quo ( . days). (e) contour plot illustrating the variations in the additional cumulative cases by the end of march. scenario employed a higher effective contact rate among individuals aged + in weeks - (β to β ) to evaluate the effectiveness of social distancing. in mild case scenario, β which is the highest effective contact rate among β - , was applied to β - . in severe case scenario, twice higher effective contact rates were assumed than mild case scenario; b scenario employed a higher effective contact rate among individuals aged - in march (β ) to evaluate the effectiveness of school opening postponement. the increase level of effective contact rate for the school opening scenario was obtained from increase level of effective contract rate by school opening in march using a mathematical model for varicella among adolescence; c scenario employed a lower detection rate (γ) and quarantine probability (ν) to evaluate the effectiveness of extensive diagnostic testing and contact tracing; d effective contact rate-related parameters for status quo were estimated by calibration with reported data of confirmed covid- cases. a mathematical simulation model with a seiqh compartment structure was developed to evaluate the effectiveness of npi strategies for the covid- epidemic in korea, including social distancing, and extensive contact tracing and diagnostic testing. our findings highlighted the effectiveness of the npis employed and indicated that a steep rise in the epidemic curve would have been observed if they had not been implemented. notably, social distancing among adults was the most effective measure contributing to the control of the epidemic. although the estimated effectiveness varied as different parameters were assumed, the high effectiveness of social distancing in all sensitivity analysis showed robustness of the results. the reasonable fit of the calibrated model with reported daily new confirmed cases, from february th to march st, was shown by both visual examination and correlation analysis, although some extreme values such as cases on february th, was not replicated by the model. drastic reduction in the effective contact rate was estimated in both age groups in march. the decreasing trend was attributed to a decrease in contact rate rather than a decrease in transmission probability per contact because the transmissibility is not believed to be affected by the temperature. high contact rates among adults in weeks and reflected the religious super-spreading event that took place in korea. however, the high contact rates can be overestimated because the majority of confirmed cases from the religion-related event were detected by mass diagnostic testing which increased the number of confirmed cases in a short period of time. in weeks and , the median estimate of the contact rate was close to zero, which is unlikely in the real-life situation; hence, it should be interpreted as an extremely low mean contact rate among infectious patients. in the reallife situation, in weeks and , extensive and large-scale diagnostic testing and preemptive quarantine were implemented, especially among the attendees of the religious gathering. although some undetected infected individuals have spread the virus, the mean effective contact rate among all infectious individuals in that period was low. to simulate the drastic decline in new confirmed cases, a close-to-zero effective contact rate was used, which is / https://jkms.org https://doi.org/ . /jkms. . .e the time gap between onset of infectiousness and symptoms was assumed as days in a sensitivity analysis. a scenario employed a higher effective contact rate among individuals aged + in weeks - (β to β ) to evaluate the effectiveness of social distancing; b scenario employed a higher effective contact rate among individuals aged - in march (β ) to evaluate the effectiveness of school opening postponement; c scenario employed a lower detection rate (γ) and quarantine probability (ν) to evaluate the effectiveness of massive diagnostic testing and contact tracing. the time gap between onset of infectiousness and symptoms was assumed as days and the time gap between symptom onset and isolation was assumed as days in a sensitivity analysis. a scenario employed a higher effective contact rate among individuals aged + in weeks - (β to β ) to evaluate the effectiveness of social distancing; b scenario employed a higher effective contact rate among individuals aged - in march (β ) to evaluate the effectiveness of school opening postponement; c the maximum decrease rate that the compartment model can suggest (given the constant infectious period). although this is one of inherent limitations of compartment models, both model and real-life situation showed 'extremely-low level' of mean contact rate in weeks and . in weeks and , the effective contact rate increased; however, the rate was decreased in the subsequent week, when the korean government recommended social distancing. consistent with modeling studies in different countries, scenario analysis confirmed the effectiveness of npis. - notably, with relaxed social distancing, the number of cases could have been . - folds higher. the estimated effectiveness reported in this study is considerably higher than a previous study that predicted a . -fold higher number of infections in china in the absence of inter-city travel restrictions. this difference could be attributed to the early implementation of social distancing in korea. for example, during the period of the religion-related superspreading event, strict social distancing was imposed on citizens in daegu where the superspreading events occurred. in addition, travel to and from daegu was reduced and voluntary social distancing had also been implemented before the government announcement of official social distancing. consistent with this, walker et al. reported that implementation of suppression strategies in the early phases of an epidemic could be five times more effective than a late phase implementation. however, the differences in methods between studies could also contribute the different results. for example, the previous study used a seir structure for the model but we used a seiqh structure. in addition, the previous study estimated contact rate by population movement datasets, such as mobile phone data, which were not used in this study. kim et al. predicted that spring semester postponement would prevent at least cases in march, assuming that the transmission rate would increase -fold after the start of the semester. this estimate was similar to the estimate of our mild-case scenario analysis, which suggested additional cases among individuals aged - . additionally, both studies estimated a limited impact on adults. however, severe-case scenario analysis estimated an additional cases and the new number of cases was maintained. the maintaining trend implied potential impact after beginning of the spring semester. if the number of new cases is low, then the maintaining trend would produce low-burden, but in the severe epidemic situation, the maintaining trend would give high burden. the level of increase in the third scenario analysis was not profound, with a . -fold higher predicted number of cases. considering that a prolonged infectious period would increase the probability of super-spreading events, which was not considered in the model, the effectiveness of extensive contact tracing and diagnostic testing could have been underestimated in this study. lai et al. found that early case detection and isolation could reduce the number of infections by %. there are several limitations to this study. first, we added q compartment in this study compared to seir model in order to evaluate the effectiveness of contact tracing. however, uncertainties for some parameters should be considered. for example, although a constant detection rate and quarantine probability were assumed, these parameters could be timevarying and can be affected by the number of daily confirmed cases. for example, high number of daily confirmed cases could exhaust capacity for epidemiological investigation which leads to a decrease in detection rate and quarantine probability. extracting the relevant data from epidemiological studies could improve the simulation model. second, to minimize the complexity of the model structure, we assumed a homogenous contact rate among individuals aged +; however, a varying contact rate among different age groups is expected. third, individual characteristics, such as comorbidity, health behavior, or occupation, were not considered in our compartment models. future agent-based model studies are required to improve the predictions reported here by incorporating individual factors. fourth, transmissibility can be time-varying because viral load tends to change after the onset of symptoms. finally, we simplified the model structure to minimize uncertainty of parameters. for example, we did not differentiate asymptomatic, pre-symptomatic and symptomatic cases in this study, and the compartment i represented all these cases for simplification. in addition, the compartments were not classified by geographical regions. considering that the transmission probability, infectious period could be different by each type of infectious status and effective contact rate could be different by geographical regions, future studies with complex structure or microsimulation design could improve accuracy of models. in this study, we simulated the covid- epidemic in korea from february th to march st, using a compartment model with a seiqh structure, and estimated the time-varying effective contact rate by calibrating the model with reported daily new cases. using the model, we estimated the effectiveness of npis by assuming less strict social distancing, spring semester non-postponement, or less extensive diagnostic testing and contact tracing. without each of these npis, the number of covid- cases would have been considerably higher, highlighting the importance of npis. in particular, social distancing among adults was the most effective npi. covid- ): situation report, . geneva: world health organization the potential impact of covid- on gdp and trade: a preliminary assessment estimating the asymptomatic proportion of coronavirus disease (covid- ) cases on board the diamond princess cruise ship covid- : identifying and isolating asymptomatic people helped eliminate virus in italian village epidemiologic characteristics of early cases with novel coronavirus ( -ncov) disease in korea korean society for antimicrobial therapy, korean society for healthcare-associated infection control and prevention the global impact of covid- and strategies for mitigation and suppression the incubation period of coronavirus disease (covid- ) from publicly reported confirmed cases: estimation and application viral load of sars-cov- in clinical samples covid- ) gyeonggi daily report, data as discrete time modelling of disease incidence time series by using markov chain monte carlo methods a tutorial introduction to bayesian inference for stochastic epidemic models using markov chain monte carlo methods feasibility of controlling covid- outbreaks by isolation of cases and contacts evaluation of heating and chemical protocols for inactivating sars-cov- impact of non-pharmaceutical interventions (npis) to reduce covid- mortality and healthcare demand. london: imperial college covid- response team the effect of human mobility and control measures on the covid- epidemic in china effect of non-pharmaceutical interventions for containing the covid- outbreak in china school opening delay effect on transmission dynamics of coronavirus disease in korea: based on mathematical modeling and simulation study projecting social contact matrices in countries using contact surveys and demographic data viral dynamics in mild and severe cases of covid- key: cord- -osol wdp authors: ma, junling title: estimating epidemic exponential growth rate and basic reproduction number date: - - journal: infect dis model doi: . /j.idm. . . sha: doc_id: cord_uid: osol wdp the initial exponential growth rate of an epidemic is an important measure of the severeness of the epidemic, and is also closely related to the basic reproduction number. estimating the growth rate from the epidemic curve can be a challenge, because of its decays with time. for fast epidemics, the estimation is subject to over-fitting due to the limited number of data points available, which also limits our choice of models for the epidemic curve. we discuss the estimation of the growth rate using maximum likelihood method and simple models. this is a series of lecture notes for a summer school in shanxi university, china in . the contents are based on ma et al. (ma, dushoff, bolker, & earn, ) . we will study the initial exponential growth rate of an epidemic in section , the relationship between the exponential growth rate and the basic reproduction number in section , an introduction to the least square estimation and its limitations in section , an introduction to the maximum likelihood estimation in section , and the maximum likelihood estimation of the growth rate in section . epidemic curves are time series data of the number of cases per unit time. common choices for the time unit include a day, a week, a month, etc. it is an important indication for the severeness of an epidemic as a function of time. for example, fig. shows the cumulative number of ebola cases during the e ebola outbreak in western africa. the cumulative cases during the initial growth phase form an approximately linear relationship with time in log-linear scale. thus, in linear scale, the number of deaths increases exponentially with time. the mortality curve (the number of deaths per unit time) shows a similar pattern, as demonstrated by the daily influenza deaths in philadelphia during the influenza pandemic shown in fig. . in fact, most epidemics grow approximately exponentially during the initial phase of an epidemic. this can be illustrated by the following examples. where s is the fraction of susceptible individuals, i is the fraction of infectious individuals, and r is the fraction of recovered individuals; b is the transmission rate per infectious individual, and g is the recovery rate, i.e., the infectious period is exponentially distributed with a mean =g. linearize about the disease-free equilibrium (dfe) ð ; ; Þ, di dt zðb À gÞi: ( ) thus, if b À g > , then iðtÞ grows exponentially about the dfe. in addition, initially, sz , thus, the incidence rate (number of new cases per unit time) c ¼ bsi also increases exponentially. it is similar for an susceptible-exposed-infectious-recovered (seir) model, as illustrated by the following example. example . lets consider an seir model: where e is the fraction of latent individuals (infected but not infectious), s the rate that latent individuals leaving the class, i.e; , the mean latent period is exponentially distributed with mean =s; s, i, r, b and g are similarly defined as in example . again, ð ; ; ; Þ is a disease free equilibrium representing a completely susceptible population. linearize about this equilibrium, the equations for e and i are decoupled, and become de dt note that the jacobian matrix j ¼ Às b s Àg ! has two real eigenvalues, namely, l ¼ Àðs þ gÞ þ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi ðs À gÞ þ sb q ; l ¼ Àðs þ gÞ À ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi ðs À gÞ þ sb q : thus, about the dfe, the solution of the model is asymptotically exponential with a rate l . similar to example , the incidence rate also grows exponentially initially. in general, suppose the infection states of an individual can be characterized by the following vector ð s ! ; i ! Þ, where s ! represents multiple susceptible states, and i ! represents multiple infectious (or latent) states. we also use s ! and i ! represent the number of individuals in each state. also assume that the epidemic can be modeled by the following generic system Þ is a dfe, and the initial number of infectious individuals i ! ð Þ is very small, then, initially, the dynamics of i is governed by the following linearized system if the def is unstable, then iðtÞ grows asymptotically exponentially. . the exponential growth rate and the basic reproduction number the exponential growth rate is, by itself, an important measure for the speed of spread of an infectious disease. it being zero is, like the basic reproduction number r ¼ , a disease threshold. the disease can invade a population if the growth rate is positive, and cannot invade (with a few initially infectious individuals) if it is negative. in fact, it can be used to infer r .there are two approaches to infer r from the exponential growth rate, a parametric one, and a non-parametric one. for the parametric approach, we need an underlying model that gives both the growth rate and r . example . consider the sir model ( ) in example . note that ð ; ; Þ is an disease free equilibrium, representing a completely susceptible population. as we discussed above, the exponential growth rate is l ¼ b À g. note that the basic reproduction number is r ¼ b=g . if, for example, g is estimated independently to l, then, lets look at a more complicated example. express b in terms of l and substitute it into r , then thus, if the mean infectious period =g and the mean latent period =s can be independently estimated on l, then r can be inferred from l. typically, for an epidemic model that contains a single transmission rate b, if all other parameters can be estimated independently to the exponential growth rate l, then l determines b, and thus determines r . models can be overly simplified for mathematical tractability. for example, both the sir model in example and the seir model in example assume exponentially distributed infectious period. however, the infectious period and the latent period are mostly likely not exponential. wallinga and lipsitch (wallinga & lipsitch, ) developed a non-parametric method to infer the basic reproduction number from the exponential growth rate without assuming a model. let hðaÞ be the probability that a random individual remain infectious a time units after being infected (i.e., a is the infection age); bðaÞ is the rate of transmission at the infection age a. then, tðaÞ ¼ hðaÞbðaÞ is the transmissibility of a random infectious individual at the infection age a, assuming that the whole population is susceptible. thus, in addition, we assume that the population is randomly mixed, i.e., every pair of individuals have identical rate of contact. let cðtÞdt be the number of new infections during the time interval ½t;t þ dt, that is, cðtÞ is the incidence rate, and sðtÞ be the average susceptibility of the population, i.e., the expected susceptibility of a randomly selected individual. in addition, new infections at time t is the sum of all infections caused by infectious individuals infected a time unit ago (i.e., at time t À a) if they remain infectious at time t (with an infectious age a) and their contact is susceptible. that is, and thus cðtÞ ¼ sðtÞ to compute r , we need to normalize tðaÞ as a probability density function, note that wðaÞda is the probability that a secondary infection occurs during the infection age interval ½a; a þ da. that is, wðaÞ is the probability density function of the generation time, i.e., the time from being infected to generate a secondary infection. this generation time is also called the serial interval. with the serial interval distribution wðtÞ, this means that the cðtÞ is only determined by r , wðtÞ and sðtÞ. at the beginning of an epidemic, where the epidemic grows exponentially (with an exponential growth rate l), sðtÞz and cðtÞ ¼ c e lt where c is the initial number of cases at where mðxÞ ¼ r ∞ e xa wðaÞda is the moment generating function of the serial time distribution wðaÞ. equation ( ) links the exponential growth rate to the basic reproduction number though the serial interval distribution only. that is, if we can estimate the serial interval distribution and the exponential growth rate independently, that we can infer the basic reproduction number. note that the serial interval distribution wðtÞ can be estimated independently to the exponential growth rate. for example, it can be estimated empirically using contact tracing. alternatively, one can also assume an epidemic model. here we discuss a few simple examples. example . consider an sir model. let fðaÞ be the cumulative distribution function of the infectious period, and a constant transmission rate b. the probability that an infected individual remains infectious a time units after being infected is and thus the transmissibility is tðaÞ ¼ b½ À fðaÞ; and the serial interval distribution is where m is the mean infectious period. for the special case that the infectious period is exponentially distributed with a rate g, i.e., fðaÞ ¼ À e Àga , this model becomes model ( ). then the density function of serial interval distribution is which is identical to the density function of infectious period distribution. the moment generating function is note that the exponential growth rate is l ¼ b À g, then lets consider a more complex example with multiple infected states. example . consider an seir model with a constant transmission rate b. let fðaÞ and gðaÞ be the cumulative distribution functions of the infectious period and the latent period, respectively. given the latent period t l ¼ [ a, the probability that an infectious individual is infectious a time units after being infected is À fða À [Þ:thus, hence, the serial interval distribution is for the special case that the latent period is exponentially distributed with a rate s (i.e., fðaÞ ¼ À e Àga ) and the latent period is exponentially distributed with a rate s (i.e., gðaÞ ¼ À e Àsa ), this model becomes model ( ), and wðaÞ ¼ gse Àga z a e ðgÀsÞs ds ¼ ðge Àga ÞÃðse Àsa Þ: that is, if both distributions are exponential, the serial interval distribution is the convolution of the latent period distribution and the infectious period distribution. in this case, the basic reproduction number is where m i ðxÞ and m l ðxÞ are the moment generating functions of the infectious period and latent period, respectively. in equation ( ), r ðtÞ ¼ r sðtÞ is the reproduction number, and thus this equation can be used to estimate the production number at any time t during the epidemic given the incidence curve cðtÞ, namely, this is similar to, but different from, the nonparametric method developed by wallingua and teunis (wallinga & teunis, ) . the least squares method is one of the most commonly used methods for parameter estimation in mathematical biology. this method is in fact a mathematical method. for a family of curves f ðt; q ! Þ, where q ! r m is a vector of parameters of the family, this method finds the curve f ðt; b qÞ in the family that minimizes the distance between the curve and a set of points , and x ! be the euclidean norm in r n , then the mathematical formulation of the least squares method is where argmin gives the parameter q ! that minimizes the objective function. for our purpose, the observations fðt i ; x i Þg nÀ i¼ is the epidemic curve, i.e., x is the number of initially observed cases, and x i is the number of new cases during the time interval ðt iÀ ; t . we aim to find an exponential function f ðt; c ; lÞ ¼ c e lt that minimizes its distance to the epidemic curve, i.e., the parameters q ¼ ðc ; lÞ. there are two commonly use methods to estimate the exponential growth rate l: . nonlinear least square to fit to f ðt; c ; lÞ ¼ c e lt directly; . linear least square to fit fðt i ; lnx i Þg to ln f ðt; c ; lÞ ¼ lnc þ lt. the nonlinear least squares method does not have an analytic solution. numerical optimization is needed to solve the minimization problem ( ). the linear least square method has an analytic solution: let [ ¼ lnc , then the least squares problem becomes the objective function is a quadratic function of [ and l, thus, the minimum is achieved at i¼ y i , which represents the average of any sequence fy i g n i¼ , then, and thus the best fit exponential growth rate ls b l ¼ do these two methods yield the same answer? to compare, we simulate an epidemic curve of the stochastic seir model in example , using the gillespie method (gillespie, ) . the simulated daily cases (number of individuals showing symptom on a day) are then aggregated into weekly cases. then, we use both methods to fit an exponential curve to the simulated epidemic curve. the simulated epidemic curve and the fitting results are shown in fig. . this exercise illustrates a challenge of fitting an exponential model to an epidemic curve: how to determine the time period to fit the exponential model. the exponential growth rate of an seir model decreases with time as the susceptible population decreases. in fig. , the epidemic curve peaks in week . we choose a sequence of nested fitting windows starting in the first week and ending in a week w for w ¼ ; ;…; . the seir model has an asymptotic exponential growth, so the fitted exponential growth rate is not monotonic near the beginning of the epidemic. for larger fitting windows, both methods give an exponential growth rate that decreases with the length of the fitting window. we need more data points to reduce the influence of the stochasticity. however, using more data points also risks of obtaining an estimate that deviates too much from the true exponential growth rate. there is no reliable method to choose a proper fitting window. fig. also shows that the linear and nonlinear least squares methods may not yield the same estimate. this is because of a major limitation of both least squares methods: they implicitly assume that the deviations jx i À f ðt i ; q ! Þj carry identical weights. with the nonlinear method, later data points (at larger times) deviate more from the exponential curve than the earlier data points, because the exponential growth slows down with time. thus, the method is more biased to the later data points. with the linear method, the deviations in lnx i are more even than in x i , and thus the linear method is less biased to the later data points than the nonlinear method does. the least squares method, as mentioned above, is a mathematical problem. it does not explicitly assume any error distributions, and thus cannot give us statistical information about the inference. for example, if we use two slightly different fitting windows and get two slightly different estimates, is the difference of the two estimates statistically significant? such a question cannot easily be answered by the least squares method. interestingly, the least squares methods make many implicit assumptions to the deviations. we have mentioned the implicit equal-weight assumption above. it also implicitly assumes that the order of the observations does not matter, and that positive and negative deviations are equivalent. thus, they implicitly assume that the deviations are independently identically and symmetrically distributed. in statistics, the least squares method is commonly used in linear and nonlinear regression with an addition assumption that the errors are independently and identically normally distributed. however, these assumption on the errors may not be appropriate. for example, the new cases at time t þ may be infected by those who are infected at time t. thus, the number of new cases at different times may not be independent. also, the number of cases is a counting variable, and thus its mean and variance may be closely related, meaning that the error may not be identically normally distributed. in the next section, we address some of these problems using the maximum likelihood method. the maximum likelihood method is a commonly used statistical method for parameter inference; see, e.g., [(bolker, to construct the likelihood function we need to make assumptions on the error distribution. there are two types of error: the process error and the observation error. the observation error is the error in the observation process. for example, most people with influenza do not go to see a doctor, and thus there is no record of these cases, resulting in an under-reporting of the number influenza cases. also, many influenza related deaths are caused by complications such as pneumonia, and influenza may not be recorded as the cause. typos, miscommunication, etc, can all result in observation errors. the process error originates from the stochasticity of the system that is independent to observation. for example, the disease dynamics is fig. . the simulated seir epidemic curve (upper) and the fitted exponential growth rate as a function of the end of the fitting window (lower). the epidemic curve is simulated stochastically from the seir model in example using the gillespie method (gillespie, ) with the parameters b ¼ : , s ¼ , g ¼ : , the rates have a time unit of a day. the daily cases are then aggregated by week. the data points are taken at times t i ¼ i, i ¼ ; ; ; … weeks. the theoretical exponential growth rate is l ¼ : per week. intrinsically stochastic. the time that an infectious individual recovers, and the time that a susceptible individual is infected, are all random variables that affects the number of new infections at any time, even if we eliminate all observation errors. these two types of errors have very different nature, and thus need very different assumptions. for example, it is reasonable to assume that observation errors are independent to each other, but process errors at a later time are commonly dependent on the process errors at earlier times. if observation errors are large and process errors are negligible, then we assume that the random variable x i corresponding to the observation x i is independently distributed with a probability mass function p i ðk; q ! Þ where k is the values that x i can take. then, the likelihood function is the maximization of this likelihood function rarely has an analytic solution, and commonly needs to be solved numerically. note that each factor (probability) can be very small, and thus the product may be very difficult to minimize numerically because of rounding errors (from the binary representation of real numbers in computers). it is a common practice to maximize the log-likelihood function for example, we assume that the number of cases xðt i Þ at time t i is independently poisson distributed with mean m i ¼ c e lti . then, the log-likelihood function note that the observed cases x i are constants, and thus the last term can be ignored for maximization. thus, this maximization problem can only be solved numerically. we choose poisson distribution because its simple form greatly simplifies the log-likelihood function. in addition, it does not introduce more parameters, which is valuable to avoid over-fitting when the number of data points available is small. if the process error is not completely negligible, then choosing an overly dispersed distribution, such as the negative binomial distribution may be desirable. a negative binomial distribution has two parameters, the success probability q ! and the shape parameter r > . for simplicity, we assume that the shape parameter r is the same at each time t i , and will; be estimated together with the model parameters q ! ; but q depend on t i . the probability mass function is and the log-likelihood function is again, the last term can be ignored for the optimization problem. in addition, there is a constraint r > . if process errors are large and observation errors are negligible, then we cannot assume that the observed values x iþ and x i are independent to each other. instead, for all i ¼ ; ; …; n À , we compute the probability mass function of x iþ given fx j ¼ x j g i j¼ , namely, q iþ ðk; q ! fx j g i j¼ Þ. then, the likelihood function is for simplicity, assume that x iþ is poisson distribution with mean m iþ ¼ x i e lðtiþ ÀtiÞ . note that, since we assumed no observation error, the initial condition c ¼ x is exact, and thus there is a single parameter l for the model. thus, and thus the log-likelihood function is x iÀ e lðt i Àt iÀ Þ þ x i lðt i À t iÀ Þ þ x i lnx i À lnx i !: again, the last two terms can be ignored in maximization because they are constants. thus, l ¼ argmax l x iÀ e lðt i Àt iÀ Þ þ ðt i À t iÀ Þx i l: it is much harder to formulate the likelihood function if process errors and observation errors must both be considered. we can simplify the problem by ignoring the process error and use an overly dispersed observation error distribution as a compensation. note that this simplification mainly affects the confidence intervals. the maximum likelihood method gives a point estimate, i.e., one set of parameter values that makes it mostly likely to observe the data. however, it is not clear how close the point estimates are to the real values. to answer this question we use an interval estimate, commonly known as a confidence interval. a confidence interval with a confidence level a is an interval that has a probability a that contains the true parameter value. a commonly used confidence level is %, which originates from a normal distribution. if a random variable x is normally distributed with a mean m and a standard deviation s, then the probability that x ½m À s; m þ s is %. the confidence interval can be estimated using the likelihood ratio test [ (bolker, ), p. ] . let c q !^b e the point estimate of the parameters. a value l is in the % confidence interval is equivalent to accepting with % probability that l is a possible growth rate. to determine this we fit a nested model by fixing the growth rate l ¼ l , suppose its point estimate is b q . we then compute the likelihood ratio the wilks' theorem (wilks, ) guarantees that, as the sample size becomes large, the statistics À lnl ¼ ½[ð b qÞ À[ð b q Þ is c distributed with a degree of freedom . we thus can compare À lnl with the % quantile of the c distribution and determine if l should be in the confidence interval or not. we can thus perform a linear search on both sides of the point estimate to determine the boundary of the confidence interval. we still have not addressed the problem of choosing a fitting window for an exponential model. recall that the challenge arises because the exponential growth rate of an epidemic decreases with time. instead of finding heuristic conditions for choosing the fitting window, we circumvent this problem by incorporating the decrease of the exponential growth rate into our model. we have two choices, using either a mechanistic model such as an sir or seir model, or a phenomenological model. naturally, if we know that a mechanistic model is a good description of the disease dynamics, fitting such a model to the epidemic curve is a good option (see, e.g., (chowell, ammon, hengartner, & hyman, ; pourabbas, d'onofrio, & rafanelli, ) ,). we use an sir model as an example. for simplicity, we assume that the process error is negligible, and the incidence rate is poisson distributed with a mean cðtÞ given by an sir model (cðtÞ ¼ bsin where n is the population size). to construct the log-likelihood function, we need to calculate cðtÞ, i.e., numerically solve the sir model. to do so, we need the transmission rate b. the recovery rate g, the initial fraction of infectious individuals ið Þ ¼ i (with the assumption that rð Þ ¼ , sð Þ ¼ À i , and thus i determines the initial conditions), in addition to the population size n. thus, the parameters of the model is q ! ¼ ðb; g; i ; nÞ. thus the log-likelihood function is (ignoring the constant terms) where the number of new cases cðt i Þ in the time interval ½t i ; t iþ is cðt i Þ ¼ sðt iþ Þ À sðt i Þ ; and sðt i Þ is solved numerically from the sir model. thus, [ implicitly depend on b, g and i through sðtÞ. one draw back using such a mechanistic model is its high computational cost, since each evaluation of the log-likelihood function requires solving the model numerically, and numerical optimization algorithms can be very hungry on function evaluations, especially if the algorithm depends on numerical differentiation. another draw back is that these mechanistic models can be overly simplified, and may not be a good approximation to the real disease dynamics. for example, for seasonal influenza, due to the fast evolution of the influenza virus, individuals have different history of infection, and thus have different susceptibility to a new strain. yet simple sir and seir models assume a population with a homogeneous susceptibility. thus using a simple sir to fit to an influenza epidemic may be an over simplification. however, realistic mechanistic models can be overly complicated, and involve too many parameters that are at best difficult to estimate. for example, a multi-group sir model depends on a contact matrix consisting of transmission rates between groups, which contains a large number of parameters if the model uses many groups. if all we need to estimate is the exponential growth rate, we only need a model that describes the exponential growth that gradually slows down. most cumulative epidemic curves grow exponentially initially, and then saturates at the final epidemic size. a simple phenomenological model can be used to describe the shape of the cumulative epidemic curve, but the model itself may not have realistic biological meaning. however, if simple mechanistic models cannot faithfully describe the epidemic process, using a simple phenomenological model with an analytical formula may be a better choice, at least numerically, because repetitively solving a system differential equations numerically, and differentiating the log-likelihood function numerically, can both be avoided with the analytical formula. here we discuss some examples for such models. the logistic model is the simplest model that shows an initial exponential growth followed a gradual slowing down and a saturation. the cumulative incidences cðtÞ (the total number of cases by time t) can be approximated by d dt cðtÞ ¼ rcðtÞ À cðtÞ k : where r is the exponential growth rate, and k ¼ lim t/∞ cðtÞ. let c ¼ cð Þ, its solution is the new cases cðt i Þ in a time period ½t i ; t iþ is thus the model parameters are q ! ¼ ðr; k; c Þ. note that it is less than the number of parameters of the simplest mechanistic model (i.e., the sir model). the logistic model has a fixed rate of slowing down of the exponential growth rate. to be more flexible, we can use the richards model (richards, ) for the cumulative incidence curve. the richards model, also called the power law logistic model, can be written as d dt cðtÞ where ais the parameter that controls the steepness of the curve. note that the logistic model is a special case with a ¼ . its solution is the new cases cðt i Þ in a time period ½t i ; t iþ is also given by ( ). the parameters are q ! ¼ ðr; k; c ; aÞ. to compare the performance of both the sir model and the phenomenological models, we fit these models to the stochastically simulated seir epidemic curve of weekly cases that we introduced in section (fig. ) . we assume that the process error is negligible, and the observations are poisson distributed about the mean that is given by the corresponding models. we use the maximum likelihood method. the results are shown in fig. . the predictions of the exponential model, as discussed before, quickly decreases as more data points are used. both the logistic model and the richards model give robust estimates with fitting windows ending up to the peak of the epidemic. the sir model gives a robust estimate for all fitting windows up to the whole epidemic curve. thus, the sir model is a good model to use to fit the exponential growth rate, even if it may not be the correct mechanistic model. (e.g., it ignores the latent period in this example). it requires more computational power, because the epidemic curve lacks an analytic formula, and needs to be numerically solved from a system of ordinary differential equations. the logistic model and the richards model can be used for all data points up to the peak of the epidemic. fig. also show that the sir model and the logistic model give the narrowest confidence intervals. however, narrower confidence intervals may not be desirable if it has a large chance that it does not contain the true value. due to errors, especially process errors, each realization of the underlying stochastic epidemic process yields a different epidemic curve. these epidemic curves may exhibit different exponential growth rates even if the underlying parameter values are the same. an observed epidemic curve is just a single realization of the epidemic process. does the estimated confidence intervals contain the theoretical exponential growth rate of the epidemic process? this question is answered by the "coverage probability", which is the probability that the confidence interval contains the true value. if the confidence interval properly considers all sources of stochasticity, then the coverage probability should be equal to its confidence level. to illustrate this, we numerically compute the coverage of the confidence intervals by simulating the seir model times and compute confident interval of the exponential growth rate for each realization, and compute the fraction of the confident intervals containing the theoretical value l ¼ : . the results is summarized in below: logistic model richards model coverage probability % % that is, even though the logistic model gives a narrow confidence interval, its coverage probability is low. the coverage probability of the confidence interval given by the richards model is also significantly lower than the confidence level. this is indeed caused by treating process errors as observation errors. if there is under reporting, that is, only a fraction p of the cases can be observed, then the observation error becomes larger as p decreases (i.e., more under reporting). the coverage will become larger as a result. for example, the case fatality ratio of the pandemic influenza is about % (frost, ) . thus, the mortality curve can be treated as the epidemic curve with a large under reporting ratio, and thus the observation error dominates. in this case ignoring the process error is appropriate. ecological models and data in r transmission dynamics of the great influenza pandemic of in geneva, switzerland: assessing the effects of hypothetical interventions statistics of influenza morbidity. with special reference to certain factors in case incidence and case-fatality a general method for numerically simulating the stochastic time evolution of coupled chemical reactions a method to estimate the incidence of communicable diseases under seasonal fluctuations with application to cholera a flexible growth function for empirical use how generation intervals shape the relationship between growth rates and reproductive numbers different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures the comparison of the results of fitting the sir, exponential, logistic, and richards models to a simulated weekly incidence curve, as a function of the end point of the fitting window (upper). the epidemic curve (lower) is shown as a reference. the epidemic curve and the theoretical exponential this research is partially supported by a natural sciences and engineering research council canada discovery grant, and national natural science foundation of china (no. ). key: cord- -b y mybg authors: dellagi, koussay; rollot, olivier; temmam, sarah; salez, nicolas; guernier, vanina; pascalis, hervé; gérardin, patrick; fianu, adrian; lapidus, nathanael; naty, nadège; tortosa, pablo; boussaïd, karim; jaffar-banjee, marie-christine; filleul, laurent; flahault, antoine; carrat, fabrice; favier, francois; de lamballerie, xavier title: pandemic influenza due to ph n / virus: estimation of infection burden in reunion island through a prospective serosurvey, austral winter date: - - journal: plos one doi: . /journal.pone. sha: doc_id: cord_uid: b y mybg background: to date, there is little information that reflects the true extent of spread of the ph n / v influenza pandemic at the community level as infection often results in mild or no clinical symptoms. this study aimed at assessing through a prospective study, the attack rate of ph n / virus in reunion island and risk factors of infection, during the season. methodology/principal findings: a serosurvey was conducted during the austral winter, in the frame of a prospective population study. pairs of sera were collected from individuals belonging to households, during and after passage of the pandemic wave. antibodies to ph n / v were titered using the hemagglutination inhibition assay (hia) with titers ≥ / being considered positive. seroprevalence during the first two weeks of detection of ph n / v in reunion island was . % in people under years of age, . % in adults ( – years) and . % in the elderly (≥ years) (p< . ). baseline corrected cumulative incidence rates, were . %, . % and % in these age groups respectively (p< . ). a significant decline in antibody titers occurred soon after the passage of the epidemic wave. seroconversion rates to ph n / correlated negatively with age: . %, . % and . %, in each age group respectively (p< . ). seroconversion occurred in . % of individuals who were seronegative at inclusion compared to . % in those who were initially seropositive. conclusions: seroincidence of ph n / v infection was three times that estimated from clinical surveillance, indicating that almost two thirds of infections occurring at the community level have escaped medical detection. people under years of age were the most affected group. pre-epidemic titers ≥ / prevented seroconversion and are likely protective against infection. a concern was raised about the long term stability of the antibody responses. in april , the first cases of acute respiratory infections caused by a novel triple-reassortant influenza virus, ph n / v, occurred in mexico and the united states [ ] . the rapid spread of infection to other continents led the world health organization (who) to declare on june that a pandemic of ph n / v influenza was under way, which raised major international concern about the risk of high morbidity and lethality and the potential for severe socio-economic impact. actually, the potential impact of this first third-millenium influenza pandemic has been revisited downwards as morbidity and case-fatality rates were less severe than initially anticipated [ ] . illness surveillance data do not allow to an accurate estimate of the true influenza infection rate, as a substantial proportion of infections are asymptomatic or mild [ ] . serological surveys can overcome this limitation, but must take into account that a significant proportion of the population that exhibited crossprotective antibody titers before circulation of the ph n / v [ ] . this so-called ''baseline immunity'' has to be subtracted from the seroprevalence observed after the pandemic wave, to determine seroincidence in serosurveys [ ] [ ] [ ] [ ] . however, except for few studies [ ] [ ] [ ] , most of these serosurveys did not use serial measurements in the same person, which allows for a better understanding of antibody kinetics and the dynamics of infection within individuals and communities. reunion island ( , inhabitants) is a french overseas department located in the southwestern indian ocean, km east of madagascar and km southwest of mauritius. the first imported case of ph n / v was identified on th july (week ) in a traveller returning from australia. the first case indicating community transmission was detected on st july (week ). ph n / v became the predominant circulating influenza virus within four weeks of its first detection, its activity peaked during week ( ) ( ) ( ) ( ) ( ) ( ) ( ) and ended at week [ ] . contrary to initial fears, the health care system was not overwhelmed, as morbidity and mortality rates were lower than predicted [ ] [ ] [ ] . in order to assess at the community level, the actual magnitude of the ph n / v pandemic and the extent of the herd immunity acquired after passage of the epidemic wave, a prospective population serosurvey was conducted in reunion island during the passage of the epidemic wave in the austral winter season (july-december ): prevalence of infection was assessed on a weekly basis and seroconversion rates were measured using paired sera. the copanflu-run was part of the copanflu international project, a consortium between the french national institute of health and medical research (inserm), the institute of research for development (ird) and the mérieux fondation under the promotion of the school of advanced studies in public health (ehesp). to enable the rapid implementation of the study in anticipation of the imminent spread of the pandemic wave, we used a pre-existing sample of households established in october for the investigation of the chikungunya outbreak (serochik) and updated in may throughout a follow-up telephone survey (telechik) on a basis of households [ , ] . we took special attention to select households representing a wide range of geographic locations in order to minimize the repartition bias. the inclusion phase started on july st (week ) and was continued up to week , throughout the epidemic wave and beyond. a first serum sample (sample ) was obtained from each household member. an active telephonic inquiry was then conducted twice a week to record symptoms compatible with influenza-like illness (ili) occurring in households. report of ili (fever $ . uc associated with any respiratory or systemic symptom) led to three consecutive visits of a nurse to the incident case-dwelling (on day , + and + post-report) to record symptoms and collect nasal swabs from all family members (for qrt-pcr detection of ph n / v. at week , the active inquiry was discontinued and a second (post-epidemic) serum sample (sample ) was obtained (weeks - ) to determine seroconversion rates. sera were aliquoted and stored at uc. the protocol was conducted in accordance with the declaration of helsinki and french law for biomedical research (nu id rcb afssaps: -a - ) and was approved by the local ethics committee (comité de protection des personnes of bordeaux university). every eligible person for participation was asked for giving their written informed consent. viral genome detection by rt-pcr. viral rna was extracted from ml of nasal swab eluate using the qiaamp viral rna kit (qiagen) and processed for detection by taqman qrt-pcr targeting the heamagglutinin ha gene (superscript iii platinum one-step qrt-pcr system, invitrogen) according to the recommendations of the pasteur institute (van der werf s. & enouf v., sop/flua/ ). confirmed ph n / v infection was defined as a positive qrt-pcr detection of the ha gene in at least one nasal swab. hemagglutination inhibition assay (hia). a standard hemagglutination inhibition technique was adapted to detect and quantify ph n / v antibodies [ ] . the antigen was prepared by diluting a non-inactivated cell culture supernatant producing a pdm h n v strain (strain opyflu- isolated from a young patient returning from mexico in early may ) [ ] . briefly, the virus was propagated onto mdck cells under standard conditions. the last passage (used for antigen preparation) was performed in the absence of trypsin and ht-fbs. the supernatant was collected at day seven p.i. clarified by centrifugation at g for min at room temperature, aliquoted and conserved at uc. the hemagglutinating titer of the non inactivated viral antigen was immediately determined under the hia format described below. the dilution providing . hemagglutinating units in a volume of ml was used for subsequent hia. sera were heat-inactivated at uc for min prior to use. sequential twofold dilutions in pbs ( / to / ) in volumes of ml were performed and distributed in v-bottom well microplates. human red blood cells (rbc) were used for hemagglutination experiments. detection and quantification of antibody to ph n / v was performed as follows: ml of virus suspension was added to the serum dilution ( ml) and incubated for hour at room temperature. each well was then filled with ml of a % rbc suspension in pbs (v/v: . %), followed by another min incubation at room temperature. the hia titer was determined as the last dilution providing clear inhibition of hemagglutination. all experiments were performed in the presence of the same negative and positive controls, the latter including sera with / , / , / and / antibody titers. the results reported in this study were based only on serological analysis of paired sera. for the sake of analysis, four successive phases were identified throughout the pandemic wave: phase a (weeks - ) corresponded to early epidemic time, phase b (w - ) to the epidemic unfolding, phase c (w - ) to the immediate post-epidemic stage and phase d (w - ) to the late post-epidemic stage. seropositivity was defined as a hia titer of / or more. the baseline-proxy seroprevalence rate was estimated on serum samples collected in phase a. the cumulative incidence rate of infection measured the raise between the raw seroprevalence rate at any given time during the epidemic phases (s pi) and the age-specific baseline-proxy seroprevalence rate (s pa) (s pi -s pa ). seroconversion was defined as a shift from seronegative at inclusion (sample : hia , / ) to seropositive on follow-up (sample : hia $ / ), or for sera tested seropositive on inclusion as a four-fold increase of hia titers between sample and sample paired sera. we also calculated the proportion of sera that tested seropositive in sample for which the hia titer decreased fourfold and passed under the cut-off value of / in sample . we considered this proportion as a ''seronegation'' rate. the sample size was calculated for identifying risk factors in the prospective cohort study. considering on average three individuals per household, an intra-household correlation of . , a power greater than % could be obtained with a sample size of comprising individuals, assuming exposure levels ranging from % to % and a relative risk greater than . . with , subjects, the study allowed - % absolute precision around the estimated values for seroconversion rates. data entry used epidata version . (the epidata association, odense, denmark). sas version . (sas inc., cary, nc, usa) was used for statistical analysis. the characteristics of the study cohort were compared to those of the population of reunion island and a chi test (or fisher's exact test when non applicable) was used to analyse differences in age, sex and geographic location. cumulative incidence rates of infection (i.e. seroincidence) and seroconversion rates were standardized according to the age structure of the community (french national institute for statistics and economical studies (insee) source). baseline-proxy seroprevalence, cumulative incidence rates of infection, as well as seroconversion and seronegation rates, were expressed as percentages. cumulative reverse distribution curves were used to show the distribution of antibody titers. in all tests, a p value, . was considered significant. we estimated % confidence intervals (cis) of proportions by using a cluster bootstrap technique with re-samples [ ] . after bootstraping, we used an anova model to compare mean cumulative incidence proportions between pandemic phases, within each age group. we used an alternating logistic regression model (alr) with an exchangeable log odds ratio (or) to test the intra-household correlation-adjusted association between factors and the seroconversion outcome. data were analysed with respect to subject age. initially, four age groups were considered: the children and adolescents (, yrs), young adults ( - yrs), middle-age adults ( - yrs), and elderly adults ($ yrs). as the cumulative incidence of infection of the second and third groups were very close, both groups were merged into one adults group ( - yrs). therefore we refer further in our study to three age groups: children and adolescents (, yrs), adults ( - yrs), elderly ($ yrs). a total of , individuals from households were enrolled between weeks and in the copanflu-run cohort, allowing the collection of , sera at inclusion (sample ). during this period, households ( . % of households) containing individuals ( . % of individuals) reported at least one case of ili. sixty subjects among the individuals ( . %, belonging to households [ . %]) were qrt-pcr positive, which documented the ph n / v infection. no positive qrt-pcr could be detected after week and no ili was reported after week , the end of the epidemic wave. the second follow up serum sample (sample ) was obtained for , subjects at least five weeks after the end of the epidemic wave (weeks - ) which allowed the constitution of a serobank of , paired-sera. the profile of the cohort and the major outcomes are displayed in figure . details on inclusions and serum sample timing with respect to the circulation of ph n / v over the island are provided in figure . the socio-demographic and space-time characteristics of the cohort are detailed in table . compared to the community of reunion island, the sample of , individuals for whom pairedsera were available, was older (, yrs: % vs %, and $ yrs: , % vs , %) and composed of a slight excess of females ( . % vs . %). the imbalance was due to a deficit in subjects aged under years, reflecting men at work and the fact that parents declined the second serum for children younger than five. baseline-proxy (,pre-epidemic) hia titers to the ph n / v were measured on sample ( table ) , obtained from subjects ( households) recruited at the very beginning of the investigation during weeks and (phase a, figure ), when the epidemic activity in the cohort was still very low. age distribution in this group was similar to that of the whole cohort (data not shown). the overall, the baseline-proxy seroprevalence rate (hia $ / ), over all ages, was . % ( %ci: . %- . %). however the majority of positive sera had low antibody titers, at the cut off value for confirmation (i.e. = / ). the proportions of sera with hia titer . / were %, . % and . % in the young, middle-aged and older age groups respectively. these results indicate that pre-epidemic baseline antibody cross reactivity was stronger in the elderly ($ yrs) and weaker in children and adolescents (, yrs) and adults ( - yrs), with highly significant differences between age groups (p, . ). the reverse cumulative distribution curves of hia titers are displayed for each age group and for the whole cohort on figure . the proportion of seropositive sera (hi $ / ) steadily increased during the epidemic unfolding (phase b, w - ) and in immediate post epidemic period (phase c, w - ) when it reached its maximum level, then declined in the late post epidemic period (phase d, w - ). this decline was significant enough to return the reverse cumulative distribution curve to baseline levels in the elderly. the cumulative incidence rates, obtained after subtraction of the age-specific baseline-proxy seroprevalence from the raw seroprevalence at each phase of the epidemic are shown in table (note that the cumulative incidence rates of infection represented for the group ''all ages'' were standardized according to age structure of the community). the cumulative incidence rates were much higher in children and adolescents (, yrs), indicating very active transmission of infection within this age group. as mentioned earlier, cumulative incidence rates peaked in phase c (w - ), and then declined indicating some lability of the humoral immune response against the ph n / v. the age-related difference observed in the incidence rates was highly statistically significant (p, . ). to estimate more appropriately the decline of antibody titers occurring after the peak of the humoral response to the ph n / v, we considered paired-sera from the group of subjects for whom the first serum sample (sample ) was obtained just after the epidemic wave (phase c, w - ), and the corresponding second sample was collected at the end of the survey (phase d, w - ). seronegation rates were . % ( / ) for all age groups, . % ( / ) in children and adolescents (, yrs), . % ( / ) in adults ( - yrs) and . % ( / ) in the elderly ($ yrs). differences between the seronegation rates according to age were statistically weakly significant (p = . ). we then considered the individuals for whom paired sera were available and we measured the seroconversion rates according to age and to the time of first serum sample collection (phase a, b or c). criteria of seroconversion were defined in the method section. as shown in table , there was a sharp decline in seroconversion rates across all the age groups, depending on whether participants were enrolled during phase a, phase b, or phase c (p, . ). to interpret these data, one should remember that antibodies at seroprotective levels (hia $ / ), in serum samples collected during the per epidemic phase b or early post epidemic phase c could represent either base line cross reactive antibodies or rising ph n / specific antibodies due to a recent or ongoing infection. this ambiguity could lead to underestimation of the seroconversion rate for subjects enrolled in phases b and c. in order to solve this ambiguity, we specifically considered the group of subjects in whom cross reactive antibodies were detected at the time of phase a (w - ). the seroconversion rate of this group is the most indicative of the exposure of individuals to the whole epidemic wave. it was the highest ( , %, p, . ) in children and adolescents (, yrs), and still significantly high in adults ( . %, p, . ). we then tested in this particular group, the impact of (baseline) pre-epidemic cross reactive antibodies on the rate of seroconversion to ph n / (table ) . no subject with hia titer superior to / had evidence of seroconversion to ph n / . the seroconversion rate in individuals with a hia titer equal to / was linked with age, being more important in children and adolescents (, yrs). the highest seroconversion rate (. %) was registered in subjects with hia titers inferior to / , particularly for the under years where it reached %. hence, the risk of seroconversion decreased when pre-epidemic hia titer was high after controlling for age (p, . ) (figure ) . the multivariate adjusted odds ratio for seroconversion were . ( %ci: . - . , p, . ) per two-fold increase in baseline titer, . ( %ci: . - . , p, . ) per other household members who seroconverted, . ( %ci: . - . , p, . ) figure . the cohort profile and major outcomes. figure details the three phases of the protocol: i) inclusion (weeks - ) and serum samples s collection; ii) follow up for detection of ili in households, qrt-pcr on nasal swabs and estimation of cumulative seroincidence rates; iii) end of the study (weeks - ) and samples s collection. hia on paired sera (s +s ) allowed estimating seroconversion rates. doi: . /journal.pone. .g bp (baseline-proxy) seroprevalence rates were estimated on weeks - in each age group. b cumulative incidence rates measured the raise between raw seroprevalence rates and age-specific baseline-proxy seroprevalence rate. in the group ''all ages'', cumulative incidence rates were standardized according to age structure of the community. doi: . /journal.pone. .t data are numbers, percentages ( % confidence intervals) and alr parameter test p value for comparison of seroconversion proportions according to time of first sample (s ) collection at inclusion, in each age group, after controlling for household selection. in the group ''all ages'', rates of seroconversion were standardized according to age structure of the community. na: not assessed. seroconversion was defined as a shift from seronegative at inclusion (i.e. hia titer , / ) to seropositive on follow-up sample, or as a -fold increase of reciprocal hia titer between first and second paired samples for sera tested seropositive on inclusion (i.e. hia titer $ / ). for age , years (vs age $ years) and . ( %ci: . - . , p = . ) for age - years (vs age $ years). the observed and predicted seroconversion rates according to age and baseline hia titer are displayed figure . finally, we considered the subjects who had been infected by the pandemic virus over the course of the study, verified by a positive qrt-pcr nasal swab, and for whom paired sera were available. initial hia antibody titers in this group were , / , the copanflu-run cohort was set up to conduct a prospective population-based study investigating the herd immunity induced by the pandemic influenza virus and identifying risk factors for ph n / v infection from paired sera collected in an entire community. most works published to date have used either extensive cross-sectional serosurveys on pre-and post-epidemic independent serum samples, the baseline immunity being assessed from stored frozen samples [ , , ] , or non representative adult cohorts (military, health care workers, long-stay patients). antibody titers were measured by hia using a cut-off value set at / as classically recommended. this hia titer at / is considered protective, i.e. conferring % protection against a viral challenge [ ] . our assay has introduced some changes in the experimental protocol compared to the classic one. the use of a non-inactivated viral antigen, i.e. a native virus, with nondenatured epitopes probably allows detection of antibodies to epitopes of the hemagglutinin not detected in the classic hia test. this can induce slight differences in the sensitivity of detection of cross-reacting antibodies, but this does not modify the kinetics of ab and the epidemiological evolution of seroprevalence and does not jeopardize the global comparability of serological results. this is confirmed by the fact that our hi assay detected seroprotective antibody titers in . % and gave evidence seroconversion in . % of qrt-pcr confirmed ph n / influenza, all figures close to those reported in the literature [ , ] . we considered that titers of . / , in sera collected from individuals enrolled during weeks and were cross reactive antibodies and not de novo antibodies triggered by the pandemic virus and hence used them as a proxy for baseline pre epidemic immunity. several arguments support this assumption: i) the first case indicating autochthonous transmission in reunion island was reported by the epidemiological surveillance department of la réunion on st july (week ), i.e. the same day when inclusion started in our study cohort; ii) to days are required to develop an antibody response after viral infection; iii) on weeks and , the epidemic activity due to the pandemic virus was very low in our study cohort and it became significant only after week . hence, during weeks - , households were recruited and only households reported ili cases. nasal swabs collected from these individuals were tested qrt-pcr negative to the pandemic virus whereas one had evidence of coronavirus and rhinovirus using a multiplex rt-pcr to respiratory viruses (h. pascalis, manuscript in preparation). in contrast, during weeks to , individuals belonging to households reported ili, among whom individuals had documented infection by the pandemic virus. our study shows that a substantial proportion of reunion island's population had pre-existing immunity to pandemic influenza virus with the highest baseline-proxy seroprevalence rate observed among adults aged of years or more. other studies from all continents had also reported high pre-epidemic seropositivity rates among the elderly [ , , , [ ] [ ] [ ] [ ] [ ] , though large variations do exist between countries [ , , , , ] . these cross reactive antibodies have been interpreted as being the residual signature of the remote exposure of these individuals to h n viruses circulating before [ , , , ] . baseline seropositivity rates that we report in children and in younger adults (i.e. %- %) were notably higher than those reported from other parts of the world [ , , , , [ ] [ ] [ ] . however one should note that these baseline antibodies were of low titer, just at the level of the hia threshold (i.e. / ). several factors could have contributed to this comparatively high baseline rates found in our study: i) it may reflect the fact that the hi test used in our study was marginally more sensitive than the classic one [ ] ; ii) some individuals may have already been infected with ph n / virus at weeks and and may have triggered an antibody response to the virus. this hypothesis seems unlikely in view of the arguments presented above and of a similar high proportion of sera titering hia = / among sera from adult patients sent for diagnostic purposes to the regional hospital microbiology laboratory, during the first half of (i.e. before the pandemic) (data not shown). however we cannot formally exclude this hypothesis in view of a recently reported study from taiwan [ ] that showed evidence of subclinical community transmission with proved seroconversion several weeks before report of the first documented case in the island. a similar conclusion was also drawn from australia [ ] ; iii) our serological test might detect cross-reactive antibodies triggered by recent vaccination with trivalent seasonal influenza vaccine as reported [ , [ ] [ ] [ ] [ ] [ ] . however, seasonal influenza vaccines were of rather limited use in reunion island, especially in children and young adults; iv) finally the high baseline titers may reflect the infectious history of the individuals to seasonal influenza viruses cross antigenic with ph n / virus as recently suggested for seasonal h n infection [ ] . this serosurvey indicates that a large fraction of the reunion island population was infected with the pandemic virus. younger people, have paid the main tribute to the epidemic as almost two thirds show evidence of seroconversion, confirming earlier clinical reports from the island [ ] and accumulating reports from other countries [ , , , ] and suggesting that school children have likely played the central role in the epidemic diffusion of the pandemic virus. lower infection rates were found in adults and the lowest rates were recorded in the elderly. based on clinical cases reported to the epidemiological surveillance services [ ] , it was estimated that , persons in reunion island who consulted a physician were infected by the ph n / virus during the weeks of the epidemic, giving a cumulative attack rate of . %. taking into account those who did not consult a physician, the number of symptomatic infected persons was estimated to , (attack rate: . %). in fact, the attack rate of ph n / infection in our serosurvey was about %- % at the peak of the antibody response (i.e., weeks - ), a figure which is at least to times higher than rates of infection based on clinical cases the wide gap between the two estimates indicates that a large fraction (almost two thirds) of those who got infected by ph n / virus escaped medical detection, probably because they developed mild disease or asymptomatic infection, a further indication of the benign nature of the virus, at least at the community level. in england, baguelin et al. [ ] estimated that the cumulative incidence rates of infection by the pandemic virus in children were to times higher than that estimated from clinical surveillance. our study, as others [ ] , indicates that pre-existing cross reactive antibodies to ph n / at titers $ / prevented from seroconversion in response to the pandemic virus. this level of pre-existing cross reactive immunity likely confers true protection against infection as about two thirds and one third of documented infection (qrt-pcr positive) in our series have occurred in individuals with baseline hia titers , / and = / respectively and less than % of documented infections occurred in individuals with base line titers . / . the protection was effective not only in older adults but also in younger persons. this indicates that protection was conferred not only by baseline cross reactive antibodies triggered by close ph n / viruses that circulated before (as in the elderly), but also by antibodies likely resulting from recent exposure to seasonal influenza epidemics (as shown in younger persons) [ ] . the observed seroconversion rates depend on age, after adjusting for baseline ph n / titers. the protective role of increasing age might be explained by a stronger cross-immunity in adults and elderly or by a higher exposure of young subjects to the virus during the epidemic (due to social contacts and mixing patterns). it may also indicate that immune mechanisms other than cross reactive antibodies detected by hia (i.e. immunity to neuraminidase and conserved t cells epitopes [ ] might develop throughout life, providing additional protection from infection or severe disease, especially in the elderly. interestingly, evidence is seen for a decline in antibody titers, which occurred soon after the passage of the epidemic wave. in paired sera, this decline was significant enough to bring, within a few weeks, almost % of sera that tested positive (i.e. hi titers $ / ) in the immediate post epidemic phase to levels under the cut-off value in the second serum sample. this decay accounts for the observation that older adults ($ yrs) in the study cohort were apparently almost completely spared by the epidemic if one only considers cumulative incidence rates derived from iha titration on samples (weeks - ). in fact, the cumulative incidence rate in older adults measured just after the epidemic peak (i.e. weeks - ) was . %. similar results of early antibody decay were recently reported [ , ] . more generally, these data show that serosurveys conducted months after passage of the epidemic, likely underestimate the real extent of ph n / infection, compared to antibody titration performed earlier, when humoral responses are at their highest level. whether the decline in antibody titers has functional immunologic consequence to individuals or within the communities warrants further investigation. however, one should note that there was no second epidemic wave in reunion island during the subsequent austral winter seasons in and . influenza during the winter was at a level not higher than the usual passages of seasonal flu, though almost two thirds of documented cases in were also due to ph n / v [ ] . in addition many fewer pandemic virus isolates were noted during the ongoing austral winter, strongly suggesting that the first epidemic wave had conferred a solid herd immunity, at the community level. our study has some limitations. the fact that the epidemic progression coincided with the implementation of the prospective study, we were not able to collect, strictly speaking, pre-epidemic sera from the cohort members. therefore we used as proxy base line seroprevalence data from individuals recruited at the very beginning of the investigation when the epidemic activity in the cohort was very low. this may overestimate the base line immunity if subclinical community transmission had occurred before the first cases of ph n / influenza were reported. antibodies to the pandemic virus were detected by hia, a test that has a good specificity but a rather low sensitivity [ ] . hence, the threshold of / may underestimate the number of infected individuals. however, rates of seroconversion, the serologic gold standard test based on paired sera, likely gave the most accurate picture of the pandemic in at the community level in reunion island. emergence of a novel swine-origin influenza a (h n ) virus in humans comparative epidemiology of pandemic and seasonal influenza a in households how to maintain surveillance for novel influenza a h n when there are too many cases to count cross-reactive antibody responses to the pandemic h n influenza virus incidence of pandemic influenza a h n infection in england: a crosssectional serological study influenza a(h n ) seroconversion rates and risk factors among district adult cohorts in singapore seroprevalence following the second wave of pandemic risk factors and immunity in a nationally representative population 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virus in infected patients and vaccinated people in china surveillance de la grippe à la réunion we acknowledge the nurses, investigators and technicians of the cic-ec de la réunion. key: cord- - blol to authors: karadag, engin title: increase in covid‐ cases and case‐fatality and case‐recovery rates in europe: a cross‐temporal meta‐analysis date: - - journal: j med virol doi: . /jmv. sha: doc_id: cord_uid: blol to the new coronavirus (covid‐ ) infection reported in china in december has become a pandemic in a few weeks, affecting the entire world. in this respect, it is crucial to determine the case‐increase, case‐fatality, and case‐recovery rates to control covid‐ . in this study, the case‐increase, case‐fatality, and case‐recovery rates of covid‐ in european countries were analyzed with the meta‐analysis method using data released by the health organizations and who. the data were obtained from the website of health organizations of european countries and the website of who until may . the analyses were carried out on covid‐ ‐diagnosed cases in european countries. the case‐increase, case‐fatality and case‐recovery rates of covid‐ were calculated using % confidence intervals ( % ci), single‐arm meta‐analysis, cross‐temporal meta‐analysis, and meta‐regression random‐effects model. the standardized case‐increase rate of covid‐ is % ( % ci [ . , . ]) and the average case‐increase rate in european countries has started to decline by around % ( % ci [ . , . ]) weekly. the countries with the highest rate of case increase are belgium, sweden, russia, the netherlands and the united kingdom. although the case‐fatality rate of covid‐ patients was . % as of may ( % ci [ . ‐ . ]), this rate is . % ( % ci [ . , . ]) in standardized time ( th week). the case‐recovery rates of patients are % ( % ci [ . ‐ . ]). this study presents important results regarding the covid‐ pandemic in europe. although the rate of increase in new covid‐ cases has dropped, there is not much decline in the case‐fatality rates and no increase in case‐recovery rates. the case‐fatality rate of covid‐ in europe was estimated to be in the range of % to . % and a minimum of weeks (as of may) is expected to have the figure below % in a country with an average case‐increase rate. monitoring case fatalities in belgium, the netherlands and sweden, and treatment successes in germany and austria play a role of utmost importance. italy have taken the second and third places in the world with the most number of covid- cases. these countries have also a very high case-fatality rate. it has been assumed that the virus has been circulating within the european population since january based on the number of cases and the advanced stage of the disease. estimating the rates of case increase, case fatality, and case recovery are key parameters for understanding the basic epidemiological characteristics of the pandemic. although several studies have been conducted to determine the case-increase, case-fatality, and case-recovery rates at various stages of the outbreak, studies involving reliable rates of case increase, case fatality, and case recovery on the basis of metaanalysis in the european specific for covid- are limited. , the available evidence on the contagiousness, case fatality, and case recovery of covid- is focused on china. , in initial studies, the case-fatality rates were reported as %. however, this figure was calculated with a small group of inpatients. afterward, as more data found, the case-fatality rate dropped to . % and to . % and then to . %. serious attention has not been paid to these basic epidemiological characteristics in europe, and considering the rapid increase in covid- in europe, it is of paramount importance to understand the rate of the case increase, case fatality and case recovery in europe to guide the applications of prior prevention and control measures. therefore, the epidemiological characteristics, case-increase, casefatality, and case-recovery rate of covid- in europe using the data of a -month period from january until today were found using the method of meta-analysis. data were analyzed using microsoft excel and comprehensive meta-analysis . ® . the health organizations of european countries and who conducted a comprehensive systematic literature review in their online databases on may to provide the data required for meta-analysis. the search terms are covid- ; -ncov; the number of daily cases, deaths, and discharges. in addition, laboratory-approved covid- cases were included in the analyses to guarantee the comprehensiveness and accuracy of the research. all search results were evaluated ( figure ) according to the preferred reporting items for systematic reviews and meta-analyses (prisma) and the final analysis was conducted on covid- diagnosed cases in countries. to minimize the potential for biases such as sampling or measurement bias in undertaking a meta-analysis study, rigorous methods should be used to locate, select, and aggregate the results of individual studies. incorporating an assessment of the risk of bias of these studies is essential in interpreting their results and may help to avoid underestimating or overestimating the parameter of interest. in this study, ahrq's guidance on constructs to include or exclude from risk-of-bias assessment was taken into account in evaluating the risk of bias. as the country dataset was used instead of research data, the guideline was adapted according to the study. therefore, the risk of bias of each country's data included in this study were evaluated as follows: ▪ in terms of the risk of precision, the laboratory-confirmed covid- cases, deaths, and recovered cases in each country were taken into account. the cases which were not laboratory-confirmed were excluded. ▪ the number of cases, deaths, and recoveries announced by the health organizations of the countries were confirmed by data from who and other health institutions. unconfirmed data were excluded from the analysis because of the risk of biased, bad, or inadequate reporting. ▪ a standard calendar has been created for covid- cases, deaths, and recovered cases in countries for applicability risk (see section . for details). ▪ publication bias was assessed using the funnel chart and the trim and fill test. no evidence of bias was observed in the data included in the meta-analysis according to funnel graphs. in addition, there was no difference between the size of the effects observed in the trim and fill test conducted according to % ci in the random-effects model and the size of the virtual effects generated according to the randomeffects model to correct the effects caused by bias. there are different methods to calculate the case-increase rate. however, as the covid- outbreak only has a -month period, the rate of new cases diagnosed daily in this study was calculated as the ratio ofthe new cases to the total number of cases. the first covid- cases were not detected on the same date in the european countries and the rate of new cases/total cases was very high in the first days of the pandemic, therefore, the analyses were standardized as day on the th day in all countries. in addition, case rate analyses were standardized by population, as the populations of case countries were not similar. the weighted average of the case-increase rate calculated for each day of the week was used for the case-increase rate of each week. the case-fatality rate was determined as the ratio of those who died from covid- disease to the patients with covid- . in calculating weekly case-fatality rates, the average of fatality rates calculated for each day of that week was used for the fatality | karadag rate of each week, starting from the day following the first death. the use of epidemiological velocity terms interchangeably in the literature has become a common nomenclature error. therefore, the fatality rate should not be confused with the mortality rate. a mortality rate-often confused with a case-fatality rate-is a measure of the number of deaths (in general, or due to a specific cause) in a population scaled to the size of that population per unit of time. a case-fatality rate, in contrast, is the number of dead among the number of diagnosed cases. the case-recovery rate was determined as the ratio of the number of patients recovering with the diagnosis of covid- disease. in the calculation of the case-recovery rates, the day of the th incident was accepted as the th day and calculated as the ratio of the total number of case recovery to the relevant day for the case-recovery rate on the st, th, th, nd, th and th days. meta-analyses were carried using microsoft excel and comprehensive meta-analysis . ® software. heterogeneity between the studies was tested using the cochran χ test and i , when i was below %, a stabilization model was used. when i was over %, a random effect model was selected. the combined case-increase rate and % confidence intervals ( % ci) single-arm meta-analysis and the cross-temporal meta-analysis random-effects model (weighting, case sizes of each country were taken into account) weighted effect size were calculated. to investigate the heterogeneity, the percentage of population the over -year-olds, and the population growth rate to the rate of increase in cases, the rate of case fatality and case recovery were tested using the meta-regression random-effects model. p < . was considered statistically significant. the study examined the increase of covid- cases in european countries using cross-temporal meta-analysis. therefore, analyses were standardized to the th day, on which the case was spotted, as the zeroth day. the reason for starting the analyses from the th case is that the increase rate below cases is very high due to the small numbers. in addition, case increase analyses have been standardized by the population due to the fact that the populations of case countries are not similar. in addition, the meta-regression analysis shows no statistically significant effect of the population rate above -year-olds on average case-increase rates (p > . ). considering the day on which the th case was seen as the zeroth day, the weekly case-growth rate, increase difference, standard deviations, and effect size (es) were used to define d and r of the difference. ( ) firstweek secondweek ( ) considering the day, on which the first case-fatality was seen as the zeroth day, the weekly case-fatality rate, case-increase difference, standard deviations, and effect size (es) were used to define d and r of the difference (equations and ) . the case-fatality rate in europe was found to be % higher in the second week (d = . , r = . ) compared to the first week. the case-fatality rate was . % higher in the third week compared to the previous week (d = . , r = . ) and the case-fatality rate was . % higher in the fourth week compared to the previous week (d = −. , r = . ). the daily case-fatality rate was . % higher in the fifth week (d = − . , r = . ) compared to that of the fourth week (table ). in the meta-regression analysis, no statistically significant effect was found in countries with the population rate of the above -year-olds and the population density on the case-recovery rates (p > . ). considering the day, on which the th case was seen as the zeroth day, the weekly case-growth rate increase difference, standard table ). this meta-analysis includes laboratory-approved case data obtained between january and may to analyze the epidemiological characteristics of covid- in europe. this study, covering european countries and cases, reflects the latest data since the emergence of covid- . the results showed relatively low heterogeneity in terms of single-arm meta-analysis. the sensitivity analysis also showed that the results were not affected by countries' data and that there was no bias. furthermore, meta-analyses of randomized controlled data were not found to be superior to nonrandomized data in terms of evidence level. the cases included in the analysis were between january and may. the meta-analysis based on the random effect model showed that covid- had a case-increase rate of %. it was also noted that the discharge rate of patients was %, and the casefatality rate was %. the results of the cross-temporal meta-analysis in europe showed a decline in the case-increase rate of cases. a country with a european average case-increase rate was estimated to have a minimum of weeks (as of may) to experience a decline below %. there is not much variation in weekly case-fatality rates at covid- according to the results of a cross-temporal meta-analysis. the analysis estimated that the case-fatality rate of covid- in europe would range between % and . %. the case-fatality rate of sars-cov, which was a similar outbreak, was %, while the casefatality rate of mers-cov was over %. , in contrast to the two viruses, covid- has a lower case-fatality rate. according to the clinical trials, it has been observed that the elderly (> years) were reported to be in the majority of deceased patients in conclusion, while there is a negative trend in the increased rate of cases in european countries, differences in population characteristics, treatment methods and health infrastructure affect case-fatality and case-recovery rates. even though the first months of the pandemic has ended, the case-recovery rate of patients is relatively low. although the clinical effect of some drugs has been discussed in recent days, it has been reported that plasma therapy had a definite healing effect for survivors, especially in severe, cases. this indicates that countries having a case increase in the number of patients recovering with plasma treatment will recover faster from the pandemic. in addition, while italy, spain, and the united kingdom are more involved in the number of deaths in research, reports and other studies, belgium, the netherlands, and sweden, where case-increase and case-fatality rates are high and the rate of case-recovering patients is relatively low, should be followed carefully. some limitations of the study should be taken into consideration. first of all, our results are limited to the early term of the pandemic on a country basis. in addition, a country is an extremely rough unit of analysis. also, the number of confirmed cases may be biased for various factors, whereas these factors were probably stable in our case over a short period of time when they were analyzed. engin karadag http://orcid.org/ - - - monitoring transmissibility and mortality of covid- in europe clinical features of patients infected with novel coronavirus in wuhan coronavirus disease (covid- ) in italy case-fatality rate and characteristics of patients dying in relation to covid- in italy different epidemic curves for severe acute respiratory syndrome reveal similar impacts of control measures nowcasting and forecasting the potential domestic and international spread of the -ncov outbreak originating in wuhan, china: a modelling study imperial college london mrc centre for global infectious disease analysis. news/wuhan coronavirus the reproductive number of covid- is higher compared to sars coronavirus covid- patients' clinical characteristics, discharge rate,and fatality rate of meta-analysis assessing risk of bias in prevalence studies: modification of an existing tool and evidence of interrater agreement assessing the risk of bias of individual studies in systematic reviews of health care interventions. agency for healthcare research and quality methods guide for comparative effectiveness reviews trim and fill: a simple funnel-plot-based method of testing and adjusting for publication bias in meta-analysis a dictionary of epidemiology epidemiology in medicine meta-analysis of well-designed nonrandomized comparative studies of surgical procedures is as good as randomized controlled trials from sars to mers, thrusting coronaviruses into the spotlight sars and other coronaviruses as causes of pneumonia clinical features of three avian influenza h n virus-infected patients in shanghai clinical characteristics of novel coronavirus cases in tertiary hospitals in hubei province covid- in colombia endpoints. are we different, like national health commission of the people's republic of china's main website how to cite this article: karadag e. increase in covid- cases and case-fatality and case-recovery rates in europe: a cross-temporal meta-analysis key: cord- - qhdq authors: sirÉn, anders; hambÄck, peter; machoa, josÉ title: including spatial heterogeneity and animal dispersal when evaluating hunting: a model analysis and an empirical assessment in an amazonian community date: - - journal: conserv biol doi: . /j. - . . .x sha: doc_id: cord_uid: qhdq abstract: hunting in tropical forests is typically most intense near human settlements, and this creates gradients of decreasing animal densities toward those settlements. within the context of this spatial pattern, we evaluated the status of game in the hunting grounds of an indigenous community in eastern ecuador. we constructed a spatially explicit model of hunter‐prey interactions that mimicked the hunting in the village and included realistic animal‐dispersal rules. we compared predictions from the model with distributions of animal harvest rates and catch per unit effort of game species. six species were overharvested in part or all of the area, and two other species were probably being overharvested, although high dispersal rates complicated the interpretation. we then compared our method with methods that have been used previously. we argue that because our method provides information about the spatial extent of overharvesting, it could be particularly useful in informing decision makers about where to establish no‐take areas and could therefore aid in improving the sustainability of hunting in tropical forests. wild game is an important source of food and income for the inhabitants of rural amazonia and other tropical rainforests (redford ) . game species also perform important functions as herbivores, seed predators, and seed dispersers, and the absence of these animals could lead to significant ecological chain effects (e.g., redford ; fragoso & huffman ; roldán & simonetti ) . for both reasons, it is problematic that game populations in tropical rainforests are being overharvested (redford ; robinson & bennett ) . adjusting harvest levels based on the productivity of each game species requires understanding how different harvest levels affect game populations. in that respect, two important models have been constructed. first, robinson and redford ( ) calculated maximum sustainable yield (msy) for amazonian game mammals, based on species-specific estimates of carrying capacity and intrinsic rate of natural increase (see also slade et al. ). the msys are then compared with observed harvest rates to evaluate whether these rates are sustainable. the model has been used for evaluating the sustainability of hunting in tropical forests of south america (alvard et al. ; hill & pawde ; mena et al. ) and africa (fa et al. ; fitzgibbon et al. ; muchaal & ngandjui ) . second, bodmer ( ; see also robinson & bodmer ; bodmer et al. ; townsend ) elaborated a model based on population-specific birth rates and densities to calculate production values for comparison with harvest rates. a practical problem with this method is that it requires the use of labor-intensive line transects to calculate population density. milner-gulland and akçakaya ( ) evaluated how current methods for evaluating sustainability of hunting in tropical forests performed under conditions of uncertainty, bias in parameter estimation, and habitat loss and concluded that current methods are prone to overestimate the sustainable level of harvest. these authors also point out that current methods do not incorporate spatial heterogeneity. hunting effort in tropical forests is typically highest near human settlements. therefore, densities of major game species tend to decrease with distance from settlements (robinson & bennett ; peres & lake ) . moreover, townsend ( ) , begazo and bodmer ( ) , and novaro et al. ( ) suggest that many areas function as source-sink systems, where remote areas with low hunting pressure produce a surplus of animals that disperse to areas closer to settlements, where they are hunted. thus, to understand the dynamics of the interactions between hunters and game populations, it is necessary to take into account two separate spatial phenomena: ( ) uneven distribution of hunting effort, which tends to create gradients in animal densities and ( ) animal dispersal, which tends to smooth out these gradients. the approach we used is different from that of previous models. instead of asking how much can be sus-tainably harvested, we asked where production can be increased. we believe that this question is relevant to the management of amazonian wildlife because, for instance, no-take areas have been proposed by scientists as promising management tools in situations with a high level of uncertainty (e.g., quinn et al. ; mosquera et al. ; milner-gulland & akçakaya ; lockwood et al. ) . specifically, we show that hunting effort, harvest rate, and catch per unit of effort (cpue) varied over the hunting territory of an amazonian community. we then used this spatial gradient of hunting effort as a quasi-experimental setting and, for each species, made a preliminary assessment of the spatial extent of overharvest, where overharvest means that animal density is reduced to a point where its full productive potential is not realized. finally, we developed a spatially explicit model to evaluate how animal dispersal affects observed spatial patterns of harvest rates and cpue. our study area was in the quichua community of sarayacu ( • s, • w), situated in roadless land along the bobonaza river in eastern ecuador. the community consisted of five clustered hamlets ( fig. ) of households and inhabitants. the area was dominated by old-growth tropical rainforest, except next to the settlement (table ) . the elevation was - m above sea level, and local people recognized two dominant forest types, plain forest and hill forest, which were fairly evenly distributed over the area. for most terrestrial animals, the area was fairly homogenous in terms of habitat quality, an important assumption underlying the methods we used for interpreting our field data. hunting and fishing were the most important sources of animal protein for local people. shotguns were the dominant hunting weapons, although occasionally spears, blowguns, machetes, or stones were used. most hunting was done by walking, sometimes with a dog, through the forest in the daytime. at night, hunters with torchlights followed waterways. hunters also waited for animals at fallen fruit or at bait they had set, for instance when hunting large rodents and armadillos and occasionally when hunting deer and tapir. to hunt birds that sing at night, hunters first located the tree where the bird was singing and then waited there until dawn to shoot it. we recorded hunting kills of over species, but we limited our analysis to the most preferred game species (table ) . volunteer community members reported on hunting activities. primarily, we used the household as our sampling unit because this provided a sample of both frequent and figure . settlements, areas used for data collection, and hunting-effort zones. the darker the shading, the greater the hunting effort. the heavy black line delimits the area we assumed to be hunted exclusively by people from sarayacu. for the areas outside this line, we assumed that hunters from sarayacu hunted only half the area and that hunters from other communities hunted the other half. (map source data: instituto geográfico militar : , , arcworld supplement, environmental systems research institute.) occasional hunters. random sampling was not an option because some people initially regarded the project with suspicion and could have misinterpreted a random selection of their households as an attempt of coercion. avoiding such potential sources of conflict was particularly important because the fieldwork coincided with a period of extreme social tension related to planned oil-prospecting activities in the area. therefore, because sampling was based on voluntary participation, we could have a skewed sample. to control for this possibility, we asked key informants from each hamlet to group the households into four categories according to their level of hunting activity: ( ) do not hunt, ( ) hunt little, ( ) hunt much nearby, or ( ) hunt much far away. this grouping showed that households of all categories, except that of do not hunt, were fairly equally represented among participants. excluding the households that do not hunt, households remained. out of these, households ( %) participated in the study. we are therefore confident that the participating households constitute a representative sample of the community. at the start of the study, participating households received a form for reporting their hunting activities. one person, usually the most active hunter in the household, recorded his own hunting activities and those of other household members. after months of data collection, we recruited field assistants in each hamlet to collect data. most assistants had previously been in charge of reporting hunting activities from their own household and were selected because they had shown particular skills and interest in the study. the assistants were - years old and had primary or secondary schooling. they were also employed in other research activities, and various training events were arranged to increase their skill. on a rotational basis, a.s. and j.m. accompanied the assistants to supervise their work. occasionally, assistants switched robinson & redford ; , strier ; , c.a. peres , quoted in reference ; , d.p.r stevenson , quoted in reference ; , defler ; , peres ; , bezago & bodmer ; , fragoso ; , beck-king & beck-king ; , judas & henry ; , barrientos-segundo & maffei ; , mena ; , peres ; , santamaria & franco ; , herrera & taber ; , medici et al. ; , palacios & rodriguez ; , suarez . j based on observations of a tagged, free-ranging, semiwild tapir in our study area. conservation biology volume , no. , october duties, collecting data forms in hamlets other than their own. one side of the form featured a map of the community territory and its surroundings divided into areas, each with a unique number, that were similar in size and had limits represented by well-defined terrain features. out of these areas, we excluded from the analysis because interviews with key informants showed that these were principally used by hunters from neighboring communities. on the map, hunters drew the trajectories traveled while hunting and marked with a cross places where they used sit-and-wait hunting methods. later, we measured trajectories with a ruler in order to use the trajectory length as a measure of hunting effort in each area. the other side of the form contained drawings of game animals, with the local name and columns for indicating the area number, hunting method (according to categories indicated in table ), and habitat. the drawings made it possible for illiterate people to indicate the number of animals hunted by putting crosses next to the animal. when collecting the forms, about every weeks, we performed detailed interviews to double-check and complement the recorded information. because of an annual hunting festival and adjustments in the sampling regime half-way through the study, we had three data sets: nonfestival, festival, and large animals. the nonfestival data set was collected from may to july and includes all regular hunting activities by the participating households. during this period, participating households in hamlets changed about every months, usually in connection to hamlet workshops, where we presented results and treated issues related to the project. the sample was geographically stratified because the number of participating households from each hamlet was roughly proportional to the total number of households in the hamlet. similarly, during school vacations, when households move to secondary homes to enjoy better hunting and fishing, households were grouped into eight geographical zones. the number of households in the sample increased with time from to . to avoid bias due to variation in sample size between seasons, we applied month-specific weighting factors when converting the harvest data to an estimate of annual harvest in each area. prior to the hunting festival, groups of hunters belonging to three festival houses spend about a week going to the remotest corners of the community territory to hunt huge amounts of game. so we collected data at the individual rather than household level during festival time. out of festival hunters, reported their hunting activities, providing a weighting factor of . for estimating annual harvest rates for festival hunting. at the same time we collected the festival data, recording of hunting activities not directly related to the festival continued as usual. to estimate total annual harvest, we added annual harvest rates from the two data sets, festival and nonfestival. after year of data collection, we had sufficient data on hunting effort and harvest of most small species but insufficient data for larger species. therefore, from april to april , we collected data on large animals by using a simplified form featuring all species except a. paca, d. fuliginosa, and n. urumutum and asking for data only on harvest and not on hunting effort. we assumed our results on hunting effort from the first year could be extrapolated to the following year. the sample size for this data set was - households but varied between hamlets, such that we applied hamlet-specific weighting factors when calculating annual harvest rates. for species not included in the large-animal data set, all calculations were based only on the nonfestival and festival data sets, which included data from householdparticipation days (the sum of the number of days each household participated) and , km walked by hunters. for the species included in the large-animal data set, the annual harvest was calculated as a weighted (according to the number of household participation days) average of one estimate based on the nonfestival and festival data sets and another estimate based on the largeanimal data set. together, this included data from , household-participation days and approximately , km walked by hunters. because the majority of recorded hunting kills were made when hunters were walking (table ) , we used the kilometers walked per square kilometer per year as a measure of hunting effort in each area. other researchers have used time rather than distance as a measure of hunting effort in tropical forests (e.g., vickers ; de souza-mezurek et al. ) , but this was not possible because of the high spatial resolution of our data collection. to aggregate the areas into hunting effort zones, we first smoothed the hunting effort with geographic information system software. we converted the map into a grid of cells of × m, in which each cell was assigned the average hunting effort of all cells within the surrounding × km square. we calculated the smoothed value for each area as the average value for all cells within the area. finally, areas were grouped into seven zones according to hunting effort: zone had the lowest hunting effort and zone the highest (fig. ) . hunting effort for each zone was calculated by summing the original (unsmoothed) values for all the areas within a zone and dividing by the total area of the zone. harvest rates were calculated as annual harvest in a zone divided by its area in square kilometers. catch per unit effort (cpue) was calculated as the number of killed individuals in a zone divided by hunting effort. we used cpue as a proxy for population density, as is commonly done in studies of fish (e.g., salthaug & godø ; marchal et al. ) and occasionally in studies of game mammals (novak et al. ; lancia et al. ) . using cpue as a proxy for density rests on the assumption that an animal encounter always leads to a hunting attempt, which is fairly reasonable for the species we examined. for a. paca, d. fuliginosa, n. urumutum, and m. salvini, which were frequently hunted using sit-and-wait methods, only hunting kills achieved when walking were included in the calculations of cpue. for other species, particularly mazama spp., t. terrestris, and m. salvini, even when these species had been hunted with sit-and-wait methods, the actual encounter (finding tracks or hearing song) occurred while walking. therefore, all hunting kills of these species, regardless of method, were included in the calculations of cpue. for each species, we examined harvest rate as a function of hunting effort and cpue as a function of effort. to interpret these data, we performed linear regressions on harvest rate versus hunting effort and on ln(cpue) versus ln(hunting effort). the log transformation in the latter regression was used because of the obvious nonlinearity in the data. a decreasing harvest rate with increasing hunting effort indicates overharvest because the local population is reduced below the density that yields maximum production. also, decreasing cpue with increasing hunting effort indicates that hunting reduces population densities, and, when this decrease is substantial, it may indicate overharvesting. to determine whether observed patterns could be affected by animal dispersal, we developed a spatially explicit model of hunter-prey interactions that mimicked the hunting practices in the village. with this model, we evaluated the role of animal dispersal and total hunting intensities on the spatial distribution of cpue and harvest rates. we used a standard, discrete-time population model ( yodzis ) to which we added spatial structure (for a similar continuous-time model, see quinn et al. ) . spatial structure was introduced by separating the area into patches that were linearly connected (results are independent of the number of patches and the specific location of patches relative to each other). within each patch, population dynamics depended on the local reproduction, the number of animals killed, and the number of animals migrating to and from the patch. mathematically, the different processes were entered sequentially into the model, and the dynamics of individuals (n) in patch i from time t to t + were then described as where e i is the emigration probability from patch i, h i is the proportion killed in patch i, r i (n i,t ) is the densitydependent reproductive rate, and the last term is the sum of immigration from other patches. to make the model specific to the problem, we made the following additional assumptions: ( ) prey birth rates figure . spatial distribution of hunting effort in the sarayacu community. the x-axis represents the mean distance of each hunting-effort zone from the center of the community if the hunting-effort zones were organized as concentric rings (compare with fig. were density-dependent as a logistic growth function; ( ) hunting effort was normally distributed, with the highest effort at the village in the center (fig. ) ; and ( ) most dispersal was local, with a smaller number of long-range dispersers, as is known for both mammals and birds (waser ; turchin ) . we assumed that the redistribution of individuals followed a gaussian distribution similar to dispersal functions used in fisheries management models (quinn et al. ; lockwood et al. ) . we introduced these assumptions into eq. in the following way. first, local birth rates were assumed to depend on local density according to a standard logistic growth function, where r is the maximum number of offspring per individual, k is the maximum number of individuals per patch, and β is a parameter describing the shape of the density dependence. second, local hunting effort (h) was modeled as a gaussian distribution, where h max is the hunting intensity at the area center, s is the standard deviation of the distribution in hunting intensity, z is the distance from the village, and a is a parameter describing the probability of discovering and killing an animal in the patch. assuming a standard type i functional response (yodzis ) , local hunting effort was transformed to the proportion of surviving animals (s i ) as third, we assumed that the redistribution of animals followed a gaussian distribution, where e is the probability of dispersing x distance units from the previous position and d is a space-independent dispersal rate. dispersal here means the redistribution of individuals over time (sensu turchin ) and does not necessarily correspond to speed of movement or similar physical measures. when calculating the redistribution, we assumed that there was no net migration across area borders. we started each simulation with animal densities at carrying capacity and ran it time units, at which point the total number and the distribution had stabilized. through simulations, we explored a range of hunting intensities (h max = . - ), animal dispersal rates (d = - ), and maximum birth rates (r = . - . ), while keeping the remaining parameters fixed (k = , β = . , s = ). hunting effort was times higher in the central area (zone ) than in the most remote area (zone ), and the distribution of hunting effort in space approximately followed a gaussian distribution (fig. ) . according to the results of the regression analysis, we divided the species into four groups, representing different degrees of overharvesting. group (l. lagotricha) was the most overharvested ( fig. a & b) . there was a negative correlation between harvest and hunting effort and a negative correlation between cpue and hunting effort. group species (t. tajacu, t. terrestris, m. salvini, n. urumutum, and m. gouazoubira) (fig. c-l) showed signs of overharvesting but to a smaller degree than group species. similar to group , there was a negative correlation between cpue and hunting effort, but there was no correlation between harvest rate and hunting effort. instead, harvest rate peaked at an intermediate hunting effort. the sharp decrease in cpue values therefore occurred at higher hunting efforts for the group species than for the group species, indicating that populations in the zones of low hunting intensity may be less reduced by hunting. group species (m. americana, t. pecari, and a. seniculus) showed ambiguous results. similar to group and , cpue and hunting effort were negatively correlated for m. americana (fig. m) , but there was also a positive correlation between harvest rate and effort (fig. n) . t. pecari and a. seniculus showed no correlation for either regression (fig. o-r) . the lack of correlation between cpue and hunting effort may mean that species are not being overharvested, whereas the lack of correlation between harvest rate and hunting effort may indicate overharvesting. hunters often killed several individuals of these species at the same time, however, so the results are sensitive to single hunting events. group iv species (a. paca, d. fuliginosa, and a. belzebuth; showed no indications of overharvesting. harvest rate and hunting effort were positively correlated, and there was no correlation between cpue and hunting effort. for those species showing signs of overharvesting (groups and ), we visually examined where each species was overharvested based on the criterion that cpue should be considerably less than % of the maximum cpue (see robinson & redford ) . according to this criterion, all group species are overharvested in zones and and in some cases also in zones and (t. tajacu and t. terrestris), whereas l. lagotricha is overharvested in zones - . because the maximum cpue may underestimate carrying capacity, this criterion provides only minimum estimates of the spatial extent of overharvest. in the model analysis, we related the total harvest for the area to the maximum total harvest at a given dispersal and reproduction rate because the maximum total harvest occurs at different levels of hunting effort for different dispersal and reproduction rates. for all scenarios, the maximum harvest occurred at an intermediate effort, and we examined three hunting scenarios in relation to the peak harvest ( fig. ) : good management ( % of maximum harvest; fig. a -d); moderate overharvesting ( % of maximum harvest; fig. e -h); and severe overharvesting ( % of maximum harvest; fig. j -m). we selected a harvest level of less than the maximum harvest to represent good management because ( ) this way total hunting effort is reduced, which is desirable for hunters per se and ( ) the maximum harvest is rather unstable because a small increase in hunting effort would lead to a considerable reduction in harvest (fig. ) . the analysis showed that the harvest and cpue within each patch depended predictably on the animal dispersal and reproduction rates. when a species with a low dispersal rate was overharvested, harvest rate was highest at very low hunting effort, and there was a sharp decrease in cpue from the minimum hunting effort to slightly higher efforts ( fig. j-k, dotted lines) . this occurred because individuals were exterminated in the heavily hunted areas around the village, and most animals were therefore robinson and redford ( ) . species were divided into four groups, depending on the shape in the relation between variables. group species showed a negative relation for both harvest rate and cpue with respect to hunting effort. group species showed a negative relation only between cpue and hunting effort. group species showed ambiguous results. group species showed only a positive relation between harvest rate and hunting effort. killed far from the village (fig. l-m, dotted lines) . for a well-managed population, on the contrary, the harvest diagram is almost linearly increasing and cpue only slightly decreased ( fig. a-b, dotted lines) . on the other hand, when a species with a high dispersal rate was overharvested, the pattern of harvest and cpue in relation to the local hunting effort (fig. j-k, solid lines) was almost indistinguishable from that for a well-managed population ( fig. a-b, solid lines) . in these cases, there was always an almost linear relation between local hunting effort and local harvest rate, and therefore almost no relation between hunting effort and cpue. this occurred because animals redistributed themselves much faster than depletion occurred in the heavily hunted area. at intermediate dispersal rates (fig. , hatched lines) , the differences between a well-managed and an overexploited population were discernible, although less apparent than at low dispersal rates. the effect of varying the animal reproductive rate had consequences similar to those of varying the dispersal rate (fig. ) . a high reproductive rate had the same effect as a low dispersal rate on the relation between local hunting intensity and harvest, and a very low reproductive rate had roughly the same effect as a high dispersal rate. these results should be understood in light of the fact that we related total harvest to maximum harvest for a given dispersal and reproductive rate. the model analysis showed how dispersal reduced differences in population densities, moved the peak of local harvest rates toward higher hunting efforts, and therefore affected the correlation between effort and harvest rate from positive for animals with a high dispersal rate to negative for animals with a low dispersal rate. this caused cpue at high dispersal rates to become constant across different levels of hunting effort, similar to the pattern that for species with low dispersal rate indicates no overharvesting. also, it showed that low reproductive rates can have effects similar to those for high dispersal rates. to use the spatial pattern of harvest and cpue to assess game depletion, one must take into account the rates of both reproduction and dispersal of a species. most of our study species have home ranges small enough that movements within them would not contribute to dispersal of a magnitude corresponding to that of a species with a high dispersal rate in the computer simulation (table ). this suggests that the dispersal mainly consisted of young individuals that leave their maternal home range. consequently, high dispersal rates occur only for animals with high reproductive rates, and it is therefore unlikely that species would have both a low reproductive rate and a high dispersal rate. most of our study species have fairly low reproductive rates ( table ) , meaning that only a small proportion of the population would be dispersing at any given time. it is therefore unlikely that high hunting intensity in the center of the area would depress population densities across the entire area, as it would for a severely overharvested, highly mobile species in the computer simulation ( fig. j-m, solid lines) . this supports our initial conclusions, with a few exceptions. the most important exception is t. pecari, which is seen only occasionally in sarayacu nowadays. although the spatial pattern of harvest and cpue suggest that this species is not overharvested, its high dispersal rate may have obscured the effects of intensive hunting. also, t. terrestris has a home range large enough to span two or three hunting-intensity zones, and the use of spatial pattern of harvest rate and cpue as indicators probably underestimated the extent of overharvesting. finally, the classification of a. belzebuth into group , representing species showing no signs of overharvesting, is a puzzle, given that a similar species, l. lagotricha, is severely overharvested. we believe that a. belzebuth, being a highly social species, actually increased its dispersal rate when its population density got so low that dispersing individuals had a hard time finding groups to join. the observed increase in harvest rate with increase in hunting effort therefore was probably a result of a high dispersal rate. thus, contrary to the initial conclusion, this species actually may be critically overharvested. we have shown how the status of hunted animal species in amazonia can be assessed based on knowledge about animal dispersal rates and the spatial distribution of harvest rates and cpue. the effects of animal dispersal have previously been documented in predator-prey systems (e.g., holt ; oksanen ) but have received less attention in the hunting literature. the inclusion of spatial structure and dispersal therefore provides a complement to earlier methods of evaluating the sustainability of hunting. for instance, robinson and redford's ( ) method may be more powerful if contrasting heavily hunted and less hunted areas on a relatively small spatial scale, as in our study. our analysis showed that their method failed to identify any species in our study area as overharvested (table ), but at the finer spatial scale (the seven zones of hunting effort) it did identify overharvested zones for some species (fig. a, e, & x) . similarly, our method may also be combined successfully with that of bodmer (robinson & bodmer ) . by performing a line-transect inventory and cpue measurements in the same area, it would be possible to establish a rough conversion factor from cpue to population density. the cpue values could then be converted into population density estimates for comparison with estimated carrying capacities or for calculating production. furthermore, our method and bodmer's method complement each other because line-transect inventories are more feasible in areas with high animal densities than in heavily hunted areas with low densities . on the other hand, calculating cpue is most feasible where hunting effort is fairly high but becomes problematic in areas with low hunting effort because of a small sample size. one problem with our method is that our indicators likely underestimated the spatial extent of overharvesting. the first indicator, a decreasing harvest rate with an increasing hunting effort, may do so because animal dispersal moves the peak of harvest rates toward higher hunting efforts, changing the correlation between local hunting effort and harvest rate from negative to positive. the second indicator, a low cpue, may underestimate the spatial extent of overharvesting because animal dispersal smoothes out differences in animal density and because the area with maximum cpue may also have reduced populations. however, these problems would be reduced through improved knowledge of animal dispersal rates. appropriate field methods for observing dispersal are available (e.g., campbell & sussman ; fragoso ) , and such data should be collected in a way that allows for quantitative expressions on dispersal rates (turchin ) . a second problem is that the usefulness of cpue as a proxy for population density depends on the selection of a proper unit of effort (salthaug & godø ; marchal et al. ) . the cpue estimates in our study could be improved by refining the classification of hunting methods. it would, for instance, be desirable to collect information on the use of dogs because hunters used dogs in zones close to the village but less so in remote areas. this may be one reason the cpue estimates were high for l. lagotricha in zone and why the maximum cpue for t. terrestris and t. tajacu was not found in zone but in zones of slightly higher hunting effort. similarly, it would be desirable to collect information on such hunting methods, such as digging out animals from burrows, or on the variability in walking speed between the wide trails near the village and the almost invisible trails in remoter areas. finally, our method assumes a steady state and therefore has reduced validity when change is rapid. until the rate of change can be verified by repeated observation, our method must be complemented with an assessment of past changes in hunting effort. our assessment, based on ethnographic sources, interviews, censuses, and retrospective mapping (see sadomba ) , is that hunting effort in our study area is increasing but at a fairly moderate rate (sirén ) . the main practical use of our method may be for identifying suitable locations for no-take areas. such areas may be the most viable option for wildlife managers in tropical forests. parallel to this research, we facilitated a process in the community of discussing the problems and possible solutions of wildlife depletion. community members suggested that the establishment of no-take areas may be a strategy with a potential for success. the management of such areas can be based on traditional arrangements of hunting rights and existing social structures, whereas banning hunting of certain endangered species may be less socially feasible. in the design of no-take areas, we suggest that a first step would be the identification of a limited number of target species, to reduce the complications of multispecies management. we further argue that these species should show clear indications of being overharvested but remain important sources of game meat. moreover, no-take areas should probably be established where animal densities are reduced but still high enough to have the potential to recover within a reasonable time span. unless a fairly quick recovery can be observed, motivation on the part of hunters to maintain and comply with hunting restrictions is likely to deteriorate. to adopt these criteria for the present situation, we suggest that three potential target species within the following zones have the most certain potential for fairly rapid improvement: l. lagotricha in zones and , t. terrestris in zone , and t. tajacu in zones to . in the final decision about where to allocate no-take areas, it will also be necessary to account for the cost of enforcement and the short-term cost to hunters in the form of lost hunting opportunities. our method provides a fairly low-cost alternative for assessing the status of tropical forest game species at a high spatial resolution, and therefore to inform decisions that could improve the sustainability of hunting in tropical forests. the sustainability of subsistence hunting in the neotropics radio telemetría en la urina mazama gouazoubira en el campamento cerro cortado, izozog home range, population density, and food resources of agouti paca (rodentia: agoutidae) in costa rica: study using alternative methods use and 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to theoretical ecology we thank the hunters who provided the data, the field assistants, and the government council of the sarayacu community. the geographic information system processing was done at the anthropological center for training and research on global environmental change at indiana university, with keen assistance from s. hetrick and e. brondizio. we thank j. bengtsson, g. meffe, and three anonymous reviewers for providing comments on the manuscript. the swedish international development authority (sida) financed the study. key: cord- - vyazby authors: sun, guanghao; nakayama, yosuke; dagdanpurev, sumiyakhand; abe, shigeto; nishimura, hidekazu; kirimoto, tetsuo; matsui, takemi title: remote sensing of multiple vital signs using a cmos camera-equipped infrared thermography system and its clinical application in rapidly screening patients with suspected infectious diseases date: - - journal: int j infect dis doi: . /j.ijid. . . sha: doc_id: cord_uid: vyazby background: infrared thermography (irt) is used to screen febrile passengers at international airports, but it suffers from low sensitivity. this study explored the application of a combined visible and thermal image processing approach that uses a cmos camera equipped with irt to remotely sense multiple vital signs and screen patients with suspected infectious diseases. methods: an irt system that produced visible and thermal images was used for image acquisition. the subjects’ respiration rates were measured by monitoring temperature changes around the nasal areas on thermal images; facial skin temperatures were measured simultaneously. facial blood circulation causes tiny color changes in visible facial images that enable the determination of the heart rate. a logistic regression discriminant function predicted the likelihood of infection within s, based on the measured vital signs. sixteen patients with an influenza-like illness and control subjects participated in a clinical test at a clinic in fukushima, japan. results: the vital-sign-based irt screening system had a sensitivity of . % and a negative predictive value of . %; these values are higher than those of conventional fever-based screening approaches. conclusions: multiple vital-sign-based screening efficiently detected patients with suspected infectious diseases. it offers a promising alternative to conventional fever-based screening. since the outbreak of severe acute respiratory syndrome (sars) in , infrared thermography (irt) systems have been used as border-control devices at most major international airports to screen passengers for fever. irt remains the gold standard for border control, because it can rapidly mass-screen infected individuals without contact. [ ] [ ] [ ] [ ] however, irt measurements are influenced by several factors, including the environmental temperature and humidity, alcohol consumption, and the consumption of antipyretic medications. body temperature, in particular, can be modified rapidly by the consumption of antipyretic drugs, which directly affects the sensitivity of irt. hence, fever-based screening using irt suffers from low sensitivity. this paper describes a combined visible and thermal image processing approach that uses a complementary metal oxide semiconductor (cmos) camera-equipped irt system that may address this issue. these systems have already been installed at most major international airports, and they can remotely sense several vital signs, including body temperature and heart and respiration rates, thereby facilitating the rapid and accurate screening of people who are suspected of carrying infectious diseases. the concept underlying vital-sign-based screening is based on the association between infections and inflammation. inflammation causes elevations in body temperature and in heart and respiration rates; therefore, integrating vital sign monitoring increases screening accuracy. this concept was used in previous studies by the present author group to develop a novel infection screening radar system to mass-screen individuals. this system utilizes a multisensor fusion technique to remotely measure heart and respiration rates using a microwave radar, and the facial skin temperature is measured using irt. the results from case-control studies that investigated seasonal influenza screening showed a detection accuracy that ranged from . % to . % using the heart and respiration rates and the facial skin temperature, which is higher than the detection accuracies of the conventional feverbased screening methods. [ ] [ ] [ ] [ ] however, the radar system used to screen for infections incorporates expensive embedded multisensor modules, namely a microwave radar, a reflective photoplethysmography sensor, and irt, and it requires large-scale systems. consequently, the system is not used widely. hence, to promote the widespread use of vitalsign-based screening, focus has been placed on systems with minimum hardware requirements to achieve a system that is more suitable for real-world settings. the most reliable solution is to enhance the functionality of the conventional irt systems that are already installed at international airports. by incorporating the latest advances in image processing techniques, these irt systems can acquire thermal and visible images together by integrating visible and thermal cameras. in this study, high image and temperature resolution irt that combines visible and thermal images was used to acquire multiple vital sign measurements from facial images using remote sensing. the benefit of this approach is that it only requires a cmos camera that is equipped with irt rather than a large-scale system. technical details of the system and the evaluation of its laboratorybased performance have been described in a previous publication. respiration rates are measured by monitoring the temperature changes around the nasal area that are associated with inspiration and expiration; the facial skin temperature can be determined easily from the thermal images simultaneously. the circulation of blood in the face causes tiny color changes that provide a visible facial image that can be used to determine the heart rate. a multiple logistic regression function is incorporated into the system to predict the possibility of infection; hence, irt can automatically detect infected individuals based on their vital signs, which are measured in real time. this system was tested on patients with an influenza-like illness in a clinical setting to evaluate the performance of this vital-sign-based screening approach using irt alone. visible and thermal image processing method to remotely sense multiple vital signs this method has been described in detail from an imageprocessing perspective in a previous publication. a cmos camera-equipped irt system (tvs- ; nec/avio infrared technologies co. ltd, tokyo, japan) was used; this is the same system that is used in the quarantine station at narita international airport in japan. the irt system integrates a cmos camera with thermography to capture visible and thermal images, respectively ( figure ). the visible and thermal images were recorded at a speed of frames per second and at a resolution of  pixels. the circulation of blood in the face causes tiny color changes on facial images that are undetectable with the human eye. the cmos camera uses this information to determine the heart rate. to measure the respiration rate from the thermal images, the temperature changes that occur around the nasal area during the inspiration of cold air from the environment and the expiration of warm air from the lungs was monitored, and the respiratory waveform was extracted from the differences in each of the thermal images. this enabled the respiration rate to be determined from the breath-to-breath intervals. the facial skin temperature was measured simultaneously using the thermal images. the image acquisition and processing programs were written in labview software (national instruments, texas, usa). subjects were seated in front of the irt system at a distance of approximately . m. the irt system displays the 'infection' or 'healthy' result within s using the logistic regression discriminant function, which bases the output on the heart rate, respiration rate, and facial skin temperature. this was a cross-sectional investigation that was undertaken at the takasaka clinic in fukushima in japan. the study involved outpatients ( male and five female) who visited the takasaka clinic with an influenza-like illness that included fever, headache, and sore throat, between january , , and february , . the ambient temperature (around . c) was also monitored to ensure reproducible environmental conditions. the average axillary temperature of the patient group was . c (range < . -< . c), and their average age was years. the healthy control subjects ( male and female) were students and admissions staff from tokyo metropolitan university, japan, none of whom had a fever, headache, or sore throat. the average axillary temperature of the control group was . c (range < . -< . c), and their average age was years. in this study, abnormal vital signs were defined according to the diagnostic criteria for systemic inflammatory response syndrome (sirs), i.e., ( ) body temperature > c or < c, ( ) heart rate > bpm, and ( ) respiration rate > breaths/min. this study was approved by the faculty of system design committee on human research at tokyo metropolitan university. logistic regression discriminant analysis to predict the possibility of infection based on the vital signs measured to distinguish between patients with infectious influenza and healthy control subjects, logistic regression discriminant analysis was used to establish a classification model based on the three derived vital signs. multivariable logistic regression analysis is a well-established statistical method that is used to analyze dichotomous outcomes in clinical practice; it is flexible and robust, and enables meaningful data interpretations. moreover, logistic regression analysis is much easier to implement in a real-time classification system, and saves computation time, compared with other classification methods such as neural network computation. the logistic regression discriminant function was defined as: where p i is the probability of the outcome of infection, b is a constant, b , b , and b are the regression coefficients corresponding to the respiration rate, heart rate, and facial skin temperature, respectively, and x , x , and x are the three vital sign variables of the respiration rate, heart rate, and facial skin temperature, respectively. the results from the logistic regression classification model were used to calculate the sensitivity, specificity, negative predictive value (npv), and positive predictive value (ppv) using a  contingency table. to avoid overfitting, a leave-one-out cross-validation was performed. the mean and standard deviation (sd) values of the three vital signs were calculated. the differences between the influenza patients and the healthy control subjects with respect to the three vital signs were evaluated using the mann-whitney u-test. a p-value of < . was considered to indicate statistical significance. the classification model was established using the data that described the three vital signs from the influenza virus-infected patients and the healthy control subjects using multivariable logistic regression. the statistically significant model is shown below: where x is the respiration rate, x is the heart rate, and x is the facial skin temperature. the derived logistic function, z(x ,x ,x ), was statistically significant (p < . ). the z(x ,x ,x ) value could be used to differentiate patients with influenza (z ! ) from healthy subjects (z < ). figure illustrates the discrimination results that were obtained by plotting the z(x ,x ,x ) values against the axillary temperatures of the two groups. of the patients with influenza, (red dots) are enclosed within the red ellipse and they had positive z-values, and two patients had negative z-values ( figure ). the healthy control subjects (blue dots) enclosed within the blue ellipse had negative z-values and none of the healthy subjects had a positive z-value ( figure ) . therefore, the sensitivity, specificity, npv, and ppv were . %, %, . %, and %, respectively. the fever-based screening, for which the cut-off value for the axillary temperature was set at . c, did not detect five influenza patients (false-negative). the sensitivity of the fever-based screening was . %. table presents a more detailed comparison of the patients with influenza and the healthy control subjects. the influenza patients who had higher z(x ,x ,x ) values had more severe symptoms, namely higher body temperatures and more elevated heart and respiration rates. the classification model determined that some patients had influenza, even if they did not have a fever. the z(x ,x ,x ) values could be used to evaluate the severity of infections, and they could, therefore, support the clinical risk stratification of patients. the two influenza patients who were misclassified had negative z-values because their vital signs were normal. the mean (sd) facial skin temperature of the influenza patients ( . ( . ) c) was . c higher than that of the healthy control subjects ( . ( . ) c). the mean (sd) heart rate of the influenza patients ( . ( . ) bpm) was . bpm faster than that of the healthy control subjects ( . ( . ) bpm). the respiration rate did not differ significantly between the influenza patients ( . ( ) breaths/min) and the healthy control subjects ( . ( ) breaths/ min) (figure ). an integrated visible and thermal image processing approach is proposed for the remote monitoring of multiple vital signs using irt, thereby enabling the rapid screening of infection in places of mass gathering. the results of this study demonstrate that the effectiveness of irt for the screening of infection can be greatly enhanced by measuring body temperature, as well as heart and respiration rates, using irt without any additional sensors. the high level of accuracy of the automated irt system has a number of clinical implications that could enable the system to be used to provide primary screening of people who may be carrying infections within emergency outpatient units or quarantine stations. moreover, this system saves time, because considerable amounts of time are required to investigate false-positive subjects when systems have low sensitivity levels and npvs. this technology also opens up new opportunities for controlling the spread of infections. for example, the present study was conducted at the takasaka clinic in fukushima prefecture, which is one of the three prefectures that were most affected by the earthquake and tsunami in japan. the risk of contracting infectious diseases, particularly influenza, increased after the earthquake and tsunami in fukushima, and healthcare table comparisons between the patients with influenza and the healthy control subjects. zðx ; x ; x Þ value (z ! ) x respiration rate (bpm) x heart rate (bpm) figure . mean (standard deviation) values were calculated for the three vital signs. the differences between the influenza patients and the healthy control subjects with respect to heart rate, respiration rate, and facial skin temperature were assessed. ns, not significant. professionals and medical facilities were severely affected by the disaster. , in such settings, an automated irt system could distinguish between individuals who are and are not carrying infections, thereby alleviating the workload of healthcare professionals. therefore, the proposed integrated visible and thermal image processing approach may be a promising pre-examination technique in disaster settings. limitations of the present study mostly pertain to data samples ( patients and healthy control subjects), which can be considered sufficient for evaluation by the cmos camera-equipped irt system for vital-sign measurement. however, the data samples are small for training in a logistic regression classification model. to refine the performance of the logistic regression classification model implemented in the irt system, field testing with larger and completely random subject populations will be conducted in realworld settings. moreover, to guarantee the accuracy of heart and respiration rate measurement by the irt system, the authors are now working on the development of an automatic real-time human face tracking algorithm using visible and thermal images. detecting and tracking human faces can significantly reduce motion artifacts, thereby extracting stable heartbeat and respiration signals. the face tracking algorithm can also be expanded to multi-person tracking, i.e., more than two human faces can be monitored simultaneously to avoid a 'human traffic jam' in places of mass gathering such as airports. in summary, the feasibility of using irt to remotely sense multiple vital signs and to rapidly and accurately screen patients who are suspected of carrying infectious diseases has been demonstrated, and it appears that this is a very promising approach that will provide an alternative to conventional feverbased screening. the authors state that they have no conflicts of interest to declare. airport arrivals screening during pandemic (h n ) influenza in new south wales, australia mass screening of suspected febrile patients with remote-sensing infrared thermography: alarm temperature and optimal distance analysis of ir thermal imager for mass blind fever screening modern approach to infectious disease management using infrared thermal camera scanning for fever in healthcare settings fever screening during the influenza (h n - ) pandemic at narita international airport a novel screening method for influenza patients using a newly developed non-contact screening system an infectious disease/fever screening radar system which stratifies higher-risk patients within ten seconds using a neural network and the fuzzy grouping method multiple vital-sign based infection screening outperforms thermography independent of the classification algorithm a novel infection screening method using a neural network and k-means clustering algorithm which can be applied for screening of unknown or unexpected infectious diseases non-contact measurement of respiratory and heart rates using a cmos camera-equipped infrared camera for prompt infection screening at airport quarantine stations advancements in noncontact, multiparameter physiological measurements using a webcam dimension reduction-based penalized logistic regression for cancer classification using microarray data clinical tests: sensitivity and specificity characteristics of infectious diseases in hospitalized patients during the early phase after the great east japan earthquake: pneumonia as a significant reason for hospital care infectious diseases following natural disasters: prevention and control measures monitoring of influenza viruses in the aftermath of the great east japan earthquake this work was supported by a grant-in-aid for young scientists (grant number k ) that was funded by the japanese ministry of education, culture, sports, science and technology. key: cord- -usr b dk authors: abdulah, deldar morad; hassan, a. b. title: relation of dietary factors with infection and mortality rates of covid- across the world date: - - journal: j nutr health aging doi: . /s - - - sha: doc_id: cord_uid: usr b dk objective: poor dietary habits are considered to be the second-leading risk factors for mortality and disability-adjusted life-years (dalys) in the world. dietary patterns are different based on cultural, environmental, technological, and economic factors. nutritional deficiencies of energy, protein, and specific micronutrients have been shown to contribute to depressed immune function and increased susceptibility to infections. we aimed to explore the relation of dietary factors with global infection and mortality rates of covid- in this study. design: in the current ecological study, the countries that had national dietary data from the global dietary databases of the united nations and coronavirus disease statistics from the world health organization (who) were included. the countries that had coronavirus disease statistics from the who were consecutively checked for the recent data of the dietary factors. setting: world. participants: countries across the world. measurements: infection and mortality rates of covid- ; dietary factors. results: the median crude infection and mortality rates by covid- were . (iqr: . ) and . (iqr: . ), respectively. the two highest percentage of the crude infection rate were between and ( . %) and – ( . %) per one million persons. the regression analysis showed that the crude infection rate has been increased by raising consuming fruits (beta: . ; p= . ) and calcium (beta: . ; p= . ) and was decreased with rising consuming beans and legumes (beta: − . ; p= . ). the analysis showed that the crude mortality rate was increased by raising consuming sugar-sweetened beverages (beta: . ; p< . ). whereas, the crude mortality rate by covid- has been decreased by increasing fruits consuming (beta: − . ; p= . ) and beans and legumes (beta: − . ; p= . ). conclusion: the present study showed the higher intake of fruits and sugar-sweetened beverages had a positive effect on infection and mortally rates by covid- , respectively. in contrast, the higher intake of beans and legumes had a negative effect on both increasing infection and mortality rates. poor dietary habits are considered to be the second-leading risk factors for mortality and disability-adjusted life-years (dalys) in the world. the poor dietary habits are responsible for . million deaths and . million dalys in ( ) . for example, the following dietary habits are among the leading risk factors for early death and disability in european countries. the habits are low intakes of whole grains, fruit and vegetables, and nuts and seeds, and high intakes of alcohol and sodium. the western dietary habits are consuming diet processed, high in red and processed meat, diets with high in sugar-sweetened beverages, and low in milk. these kinds of dietary habits are regarded to be a rising health concern. dietary patterns are different based on cultural, environmental, technological, and economic factors. however, the dietary patterns are becoming similar due to increasing living standards and growing globalization of the food sector ( , ) . mertens et al. ( ) explored the dietary intakes in four different european counters using individual-level dietary intake in adults in nationally-representative surveys of denmark, france, czech republic, and italy. they reported a higher intake of fruits and vegetables and lower intakes of sweetened beverages and alcohol in italy. while individuals in denmark and the czech republic had a higher intake of vegetables. a comparison of population subgroups within countries shows that there is a difference in the dietary preferences, beliefs, and practices for particular consumer groups. for example, highly-educated persons and women have a higher intake of fish, nuts, and seeds along with lower intake of red and processed meats ( ) . the individual-level reported dietary data of the countries could be used as a useful tool to make a connection between health and environment with foods as their common denominator ( ) . a recent review study reported that the detailed assessment of patients for the dietary and nutritional risks along with medical, lifestyle, and environmental factors with suitable risk management strategies make the sensible way to deal with the covid- ( ) . the diet and nutrition have a variance impact on the immune system competence. in addition, they determine the risk and severity of the infections. the relation between diet, nutrition, infection, and immunity is bidirectional ( ) . the macro-, micronutrients, and phytonutrients in diet, such as fruits and colorful vegetables improve healthy immune responses. the microand phytonutrients provide the antioxidants and the antiinflammatory nutrients, like beta-carotene, vitamin c, vitamin e, and polyphenolic compounds resulting in modulating the immune functions ( , ) . nutritional deficiencies of energy, protein, and specific micronutrients have been shown to contribute to depressed immune function and increased susceptibility to infections. the sufficient intake of iron, zinc, and vitamins a, e, b , and b is vital for the overall maintenance of immune function ( ) . the new epidemics of coronavirus disease (covid- ) has become a pandemic to the world currently. we make a hypothesis that geographical variation in dietary factors could have a role in infection and mortality rates of covid- in the world. therefore, we aimed to explore the relation of dietary factors with global infection and mortality rates of covis- in this study. in the current ecological study, the countries that had national dietary data from the global dietary databases of the united nations ( ) and coronavirus disease statistics from the world health organization (who) were included ( ) . the countries that had coronavirus disease statistics from the who were consecutively checked for the recent data of the dietary factors. the countries/states met eligibility criteria for this investigation if they had the statistics from the who coronavirus disease (covid- ) situation dashboard from the website of the world health organization by april ( ) . the following countries were excluded from the analysis due to not having the statistics of the covid- ; comoros, north korea, kiribati, lesotho, malawi, marshall islands, micronesia, nauru, palau, samoa, sao tome, and principe, solomon islands, south sudan, tajikistan, tonga, turkmenistan, tuvalu, vanuatu, and yemen. the following countries were excluded from the study due to not having data on the national dietary factors on the website of the global dietary database ( ) the populations of the countries were extracted from the united nations statistics division ( ) . the estimated populations of the year were considered for the countries. some of the countries had not the population for the year . therefore, the authors checked for the years , , and . accordingly, the population of was used for the following country; algeria. the population of was considered for the following countries: lybia; sierra leone. the population of was extracted for the following countries: mali; mauritania; papua new guinea; sudan and for the following countries; bhutan; bosni; burkina faso; fiji; guyana; niger; nigeria; pakistan; uae. the populations of the following countries were not available for the - period. therefore, the population of the following countries was not included in this study based on the eligibility criteria. these countries were the central african republic; djibouti; djibouti; dominica; gabon; kosovo; lebanon; liberia; moldova; russia; saint kitts and nevis; syria; somalia, the democratic republic of the cong. finally, countries/states were included in this study. the general characteristics of the countries were presented in median (interquartile range [iqr], mean (std. deviation), and number (percentage). the confirmed and dead cases were presented in median and interquartile range due to the nonnormal distribution of the data. the normality of the outcomes was examined in drawing a histogram and box plot. the number of confirmed cases was divided by the total population of a country multiplied by , to obtain the infection rate of covid- per one million persons. the number of dead cases was divided by the total number of confirmed cases and divided by total population multiplied by , to obtain the mortality rate/ , persons.. the infection and mortality rates were determined in a median and interquartile range following dealing with the potential outliers. the upper limit values were considered for the extremely higher limit values in the infection and mortality rates. the crude infection rate was categorized into the following groups; - ; - ; - ; - ; - ; and > per one million person. the infection and mortality rates were transformed through the ln technique to obtain a normally distributed histogram. no ethical aspect was applicable to this study. the median crude infection rate by covid- was . (iqr: . ) ranged between . and . per , persons. the median mortality rate by covid- was . (iqr: . ) ranged between . and . per , persons. the two highest percentage of the crude infection rate were between and ( . %) and - ( . %) per one million persons ( table ) . the study showed the crude infection rate was raised with increasing consuming fruits (r= . ; p< . ), unprocessed red meats (r= . ; p< . ), fruit juices (r= . ; p< . ), total protein (r= . ; p< . ), calcium (r= . ; p< . ), potassium (r= . , p< . ), and total milk (r= . ; p< . ). regarding crude mortality rate per , persons; the study showed that crude mortality rate was raised with increasing consuming unprocessed red meats (r= . ; p= . ), sugar sweetened beverages (r= . ; p= . ), fruit juices (r= . ; p= . ), calcium (r= . ; p= . ), and total milk (r= . ; p= . ). however, the mortality rate was decreased following increasing consuming non-starchy vegetables (r=- . ; p= . ), see table . the regression analysis showed that the crude infection rate has been increased by raising consuming fruits (beta: . ; p= . ) and calcium (beta: . ; p= . ). however, the infection rate was decreased with rising consuming beans and legumes (beta: - . ; p= . ), table . the effect of dietary factors on the crude mortality rate by covid- was examined in the regression analysis. the analysis showed that the crude mortality rate was increased by raising consuming sugar-sweetened beverages (beta: . ; p< . ). whereas, the crude mortality rate by covid- has been decreased by increasing fruits consuming (beta: - . ; p= . ) and beans and legumes (beta: - . ; p= . ), as presented in table . the comparison of dietary factors in countries with different infection rates was examined in table and fig . the study showed that the countries with higher infection rates between and above had a higher intake of fruits (p= . ), fruit juices (p< . ), calcium (p< . ), potassium (p< . ), and total milk (p< . ). however, these countries had a lower intake of unprocessed red meats (p< . ) and total protein (p= . ). the aim of the food-based dietary guidelines is to maintain the general health of the population and prevent non-communicable diseases ( ) . most of the food-based dietary guidelines recommend intake of whole grains, fruit and vegetables, low-fat dairy and fish, and low intake of red and processed meat, sugar-sweetened food products, alcohol, and salt ( ) . the present study showed that the crude infection rate by covid- has been increased by raising consuming fruits, calcium and decreased with increasing consuming beans and legumes. regarding the mortality rate, the analysis showed that the crude mortality rate was increased by raising consuming sugar-sweetened beverages and decreased by increasing fruits consuming and beans and legumes. the anti-inflammatory strategies inside foods, nutrients, or ( , ) since the coronavirus has serious inflammatory consequences for acute pneumonia in persons ( ) . the human coronavirus infections cause mild to severe diseases, systemic inflammation, high fever, cough, and acute respiratory tract infection and dysfunction in internal organs leading to death. this virus is classified as a ribonucleic acid (rna) virus. the virus has a genome that often escapes the innate immune system, particularly if it is malfunctioning ( ) . entering coronavirus into the organism activates innate immunity, which intervenes in the first instance to engulf the invader. the severity of the diseases locates within the ability of innate immune cells to stem viral infection ( ) . the virus has less ability to replicate itself and induce the pathological state in the case of the stronger innate immune system. when the immune system is suppressed by the virus, the body activates the adaptive immunity. the coronavirus enables to produce viral enzymes and proteases. these enzymes and proteases can damage the immunity and inhibit the signaling pathways of type i interferon (ifn) along with the nuclear factor-κb, facilitating innate immune evasion ( ) . apart from the age-related micronutrient inadequacy, the nutritional status of a person has a role in the developing risk of sars-cov-ii infection, the clinical course, and the disease outcomes. hence, the maintenance of host macro-and micronutrient status is considered to be a crucial preventive measure for covid- ( ) . the coronavirus infection is primarily attacked by immune cells, however, the virus has developed viral proteins overtime that counteracts with the innate immune system ( ) . some of the viral proteins antagonize interferon (inf) and stimulate inflammatory proteins, such as il- family member cytokines ( ) . the inflammatory state and pathogenesis of the disease are escalated after abnormal production of cytokines as shown in sars ( ) . our hypothesis is that the higher intake of fruits makes the persons at further risk of infection by the covid- . despite fruits and vegetables have anti-inflammatory and antioxidant factors and have an important role in enhancing the immune system responses ( ) . but higher intake of these micronutrients makes a barrier in improving the human immune system or response to the pathogens due to the role of the fruits with a high glycemic index. our study showed that beans and legumes have a positive role in reducing the infection rate by the covid- . the human body requires the substates in the plant proteins to improve or respond to the vial pathogens because of the human body unable to produce these substrates ( ) . therefore, the body needs these substates to protect the organs against the coronavirus. we assume that the immune body system unable to recognize the virus at the early times. comparison of dietary factors in countries with different infection rates therefore, the available proteins are essential for the body to make a response to the pathogen. the beans and legumes have been effective to reduce the rate of mortality by the covid- as well. the role of age in the suppression of the immune system must not be overlooked. the population of the countries with a higher infection rate is older compared to the counters with a low infection rate ( ) . for example, france and italy compared to iraq and saudi arabia. the available evidence indicates that adults aged years and older and patients with preexisting medical conditions are more likely to have sever-even deadly-coronavirus infection that other population groups ( ) . therefore, we can make the further hypothesis that the aged population of the countries with high infection rates has been the main factor in the low immune system. the impacts of aging on the immune system can reflect at multiple levels. the levels are decreased production of b and t cells in bone marrow and thymus and diminished functions of mature lymphocytes in secondary lymphoid tissues. so, the elderly persons do not respond to immune challenges as robustly as the young individual ( ) . the higher intake of fruits and vegetables may not be beneficial to enhance the immune system in aged populations. diet alone may be insufficient and tailored micronutrient supplementation based on specific age-related needs necessary ( ) . many micronutrients are required for immune-competence, especially vitamin a, c, d, e, bs, iron, selenium, and zinc. moreover, the dietary pattern is essential to maintain the nutritional status of an individual. however, the diet alone could not be adequate in certain metabolic and lifestyle conditions, such as elderlies, co-existing medical conditions, cigarette smoking, or occupational exposure to environmental toxins ( ) . the fruits have several vitamins and minerals. the fruits at a ground level may not be quite suitable to make the final judgment. the older persons over the age of - experience some immune dysregulation with less ability to respond to immune challenges and response to pathogens, antigens, and mitogens decreases ( ) . the decrease in the number of circulating lymphocytes and loss of immune cells are characteristics of the immune system in older people ( ) . moreover, the older peoples have reduced the production of t cells in the involved thymus and consequently diminished function of mature lymphocytes in secondary lymphoid tissues ( ) . the lifetime of exposure to antigens and to several sources of oxidative stress cause dysregulation in the immune system that makes them at further risk of infections than other age groups ( ) . the role of fruits in enhancing immunity, such as micronutrients is in exhibiting pleiotropic roles in supporting immune function. the vitamins and minerals support to develop and maintain the physical barriers, produce and activate antimicrobial proteins ( ) . some other mechanisms of micronutrients are supporting the growth, differentiation, and motility/chemotaxis of innate cells; phagocytic and killing activities of neutrophils and macrophages, and promotion of and recovery from inflammation (e.g. cytokine production and antioxidant activity ( ) . the potential mechanisms of the fruits may back to the antiviral immune induction, the modulation of immunoregulatory defense, induction of autophagy and apoptosis, genetic or epigenetic regulation ( ) . stimulation of defensins and cathelicidins may reduce the replication of the virus and raise the levels of anti-inflammatory cytokines, and reducing levels of pro-inflammatory cytokines ( ) . here our hypothesis is that a higher intake of fruits suppresses the role of stimulation of defensins and cathelicidins. the common denominator that reflects the role of nutrition and dietary recommendations against viral infections; including covid- is the relation between diet and immunity ( ) . this is why we made our hypothesis based on the immunological effects of a higher intake of fruits in patients with covid- by taking into account the patients' ages. the evidence highlights that diet has an important effect on the immune system and disease vulnerability of peoples. the role of nutrients or nutrient combinations back to their effects on the immune system through the cell activation, modification in the production of signaling molecules, and gene expression ( ) . the relation of fruits and beans and legumes on crude mortality rate is weak (p= . and p= . , respectively) in contrast with the strong relation of sugar-sweetened beverages (ssbs) (p< . ). the possible role of sugar-sweetened beverages on infection rate may back to its role in weight gain and the risk of obesity. a review study of observational and clinical trials showed that a higher intake of ssbs raised the risk of weight gain and obesity ( ) . the evidence has been confirmed elsewhere ( , ) . accordingly, maccioni et al. ( ) recruited individuals aged - in a cross-sectional study on airway infection in germany. the study reported that obese persons have a consistently higher frequency of upper and lower respiratory tract infections (rtis). the evidence has been reported elsewhere ( , ) . obesity is responsible for the dysregulation of the immune system through mediation in different immune, metabolic, and thrombogenic responses ( ) . the higher intake of ssbs has been reported in high-income countries ( ) . the effect of higher calcium intake on raising infection rates could be due to the effect of calcium on the risk of some other chronic diseases rather than its direct effect. a meta-analysis showed the increased incidence of myocardial infarction in persons who consume higher levels of calcium with a pooled relative risk of . , % confidence interval . to . , p= . ( ) . in addition, calcium has been reported as a trigger for ischemic cell death ( ) . the daily recommended allowance/intake of the dietary factors are different across the countries. it is required to mention that food intake varies markedly based on the sociodemographic factors; like age gender, and educational level. we did not make stratification the results of the study based on the socio-demographic aspects since the who has not published the covid- confirmed cases according to age, gender, and educational level. besides, the cross-country caparison of individual-level dietary data is challenged by the dietary surveys performed with various survey characteristics and data collection methods with a possible influence in the comparison of the results. however, we used the fao dietary data that represent the nationally representative sample of all age-sex, and educational level categories. the present study showed the higher intake of fruits and sugar-sweetened beverages had a positive effect on infection and mortally rates by covid- , respectively. in contrast, the higher intake of beans and legumes had a negative effect on both increasing infection and mortality rates. the possible reason for the role of fruits and sugar-sweetened beverages on infection and mortally rates back to the indirect effect of weight gain and obesity and the role of age. the authors do not declare any conflicts of ineptest. global, regional, and national comparative risk assessment of behavioural, environmental and occupational, and metabolic risks or clusters of risks, - : a systematic analysis for the global burden of disease study importance of government policies and other influences in transforming global diets global panel on agriculture and food systems for nutrition: food systems and diets: facing the challenges of the st century geographic and socioeconomic diversity of food and nutrient intakes: a comparison of four european countries meatless days" or "less but better"? 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on risk of myocardial infarction and cardiovascular events: meta-analysis calcium in ischemic cell death key: cord- - c qsek authors: paul, s. k.; jana, s.; bhaumik, p. title: on nonlinear incidence rate of covid- date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: c qsek classical susceptible-infected-removed model with constant transmission rate and removal rate may not capture real world dynamics of epidemic due to complex influence of multiple external factors on the spread. on top of that transmission rate may vary widely in a large region due to non-stationarity of spatial features which poses difficulty in creating a global model. we modified discrete global susceptible-infected-removed model by using time varying transmission rate, recovery rate and multiple spatially local models. no specific functional form of transmission rate has been assumed. we have derived the criteria for disease-free equilibrium within a specific time period. a single convolutional lstm model is created and trained to map multiple spatiotemporal features to transmission rate. the model achieved . % mean absolute percent error in terms of cumulative infection cases in each locality in a -day prediction period. local interpretations of the model using perturbation method reveals local influence of different features on transmission rate which in turn is used to generate a set of generalized global interpretations. a what-if scenario with modified recovery rate illustrates rapid dampening of the spread when forecasted with the trained model. a comparative study with current normal scenario reveals key necessary steps to reach baseline. ynamical systems equations based on compartmental modelling of epidemiology have been widely used to predict the spread of an epidemic. susceptible-infected-removed or sir model is one such simplified set of differential equations to model the spread. however, accurately determining parameter values like the transmission rate for a specific disease is a challenge. the dynamics of a disease may vary across space and time. many external factors may influence the transmission rate. considering the transmission rate constant for a disease, grossly oversimplifies the model, thus compromising accuracy. secondly, knowing the factors influencing the transmission rate and the dynamics of the influence can provide a vivid understanding of the disease progression. there are several different types of nonlinear incidence rate suggested in the literature [ , , , , , , ] . however, most of them adopt some type of simple predefined function with few parameters to model the incidence rate. simple functions have low representational capability. thus, they may not capture the detail dynamical variations of the incidence rate caused by multiple factors. we propose a convolutional lstm based spatiotemporal model to map the transmission rate of covid- with respect to multiple input features and thereby map the derived incidence rate from transmission rate. the model can forecast incidence rate with high spatiotemporal resolution provided availability of clean historical data in that resolution. exploratory analysis reveals probable influence of external features on transmission rate and eventually helped in feature selection. a spatiotemporal local interpretation method of a black box model is proposed which in turn is used to explain the trained model. the explanations reveal local influence of different external features on the transmission rate. a generalized global explanation is also generated to find common influence of factors across multiple locations and over a period. we experimented with available data of covid- across multiple regions of usa and the model achieved . % and . % mean absolute percent error in terms of new infection cases in each locality and cumulative total infection cases across the country in a -day prediction period respectively. the generated explanations revealed high influence of population density, somewhat medium influence of gender ratio and median population age on the transmission rate, globally. there are minor influences of temperature and temperature deviation but barely any observable influence of humidity. however, local influences of features vary widely across multiple small regions. a criterion for disease-free equilibrium within a specific time period has been derived for discrete sir model with variable transmission and recovery rate. a long-term forecast using the trained model and modified recovery rate to satisfy disease-free equilibrium criteria reveals rapid damping of active infection cases to reach the baseline. however frequent spikes due to resurgence are seen in this scenario. a comparative study is made with forecasted dynamics using current normal recovery rate to reveal necessary actions for rapid containment of the disease. the paper is organized as following. we conducted a brief literature survey in section . section briefly explains the discrete sir model with variable transmission rate. section discusses about spatiotemporal modelling of transmission rate. section discusses on spatiotemporal influence ----------------of external features on transmission rate. we conduct long term forecasting of disease progression with a current normal scenario and a "what-if" scenario in section . section concludes the paper. kermack and mckendrick [ ] modelled communicable diseases using differential equations. hethcote introduced the sir model [ ] where population is compartmentalized into susceptible, infected and removed groups. a set of differential equations modeled the dynamics of population in different compartments. in traditional sir model incidence rate or the number of new infections per unit time varies bilinearly with the number of infections and number of susceptible in a population considering the transmission rate as constant. however, assumptions like homogenous mixing, non-dependence on external factors, no psychological effects on population etc. may not be realistic in many cases. thus, several authors [ , , , , , , ] introduced different types of non-linear incidence rates mostly addressing the saturation and psychological effect. saturation effect states that the incidence rate might slow down and saturate as number of infected individuals increases due to low availability of susceptible individuals. psychological effect on the population results in increased cautiousness among susceptible individuals as the epidemic spreads thus, slowing down the transmission rate. most of the incidence rates stated above satisfy weakly non-linear property and are too simple to capture any arbitrary effects of the environment. sir model with time varying transmission recovery rate have been studied in [ ] and thresholds theorems are derived. liu et. al. [ ] introduced a time varying switched transmission rate to model nonlinear incidence. hu et. al. developed a modified stacked autoencoder model of the epidemic spread in china and they claimed to achieve high level of forecasting accuracy [ ] . on observing a universality in the epidemic spread in each country, fanelli and piazza [ ] applied mean-field kinetics of susceptible-infected-recovered/dead epidemic model to forecast the spread and provided an estimation of peak infections in italy. zhan et. al. [ ] integrated the intercity migration data in china with susceptible-exposed-infected-removed model to forecast an estimation of epidemic spread in china. hong et. al. [ ] considered variable transmission rate of covid and came up with variable rnaught factor of covid- . xi et. al. [ ] used deep residual networks to model spatiotemporal characteristics of the spread of influenza and experimented with real dataset of shenzhen city in china. paul et. al. [ ] used ensemble of convlstm networks to forecast covid- total infection cases. in sir model the total population in a region is compartmentalized into classes, namely susceptible (s), infected (i) and removed (r). initially the whole population is in susceptible class. an individual can move from susceptible to infected class on contracting the disease. an infected individual can move to removed class by either getting recovered and immune to the disease or deceased. the dynamics of the disease spread can be modelled by the following set of differential equations. where ( ) is disease transmission rate or contact rate and ( ) is removal rate which is sum of recovery rate and mortality rate. it is assumed the population size ( ) remains constant during the course of epidemic. ( ), ( ) and ( ) are scaled as fraction of total population. thus, the following equation holds true. from [ ] we get the following ∀ > , where = ( ), ( ) ≥ ∀ > and ( ) ≥ we consider discrete time steps in our modelling and measurements are taken on daily basis. thus, replacing differential with difference equation. solving for ( ) expanding log as taylor series and taking only the first term, considering a constant average difference between transmission rate and removal rate = − within the period considering ( ) < as disease free equilibrium state, the upper bound of can be derived as following such that the epidemic reaches baseline in time t. maintaining > asymptotically converges the total infection count to at exponential rate thus makes the disease-free equilibrium stable. assuming a constant mortality rate, from ( ) it can be deduced that increasing the recovery rate will directly reduce the time span of the disease outbreak. however, there is a hard limit for the removal rate, ( ) ≤ . but ( ) can be greater than , specially during initial outbreak when total infection count is low. in such situation dampening the . cc-by . international license it is made available under a preprint in perpetuity. is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint spread of infection will not be possible only with treatment facilities. immediate restriction of mobility in area of outbreak and rapid isolation of infected individuals can reduce the transmission rate. once it comes down below , enhanced treatment facilities can increase the recovery rate, thus reducing the span of the disease outbreak. the transmission rate can vary spatially as well as temporally based on multiple variables. geographical location, weather conditions [ ] , human mobility [ ] , population statistics might be some of the impacting factors changing the dynamics of the spread. an exploratory analysis reveals probable dependency of multiple spatial and temporal features on the transmission rate. spatially co-located regions might have similar dynamics of the spread with high autocorrelation of transmission rate in a localized region. however distant regions may have dissimilar transmission dynamics with low correlation. thus, a large geographic area has been divided into small regions called as grids. each grid has been divided even further into smaller regions called pixels. a population within a pixel is assumed to be constant and transmission dynamics is modeled by separate sir models for each pixel. each grid consists of co-located regions which might be impacting each other's transmission rate. feature is constructed for each grid as multichannel temporal sequence of matrices which in turn used for training a convlstm [ ] network to model the transmission rate. data has been obtained for a region in united states from multiple sources [ , , , , , , ] . the time span of the data is from - - to - - . covid daily data at usa county level are filtered by a spatial region of usa as shown in fig. . the region is geospatially divided in m x n grids of equal sizes bounded by calculated latitudes and longitudes. fig. a illustrates a grid bounded by latitudes and longitudes. the dotted line box is called as frame. the overlapping areas in all directions in a frame allows flow of spatial influence from neighboring grids. a frame is in turn divided into l x l pixel. each pixel represents a bounded area in geospatial region. each pixel contains a value mapped to certain feature in the bounded geospatial region. frame matrices are constructed for each feature and concatenated through a third axis called channels. for example, transmission rate and population density are two features and they represent two separate l x l matrices in a frame concatenated across a third axis. some features like transmission rate, active infection fraction, weather etc. are distributed spatio temporally. whereas other features like population density, female fraction, median age are assumed time invariant and have no temporal component. thus, they are only distributed spatially and copied along temporal axis. population density has been log transformed to reduce skewness and normalized. other features are only normalized in - scale. daily transmission rate and removal rates at pixel level have been calculated as following, where ∈ { . . } denotes each pixel, ∆ + ( ) and ∆ ( ) are fraction of new cases in infected class and new individuals in removed class respectively at time in pixel . each training sample of a frame is represented by a tensor of dimension t x l x l x c, where t is the total time span and c is number of channels or features. as shown in fig the forecasting problem is framed as supervised learning problem. given a sequence of observed multichannel frames of spatial data as matrices , … the objective of the model is to predict the next single channel frame + . the training samples are divided into input sequences of length w and output frames. the model forecasts the transmission rate in each pixel in a frame for each timestep. thus, the output frame consists of only channel. the input training dataset (x train ) can be represented as a tensor of size s train x w x l x l x c and the output dataset (y train ) as is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . s train x w x l x l x . for training, the input sequences are selected from all frames having non-zero total infection count. fig. b illustrates the sequence of a frame. the frames t- to t- represents an input training sequence (x train ) of length w. the output frame (y train ) for this training sample is t- . other training samples are generated by sliding the window w+ backwards in time by . the most recent images t- and t- represents the test output images (y test ) and immediate sequence of images t- to t- is the test input sample (x test ). the test set x test is represented by a tensor of size (m * n) x w x l x l x c and y test by (m * n) x w′ x l x l x . the primary purpose of the exploratory analysis is to understand the distribution of transmission rate and identify probable influence of different features on the transmission rate. eight external features are analyzed against transmission rate to find probable influence. among eight features, four are spatial features having no temporal component, namely population density, housing density, female fraction, median age. fig. illustrates scatter charts between average transmission rate and four spatial features for multiple pixels. the color gradient represents log transformed cumulative number of infection cases in each pixel. only those pixels are filtered which experienced at least days of running infection cases and having at least cumulative infection cases at the beginning of the observation period. fig a and b displays scatter charts and regression lines of average transmission rate with respect to population density and housing density in each pixel respectively. the two external features are log transformed and scaled to get upper bounded by . log transformation reduces skewness and influence of outliers in data. as observed in the charts the transmission rate is positively correlated with both the features which is quite intuitive. places with high population density is expected to experience rapid spread of the disease. locations with high population density also experienced highest number of cumulative cases. fig. c and b displays scatter charts and regression lines of transmission rate with respect to female fraction and median age of the population respectively. in fig c, pixels have been filtered out having female fraction less than . to remove the skewness in the data. there is a slight positive correlation between female fraction and transmission rate. however, this might not invoke a suggestive idea about the dependency of this external feature on transmission rate as majority of the pixels resides in the range of . - . female fraction with barely any trend in that range. also, there is an indirect correlation as in general pixels with high female fraction has high population density. median age has negative correlation with transmission rate. there is an indirect correlation in this case also as in general pixels with high median age has low population density. another intuitive assumption can be, population with high median age are less mobile thus is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint restricting the spread of the disease. apart from four spatial features four other external spatiotemporal features are analyzed to observe any influence on transmission rate. fig. illustrates time lagged cross correlation between transmission rate and other spatio-temporal features at pixel level. the external features are time lagged from to time steps and cross correlated with transmission rate for each lag. in the plot, pixels are arranged in increasing order of total infection cases. fig. a and b shows the plot of cross correlation of transmission rate with respect to average daily temperature and -day running window temperature standard deviation respectively. average temperature is slightly positively correlated in time lag range of - . in the plot, offset denotes time lag and offset as time lag . the correlation with temperature variation varies widely across pixels. however, on average there is a minor positive correlation in time lag range of - . for both the features pixels having high total infections have negative correlation with transmission rate in the time lag range of - . fig. c and d shows the plot of cross correlation of transmission rate with respect to average daily relative humidity and daily removal rate respectively. there is an overall positive correlation with respect of relative humidity specially in pixels with highest infection cases. removal rate is mostly negatively correlated with transmission rate except in few pixels having highest infection cases. correlation might not represent causality. thus, we performed granger causality test [ ] of transmission rate with respect to different features. granger causality is a statistical hypothesis test for finding if one time series can help improving the forecasting accuracy of another time series. it might not measure true causality rather it measures predictive causality. chi square test is chosen as the hypothesis testing method and minimum pvalues for each pixel are calculated. augmented dickey-fuller test [ ] is performed to test stationarity of all the timeseries. table displays the result of granger causality and dickey-fuller tests. the column '% of pvalue < . ' represents percentage of pixels for which the granger causality test gave pvalue less than . for each feature. the column '% of adf< %' represents percentage of pixels for which the dickey-fuller test gave test statistic less than % critical value and having pvalue less than . for each feature. from the observed results it seems for majority of the pixels the weather features and removal rate have predictive causal relation with transmission rate. also, for majority of the pixels the feature timeseries are stationary or weakly stationary. recurrent neural networks (rnn) are a class of artificial neural networks with nodes having feedback connections thereby allowing it to learn patterns in variable length temporal sequences. however, it becomes difficult to learn long term dependencies for traditional rnn due to vanishing gradient problem [ ] . lstms [ ] solve the problem of learning long term dependencies by introducing a specialized memory cell as recurrent unit. the cells can selectively remember and forget long term information in its cell state through some control gates. in convolutional lstm [ ] a convolution operator is added in state to state transition and input to state transition. all inputs, outputs and hidden states are represented by d tensors having spatial dimensions and temporal dimension. this allows the model to capture spatial correlation along with the temporal one. in our model we configured multichannel input such that distinct features can be passed through different channels. multiple convolutional lstm layers are stacked sequentially to form a network with high nonlinear representation. the final layer is a d convolutional layer having one filter which constructs a single channel output image as the next frame prediction. we assume the transmission rate saturates as number of infection cases increases. thus, the modified transmission rate is calculated as ′ ( ) = ( ) * (τ + ( )) which serves as the response variable for the model and τ = / and is total population in pixel . the model is tested by feeding in input sequence of frames and next output frame is predicted which in turn is combined with other features along channel and appended with the input sequence. the new input sequence is fed to the model again to get the next predicted frame. this continues until forecasting completes for a desired time period. "mean absolute percent error" (mape) and kullback-liebler (kl) divergence [ ] are used to measure the accuracy of the model. the model predicts the transmission rate for a future time period for each pixel which in turn is used to calculate daily new infection cases ∆ + ( ) using equation . the removal rate is estimated as running average of previous -days and daily removed cases are calculated using equation . the active infection cases ( ( )) and susceptibles ( ( )) are calculated using equation and . cumulative infection cases (∑ ∆ + ( )) are calculated by summing up all new infection cases upto a certain day. mape of modified transmission rate is calculated at pixel level for the prediction period and averaged. the pixels with susceptible population count are filtered out while calculating mape and kl divergence. pixel mape is calculated as per equation , where g is set of all grids and g′ set of all pixels such that the frame for each corresponding grid have non zero cumulative infection count, ′ is prediction time period, ′′ = − ′ is total time period in training set, ̂′ ( ) and ′ ( ) are predicted and actual modified transmission rate for ℎ pixel at time respectively. kl divergence at pixel level is calculated for modified transmission rate in the prediction period to measure the dissimilarity of distribution of predicted transmission rate with respect to actual. is softmax function applied after . cc-by . international license it is made available under a preprint in perpetuity. is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . scaling a series in to scale and ( ) is probability distribution of . softmax is applied to convert total infection cases as probability distribution across pixels. since kl divergence measures the dissimilarity between two distribution thus a lower value of it indicates better performance of the model. mape is also calculated at grid and country level with respect to cumulative predicted infection cases across the region during the prediction period. the model is constructed by stacking convolutional lstm layer sequentially and terminating the network with a convolutional d layer. the final layer is followed by exponential linear unit as activation. the input and other hidden convolutional lstm layers are followed by sigmoid activation. each convolutional lstm layer has filters and kernel size x . the input layer is configured to take tensors of size x x . eight input features are constructed and fed into the model as separate channels. namely transmission rate, population density, female fraction, median age, active infection fraction, average temperature, temperature standard deviation and average relative humidity. the model is trained for epochs with batch size of and mean squared error as loss function. out of samples are used for training the model and are for validation. the model is trained and tested twice. once with all the eight features another with only five leaving out the weather features. the dataset has a time span of days out of which data from nd to st day is used for testing the model and rest for training and validation. table displays the training, validation and test results of the model. statistics suggests there is a slight improvement of overall accuracy when weather features are included while training the model. pixel mape and grid mape are below % in both the cases and country mape is below %. predicted total infection cases at the end of prediction period is little overestimated than actual ( ) when weather features are included in modelling and overestimated when weather features are not included. all future reference of trained model suggests the model has been trained with all eight features unless otherwise mentioned. fig. illustrates different plots of predicted vs actual infection cases in -day prediction period. fig. a and b shows the plot of predicted vs actual new infection cases and cumulative infection cases per day in -day period. fig. c and d shows the plot of predicted vs actual log transformed total new infection cases and cumulative infection cases per grid in -day prediction period. all the predicted curves closely approximate the actual values. one of our goal of this study is to understand how different external features are influencing the transmission rate. we expect to find simple interpretable predictive causal relations between transmission rate and different features. one of the ways to find such relations is building an accurate predictive model followed by explaining the predictions in terms of input features. as described in previous sections deep neural networks can model the dynamics of epidemic quite accurately due to its high nonlinear representation. however high accuracy is tradeoff against model interpretability. given the complexity of the convolutional lstm network used to model the transmission rate it is nearly impossible to find how each feature is influencing the transmission rate just by studying the weight matrices. using a high bias predictive model like linear regression or shallow decision tree not only is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint reduces the accuracy but also drops interpretability [ ] . simple models can serve as interpretable models but may fail to capture true relations among features globally. this problem can be solved by building simple local models and drawing local explanations of feature relations. however, there may not be enough data points available or data distribution may be highly skewed in a local region to confidently build a predictive model and draw interpretations on it. thus, we use the trained convolutional lstm model as the global model and draw spatio-temporal local interpretations of it using locally perturbated synthetic data by satisfying a criterion called local fidelity [ ] . local fidelity suggests the explanations should be locally faithful with the model behavior. local fidelity does not imply global fidelity however global fidelity implies local. to increase interpretability simple surrogate models can be trained with local data as it is expected that the response variable varies with the features almost linearly in a local region. in fact, there is a tradeoff between local fidelity and interpretability that needs to be made. model agnostic methods perturbs the input features in a local region around a single or a group of datapoints and feeds the model to obtain predicted response variable. this synthetic data is in turn used to train simple surrogate models to obtain local interpretations of global model. there are several existing methods available in the literature to derive local interpretations of a model [ , , ] . few works also proposed methods to derive global explanations from local interpretations of any black box models [ , ] . similar to as stated in [ ] deriving explanations requires optimization of the following function, where g is set of interpretable surrogate models in a locality, is the global model to be explained, is the distribution function defining the locality of , ℒ is the loss function and is the complexity of the model . it is desirable to minimize both Ω and ℒ. however, in general they are inversely proportional when the spread of is large. a very small spread of is also not desirable as it will oversimplify g to draw any meaningful explanations in the locality. thus, a choice of is important to derive meaningful interpretations. the locality of is defined by a threshold distance in all directions from both spatially and temporally and it is defined by the following tuple, where and are spatial and temporal components of observation . and are spatial and temporal threshold distances from to the boundary of locality. fig. illustrates spatiotemporal locality of observation . spatial locality is bounded by pixels up to in all direction from such that locality of is bounded by a square box of pixels of size ( + ) x ( + ). no paddings are applied at the edges. thus, perimeter defining locality of pixels at the edges of a frame are trimmed. as illustrated in fig. temporal locality is also defined similarly. combining spatial and temporal locality the local region of observation is defined by a sequence of group of pixels with equal time lead and lag from unless resides on temporal edge of an input tensor in which case temporal locality is trimmed on the direction of the edge. perturbated data points are generated by randomly perturbing the pixel values of following a uniform distribution. perturbated distribution is calculated separately for each feature. the perturbated sample distribution is calculated as following, where ( , ′) is uniform distribution with upper and lower bound as , ′, ( ( )) is standard deviation of all observations in the locality of and randomly selects one sample from two. the spatial features are only perturbated spatially and same values are copied temporally along the corresponding channel. the channels having temporal component are perturbated for different time slice within an input tensor. each perturbated pixel in a time slice represents a separate feature. input tensors are constructed using the perturbated values and passed through the blackbox model to generate a predicted output value. the set of all input perturbated data points of and the corresponding predicted output values serves as the training dataset for the surrogate model . each input channels and the predicted values are normalized to mean and standard deviation prior to training the surrogate model. normalization is done to convert the features into same scale so that coefficients of a linear regression surrogate model gives the relative influence of the features on the response variable. thus, the loss function is defined as following, where the function constructs the input tensor in the original representation from perturbated samples. though can be created by perturbing all features of a pixel in each channel within an input tensor, however in our analysis only a subset of all features is perturbated to produce to find effect of those features on transmission rate. other features are kept constant as per the original observation. is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . intuitively this will explain the effect of the chosen features on the transmission rate in a single pixel area given all other parameters remain constant including feature values of spatio temporal neighboring pixels. in our analysis is created by perturbing the following features only. population density, female fraction, median age, weather at th , th and th time lag. weather includes average daily temperature, -day temperature standard deviation and average daily relative humidity. apart from the weather features the other three features have no temporal component. so, for them the perturbated values are copied temporally in the input tensor during reconstruction. the weather features from th to th time lag is chosen by assuming the average incubation period of sars-cov- between to days. the spatial ( ) and temporal ( ) distance for defining locality is taken as . the perturbated samples for each feature are generated by equation . local interpretations are carried out for each pixel which experienced at least cumulative infection cases on st march . the objective is to deduce the influence of aforementioned features on the transmission rate in each pixel given all other parameters remains constant. perturbated input samples are generated for each pixel. the samples are reconstructed in tensor format and fed to the model to obtain the predicted transmission rate and together they form the input output samples. for each pixel a linear regression surrogate model is trained with the training samples. the coefficients of each feature denote the influence on the transmission rate. fig. illustrated the feature influence chart for different pixels in grid . we choose grid as it experienced highest number of cumulative infection cases with nearly % of total infection cases in usa as of st may . only those coefficients are plotted which have pvalue < . . the features whose absolute value of median and standard deviation across all days are less than . , are considered unimportant and filtered out from the plot. the counties covered by each pixel in grid which have nonzero population is stated in table . the influence values are smoothed using rd degree polynomial. new york & bronx have somewhat positive influence of population density (pop den) and female fraction (f perc) on transmission rate. median age (med age) has positive effect in the mid period and negative on early and later days. th day time lag temperature (t temp) have slight negative effect on later days. on average putnam also have positive influence of population density, median age and female fraction. however, population density and female fraction shows negative influence on later days. th time lag and th time lag relative humidity (t rh & t rh) have slight negative impact on average. at grid level population density and female fraction positively impacts transmission rate on daily basis. median age has minor positive impact on earlier days and negative impact on later days . fig d. shows median of influence across all days for different pixels in grid . population density and female fraction have positive impact across all pixels. median age closely resembles a sinusoidal curve which implies that its influence varies widely across pixels. fig. illustrates the global effects of the features on transmission rate. to generate global interpretations local surrogate models are built for each pixel with perturbated samples. for each feature the distribution of influence values for all pixels with nonzero population is plotted against time. considering the median of the distribution, population density, female fraction has positive impact across all days whereas median age has negative impact. temperature has minor positive impact, temperature standard deviation has minor negative impact and relative humidity barely have any noticeable impact on transmission rate. from this study it is clear local influence of features at pixel and grid level may widely deviate from global average. this is important as spread of infection is highly skewed regionally such that few hotspots contribute majority of the infection cases. thus, studying the local influence of features can shed light on the local dynamics of spread and at the same time global influence charts provides a general idea of the influence on spread. classical sir model assumes a constant transmission rate and it typically predicts a smooth bell curve of active is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint infection cases with respect to time with a single peak. however, transmission rate may vary with respect to multiple external factors including intervention methods like lockdown. a variable transmission rate may result in periodic subsidence and resurgence of the spread of infection and in turn producing multiple peaks of active infection cases along time. along with this the recovery rate may also change due to multiple intervention methods like enhancing hospital facilities, improving treatment procedure etc. as shown in equation , recovery rate is very important in achieving disease free stable equilibrium state. in general, the average removal rate (recovery rate + death rate) over a period should exceed average transmission rate in order to reach the disease-free equilibrium. considering the death rate to be constant and quite small compared to recovery rate of covid- , the time required to reach the equilibrium state is inversely proportional to the difference between recovery rate and transmission rate. in our experiments we used the trained model to do long term forecasting of the epidemic with current normal parameters and compared with an "what if" analysis by modifying the removal rate. a days forecasting is carried out for the grid . since weather features barely impacts transmission rate in grid thus the model trained without weather features is used for forecasting. "what if" analysis is done by setting high removal rate to expedite disease-free equilibrium and compared with current normal forecasting by setting removal rate as running average of past days. in "what if" analysis removal rate is set as per equation by setting t = with upper hard limit . . as removal rate changes daily active infection cases which in turn impacts future transmission rate and due to upper hard limit of removal rate the value of in some pixels is less than upper bound calculated by equation . from fig. a and b it is evident that number of active infection cases reduced much faster in the "what if" analysis and most of the pixels hit near baseline state at least once within -day period. however rapid periodic resurgence of the disease is seen in this case. as recovery rate has upper hard limit thus in some cases resurgence with high transmission rate resulted in destabilizing disease-free equilibrium. the growth is again quickly dampened due to high recovery is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . rate in future periodic resurgences. this can be empirically explained by the fact that population gets cautious and maintains social distancing with low intermixing when infection cases are high and vice versa. fig. c and d suggests there is rapid periodic resurgence of new infection cases in "what if" analysis compared to current normal and multiple short low new infection periods are seen. the resurgences in some cases (pixel , ) are stronger compared to current normal. thus, it is evident, by only increasing recovery rate abruptly, infection spread may not be controlled fully unless other intervention methods are adopted to prevent spike of transmission rate during resurgence periods. fig. a and b shows the plot of daily active infections when only pixel and are subjected to modified recovery rate respectively and other pixels are set with current normal recovery rate. in both the cases there is a quick dampening of active cases in and pixels and resurgence spike is shorter and weaker compared to fig. b . it is evident there is spatial influence of neighboring active cases and transmission rate. one explanation can be, isolated intervention measures to dampen the spread does not breaks the cautiousness and preventive measures among the population. this makes determining an ideal recovery rate for a region a complex optimization problem. fig. shows active infection cases at grid level quickly reaches baseline in "what if" scenario compared to current normal, but it is not eradicated fully. there are also small periodic spikes in future. the current normal scenario suggests unless strict intervention actions are not taken to reduce transmission rate or recovery rate it is going to take long time to reach the baseline. the trace of new infection cases suggests the trend is quite similar in both the scenarios with more frequent and stronger spikes in "what if" scenario. in current normal scenario the model estimates new infection cases and removed cases in -day period. in "what if" scenario it estimates new infection cases and removed cases. however, fig. c suggests most of the removal happens in initial days of forecast period due to abrupt increase of removal rate in forecast period. in real world such abrupt increase of removal rate may not be possible. however, on an average if the difference between removal rate and transmission rate can be maintained as per equation it is possible to dampen the spread of infection within desired time period. though in our analysis we took removal in strict sense however it may not refer to complete recovery. identification and complete isolation of a patient such that there is negligible chance of further spread of the infection from the patient may also be referred to removal. thus, maintaining high recovery rate, rapid and strict isolation of infected patient and intervention methods to reduce transmission rate are the keys to rapid convergence to diseasefree equilibrium. a thorough study on the transmission rate of covid in usa revealed several insights. key influencers are identified. however, there might be other influencers like human mobility, demographics, government interventions etc. on availability of those feature data, proposed methods may be applied to find influences. these methods can also be applied to other countries. though a threshold condition is derived for disease free equilibrium, yet it is not straightforward to determine ideal recovery rate to rapidly dampen the infection spread due to complex dependency of transmission rate. a general solution method may be investigated to solve this optimization problem and come up with ideal regional recovery rate. is the author/funder, who has granted medrxiv a license to display the (which was not certified by peer review) this preprint the copyright holder for this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint containing papers of a mathematical and physical character qualitative analyses of communicable disease models influence of nonlinear incidence rates upon the behavior of sirs epidemiological models nonlinear biological dynamics system a delayed epidemic model with pulse vaccination. discrete dynamics in nature and society regulation and stability of hostparasite population interactions: i. regulatory processes analysis of a delayed sir model with nonlinear incidence rate. discrete dynamics in nature and society dynamic analysis of an sir epidemic model with nonlinear incidence rate and double delays a simple sis epidemic model with a backward bifurcation infectious disease models with time-varying parameters and general nonlinear incidence rate on the final size of epidemics with seasonality estimation of time-varying transmission and removal rates underlying epidemiological processes: a new statistical tool for the covid- pandemic temperature and latitude analysis to predict potential spread and seasonality for covid- modelling and prediction of the coronavirus disease spreading in china incorporating human migration data convolutional lstm network: a machine learning approach for precipitation nowcasting us covid- daily cases with basemap investigating causal relations by econometric models and cross-spectral methods. econometrica: journal of the distribution of the estimators for autoregressive time series with a unit root the vanishing gradient problem during learning recurrent neural nets and problem solutions lstm can solve hard long time lag problems from local explanations to global understanding with explainable ai for trees. nature machine intelligence explaining the predictions of any classifier how to explain individual classification decisions anchors: highprecision model-agnostic explanations model agnostic supervised local explanations artificial intelligence forecasting of covid- in china analysis and forecast of covid- spreading in china, italy and france a deep residual network integrating spatial-temporal properties to predict influenza trends at an intra-urban scale us covid- daily cases with basemap : an overview of the global historical climatology network-daily database climate reference network after one decade of operations: status and assessment a multivariate spatiotemporal spread model of covid- using ensemble of con-vlstm networks key: cord- -c ne n l authors: zhang, haoqian; basescu, cristina; ford, bryan title: economic principles of popcoin, a democratic time-based cryptocurrency date: - - journal: nan doi: nan sha: doc_id: cord_uid: c ne n l while democracy is founded on the principle of equal opportunity to manage our lives and pursue our fortunes, the forms of money we have inherited from millenia of evolution has brought us to an unsustainable dead-end of exploding inequality. popcoin proposes to leverage the unique historical opportunities that digital cryptocurrencies present for a"clean-slate"redesign of money, in particular around long-term equitability and sustainability, rather than solely stability, as our primary goals. we develop and analyze a monetary policy for popcoin that embodies these equitability goals in two basic rules that maybe summarized as supporting equal opportunity in"space"and"time": the first by regularly distributing new money equally to all participants much like a basic income, the second by holding the aggregate value of these distributions to a constant and non-diminishing portion of total money supply through demurrage. through preliminary economic analysis, we find that these rules in combination yield a unique form of money with numerous intriguing and promising properties, such as a quantifiable and provable upper bound on monetary inequality, a natural"early adopter's reward"that could incentivize rapid growth while tapering off as participation saturates, resistance to the risk of deflationary spirals, and migration incentives opposite those created by conventional basic incomes. a well-functioning free market rewards the providers of valuable products and services, encourages innovation through competition, and limits waste by financially starving ventures that fail to produce value. but today's free markets embody at least two long-term sustainability problems: they allow uncontrolled increase in inequality [ ] , and they cannot function without constant growth [ , ] . for centuries, philosophers and economists have proposed ways in which the concept and function of money might be improved or redesigned to be more stable, equitable, and sustainable [ , , ] . permissionless cryptocurrencies, however, offer us the unprecedented opportunity not only to envision on paper a "clean-slate" redesign of money, relatively unconstrained by either the economic status-quo or risk-averse governments, but also to implement alternative monetary designs and experiment with them circulating in real-world communities. popcoin is a cryptocurrency project aiming to prototype and eventually launch a more democratic, equitable, and sustainable form of money. today's "democratic" societies and organizations typically attempt to satisfy the democratic principle of equality only in terms of governance, via "one person, one vote" in decision-making. popcoin, in contrast, pursues democratic equality in three dimensions: governance, operation, and economics. governance equality means "one person, one vote" in decision-making, as usual. operational equality in popcoin means "one person, one unit of stake" in securing consensus and maintaining a shared history or blockchain [ ] . finally, economic equality in popcoin means ensuring all participants equality of opportunity to employ money -and the community resources it represents -towards personal and collective goods. this paper focuses on the third objective of economic equality: the others, while equally important challenging, we leave for other work to address. motivated by supporting sustainable and equitable economic opportunity while retaining capitalistic rewards for valued work and innovation, popcoin regularly mints and distributes new money to all real human participants. the basic goal of popcoin's monetary policy is to ensure that these "basic income" distributions provide all participants a baseline of economic opportunity that is equitable, continuous, and unvarying in both space and time. equality over "space"i.e., population -means guaranteeing each participant an equal share in each distribution of new money. equality over time means the value of each basic income distribution represents an equal and constant proportion of the community's total monetary resources. most critically, the basic income's proportionate value and utility must not diminish from one month, year, or generation to the next. this paper's first main contribution is a preliminary "long view" economic model and analysis of what a sustainable, democratically egalitarian form of money might look like, if it were eventually to become widely-adopted as the predominant currency within a community of sufficient critical mass. our analysis adapts existing tools from economic theory to develop popcoin's monetary policy and identify several interesting properties. first, in line with precryptocurrency ideas such as gesell's freigeld [ ] and universal basic incomes [ , ] , popcoin decouples broad economic growth from debt by giving all participants a regular supply of debt-free money. second, popcoin's design imposes a readilycalculable upper bound on inequality in the distribution of popcoin among participants after each minting, thereby ensuring a form of sustainability in terms of basic financial inclusion, contrasting with classic currencies where inequality can increase without bound. third, while increased real growth can create monetary deflation by increasing demand, popcoin appears to mitigate the classic risk of "deflationary spirals" -where high demand yields higher real interest rates and hence borrowing costs, making money even more scarce in a positive feedback loop. because popcoin's basic income is not debt-based, higher demand on popcoin raises the basic income's real value without affecting its broad avail-ability to participants, and may counteract deflation by giving all participants both opportunity and purchasing power to spend or invest. while this long view is promising, real currencies are not isolated but inhabit a larger economic ecosystem. this paper's second main contribution is a preliminary exploration of several intriguing properties we may expect of a permissionless cryptocurrency embodying popcoin's monetary policy. first, a preliminary exchange rate analysis suggests that we may expect popcoin to increase gradually in value over time with respect to an inflationary fiat currency like usd, assuming that both the size and spending behavior of the popcoin community is stable in certain respects. we don't actually expect either of these factors to be stable in practice, however, especially while a popcoin community is small and rapidly-evolving, leading to a second key observation. because basic income represents a fixed fraction of total popcoin supply divided by participant population in that minting, earlier participants in a growing community receive a larger fraction of total supply in earlier mintings. this effect might serve as a natural "early adopter's reward" -and an incentive for participants to promote popcoin and grow the community -that automatically tapers off as participation saturates and stabilizes. third, while we may expect speculative trading and "hodling" of popcoin to yield wild exchange-rate swings as with other cryptocurrencies, popcoin continually "taxes" speculative holdings and redistributes value to participants' basic incomes, which may both disincentivize too much speculative holding and reward participants for weathering speculative storms. nevertheless, we prove that a rational participant may save some of his income to increase his future utility, and the rich would pay more demurrage fee than the poor, even though they are subject to the same mechanism and global demurrage rate. fourth, because popcoin represents a permissionless and borderless community, its basic income floats to some single global value versus other currencies, rather than being defined by policy within a jurisdiction as in a conventional basic income. popcoin's basic income will therefore buy more and feel more useful in poor countries with low cost-of-living than in rich ones, it will gradually redistribute wealth from the latter to the former, and any "migration incentive" it creates will be from rich countries to poor: opposite the poor-to-rich migration incentives that a conventional ubi would contribute to. this initial development of popcoin has many limitations, of course. it focuses only on monetary policy, leaving operational and governance issues out of scope. our preliminary economic analysis, detailed in the appendices, makes many simplifying assumptions that may prove unrealistic, and our formal model currently covers only a subset of the interesting properties of popcoin that we identify and explore intuitively. further, because popcoin as developed here effectively "taxes" only money and not non-monetary wealth such as real estate and investments, it inherently incentivizes spending over holding. this may be desirable to stimulate economic activity as gesell proposed [ ] -but it may also make other currencies and non-monetary wealth more attractive as investements, limiting the total value we can expect popcoin to acquire, and similarly limiting its potential to address inequality in general across all forms of wealth. indeed we expect, and accept, that popcoin may not appeal much to economically "greedy" users, but mainly to those motivated more by social, political, or sustainability goals. we leave these limitations to be addressed in future work. democracy, or literally rule by the people [ ], has no single definition but embodies widely-held principles. the council of europe boils democracy down to two key principles: individual autonomy -that "people should be able to control their own lives (within reason)" -and equality -that "everyone should have the same opportunity to influence the decisions that affect people in society" [ ] . political philosopher robert dahl defines criteria essential to democracy, among them equal opportunity to obtain "enlightened understanding" of the issues, to control the agenda, to participate in discussions, and to vote on decisions [ ]. we normally interpret "equality" only as political equality in self-governance. among the "decisions that affect people in society", however, classical economics carves out a huge swath -namely, almost all decisions on allocating society's resources -in which inequality rules. we have mostly exempted money from the democratic principle of equality: those with more money can spend proportionally more on what they like, hire more labor to help them, invest more in ventures they support, etc. with inequality exploding [ ], leaving % of incomes stagnant as $ . trillion was transferred to the top % since [ ], current trends toward unlimited inequality represent a clearly unsustainable path. furthermore, economics and governance are inseparable in practice: "money is power." more money buys more influence [ ] -whether via advertising, lobbying, or online bot farming [ ] . for the growing global "precariat" [ ] struggling to survive on stagnant incomes from multiple uncertain sources, finding the time even just to vote -let alone fulfill dahl's democratic criteria of "effective participation" and "control of the agenda" based on "enlightened understanding"feels increasingly like a distant luxury only the rich can afford. in numerous ways, economic inequality corrodes political equality and undermines democracy. irving fisher noted the unsustainability of uncontrolled economic inequality, and its corrosion of political equality, after the conclusion of world war i in his annual address as president of the american economic association: our society will always remain an unstable and explosive compound as long as political power is vested in the masses and economic power in the classes. in the end one of these powers will rule. either the plutocracy will buy up the democracy or the democracy will vote away the plutocracy. in the meantime the corrupt politician will thrive as a concealed broker between the two. [ ] political and economic philosophers alike often support the principles of inclusion and equal opportunity. even capitalist economics generally presumes that participants compete on a fair and "level playing field" even if outcomes mayand arguably should -be highly unequal. among the opportunities most people want are the opportunities to earn economic rewards for hard work, innovation, or wise investment. for these purposes, we cannot realistically pretend that everyone is equal in either abilities or motivation. but if we accept that allowing (equal) opportunity to earn rewards necessitates allowing inequality in economic outcomes, this does not mean we must or should accept unlimited inequality. classical monetary policy is driven primarily by stability concerns: particularly stable prices, to protect money's functions as a unit of account and a store of value, and a stable money supply to drive commerce [ ] . even at this modest goal of maintaining a stable "status quo," however, classical economics fails miserably, yielding frequent "boom-and-bust" cycles that show no signs of abating [ ] . but as bitcoin [ ] and the countless cryptocurrencies it inspired have underlined, money is not only a social good but a technology that can be designed, and some designs will serve us better than others. we now have the opportunity not only to rethink but also to implement and deploy new forms of money without anyone's permission. money can now be created electronically by ordinary individuals, not just by banks. and even wildly-unstable digital currencies can capture tremendous interest and enter widespread use. the central idea motivating popcoin is the radical question of whether in focusing single-mindedly on stability, classical economics got its basic priorities wrong? stability is great when we can get it, but a stable march towards global economic (and environmental) destruction is eventually just as disastrous as an unstable march to the same end. could we design, implement, and deploy a form of money that instead pursues sustainability and equal opportunity as its primary goals, with stability as a still-desirable but subsidiary objective? the design space of cryptocurrencies and monetary policies is clearly rich and infinite, so we cannot expect to find any unique or best "answer" to the above challenge. but could we find some relatively simple monetary policy that plausibly achieves these goals under arguably-realistic assumptions -ideally a policy we can encode into a few simple rules that a cryptocurrency can enforce automatically? classical economic theory calls for constant guidance from central banks to maintain a semblance of economic stability. could we find a "hands-free" rule-set with the potential to avoid at least the most destructive instabilitiesnamely positive feedback loops such as overheating or deflation spirals -while ensuring equal opportunity in some formally definable fashion? in popcoin we develop two simple rules that appear particularly promising in combination. the first rule is that all participants regularly receive an equal supply of newly-minted money as a baseline foundation for economic opportunity, which we refer to as equal opportunity in "space". this rule relates closely to the increasingly-popular idea of basic income [ , ], but expressed in monetary rather than a purely social policy -a distinction that yields important differences we explore later in section . the philosophical grounds for an equal supply of basic income is clearly to support equal opportunity, a justification often debatably ascribed to john locke [ , , ]. our justification for a regular supply is to ensure that support for equal opportunity remains inclusively available for life in the face of personal losses from risk-taking, accidents, disasters, etc., as discussed further in appendix a. . the second and less-precedented rule underlying popcoin is that the portion of total money supply distributed equally to all participants must be constant at each distribution, in particular not diminishing with time, summarized as equal opportunity in "time". basic income proposals typically rely on a policy decision to choose some "appropriate" value that somehow balances standardof-living expectations against fiscal budgeting constraints. but the "right" balance between expectations and affordability is infinitely debatable and subject to change frequently with public and government mood. moreover, any chosen value denominated in an inflationary fiat currency will diminish in real value and effectiveness in time, just as minimum wage protections have eroded [ ] . popcoin introduces the more radical proposition that we simply peg the value of each distribution to a constant fraction of total money supply, chosen and justified on some less-fluid basis, such as the lifetime an average person has to enjoy or re-invest rewards, as discussed in appendix a. these rules work together toward ensuring that the economic opportunity offered by regular distributions of new money is egalitarian in both "space and time": i.e., individually between the participants in any given distribution, and collectively between earlier and later distributions. instead of attempting to support some particular standard of living, popcoin attempts to ensure that all money distributions are fair and proportionate: both individually among the participants in today's distribution, and collectively with respect to the portion of monetary wealth similarly distributed in prior months, years, or generations. this combination of rules supports economic sustainability in two respects. first, popcoin's first rule ensures that all participants have an equal and inalienable source of debt-free income, which could break the economy's reliance on constant growth to achieve broad-based increases in living standards as discussed in appendix a. . second, popcoin's second rule ensures that one's opportunities today are not dominated by economic wins and losses of the past, and that inequality cannot increase without bound as we explore later in appendix c. while popcoin directly addresses only economic and not environmental sustainability as some proposals do [ ], limiting growth dependance and inequality could reduce pressures that often result in environmentally unsustainable practices and policies. a unit of fiat currency today generally represents an arbitrary unit of value, whose nominal value has no meaning except in relation to perceived real value and to other currencies as it floats through supply and demand. one dollar doesn't "mean" anything. popcoin, in contrast, builds on an idea pioneered by time-based currencies [ , , ]. since money is so commonly used to trade peoples' time in providing labor and services, why not define the a currency's value in terms of a person's time? time is an inherently-stable reference point, whose advance we can quantify precisely in terms of other physical phenomena, as atomic clocks do. time is also inclusive and democratically egalitarian, in that everyone living inherently receives a constant "supply" of time at the same rate as others -ignoring space travelers at relativistic velocities for now. imagine a purely-fictional world in which all people spend eight hours each day supplying services to someone else, eight hours per day consuming the services of others, and eight hours per day sleeping. further suppose that all work consists solely of unspecialized services that anyone can perform, like sitting with someone to keep them company, so that one hour of anyone's time is worth exactly as much as an hour of anyone else's. then the only need the inhabitants have for "money" is to negotiate which hours each person spends working (and for whom), consuming services (from whom), or sleeping. in this fictional world, one popcoin would represent exactly one hour of anyone's time. we make no pretence that this fictional world models reality, but treat it merely as an "ideal reference" against which we may treat complex reality as a (large) set of adjustments, the cumulative effects of which we let supply and demand reveal dynamically. since not everyone's time is equally valuable, for example, a specialist whose time is five times more sought-after than that of a fully-unspecialized worker would find herself able to charge five popcoins per hour, all other factors corresponding to the ideal reference. we similarly expect the trade value of a real popcoin to deviate from the ideal for myriad other reasons: e.g., people like to work only five days per week and take holidays; participation changes due to people adopting or leaving popcoin; people also use other currencies competing with popcoin; investors artificially increase popcoin scarcity by hodling it and thereby keeping it out of commercial circulation; usage changes and shocks in other economically-linked currencies affect popcoin indirectly; ad infinitum. while accepting that reality is fluid and far too complex to analyze all the factors, nevertheless the ambition is that one popcoin should always conceptually "mean" something with respect to peoples' time, should do so equitably, and should mean the same thing in a decade or a century as it does today. we can now specify the popcoin monetary policy concisely in terms of the pseudocode in algorithm . this algorithm is concerned only with what happens at each regular minting, and assumes that wallets and normal trading between mintings are handled by standard (e.g., bitcoin-like) transaction processing. in brief, at each minting the algorithm (a) determines the new number of participants at time t, (b) redenominates the currency to account for participation changes, (c) applies demurrage to current balances to keep total supply constant, and (d) issues a constant b new popcoins to each participant. we briefly unpack and informally justify each step below. because we want one popcoin to represent one hour of unspecialized work in the ideal reference world above, and each of the n t participants at time t have an inherent supply of b work-hours of time per minting period, total popcoin supply must depend on -and be proportional to -participation. to account for participation being non-constant in a real permissionless cryptocurrency, algorithm effectively redenominates the currency in step (b) whenever participation changes. that is, the algorithm simply scales all existing wallet balances by the factor n t /n t− to convert the last time period's currency -appropriate for n t− participants -into a "new currency" appropriate for n t participants. to ensure that algorithm can issue each participant a fixed number b of new popcoins per minting in step (d), while also ensuring that the total value of all newly-minted currency represents a fixed fraction α of the currency's total supply as discussed in section . , we must demurrage all existing wallet balances in step (c) by the factor of − α. this demurrage ensures that total popcoin supply at time t asymptotically approaches but never exceeds bn t /α. redenominating a conventional currency with printed banknotes is of course an expensive process typically done only rarely after periods of inflation [ ]. demurrage is similarly nontrivial with printed banknotes -a purpose for which gesell [ ] invented the clever idea of stamp scrip, where the holder of a banknote must purchase and periodically affix stamps weekly in order to keep the banknote valid [ , ] . redenomination and demurrage are straightforward in principle for a bitcoin-like cryptocurrency, however, where all wallet balances reside on a shared ledger. we may worry that currency users may be confused and concerned on seeing their nominal wallet balances change periodically -but this already happens with conventional bank accounts when maintenance fees are charged, interest is deposited, etc. further, the implementation-efficiency issue of regularly updating all wallet balances is readily addressed by internally the ratio of newly issued popcoin to total supply. denominating wallet balances in an inflationary and participation-independent "hidden currency" like poplets as discussed in appendix g. simplistically assuming one minting per year, we would set b = . × = to reflect the ideal reference model above in which one popcoin represents eight hours of unspecialized work per day. the fraction of total supply demurraged and redistributed at each minting, α, is similarly somewhat arbitrary but might reasonably be set to %, giving popcoin a -year "tenure" corresponding to around a modern human working lifespan as discussed in appendix a. . we now introduce an economic model built on methods typically used in monetary policy by central banks and other cryptocurrencies. we then express the principles of popcoin in this model: fixed basic income, equality over population and equality over total supply. finally, we derive popcoin's monetary policy from these principles alone and argue that popcoin's monetary policy is both necessary and sufficient to fulfill them. monetary policies, whether directed by central banks or encoded in cryptocurrency code, are generally built on two methods to control the money supply: adjusting interest rates and directly distributing money. our economic model incorporates both of these methods. table . summarizes the notation we use subsequently throughout this paper. " more frequent mintings, likely more practical, just require adjusting the constants. interest-rate driven monetary policy used to be the most effective standard tool used by central banks. as interest rates plummeted to zero, however, central banks have had to adjust money supply more directly, either through quantitative easing or by directly handing "helicopter money" to spenders [ ] . cryptocurrencies like bitcoin and ethereum, in contrast, generally do not have the concept of an interest rate: they solely rely on block rewards as their mechanism to inject money and increase the money supply. on a micro level we assume a world with n t participants during a time period t, where t ∈ n. we denote by x i t the balance at the end of period t for any participant i, i = , , . . . , n t . naturally, x i t carries into the next period t + , as savings that potentially yield interest. our model assumes the interest on savings as part of the income of any participant during each period of time. we further denote by r i t the interest rate on savings of participant i from period t − . in addition, a participant i also generates the following two types of income at the beginning of any time period t: (a) the basic income b i t distributed to each participant, and (b) the earned income, denoted by in i t . participant i's balance may accumulate over time i.e. where out i t denotes the expenditure of participant i in period t. on a macro level we assume that both basic income and positive interest income are freshly-minted, i.e. created by the monetary system purely numerically -instead of relying on any social entity such as a government or philanthropist, or by compelling one into debt. these are the only two methods to mint new coins. similarly, we assume that the negative interest simply "disappears", which leads to a reduction of the total currency supply. therefore, the net change of the total supply becomes the sum of all participants' basic income and interest in the currency: or -on a macro level -we write: where m t denotes the total supply at the end of period t, and d t denotes the sum of total basic income distributed in period t. the aggregate interest rate for all participants, unique in any period t, we denote by r t . the principles of achieving equal opportunity in both "space and time" from section . define the key policy constraints defining popcoin. we therefore abstract these principles into the following three mathematical equations representing popcoin's fundamental principles: (i) the principle of fixed basic income. because popcoin is a time-based currency, each participant periodically receives the fixed nominal amount b of basic income as introduced in section . above, where b i denotes the basic income of participant i. (ii) the principle of equality over population. because basic income is intended to support equal opportunity in popcoin, its amount must be the same across all participants. we denote this universal amount as b, i.e., where i and j denotes two different participants. we therefore obtain the total amount of newly issued popcoins as: (iii) the principle of equality over total supply. popcoin achieves equality across time and generations by setting the total amount of newly issued popcoin to be a fixed proportion of the existing popcoin supply, i.e., with α a constant system parameter. appendix a. discusses how we might choose the value of α. adopting all principles (i)∼(iii) uniquely determines the monetary mechanism of popcoin; any change to the mechanism would refute at least one of its principles. in the following, we derive the mechanism of popcoin step by step from a strawman case with a constant population size and money injected through basic income, but no interest rate, to a simplified scenario that allows for interest rate, and finally to a general situation with varying population size. strawman: fixed population, basic income and zero interest. with a fixed number of participants, principles (i) and (ii) set the total basic income distributed in each period to a constant, according to eq. ( a). under a zero interest rate setting over all time periods like bitcoin and ethereum, the total amount of popcoins would grow linearly: this would violate principle (iii), however, in that the issue-to-supply ratio (eq. ( b)) would decrease over time as a result. simple case: popcoin with fixed population. by this reasoning, with constant participation, principle (iii) can be maintained only under a negative interest rate, i.e. r t = −α. we substitute d t in eq. ( ) by its form in eq. ( b). under the negative interest rate −α, the total currency supply over time becomes: a negative interest rate or demurrage devalues existing coins gradually over time [ ] . in this case, the demurrage rate is exactly α. general case: popcoin with population changes. now consider the general case with population changes. we denote by n t the population growth rate in period t, such that n t = ( + n t )n t− . by eq. ( a), the total amount of newly issued popcoin, or d t , grows at the same rate: solving the system of eq. ( ), eq. ( b) and eq. ( ) for the interest rate, we obtain r t = ( + n t )( − α) − . total currency supply now takes the following form: this matches our algorithm that existing popcoins scaled by the factor of ( + n t )( − α) with new basic income distributed to every participant. popcoin supply grows proportionally to the population size we denote µ t as the growth rate of popcoin, we have: this equation can be clearly presented from the relationship between the currency supply and the population size, implied by the combination of eq. ( a) and eq. ( b), i.e., and it is not hard to verify that it is consistent with popcoin's monetary policy shown in eq. ( ). preliminary analysis of the above model leads us to a number of interesting observations about popcoin, as detailed in the appendices and summarized here. these analyses of course make many simplifying assumptions and cannot hope to model all the complex factors relevant in reality, but they allow us to tease apart some broad effects and trends. bounded inequality. popcoin's most important property from a sustainability perspective is that it establishes an upper bound on inequality, at least in terms of monetary wealth denominated in popcoin. appendix c shows that after each basic income minting, popcoin ensures an upper bound in three inequality metrics: gini coefficient, variance across all participants' balances, and ratio between any two balances. limiting inequality in monetary wealth alone this way would not, of course, necessarily bound inequality in general across all forms of wealth, even in a hypothetical population that used only popcoin as money. nevertheless, to the degree that having access to money with which to engage in commerce and seek to improve one's fortune is a key element of economic opportunity in practice, popcoin might ensure that this social good and driver of opportunity at least cannot become too unevenly divided over time. adoption incentives. when participation grows more quickly than the demurrage rate of α, popcoin's monetary policy offers a natural "reward" to early adopters -along with an incentive for early adopters to promote popcoin and further increase adoption. suppose the number of participants doubles in some period t, for example, so n t = n t− . then the basic income b that an early adopter received at time t − will, after redenomination for the population change in algorithm , have a nominal value of b at time t before demurrage. the early adopter's saved basic income from time t − , therefore, is effectively worth almost two basic incomes at time t. this does not mean that the real value of these savings necessarily doubles correspondingly, of course. but if the new adopters put the currency in active use and circulation similarly to the existing users, thereby growing the real popcoin economy roughly proportionally as well, then the early-adoption reward will also be meaningful in real value. these effects will naturally create speculation incentives while population and/or currency usage is rapidly evolving. rational investors who correctly predict at time t − that participation will double by t, for example, may be willing to buy popcoin from other participants at t − for close to twice what they expect it to be worth at t, precisely to take advantage of the early adopter's reward. speculation may well create wild swings in popcoin's trade value, just as with other cryptocurrencies. but recall that popcoin's primary goal is long-term fairness and equitability, with stability only a subsidiary goal, as discussed in section . . as popcoin gradually saturates some population of receptive users, the early-adoption reward tapers off and disappears as participation stabilizes, leaving demurrage as an incentive to spend rather than hold popcoin. we leave the mathematical definition in appendix b. exchange rate analysis. a preliminary exchange rate analysis in appendix d, both long-run and short-run, indicates that popcoin would gradually appreciate with respect to inflationary fiat currencies assuming other factors remain stable. for the long-run analysis, we assume that price is flexible and purchasing power parity holds [ ] . the short-run analysis yields a similar conclusion, together with the expected exchange rate overshooting phenomenon [ ], under the assump-tion that prices are sticky and uncovered interest parity holds [ ] . in summary, the fact that popcoin's money supply is constant -though continually-renewing via basic income distributions and demurrage -should keep popcoin ultimately "anchored" in its relation to time as discussed in section . , as fiat currencies gradually drift via inflation. purchasing power analysis. appendix e employs classical inflation theory [ ] to analyze the purchasing power of popcoin. we find that popcoin's purchasing power may be expected to increase in the long run, resulting in deflation, whenever real economic growth exceeds population growth. while deflation is deadly in classical economics, this is because of the dependency of economies on debt-based money creation. monetary scarcity increases the real interest rates, which disincentivizes borrowing and spending, which makes money even more scarce. we argue in appendix e that because new popcoin is created via debtfree basic income rather than loans, deflationary spirals are unlikely to occur popcoin even in the presence of deflation. our exchange rate and purchasing power analyses are currently based on the assumption that popcoin has saturated a fairly large community. we do not expect this assumption to hold in a rapid-growth early phase development of popcoin, however. we speculate that as users adopt popcoin so that more and more goods and services can be purchased with popcoin, its exchange rate and purchasing power with respect to other currencies would increase. we have not yet modeled this scenario, however, a task we leave to future work. speculation and saving analysis. appendix f analyzes how a rational individual would behave with respect to saving or speculative hodling of popcoin versus spending for productive use. due to the early adoption reward mechanism discussed above, speculation on popcoin is likely to happen in early stages, potentially making the currency unstable but also attracting more users. however, after popcoin has successfully saturated its potential user base, speculation is subject to tax via demurrage and therefore is disincentivized. nevertheless, we find that the rich might still save income to improve utility -thereby paying higher tax rates than the poor -even though a consistent global demurrage rate is applied to everyone. thus, we by no means expect speculation or savings to disappear even once participation in popcoin stabilizes. to the extent it continues, however, all participants are effectively compensated for any resulting instability via the tax-and-redistribution effect of demurrage and basic income. stability versus equitability. a central bank's primary mission is to maintain price stability, traditionally by monitoring real economic indicators and using a variety of policy levers to target about % inflation [ , ] . stablecoins [ , ] are cryptocurrencies that similarly pursue stability, typically by pegging their value to that of a traditional currency -and hence indirectly relying on that currency's underlying central bank. all of these (direct and indirect) stabiliza-tion techniques depend on complex economic monitoring and adjustment mechanisms, none of which have yet proven stable in fact over historical periods [ ] . popcoin follows bitcoin's audacity of adopting an "automatic monetary policy based solely in nominal data" [ ] . this choice makes popcoin's policy attractively simple, while carrying the the immediate implication that -like bitcoinwe cannot expect popcoin to exhibit price stability with respect to real economic activity in the way that central banks and stablecoins aim to. the dynamic controls that would be necessary for conventional price stability, in fact, appear incompatible with popcoin's mandate of equitability in space and time, at least as modeled above in section . . adjusting the demurrage rate α to track economic indicators would mean that the aggregate basic incomes distributed at some times must represent a different proportion of total monetary wealth than the aggregate basic incomes distributed at other times, hence potentially eroding one generation's economic opportunity versus another. thus, the choice between price stability and equitability as a currency's "prime directive" may represent a fundamental and in some sense irreconcilable difference. nevertheless, an intriguing question for future exploration is whether a currency like popcoin might achieve a different form of stability in the long run: e.g., if its user population grows sufficiently large, if that population's demand for popcoin (e.g., the average "basket of goods") becomes sufficiently stable in a human behavioral sense, and if demurrage limits inequality and disincentivizes speculation sufficiently to ensure that popcoin's long-run real value mostly reflects relatively-stable aggregate human behavior of the population and not the speculative sentiments of commercial banks and rich investors. we leave this fascinating question of what "stability" really means for future exploration. migration incentives. finally, while so far only based on informal analysis, we observe certain striking differences between the borderless, permissionless basic income in popcoin and a conventional basic income proposal implemented as a fiscal policy in some government jurisdiction. conventional basic income proposals not only require making difficult choices about what level of basic income is "affordable" balancing standard-of-living expectations against budget constraints, but also can create resistance from the fact that they incentivize to "inward migration" towards jurisdictions that have (larger) basic incomes, potentially exacerbating already-inflamed divisions and "fortress" mentalities. the basic income embodied in popcoin, in contrast, promises only equitability rather than any particular standard of living -but also ensures that its reward for participation is borderless and available anywhere popcoin can be adopted. further, because popcoin's basic income will trade at the same value against other currencies anywhere, its purchasing power will be greater in poorer regions with lower cost-of-living. if popcoin creates any migration incentives at all, therefore, they will be from richer to poorer jurisdictions, thereby potentially addressing one significant perceptual roadblock to ubi adoption. popcoin may be considered a digital community currency [ , ], intended as an experimental tool to support commerce and economic empowerment among users who voluntarily opt into using it. gesell's demurrage ideas [ . while security implementing decentralized proof-of-personhood without compromising privacy remains a critical unsolved problem, it is orthogonal to and out of the scope of this paper. popcoin is a cryptocurrency that aims to prototype a more democratic, equitable, and sustainable form of money. popcoin introduces three principles to achieve its goals: fixed basic income, equality over population, and equality over total supply. through regular distribution of freshly-minted coins as basic income to every participant, popcoin bounds inequality across the population. through a small demurrage rate of - % that slowly devalues each coin, popcoin controls the money supply and limits the lifetime of money, bounding inequality across generations. using established economic models, our analyses on inequality, exchange rate, purchasing power, speculation and saving show the potential effectiveness and sustainability of popcoin's monetary policy. this section discusses further issues and considerations justifying popcoin's design principles, which were omitted from the main paper due to lack of space. a. debt, economic growth addiction, and free money it has been said that "gold is the only financial asset that is not someone else's liability" [ ] . in our current banking system based on fiat money, both central and commercial banks can create money by issuing debt. fiat money thus always represents a liability to someone in the economy. when a central bank expands its balance sheet by purchasing assets such as government bonds or private debts, the resulting money is the central bank's liability. commercial banks also create money "out of thin air" by issuing loans [ ] . when a commercial bank lends money to a borrower, the bank creates assets and liabilities simultaneously, thereby creating new money, which is a liability of the commercial bank. fiat money therefore consists essentially of "iou"s: any debt-based dollar existing in the economy implies that someone will have to pay back this dollar, generally with interest, sometime in the future. because the money needed to pay the compound interest on each loan has not (yet) been created at the time the loan is issued, however, we collectively face a "grow or die" problem: the economy must perpetually grow in order for enough debt-based money to exist in the future for all borrowers to have any chance of paying off all the interest on loans issued now. if the economy fails to grow rapidly enough to cover the compound interest demanded on all existing loans, then some of those loans must default -and in a major financial crisis this often means many loans default [ , ] . at its launch, bitcoin [ ] appeared to create a remarkable new exception to the above rule. "anyone" could mine new bitcoin -akin to mining gold -without incurring debt or creating a liability for anyone. it is unclear to what degree this exception to the money-is-debt rule still holds, now that mining is economically infeasible for anyone without access to cheap power and the latest mining hardware, and neither are readily available to newcomers without incurring debt or another form of liability [ ] . nevertheless, bitcoin was merely the most recent demonstration that it is possible to create debt-free money without incurring a liability on anyone, as gesell's "free money" theory had predicted [ ] and as partly confirmed in subsequent experiments and analysis [ , ] . although both gesell's stamp scrip and bitcoin arose from other motivations, breaking the unsustainable cycle of economic "growth addiction" from debt-based money may be one of the most important potentials they demonstrate in principle. why should distributions of money to support equal opportunity be regular, and not special "one-time" events for example? as an alternative, condorcet [ ] and paine [ ] proposed in the s a one-time basic endowment at birth or maturity. further, real governments have occasionally even implemented onetime, "more-or-less" equal distributions to "more-or-less" all citizens: e.g., in the voucher privatization programs following the collapse of the ussr [ ] , and more recently in emergency response to . but steady-state economic reality is populated by a mix of people of all ages. people are continually born, coming of age, and dying; people are continually achieving wins and suffering failures and losses. real innovation requires risktaking -people need the opportunity to try something, fail, and start over. onetime distributions can be lost through bad investments, personal disasters such as addictions or other medical conditions, displacement and losses from to war or natural disasters, etc. in general, one-time distributions cannot guarantee people, throughout their lives, the power to start over with the same opportunities they had before a loss. this observation leads us to the conclusion that baseline support must be a relatively continuous -or at least periodic -supply made available to all individuals while still living and potentially able to take advantage of it. an important question is how we might choose the demurrage rate α in pop-coin. we might approach this question on either a philosophical basis or one of pragmatic historical experience. we can find philosophical and moral foundations for demurrage in the fact that many -perhaps most -forms of property ownership throughout history have been time-limited rather than indefinite. most physical goods and capital have inherent time limits on ownership by virtue of being perishable or wearing out: food, materials, equipment, buildings, even land used unsustainably. counteracting money's durability advantage over other goods was a primary motivator for gesell [ ] . for thousands of years, rulers of ancient mesopotamian civilizations including those of sumeria, assyria, and babylon regularly proclaimed acts of misharum, cancelling all debts and freeing debt-slaves empire-wide, for economic renewal and protection from encroaching aristocracy [ ] . jewish society encoded such a tradition into its most fundamental laws by requiring a "year of jubilee" every years. modern intellectual property law confers only limited-time ownership. shareholder corporations are fairly exceptional in allowing unlimited-time ownership -but there are strong arguments that firm ownership should not be unlimited, as in proposals for stakeholder tenure [ ] and other stakeholder governance models [ ] . given this ancient and modern precedent alike, it should not seem radical to view money as a social good that society grants an individual possession of for a reasonable period, but not forever. in a cryptocurrency or smart contract, we could certainly implement money that behaves like "leprechaun gold" by suddenly vanishing after a particular lifetime, though doing so would compromise its fungibility by making a coin's real value decrease with age [ ] . but observe that in a hypothetical steady-state "leprechaun gold" economy a fraction /l of all money would vanish and have to be renewed year if each coin lasts for l years. by eliminating /l of the value of all coins each year via demurrage, instead of eliminating all of the value of /l of the coins each year, we achieve the same aggregate rate of devaluation and renewal while preserving the fungibility of coins. since α = /l is the demurrage rate, we can consider the reciprocal of the demurrage rate to be the effective lifetime or ownership tenure of the demurraged coins, even if they "vanish" only gradually rather than instantly. but money is a social instrument used by people to reward people for valued goods and services, and the people so rewarded have limited lifespans in which to enjoy (or further invest) those rewards. there is then reasonable grounds to tie the lifetime of such a reward to a time period something like a human generation or working lifespan: because that is the time in which rewards earned early in a person's life may reasonably be expected to benefit them -rather than their heirs or successors -whether through further investment or spending for enjoyment. a reward that lasts significantly longer will primarily benefit the rewardee's heirs or successors, who will generally have different aptitudes and motivations, and who may be unlikely to produce much (new) value for society from that legacy reward. from an equal opportunity perspective, it is of course unjust for the children of poor families to have their opportunities dominated and limited by the economic losses or other hardships their ancestors faced. but it is also arguably unjust to the children of rich families to be denied ever knowing how much of whatever wealth they accumulate truly reflects their own accomplishments, to be proud of, and how much represents wealth and advantage they inherited purely by luck of birth. thus, just as with a limited-duration intellectual property right, tying the ownership tenure of demurraged money to something comparable a working human lifetime optimizes for conferring most rewards on those who earned it, while allowing and expecting the descendents of both winners and losers to prove themselves on a "playing field" that is, if not completely level, at least not tilted to an unbounded and continually-growing degree either. this is at least one philosophical basis for choosing a demurrage rate of, say, somewhere between % and % per year, corresponding to an ownership tenure period of about a -year modern human working lifespan or about a -year generation gap, respectively. gesell's proposed demurrage rate of . %, though derived from the fact that there are weeks per year, comes out at the upper end of this range. the ancient mesopotamians, whose rulers most often declared misharum on the ascension of each successive ruler -i.e., about once per generation -might be viewed similarly as precedent for the % end of this range, whereas the jewish tradition's -year jubilee cycle would be precedent for the % choice. (granted, both human generations and lifespans were substantially shorter then so the correspondence is shaky and imprecise.) the pragmatic historical basis reflects the experience of modern central banks practicing keynesian economics, in which inflation-targeting serves a purpose closely-related to if not quite identical to gesell's demurrage [ ] . experience seems to be that % has proven a reasonably safe and effective inflation tar-get to steer between the risk of deflationary spirals at the lower end, and risk of overheating leading to hyperinflation or bank runs at the upper end [ , ] . there are also arguments for higher inflation targets of around % [ ] . thus, whether based on a fundamental basis of matching ownership tenure to human lifetimes, or based on the pragmatic economic experience of central banks, demurrage rates in the - % range seem likely reasonable, though there is nothing magical about any particular value. long-term assumption on population changes. we assume that in the long term, once popcoin is widely deployed and adopted within some user population, that population becomes relatively stable. mathematically, that is, in reality, participation in popcoin will not be fixed or perhaps even stable, especially in early phases when we would hope to see rapid adoption. in the long term, however, once popcoin has saturated whatever population proves amenable to adopting it, we expect participation to stabilize since human population changes slowly compared with most economic effects. adoption incentive and long term supply stability. the dynamic interest rate mechanism creates a potentially strong adoption incentive in early stages, as our previous discussions in section showed that the interest rate r t = ( + n t )( − α) − . we illustrate this adoption incentive through an example. suppose that the number of participants doubles in one period (n t = ), for example. the interest rate r t would be close to , if α is sufficiently low, implying that the nominal savings of "early adopters" nearly double in just one period. this does not mean that real value necessarily doubles correspondingly, of course. but if the new adopters put the currency in active use and circulation similarly to the existing users, thereby growing the real popcoin economy roughly proportionally as well, then the early-adoption reward will also be meaningful in real value. when popcoin successful saturates among all the potential users, with our long-term assumption on population size, the interest rate would drop to nearly zero, i.e., the early-adoption reward tapers off and disappears. mathematically, a negative interest rates is equivalent to ǫ < α/( − α) when t ≥ τ . the long-term stability of popcoin supply is a significant distinction from the fiat currencies' supply, which grows exponentially over time. we utilize three different metrics to analyze how the monetary policy of popcoin can have effects on inequality among all participants . these metrics complement each other, in that some capture aspects overlooked by others. we emphasize that, it is one of the most significant distinct property from current fiat currencies that the design of popcoin itself reduces the inequality and brings a theoretical upper bound of inequality. reducing inequality through demurrage. when the number of participants is stable and fixed, after each devaluation of the existing popcoins and distribution of basic income to every participant, the inequality level reduces. we first measure inequality by both variance and the gini coefficient. for the variance, the inequality is strictly reduced, since in economics, the gini coefficient aims to measure the inequality level within a group of people. the gini coefficient g is defined as half of the relative mean absolute difference of variables, i.e. we know from eq. ( ) that, when the number of participants is fixed, the popcoin supply is fixed as well. therefore, after the devaluation and distribution of the new popcoin, the mean of the participants' balances remains unchanged. hence, we obtain therefore, when the population size is stable, the popcoin monetary policy reduces inequality measured in both variance and the gini coefficient. next, we analyze the inequality level between any two participants. we use the ratio of their popcoin balances to measure the inequality level: for any pair (i, j) , e i,j is the inequality ratio between them, and according to the definition, when e i,j = , the two participants have the same amount of popcoin balance, and a bigger e i,j means a higher inequality between the two participants. without loss of generality, we assume x i >= x j (otherwise we can switch i and j). for any pair (i, j), immediately after the demurrage and new basic income distribution, we have therefore, the inequality ration will not increase after the event, and if x i > x j , the inequality is strictly reduced. upper bound on inequality. we analyze the upper bound on inequality in terms of the variance across all participants' balances, the gini coefficient, and ratio between any two balances. to have a fixed sample size, we continue to assume the number of participants is stable and fixed. because we investigate the worst situation, x can be arbitrary with condition x i >= for any i and n i= x i = m = α bn . for any distribution of x satisfying the conditions, the upper bound of variance is (proof in appendix c. ) a gini coefficient of one indicates maximal inequality. for large and finite size of participants, where only one person has all the popcoins, and all others have none, the gini coefficient will be nearly one. when the number of participants tends to be infinite, the gini coefficient will be one. in our case, after the demurrage and distribution event, the gini coefficient will be very close to − α. specifically, we have for the inequality ratio between any two participants, after a devaluation and basic income distribution, we have (proof in appendix c. ) the optimization problem can be written as by applying properties of variance, we have therefore, the optimization problem is equivalent to bn ) and the equality is achieved when x i = α bn, i ∈ n and x j = , for all j ∈ n and j = i. substituting the results, we obtain the upper bound is ( −α α b) (n − ). we first prove the upper bound with fixed n . the optimization problem can be written as the denominator is constant with a fixed n and n i= x i = α bn . let us assume that the equality is achieved when x = α bn and x i = , ≤ i ≤ n . substituting the results, we obtain the upper bound is ( − α) n − n . when n tends to infinity for n ≥ , let us assume that the equality is achieved when x = α bn and x i = , ≤ i ≤ n . first, we focus on formulating the long-term exchange rate of popcoin to other fiat currencies. for this purpose, we assume that (a) popcoin has successfully saturated a sufficiently large community for general transactions, (b) price is flexible in the long run, and (c) that purchasing power parity (ppp) holds in the long run. we adopt the ppp theory [ ] to model popcoin's long-term exchange rate. the ppp theory argues that two currencies are in equilibrium when a basket of goods is priced the same in both currency area, taking into account the exchange rates. mathematically, the exchange rate can be formulated as a function of several important economic indicators, i.e., where m , p , y and l denote the currency quantity, the price level, the real income and the liquidity demand of the currency, respectively. the subscript p denotes popcoin and $ denotes the compared fiat currency. e p/$ is the exchange rate between the two currencies. here we further assume a fixed liquidity demand in the long run analysis and re-denote it byl. money supply for a fiat currency does not have a single "correct" measure. instead, it has several definitions for various purposes, for different countries or under their accounting rules. this section uses m as the supply of fiat currency, including cash, demand deposits, and saving deposits in banks. m is usually the key economic indicator forecasting inflation [ ] . by contrast, cryptocurrency generally has a clear definition of money supply. anyone can easily compute the total supply of bitcoin at any time, for example, based on the block number. in popcoin, anyone can trivially calculate the total popcoin supply based on eq. ( ). the ongoing development of decentralized finance (defi) will likely lead to other various definitions of money supply in the future. in any case, cryptocurrency and fiat money have fundamental differences: the cryptocurrency deposit in banks will never be like the cryptocurrency recorded in the decentralized blockchain since there is no central bank or government to bail out the banks. the trend of money supply for fiat currencies has always been increasing so far. the plot of the usd m money stock provided by federal reserve economic data (fred), for example, clearly shows this trend. on the other hand, cryptocurrency generally has a clear policy for its supply, maintained by machines enforcing software-encoded rules. it is therefore easy to forecast the future supply of cryptocurrency. this is an important feature as it reduces complexity in predicting the exchange rate of crytocurrencies relative to a fiat currency. the popcoin exchange rate relative to fiat currencies is formulated as below by transforming eq. ( ) into its relative form where µ is the growth rate of currency supply, and g is the real income growth rate. this equation formulates the change of the exchange rate d as the difference of currency growth and real income growth in both currency areas. if we assume that both currency areas have the same real income growth, the exchange rate is completely determined by the difference of currency growth. recall that eq. ( ) states that the only factor dominating the supply of pop-coin, other than time, is the number of participants or population size. thus, the growth rate of popcoin is the same as population growth rate. if we further assume that the change of population is limited and relatively slow, the supply of popcoin will be similarly constant and stable. with the assumption that growth rate is stable in the long run, eq. ( ) takes this reduced form: the end result is simple: as long as the population size is stable and the fiat currency supply expands as usual, the long-term level of the exchange rate of popcoin relative to inflationary fiat money will always increase over time. in this subsection, we briefly demonstrate a model for short-run analysis. we adopt an asset approach to explain the exchange rates in the short run [ ] . in this approach, we consider all currencies to be assets, and therefore currency holders could have capital gains on their currencies by participating in a lending market. for popcoin, its nominal interest rate depends on two factors: (a) the interest rate from the popcoin mechanism and (b) the interest rate from lending. at the end of this subsection, the short-run analysis gives us a guideline on how to reduce fluctuation of the short-run exchange rate. the short-run analysis relies on the long-run analysis and its assumptions. we further assume that (a) the exchange rate predicted by the long-run analysis is the expected future exchange rate, (b) the price level in the short run is sticky, (c) there is a sound lending market, and (d) the nominal interest rate is flexible and uncovered interest parity (uip) holds in the short run. the uip theory states that the exchange market is in equilibrium when the expected rates of return on each type of currency investment are equal. mathematically, this can be formulated as where i denotes the nominal interest rate of the currency, and the superscript e means the expected value in the future. based on our assumption, the expected exchange rate is from our long-run analysis or in contrast to the long-run analysis, in which we assume that the price level is flexible and prices adjust to bring the market to equilibrium, in the short run we assume price is sticky, and it is the adjustment of nominal interest rates in each currency zone that brings the money supply and money demand into equilibrium. hence, unlike in the long run, we assume that l is a decreasing function of the nominal interest rate of i. mathematically, for a currency, we have we now have all the building blocks to predict the exchange rate of popcoin in the short run. when popcoin has successfully saturated in a community with a stable population size, implying its supply is stable and predictable, with all else equal, a permanent issuance of the compared currency would influence the exchange rate in both the long run and short run. in the long run, we know that an increase of m e c caused by the increase of the currency c leads to the expected exchange rate e e p/$ decreasing. in the short run, as the price level is fixed, according to the eq. ( ), its nominal interest rate will decrease. both effects would lower the spot exchange rate according to the eq. ( ). denoting the new spot exchange rate as e ′ p/$ , it is not hard to prove that e ′ p/$ < e e p/$ , a phenomenon that economists refer to as exchange rate overshooting. the analysis tells us that when there is a tendency for more permanent monetary policy shocks, then there will be a tendency for a more volatile exchange rate [ ] . this suggests that having a fixed monetary policy as in popcoin could potentially help to reduce volatility of the exchange rate. we analyze popcoin's purchasing power by formulating its inflation rate. inflation reduces a currency's purchasing power as the prices of goods and services increase. this is a long-run analysis based on the assumption made in appendix d. , and is not necessarily applicable in the short run. we begin our analysis with the quantity theory inflation equation [ ] , i.e., where π is the inflation rate, µ is the growth rate of the currency supply, and g is the real income growth rate in its currency zone. as we stated earlier, popcoin's nominal growth rate is equal to the growth rate of the population in its currency area. therefore, we may apply the equation to popcoin as where n is the population growth rate, n t = n t /n t− − . this equation simply tells us that, if the population is relatively stable in the long run (n t is or very close to ) and the real growth rate is positive, popcoin will deflate rather than inflate. with little or no real income growth, the price level denominated in popcoin will be stable. thus, in contrast with the mainstream tradition of central banks targeting a mild inflation rate [ , ] , popcoin is deflationary in the long run whenever the economy's real growth rate exceeds population growth rate. is this a bug or a feature? in classical economics it would definitely be a bug, due to the risk of deflationary spirals. but would the same risk apply to a popcoin economy? the risk of deflationary spirals. we argue that a classic deflationary spiral is unlikely to occur in popcoin, and hence that deflation is not necessarily bad for popcoin, because of the way it creates money via basic income rather than debt. this conclusion may be true as well for other cryptocurrencies whose issuance does not rely on debt, such as bitcoin's early period before mining became powerand capital-intensive [ ]. to understand why, we have to examine how today's fiat money is "printed". as we stated earlier in this section, there are many different measures of the currency supply. why there are so many? one of the reasons is that not only central banks can "print" money, but also commercial banks can "print" money [ , ] . more specifically, monetary base (mb) is created or directly controlled by the central bank, while m includes the money created by commercial banks. how is money created and distributed? in cryptocurrency, this creation is simply written in its code. for instance, bitcoin is created whenever a new block is mined, and the newly issued bitcoins are distributed to the miner of the block, while popcoins are created regularly and distributed to every participant equally. in the fiat money system, no one solves mathematical puzzles, nor does everyone receive an equal portion of newly created currency. how does it work in fiat currency? a simple and infeasible solution is to give the newly created money to the government directly. however, this power is so easy to be abused and nowadays the majority of countries have more or less independent central banks making sure that newly created currency will not directly put into the government's account. the real "secret" is that today's fiat money is based on credit. money is created whenever an entity borrows money from commercial banks or central banks. this entity could be a government that wants to fund its deficit, an individual who takes a mortgage, or even a bank (including the central bank) itself which creates money from the thin air by borrowing money to itself to fund its purchase. meanwhile, when the borrower repays, the principal of loans is destroyed [ ] . this implies that the key distinction from cryptocurrency is that cryptocurrency lending does not create new money in general. how does the mechanism of fiat money creation relate to deflation? here we adopt an analysis by fisher in [ ] to illustrate the deflationary spiral and to argue why popcoin and cryptocurrency do not suffer from it. we begin the spiral by a fall of the price level or deflation. this causes the rise of the real interest rate, increasing the cost of borrowing. this urges borrowers to reduce their demand for loans, causing the money supply to fall. all else being equal, reduced currency supply means price level will decrease even further, and therefore a deflationary spiral has formed. in contrast to fiat money, however, popcoin is not based on credit. a fall in the price level does not influence the popcoin supply, because new money is injected constantly via debt-free basic income rather than through loans. although deflationary spirals are a major risk for fiat currencies, therefore, we have substantial reason to believe that popcoin and other non-debt-based currencies could substantially mitigate this risk. as with other cryptocurrencies, speculative investment is likely to happen in popcoin. this may cause unpredictable exchange rate swings in the short run, as in today's market for unpegged cryptocurrencies. is this a bug or a feature? we reiterate that in popcoin, price stability is not the primary goal but only a secondary goal subsidiary to long-term fairness and equity, as discussed in section . . thus, while stability would be nice to have if and when we can get it, we are willing to live with some instability -especially short-term instability -if doing so helps us reach the currency's long-term monetary policy objectives. to analyze susceptibility to speculation, it is useful to distinguish between three situations that might prevail with respect to the participating user population: rapid growth, stability, or rapid degrowth. early-adoption rewards dominant during rapid growth. first consider the situation in which participation in popcoin is growing rapidly, as might occur in an early phase if it achieves a critical mass of interest to drive rapid adoption as happened to bitcoin in its early years. in such a phase, speculative investment is encouraged by popcoin's "early-adopter's" reward mechanism as described in in appendix b. with belief that more participants will adopt pop-coin scheme in the future, current participants can expect a positive reward and gain more popcoin from hodling than spending it. with this adoption incentive, people may be more willing to adopt popcoin, and to convince others to adopt it as well, which may be exactly what is desired in such an early phase. because the early-adopter's reward tapers off to nothing as participation growth slows or eventually stops, however, this reward mechanism -and the speculative swings and bubbles it might contribute to -should be temporary and self-limiting. hodling tax during periods of population stability. once an early rapid-growth phase stabilizes and popcoin has saturated whatever community is amenable to adopting it, we expect popcoin's demurrage to take over eventually and disincentivize too much speculation by effectively "taxing" it. we utilize the model and assumptions in appendix d. to illustrate the influence of speculative investment in the short run on its exchange rate to other currencies. we model the hodling consequence as a temporary shock of reducing the popcoin supply, assuming all other exogenous variables remain unchanged and fixed. as eq. ( ) showed, the nominal interest rate would increase caused by the temporary shock to popcoin. as the expected future popcoin supply remains fixed, eq. ( ) shows that the spot exchange rate of e p/$ decreases, leading to the appreciation of popcoin. while the appreciation of popcoin benefits the popcoin community members who purchase goods and services denominated in other currencies, speculators need to pay the taxi.e., the demurrage fee -under the assumption that the population size of the popcoin community is reasonably stable. therefore, speculating on popcoin is discouraged after a rapid-growth phase stabilizes. however, if we consider the utility of a rational participant, we obtain a different result: a rational participant might be willing to pay a demurrage fee for keeping his popcoin to maximize his utility as a whole. rational saving and proportional tax. a rational participant with prefect foresight may save his popcoin for the future, even though popcoins are subject to lose their value by demurrage mechanism. we prove that the popcoin mechanism can automatically distinguish rich and poor and apply different proportional tax rates of their saving, even though everyone is subject to the same global interest rate. a rational participant may save some of his income by reducing the consumption today to increase the consumption in the future, even when the saving is subject to lose some of its value by demurrage. let us consider a simple world, where agents with prefect foresight who can only live for two periods, of which he is young in the first period and old in the second period. the agents are able to have earned income apart from basic income b when young, and only basic income when old. we use in i t to denote the earned income of the agent i at period and out i t to represent his expenditure at period of t. therefore, at the end of period , his balance is his balance in period is subject to change by a factor of r (the global interest rate at period ) due to the mechanisms of demurrage and early adoption reward. hence, at the end of period , his balance is because the agent knows that he can only live for two periods, it is rational for him to spend all his popcoin before the end of period two. therefore, we have by combining eq. ( ), eq. ( ) and eq. ( ), we can derive his budget constraint as the problem he is facing is to maximize utility of consumption in real term. suppose that the utility is give by ( out i p ) / + ( out i p ) / , we can find the utility as the following function of out i : we can find the maximum value by differentiating this function with respect to out i , and set the derivative equal to zero. the utility function achieves maximum value when in order to better understand this formula, let us consider some special cases. for simplicity, we assume that p = p . for an agent with zero earned income, his consumption is equal to b/( + r ) in the first period. when r = , his consumption is equal to his basic income i.e.he will consume all of his income in the first period. if r > , he can improve his utility by consuming less than his basic income in the first period, so that he can receive the extra reward in the second period. if r < , the best option for him is to consume more than his income. however, if borrowing is not possible for him, the best decision is to consume all his basic income. now, let us consider the opposite situation. this time, we assume a agent belonging to the high-income group, in which they are able to have super high earned income in the first period i.e. in i ≫ b. from eq. ( ), his first period consumption is approximate equal to in i /( + r ). when r = , he is about to save half of his income, and when r > , he is going to save even more to enjoy the reward. if r < , although his saving is decreased, it is still rational for him to save a significant amount of popcoin, so that he can improve his consumption in the second period, even if the savings are subject to lose some of their value. therefore, if we consider utility, a participant may rationally save some of his income so that he can increase his utility as a whole. hence, the rich pay higher tax rates than the poor, even they are subject to the same global demurrage rate. popcoin therefore automatically distinguishes the rich and poor and charges different tax rates according to their income level. the risk of rapid degrowth. we may worry that there is a risk that if participation in popcoin ever starts decreasing, this could lead to a different form of positive feedback loop or "death spiral" due to the effect opposite that of the early adopter's reward above. that is, if participation is decreasing, a basic income acquired at time t − will tend to be worth less if it is saved until time t. would this trigger more participants to leave the system, increasing the rate of participation degrowth, and so on? while this is an issue worth considering, it seems unlikely to be a major problem for one simple reason: basic income is free to all participants. so even if participation drops for whatever reason and the remaining participants suffer an "early adopter's penalty", all those remaining participants, if rational, still gain more by continuing to participate than by dropping out and giving up their basic income. for this reason, the main risk we perceive to popcoin collapsing is not through a participation death spiral but through other reasons, such as because interest and economic activity using popcoin becomes too weak and people stop using it simply because it is not useful or valuable enough to be worth the effort to participate. popcoin's definition and monetary policy as defined by algorithm has the technical drawback that all wallet balances on the ledger -not just the one wallet per participant that receives new basic income -must be adjusted for participation changes and demurrage in each period. for implementation convenience and efficiency, we may prefer an alternative method of enforcing popcoin's monetary policy without affecting the nominal values of all wallet balances at each minting. we can achieve this goal by introducing a closely-related currency we will call poplet, which has a time-varying exchange rate with popcoin. the exchange rate is maintained by software, so popcoin's users do not need to be aware of the existence of poplets. in bitcoin, the satoshi represents the smallest atomic unit of bitcoin that can be transferred. similar to the satoshi, the poplet is the indivisible atomic unit in popcoin. unlike bitcoin, whose"exchange rate" between satoshi and bitcoin is constant, we adopt a time-varying exchange rate between poplet and popcoin, so that we do not need to update wallet balances at mintings. the rebasing mechanism is achieved by changing the exchange rate between poplet and popcoin, as demonstrated in algorithm . in short, poplet is an inflationary but participation-independent currency, which can always be converted to or from popcoin by adjusting for current participation and inflation incurred thus far. purchasing power parity in the long run anonymous: democratic value and money for decentralized digital society gooddollar: a distributed basic income irving fisher's debt deflation analysis: from the purchasing power of money ( ) to the debt-deflation theory of the great depression ( ). the european journal of the history of the case for a long-run inflation target of four percent bitcoin: economics, technology, and governance proofof-personhood: redemocratizing permissionless cryptocurrencies voucher privatization encointer-an ecological, egalitarian and private cryptocurrency and self-sovereign identity system weaponized health communication: twitter bots and russian trolls amplify the vaccine debate reward sharing schemes for stake pools the authors wish to thank rainer böhme, xi chen, yawen jeng, luisa lambertini, alexander lipton, and alexis marchal for their extremely helpful comments and suggestions. this research was supported in part by u.s. office of naval research grant n - - - and by the axa research fund. key: cord- - y x authors: platt, daniel e; parida, laxmi e; zalloua, pierre title: lies, gosh darn lies, and not enough good statistics: why epidemic model parameter estimation fails date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: y x an opportunity exists in exploring epidemic modeling as a novel way to determine physiological and demic parameters for genetic association studies on a population/environmental (quasi) epidemiological study level. first, the spread of sars-cov- has produced population specific lineages; second, epidemic spread model parameters are tied directly to these physiological and demic rates (e. g. incubation time, recovery time, transmission rate); and third, these parameters may serve as novel phenotypes to associate with region-specific genetic mutations as well as demic characteristics (e. g. age structure, cultural observance of personal space, crowdedness). therefore, we sought to understand whether the parameters of epidemic models could be determined from the trajectory of infections, recovery, and hospitalizations prior to peak, and also to evaluate the quality and comparability of data between jurisdictions reporting their statistics necessary for the analysis of model parameters across populations. we found that, analytically, the pre-peak growth of an epidemic is limited by a subset of the model variates, and that the rate limiting variables are dominated by the expanding eigenmode of their equations. the variates quickly converge to the ratio of eigenvector components of the positive growth rate, which determines the doubling time. there are parameters and independent components in the eigenmode, leaving undetermined parameters. those parameters can be strikingly population dependent, and can have significant impact on estimates of hospital loads downstream. without a sound framework, measurements of infection rates and other parameters are highly corrupted by uneven testing rates to uneven counting and reporting of relevant values. from the standpoint of phenotype parameters, this means that structured experiments must be performed to estimate these parameters in order to perform genetic association studies, or to construct viable models that accurately predict critical quantities such as hospitalization loads. infection , , transcription and replication , by sars-cov- involves a number of rate limiting interactions with host cells that are likely to be modulated by mutations in cellular as well as viral genes. at the same time, phylogenetic analysis shows geographic specificity , , indicating that geographic regions may show specific exposure to distinctive snp combinations, or viral haplotypes, in sars-cov- . this specificity suggests a benefit to exploring relationships between duration of the prodromic phase, proportions of asymptomatic cases , proportions of severe cases, rates of recovery, among other infection attributes , that define temporal progression of compartmental epidemic models, starting with sir (susceptible-infected-recovered) models . beside host and viral genetic impacts, other aspects driving sars-cov- rates are population specific and demic, such as the impact of age on both asymptomatic and mild cases, as well as the proportion of severe and critical cases. other aspects include normal social distance, and how effectively social-distancing rules have been followed. hospital survival may also reflect impacts of some genetic susceptibility, presence of comorbidities (hypertension, diabetes, asthma, lung disease, obesity and others yet to be identified) as well as the level of stress on the region's medical facilities and medical staff. in this paper, we seek to identify the limitations of using compartmental models to estimate or test hypotheses concerning parameters governing the growth of sars-cov- epidemics. we also seek to investigate what type of epidemic variable tracking is necessary to effectively quantify the parameters that are suitable for hypothesis testing at the level of environmental exposure in epidemiological studies. compartmental models count individuals at different stages of progression of a disease, where each stage of progression is marked by an event that has a well-defined rate. for example, from time of infection to the time the person can transmit disease has a time distribution, that, for enough people in the compartment, will tend to center on an average by the central limit theorem for large enough samples drawn from any given distribution. there is evidence that covid- presents symptomatic cases and asymptomatic cases, with asymptomatic cases [ ] [ ] [ ] less likely to be identified and isolated [ ] [ ] [ ] [ ] [ ] . there is an incubation period after infection that lasts until the incubating individuals become infectious. there has been some early estimates based on confirmed cases , with more evidence of pre-symptomatic transmission being noted , yielding faster incubation. incubation partly accounts for the observed lag when social distancing or other viral spread prevention policies are imposed. for the most part, infections appear to be transmittable prior to overt symptoms, allowing for a pre-symptomatic period that may convert to symptomatic. at the same time, some of those asymptomatic people remain asymptomatic until they are non-contagious . patients may still be infectious for several days after symptomatic recovery. symptomatic patients likely to be hospitalized are hospitalized more quickly than non-hospitalized patients recover. hospitalized patients in icu or required immediate ventilation tend to experience a longer time to recovery than nonhospitalized patients. those that stay on the ventilator for long periods tend to have a high mortality rate, and may stay on the ventilator for many weeks prior to dying. a compartmental model that captures the conditions status and durations count susceptible population members , incubating , infectious asymptomatic , infectious symptomatic , infectious people who will be hospitalized , those hospitalized who recover , and hospitalized leading to mortality . recoveries are , and mortalities are . the time from exposed to infectious is , where is partitioned into contributions to asymptomatic infectious , symptomatic infectious , and infectious that will be hospitalized , so that = + + . total removal time among asymptotic infectious is , with a fraction going to infectious symptomatic. infectious symptomatic removal time is . the period prior to hospitalization is ( + ) . the rate that the proportion that recovers is , and that which dies is . the model equations, reflecting an underlying markov chain, expressing these connections and rates are: table . the rate of infection for a susceptible individual depends on the probability that an infectious viral load is transferred, multiplied by the rate of encounters a susceptible individual has. the encounters can involve: other susceptible individuals, or symptomatic infectious people, which as a group tends to be isolated with a corresponding depressed rate of encounters , and undetected asymptomatic infectious people whose interaction rate is substantially higher, subject to social distancing regulations. the fraction of infectious symptomatic individuals that a given susceptible individual may encounter is , and the total number of susceptible individuals exposed to infectious symptomatic cases is . likewise, that for asymptomatic cases, the rate of symptomatic infections is . these terms drive the creation of new infections in the population. the force of the symptomatic group is the coefficient of , or . the number of the susceptible group that an individual can infect over their entire period of infectiousness is the reproduction number = , and similarly for the asymptomatic infectious group. these numbers primarily drive the rate of growth of the infection in the population, which early in the expansion is measured by the doubling time. early in the evolution of the infection, which may be defined as when − ≪ , the variables immediately involved in the feedback loop determine the rate limiting step. therefore, identifying the eigenvectors represent the linear combinations of , , , and that grow or decay with the that eigenvalue. the combinations of eigenmodes is determined by initial conditions. the leading eigenvalue will dominate with exponential growth yielding fixed proportions of each of the , , , and to each other. the other terms turn out to identify rates related to the delay time for the system to respond to changes in distancing policy due to incubation time, to imbalances between symptomatic and asymptomatic patients, and to the decay of . data from new york state were obtained from the covid tracking project . table . published times for compartmental conversions, proportions, and derived rates. . cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . value notes . ( . - . ) days , . ( . - . ) testing in new york state, starting on / / , labeled as day . on / , day , ny state received permission to contract for its own sars-cov- testing. statewide "distancing" started on / , day , with the signing of the "new york state on pause" bill. prior to that, local jurisdictions had already been imposing local ordinances against assembly, and started closing schools. figure shows the cumulative total testing and positive test numbers indexed by day. testing has been driven by tracking contacts of discovered cases which is reflected heavily in the close alignment of total tests and positive tests. on / , the total number of tests increased from to , with surges to the , level, then , , then , showing rapid subsequent . cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . growth. early in the testing, from day to , the rate of growth of positive cases was = . ± . , corresponding to a doubling time of . ± . . from day to day , the rate of growth of positive cases was = . ± . , corresponding to a doubling time of . ± . . these numbers suggested very high rates of contagious transmission. these doubling times were reported by governor cuomo in some of his earliest briefings. if, as tracking numbers increased, testing surveillance was broad enough to pick up community spread individuals proportional to total numbers of tests applied, then the proportion of positives from the tests may reflect population rates. however, if rates are tightly limited to immediate known cases, then the reported positives will be a better estimate of underlying population, since the fraction of those seeking medical assistance should be proportional to the exposed number in the population. when available tests increased, the apparent rate grew substantially. therefore, infected population growth may be more closely reflected in the fraction of positive results normalized by total number of tests applied, in spite of very highly biased sampling selection. for a given proportion of ill patients who seek help, this should track . cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint with the fraction of the population who is ill. however, this may be subject to growing awareness of the population to get help with covid- infections. first, consider the idea that tests may be broad enough to sample spread. when test numbers were low, the likelihood that targeted testing would reflect the general population was also low and sampling uncertainties large. therefore, a lower bound on testing levels was applied. this cut samples prior to / . later, test ratios started to demonstrate a downwards bend. this shoulder was cut for samples beyond / . new york doubling time was estimated from a regression between the log of positive test ratios versus time, yielding = . ± . with a doubling time of . ± . adjusting for testing counts. in the alternative scenario, positive samples reflect the proportion of symptomatic patients seeking medical aid, a possibility since the testing was so closely tied to diagnosed patients plus contact surveillance. a regression was performed on the cumulative positive counts shown in figure c ) yielding = . ± . per day, with a doubling time of . ± . days. . cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint last eigenvalue is = − . , associated with the decay of from equilibrium values with eigenvector = ( ). figure shows a log-linear plot of the rate-limiting variables for a numerical integration of the entire system of differential equations. the pre-peak segment shows a clear view of how the system is dominated by the leading exponential eigenmode of the growth, including the proportions between variables represented in the eigenvector of the leading eigenvalue, which determines the slope. . cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . figure shows the evolution of the system variables in a linear-linear plot. the lags in the peak variables shown in figure a identify the peak pulse through the system of linear equations. the "est" entries in table for represent values commensurate with (but not a fit to) the ny hospitalization levels . they are a factor of smaller than those fitting the wuhan hospitalization rate . as such, it is clear that the impact of covid on features such as progression to hospitalization, response to treatment for symptomatic patients, whether patients are identified in time to stop progression to serious or critical stages may impact survivability. the model predicts fatalities per million, peak recovering hospitalizations of on day , and peak mortality hospitalization (primarily long-term ventilator load) of on day . figure b includes susceptible and recovered variables. the range of variation of these variables appears to dwarf the fraction of the population that is incubating, infected, or involved with hospital load. one feature of the equations is that the rate of flow of individuals through a compartment may not be reflected in the total number in the compartments at any given time, even at their peaks. at the end, these rates would leave , per million uninfected and susceptible, with , recovered per million. table . exponential growth rates, corresponding doubling times for various populations and measurements given available data. the difficulty in understanding how the testing protocol impacts estimations of rates is illustrated in the new york state rates shown in table . considering cases as a representative sample of a fixed proportion of the infected population argues for computing a rate based on cumulative cases. if, on the other hand, the testing generated a random sample of the broader population, more testing would identify more individuals simply because there were more tests. if so, the proportion of positives to total tests may be a closer approximation to the population, and the total positives would be proportional to the square of the actual proportion of diseases, resulting in a doubling of . that seems to be roughly what was observed between the two new york state regressions. on the other hand, cumulative rates for two other . cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . jurisdictions, lebanon and new south wales, australia, show rates similar to each of the two new york state numbers. and while the new york state proportional model gives an expected factor of in the rate, it is the cumulative rate that more closely resembles the growth and peak in new york, not the relative proportion rate. more, the shifts in test availability and distancing initiation are all visible in the new york data, which contributes to the difficulty even of identifying exponential growth regimes, much less identifying an exponential rate that constrains the available model parameter space. one of the major goals of epidemic modeling is to predict mortality and resource load on community medical facilities: how many beds, how many ventilators, how much pharmaceuticals, among other resources will be needed to get through the epidemic. early epidemic growth for this system is dominated by the largest eigenvalue of coefficients governing the rate-limiting variables. this eigenvalue determines the doubling time of the growth, and imposes one constraint on those coefficients; the eigenvectors impose three more constraints on the system, leaving five coefficients undetermined. essentially, all of the ratelimiting relevant epidemic variables grow at the same rate maintaining fixed ratios. however, as they near peak, the variable trajectories become more differentiated, with lagging or leading peaks emerging as the impact of filters through the system of equations. however, at peak, it is already too late to allow time to acquire and deploy needed resources to hospitals and clinics. by itself, the trajectory of these models in pre-peak growth offer little hint as to final needs. further, there are a number of combinations of parameters that would yield the same leading eigenvector and eigenvalue. more so, the parameters that govern these epidemic models tend to reflect physiological rates of how the disease expresses itself in individuals, as well as effects that are moderated by demic characteristics. examples are age structure in the population, which impacts both asymptomatic cases , and severity of disease . identification of asymptomatic cases has been problematic since testing protocols tended to require symptoms, or contacts with known infected people. one case in california went untested for days because she had no known contacts. cases that advance to severe or critical depend on other factors, such as treatment modalities prior to development of advanced symptoms. the rate of transmission depends on physiological parameters as well as normal social distance and social distancing response to an epidemic, how public institutions such as schools are run, how grocery shopping interactions are handled, whether known infections are isolated and other factors specific to each community. given how widely these parameters may vary from population to population, how they vary: how they depend on the geographically specific dominating sars-cov- lineages dominant within a given geography , , and how they depend on behavioral, social, age structure, and other factors of a population, it is worth seeking whether and how these factors relate to the expressed epidemic model rate parameters as phenotypes. . cc-by-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . since the problem of identifying rate limiting parameters prior to peak is underdetermined, these rates must be determined elsewhere. most statistical reporting does not provide nearly enough information to extract these factors, even at an environmental (quasi-) epidemiological experimental design standards. further, jurisdictions are applying tests to try to identify new cases that are related to other identified cases through contact. the "enrollment protocol" was not designed to understand the spread in the population, but rather to try to identify patients and remove them from circulation by isolating them. more and broader testing is applied as test kits become more available. test kits may not be uniform with loss of sensitivity depending on the stage of the infection and/or the type of swab taken (nasal, nasopharyngeal or sputum). from jurisdiction to jurisdiction, testing and reporting protocols vary, making it difficult to compare jurisdictions, or even the same jurisdiction to itself from day to day. the rate of growth and doubling time may reflect availability and levels of testing more than the actual disease in the population. perhaps the best way to acquire the necessary parameters would be a prospective longitudinal study cohorts in multiple jurisdictions. enrollment should be randomized, reflect regional characteristics such as sex and age, and the criteria should be shared across populations participating in the study. during the course of the study, subjects will be monitored for changes in status a) from susceptible to incubating recording dates of exposure (if possible), b) to infectious (symptomatic or asymptomatic, with a clearly defined standard for determining possible "infectious" condition) conversion and dates, c ) for asymptomatic to symptomatic conversions and dates or c ) recovery dates, d) symptomatic to recovery conversion dates, or e ) hospitalization dates, e ) recovery from hospitalization dates, e ) icu admission dates, e ) icu recovery date, e ) ventilator treatment start date, e ) ventilator recovery date, e ) date of death. a record of how each subject moves through the model compartments, together with time distributions, can provide phenotypic parameters that modelling alone cannot, offering insight into the biology, response of the disease to medications, comorbid conditions, demic characterizations, and other features relevant to the impact of covid- . further, these parameters provide a uniform basis for comparisons between populations necessary for complete model constructions that yield distributions of trajectories and confidence intervals for timing and peak loads, and which can provide a full epidemiological exploration of how individual subject phenotypes respond to environmental, genetic, comorbid, and behavioral factors that may yield valuable information for biological, clinical and pharmaceutical development. as such, these models may be used to test and verify measurements of physiological parameters, and to identify evidence whether some factor strong enough to generate deviations is missing. a response to an article in nature stated: "a well-known lawyer, now a judge, once grouped witnesses into three classes: simple liars, damned liars, and experts. he did not mean that the expert uttered things which he knew to be untrue, but that by the emphasis which he laid on certain statements, and by what has been defined as a highly cultivated faculty of evasion, the effect was actually worse than if he had." the statement was applied to the specific issue of expert forensic testimony. the statement has been restated as "lies, damn lies, and statistics." the message serves as a warning that statistics collected for certain purposes may not be suited to other purposes. that unsuitability does not reflect any attempt at obfuscation. specifically, in this case, the use of testing, positive test counts, etc are tilted towards identifying patients who are likely to have specific treatment needs, and to try to identify contacts to stop epidemic spread. these uses render the reported statistics problematic for modeling. physiological parameters based on identified patients may be biased in terms of the patients who were identified, and the methods by which they were identified. further, protocols shifted as previously unrecognized community spread and asymptomatic individuals were recognized to be significant contributors to viral spread. finally, modeling not only can provide important information planners need for capacity loads, but models can also test whether the parameters as understood describe how the disease behaves in a population. a failure to predict may indicate an important factor in the disease's behavior that had not been recognized. in order for this to work, a more formally structured prospective cohort study, with adequate annotations of pharmaceuticals, comorbidities, and other factors, is likely the best way to ensure all the rates are measured on a consistent footing throughout the course of the epidemic. the proximal origin of sars-cov- structural basis of receptor recognition by sars-cov- dynamics of coronavirus replication-transcription complexes an overview of their replication and pathogenesis variant analysis of covid- genomes phylogenetic network analysis of sars-cov- genomes temporal dynamics in viral shedding and transmissibility of covid- report of the who-china joint mission on coronavirus disease a contribution to the mathematical theory of epidemics presumed asymptomatic carrier transmission of covid- | global health clinical characteristics of asymptomatic infections with covid- screened among close contacts in nanjing estimating the asymptomatic proportion of coronavirus disease (covid- ) cases on board the diamond princess cruise ship investigating the impact of asymptomatic carriers on covid- transmission | medrxiv evolving epidemiology and impact of non-pharmaceutical interventions on the outbreak of coronavirus disease substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (sars-cov ) modelling the impact of covid- in australia to inform transmission reducing measures and health system preparedness predicting the impact of asymptomatic transmission, non-pharmaceutical intervention and testing on the spread of covid estimating the generation interval for covid- based on symptom onset data transmission interval estimates suggest pre-symptomatic spread of covid- the incubation period of coronavirus disease (covid- ) from publicly reported confirmed cases: estimation and application estimation of the asymptomatic ratio of novel coronavirus infections (covid- ) republic of lebanon ministry of public health epidemic data for novel coronavirus covid- will children reveal their secret? the coronavirus dilemma the whole duty of a chemist key: cord- - v qufw authors: vierlboeck, maximilian; nilchiani, roshanak r; edwards, christine m title: the easter and passover blip in new york city date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: v qufw abstract and executive summary - when it comes to pandemics such as the currently present covid- [ ], various issues and problems arise for infrastructures and institutions. due to possible extreme effects, such as hospitals potentially running out of beds or medical equipment, it is essential to lower the infection rate to create enough space to attend to the affected people and allow enough time for a vaccine to be developed. unfortunately, this requires that measures put into place are upheld long enough to reduce the infection rate sufficiently. in this paper, we describe research simulating the influences of the contact rate on the spread of the pandemic using new york city as an example (section iv) and especially already observed effects of contact rate increases during holidays [ - ] (section v). in multiple simulations scenarios for passover and easter holidays, we evaluated %, %, %, and % temporary increases in contact rates using a scenario close to the currently reported numbers as reference and contact rates based on bioterrorism research as a 'normal' baseline for nyc. the first general finding from the simulations is that singular events of increased visits/contacts amplify each other disproportionately if they are happening in close proximity (time intervals) together. the second general observation was that contact rate spikes leave a permanently increased and devastating infection rate behind, even after the contact rate returns to the reduced one. in case of a temporary sustained increase of contact rate for just three days in a row, the aftermath results in an increase of infection rate up to %, which causes double the fatalities in the long run. in numbers, given that increases of % and % seem to be most likely given the data seen in germany for the easter weekend for example [ , ], our simulations show the following increases (compared to the realistic reference run): for a temporary % surge in contact rate, the total cases grew by , , the maximum of required hospitalizations over time increased to , , and the total fatalities climbed by , accumulated over days. as for the % surge, we saw the total number of cases rise by , , the maximum number of required hospitalizations increase to , , and the total number of fatalities climb by , over days in nyc. all in all, we conclude that even very short, temporary increases in contact rates can have disproportionate effects and result in unrecoverable phenomena that can hardly be reversed or managed later. the numbers show possible phenomena before they might develop effects in reality. this is important because phenomena such as the described blip can impact the hospitals in reality. therefore, we warn that a wave of infections due to increased contact rates during passover/easter might come as a result! "a pandemic is the worldwide spread of a new disease" [ ] the above mentioned definition by the who describes the current global situation in regard to the virus named covid- , that emerged world wide in the past months. as of the writing of this paper (april ), there are , , confirmed covid- cases world wide and , confirmed deaths in over countries [ ] . the virus is confirmed to be transmissible from human to human [ , ] and has constantly been spreading due to contact between individuals. the problem with the spread is though, that while it seems like a simple mathematical model, it is dynamic complex system which does not necessarily behave in a linear way. thus, predictions can be difficult and the actual behavior of the whole system, and therefore the outcome such as fatalities and infrastructure strain, is hard to evaluate. one way to conduct such evaluations is to design a representative model which simulates and mimics the real world phenomena as close as possible. with such a model, certain parameters and influences can be assessed by modifying the model and observing its reaction, which is what this paper is about. due to the importance of the above described transmission from human to human and the involved contact, the research presented in the following paragraphs took a look at the effective contact rates between humans in a theoretical dynamic simulation using new york city as an example, in order to determine what factors play what role and how certain influences interact. therefore, various simulations and scenarios were assessed in order to discovered different behaviors and potential emergent phenomena based on and dependent on different factors. the second section will describe the research methodology, the model utilized for the simulations, and how the specific simulations were conducted. section iii describes the assumptions that were made in order to design and set up the model as well as the involved parameter as a result. section iv and v then demonstrate and discuss scenarios possible and likely in order to show the behavior of the system and certain emergent phenomena. lastly, section vi will summarize and discuss the outcomes and also give an outlook how research might continue. when looking at models for the spread of diseases, sir models present a simple and easy to adapt starting point for such situations. sir stands for "susceptible-infectiveremoved" and was first proposed by kermack and mckendrick in [ ] . the model is described as a differential system in which multiple factors depend on each other to determine the behavior of the three levels s, i, and r. the equations herein were as follows [also see ]: with these equations, a simulation system was be derived that models the current situation of the covid- spread in a simplified way. since the aforementioned infrastructure and hospital strain was of importance for the coronavirus pandemic, the model was modified to include time delays due to incubation and a portion of the infected people who would not go directly from "infected" to "removed" and rather move to hospitalization. from hospitalization then there were two options, either a delayed demise of the individual, or a delayed recovery, which adds the individual back to r. these additions modify the equations above as follows and add equations (iv) and (viii): the simulation model based on these parameters was setup in vensim [ ] with time and calculation steps of one day. a flowchart of the model is depicted in figure on the right. based on the equations and the structure shown in figure , the model was designed in order to allow for a flexible adjustment of the parameters, which will be described in section . with the model then, the chosen research methodology was applied as described by maria [ ] . herein, after the above described problem definition in a first step, the parameters of the model were set to yield an adequate and verifiable outcome. such a verification was conducted by comparing the model results to real world data that was reported during the current pandemic. wirth the set parameters (also see next section), multiple scenarios were simulated and examined based on various conditions that were chosen, always derived from real and current circumstances. these scenarios will be described in the fourth and fifth section. the outcomes were compared as far as the different levels of the simulations components go. for example, the infection rates and total cases could be compared to determine the speed of the spread and therefore the rise of the total case number over time. another option is the comparison and evaluation of fatality numbers and hospital strain over time to assess how different scenarios effect the end results and possibly discover potential shortages at certain times. these scenarios then allowed for a general evaluation and also the discovery of the main focus of this paper, the phenomenon we called the "easter blip" (section v). based on the results, predictions of possible behaviors of the current pandemic were deduced to potentially support governing and regulating decision in order to avoid and mitigated unwanted situations such as high fatality numbers or collapse of medical support for example. the next section will describe the assumptions the model was based upon to allow for simulations that mimic the current real world behavior as far as feasible. in order to design a model that could mimic and simulate the real world pandemic, the factors, described in the equations (iv) through (viii) above, had to be set so that the simulation results would be in accordance with real world situations and data. therefore, this section will outline the assumptions that were made to achieve the accordance. hence, the following sub-sections will describe one parameter each based on new york city (nyc) in , with a population of , , people [ ] . the infection rate of the model, which describes at what rate the susceptible population will be infected, was defined depending on two factors: infectivity (i) and effective contact rate (c). these two factors together with the infectious population (i) and the susceptible population (s) allow the calculation of the infection rate according to the following formula: the infectivity (i) was defined as a constant based on the likelihood of infection when people interact and hence was derived from various sources and set to % [ , ] due to the higher population density of nyc compared to the locations of the source data. the constant infectivity allowed a modulation and adjustment of the infection rate based on the second component, the effective contact rate. this rate was furthermore used to model and simulate real word behavior as circumstances like social distancing for example impact the effective contact rate of the population and therefore were ideal to be modeled this way. for the general magnitude of the effective contact rate, the amount of average contacts of people per day in nyc was researched in order to enable a realistic starting point without any measures such as social distancing. based on literature sources, the researched contact rate in nyc ranged from for people who do not use the subway up to at least for people who do utilize the subway [ ] . since this data was obtained and measured in and the population of nyc increased by % since then, this would yield contact rates of . and . today. given that the number of subway users in nyc is higher than in any other city in the united states [ ] , it was assumed that % of the nyc population take the subway on a daily basis and therefore are more active and effectively have more contact, also through surfaces. together with the number of contacts for non-subway users, this would yield an average effective contact rate without restrictions or social distancing of . . all in all, the infection rate therefore was defined by the following equation: with the parameters for the hospitalization and recovery rate were assumed to be directly connected as an infected person would either recover or be hospitalized (see figure ). therefore, the recovery rate was exactly the opposite portion of the hospitalization rate, yielding since the numbers of hospitalizations strongly vary by age group and therefore depend on demographics, an average hospitalization rate was calculated based on official data by the city of new york [ ] to allow for the use of a constant. the resulting probability was . for hospitalizations and thus . for recovery. and similar to the last sub-section, the parameters for the hospital recovery and death rate were also assumed directly connected as a hospitalized person would either recover or decease. therefore the hospital recovery rate was exactly the opposite portion of the death rate, yielding since the death rate for people already hospitalized is much higher than the death rate of the virus in general, it was calculated based on the number of confirmed deaths and hospitalizations also provided by the city of new york [ ] , which resulted in a death rate of . and hence a hospital recovery rate of . . and the first positive covid- case was reported in new york city on march st . unfortunately, this is only the first confirmed positive case and not necessarily or likely the first case in general. throughout the spread of the virus, only cases tested positive were reported and therefore a lack of people who carry the virus, but are not aware, has to continuously be assumed. this is further exacerbated by the fact that it is possible to carry the virus without ever showing symptoms [see ] . thus, the number of covid- cases resulting from a simulation has to be way higher than what the real data represents. actual numbers and estimation for the unknown numbers are hard to find and estimations range from over percent unknown cases [ ] to ten times the confirmed number or more [ ] . therefore, the number of unknown cases in the model was adjusted so that the model aligned from march st to march th with the reported real time data. in order to achieve this, the model was set to infections at the time of the first reported case. this lead to a realistic outcome of the simulation and also served as verification of the design as the fatality rate and the case numbers correlated with the data when taken into consideration the unknown cases. with these settings and parameters, the scenarios for the simulation could be run and evaluated. since the measures and regulations that were put into place are hard to quantify, the first scenarios will address the effects of such measures and show how they could have affected the numbers. then, the ensuing scenarios will evaluate possible future occurrences and possibilities. the following fourth section will cover these scenarios and therein discuss the general effects of the variable in the simulation, the effective contact rate. the fifth section then will discuss and show a possible and presumably likely phenomenon that could await in the near future, including its implications. as described above, the first baseline scenario to assess is to figure out what trajectory the real world data most likely followed in order to understand what the measures that were put into place changed and how they affected the model. as mentioned, the variable to be manipulated will be the effective contact rate which directly affects the infection rate. the first measure that was put in place in nyc was social distancing and the closing of certain institutions and stores to be implemented immediately. this was accompanied by companies moving employees to work from home or stopping work all together. official orders for example went into place on march th and march st after the national emergency was declared on march th [see ]. therefore, the scenario below was constructed for the simulation to evaluate the effects. in a first run, the two dates were utilized to introduce step reductions in the effective contact rate of various heights and the effects on the infection rate were compared in form of a graph. figure looking at the outcome, we see that the different effective contact rate steps flatten the curve significantly and stretch out the infections. looking at the data as of april , which would correspond to the day in the simulation, the fatality count in nyc was , , which corresponds to the run above that included two steps with a reduction of each time. unfortunately, as figure and show, this version of scenario does not do well as far as the reduction of the infection rate goes over time and the fatalities keep increasing exponentially despite the measures. this is due to the fact that the reductions are not significant enough overall to have a helpful impact. furthermore, such a scenario, while plausible and possible, is not realistic since measures put in place do not go into effect at once and everyone adheres to them immediately at the time they go into effect. therefore, a continuous reduction is more realistic, which is why such a scenario will be presented and evaluated in scenario . the second scenario, as above alluded to, will evaluate the effects of gradually reduced effective contact rates over a number of days. this way, the rates decrease over time until they reach certain events or a limit, which is more realistic since people adjust to new circumstances and in this case regulations gradually over time. thus, the starting point of the regulations mentioned in the previous scenario was used to introduce effective contact rate reductions with a delay of one day. for example, the blue line in figure indicates a reduction of for the effective contact rate after day for consecutive days until the rate reaches . . steps of to . steps of to . steps of . to . steps of . to . all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint with this data, we can see that the run with the steps of . down to . is closest to reality and approaches the fatality number currently reported. furthermore, we see that the gradual reduction of the effective contact rate leads to a peak in the infection rate which then introduces a downswing and successive upswing albeit the latter with a lower gradient of the infection rate over time. therefore, we can say that the gradual reduction of the effective contact rate is an effective measure to control the epidemic and can even hedge the upswing of the virus spread, as shown by figure . so far, we have looked at baseline scenarios which behave the same way over time and have changes that are linear or follow a gradient. unfortunately, this is not at all the case in reality, as singular or short term relaxation in rules or temporarily making exceptions can cause major changes to the effective contact rate for a brief period of time. such events can be short ones that increase the effective contact rate momentarily, but also longer time periods that show an increase or decrease, such as seasons, for example [see ]. since the increases are more critical than the decreases, we want to take a look at them in this section. at the time of this writing (april , ), easter is happening and during these times, various other religious holidays have happened or are coming up in the near future. during such holidays, people tend to congregate, visit religious gatherings such as masses, and visit family members. after a prolonged period of solitude, the perceived need and yearning for such close contacts increases understandably and there have already been reports of planned gatherings [ ] , measured significantly increased mobility in germany [ , ] , and people (including two of the authors) have witnessed good friday gatherings at homes in new jersey and new york, for example. these phenomena raise the question what could happen if people are giving in to their yearnings and defy recommendations and regulations. hence, this section will look at possibilities in two scenarios to estimate the implications of such defiance in order to enable a prediction regarding the outcome if the cause cannot be prevented. scenario will assess the possibility of increased effective contact rates on separate occasions and scenario will assess short periods of increases. as a basis for the scenarios, the trajectory closest to reality of scenario will be utilized. to utilize a real life example we simulated the run from scenario with the steps of . down to . and implemented two short increases in effective contact rate for good friday and easter sunday. in order to simulate various severities of increases, four runs were conducted with increments of % yielding the last run as a return all the way back to the effective contact rate c of . . the results are depicted in figure through on the next pages and discussed hereinafter. the figures through on the next two pages demonstrate the effects that short outbursts can have and a few takeaways have to be mentioned and pointed out. first, a return to the effective contact rates of a "normal" state can increase the infection rates temporarily by % as the first day with increased effective contact rates amplifies the second one. this is due to the decrease in between those two dates not being sufficient for the measures to fight back the short upswing in a limited time. therefore, these two increases could yield hundreds of thousands of new infections and thus could also even double the number of hospitalized patients. second, in the long run, these short increases in effective contact rates can have detrimental impacts when it comes to the fatality numbers as a result of the increased hospitalizations. in the worst case, this could lead to an increase in fatality numbers of % after days, not taking into consideration that hospitals might be overloaded and forced into triage procedure where limited resources have to be allocated and decisions have to be made which patients can receive treatments at all. overall, this scenario shows that singular increases already can have detrimental impacts and make the difference between hospitalization infrastructure being overloaded or able to handle the demand. in addition, the simulation shows the numbers immediately, whereas in reality, the incubation time might lead to a delay and thus the individuals infected over easter could potentially affect the medical infrastructure one week to two weeks later. with these aspects in mind, the last scenario will assess the worst possible option, a temporarily sustained increase, beginning on page . all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . rate -hospitalizations showing how many people require hospitalization for scenario each day after the delay of the incubation. this represents the required hospitalizations, which may exceed the real capacities of the hospitals and therefore cause shortage and possible even triage situations as described before. the predicted hospitalization numbers allow for estimation of necessary resources for the simulated area. reference % % % % all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . the above descried scenario assessed short singular increases, which might happen again in the future for certain events. this leaves the question though, since the last scenario already showed an interplay between two singular increases, how sustained increases, even if temporarily limited to various days, affect the numbers and if the reciprocity effects multiply. therefore, this last scenario assesses a constant increase over easter weekend, for example, if people would spend multiple days with family or other gathers, which is not unusual. again, in order to simulate various severities of increases, four runs were conducted with differences of % yielding the past run as a return all the way to the effective contact rate of . for three days (good friday through easter sunday). the results are depicted in figure through on the next pages and discussed thereinafter. figure shows the hospitalizations over days for demonstration purposes. the figures resulting from the last scenario show that the effects are partially as to be expected based on scenario since the infection rate steadily rises with every day the increase persists and therefore the impact that the measures have when they are back in effect is also reduced. for example, for the infection rate on the first day after the increased period, the numbers are between % to % higher than they were in the respective runs of scenario . this means that each day the increase persists will have permanent effects on the infection rates even once the effective contact rate goes back down. this permanent influence can have extreme ripple effects for the hospitalization and fatality numbers as shown by figures and below: the hospitalization numbers are between . % to . % higher than the respective runs of scenario and between % and % higher than the reference run; the fatality numbers are between . % to . % higher than the respective runs of scenario and between . % and % higher than the reference run over days. all in all, we can see that a temporarily sustained increase not only increases the numbers and therefore causes effects over the time of its existence, it also affects the numbers after its subsidence as it permanently increases the severity of the pandemic. this allows for two conclusions: one, it is imperative to prevent such increases at any costs and two, if they are inevitable, they have to be kept as low and short as possible to minimize the permanent impact they have. this concludes the simulations and scenarios assessed in this research. the last section will give a overview and summary including a conclusion and outlook regarding future research opportunities and plans. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint the previous sections have shown that the effects of such a dynamic and complex systems as this pandemic are by no means linear and predictable by mere extrapolation. even with the measures and the current standings, short increase and maybe even returns to "normal" effective contact rates can have detrimental outcomes that cause permanent effects impossible to cure even when caught early. the two simulation scenarios and demonstrated that even single short increases can show these behaviors and temporarily sustained ones increase and amplify the impact through reciprocity. our simulations have shown that increases permanently increase infection rates after subsidence by as much as % and higher surges, such as a return to "normal" and therefore % increase of the effective contact rate would increase the infection rate temporarily by over , %. these effects ripple through the system and impact hospitalizations and ultimately fatalities, increasing the former by as much as % at the peak and the latter by as much as % in the worst case compared to the references without contact increases. in numbers, given that increases of % and % seem to be most likely given the data seen in germany for the easter weekend for example [ , ] , our simulations show the following increases (compared to realistic reference run) for a temporary % surge in contact rate: the total cases grew by , , the maximum of required hospitalizations over time increased to , , and the total climb in fatalities was , accumulated over days. as for the % surge, we saw the total number of cases rise by , , the maximum number of required hospitalizations increase to , , and the total number of fatalities climb by , over days in nyc. in conclusion, the numbers and scenarios demonstrated that increases of any kind have to be prevent at any costs in order to not permanently impact the progress of the pandemic containment. if such increases cannot be prevented, it is imperative to keep them as short as possible and, if necessary, separate the peaks as much as possible in order to allow for regulation and mitigation in between. furthermore, other mitigation strategies such as stricter regulations could be a possibility to mitigate already happened singular increases. as described in the previous section, the results obtained in this simulation possess a certain predictive power within their numbers as they show possible phenomena, such as increases infection rates and their implications, before they develop effects in reality. this is especially important when it comes to the hospitalization rates, as increases infection rates or even short phenomena such as the described easter blip can significantly impact the hospitals in reality. thus, the results allow a predictions to an extent when a wave as a result of an increase in infection numbers might come. this can allow authorities to assign resources accordingly or at least prepare for possible impacts especially since data seen in reality already shows the trajectory of the evaluated scenarios [ , ] . as for future research and an outlook, other measures and effects, such as protective gear for the public can be assessed, as they might reduce the infectivity and or effective contact rate for example. this would allow for a selective use of such measures wherever necessary in order to purposefully utilize their effects. moreover, other branches and population areas are planned to be researched, such as emts and police, as the impact of the pandemic on such forces is also important for the general public safety. we see that the current pandemic impacts all our lives and will most likely continue to do so for, as of the time of this writing, an unexpected future. fortunately the research conducted allows simulation and mimicking of the reality with predictive power and we will continue to adjust our models to include any new and important occurrences. staying home and social distancing are our most powerful weapons in fighting this pandemic, but they only work if everyone participates, wide spread individual exceptions cannot be granted nor accepted and they can sabotage the whole mission. let's all do our part and participate in the fight, everyone can and everyone has to! stay safe, stay home, stay healthy! all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint coronavirus disease (covid- ) pandemic covid- -mobility trends reports deutsche sind immer mehr unterwegs states are restricting easter gatherings amid covid- . churches and lawmakers are pushing back world health organization gisaid: global initiative on sharing all influenza data -from vision to reality genome composition and divergence of the novel coronavirus ( -ncov) originating in chinacell a contribution to the mathematical theory of epidemics differential equations and mathematical biology vensim software introduction to modeling and simulation city of new york. www .nyc.gov/site/planning/planning-level/nyc-population/currentfuture-populations.page modelling transmission and control of the covid- pandemic in australia covid- update: transmission % or less among close contacts bioterrorism: mathematical modeling applications in homeland security. philadelphia, pa: society for industrial andapplied mathematics means of transportation to work by selected characteristics city of new york. www presumed asymptomatic carrier transmission of covid- estimation of covid- outbreak size in italy based on international case exportations the total number of italian coronavirus cases could be ' times higher' than known tally, according to one official what's closed? what's mandatory? how tri-state covid- action affects daily life recurrent outbreaks of measles, chickenpox and mumps: i. seasonal variation in contact rates key: cord- - mossbr authors: andrle, michal; hebous, shafik; kangur, alvar; raissi, mehdi title: italy: toward a growth-friendly fiscal reform date: - - journal: econ polit doi: . /s - - - sha: doc_id: cord_uid: mossbr published in late , the italian medium-term fiscal plan aims to achieve structural balance by , although concrete, high-quality measures to meet the target are yet to be specified. this paper seeks to contribute to the discussion by ( ) assessing spending patterns to identify areas for savings; ( ) evaluating the pension system; ( ) analyzing the scope for revenue rebalancing; and ( ) putting forward a package of spending cuts and tax rebalancing that is growth friendly and inclusive, could have limited near-term output costs, and would achieve a notable reduction in public debt over the medium term. such a package could help the authorities balance the need to bring down public debt and, thus, reduce vulnerabilities while supporting the economic recovery. italy has been struggling with low economic growth since the s. productivity growth has been persistently anemic and has lagged that of the euro area-see anderson and raissi ( ) , andrle et al. ( ) , bugamelli and lotti ( ) and the references therein. held back by long-standing rigidities, the economy failed to take advantage of euro accession to modernize its institutions or adapt to a changing global trade and technological landscape. pellegrino and zingales ( ) attribute the weak productivity growth in italy to the lack of meritocracy in the selection and rewarding of managers, and the inability of firms to take full advantage of the information and communication technology revolution. akcigit et al. ( ) argue that political connections adversely affected firm dynamics, innovation, and creative destruction in italy, weighing on the economic growth. moreover, wage growth outpaced productivity growth, contributing to high structural unemployment; see kangur ( ) . easy access to finance pre-crisis boosted demand, but the double-dip recession earlier this decade and the subsequent tightening of credit conditions set italy back further; see doerr et al. ( ) , and mohaddes et al. ( ) . implementing structural reforms are, thus, of greatest importance. high public debt and an inadequate composition of fiscal policy have also contributed to italy's underperformance. public debt, above % of gdp and the second highest in europe, has been a perennial source of vulnerability-see reinhart and rogoff ( ) and chudik et al. ( chudik et al. ( , who consider the consequences of high and rising public debt on economic growth. italy has run primary fiscal surpluses that on average were higher than its euro area peers, but these were insufficient to lower debt and secure stability. the quality of fiscal policy has also insufficiently supported inclusive growth. the burden of high taxes has fallen on labor, public investment has been squeezed, and social benefits have centered on generous pensions. aiming for an adequate primary surplus to reduce debt, underpinned by high quality pro-growth and inclusive measures, is thus also important. this paper contributes to the debate by identifying growth-friendly and inclusive options for achieving fiscal balance that could potentially put italy's public debt on a firm downward path. firstly, it discusses public spending trends and composition. an analysis of spending over the past two decades reveals that: ( ) in the decade following euro accession, spending grew faster than potential output, owing in large part to the rapid growth of pensions; ( ) since the global financial crisis, spending has been broadly controlled, mainly through a freeze on hiring and wages and cuts in capital spending. pension spending though has continued to rise; ( ) despite the recent spending control, the pre-crisis spending excesses have not been reversed; and ( ) achieving sizable and durable expenditure savings may require lowering the large pension spending. improving the efficiency of health spending in some geographical areas could also lead to some savings. secondly, the paper analyzes the italian pension system. over half of current primary spending is social benefit expenditure, which is dominated by pension spending. at around % of gdp, pension spending in italy is the second highest in the euro area after greece. the italian authorities have legislated several reforms in the past. however, before the full effect of these reforms is evident over the very long run, fiscal pressures are likely to persist and weigh on italy's goal of achieving and maintaining a balanced budget. the second part of this paper finds that: ( ) despite past reforms, there remain generous parts of the system where italy is an outlier, pointing to areas of potential savings; and ( ) pension projections rest on optimistic assumptions of (a) employment, specifically that italy will go from having among the highest to very low unemployment rates; and (b) italy will maintain much higher real gdp growth rates for decades to come than has been its experience and policy settings. relaxing these assumptions implies a notable rise in projected spending over the coming decades until the full benefits of past reforms become evident. thirdly, drawing lessons from the literature and cross-country experience, it discusses options for revenue rebalancing in italy. the tax system is characterized by a high tax wedge, a relatively narrow tax base, and significant tax arrears. a fiscal devaluation strategy-a shift from taxing productive factors to taxing consumption and property-reveals the scope to ( ) decrease the tax wedge significantly; ( ) reduce value-added tax gaps (both compliance and policy), by harmonizing the reduced vat rates and improving the tax collection performance; ( ) rationalize tax expenditures; and ( ) raise revenues by re-introducing a modern property tax on primary residences. fourthly, it simulates, using the imf's global integrated monetary and fiscal (gimf) model, the impact of a growth-friendly and inclusive mix of spending and revenue measures along a gradual fiscal consolidation path that puts italy's debt-to-gdp ratio on a firm downward trajectory-see kumhof et al. ( ) and anderson et al. ( ) for modeling details. the model simulations show that a revenue-neutral and less distortionary tax reform, alongside current spending cuts and capital spending increases, can generate sizable output gains and a sustainably lower public debt ratio over the medium to long term. short-term output costs of this fiscal package, if implemented credibly, are likely limited. the rest of the paper is organized as follows. section discusses italy's public spending trends and composition. section analyzes the pension system and identifies certain areas that can be improved. section considers some options for revenue rebalancing. section conducts a simulation exercise to assess the macroeconomic effects of a growth-friendly mix of spending and revenue measures. section concludes. over the past two decades, primary spending in italy has grown faster than potential output. this was particularly the case in the years after euro accession. from to , italy's nominal current primary expenditure grew faster than the euro area average, and well above the country's average nominal potential growth-driven mainly by social benefit spending (primarily pensions), intermediate consumption (goods and services), and wages (in general services, defense and health). capital spending rose in line with that of the euro area average. from to , however, italy's nominal current primary expenditure grew at . % per year on average, below the euro area average of . %. the deceleration after the global financial crisis was driven mainly by the decline in the public sector wage bill-reflecting the freezing of nominal wages from to and a reduction in the number of public sector employees from . million in to around . million people in ; and a severe cut in capital expenditure, which declined by about % in nominal terms between and . nevertheless, even with these exceptional measures, total primary spending grew above the country's average nominal potential gdp growth over this period. italy has been unable to reverse its past overspending (especially those related to the pre-crisis period). the high cost of servicing public debt implies total public expenditure in italy about % of gdp above the euro area average (at . % of gdp versus . %). interest on debt ( . % of gdp in ) absorbs more resources than spending on education ( % of gdp), and is over ½ times as much as on defense ( . % of gdp). social benefits have dominated all other categories of spending, rising by about % cumulatively from to and by a further % since then. it constitutes half of total primary spending, up from % at the time of euro accession. the bulk of social benefits spending is in pensions (see sect. ), reflecting both a high share of elderly population and generous pension benefits. however, non-pension social benefit spending in italy is low, fragmented, and poorly targeted in comparison to other eu countries. the latter is evidenced in the disproportionately low share of social transfers accruing to the low-income working age population. there is also a higher reliance on intra-family transfers for social assistance, even as there is underspending related to social inclusion, family/child benefits, and housing relative to the euro area average. a decomposition of spending-using standard economic and functional classifications at the general government levels ( table )-reveals that, apart from pensions: ( ) interest payments exceed the euro area average by . % of gdp, given italy's high stock of public debt. ( ) other areas of overspending include intermediate consumption spending (primarily on goods and services) in the health sector; compensation of employees in defense, public order and safety, and health; subsidies in the economic affairs sector; and capital transfers in general services and economic affairs. ( ) it is notable that although overall public health spending in italy is in line with the euro area average, the bulk of it is for compensation of employees and intermediate consumption, in contrast with the euro area average where the share of spending on these two items is significantly lower and that of expenditure on provision of other social benefits is % higher. this points to room for potential efficiency savings, especially in some regions. medeiros and schwierz ( ) table italy and euro area: general government spending, - , and highlight regional differences and show that the output of public spending is lower in southern regions based on health-related variables, such as life expectancy at the age of . ( ) the main areas where italy underspends is in education (i.e., in the provision of goods and services and in total compensation). the public education expenditure gap is especially concentrated at the tertiary level, as highlighted in oecd ( a, b) . as for economic classification, underspending is largely in gross capital formation (fig. ) . there is, therefore, room to improve the spending mix to make it more growth friendly and inclusive. the above simple presentation indicates that rising social spending (primarily pensions) has crowded out spending in areas such as education and capital spending. achieving a more growth-friendly and inclusive spending policy mix, while making space to achieve the medium-term objective, will likely require rationalizing total social benefit spending; rationalization of non-pension social benefit spending; better efficiency in health spending in some regions; and reallocation of spending toward capital spending and education, while also improving the efficiency of outcomes in both areas. protection of the vulnerable could be further improved through complementary measures such as more intense use of active labor market policies and a modern social safety net; see imf ( ) for a proposal. following sharp cuts in capital spending and with the wage bill/gdp at its lowest in two decades, rationalizing social benefits spending appears unavoidable. in recent years, the authorities have pursued a strategy of notably cutting capital spending and curtailing the wage bill, which at . % of gdp is at its lowest level in several years. this strategy may be close to its limit, however, and may be neither sustainable nor desirable. there is a need for public investment to support stronger, sustained growth. moreover, as a share of total employment, public sector employment is below the euro area average; the age structure of public employees is titled toward older workers, implying the need to refresh the skill mix without reducing the headcount further (there have been recent announcements for hiring sizable numbers of new staff, in education and local offices); and, after years of wage freezes, wage increases are planned. this suggests limited room, if any, for further cuts in the overall wage bill or in capital spending, going forward, and thus for little alternative but to tackle the sizable social benefits spending (fig. ) . since , the italian pension system has undergone multiple reforms. these include pro-rata replacement of the old defined benefit (db) scheme with a notional defined contribution (ndc) scheme ( , tightening of eligibility requirements ( , , , , , ) , alignment of the statutory retirement age of women with that for men ( , ) , and indexation of the retirement age to life expectancy. the transition from the old db system to an ndc scheme divides pension beneficiaries into two categories: ( ) those with at least years of contributions by end- will largely maintain the db formula. for this group, the old pension rules are grandfathered for contributions accumulated until . for contributions accrued after , the ndc scheme applies. ( ) those with less than years of contributions by end- are subject to a pro-rated scheme. for this group, contributions accumulated up to will be subject to the db formula, whereas contributions accumulated after will be subject to the ndc scheme. the average contribution period in italy for new pensions is about years (expected to increase to years) and life expectancy at is about years. thus, by about , all new retirees entering the pension system will be fully subject to the ndc formula, whereas by about , the old db should be fully phased out also from the stock of existing retirees. eligibility requirements have been tightened considerably in a series of reforms, notwithstanding repeated attempts to weaken them. both statutory and early retirement ages are set to increase further over time as part of the 'fornero' reform (l. / ). currently, the statutory retirement age (sra) is years and months. early retirement is allowed regardless of age based on minimum years of service of - years. under ndc, workers may retire up to years earlier than the sra with minimum years of contributions and a pension of at least € per month. from onwards, the eligibility requirements are linked to changes in life expectancy at (every years up to and years starting from ). occasionally, pathways to early retirements were eased or implementation of stricter rules were postponed (e.g., the and budgets). the experimental "quota " early retirement rule, introduced in , created a discontinuity in the retirement age that needs to be addressed. in general, special treatments and incentives for early withdrawal from the labor market should be avoided in both db and ndc schemes (see also imf ). following the 'fornero' reform, the pension system ( ) adopts an actuarial computation of pension benefits using an implicit rate based on the accrued contributions, and automatically adjusted to mortality developments; and ( ) introduces periodic increases in all eligibility requirements in line with longevity developments. according to the quota rule, workers who are at least years of age with a minimum years of contributions are eligible for early retirement during - . women who are at least years of age with a minimum years of contributions are also eligible. automatic adjustments of the statutory retirement age to life expectancy were canceled for - . the existing db scheme is overly generous on many accounts: ( ) it uses a weighted average accrual rate of % (mef ) that is multiplied by the years of contributions and the reference wage (pensionable earnings) to obtain the monthly pension benefit. an accrual rate of % is high by international comparison, compared to about . - . % in the eu/euro area. ( ) for insurance years before , the reference wage is defined as the last monthly wage for civil servants or an average wage of the last - years in the private sector, based on different sources and occupations. for contribution years after , the number of annual wages involved in the calculation increases gradually until it covers the last years for employees and the last years for the self-employed. but the periods over which pensionable earnings are calculated are still too short and tend to inflate the pension benefits of the db scheme. on the other hand, the ndc (by definition) covers total lifetime contributions. under the db scheme, the early retirement penalty is % at the age of , % at the age of , and a further p.p. for each year below . these penalties are rather lenient- queisser and whitehouse ( ) calculate that, for italy, the actuarially neutral reduction in benefits for each year of early retirement is in the order of . %. as a result, the replacement rates under the current db/mixed scheme are high compared to other countries and place the adjustment burden disproportionately on future retirees (chart). the difference from the euro area average, according to european commission ( ) , is around % points. the simplest solution would be to reduce spending in db/mixed schemes equivalent to the thirteenth pension payment (i.e., the christmas bonus) that would constitute a . % cut in average pensions of the db component. another option that would improve intergenerational fairness is to recalibrate existing pensions based on the steady-state ndc formula or equivalent accrual rates. regarding the ndc scheme, although it can screen out many past excesses, the annuity factor is based on a too high internal rate of return (irr). in a "pure" ndc, the irr should be chosen to ensure actuarial balance between the system-wide assets and liabilities ("annex"). in steady state, the irr converges to the rate of economic growth. while in the italian ndc the irr that credits the notional capital each period is the moving average of nominal gdp growth over the past years, the discount rate used to derive the annuity factor, defined as the ratio of the irr to a rate of inflation indexing, is set at a rate of . %, based on an expected longrun real growth rate. absent comprehensive and decisive structural reforms, such a real rate of return is considerably above italy's current growth potential. in the italian pension system, the adjustment to macro-demographic conditions (such as the periodic revisions in the transformation coefficient) affect future generations of retirees only, leaving current retirees unaffected. the irr that credits the notional capital is linked to past performance. it would therefore be important to introduce an automatic adjustment (or sustainability) factor that links current pension payments to a measure of a long-term actuarial balance to shield against unforeseen shocks and improve intergenerational equity (see barr and diamond, , for a discussion on such a "break" mechanism in sweden). at around ¾% of gdp, spending on survivor pensions is the highest in the europe. according to eurostat, the average monthly survivors benefit per inhabitant (at constant prices) in italy was € compared to about € in the euro area in -the second highest in the euro area after luxembourg and the third highest in europe after luxembourg and denmark. similarly, survivor pensions in italy have very wide coverage: the number of survivor pensions forms about % of total pensions in italy and is much higher compared to about % in the eu on average. the eligibility for a surviving spouse in italy does not appear to be constrained by an age limit, the absence of which can also dis-incentivize return to the labor market, especially for women. survivor pension payments to family members other than surviving spouse or orphans should be strictly limited. revenues collected from the self-employed could be increased. at %, the pension contribution rates on wage earners are high. of the contribution rates on wage earners, about one-third is borne by the employee and two-thirds by the employer. for the self-employed and farmers, the contribution rate in was . %, set to increase to % by . one explanation for the difference in the contribution rates for employees and self-employed relates to differences in the gross base: for the selfemployed, the gross contribution base includes all contributions whereas for workers only one-third (the employees' share). however, even then, the "neutral" contribution rate for the self-employed should be at least %. the self-employed in italy exhibit below average revenue productivity compared to their peers in the euro area. this is indicative of the need to further harmonize the contribution rates as well as strengthen collection and payment compliance. the tax burden on pensions is favorable to retirees. according to the oecd ( ), both the gross and net replacement rates in italy are on average about % points higher than for the oecd average retiree. the extension of the non-taxable area for retirees, as was the case in the budget, will further widen the gap. compared to wage earners, retirees in italy are subject to preferential tax treatment in terms of a higher tax-free allowance and full exemption on health contributions on pensions. compared to retirees in other oecd countries, italy offers tax relief on pension income from private schemes. deviations from general rules and partial reform reversals can also undermine past reforms. for example, the provisions in the budget for an annual fourteenth pension payment to low-income persons and higher tax-free thresholds for pensioners are costly and depart from actuarial fairness. moreover, in january , early retirement rules were eased notably. workers who are at least years of age with a minimum years of contributions have become eligible for early retirement. women who are at least years of age with a minimum years of contributions are also eligible. moreover, automatic adjustments of the statutory retirement age to life expectancy were canceled for - . such a reversal of past pension reforms would raise the number of pensioners, lower labor force participation and potential growth, and add to an already high pension bill. although the ndc in the long run is expected to reduce pension spending, by itself it is not enough to deal with italy's fiscal problems. according to oecd ( a, b), future gross replacement rates in italy would remain one of the highest in the oecd (text chart) with both gross and the net replacement rates about - % points above the oecd average, depending on the average pensionable wage. similarly, european commission ( ) projects italy's pension spending to remain more than % of gdp above the average of other european countries. this is partly due to many features described above, including high discount factor, survivor pensions, and transformation coefficient for women with children, but also due to the very high pension contribution rate of %. rapid aging will also put strong pressure on spending on health and long-term care that, according to european commission ( ) , is expected to increase by about ½% of gdp by (net of lower spending on education). in the latest report by the department of the state accountant general (rga) of the ministry of economy and finance, long-term pension spending is projected to remain subdued, supported by the implementation of the above-mentioned past pension reforms and strong recovery in employment and productivity. according to the rga ( ) projections, pension spending as a ratio of gdp is expected to increase from . % in to just above % in and decline afterwards, reaching . % by . based on these findings, the pension system and overall public debt are understood to be sustainable over the long term, and it is argued that italy is in much better stead than many other euro area members that have still to come to terms with age-related spending. there are several offsetting factors that contribute to these projections. firstly, the rga notes that adverse demographic trends as captured by rising old-age dependency are the main drivers of future pension increases, adding about ½% of gdp to pension spending by . secondly, over the next decade, until , the benefit rate-the ratio of average pensions to gdp per worker-is expected to increase pension spending, owing to the generosity of the old though declining db component compared to low productivity growth. thereafter, the share of retirees under the ndc scheme is projected to become sufficiently large to dominate the more generous older db scheme, settling the benefit rate on a modest downward trend. thirdly, the strongest savings in the rga's projections stem from a sizeable pick-up in the employment rate, with a notable increase in labor force participation and a substantial decrease in unemployment, as well as from reforms to restrict early retirement and extend retirement ages (eligibility rate)-reducing pension spending by about ½ and % of gdp over the long-run, respectively. with the unemployment rate reaching as low as . % of gdp by (and remaining steady afterwards), italy is expected to move from one of the worst to among the best performers in the labor market. relaxing some of the optimistic demographic and macroeconomic assumptions suggest spending would be notably higher (fig. ) . the simulation results indicate that for the rga ( ) projections to materialize, the ndc system must cut average pensions of future retirees further by about ½% of gdp (or by more than by %). the increase in the employment rate for the - age bracket in rga ( ) appears optimistic, based on current policy settings. it increased from % in to ½% in , driven largely by a decline in the unemployment rate to about . % by . however, italy's long-run average unemployment rate has been around ½%. assuming italy's unemployment rate settles at %, which implies an increase in the employment rate to about % in the long-term, the total pension spending increases by ½% of gdp by (solid red lines in fig. ) . with strong employment recovery, the authorities are also expecting per capita real gdp and real labor productivity to grow at around ¾% annually, far above what has been observed for the last few decades. such projections appear very optimistic. lower tfp growth would lower gdp growth immediately but would impact pension benefits slowly-through wages that pass through to lower contributions and thus lower notional stock of pension capital. according to the rga ( ), . % points lower labor productivity growth would lead to about . % of gdp higher pension spending in both and , whereas . % points lower tfp alone would increase the pension spending to gdp ratio by . - . % of gdp, respectively. in response to a permanent negative labor productivity shock (of about ½% points per year), our simulations suggest that pension spending would be about % of gdp higher in both and (red long dash lines in fig. ) . the population projections by the united nations population division point to more rapid aging in italy compared to demographic projections with base year recently published by istat, increasing the long-run pension spending further by about % of gdp at peak (red dotted lines in fig. ). the rga ( ) also reports an additional set of pension projections based on the ec-epc (awg) assumptions (with a steady state unemployment rate of about ½% as well as a faster achievement of % tfp growth by ). the result is an increase in pension spending by about % of gdp at peak (blue long dash lines in fig. ) when compared to the national scenario. in sum, taking more prudent assumptions for the employment rate, productivity growth, and demographics, which are closer to the historical record and based on current policy settings, pension spending as a percent of gdp is projected to reach . in (about % of gdp above the rga's baseline projection for ) before decline to . in (about ½% of gdp higher than rga's baseline projection for ). consideration should be given to enacting measures that would yield savings in the near term and secure savings over the medium term, consistent with current policy settings. near-term savings come from addressing the excessive generosity and lack of actuarial fairness in the db and mixed schemes, and several options to a temporary negative labor productivity shock of the same size (over the period - ) though would result in a . % of gdp higher pension spending between and before the impact of the shock fades away. cross-country as well as italian experience suggest that pension reforms may face political opposition (e.g., france) or sometimes can run into institutional and legal boundaries, often manifested in constitutional principles such as equality and proportionality. an example is whether pension measures should apply to new retirees (i.e., on a flow basis) or to existing pensioners (i.e., impacting the stock). in some institutional settings pension measures can often be best implemented in a context of a coherent systemwide reform rather than in a piecemeal or ad hoc manner, affecting only certain categories of pensioners. it can also be easier-both from institutional and political perspectives-to implement pension reforms if they are based on well-established system-wide principles such as equalization of internal rates of return or actuarial fairness. for example, kohli and arza ( ) argue that reforms that involve stronger link between contributions and benefits may be more legitimate and easier to implement since, when compared to retrenchments or stand-alone parametric changes, these appeal to shared values and norms. pension reforms should also be clearly justified and accompanied by socio-economic and legal assessments. every effort should be done to clarify reform needs, that, inter alia, can involve improving system-wide equity or overall fiscal sustainability. this end are outlined below. these could go toward creating the room for achieving higher primary surpluses that italy needs to put public debt on a firm downward trajectory as well as to improve intra-generational equity by shifting the adjustment on retirees who thus far have been relatively better off. longer-term savings come from using more realistic (or conservative parameters) that guide long-term pension benefit calculations as well as ensuring actuarial balance. our results show that there is merit in: ( ) eliminating the fourteenth pension payment fully and the thirteenth payment with an equivalent reduction in annual benefits for all retirees in the db and mixed schemes. support for the most vulnerable-a justification provided for the introduction of the fourteenth pension payment to low income retirees in the budget-could be achieved through the social safety net, in particular a well-designed guaranteed minimum income scheme; ( ) introducing an age limit for a surviving spouse and limit any payments to relatives other than surviving spouse or orphan. this would restrict eligibility for a survivor pension, reduce spending, and incentivize labor force participation; ( ) recalibrating existing pensions based on the steady-state ndc formula or equivalent parameters for accrual rates and/or pensionable earnings. this would serve to reduce short-to medium-run pension spending by reducing benefits to those who have benefited from the generous db scheme. it will not affect the long-run steady-state spending (given by the ndc); ( ) harmonizing (effective) contribution rates of self-employed with those of wage earners. lower contribution rates for the self-employed constitutes preferential treatment. although from a system-wide point of view lower contribution rates in the ndc eventually translate into lower pension benefits, it reduces the financing available to the pension system in the payg system and is a source of unfairness. moreover, ( ) an option for reducing the high labor tax wedge-as part of a fiscal devaluation strategy-while lowering long-run replacement rates can rest on lowering employers' pension contributions. this not only reduces the tax wedge on labor for current workers, but also translates into lower future pension spending via the ndc scheme. however, this is not the first-best policy choice from the point of view of a fiscal devaluation when there is a tight (and actuarially fair) link between contributions and benefits that can be imposed by the ndc, since in that case pension contributions are effectively deferred savings that are less distortionary than other contributions (e.g., health) that are more redistributive in nature. this option could be considered if future pension spending cannot be reduced by other means. there is also value in: ( ) subjecting pension benefits to health contributions and realign the tax-free threshold with wage earners. retirees should not be burdened with pension or unemployment contributions, although they are relatively more frequent consumers of health services and therefore should pay health contributions. consideration should also be given to reversing the higher tax-free threshold for retirees introduced in the budget; and ( ) adjusting the ndc discount factor to reflect realistic growth potential and introduce an automatic adjustment mechanism that links pension spending to the long-term actuarial balance (as, for example, done in sweden, canada, and germany). the main purpose of such a mechanism is to allow for automatic adjustments in current pension payments as a response to permanent shocks, thus helping to keep the pension system solvent without a possible need to increase payroll taxes (that in turn would lead to increases in future benefits). the discount factor currently fixed at . % annually is well above the italy's long-term growth potential based on current policy settings. a key implication of the above simulations is that italy needs to pursue comprehensive growth-enhancing reforms as a matter of urgency to reduce nominal wage rigidities and increase productivity and long-run employment rates. in the absence of such reforms that will take time to yield gains and reduce existing imbalances, even the self-adjusting ndc cannot ensure the sustainability of the pension system and public debt. it would, therefore, be prudent to set the safeguards as well as the system-wide parameters to be in line with the economy's potential under current policies rather than the stronger growth rates assumed in the rga ( ) projections. such an approach would reduce the risk of needing to take painful, large adjustments over a short time and thus reduce policy uncertainty. the italian tax system has many aspects of a dual income tax (dit) regime. it applies a flat tax rate of % on capital income (dividends, interest income, and capital gains on securities), and % on rental income. labor income is subject to a progressive scale with a starting rate on the first earned euro of % and a top tax rate of % for income exceeding € , (the personal income tax is known as "irpef"). the corporate income tax (cit) rate, the so-called "ires," stands at %, but a surcharge of . % is imposed on financial and insurance companies. in addition to the ires, there is a "regional production tax"-an origin-based valueadded tax known as the irap-imposed as a fixed rate of . % on the net value of production. however, tax rates remain high and are applied on a relatively narrow base. total government revenues-at . % of gdp-compare favorably with the eu average of % (table ) . out of this, total tax revenues of . % of gdp in also compare favorably with revenues in the region. about high tax rates, it should be noted that the labor tax wedge is high-e.g., for a single person earning an average income it is . %, well above the oecd average of . %. this pattern is observed across levels of income and types of the essence of a dit regime is to tax capital at a low single rate and labor income under a progressive schedule. the % flat rate applies in the case of non-qualified shareholding. if certain thresholds' requirements are met, then . % of the (qualified shareholding) capital gains or dividends are subject to the progressive personal income tax scale. a reduced rate of . % is applied to the share of capital income deriving from state securities; and a tobin tax exists on financial transactions and stamp duties, consisting of taxes on stock of financial assets rather than incomes. ten percent of the irap paid during a year can be deducted from the ires. the labor cost for openended employees can be deducted from the irap tax base; there is a possibility for regions to reduce up to zero the tax rate of . % or increase it by up to . pp. the tax wedge is sum of taxes and sscs paid by employees and sscs paid by employers, minus family received benefits. the average tax wedge is the tax wedge divided by the total cost of labor for the employer. this measure can be computed at various levels of income and types of households (singles, couples, with or without children). the authorities plan to reduce the labor tax wedge by . - . % of gdp in - . this is to be implemented by extending the national income tax bonus (from € per month to € per month) in and potentially folded into a planned tax reform in . households. the ratio of the social security contributions (ssc) to gdp is . %, which is % points higher than the eu average. the share of personal income tax (pit) in total taxes is among the highest in the eu at %. the cit to gdp ratio is about %, well below the eu average of . %, even though the cit rate is significantly higher than the current eu simple cit average (excluding italy) of . %. with the irap, italian companies are taxed at an even higher rate. the standard vat rate is % compared to an eu average standard vat rate of about . %. about the relatively narrow base, it should be noted that tax expenditures are quite large, estimated by tyson ( ) at . % of gdp, and by the "commissione marè" report on tax expenditures at . % of gdp. a recent report from the ministry of economy and finance (mef) identifies measures of this kind on a legal basis. italy has one of the weakest performing vat systems in the eu, reflecting the presence of policy as well as compliance gaps. the vat c-efficiency-an indicator of the departure of the vat from a perfectly enforced tax levied at a uniform rate on all consumption-at about % is well below the eu average. combining this with a compliance gap of about %, as estimated by ec to be the fifth highest in eu, implies a policy gap of about % (the second highest in eu). moreover, the cit revenue productivity is only . % compared to the eu average of . %. alternatively, the implicit tax rate on corporate income in italy was . % in (the latest year available), as compared to . % for spain and . % for the uk. finally, tax evasion is very high. on average and over the period - , the amount of to reduce the labor tax wedge, italy has adopted several measures, including ssc exemptions, the € pit reduction, and deduction from the irap tax base of the labor cost of hires with permanent contracts. see keen ( ) for a detailed discussion of the c-efficiency measure. the policy gap can be further decomposed into those arising from exceptions and rate dispersion. a "fiscal devaluation" (see de mooij and keen ), support for investment, and a tax administration reform would make for a growth-friendly strategy. specifically, shifting the tax burden from labor income to less distortive tax bases would include (a) lowering employers' ssc rate to closer to the eu average; (b) using well-designed targeted instruments to increase labor supply; (c) introducing a modern property tax on primary residences and updating cadastral values; and lowering the vat policy and compliance gaps, e.g., by harmonizing the reduced vat rates, reducing the range of items subjected to reduced rates or exemptions, and considering a moderate increase in the standard vat rate; (d) eliminating inefficient tax expenditures (e.g., abolishing the mortgage interest tax credit); and (e) strengthening capital gains taxation by ensuring italy's right in the domestic law to tax capital gains from offshore indirect transfers of assets. investment could be encouraged through more effective, efficient, and credible tax provisions, building on measures such as adoption of an allowance for corporate equity (ace) regime since and several internationally-required anti-taxavoidance provisions. specifically, this strategy would include (a) streamlining targeted tax incentives to encourage innovation and r&d investment; (b) improving the design of ace, e.g., by providing a higher ace rate for start-ups; (c) abolishing the intellectual property (ip) box regime; and (d) improving the overall investment climate by addressing uncertainty in tax matters that dampen taxpayers' confidence and investment, e.g., by making the r&d tax credit permanent and credibly announcing the non-extension of enhanced depreciation. reforming tax administration, includes restoring autonomy to fiscal agencies, strengthening enforcement, relaxing legal constraints to tackle tax debt, and bringing instalment arrangements in line with international best practice. a "fiscal devaluation" is a revenue-neutral shift in the tax structure (e.g., from employers' social security contributions toward value-added and property taxes) with positive effects on output. reducing employers' sscs can stimulate labor demand in the short term. given wage rigidities and being in a monetary union with major trading partners, cutting employers' sscs can reduce labor costs (and producer prices, including those of exports) as well as increase labor demand in the short term. the resulting favorable effect on the trade balance could be temporary though, if nominal wages eventually adjust to fully offset the cut. however, the impact on employment and output may be longer lasting with a shift in the tax burden toward non-labor income (vat and property taxes) that is also less distortionary. moderately increasing the share of employees' sscs in total could, under certain conditions, partially finance the cut in the employers' ssc and ensure a stable stream of funding. changing the composition of the sscs by adjusting the employees' ssc share would address the risk of using general revenues to finance pension and social security obligations. however, there could be a negative effect on wages and labor supply, and thus the measure could best be introduced should the government decide to reduce personal income taxes and be complemented with other targeted measures. better use of targeted measures toward increasing labor supply, especially of low-income earners, is recommended. italy has the lowest labor supply of married women among eu countries. this is in part driven by a tax credit for non-working spouses that discourages their labor supply. a better design is to replace this with a tax credit if both spouses are employed (called working family, or in-work, tax credit), which can be increasing with the number of children (as, e.g., in the uk and the us). available evidence suggests that adopting in-work tax credits for low income earners, within a revenue-neutral reform, can have sizable impacts on the female labor-force participation and aggregate employment (saez et al. ; de mooij ) . for italy, colonna and marcassa ( ) find that replacing the dependent-spouse tax credit with an in-work tax credit increases married women participation rate by % points. however, although in-work tax credit alleviates the tax burden at the extensive margin, there is a risk of increasing distortion at the intensive margin of labor supply, which can be mitigated through an appropriate design of the in-work credit. re-introduction of a property tax on primary residences is a vital element of a modern tax system in italy. the municipality property tax (known as "imu") and the municipality tax on local services ("tasi") for primary residences were abolished in , owing to their unpopularity. the property tax is an efficient instrument and can raise significant revenues. in , recurrent taxes on immovable property raised . % of gdp in italy. even if taxes on primary residence were reintroduced, to fully exploit the potential of the property tax, it is essential to reform the cadastral system and update the cadastral declared value of the property on the rogito (deed of sale). using municipal property taxes to finance local governments enables the central government to reduce transfers to local governments and free up resources to fund the lowering of employers' sscs. lowering the vat policy gap by harmonizing the reduced vat rates can raise significant revenues. the vat compliance gap as of was € . billion, about % of total vat liability ( . % of gdp), significantly higher than the eu- average ( . %). halving this gap, while maintaining all tax rates unchanged, would increase revenues by . % of gdp. moreover, based on eu ( ), fully closing the policy gap, i.e., if no vat reduced rates and exemptions were applied, would enable italy to increase its vat revenue by an additional %. this estimate, however, is based on a full compliance scenario. adopting a lower number of reduced rates could be an intermediate step toward lowering this policy gap. decreasing the range of items subjected to reduced rates or exemptions is also important for lowering the policy gap. for instance, instead of exempting taxi services from the vat, they can be subject to the reduced rate; however, if taxis pay vat on their inputs, a careful analysis is needed to assess the revenue impact. tax arrears are at an alarmingly high level reaching € billion (as of ). toro et al. ( ) suggest that a significant amount of arrears is not collectable (e.g., because % of debtors are out of business or bankrupt and % relate to cases where enforcement actions were taken but did not result in actual collection) calling for effective write-off arrangements. recurrent tax concessions undermine voluntary compliance culture and the effectiveness of tax administration. about € billion of tax arrears is deemed recoverable. enforcement actions are critical that could be supported with timely filing, modern payment arrangements, and relaxing legal constraints. italy embraces a large set of tax credits in part reflecting income redistribution mechanisms. for example, within the personal income tax, there are tax credits for income sources, an € per month bonus, and family tax credits (including for dependent spouses and children). other allowances/deductions within the tax structure include substitute tax on capital income, ace allowances and participation exemption, reduced vat rates and compulsory payroll tax deductions. the largest item is the tax credits for income source. this item reflects the fact that the first bracket of income (from zero to € , ) is subject to a tax rate of %. these tax credits are reduced progressively until, at income levels above € , , they no longer apply. thus, this tax credit is warranted for redistribution. however, some other tax expenditures within the direct income tax should be revisited and could be gradually eliminated, including: ( ) mortgage interest tax credit. the tax credit is equal to % of the mortgage interest payments. the upper limit of this tax credit is € . since capital gains on primary residence in italy are exempt from the capital gains tax, and high household debt could be associated with stability risks (imf a), the mortgage interest tax credit should be phased out or at the very least its generosity should be lowered; and ( ) tax credit for medical expenses. this tax credit is equal to % of medical expenses exceeding € . . yet, redistribution motives in this area can be better-targeted using government expenditures, and furthermore, currently, health services are either subject to a reduced vat rate or exempted from the vat in italy. a simple and certain business taxation strategy is recommended that relies on two key elements: ( ) innovation and allowance for corporate equity, and ( ) removal of inefficient incentives. note that in the presence of ace, changes to statutory cit several measures were introduced in recent years to reduce the vat gap. examples include optional electronic invoicing, more frequent vat invoice transmissions, and split-payment and reverse-charge mechanisms. a analysis of the tax credit for medical expenses based on tax returns statistics show that the beneficiaries, mostly with incomes below € , , are . million for a total amount of € . billion of expenses. rates are less likely to impact investment decisions. the extent to which the revenue loss of the recent cit rate cut from . to % can be compensated by increased investment and growth depends on profit shifting and location choice. the lower cit rate can reduce incentives for profit shifting. however, this aspect is unlikely to be significant because, italy has agreed to comply with the atad and the g / beps minimum standards. these anti-avoidance measures help safeguard against profit shifting. the neutrality of the cit regarding ace means that any impact on investment will come in effect from changed location by multinational companies, but the location decision depends on several other tax and non-tax factors (including labor regulations and labor supply). firms that would have invested anyway would also benefit from the rate cut, adding to the fiscal cost but without benefit. ace contributes to very low, perhaps even negative, marginal effective tax rates, thereby positively impacting investment. effective tax rates summarize the impact of major elements of the tax base, such as depreciation allowances and the ace, along with the rate of tax itself. in theory, the marginal effective tax rate (metr)a measure of the tax burden on an investment that just yields the required rate of viable return-is zero in italy because the ace does not tax normal return. in the text figure, taken from the oxford center for business taxation, the metr is negative, suggesting that the marginal investment receives a subsidy in italy (although these calculations must be interpreted with caution as the negative rate is driven by strong assumptions underlying the calculations). another measure is the effective average tax rate (eatr), which is important for multinational companies' location choice for new affiliates (it measures the proportion of the present value of pre-tax profit that would be taken in tax). the eatr in italy compares favorably to several eu member states including spain, france, germany, and portugal. the impact of the ace on investment could be enhanced, for instance, by providing a higher ace rate for small businesses (perhaps contingent on an age requirement), re-linking the rate to government bond yields, and a premium to reflect risks, and introducing a minimum rate of - % in line with the eu common consolidated corporate tax base (ccctb) proposal to enhance tax certainty. well-designed r&d tax incentives can have a sizable impact on productivity. taxation can incentivize private r&d activities through the input side-in the form of an r&d tax credit or deduction-or the output side in the form of a reduced tax rate on ip income ("ip box"). while italy has measures on both sides, the former measures are more efficient. empirical evidence suggests that one euro spent by the government on r&d tax incentives, on average, increases domestic private r&d by one euro, whereas one euro spent on an ip box can, at best, increase r&d by less than one euro (imf b; dumont ) . bloom et al. ( ) estimate that a % reduction in the cost of r&d increases the level of r&d by about % in the short run and % in the long run. griffith et al. ( ) estimate that ip regimes have resulted in lower revenues from ip in the benelux countries and the uk not all eu countries adopt an ip box, while the tax rates for those that apply an ip regime are shown in the text figure. italy exempts % of qualified ip income from taxation, and taxes the within the supplementary budget, the base of the ace tax deduction was changed from "the increase in equity since " to "the increase in equity in the last years before the tax year considered". the strategy followed by italy to scale-up investment and enhance productivity includes: ( ) tax credits for r&d investments; ( ) accelerated depreciations, such as super and hyper-amortizations; ( ) subsides to smes to repay loans and agreements with banks to promote access to credit, as envisaged by the so-called nuova sabatini law; ( ) specific credits and crowdfunding for start-up and smes; ( ) tax allowances, such as ace; ( ) state guarantees on loans of smes; ( ) a reduced tax rate on incomes from the direct use or license for ip incomes (the so-called patent box); and ( ) targeted incentives to innovative start-ups. remaining % of that income at the statutory cit rate of % implying an effective tax rate of about %. in general, there are some concerns with ip boxes. the ip tax relief: ( ) rewards only success. successful r&d outputs are a function of many non-r&d related inputs (including management) that are not characterized with market failure. ip regimes may discriminate against potentially important r&d activities that may not be successful quickly. ( ) it is proportional to the amount of qualifying ip income, and not connected to the level of r&d expenditure. that is, two patents may generate the same income, thereby receiving the same benefits from the ip regime, even if they have different levels of r&d input. ( ) it cannot perfectly target the location of r&d. there is a distinction between the legal ownership of patents (and knowhow assets) and the location of r&d activities that led to the patents. ip boxes can influence the location of the legal ownership of the know-how assets (within the multinational group) with little effect on domestic r&d investments. essentially, large enterprises particularly in the manufacturing sector benefit the most from this scheme. options to streamline the existing r&d and investment incentives include: ( ) abolishing the ip box regime. the october european ccctb proposal envisages a super deduction for r&d expenditures. if implemented, the ccctb would phase out ip regimes. the supplementary budget attempts to harmonize the patent box regime to oecd standards. ( ) making the tax credit for r&d expenses permanent. ( ) credibly announcing that temporary super depreciation rules will not be renewed (starting from a given date). ( ) periodically assessing the effectiveness of the allowances for investment in innovative startups. potentially, this measure should not be size-based and apply only to startups. frequent changes to tax policy and administration, and excessive use of temporary provisions can be an important source of uncertainty (imf/oecd ). the frequency of tax changes in italy is high compared to other g countries, and introducing or renewing temporary measures with varying conditions is prevalent. temporary measures generate uncertainty when their expiry date is either unclear or not credible. such uncertainty risks creating a hold-up problem, as firms defer investment until the uncertainty is resolved. the imf's global integrated monetary and fiscal model (gimf) is used to illustrate the effects of the above-mentioned fiscal package. gimf is a multi-country structural dynamic general equilibrium model featuring italy, the rest of the euro area, and the rest of the world. it links the behavior of households, firms, and government sector within and among countries. the model has a consistent system of national accounting and stock-flow budget constraints for all sectors, including the government. the model belongs to exogenous-growth types of models, meaning that the long-term growth of output is exogenous. hence, all fiscal or structural measures may change only the structure of the economy, possibly increasing permanently the level of real output per capita; never long-term growth. the household sector consists of forward-looking optimizing households, as well as liquidity-constrained households who spend all their available income every period. the forward-looking households are modeled as overlapping generations (olg) with finite lives, following the blanchard-weil-yaari framework. the presence of olg households breaks the ricardian equivalence and is important for realistic results of fiscal policy in both the short and long run. households gain utility from consumption and disutility from labor effort, they consume traded and nontraded services and goods, receive labor income, transfers from the government, dividends from corporations, and pay taxes-income, consumption, and lump-sum taxes. firms produce intermediate and final goods using labor and capital inputs, accumulate capital, and import or export their production. firms pay taxes from corporate income. monetary policy in the euro area and rest of the world regions follows an inflation-forecast targeting rule to set policy interest rates. italy is a member of the euro area. government collects tax revenues (consumption, labor income, capital income, and lump-sum taxes) and spends them on government consumption, investment, and transfers to households. governments target specific debt-to-gdp (and thus deficitto-gdp) ratios and use a mix of instruments to achieve it. the government's commitment to sustainable public finance is credible for firms and households, who hold the stock of government bonds. the scenario modeled assumes a permanent fiscal consolidation of about ½% of gdp (in the structural primary balance) per year for years with the aim of achieving a small structural surplus in the medium term, supported by a pro-growth mix of revenue and expenditure reforms, and is compared to a trend or no-policy-change baseline. two types of growth-friendly revenue and spending measures are considered along the envisaged fiscal consolidation path: shifting taxation from direct to indirect taxes, and lowering expenditure and shifting its composition from transfers to investment. on the revenue side, a lower labor tax wedge ( . % of gdp) is offset by higher vat collections from reduced policy and compliance gaps ( % of gdp) and introducing a modern property tax on primary residences ( . % of gdp). on the expenditure side, spending on public consumption is lowered by . % of gdp, while productive public investment spending is increased by . % of gdp. the remaining portion of the fiscal consolidation, . % of gdp, is implemented via reduced social transfers. in the model-based analysis, it is assumed that higher public investment spending and an associated higher level of government capital exert positive spillovers on private sector productivity. finally, the marginal cost of borrowing, i.e., at issuance, is assumed to increase in the medium term from its average of . %. the -year italian government bond spreads vis-à-vis german bunds are assumed to decline gradually from an average of basis points in to basis points in , which is the average level of spreads over the past years. spreads are mainly driven by the evolving interest rate changes in italy as german -year bund yields are expected to remain low over the medium term. interest-rate spreads are expected to decline further in the long-term despite monetary policy normalization-given the quality of simulated fiscal adjustment and the gdp path in italy. the policy package would result in an output increase of around % and a lower debt-to-gdp ratio of around % points in a decade (fig. ) . the increase in output is even larger in the long run (around ½% higher than the baseline) while the debt-to-gdp ratio is more than % points lower than the baseline. for example, starting from % of gdp in , debt-to-gdp ratio would decline to % in years and gdp growth would be . % points higher per year. the positive response of the economy is a result of a less distortionary new tax structure, with lower labor tax wedges, and of the more productive spending, namely on public investment, and lower debt-service costs (implementation of this package would bolster investor confidence). lower taxes on capital induce firms to increase investment and raise their desired level for the private capital stock. lower labor income taxes encourage households to provide more labor. the net effect of lower income taxes and higher lump-sum as well as value-added taxes is positive on private consumption in the long term. the revenue-neutral tax reform on its own-with no change in the debt-to-gdp ratio-would result in higher private consumption and output owing to the economy moving towards less distortionary sources of taxation. the increase in productive public investment, lower public consumption and social transfers result in further output gains in the long run. the productive public spending stimulates private capital accumulation and the lower deficit and debt ratios result in significant savings on debt-service costs. in the short run, before the benefits of more productive investment and of lower debt fully materialize, the reduced social transfers and public consumption dampen somewhat private consumption and output. short-term costs though are quite modest and are traded for significant longer-term benefits of permanently higher private consumption and output. the fiscal consolidation/composition shift scenario assumes that the measures are gradually phased in over the period of years (½ of gdp per year). if the announcement of the reform is fully understood by firms and households and fully believed, the short-term costs are even smaller than in the case when the general public considers permanent only the measures implemented in the given year and in the past, but do not believe that future reforms will be implemented. when households and firms believe the whole path of fiscal reforms they invest more from the outset and reap the long-term benefits of the fiscal consolidation sooner. overall, the high quality of fiscal adjustment enhances the confidence about debt sustainability, hence, lowering the interest costs and offsetting the contractionary impact of a moderately-gradual fiscal tightening (see blanchard and other on contractionary fiscal expansions in italy). this contrasts with the italian experience during the european debt crisis for three reasons: ( ) the assumed adjustment in our simulations is more gradual; ( ) the quality of fiscal adjustment is improved; ( ) and fiscal multipliers are likely smaller because the output gap is narrower, and the public debt is higher. this paper contributed to the fiscal policy discussions in italy by: ( ) assessing spending patterns from a long-term perspective to identify areas for savings; ( ) evaluating the pension system; ( ) analyzing the scope for revenue rebalancing; and ( ) outlining a package of spending cuts and tax rebalancing that is growth friendly and inclusive. we showed that a comprehensive fiscal reform package predicated on a revenue-neutral and less distortionary tax reform, alongside current spending cuts and capital spending increases, can generate sizable output gains and a sustainably lower public debt ratio over the medium to long term. short-term output costs of this fiscal package, if implemented credibly, are likely limited. total liabilities are the present value of the sum of workers accumulated capital (k) and pensioners' annuity (na). total assets are the present value of the stream of future contributions (plus technical reserves). in practice, this true irr is only known ex post. however, it must be parameterized ex ante (to calculate the annuity) possibly based on the growth rate of the wage bill: where n is the growth rate of labor force (population) and g is the productivity growth. it is clear from eqs. ( ) and ( ) that the structure of the two systems is similar. when the rate of valorization in the db and the internal rate of return in the ndc system are equal (i.e., u = n) and the accrual rate (a) is equal the ratio of contribution rate to the annuity factor (c/g), the systems can, in fact, be identical. the main differences relate to the manner the schemes react to shocks and in available policy instruments to counter these shocks. in the ndc, pension benefits adjust automatically to shocks like a sudden decline in fertility (lower contributions) or an increase in life expectancy (that determines the annuity factor g). this is not to say that the db system cannot cope with such shocks; this could be achieved by linking the formulae or retirement ages to life expectancy for example. discretionary adjustments differ in terms of parameters that policy makers can control. examples of these in the ndc are irr computation rules, minimum retirement age, life expectancy tables, and methods to calculate annuity. in the db scheme, many such parameters are absent or non-discretionary; instead, policy-makers can control, inter alia, accrual rates or the way pensionable earnings are calculated. connecting to power: political connections, innovation, and firm dynamics. nber working papers getting to know gimf: the simulation properties of the global integrated monetary and fiscal model corporate indebtedness and low productivity growth of italian firms italy: quantifying the benefits of a comprehensive reform package l'efficienza della spesa per infrastrutture improving sweden's automatic pension adjustment mechanism do r&d tax credits work? evidence from a panel of countries - productivity growth in italy: a tale of a slow-motion change. bank of italy debt, inflation and growth robust estimation of long-run effects in dynamic panel data models. globalization and monetary policy institute working paper is there a debt-threshold effect on output growth? taxation and female labor supply in italy reinventing the dutch tax-benefit system: exploring the frontier of the equityefficiency trade-off fiscal devaluation" and fiscal consolidation: the vat in troubled times credit-supply shocks and firm productivity in italy evaluation of federal tax incentives for private r&d in belgium: an update the ageing report. economic and budgetary projections for the eu member states ownership of intellectual property and corporate taxation policy uncertainty and corporate investment italy's fiscal sustainability revisited tax policy, leverage and macroeconomic stability. imf policy paper, october (washington) fiscal policies for innovation and growth. fiscal monitor reforming italy's social welfare system and lowering taxes on labor: some considerations competitiveness and wage bargaining reform in italy the anatomy of the vat the political economy of pension reform in europe the global integrated monetary fiscal model (gimf)-theoretical structure efficiency estimates of health care systems in the eu -round of epc-wga projections-italy's fiche on pensions can italy grow out of its npl overhang? a panel threshold analysis economic survey of italy diagnosing the italian disease neutral or fair? actuarial concepts and pension-system design growth in a time of debt le tendenze di medio lungo periodo del sistema pensionistico e socio-sanitario. department of the state accountant general, ministry of economy and finance le tendenze di medio lungo periodo del sistema pensionistico e socio-sanitario. department of the state accountant general, ministry of economy and finance optimal income transfer programs: intensive versus extensive labor supply responses the rate of return of pay-as-you-go pension systems: a more exact consumption-loan model of interest social security programs throughout the world: europe enhancing governance and effectiveness of fiscal agencies reforming tax expenditures in italy: what, why, and how? imf working paper series acknowledgements we thank romain duval, rishi goyal, zsoka koczan, and roberto piazza as well as the italian authorities for helpful discussions and comments. this paper was written before the covid- pandemic. the views expressed here are those of the authors and do not necessarily represent the views of the imf, its executive board, or imf management. the italian pension system is currently prorated over the defined benefit (db) and notional defined contribution (ndc) schemes. as the names imply, a db pension plan provides a specified payment amount in retirement, while an ndc plan allows employees and employers to contribute and invest funds over time to save for retirement. key features of pure db and ndc pension schemes are explained below: the db system rests on four key parameters: ( ) the accrual rate (a), that is the pension entitlement for a full year's coverage as a share of earnings; ( ) a measure of earnings (w) that usually is lifetime average earnings; ( ) valorization factor (u), that is, the way how the earnings of earlier years are adjusted to reflect changes in standards of living between the year of retirement and these earlier years; and ( ) the retirement age (t). the benefit is then defined as: in the ndc system, each individual's contributions, (c), accumulate into a notional capital (in individualized accounts) that by end of any period (t) is:where ρ is the notional interest rate or the internal rate of return (irr). in computing the annuity (a series of equal payments) at retirement, the accumulated capital stock is divided by the annuity factor (g) that in turn is a function of life expectancy (le) at retirement and the irr:the irr in the pure ndc scheme is chosen to equalize the present value of system assets (a) with the present value of system liabilities (l), or:( ) ( + ) t−t , key: cord- -g mqsbct authors: sheldon, george title: unemployment in switzerland in the wake of the covid- pandemic: an intertemporal perspective date: - - journal: swiss j econ stat doi: . /s - - - sha: doc_id: cord_uid: g mqsbct the following contribution compares the unemployment situation arising from the lockdown induced by the covid- pandemic with previous employment crises in switzerland. in addition, it forecasts the future trajectory of unemployment based on ongoing changes in hazard rates. from a historical perspective, current unemployment as well as that expected by the federal authorities in the medium term do not seem that dramatic. current hazard rates present a different picture, however, predicting increases in both the unemployment rate and long-term unemployment to record levels. the impact on the swiss labor market of the lockdown that went into force on march , , in the wake of the covid- pandemic appears dramatic. roughly , employed lost their jobs on average in march and april after the shutdown. in just those months, the unemployment rate rose by almost as much as it increased in all of following the financial crisis. accordingly, the state secretariat for economic affairs currently expects the unemployment rate to average . % in the coming year, eventually reaching % if the shutdown persists, and this despite the fact that over a quarter of the employed are presently working short time to avoid unemployment. small wonder that some now fear that switzerland will experience the deepest recession in its history in the coming months. yet is the current labor market situation really as dire or unique as presently felt? after all, roughly , individuals report unemployed every january without any major repercussions. hence, strong surges in unemployment are not unheard of in switzerland. the following contribution aims to enlarge upon this cursory evidence with a more indepth study by comparing the current situation with previous employment crises and offering a forecast of the future trajectory of unemployment on the basis of a set of leading indicators that have proven their worth in the past. our results show that unemployment rates in excess of % are not unknown in switzerland, the most recent occurrence arising in the s. by decomposing the unemployment rates into its constituent flow components, unemployment incidence and duration, we further see that the lockdown has led to a new record with respect to incidence and almost equaled previous marks with regard to duration. in addition, forecasts of the future trajectory of the unemployment rate and the share of long-term unemployed based on the incidence and duration of unemployment prevailing in june imply that the unemployment rate will at least reach and perhaps even surpass the previous record set in the s and that the share of unemployed will clearly exceed previous milestones. resolved to break the high inflation stemming from an abandonment of the gold standard to finance the wwiinduced shortages and to return to the old gold standard. this led the inflation rate to drop from around + % in to the today barely imaginable level of − % in . the rapid rate of deflation caused the economy to collapse and the unemployment rate to soar to . %. years of relative prosperity followed thereafter before switzerland underwent the global depression in , which saw the average unemployment rate rise to . % in . the downturn did not last long, however, thanks in particular to the devaluation of the swiss franc and the military build-up supported by a large bond issue in . after wwii, years of strong and broad growth followed, in which unemployment virtually disappeared. in fact, a general labor shortage arose leading to a strong influx of foreign workers, which in turn caused the share of foreign residents to rise from . % in to . % in , a level last seen at the onset of wwi. however, it took years to reach that level in but merely years after the wwii. the postwar years of prosperity came to an abrupt end with the first oil price shock in / followed by the second one in . employment fell by almost % in the wake of the first shock, the largest job loss experienced by an oecd country in the wake of the first oil price crisis. nevertheless, the unemployment rate did not even reach the % mark. one reason is that mandatory universal unemployment insurance did not exist in switzerland until april . as a result, roughly % of the labor force was not insured against unemployment at the time of the first oil price shock, and without benefit claims, many chose not to report their unemployment to the authorities and hence were not counted. another and quantitatively more important reason for the small rise in unemployment was the large share of foreign workers with temporary work permits that obligated them to exit switzerland when they lost their jobs. around % of job losses were absorbed in this way . the proportion of foreigners with permanent residence permits has greatly increased since then, however, so that job losses today have a much greater impact on unemployment statistics than in the past. following the second oil price shock in the s, the unemployment rate then did exceed %, and this, as fig. shows, despite the fact that merely the growth in employment and not its level declined. this is undoubtedly a consequence of the introduction of universal fig. employment and unemployment in switzerland, annual averages, - . -great deflation, -great depression, - st oil price shock, - nd oil price shock, -double-dip recession, -dotcom bubble burst, -financial crisis. sources: unemployment: - : table f. a, swiss economic and social history online; - : federal statistical office. employment: - - office. notes: the unemployment rate measures the registered share of the labor force (= unemployed + employed) unemployed at a given time, i.e., unemployed/(unemployed + employed). in contrast to official statistics of registered unemployment, which update the denominator of the unemployment rate at irregular intervals, the unemployment rates in the chart below rest on ongoing employment figures. since employment in switzerland exhibited a trend increase over the period viewed here, the unemployment rates in the figure may at times lie below official figures unemployment insurance in , which requires registering at an employment office to draw benefits. the next major downturn came in the early s in the form of a double-dip recession. the first decline arose from a restrictive monetary policy aimed at combatting the high inflation stemming from an unintended monetary expansion resulting from the introduction of a new electronic interbank clearing system and from an overhaul of the liquidity requirements for swiss banks. the second contraction in / , on the other hand, followed from a misreading of the business cycle by the swiss national bank and a subsequent over-restrictive monetary policy. both shocks together caused the unemployment rate to rise to over . %, a level last recorded during the great depression. this sharp rise is undoubtedly due in part to increased unemployment insurance coverage and the more sedentary foreign labor force. the final two slowdowns came on the heels of the bursting of the dotcom bubble in the early s and the global financial crisis in / , respectively. the reaction of employment to both downturns was rather subdued compared to the size of the changes in gdp, however. econometric studies indeed confirm that the strength of the okun relationship linking unemployment to the size and sign of the output gap has been steadily decreasing since . the reason is not yet clear but it may be due to the trend decline in production jobs that typically react more strongly to business cycle fluctuations. compared to the past, an unemployment rate of . %, which the state secretariat for economic affairs is expecting for , thus does not seem that high or unique. yet, as already mentioned, the limitations of the data presented in fig. are also to be taken into account. the unemployment data are of dubious quality prior to the introduction of mandatory unemployment insurance in april . moreover, annual employment data for the period before do not even exist. to calculate the unemployment rate, defined as the share of unemployed in the labor force, or the sum of employed and unemployed, for the period before , one has to rely on the national censuses from , , , and , leaving large gaps for the intervening years. to make matters worse, the census employment data from those years exhibit a positive trend making it impossible to ascertain how many jobs were actually lost in the wake of the great deflation in the s or during the great depression in the s. the discussion above focused solely on the stock of unemployed and ignored the flows underlying stock changes. this is due to data availability. it was not until that the swiss unemployment registration system was digitalized making it possible to study the separate contributions of layoffs and hires to changes in the stock of unemployed. such knowledge is indispensable for forging effective labor market policy since most labor market measures are directed at flows. for example, short-time work attempts to stem inflows into unemployment while training measures aim to foster outflows into employment. two variables stand at the forefront of a stock-flow analysis of unemployment: the risk and the duration of unemployment. the risk of unemployment gives the probability that a member of the active labor force becomes unemployed in a given time interval and is calculated as the number of new entries into the stock of unemployed divided by the size of the labor force. the unemployment risk pertains to the incidence of unemployment. the duration of unemployment, on the other hand, measures the average length of a spell of unemployment, expressed in the same time units as the interval to which the risk of unemployment refers. measures of duration can apply to three types of unemployment spells: ongoing spells, beginning spells, and ending spells. the average duration of ongoing spells is probably the most widespread measure since its measurement only requires survey or cross-sectional data, which are commonly available. it has its shortcomings, however. for one, it only records the elapsed duration of unemployment at the time of the survey and hence is truncated. to measure the entire length of completed spells of unemployment requires panel data, which prior to the digitalization of unemployment registrations in were not regularly available in regard to unemployment in switzerland. the average elapsed duration of ongoing spells is not only subject to a truncation bias but to a sampling bias as well. the sampling bias stems from the fact that surveys sample from the stock of unemployed, which contains a greater share of long-term unemployment spells than found in the flows of beginning and ending spells. which bias dominates empirically depends on the shape of the unemployment hazard function, which gives an individual's probability of exiting unemployment as a function of the elapsed time already spent in that state. a decreasing hazard function means that the chances of escaping unemployment in the near future decline with the elapsed duration of unemployment. this is termed negative duration dependence and can result from scarring and/or unobserved heterogeneity among the unemployed . if the hazard function is decreasing, the average duration of ongoing spells will exceed the average duration of completed spells despite being based on truncated spells . this happens to be the case in switzerland . completed spells, on the other hand, can take two forms. they can pertain either to the spells ending or to those beginning in a particular time interval. the average duration of ending spells depends on the job opportunities that prevailed during the course of the spells it covers and thus is backward looking. as a consequence, the average duration of completed spells is typically higher in summer than in winter as numerous spells ending in summer begin in winter when job openings are rarer. in the following, we focus on the duration of beginning spells of unemployment because it captures current instead of past job opportunities and thus better lends itself to the study of the evolution of job opportunities over time. however, unlike the other two duration measures, the duration of beginning spells cannot be observed directly but instead has to be calculated using probability theory and hazard rates. a hazard rate h(t) gives the probability that a jobless individual will exit unemployment after t periods of being unemployed. in turn, the difference [ − h(t)], termed a survival rate, constitutes the probability of remaining unemployed in the same interval. in the following, we treat time as discrete and measure it in calendar months. under the assumption of stochastically independent hazard rates , the following product equals the probability that an unemployment spell is still ongoing k months after its start. since a time interval has a length of month, ( ) also gives the expected length of time, measured in fractions of a month, that an unemployed person will spend in the kth month of unemployment. s(.) is known as the survivor function, and s(k) gives the value of the function in the kth month. since ( ) equals the expected time that an unemployed person will spend in the kth month of unemployment, summing ( ) across all t + duration intervals of length one, where t equals the longest spell length, yields the total expected time that the person will spend in unemployment or, equivalently, the expected duration of beginning spells : as ( ) indicates, the expected duration is equal to the area below the associated survivor curve. in demographic terms, ( ) is equivalent to the life expectancy at birth, where the hazard rates represent age-specific mortality rates. in turn, the average duration of ongoing unemployment spells corresponds to the average age of the living, and the average duration of ending spells to the average age of the deceased. our procedure consists in calculating ( ) for every calendar month using the observed monthly exit rates of the registered unemployed subdivided by elapsed duration as hazard rate estimates. note that exits do not necessarily imply entering employment. this has important policy implications but has no bearing on the size of registered unemployment, which is the focus here. as the estimated hazard rates used to calculate the expected duration of unemployment apply to a single calendar month, the ensuing duration measure reflects solely the job opportunities prevailing in the given month. this enables us to assign a spell duration to a single calendar month. this is both unique and of great practical use. it is unique because the average duration of unemployment is typically longer than a month and thus not attributable to an individual calendar month, and it is of great practical use because it enables the construction of a time series describing the evolution of job opportunities from month to month. figure presents the seasonally adjusted monthly time series of the expected duration of beginning spells of unemployment for the months from january to june see salant ( ) . cf. https://wwz.unibas.ch/de/fruehindikatoren/ the mathematical theory of absorbing markov chains developed by kemeny and snell ( ) forms the basis of our approach. stone ( stone ( , stone ( , introduced markov chains into economic literature. sheldon ( ) first applied the concept to swiss unemployment data. sider ( ) and more recently shimer ( ) have applied a similar approach to data from the us current population survey (cps). their method is less straightforward, however, due to the survey quality of the cps data. stochastic independence is a fundamental assumption of markov chains. note that h( ) = and h(t) = . we set t to as very few unemployment spells in switzerland last longer than years. registered unemployed are defined in switzerland as jobless aged - who are registered at an employment office on the last day of the month and are immediately available for work. registered jobless who are not immediately available on the last day due, say, to participation in an active labor market policy (almp) program such as re-training are not counted as registered unemployed. they typically make up roughly a fifth of all people registered at an employment office. counting them as unemployed would raise the unemployment rate by one percentage point on average. another % of the registered consist of individuals who are not immediately available for work due, say, to illness, who are still within the notice period, or who are working yet receiving an insurance benefit such as reimbursement for commuting costs. the remaining % consist of registered unemployed. ( ) : page of based on ( ) along with the complementary series for the unemployment risk . as a comparison with fig. indicates, the period covered in fig. includes three past employment downturns (the double-dip recession in the s, the bursting of the dotcom bubble after and the financial crisis in / ) as well as the current downswing caused by the lockdown in march . a number of things stand out in fig. . for one, the chart reveals that the largest increases in both the risk and duration of unemployment occurred during the double-dip recession in the early s. switzerland has not experienced such large increases since. for another, it shows that the incidence and the duration of unemployment move roughly in unison across the business cycle suggesting that labor shedding and hiring freezes contribute approximately equally to cyclical upswings in unemployment. unique to the current crisis is the sharp upsurge in both the incidence and duration of unemployment. never before have the two variables risen so quickly in such a short time span. this undoubtedly stems from the suddenness and the universality of the lockdown. also striking is the rise in unemployment risk to a record level, especially in light of the widespread use of short-time work. duration has not yet risen to record heights but may if the downturn persists. a major unknown at the moment is how the economy will fare in the coming months. official statistics do not appear to provide much help in this regard. for example, preliminary estimates of gdp for the first quarter of , which, experience shows, are thereafter subject to significant revisions, did not become available until early june and will not be accessible for the second quarter until early september, hardly in time to provide reliable guidance to economic policy. in light of this, various researchers in switzerland have begun searching for more up-to-date indicators of economic activity. some have turned to transaction indicators such as credit card use or traveled miles, while others have focused on words searched in google such as "unemployment" or "vacancies". the time path of these indicators can give interesting insights into the general direction in which the economy is heading, but are not easily translated in terms of such major economic variables of interest as gdp or unemployment. in the following, we present two leading indicators that avoid these shortcomings. they are timely, fig. risk and duration of unemployment, seasonally adjusted, january -june . notes: the risk of unemployment measures the probability of becoming registered unemployed in a given calendar month and equals the number of individuals entering registered unemployment in that month divided by the current size of the labor force according to official registered unemployment statistics. the duration of unemployment gives the number of months that cohorts entering registered unemployment can expect to remain in this state and corresponds to the area under the survivor curve of the corresponding month calculated using eq ( ) and the computerized database underlying the official registered unemployment statistics including participants in an almp program raises duration by months and lowers risk by . percentage points on average, the latter due to the fact that some entries into registered unemployment represent returning participants from almp programs that are excluded when almp participants are counted as registered unemployed. ( ) : page of calculated monthly on the basis of the latest unemployment data that, unlike gdp estimates, are not subject to multiple revisions. in addition, the indicators are directly interpretable, have a good forecast record, and have been freely available to the public for over a decade. our indicators forecast the future values of (i) the unemployment rate and (ii) the share of long-term unemployed. the forecasts represent the values these variables would assume were the risk and expected duration of unemployment prevailing in a given calendar month to remain unchanged in the future. in other words, they correspond to the unemployment rate and the share of long-term unemployed that the risk and duration of unemployment prevailing in a given calendar month imply stochastically in a steady state, i.e., in the longer term. equation ( ) serves as our point of departure in deriving the leading indicator for the unemployment rate. since ( ) gives the probability that an unemployment spell is still ongoing k months after its start, multiplying it with the size n of entering cohorts, as shown in ( ), yields the expected number of individuals in the associated duration classes in steady state. repeating the calculation in ( ) for all t + duration months or values of k and summing the results therefore yield the expected number of unemployed u that the size of entering cohorts and the expected unemployment duration prevailing in a given calendar month imply long term, i.e., dividing both sides of ( ) by the size lf of the labor force thus produces the corresponding unemployment rate u%: hence, by multiplying the two series in fig. , one obtains a time series giving the expected future time path of the unemployment rate that the risk and the expected unemployment duration prevailing in the various months imply. note that ( ), unlike most leading indicators, does not rest on an empirical regularity but, instead, on a mathematical law. hence, a calculated expected unemployment rate would necessarily coincide exactly with the observed average long-term rate if the underlying unemployment risk and duration were to remain unchanged. as the latter is not to be expected, we update the indicator every month employing the latest data from the electronic unemployment registration system of the state secretariat for economic affairs. this yields a rolling forecast of the future unemployment rate at monthly intervals. a central issue at this juncture is the forecast accuracy of our indicator. figure provides a visual answer. as the chart shows, the relationship between the predicted ("expected rate") and the observed unemployment rate ("current rate") is much like that between marginal and average values. when our indicator (the marginal value) lies below the observed rate, the latter (the average value) falls, and when it lies above it, the latter rises. this finding implies that our leading indicator is a driving force underlying the time path of observed unemployment. the acid test for any leading indicator is whether it succeeds in predicting the turning points in the series to which it pertains. figure suggests that that is the case in regard to our indicator. in fact, our indicator was the only one that in the fall of correctly predicted the trend reversal of the unemployment rate in . at the time, all forecasts predicted the unemployment rate, which stood just above % in late , to exceed % in the coming year. in reality, it fell below %. to determine the average lead time of our indicator, we search for the lagged value of the indicator that maximizes r squared in a regression of the observed unemployment rate on a single lagged value of the indicator. we find that r squared reaches its maximum of % at a lag length or lead time of months. in fig. , the lead time corresponds to the horizontal distance between the two curves. see https://wwz.unibas.ch/de/fruehindikatoren/ . if hazard rates h(t) do not vary with elapsed time t, ( ) reduces to / h, or /( −s) in terms of the complementary uniform survivor rate s. the similarity to the keynesian income multiplier is not just coincidental since both represent the sum of an infinite decreasing geometric series. moreover, the similarity points out the fact that the expected spell duration acts like a multiplier in translating the flow n of new unemployment spells into the stock u of unemployed. the longer the duration, the larger is the stock of unemployed that a given cohort size produces. in the matrix notation of markov chains, the reciprocal /( −s) corresponds to the inverse matrix [i−s] − , which is known as the fundamental matrix of a markov chain and in inputoutput analysis as the leontief inverse, where input coefficients replace the survival rates s(t) represented by s in the inverse matrix. the mathematics are the same, however, which is why contributions by stone ( stone ( , often appear in works on input-output analysis. cf. sheldon ( ) . sheldon swiss journal of economics and statistics ( ) : page of what does our indicator portend now for the near future? the curves in fig. imply that, based on the risk and expected duration of unemployment prevailing in june , the seasonally adjusted unemployment rate of . % at the end of june will exceed % in months, a level that the indicator last reached in the early s. note, though, that our indicator tends to overshoot the peaks in the published unemployment series by . to . percentage points. this is probably due to the fact that layoffs are usually quick and widespread, whereas recoveries are typically gradual and uneven. consequently, the risk and expected unemployment duration vary asymmetrically across the cycle, increasing rapidly and strongly in a downturn, causing our indicator to rise sharply, and decreasing more gradually in an upswing, causing our indicator to decline slowly. hence, our indicator may be providing an overly pessimistic forecast at the moment. based on the experience of the s, a forecast of % is probably more accurate. on the other hand, though, the indicator gives no indication of an approaching turnaround. to derive our second leading indicator, the expected share l of long-term unemployed that current cohort sizes and expected unemployment durations imply for the future, note that the share of long-term unemployed is defined in switzerland as the number of jobless that have been unemployed for at least months divided by the total number of unemployed. hence, based on ( ), the expected share of long-term unemployed implied by the cohort size and expected duration of unemployment prevailing in a given calendar month equals which is equivalent to the ratio of the area below the survivor curve above months to the total area under the curve. as ( ) indicates, the size of entering cohorts has no bearing on the value of the share of long-term unemployed. it depends solely on the slope of the survivor curve or the underlying hazard rates. moreover, since it is essentially arbitrary where one draws the line between short and long-term unemployment, ( ) implies more generally that the size of entering cohorts has no impact on the distribution of elapsed spell lengths in the steady-state stock of unemployed. figure compares the time path of our leading indicator for the share of long-term unemployed ("expected share") to that of the observed value ("current share"). as the chart indicates, our indicator exhibits a lead time of just over a year as one would expect given the definition of long-term unemployment. regressions of the observed values of the share of long-term unemployed on varying lagged values of our leading indicator indicate that r-squared reaches its maximum of % at a forecast in light of its long forecast horizon, it is astonishing to observe in fig. how well the indicator predicts turning points in the observed share. we know of no other leading indicator that has this kind of forecast ability. apparently, the die is cast so early in the unemployment process that the subsequent level of economic activity or policy interventions fails to have an impact on the share of long-term unemployed. given this degree of persistence, fig. implies that the proportion of long-term unemployed, currently standing at %, will increase to the record level of over % in months , and this although the share of long-term unemployed is currently falling. however, the latter is merely a result of the current strong influx of new unemployment spells of short elapsed duration, which increases the denominator of the long-term unemployment share while leaving the numerator unchanged. a large share of long-term unemployed is problematical. it tends to slow recovery because long-term unemployed, as declining hazard rates indicate, have greater difficulty finding jobs, be it that persistent unemployment signals serious deficiencies to potential employers, or be it that continuing unemployment destroys job skills. this can result in cyclical unemployment mutating into structural unemployment placing a large drag on recovery. our discussion has shown that unemployment rates in excess of %, which the state secretariat for economic affairs predicts for , are historically not without precedent in switzerland. available statistics show that the unemployment rate rose above that level during the great depression in the s and even as recently as in the early s during the double-dip recession. it is questionable, however, whether figures for registered unemployment collected prior to the introduction of mandatory unemployment insurance coverage in april lend themselves to comparison with today's figures. before the introduction of mandatory insurance, a large majority of the labor force (roughly % shortly before april ) was not insured against unemployment and, without claims to insurance benefits, probably did not report their unemployment to the authorities. furthermore, the majority of foreign workers in switzerland prior to the s only held temporary work permits and had to exit switzerland when they lost their jobs, further lowering the unemployment rate. a decomposition of the unemployment rate into its flow components, unemployment incidence and duration, made possible by the digitalization of the federal unemployment registration system in , indicates that increases in the two flow variables have contributed roughly equally to the sharp rise of the unemployment rate following the pandemic-induced lockdown in march. this has seen unemployment risk rise to a record height despite the fact that roughly a quarter of the labor force went on short-time fig. current and expected share of long-term unemployed, january -june , seasonally adjusted. notes: the expected share of longterm unemployed in a given month equals the ratio of the area under the survivor curve of that month above the -month mark divided by the entire area underneath the same curve according to eq ( ) work to avoid unemployment. the average duration of unemployment spells, on the other hand, remains just below its record length set during the double-dip recession in the early s. our leading indicators for the unemployment rate and the share of long-term unemployed, which have yielded comparatively accurate forecasts in the past, point to a worsening labor market situation in the coming months. based on current indicator values, we can expect the seasonally adjusted unemployment rate to climb from . % at the end of june to roughly % in the next months, and the proportion of long-term unemployed to rise from % currently to over % in the next months. the forecast for the unemployment rate equals the previous record set in the early s, while the forecast for long-term unemployment represents a new high mark. the strong increase in long-term unemployment is particularly worrisome as long-term unemployed are hard to place and hence put a drag on recovery. in looking to the future, we expect labor shedding to taper off as the lockdown is eased and the duration of unemployment spells to lengthen as businesses enact hiring freezes in an attempt to climb out from under the mountain of debt they accumulated in lieu of vat refunds to survive the lockdown. lengthening unemployment spells will increase long-term unemployment for sure, but the effect of reduced incidence and increased duration on the unemployment rate is uncertain as the two forces counteract each other. the future will have to show which of the two effects proves to be decisive. abbreviations almp: active labor market policy; cf.: confer/conferatur; gdp: gross domestic product; oecd: organisation for economic co-operation and development; wwi: world war i; wwii: world war ii swiss monetary history since the early th century bestimmungsfaktoren der entwicklung der arbeitslosigkeit in der schweiz im zeitraum - . study commissioned by the the state secretariat for economic affairs does unemployment cause future unemployment? definitions, questions, and answers from a continuous time model of heterogeneity and state dependence finite markov chains niveau und struktur der arbeitslosigkeit in der schweiz. geld, währung und konjunktur, . swiss national bank search theory and duration data: a theory of sorts unemployment and unemployment insurance in switzerland wende auf dem schweizer arbeitsmarkt in sicht reassessing the ins and outs of unemployment unemployment duration and incidence demographic input-output: an extension of social accounting the fundamental matrix of the active sequence a system of social matrices publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations the author acknowledges helpful comments from an anonymous referee and the editor. author's contributions all contributions are attributable to the author. the author read and approved the final manuscript. none. the data presented in the paper were generated by the author from raw data drawn from the electronic unemployment registration system of the state secretariat for economic affairs in berne, switzerland. the raw data are available under permission from the state secretariat for economic affairs. none.received: june accepted: july key: cord- -kamvao b authors: o'brien, john d; she, zhen-su; suchard, marc a title: dating the time of viral subtype divergence date: - - journal: bmc evol biol doi: . / - - - sha: doc_id: cord_uid: kamvao b precise dating of viral subtype divergence enables researchers to correlate divergence with geographic and demographic occurrences. when historical data are absent (that is, the overwhelming majority), viral sequence sampling on a time scale commensurate with the rate of substitution permits the inference of the times of subtype divergence. currently, researchers use two strategies to approach this task, both requiring strong conditions on the molecular clock assumption of substitution rate. as the underlying structure of the substitution rate process at the time of subtype divergence is not understood and likely highly variable, we present a simple method that estimates rates of substitution, and from there, times of divergence, without use of an assumed molecular clock. we accomplish this by blending estimates of the substitution rate for triplets of dated sequences where each sequence draws from a distinct viral subtype, providing a zeroth-order approximation for the rate between subtypes. as an example, we calculate the time of divergence for three genes among influenza subtypes a-h n and b using subtype c as an outgroup. we show a time of divergence approximately years ago, substantially more recent than previous estimates which range from to years ago. precise estimates are sorely lacking for dating the emergence and divergence of viral subtypes. improved estimates equip epidemiologists and virologists to begin to correlate these important establishing events with historical demographic changes, geographical invasions and zoonoses, the transferring of a virus from one host species to another [ , , ] . for example, archeological sequence data can furnish accurate dates and show that substantial genomic changes associate with geographical invasion and zoonosis [ , ] . further, the recent availability of viral gene sequences sampled at a pace commensurate with their rate of nucleotide substitution vastly augments the ability to rigorously infer the time scale of phylogenies and hence determine the time of the most recent common ancestor (tmrca) for different viral types [ , , ] . systematic studies characterize the substitution process and substitution rate process of several classes of viral subtypes in, for example, dengue, influenza subtype a, human immunodeficiency virus (hiv) and the virus responsible for sudden acute respiratory syndrome (sars). for the last three viruses, a unique zoonotic transfer appears to co-occur with substantial changes in both the composition of nucleotides and amino acids as well as alterations in the rate of nucleotide substitution [ , , ] . in dengue, where a single subtype simultaneously inhabits two hosts (humans and aedes aegypti) in a persistent zoonotic process, the introduction of the virus to new geographical environments associates with a dramatic increase in sequence diversity [ ] . unfortunately, no studies thus far analyze the rate of nucleotide substitution during either geographical invasion or zoonosis. consequently, studies of the date of origins of viral subtypes must use strong a priori assumptions on the rate structure of nucleotide substitution. two primary methods find use to date the time of viral subtype divergence. the most commonly employed approach determines the divergence time of subtypes using a molecular clock assumption (mca) over an entire phylogeny [ , , , ] . in its strict formulation, the mca posits a proportional relation between the number of substitutions and the intervening time period over the entire phylogeny. looser forms of mcas require only that the proportionality hold along individual branches, with the rates across branches drawn from a pre-specified distribution [ ] . committed to some variant of the mca, current algorithms then estimate the rate of nucleotide substitution over all taxa in a given set. consequently, these methods provide inference most suitable for situations where sequence evolution follows a mca (e.g. influenza a-h n in human hosts, as in [ ] ) or deviates from the mca homogenously in time (e.g. perhaps influenza a in wild fowl, see [ ] ). in considering divergence events between viral subtypes, even when the mca well-approximates nucleotide substitution within a given subtype, the above methods may incorrectly infer the time of divergence across subtypes. by either assuming that a single rate of nucleotide substitution holds for the region preceding the common ancestor of each subtype or by smoothing the rate of nucleotide substitution over clades with different numbers of taxa, the adherence to a mca prevents direct inference of the rate during subtype divergence. suzuki and nei ( ) propose an alternative, more heuristic method of estimation to counteract the problem of differing rates of substitution before and after zoonotic events [ , ] . in these studies, the evolutionary models draw a distinction between the rate of substitution within a given subtype and the rate of substitution between subtypes. however, trouble arises since there are no methods for estimating the latter quantity. consequently, the models assume that the rate of substitution for portions of the phylogeny between the subtypes equals the mean rate in the initial host species population. for instance, in dating the time of divergence between influenza b hemagglutinin and influenza c hemagglutinin-esterase, suzuki and nei use the rate of amino acid substitution for water fowl for the portions of the phylogeny previous to the tmrca of these two proteins [ ] . while this method may accurately reflect the rate within avian and human hosts, it neglects whatever additional changes in the rate of substitution are due to the process of zoonotic adaptation, likely leading to a substantial underestimation of the date of the tmrca. the study here focuses on influenza, although the techniques are readily applied to other rapidly evolving organisms. influenza has three types, a, b and c, classified based on serological analysis. to date, only type a sequences have been demonstrably associated with global pandemics [ ] . since modern surveillance began in the s, type b has only been responsible for mild epidemics while type c has been nearly asymptomatic in human infection. several subtypes of a, notably h n and h n , are currently co-circulating in the human population. as the h n and h n subtypes may be as divergent from each other as they are from types b and c, we will refer to all types and subtypes simply as subtypes for the remainder of this paper. we select for this study three genes, coding for hemagglutinin (ha), the matrix protein (mp) and the non-structural protein (ns) responsible for interfering with host immune response. subtype c has a hemagglutinin-esterase gene that is analogous to the hemagglutin gene in other subtypes [ ] . we hence refer to the hemagglutinin gene generally and the hemagglutininesterase gene when referring specifically to the subtype c sequences. we present a simple estimation tool to determine the date of divergence among viral subtypes that overcomes the difficulties encountered with use of the mca by measuring the pairwise rate of substitution between taxa. our estimator derives from the triplet statistic developed in [ , , ] , where each sequence member of the triplet draws from a different subtype. in this manner, we generate from each triplet an estimate of the rate of nucleotide substitution between the most recently diverged subtypes, and consequently provide an estimate of the tmrca. this circumvents the problems posed by earlier methods by directly estimating the pairwise rate of nucleotide substitution over the set of pairs of sequences straddling the subtype divergence without any further rate assumptions other than the existence of a mean. however, this method is only capable of determining the rate between two subtypes where a third, more distantly related, subtype functions as an outgroup. this method thus trades the ad hoc rate assumptions of the previous methods with two implicit conditions: (i) that subtypes have a unique divergence and (ii) a third, comparable subtype is available to serve as an outgroup. in exchange, we arrive at a precise statistical measure of the tmrca that converges as the number of taxa increases and is robust to the balancing of the numbers of taxa between different subtypes. we show that applying this method to dating the divergence of influenza subtypes a-h n and b gives a time of diver-gence approximately years before present, substantially more recent than previous estimates. to calculate the rate of nucleotide substitution, we require a measurement of the number of nucleotide substitutions occurring in a given time interval. starting from a given set of aligned sequences {s , ..., s n } for n taxa, we define the pairwise distance in number of substitutions to be the estimates {k ij } under a given model of nucleotide substitution. naturally the unobservable true values {d ij } of the pairwise distances differ from their estimates {k ij }. to understand this difference, we associate each d ij with an error ε ij and assume that ε ij tends to zero as sequence lengths increase without bound. we further assume that the covariance between errors, cov(ε ij ; ε mn ), is bounded and known. for time measurements, we assume that each sequence is labeled by a sampling time t i given in consistent units. since we know only the sampling time of a given sample up to the unit of time reported (day, month, year) we posit an uniform error ν i ~ u [ , ] underlying each t i over the unit sampling interval. to complete the error structure specification we force the two forms of error (ν i and ε ij ) to be independent. finally, for a set of three sequences (s i , s j , s k ) and their associated pairwise distances, we enforce a fixed topology among sequences, as shown in figure , via methods outlined in [ ] . we augment the topology with the observed sampling times of the three sequences, α, the divergence time between the two sequences of interest and β, the divergence time of all sequences. when necessary for clarity, we write α ij to indicate the true time of divergence between sequences i and j. under our triplet method, we aim to estimate the true rate of nucleotide substitution, p ij , between sequences s i and s j with an unobserved error δ ij . with respect to outgroup sequence k, an unbiased estimate is where the factor corrects for bias resulting from the time sampling error structure (see appendix for derivation). we superscript to denote its weak dependence on outgroup sequence k. dependence is weak as the path of evolution from t k to α is shared between the paths from sequence k to both sequence i and sequence j and hence largely cancels out in equation . we make this transparent in the following derivation. for brevity, we consider only unobservable true values, ignoring error terms. let u be the location on the triplet in figure corresponding to time α and let p xy be the true rate along the path connecting locations x and y. then, as distance is rate multiplied by time, we have subtracting the first equation from the second equation , which is equivalent to equation . this derivation makes clear that the estimator ( ) measures the rate along the path from sequence i to sequence j, with only incidental dependence on sequence k. the variance for the estimator ( ) is well approximated by further, we can estimate the time of subtype divergence α ( figure ) between sequences via we note that the term t i + t j - is used rather than t i + t j to account for the expected error coming from the uniformly the phylogenetic relationships between three sequences s i , s j and s k , sampled on dates t i , t j and t k respectively as nucleotide data increases without bound, k ij → d ij and → p ij , ensuring that → α ij . for finite sequence lengths, this relation ensures that . to gain an understanding of this estimator, we note that with a standard model of substitution (e.g. jc , hky ), a rate of substitution of - (s/s/yr) and a sequence of nucleotides, the above estimator yields a standard error of approximately years [ ] . the above derivations express our rate and time estimates for a single triplet of sequences. we now consider estimates that combine information across multiple representative sequences from each subtype. for discussion, we label subtypes a, b and c (which are only incidentally the same as the labels for influenza) and we assume the topology in figure for these groups. we let n r , where r ∈ {a, where p α is the sum of the inverse variance of each estimate, . having found , we estimate its variance by a bootstrap resampling of sequences from each subtype [ ] . the computational efficiency of this estimator is on the order o(n ) for a tree of n taxa. this is natural as each of the initial rate estimates is composed of information concerning three taxa. while the growth of computational expense in the number of taxa may appear unpleasant, in practice this algorithm is both fast and stable, owing to the absence of costly optimization procedures for parameter inference, and is able to handle data sets of thousands of taxa. the authors detail the computational efficiency of a similar statistic in [ ]. as an example, for the data presented below all computations required only a few seconds on a desktop computer. we demonstrate the advantage of our triplet estimator through analysis of influenza a-h n /b subtype divergence using the hemagglutinin (ha), matrix protein (mp) and non-structural (ns) genes. each analysis is performed on gene sequences constructed from genomes each drawn from influenza subtypes a-h n , b and c. we download these data along with their dates of sampling from the los alamos influenza database [ ] . we perform sequence alignment using clustalx [ , version . ]. for consistency with previous studies of a-h n ha evolution, we use the hky model of nucleotide substitution [ ] . we use the treble algorithm, which implements a mca, on sets of sequences solely drawn from a single subtype to derive within-subtype rates. the phylogenetic tree, generated by treble, for the ha gene is depicted in figure (± . ) × - s/s/yr and the subtype c rate is . (± . ) × - s/s/yr. lastly, for the ns gene, the rates are similar to those of the mp gene. the subtype a-h n rate is . (± . ) × - s/s/yr, the subtype b rate is . (± . ) × - s/s/yr, and the subtype c rate is . (± . ) × - s/s/yr. table presents these results. figure provides histograms of the bootstrap distributions for all three genes and subtypes. assuming a molecular clock within a subtype and with the rates above, we generated the corresponding dates of the tmcra. figure shows histograms of the tmrca estimates for different genes and subtypes. all genes are similar in dating the tmrca for a-h n to approximately ( , , and for ha, mp and ns genes, respectively). these dates are consistent with the emergence of the a-h n subtype into global circulation dur-ing the pandemic [ ] . both the mp and ns genes date the tmrca of subtype b to , while the ha rate places the tmrca at . this latter value is inconsistent with the influenza b sub-epidemics of - but is consistent with the emergence of the more lethal victoria strain of influenza b in [ ] . each of these estimates has a standard error of approximately years and so these discrepancies may be accounted by measurement uncertainty. the year gap between the tmcra suggested by the different genes can be explained by a reassortment event. finally, the tmrca of subtype c is calculated as and by the mp and ns genes, respectively, while the ha gene places the tmcra at . this nearly half century discrepancy suggests that the subtype c ha gene experienced a markedly different evolutionary history than either the mp or the ns gene. a biologically plausible explanation would be a reassortment event. another possible explanation is that non-mca rate behavior has lead to substantial bias in dating the tmrca. we now compare the results from pairwise rate estimates across subtypes a-h n and b with those from application of the mca to the same data. these results are summarized in table and histograms of the time of most recent common ancestor for subtypes a-h n , b and c, respectively, derived from molecular clock estimates on hemagglutinin (ha), matrix (mp) and nonstructural (ns) gene sequences this discrepancy between the two sets of estimates of the tmrca likely owes to the inability of the mca to integrate information from the period of evolution between the two subtypes, leading to a substantial underestimate of the rate of substitution, and consequent underestimation of the date of the tmrca. we present a new method for ascertaining the rate of nucleotide substitution between subtypes and apply this method together with traditional mca methods to date the divergence of influenza subtypes a-h n , b, and c. we use three genes, ha, mp and ns, to date two types of divergence events: the time of the most recent common of each subtype and the time of divergence between two subtypes, a-h n and b. for the former event type, we show that the three genes are loosely consistent in their dating of the tmrca of the subtypes, with the notable exception of the ha-derived estimate of subtype c's tmrca approximately years before the mp-and ns-derived estimates. this discrepancy may indicate either that subtype c's hemagglutinin-esterase gene engaged in a biologically significant event, such as reassortment, or that mca estimation does not adequately model the evolution of the gene. for the divergence between subtypes a-h n and b, previous studies using the mca generally place a time of divergence of several hundred years ago, ranging from the th to early th centuries. other analysis have yielded estimates of years ago [ ] . in the current study, application of the mca yielded estimates in the last half of the th century. however, applying the pairwise rate estimate developed above we find uniformly, across genes, that the divergence likely occurred in the very early th century. the discrepancy between these two measures is likely due to the increased modeling flexibility of the pairwise rate estimate relative to the mca. this discrepancy between the rates and corresponding tmcra estimates has important biological consequence. the phylogenetic divergence between subtype a-h n and b corresponds to a subspeciation event for the virus. the results in this study indicate that the process of speciation is not neutral but instead a period of rapid and intense genetic change. the three genes studied here consistently show large acceleration in the rate of nucleotide substitution for the divergence period relative to the rates observed within a stable subtype. this study gives strong evidence that, at least for influenza viral subtype divergence, the process of subspeciation is associated not just with large genomic changes but also with an accelerated, finite process of adaption. histograms of the time of most recent common ancestor of subtypes a-h n and b, derived from molecular clock estimates (light grey) and pairwise estimates (dark grey) on hemagglutinin (ha), matrix (mp) and nonstructural (ns) gene sequences assuming that the more recent estimate is correct, a subsequent question is whether or not a pandemic or epidemic associates with subtype a-h n /b divergence. in the twentieth century, all influenza pandemics associate with the emergence or reemergence of subtypes (a-h n in , a-h n in and a-h n in ). serological analysis indicates that the pandemic was likely due to subtype a-h n . however, the pandemic of is of uncertain type, although it is commonly reported in the literature as being due to a-h n [ ] . the above analysis suggests that it is possible to postulate that the cause of this pandemic is due to the emergence of subtype a-h n or b. as noted above, we condition the results presented here on a specific sequence alignment. as the question under consideration concerns the divergence of specific genes and proteins over a (presumably) long time scale, the capacity to generate reasonable alignments diminishes with increasing time of divergence between types, conditional on the rate of substitution. we find that for the hemagglutinin gene, a proportion of sequence alignments support the split of subtype b from subtype c after the split between subtypes a-h n and b, in opposition to the topology enforced in our analysis. hence, to some unknown degree, our analysis is necessarily biased by the choice of alignment. this suggests that improved dating can be found by integrating estimation procedures over an ensemble of alignments [ ] . the pairwise estimate method presented above is accurate in the scale where is the total time over the phylogeny and p is mean rate over the phylogeny [ ] . this relation dictates that as divergence events become more remote the ability of the triplet method to resolve the time of divergence diminishes. while this limit prohibits the calculation of remote divergence events, the example presented above lies within the appropriate scale. in place of a specific mca, the estimates presented here directly calculate the rate of substitutions between taxa from different viral subtypes. as such estimates span paths between subtypes, they simultaneously capture the rate evolution along branches both within and between subtypes. from these estimates, we are able to directly infer the time of divergence between subtypes. as a trade-off for limited mcas, the method requires an outgroup subtype to function as an origin relative to the subtypes under consideration. we feel that the triplet method provides a simple and widely applicable way to calculate the dates of divergence of rapidly evolving organisms without the pitfalls of the mca. we present a simple method for calculating the time of viral subtype divergence that does not assume a molecular clock over the entire phylogeny. additionally, the estimator of this method, a weighted sum of pairwise estimates, furnishes a defined variance for the time of the most common ancestor between subtypes. as a tradeoff for this increased precision, the structure of the triplet statistic requires an outgroup set of sequences, usually a closely related subtype. we apply this estimator to the case of influenza subtype divergence, considering three genes. we show that the estimated divergence time of subtypes a-h n and b is more than a century later than those calculated with a molecular clock. since we assume that the ν and ε structures are independent, the right side of the equation can be further reduced, yielding let Δt = t i -t j . the final expectation on the right hand side resolves by direct integration, we note that as the sampling time is independent of the rate of nucleotide substitution, the error increases in proportion to the magnitude of the initial statistic. we can then create a new, unbiased statistic by counterbalancing the original statistic with this factor, making a new statistic influenza virus genetics epidemiology of influenza c virus in man: multiple evolutionary lineages and low rate of change avian influenza virus exhibits rapid evolutionary dynamics influenza pandemic periodicity, virus recycling, and the art of risk assessment. emerging infectious diseases relaxed phylogenetics and dating with confidence estimating mutation parameters, population history and genealogy simultaneously from temporally spaced sequence data measurably evolving populations ecological and immunologial determinants of influenza evolution dating the human-ape splitting by a molecular clock of mitochondrial dna a twenty-one-year experience with anitgenic variation among influenza b viruses robust statistics: a review statistical estimation of parameters in a phylogenetic tree using a dynamics model of the substitutional process tracing the origin and history of the hiv- epidemic. proceeding of the national academy of sciences date of origin of the sars coronavirus strains the value of a database in surveillance and vaccine selection transmissibility of pandemic influenza estimating the rate of molecular evolution: incorporating non-contemporaneous sequences into maximum likelihood phylogenies joint bayesian estimation of alignment and phylogeny tests of applicability of several substitution models for dna sequence data r s: inferring absolute rates of molecular evolution and divergence times in the absence of a molecular clock a viral sampling design for testing the molecular clock and for estimating evolutionary rates and divergence times origin and evolution of influenza hemagglutinin genes the clustal x windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools inferring the rate and timescale of dengue virus evolution jdo'b collected the data, designed and performed the study and wrote the initial manuscript. zss provided extensive review of the study design and provided assistance in revising the manuscript. mas contributed extensive work in reviewing and revising the manuscript. initially, one might define an estimator of the conditional pairwise rate to be that has been previously used in the paper outlining the treble algorithm [ ] , and originates in [ ] . however, this apparently natural statistic is substantially biased when the sampling times of sequences i and j are close. to be seen in the following derivation, this bias is the result of the time sampling error structure.as the true value of the rate of substitution is given by we then have an expression for the error:taking the expectation yields the bias:publish with bio med central and every scientist can read your work free of charge ). key: cord- -g de fwj authors: kriegel, m.; buchholz, u.; gastmeier, p.; bischoff, p.; abdelgawad, i.; hartmann, a. title: predicted infection risk via aerosols date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: g de fwj currently, airborne transmission is seen as the most important transmission path for sars-cov- . in this investigation, models of other researchers with the aim to predict an infection risk for exposed persons in a room through aerosols emitted by an infectious case-patient were extended. as a novelty parameters or boundary conditions, namely the non-stationarity of aerosol and the half life of aerosolized virus, were included and a new method for determining the quanta emission rate based on measurements of the particle emission rate and respiratory rate at different types of activities was implemented. as a second step, the model was applied to twelve outbreaks to compare the predicted infection risk with the observed attack rate. to estimate a 'credible interval' of the predicted infection risk the quanta emission rate, the respiratory rate as well as the air volume flow were varied. in nine out of twelve outbreaks, the calculated predicted infection risk via aerosols was found to be in the range the attack rate (with the variation of the boundary conditions) and reasons for the observed larger divergence were discussed. the validation was considered successful and therefore, the use of the model could be recommended to predict the risk of an infection via aerosols in given situations. furthermore, appropriate preventive measures can be designed. the respiratory route is the main mode of transmission for the virus causing covid- (sars-cov- ) [ , , ] . the virus is transported on particles that can enter the respiratory tract. whereas larger particles (droplets) are only able to stay in the air for a short time and just in the near field (approx. . m), because they settle down quickly, smaller particles (called aerosols) are also concentrated in the near field and in addition can follow the air flow and cause infections in the far field. epidemiologically, short-range transmission (through aerosols or droplets) is distinguished from long-range transmission (aerosol) . in order to perform an infection risk assessment for the airborne transmission in the far field and to introduce appropriate preventive measures, it would be necessary to know the amount the so-called aerosols (liquid or solid particles in a dispersed phase with a fluid) as well as droplets differ by size. the particles, which are transported in a fluid over a longer distance, are called aerosols. droplets are stronger influenced by gravitation and are depositing more rapidly. depending on the fluid velocity the size of particles, which can be transported in air for a longer distance, is different. in internal spaces with typical air velocities of up to . m/s particles smaller than μm will be distributed by air very well, with a higher air velocity larger particles may be transported in air as well. sars-cov- was found to be transmitted via close contact as well as over distance in internal spaces, whereby in distant transmission so-called super-spreading events are more probable [ , , ] . in , riley et al. [ ] evaluated a measles outbreak in a suburban elementary school. based on the number of susceptible persons (s), which have been infected (d) during each stage of infection, the risk (p) for an infection in this stage has been calculated regarding equation ( ) . therefore, the risk for an infection has been defined as the percentage of infected persons from the number of pupils not already infected or vaccinated. ( ) a poisson-distribution of the risk of infection has been assumed as well as a stationary and evenly distributed concentration of the pathogens in the room air. equation ( ) shows the poisson-distribution. therefore, wells defined in [ ] a size called quantum as the number of emitted infectious units, where the probability to get infected is − − = . %. hence, a quantum can be seen as a combination of the amount of emitted aerosols with the virus transported on them and a critical dose, which may result in an infection in . % of the exposed persons. using the quantum concept as well as equation ( ) has been combined by riley [ ] to equation ( ) . in equation ( ), the number of infectious persons (i), the quanta emission rate depending on the activity (q), the pulmonary ventilation rate of exposed susceptible persons (qb), the duration of stay (t) and the volume flow of pathogen free air (q) was used. the quotient q/q represents the quanta concentration. in poorly ventilated rooms, the assumption of a stationary concentration of quanta is not justified, because of the long time, which is necessary until the stationary concentration is reached. the normalized time-dependent concentration process can be calculated according to equation ( ) and is shown in figure . how rapidly the concentration of a human emitted contamination in a room raises depends on the air exchange rate (ach) and the time (t). this relative concentration (crel) can be seen as an increase in the concentration compared to the volume flow. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . in all published studies identified ideal mixing ventilation was assumed, which means that aerosols are evenly distributed in the room air. to avoid this assumption noakes and sleigh [ ] divided the room air into different zones, which are themselves considered to be well mixed and have a uniform concentration. this should make it possible to calculate local differences in concentration and thus locally differing infection risks. furthermore, other studies, which focus on the unsteady conditions mostly use the boundary condition of a starting concentration of ( = ) = ³ . gammaitoni and nucci [ ] implemented the starting condition of ( = ) = as well as the number of exposed susceptible people, which may also change over time depending on their immune status. the equation ( ) . if r is known, q can be estimated as proposed by dai and zhao [ ] . for sars-cov- the average basic reproduction number has been estimated to be . [ ] , . [ ] and . [ ] . the virus can be transported on particles in air and the emission of aerosols can be used as an indicator for the emission of virus, but a correlation between q and the aerosol emission rate (e) has not been investigated so far. in measurements at the hermann-rietschel-institute (hri) of technical university of berlin [ , ] the particle emission rates during breathing, speaking, coughing as well as singing was measured. during breathing through the nose about particles/s was emitted and during coughing about , particles/cough, whereas it can be seen that depending on the activity a wide range of particle emission rates can be found. the transmission of a pathogen via aerosols is also influenced by the stability of the virus in the environment. in an experimental study van doremalen et al [ ] besides the number of emitted pathogen-laden aerosols, the number of inhaled pathogens is playing an important role as well with regard to the assessment of the risk of infection. the pulmonary ventilation rate may differ with different activities. gupta et al. [ ] performed a study with healthy adults and found a sine wave for mere breathing, but a more constant volume flow during talking. all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . in measurements with athletes as well as sedentary persons a maximum volume flow for the athletes of l/min ( m³/h) was found by córdova and latasa [ ] . to measure the airflow without movement restrictions, a helmet was used by jiang et al. [ ] for children, the lung volume is smaller. therefore, the respiratory rate for children aged can be assumed to be . m /h for low activity (breathing while sitting, standing, talking) [ ] . the wells-riley equation can be summarized as equation ( ). to calculate the predicted infection risk via aerosols (pira) in the far field of a room the concentration of quanta (c(t)) and the respiratory rate (qb) has to be known. the integration of c(t) can be understood as the amount of particles inhaled per m /h. with qb the number of inhaled quanta can therefore be calculated. all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . equation ( ) can be used for the definition of the quantum emission. this leads to a quanta emission rate of q = /h at an assumed mean r = . . the mathematical approximation presented by dai und zhao [ ] can be optimized by equation ( ), see figure . for figure the quanta emission rate has been correlated with r of tuberculosis [ , ] , influenza [ , ] , mers [ , ] and sars-cov [ , ] . equation ( ) all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint q is influenced by the activity of the person as was shown by buonanno et al. [ ] . therefore, the measured aerosol emission rates [ , ] were correlated with the calculated quanta emission rates influenced by the activity by equation ( ) . for low-activity (breathing, talking, sitting, standing) a basic volume flow qb,o and normal activity = low activity (breathing, talking, sitting, standing) with a basic emission rate of e was used. furthermore, the basic q (q ) was calculated with usage of r regarding equation ( ) . with these specifications qa can be calculated. , = . ℎ ; = [ ] the effect of e.g. mouth-nose protection can be considered by using their filtration efficiency (fmns) like in equation ( ) which however will not be further considered in the following. , = • it is known that the infectivity of an infected person depends on the disease progression over time [ ] . this is shown qualitatively in figure . with a simplified mathematical approach, this can be integrated into the quanta source rate. an equation could be implemented to take this into account. all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . the concentration of quanta during the increase ci(t) can be calculated according to equation ( ) with the number of infectious persons (n). an additional case is considered that if the time t is longer than the age of the air τn, most of the virus-laden aerosols have left the room with the exhaust, before the inactivation can take place. therefore, this concentration during the steady state situation is called cτ(t). with τn regarding equation ( ) all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . the predicted infection risk via aerosols can be calculated by equation ( ) and ( ). for the calculation of pira the following assumptions must be considered:  the aerosols are ideally mixed in the room  the near field (up to approx. . m distance from the emitting person) can contain a much higher virus-laden aerosol concentration  the air, which is introduced into the room, is free of virus-laden aerosols (e.g. outside air)  no deposition of small particles is considered, because the settling time is longer than the stability of the virus and the deposition rate would therefore be substantially smaller than the inactivation the pira calculation model was validated by using parameters of several known outbreaks during the sars-cov- pandemic. twelve different scenarios either scientifically published or registered by the local health authorities were selected (a-l). the boundary conditions for the calculations of these situations can be found in table . all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint *due to partly missing information, assumptions were made, especially for window ventilation. the assumptions are based on information from the persons involved on how the windows were opened and closed in combination with weather data at the time. ** it was assumed that the local regulations for fresh air supply were fulfilled. ***geometry and ventilation rate due to [ ] ****attack rate was simplified as percentage of persons infected. no separation regarding infection attack rate (measured serologically) and illness attack rate (persons with symptoms or laboratory-confirmed) was performed. ***** it was assumed that a school lesson lasts minutes. the infection events used for the validation of the model are shown in table with the necessary parameters for the calculation. in the following, the comparison between the documented attack rate (ar) and the pira is drawn. the q used here was calculated according to equation ( ) with the assumption that the cases emitted particles as measured in [ , ] . due to the high spread of the particle emission e and the unknown proportions of breathing, speaking, singing and shouting as well as the respiratory volume flows, simplified a-priori assumptions were made. to take into account the effects of the uncertainties regarding q, qb and especially with window ventilation on q, these values were further varied -q by +/- %, qb by +/- % and q by +/- %, individually and in combination, which then lead to a minimum pira and maximum pira. table ). all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint from the pira model, it can be calculated how much volume flow per hour of exposure time is required to not exceed a certain pira. the results are shown in figure . it can be seen that for a pira of % a volume flow of clean air of m³/h and hour of exposure has to be supplied to the room (see table ), whereas for two hours m³/h will be necessary for the same pira. as a regression of the calculated results presented in figure equation ( ) was derived. using equation ( ) the required volume flow per hour of exposure time can be calculated. this information refers to the steady state if the product of ach and t is higher than . , see all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint table lists practical examples of the required volume flows depending on the exposure time and pira. table in table perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint in outbreak e, there is only little documentation of the infection process, and further contact between some of the persons has occurred in a restaurant afterwards. furthermore, it has not been determined whether the infection can be attributed to only one person. the high ar after a short time of exposure allows the conclusion that either two index persons were present or that the exposure time was prolonged by the meeting in a restaurant. in outbreak f, the group was not together for the entire time and some of the subjects continued rehearsing in another room. for this reason, the exposure time for the whole group was lower and therefore this may account for the lower ar than calculated by pira is given. in outbreak l an air exchange rate of /h was assumed. a relatively small change in the assumed volume flow has a significant influence on the result of pira (where the total exposure time was used). furthermore, it cannot be excluded that droplet transmission may also have happened. secondly, many assumptions were made, therefore it is not clear if the formula is already optimal, perhaps further optimization during the course of the pandemic is possible if further knowledge is available. third, the calculation model does not consider the sedimentation behavior of particles. it is known that at higher air velocities and especially at high turbulence the sedimentation behavior increases. in typical indoor air flows this decrease is about % per hour. compared to the uncertainty of the overall emission rate, this effect is not significant. fourth, the calculation model assumes a homogeneous distribution of the particles in the room air. practically however the ventilation effectiveness is locally very different. the differences can be slightly greater than %. finally, it must be noted that the aerosol concentration is significantly higher in the near field of the emitting person and the results of pira are not valid within the generally accepted . m distance rules. it was shown in this investigation that it was possible to calculate the risk of an infection via aerosols for situations where the long-distance transmission is more important. by using the model presented here, a good agreement to previous infection outbreaks in different settings and different attack rates was achieved. previous retrospectively determined quanta emission rates usually assumed a stationary state. however, if the concentration process is important for the total amount of inhaled virus-laden aerosols (usually at ach x t < ), then a stationary observation leads to an incorrect boundary condition. the time-dependent viability of the virus also plays a significant role. here, the influence of the viability is higher at low air change rates compared with high ones, because the virus stays in the room air for a longer time period and the proportion of inactivated pathogens increase. however, the effect of time- dependent viability is not that important that a low air change rate has an overall positive effect. to reduce the risk of infection via aerosols the necessary volume flow of virus-free air depending on the exposure time can be seen in figure . this figure may be helpful to all rights reserved. no reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in the copyright holder for this this version posted october , . . https://doi.org/ . / . . . doi: medrxiv preprint implement measures, like increasing the virus-free air supply rate. furthermore, the number of exposed persons has to be kept in mind. an infection risk of % may result in one infected person in a two-person office, but in infected persons in a room with persons. predicting the infection risk via aerosols and knowing the important parameters can help in the selection of appropriate preventive actions. declarations evidence for probable aerosol transmission of sars-cov- in a poorly ventilated restaurant airborne route and bad use of ventilation systems as non-neglible factors in sars-cov- transmission quantifying sars-cov- transmission suggests epidemic control with digital contact tracing airborne transmission of sars-cov- : the world should face the reality airborne spread of measles in a suburban elementary school airborne contagion and air hygiene: an ecological study of droplet infections applying the wells-riley equation to the risk of airborne infection in hospital environments: the importance of stochastic and 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dynamics in viral shedding and transmissibilitiy of covid- the airliner cabin environment and the health of passengers and crew investigation of a superspreading event preceding the largest meat processing plant-related sars-coronavirus outbreak in germany community outbreak investigation of sars-cov- transmission among bus riders in eastern china a large covid- outbreak in a high school days after schools' reopening, israel covid- outbreak associated with air conditioning in restaurant transmission of severe acute respiratory syndrome coronavirus during ling flight quantitative assessment of the risk of airborne transmission of sars-cov- -infection: prospective and retrospective applications the authors received no specific funding for this work. the authors declare no competing interests. the authors declare that they followed the appropriate research guidelines. key: cord- -qz g v u authors: livadiotis, george title: statistical analysis of the impact of environmental temperature on the exponential growth rate of cases infected by covid- date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: qz g v u we perform a statistical analysis for understanding the effect of the environmental temperature on the exponential growth rate of the cases infected by covid- for us and italian regions. in particular, we analyze the datasets of regional infected cases, derive the growth rates for regions characterized by readable exponential growth phase in their evolution spread curve and plot them against the environmental temperatures averaged within the same regions, derive the relationship between temperature and growth rate, and evaluate its statistical confidence. the results clearly support the first reported statistically significant relationship of negative correlation between the average environmental temperature and exponential growth rates of the infected cases. the critical temperature, which eliminates the exponential growth, and thus the covid- spread in us regions, is estimated to be tc = . ± . f. the daily number of new cases infected by covid- is currently exponentially growing for most countries affected by the virus. however, this exponential growth rate varies significantly for different regions over the globe. it is urgent and timely to understand the reasons behind this regional variation of the exponential growth rates. little information is known about this matter, while there are indications that the environmental temperature may be a factor; for instance, northern and colder us and italian regions experienced much more incidents than others. typically, the evolution curve of the spread of the coronavirus initiates with a pre-exponential phase characterized by a mild logarithmic growth, followed by the outburst phase of the exponential growth. social-distancing measures against the spread may affect the evolution curve in a way that the exponential growth slows down and starts to decay, depending though on the effectiveness and applicability of these measures. however, after the decay of the spread at some place, new infected cases may outburst in other places, marked with insignificant number of cases until that moment. then, a newly growth phase may appear. for example, fig. (left) shows the evolution curve of spread for the infected cases in mainland china; clearly, we observe the whole growth−decay cycle, as well as, a new re-growth phase. super-strict measures, such as complete shut down and quarantines, can successfully lead to the deceleration of the exponential growth of infected cases (giugliano, ) . unfortunately, they cannot be successfully applied and followed within vast regions, and especially, for a long and indefinite period of time. inevitably, measures may be loosened during the decay phase, leading to the birth of an equally disastrous re-growth phase. us & italy (right); phases (color-coded): pre-exponential (pre-exp), exponential (exp) growth, decelerated growth, decay, and possibly, a re-growth. day t= corresponds to / / for china, / / for italy, / / for us. evolution in china cases follows the whole growth-decay cycle, and a new re-growth phase. italian cases are characterized by a milder exponential rate, entered the phase of decelerated growth on march . us suffers with a larger exponential rate, and it is not clear whether has entered the decelerated growth phase. the exponential growth rate for china rose as high as λ= . ± . , while for italy and us the rates were λ= . ± . and . ± . , respectively (with correlation coefficient > . ). the exponential growth is the most effective phase for the evolution curve of infected cases; and the most important question regarding this evolution is still open (black et al. ) : what can influence the exponential growth rate, and thus, "flatten the curve"? measures, strict or not, may affect the evolution of new infected cases, by shifting the spread curve from the exponential to the decelerated growth. it should be noted though that measures do not affect the exponential growth rate itself, but only the period of time that this exponential phase applies. then, what factors do affect the exponential growth rate? the age distribution in the place where the outburst occurs is unlikely to be a factor; indeed, the number of new cases is known to be positively correlated with age, however, the exponential growth rate (china: . ; us: . ; italy: . -decreasing rate) appears to be negatively correlated to the age median of these countries (china: . ; us: . ; italy: . -increasing age); hence, the age is likely irrelevant to the rate variations. in addition, culture in social activities may be a factor; for example, this might be contributing in the observed differences among the exponential rates in the cases of china, italy, and us ( fig. ) . however, what is causing the major variation of exponential rates among different regions of the same culture? it is apparent that culture does not constitute the main factor influencing the exponential rate. figure shows the regional variation of infected cases (left) and average winter temperature (right) in italy. the possible negative correlation, observed between regional number of infected cases and winter temperature in italy, is an indication of the influence of temperature on the exponential growth, but it certainly does not constitute a necessary condition. the reason is that the map plots the total number of the infected cases n t , which does not depend only on the exponential rate λ, but also on the initial number of cases n . it is generally accepted that the initial infected cases in italy were travelled directly from china; since some destinations are more favorable than others, then, the initial number of cases n , as well as the current number of cases n t (which is proportional to n ), should be subject of regional variation. therefore, there is a non-negligible possibility, the observed regional variation of the number of infected cases n t to be caused by the regional distribution of the initial cases n . in such a case, main airport cities would have incredibly high number of infected cases outplaying a possible negative correlation of daily infected cases with regional average temperature t; the latter may be one of the reasons of the high numbers of cases observed in new york city and rome. on the other hand, in their letter to the white house, members of a national academy of sciences committee said that "there is some evidence to suggest that [coronavirus] may transmit less efficiently in environments with higher ambient temperature and humidity; however, given the lack of host immunity globally, this reduction in transmission efficiency may not lead to a significant reduction in disease spread without the concomitant adoption of major public health interventions" (relman, ) . nevertheless, it has to be stressed out that there were no statistical analyses focused on the exponential growth rates of the infected cases in regions with different temperatures. for instance, several authors (e.g., pawar et al., ; yao et al., ) found insignificant correlations between temperatures and confirmed cases. however, their analysis was performed on the number of the infected cases n t , which is subject to the randomness of the initial cases n as explained above, and not to the exponential growth rate λ, which is dependent on physical characteristics of the coronavirus, binding protein, and environment. analysis of regional cases can show whether the speculated negative correlation between temperature and number of infected cases is true, meaning a negative correlation between temperature and exponential growth rate. if the environmental temperature plays indeed a substantial role on the virus spread, then, this can provide promising results, such as, the estimation of the critical temperature that may eliminate the number of daily new cases in heavily infected regions. the purpose of this paper is to improve understanding of the effect of environmental temperature on the spread of covid- and its exponential growth rate. then, we calculate the exponential growth rates of infected cases for us and italian regions, derive the relationship of these rates with the environmental temperature, evaluate its statistical confidence, and determine the critical temperature that eliminates this rate. a standard model for describing the evolution of the infected cases by viruses is given by ( ) ( ) ; n t is the number of total infected cases evolved from the initial n cases, n max is the maximum possible number of infected cases; λ is the exponential growth rate, and becomes clear for x t << , where i is negligible, leading to: the function of negative feedback i models factors that flattens the curve, such as, the measures taken against spreading. while these factors are not affecting the exponential growth rate λ, they become more effective as the number of cases increases, getting closer to n max ; exponent b controls the effectiveness of these factors; strict {loose} measures correspond to smaller {larger} values of b. figure shows the evolution curve of the number of new (Δn t = n t+ −n t ) and total infected cases (n t ) and how this curve flattens for stricter measures (smaller values of b). as observed in fig. (b) , stricter measures, nicely modeled by decreasing b, do not affect the exponential rate λ but they successfully flatten the curve. however, the same can be achieved by downgrading the exponential growth rate. it is apparent, then, how much useful would it be to know the factors that can flatten the curve by decreasing directly the exponential rate. applied measures could be loosen and shorter! model ( ) originates from the logistic map family (e.g., livadiotis, ; and references therein; wu et al. ) ; other complicate versions, such as, the susceptible-infectious-recovered models (e.g., ciarochi, ) may be expressed by multi-dimensional differential or difference equations (e.g., elaydi, , and references therein; livadiotis et al. ), but still, the curve flattening is governed by the same features. the two composites, the exponential growth e and the negative feedback i, are just the main and necessary conditions for reproducing the growth-decay phases of the spread curve. their interplay shows how the spread curve can be flattened as a result of stricter measures, independently of the existent exponential rate. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . what are the main factors that can affect the exponential growth rate λ of covid- spread? the rate λ is expected to have positive correlation with the reproduction number r (e.g., proportional to its logarithm), and negative correlation with the incubation period τ (e.g., inverse proportional) (milligan and barrett, ) . the number r is a measure of how contagious a disease is; it provides the average number of people in a susceptible population that a single infected person will spread the disease to over the course of their infection (ciarochi, ) , and depends on the physical characteristics of coronavirus (hao ) . the incubation period τ is the time elapsed between exposure to coronavirus and first symptoms; during this period, an infected individual cannot infect others; other characteristic periods and time intervals are the latent period between exposure and infection, and the generation time, mostly concerned with transmission process (nishiura, ) . characteristic values for covid- are τ~ - days and r ~ - (chen, ) . the rate expression can be written as , and involves all the physical characteristics of the mechanisms of infection and the environmental interactions; this can be easily derived, considering difference equations (that is, iterated discrete maps) (e.g., see: livadiotis and elaydi, ; kwessi et al., ; dayeh et al, ) . setting the time to be given in discrete τ-steps, then, which can be written in terms of eq. ( ), where the exponential rate is given by: the main factors that can affect the exponential rate λ are: (a) culture in social activities, and (b) environmental temperature and/or other thermodynamic parameters. intense cultural and social activities have reasonably a positive correlation with r . as previously mentioned, measures against the virus spread do not effectively influence the exponential growth rate; e.g., they do not change the culture in social activities, which are characteristics of the particular population, but they can just cease these activities for some period of time. on the other hand, the environmental temperature t can affect all the parameters influencing exponential rate. we approach this dependence by (i) a linear approximation of the phenomenological relationship between exponential rate and temperature, and (ii) the connection of reproduction number with arrhenius behavior (with negative activation energy): (i) the temperature can affect the physical properties of coronavirus, such as, the incubation time τ, as well as, the reproduction number r that depends on these physical properties (hao, ) . a linear approximation absorbs the (weak) temperature dependence of any parameters involved in the exponential rate; then, eq.( ) gives: where we set the intercept to be given in normal conditions of atmospheric temperature and pressure (ntp) (that is, t= c , p= atm). then, we rewrite the exponential rate as: (ii) coronavirus uses their major surface spike protein to bind on a receptor -another protein that acts like a doorway into a human cell (wrapp et al., ) . the whole process is a slow chemical reaction, where . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint the mechanism behind can lead to rates negatively correlated with temperature, i.e., increasing rate with decreasing temperature. this is consistent to reaction rate expressed by the arrhenius exponential with and benson, ) . then, the effective reproduction number ( ) r t is expressed as a product combining the reproduction number in the absence of temperature effect, r  , and the arrhenius exponential rate, namely, then, eq. ( ) gives we rewrite this expression as: reactions of negative activation energy are barrier-less, relying on the capture of the molecules in a potential well. increasing {decreasing} the temperature leads to a reduced {gained} probability of the colliding molecules capturing one another. exponential spread is mainly related to outdoors activities while the decelerated growth caused by effective measures is related to indoors activities. therefore, as long as the exponential growth takes place, the environmental temperature has an effective role on the chemical reaction between virus and spike protein. due to the negative activation energy, decreasing the environmental temperature reduces the probability of virus-protein reaction, thus the virus may stay inactive on air or surfaces and eventually die. it should be noted that both the models ( b) and ( b) consider that the exponential rate λ, or the reproduction number r , are subjects to a component influenced by the culture in social activities (intercept λ ) and a component mostly influenced by the temperature (slope p ). in this way, the slope may indicate to some universal quantity involved, such as, the (negative) activation energy. next, we employ the above two expressions of exponential rate λ and temperature t, eqs.( a, a), in order to set the two types of statistical models for fitting (Τ, λ) measurements for us and italian regions. we use publicly available datasets of: ( ) average enviromental temperature of us and italian regions (e.g., see: www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/climate-normals; it.climate-data.org; www.weather-atlas.com); ( ) time series of the number of daily infected cases of us and italian regions (e.g., see: www.thelancet.com; www.protezionecivile.gov.it). we analyze the datasets of regional infected cases in us and italy, derive the relationship of the exponential growth rate of the number of cases with temperature, and evaluate its statistical confidence. first, we derive the exponential growth rates of the infected cases characterizing each examined region of italy and us; then, we plot these values against the environmental temperatures of each region, and perform the corresponding statistical analysis. we proceed according to the following steps: (i) collect the time series of the current infected cases n t for all us and italian regions. for each of the us and italian regions, we plot log(n t ) and log(Δn t ) with time t, detect the time intervals of linear relationship corresponding to the phase of exponential growth, fit the datapoints within this region, and derive the slope (on linear-log scale), that is, the exponential growth rate λ. the total n t and new cases Δn t should be characterized by the same exponential . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . rate, λ, thus the slopes resulted from the linear fits of log(n t ) and log(Δn t ) with time are (weighted) averaged (fig. ) . (iii) collect environmental temperature data and calculate the temperature averaged over the whole examined region. the incubation period τ is longer than the time scale of a single day or night, thus the temperature is averaged over the daily and nightly measurements. (iv) co-plot all the derived sample values (Τ±δΤ, λ±δλ), where each pair corresponds to each examined region; then, apply a linear fitting in order to derive the linear relationship between t and λ, as well as evaluate the statistical confidence of this relationship; repeat the same for all us and italian regions. determine the critical temperature t c for which the rate becomes negligible; to eliminate the uncertainties of t c as a fitting parameter, we perform the linear fitting with the statistical model repeat (iv) and (v) with pairs of (t - ±δt - , λ±δλ); we estimate again t c by performing the linear fitting with the statistical model λ=λ (- +Τ c /t) instead of λ=p +p •t - . linear fitting of the number of the total n t and new Δn t infected cases with time (on linear-log scale) for the states of california and illinois, where the slope reads the exponential rate λ. the resulted rates from the linear fitting of log(n t ) (black) and log(Δn t ) (red) are (weighted) averaged (blue). the phases are color-coded as in figure . the hypothesis to be tested is that the exponential growth rate λ varies linearly with temperature; (x is set to be the temperature or its inverse). this is tested by examining the chi-square corresponding to the fitting of the two-parameter linear statistical model h is the α-th diagonal element of its . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . , α= , , where the derivatives are numerically derived. we will use two linear statistical models, (a) , as given by eqs.( a, a) ; both can be written with the linear expression: the statistical confidence of the dependence of the exponential growth rate on the environmental average temperature may be sufficiently high for the acceptance of any of the two statistical models. the goodness of the fitting of each model is evaluated using two types of statistical tests, the "reduced chi-square", the "p-value of the extremes", and their combination (e.g., frisch et al., ; schwadron et al., , fuselier et al., , while student's t-test is also used for evaluating the statistical confidence of the derived slopes: -reduced chi-square: the goodness of a fit is estimated by the reduced chi-square value, -student's t-test: this is another test for evaluating the statistical confidence of the slope derived from the linear fitting of the temperature-rate sample points (t i ±δt i , λ i ±δλ i ) and (t i - ±δt i - , λ i ±δλ i ). we examine, whether the slope p ±δp has significant difference from the zero slope (null hypothesis: slope is zero), by performing the student's t-test with t m =p /δp , where the corresponding p-value is derived from the integration of t-distribution . the student's t-test is not passed for the null hypothesis that they examined slope equals zero, when the corresponding p t -value is less than the acceptable confidence limit of . ; then, the null hypothesis is rejected, meaning the slope has statistically significant difference for zero. in addition, we examine the slopes estimated for us with those estimated for italian regions, by deriving the linear fitting of log(n t ) or log(Δn t ) with time t within the region of exponential growth phase, resulted to the respective rates (given by the fitted slope); their weighted averages are shown in table for us and in table for italian regions, while plotted against the average regional temperature in figs. and , respectively. the method of weighted fitting for double uncertainties (x i ±δx i , λ i ±δλ i ), as described by fasano and vio, ) , is used for estimating the fitting parameters λ , t c , together with their statistical, propagation, and total errors. the fits of the linear statistical model with temperature, x i =t i , (left panels in figs. , ), as well as of the alternative statistical model with inverse temperature, (right panels in figs. , ) , are both characterized with high statistical confidence, attaining high p-values (> . ) and reduced chi-squares red  values (close to ); also, both fits provide similar estimations of t c . the fitting results are shown in table . we also examine whether the sample points (t i ±δt i , λ i ±δλ i ) are subject to statistically significant concentrations or rarefactions, namely, whether possible heterogeneities within the distribution of sample points plays significant role in the fitted relationship. for this, we derive the temperature-rate relationship and its statistical confidence by fitting the homogenized set of sample points, instead of the raw sample points; then, we examine whether the fitting parameters differ from those derived from fitting the raw sample points. we homogenize the sample points by grouping them in temperature binning of Δt ~ c (e.g., see: livadiotis & desai ). we estimate the weighted mean and error of the rates included in each bin. in the case of us regions we also performed a homogenization of rates, by grouping the temperaturebinned means in rate binning of Δλ ~ . d - . in the case of sample points with inverse temperatures, (t i - ±δt i - , λ i ±δλ i ), the procedure is exactly the same. homogenized datasets result in a smooth relationship between the values of binned temperature and rate, as it can be observed in the plots of rate against temperature or inverse temperature (left or right lower panels, respectively), and for both us and italy regions (figs. and , respectively) . the results are highly supportive of the negative correlation between rate and temperature. the results are shown in table . we observe that the linear relationships of the growth rate with temperature or inverse temperature are characterized by high statistical confidence for the homogenized datasets (p-values much higher than significant limit of . ; red  far from the significant limits of . and ). therefore, the arrangement of sample points do not affect significantly the fitting results. in addition, as shown in tables and , the linear fits of sample points (t i ±δt i , λ i ±δλ i ) and (t i - ±δt i - , λ i ±δλ i ) do not pass the student's t-test for the null hypothesis that their slopes equals zero, i.e., the corresponding p t -values are less than the acceptable confidence limit of . ; therefore, the negative correlation of environmental temperature with the exponential rate is statistically significant (accepted with confidence %). . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . ( ) the exponential growth rate and its uncertainty is the weighted averaging of the rates derived from total and new infected cases; ( ) the environmental temperature is averaged over the time period, from τ~ days before the appearance of the st case, to st april; ( ) the standard deviation of temperature is given by the half difference between highest and lowest values within the examined time period, divided by √ (similar to the standard deviation for a sinusoidal function); ( ) ny: the temperature refers to the new york city, instead of the whole state, which suffers from the vast majority of the state infected cases. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint figure . linear fitting of rates with (left) temperatures and (right) inverse temperatures for us regions. the fitting is weighted with double uncertainties (on both the temperature and rate values). the analysis is first completed for the raw measurements (upper) and then repeated for the binned averages (lower). . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint figure . as in figure , but for italian regions. table . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . in order to improve the statistics of the estimated critical temperature, we combine the sample points (t i ±δt i , λ i ±δλ i ) of us and italian regions. first, we perform the student's t-test to compare the slopes corresponding to us and italian regions; we find high p t -values (> . ) for both fits of x=t and x=t - , thus, the two populations are likely characterized by the same slope. tthe respective intercept λ does not pass the same test, i.e., the intercepts corresponding to us and italian regions are likely different. a universality may characterize the slopes of fits x=t or x=t - , i.e., next, we perform the linear fits of the sample points (t i ±δt i , λ i ±δλ i ) and (t i - ±δt i - , λ i ±δλ i ) for the mixed set of us and italian data, once the rates of the italian regions are shifted by Δλ; the optimal fitting is obtained for that shift Δλ, for which the reduced chi-square is ~ , the p-value of the extremes is ~ . , and the combined measure ~ (see previous section). figure shows how the combined datasets of temperaturerates from us and italian regions lead to the optimal fitting. (note that the optimization is not performed for the binned datasets, since they are characterized by smaller p-values -see, figs. and ). the results are shown in table ; we observe that the optimization is reached for two values of the shift Δλ; we estimate the weighted average of the results corresponding toe the two shifts. the weighted mean is performed separately for the fitting cases of x=t and x=t - ; however, the weighted mean of the critical temperature is performed for all four results. fitting of datasets combined for us and italian regions, with the latter's rates shifted by Δλ. the optimal fitting corresponds to shifts Δλ~ . and ~ . , for which the reduced chi-square is ~ , the pvalue of the extremes is ~ . , and the combined measure ~ . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . figure . relationship of the reproduction number r and its uncertainty with environmental temperature t. according to this, new affected cases cease (r = ) when temperature climbs to t c~ c or (~ f ). up-to-date there is no systematic statistical analysis of the effect of the environmental temperature t (and possibly other weather parameters) on the exponential growth rate of the cases infected by covid- , while a statistically confident relationship between temperature and growth rate (either with positive or negative correlation) is still unknown. the presented analysis led to a statistically confident relationship of negative correlation between the exponential growth rate and the average environmental temperature, derived for us and italian regions. in particular, we analyzed datasets of regional infected cases in us and italy, derived the exponential growth rates for each of these regions and plotted them against environmental temperatures averaged within the same regions, derived the relationship of temperature -growth rate, and evaluated its statistical confidence. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . the performed statistical analysis involved fitting of linear statistical models with the datasets of environmental temperature (or its inverse) and exponential growth rate, finding their relationship, and evaluating its statistical confidence. the two linear models developed and used for the statistical analysis are (a) the statistical confidence of fitting was evaluated using the reduced chi-square values, the p-value of extremes, and a testing measure that combines both of these values. also, the statistical confidence was also evaluated using the student's t-test, where the derived slopes compared to a hypothetical zero slope. the sample points of temperature (or inverse temperature) and exponential growth rate were also tested for statistically significant concentrations or rarefactions; namely, for possible heterogeneities within the distribution of sample points that could have significant role in the results. the statistical analysis of the homogenized temperature-rate data points concluded that the negative correlation between temperature and exponential rate is stable, having no statistically significant variability due to concentrations or rarefactions, and it is characterized by a high statistical confidence. we also performed a student's t-test and ensured that the difference between two sample means of us and italian regions is not statistically significant. a possible universality may characterize the slope of the temperature-rate relationship. this verifies the modeling developed and used by this analysis, where the exponential rate λ, or the reproduction number r , are subjects to a component influenced by the culture in social activities (intercept λ ) and a component influenced by the temperature (slope p ). in this way, the slope may indicate to a universal quantity involved, such as, the (negative) activation energy. since the derived slopes for us and italian regions are characterized by no statistically confident difference, we improved the statistics of the estimated fitting parameters by combined the sample points of us and italian regions. from the derived relationship, among others, we were able to derive the values of the (negative) activation energy e a , and the reproduction number r at normal conditions and how this depends on temperature. therefore, the results clearly showed that there is indeed statistically significant negative correlation of temperature on the exponential growth rate of the cases infected by covid- . figure shows the anticorrelation between the mapped exponential rates and average environmental temperature of the usa regions examined by this analysis, which they are characterized by readable exponential growth phase in their evolution spread curve. figure . anti-correlation between the spatial distributions of the exponential growth rates of the infected cases (left) and the average environmental temperature (right). . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted april , . . https://doi.org/ . given the negative correlation of the environmental temperature with the exponential growth rate, it was reasonable to ask for the critical temperature that eliminates the exponential rate, and thus the number of daily new cases in infected regions. this was found to be t c~ . ± . f for us regions. it is straightforward to ask when the environmental temperature will climb above this critical value. as an example, figure plots the daily average temperatures in san antonio, texas, shown that will be clearly above the estimated t c threshold in the second half of may. figure . according to the statistically confident relationship between exponential growth rate of infected cases shown in fig. , the critical temperature, which eliminates the exponential growth, and thus the covid- spread, is t c = . ± . f . the plot shows also the may-june daily, nightly, and h-averaged environmental temperatures in san antonio, texas, averaged over the last three years. the daily average temperatures will be clearly above the estimated t c threshold in the second half of may; thus, the plot suggests a possible date for loosening the strict measures in san antonio, that is, may . the resulted high statistical confidence of the negative correlation of the environmental temperature on the exponential growth rate of the cases infected by covid- is certainly encouraging for loosening super-strict social-distancing measures, at least, during the summery high temperatures. however, we are, by no-means, recommending a return-to-work date based only on this study. but we do think that this should be part of the decision, as well as an inspiration for repeating the same analysis in other heavily infected regions. the steps of these analyses may be followed as: (i) identify different outbreaks in regions with the same culture in social activities and different environmental temperature; (ii) estimate the exponential growth rates for these regions from the time series of infected cases; (iii) plot the derived rates against the environmental temperature averaged for these regions, and repeat the analysis of this study to determine the temperature-rate relationship and its statistical confidence. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted april , . . https://doi.org/ . how to flatten the curve of coronavirus, a mathematician explains a mathematical model for simulating the phase-based transmissibility of a novel coronavirus how covid- and other infectious diseases spread: mathematical modeling a discrete mathematical model for the aggregation of β-amyloid an introduction to difference equations fitting a straight line with errors on both coordinates decades-long changes of the interstellar wind through our solar system low energy neutral atoms from the heliosheath negative activation energies and curved arrhenius plots. . theory of reactions over potential wells time variations in the generation time of an infectious disease: implications for sampling to appropriately quantify transmission potential effects of temperature on covid- transmission rapid expert consultation on sars-cov- survival in relation to temperature and humidity and potential for seasonality for the covid- pandemic solar radiation pressure and local interstellar medium flow parameters from ibex low energy hydrogen measurements generalized logistic growth modeling of the covid- outbreak in provinces in china and in the rest of the world no association of covid- transmission with temperature or uv radiation in chinese cities key: cord- -q if li authors: simpson, ryan b.; zhou, bingjie; alarcon falconi, tania m.; naumova, elena n. title: an analecta of visualizations for foodborne illness trends and seasonality date: - - journal: sci data doi: . /s - - -x sha: doc_id: cord_uid: q if li disease surveillance systems worldwide face increasing pressure to maintain and distribute data in usable formats supplemented with effective visualizations to enable actionable policy and programming responses. annual reports and interactive portals provide access to surveillance data and visualizations depicting temporal trends and seasonal patterns of diseases. analyses and visuals are typically limited to reporting the annual time series and the month with the highest number of cases per year. yet, detecting potential disease outbreaks and supporting public health interventions requires detailed spatiotemporal comparisons to characterize spatiotemporal patterns of illness across diseases and locations. the centers for disease control and prevention’s (cdc) foodnet fast provides population-based foodborne-disease surveillance records and visualizations for select counties across the us. we offer suggestions on how current foodnet fast data organization and visual analytics can be improved to facilitate data interpretation, decision-making, and communication of features related to trend and seasonality. the resulting compilation, or analecta, of visualizations of records and codes are openly available online. disease surveillance systems worldwide face increasing pressure to maintain and distribute data in usable formats with clearly communicated visualizations to promote actionable policy and programming responses . decade-long efforts to sustain surveillance systems improve early outbreak detection, infection containment, and mobilization of health resources [ ] [ ] [ ] [ ] and create adaptive, near-time forecasts for disease outbreaks , . web-based platforms provide access to more accurate, timely, and frequent surveillance data. the world health organization's (who) flunet, for example, provides time-referenced data on worldwide influenza . publicly available downloads increase the flexibility for analyses and enables adaptive research due to frequent and timely reporting. the pandemic of novel coronavirus disease (covid- ) serves as a vivid demonstration of how limited access to publicly available high-quality data can stymy research. as the quantity and diversity of data available for processing, synthesizing, and communicating increases, new visual analytics, including complex multi-panel plots, must be considered to monitor trends, investigate seasonality, and support public health planning . these visualizations, and the methodologies used to generate them, must be standardized to enable comparability across time periods, locations, at-risk populations, and pathogens. however, current surveillance systems, including foodborne disease surveillance in the united states, often compress time series records to simplistic annual trends [ ] [ ] [ ] [ ] [ ] and describe seasonality by the month(s) with the highest cases per year or the first month of outbreak onset [ ] [ ] [ ] [ ] [ ] [ ] . visualizations using these annual trends or broad assessments of seasonality fail to utilize the full complexity of surveillance data and in some cases may be misleading. more specifically, these visualizations fail to provide detailed examination of how long-term trends change over time, how seasonality estimates vary by year or across locations, or how peak timing and amplitude estimates could change over time. the cdc foodborne disease active surveillance network (foodnet) provides preprocessed population-based foodborne-disease surveillance records and visualizations via foodnet fast, a publicly available data portal , . the foodnet fast platform contains rich demographic data, including age group, gender, and ethnic group, valuable for a broad spectrum of analyses. the visualizations aim to aid users in identifying trends of nine laboratory-confirmed foodborne diseases in select counties from ten us states and nationally. however, in the present form and due to substantial data compression, the available data and visualizations provided are limited in scope preventing the foodnet fast allows data download and visualization of these diseases for a user-specified time period. data downloads include information on the incidence of confirmed cases, monthly percentage of confirmed cases, distribution of cases by pathogen, and totals of cases, hospitalizations, and deaths. for multi-year periods, the portal aggregates totals and monthly percentages into single statistics for the full time period selected rather than showing individual years. this aggregation ensures case anonymity but monthly time units minimize the refinement of trend and seasonality analyses. to calculate monthly percentages of confirmed cases for all diseases in one year and one location, we had to download each state-year combination individually, for a total of files in ms excel format. to create a time series of total monthly cases by pathogen and location, we used data from two tables in each data download: annual counts of confirmed cases (long format) and monthly percentage of confirmed cases (wide format). we transposed the monthly percentages of confirmed cases from wide to long format and then multiplied them by the annual counts of confirmed cases (supplementary figure s ). since the provided monthly percentages are rounded to digit in the data download, calculated counts slightly under-or over-estimate annual totals. we did not round non-integer cases in our calculated time series to best preserve the monthly distribution of cases from the original data download. a monthly time series of confirmed cases of hospitalizations or deaths could not be reconstructed as described because no information is provided on their monthly percentages. we next calculated disease rates using confirmed monthly cases and annual population data. rates are preferred over counts since changes in counts could be a direct result of changes in the population catchment area of a surveillance system. the number of counties and states monitored in foodnet increased between and and has remained constant to date since (supplementary table s ). we downloaded county-level population estimates from the , , and us census bureau interannual census reports, which provide annual population estimates [ ] [ ] [ ] . we then estimated state-level foodnet population catchment area by adding all mid-year (july st ) populations of surveyed counties monitored in each year. next, we calculated the united states population catchment area by adding all state-level estimates for all surveyed counties for each year. finally, we developed a time series of monthly rates per , , persons for each pathogen and location by dividing monthly counts by annual population estimates and multiplying this quotient by , , . in addition to monthly rates, we calculated yearly rates by adding all monthly counts each year, dividing by the annual population, and multiplying this quotient by , , . modeling trends and seasonality. we estimated trend and seasonality characteristics using negative binomial harmonic regression (nbhr) models, which are commonly used to analyse count-based time series records with periodic fluctuations [ ] [ ] [ ] . these models include harmonic terms representing sine and cosine functions, which allow us to fit periodic oscillations. the regression parameters for these harmonic terms serve as a base for estimating important characteristics of seasonality: when the maximum rate occurs (peak timing) and the magnitude at that peak (amplitude). we calculated peak timing, amplitude, and their confidence intervals from nbhr model coefficients using the δ-method, which allow us to transform the regression coefficients of the model to seasonality characteristics based on the properties of the basic trigonometric functions (supplementary table s ) , . to estimate annualized seasonality characteristics, we applied a nbhr model for each study year and location with the length of the time series set to to represent the months of the year. we also estimated seasonality characteristics for the full time period. to show average trends across the entire -year period, we fit a nbhr model with three trend terms (linear, quadratic, and cubic) where the length of the time series varied according to when foodnet began surveying that location from to months. the selection of three polynomial terms was driven by the clarity of interpretation as a monthly increase and the potential for overall acceleration or deceleration, although other ways of assessing the trend such moving averages and spline functions could be also explored. plot terminology. we develop multi-panel visualization techniques using the best practices of current data visualization resources , and our own research , , . a multi-panel plot, as defined by our earlier work, "involves the strategic positioning of two or more graphs sharing at least one common axis on a single canvas . " these plots can effectively illustrate multiple dimensions of information including different time units (e.g. yearly, monthly), disease statistics (e.g. pathogens, rates, counts), seasonality characteristics (e.g. peak timing, amplitude), and locations (e.g. state-level, national). we use the following common, standardized terminology across visualizations to ensure comprehension: • disease -each of the nine reported foodnet infections, including campylobacteriosis (camp), listeriosis (list), salmonellosis (salm), shigellosis (shig), infection due to shiga toxin-producing escherichia coli o and non-o (ecol), vibriosis (vibr), infection due to yersinia enterocolitica (yers), cryptosporidiosis (cryp) and cyclosporiasis (cycl) • monthly rate -monthly confirmed cases per , , persons • yearly rate -total confirmed cases in a year divided by the mid-year population of all surveyed counties in that location (cases per , , persons) • frequency -the number of months reporting the disease rates in the same range • peak timing -the time of year according to the gregorian calendar that a disease reaches its maximal rate; for monthly time series, peak timing ranges in [ , [, i .e. from . (beginning of january) to . (end of december) • amplitude -the mathematical amplitude, or the midpoint of relative intensity; for nbhr models, the amplitude estimate reflects the ratio between the disease rate at the peak (maximum rate) and the disease rate at the midpoint (median rate) • foodnet surveyed county -the counties under foodnet surveillance as of • non-surveyed county -all remaining counties within a surveillance state as of . we present our analecta of visualizations allowing to describe trend, examine seasonal signatures, curves depicting characteristic variations in disease incidence over the course of one year, and understand features of seasonality, such as peak timing and amplitude across locations and diseases. we illustrate all visualizations using salmonellosis for the united states from - . the full analecta with time series data and code are available on our website (https://sites.tufts.edu/naumovalabs/analecta/) with data and code also available on figshare . describing trend. the interpretability of trends in a time series plot is greatly affected by the length and units of the time series. foodnet fast aggregates data annually, as shown in supplementary figure s , which provides clear, concise information on annual rates. in this example, the rate of salmonellosis remains largely unchanging over time with distinct outbreaks seen in and . as expected, by compressing data to annual rates, supplementary figure s masks within-year trends of disease rates. foodnet reports and publications similarly tend to show only inter-annual changes in disease counts or rates [ ] [ ] [ ] [ ] [ ] , . without more granular within-year variations, the viewer cannot determine if increased yearly rates are driven by erratic outbreaks in a specific month or higher rates across all months of the year. to capture within-year trends, we propose a multi-panel plot that combines information on monthly rates, inter-annual trends, and the frequency distribution of rates by utilizing the shared axes of individual plots (fig. ) . the right panel of fig. provides a time series of monthly rates with a nbhr model fit with three trend terms (linear, quadratic, and cubic). the inclusion of polynomial terms allows us to capture long-term trends (linear term) and their acceleration and deceleration over time (quadratic and cubic terms). the predicted trend line is shown in blue and its % confidence interval is in grey shades. the estimated median monthly rate is shown in red. the left panel depicts a rotated histogram of rate frequencies indicating the right-skewness of the monthly rate distribution. the histogram shares the vertical monthly rate-axis with the time series plot and is essential for connecting two concepts: the distribution of monthly counts on the base of their frequency and the distribution of monthly counts over time. two pictograms refer to the selected pathogen and location. figure shows the stability of seasonal oscillation in salmonellosis over time series with increased rates from - followed by a gradual decrease in rates through . while preserving the within-year seasonal fluctuations, the plot provides additional information. alternating background colours help distinguish differences in the shape of seasonal curves between adjacent years. an increasingly darker hue for the monthly rate values distinguishes more recent data from more historic data. contrasting background colours mixed with a gradual intensity of line hues, saturation, brightness, and transparency allow for greater focus and attention to trends in the data [ ] [ ] [ ] . the rotated histogram in the left panel of fig. shows the distribution of monthly rates and its degree of skewness due to months with high counts. we include the red median line to provide the most appropriate measure of central tendency for the skewed distribution. the shared vertical axis helps readers track those high values to a www.nature.com/scientificdata www.nature.com/scientificdata/ specific month in the time series. the distribution also justifies the use of negative binomial regression models to evaluate temporal patterns. by supplementing the time series plot with the distribution of monthly rates, we show a visual rationale for using appropriate analytical tools (negative binomial model, in this case) for calculating inter-annual trends. to better understand annual differences in seasonal behaviors, we propose a multi-panel plot that incorporates annual seasonal signatures, summary statistics of monthly rates, and radar plots (fig. ). given varying visual perceptions of these three ways of presenting seasonal patterns, we offer side-by-side comparisons that aim to increase comprehension. the top-left panel provides an overlay of all annual seasonal signatures, a set of curves depicting characteristic variations in disease incidence over the course of one year, where line hues become increasingly darker with more recent data and a red line indicates median monthly rates, as in fig. . the bottom-left panel provides a set of box plots for each month that aggregates information over the study period and provides essential summary statistics, including the median rate values and the measures of spread. the shared horizontal axis allows the two plots to be compared across the years using identical scales. to provide visual context, background colours were used to indicate the four seasons (winter, spring, summer and autumn). the right panel provides overlaying monthly rates using a radar plot where time is indicated on the rotational axis and rates are indicated on the radial axis. the radar plot emphasizes the periodic nature of seasonal variations in one continuous line with graduating colours. the colour hue of the lines, background colour, median line colour and the axis scales are uniform across all three panels. we also repeat the pictograms to refer to the selected pathogen and location. for salmonellosis, disease rates are highest in the summertime (with peaks in july and august) and lowest during the wintertime (with a well-defined february nadir). rate increases and decreases during equinox periods indicate bacterial growth rates due to more and less favourable climate conditions, respectively. the www.nature.com/scientificdata www.nature.com/scientificdata/ confidence interval (whisker), and outliers or potentially influential observations (markers) over the -year period. measures of distribution spread provide an insight for the dispersion of rates in each month: the variability of salmonellosis rates decreases in winter months closer to the february nadir but increases in summer months of july and august closer to the seasonal peak. unusually high values are indicative of erratic behavior characterized by spikes in specific months and years. the right-hand panel of fig. further emphasizes the periodic nature and the positioning of the seasonal peaks and nadirs. radar or spider plots describe time using a rotational axis where the radial distance from the centre of the plot depicts rate magnitude [ ] [ ] [ ] [ ] . radial axes, compared to perpendicular axes, show annual fluctuations as a continuous flow. this more clearly demonstrates declines of salmonellosis rates during nadir months (november to march) without the visual discontinuity of left panel visuals. to capture the advantage of a multi-panel plot (fig. ) , we incorporate the boxplot from fig. (lower left panel) with a calendar heatmap containing monthly rate values. in the heatmap, information for each individual year is shown as stacked rows of width (for each month of the year) where cell colour intensity represents the magnitude of monthly rates. like fig. , the heatmap illustrates the highest rates (shown as the darker cells) are in july and august. compared to stacked line plots, however, fig. provides an individual row for each year of the time series, allowing for greater decomposition, differentiation, and comparison of seasonal signatures across years. in this plot, seasonal changes are shown horizontally from left to right -from january to december and the yearly trend transition can be observed in a vertical view from bottom to top-from year to in the right panel. while fig. provides the annual variability of seasonal patterns, monthly rate values for each year are difficult to ascertain. instead, the emphasis is placed on similarities and differences of the seasonal curvature over time. in fig. , the attention shifts to comparing the intensity of rates per month of the year across years. here, we evaluate which months of the year are most intense across years using the intensity of each cell's colour hue to describe the intensity of rates. the fig. panel integrates information on both trends and seasonality along with the individual monthly values unlike any of the previously shown visualizations. yearly rates provide a bar graph for comparing fluctuations in inter-annual rates while the adjacent heatmap indicates the month(s) driving these fluctuations. in doing so, the calendar heatmap identifies whether inter-annual changes are driven by sporadic outbreaks or increased seasonal magnitude of rates. at the same time, the shared axis box plot provides an overview of the average seasonal signature for the entire time series, as emphasized in fig. . understanding seasonal features. detailed characterization of the timing and intensity of seasonal peaks requires a standardized estimation of peak timing and amplitude. this standardization improves upon implemented techniques of comparing months with the highest cases in a given year by applying the δ-methods to www.nature.com/scientificdata www.nature.com/scientificdata/ nbhr model parameters , . average seasonality characteristics can be estimated across the full time series while annual estimates allow for more granular comparisons between years. to depict point estimates and confidence intervals of seasonality characteristics, we use forest plots -a technique commonly used in meta-analyses , , . we develop a multi-panel forest plot to depict annual peak timing, annual amplitude, and their joint distribution, to better understand the relationship among the seasonal features and how it changes over time (fig. ) . figure is a multi-panel plot that incorporates two forest plots (one each for annual peak timing and amplitude estimates) and one scatterplot (for peak timing and amplitude) to describe seasonality features. the top-left www.nature.com/scientificdata www.nature.com/scientificdata/ panel shows peak timing estimates (as month of the year, ranging from . (beginning of january) to . (end of december) -horizontal axis) for each study year (vertical axis). the bottom-right panel shows amplitude estimates where the horizontal axis indicates the study year and the vertical axis shows the amplitude (ratio between the disease rate at peak and the median rate). the bottom-left corner shows the scatterplot of peak timing (horizontal axis) and amplitude (vertical axis) with markers representing each pair of annual estimates. measures of uncertainty ( % confidence intervals) are reflected in error bars of each marker; dashed red lines show median peak timing and amplitude estimates. forest plots in fig. provide a compact, clear, and comprehensive visual describing the stability of peak timing and amplitude, even without showing the entire seasonal signature. for example, salmonellosis peak timing and amplitude vary little each year indicating strong, stable seasonal peaks in july and august. consistent peak timing means practitioners could time preventive strategies, increase awareness for foodborne illnesses to prevent transmission, and inform food retailers of when food safety inspections should be in higher demand within their supply chains. consistent amplitude estimates show that the intensity of salmonellosis varies little over time, suggesting that federal food safety regulations have not greatly influenced the number of salmonellosis cases annually. this type of information is likely to benefit foodnet fast users. supplementary figure s provides an example of how a sporadic outbreak behavior can be depicted by forest plots of peak timing and amplitude estimates for shigellosis in ny. the lack of seasonality for shigellosis is shown by the broad confidence intervals for peak timing, spanning the entire year and beyond. figure s provides an example bar chart showing differences in the average annual incidence of salmonellosis for the ten foodnet-surveyed states. as with other foodnet visualizations, data has been compressed to show only average annual estimates. like in fig. , annual rates mask within-year seasonal variations, calling into question if differences in states are driven by single year outbreaks. the alphabetical organization of the horizontal axis makes states ranking and comparison more difficult than if they were ordered from highest to lowest rates. to ease comparisons of a single disease across www.nature.com/scientificdata www.nature.com/scientificdata/ geographic locations, we generated two multi-panel plots (figs. and ). these plots mirror the same techniques shown above but include multiple shared axes and multiple locations to draw spatial comparisons. supplementary figure s follows the same design as fig. ; we replicate this design for salmonellosis in all foodnet-surveyed states. we present all states in one plot in a descending order by the sum of yearly rates in each state and display all available data so that state level patterns can be compared. the box plot in the top panel provides an overview of the seasonal signature for the entire us. the bottom panel disaggregates the entire us by states. as shown, all states share similar peak timing in july and august for almost every surveillance year from - . for some states, like ga and ca, rates are densely concentrated from july to september with rapid decline from september to february and gradual incline from february to july. for other states, like ny and or, seasonal peaks are much less pronounced and rate differences are smaller between months. clear indication of missing data provides additional information on differences in reporting completeness not captured by previous figures. while heatmaps provide information on seasonal signatures, yearly rate bar graphs (right panel) capture state-level trends over time. states are stacked in the order of total cases from - , showing differences in the intensity of salmonellosis infection across states. comparisons within states between years help identify inter-annual rate changes over time. for example, while md and ca have generally declined in annual rates over the -year period, ga rates increased from - and steadily declined from - . in combination with heatmaps, yearly rates also allow for detailed assessment of sporadic outbreaks. for example, erratic outbreaks came from two monthly spikes in april and june for ct in while for nm in a multi-month outbreak lasted from may to july. by using shared horizontal and vertical axes, this plot eases the comparison of disease rates across months, years and states. it also helps to determine hotspots and detect potential co-occurrences of infection in different states. moreover, the plot can be periodically updated by adding new information, offering a sustainable approach to make consistent comparisons between historical data and data captured in the future. to compare seasonality features across locations, we designed a multi-panel plot similar to fig. to show average peak timing and amplitude estimates over the -year period for each state. in fig. the top-left panel plots peak timing estimates ordered from the earliest (or) to latest (ga) peak timing while the bottom-right panel plots amplitude estimates in order of magnitude. marker and line colours are used to differentiate the seasonality feature estimate and its measure of uncertainty between states. the bottom-left panel shows the relationship between peak timing and amplitude across states. figure s provides an example of foodnet fast bar chart showing differences in the total confirmed infections for each of the nine surveyed pathogens in the us from - . the visual shows that infections due to campylobacter and salmonella have the highest cumulative counts of infections while cyclospora has the lowest counts. while depicting these differences clearly, this visual lacks sufficient specificity for drawing more intricate comparisons between infections. how are counts or rates distributed by year? what are the within-year variations of rates by pathogen? how do seasonal signatures and their variability differ by pathogen? can axes be reordered or recalculated for easier comparisons between pathogen counts or rates? we propose two multi-panel plots (figs. and ) that improve the comparisons of multiple diseases for a given geographic location. figure replicates the plot design of fig. but emphasizes comparisons between pathogens for a single location. instead of a seasonal signature box plot, the top panel provides a scatterplot to illustrate the peak timing and amplitude of each pathogen. in combination with the heatmap in the bottom panel, these plots illustrate the strong seasonality of salmonellosis, campylobacteriosis, and stec in july and august and cryptosporidiosis in august. these seasonal peaks are consistent across almost all years suggesting a stable seasonal periodicity and strong alignment between infections. in contrast, infections caused by yersinia enterocolitica, vibriosis, listeriosis, and cyclosporiasis have much less pronounced seasonality and monthly rates much lower than salmonellosis or campylobacteriosis. yearly rates, shown in the right panel, indicate erratic outbreak behaviors for cyclosporiasis. given sizable differences in rates across diseases we applied a high-order calibration colour scheme. we also provide the same multi-panel, shared-axis visualization design seen in fig. for comparisons across pathogens. figure includes a forest plot of peak timing by disease pathogen (top-left panel), a forest plot of amplitude by pathogen (bottom-right panel), and a scatterplot between peak timing and amplitude estimates (bottom-left panel). as in fig. , average peak timing and amplitude estimates are calculated using nbhr models for the entire -year time series. comparisons between diseases allow for understanding the alignment of seasonal processes across pathogens as well as shared relative magnitudes in a specific location. in our case, most of the pathogens peak during the summertime except cyclosporiasis. however, if the selected diseases peak during winter months, we recommend adjusting the starting and ending months to center these peaks in the figure. in this study we offered ways of thinking on how public data platforms can be improved by using visual analytics to provide a comprehensive description of trends and seasonality features in reported infectious diseases. we emphasize the utility of multi-panel graphs by showing side-by-side different methods of depicting trends over time and features of seasonality, including disease peak timing and amplitude. we provided visual tools to show trends (fig. ) , examine seasonal signatures (figs. and ) and their characteristics (fig. ) , compare diseases across locations for trends (fig. ) and seasonal signatures (fig. ) , and drawing comparisons across pathogens for trends (fig. ) and seasonal signatures (fig. ) . we also provide guides on how to explore and compare trends and seasonality between multiple diseases and geographic locations using foodnet fast data. given varying visual perceptions, we offer side-by-side comparison of different tools aiming to increase comprehension and faster adoption of efficient graphical depictions. www.nature.com/scientificdata www.nature.com/scientificdata/ we developed a time series of monthly rates by reconstructing a time series of monthly counts (see fig. ) then dividing counts by the sum of all foodnet-surveyed counties' mid-year populations per state per , , persons. in this calculation, we recognize that average monthly percentages are rounded in the raw data file and do not sum to % annually for downloaded years. this rounding resulted in obtaining non-integer counts within our time series. to prevent modification of raw data files, we did not round counts to integers before or after calculating rates. no information is provided on the foodnet fast website for the definition of confirmed cases, and data downloads provide no metadata for distinguishing cases from hospitalizations and deaths. although the case definition is provided on the cdc website as "laboratory-confirmed cases (defined as isolation for bacteria or identification for parasites of an organism from a clinical specimen) and cases diagnosed using culture-independent methods" , it forces the user to assume that a confirmed case is any person with laboratory confirmed cultures of a specific pathogen who may or may not have been hospitalized or died from infection. foodnet also collects information on hospitalizations and deaths, but does not provide information on the monthly percentage of hospitalizations or deaths, so users are unable to reconstruct a monthly time series for deaths or hospitalizations. the foodnet fast platform states all confirmed diseases as "incidence" calculations. technical documentation on the foodnet website shows that the term incidence reflects cases per , persons (used interchangeably with a disease rate) with no distinction of whether these are newly introduced within the population (i.e. incidence) or the total persons diagnosed with a disease (i.e. prevalence) . we found that monthly rates can similarly be calculated by multiplying annual incidence rates and the monthly percentage of confirmed cases for each disease-state pair. differences between our calculations and this alternative method are no more than ± %. we suspect that rounding errors of average monthly percentages and differential population catchment areas for rate calculations cause these differences. as shown in supplemental table s , population of the surveillance catchment area is changing over time. oftentimes, publicly available surveillance datasets, including foodnet fast, do not include location-and year-specific population catchment area estimates, which are needed for calculating rates from diseases counts. as foodnet does not provide population catchment areas for calculating rates, it www.nature.com/scientificdata www.nature.com/scientificdata/ www.nature.com/scientificdata www.nature.com/scientificdata/ forces the user to assume that foodnet surveillance reaches the total population of a surveyed county (likely an overestimate), yet such oversight is easy to fix. three collaborators confirmed our monthly rate calculations for quality control. we applied the negative binomial harmonic regression nbhr models, commonly used in the time series analysis of counts and cases. while the use of nbhr models, specifically the inclusion of trigonometric harmonic oscillations, is similar to existing works on foodborne illnesses, these studies often incorporate harmonic oscillators only to adjust for or remove seasonal oscillations [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] . we have extended the use of harmonic terms and develop the tools to estimate peak timing and amplitude , , . the developed δ-method provides a systematic calculation of confidence intervals for peak timing and amplitude estimates based on the results of harmonic regression models. in the proposed approach, we present the amplitude as the ratio of seasonal peak to seasonal median, which offers robust estimation even for rare or highly sporadic infections. these features are not available when traditional models, like auto-regressive integrated moving average (arima), are applied . measures of uncertainty enable formal testing and comparisons across diseases in the same location or locations for the same disease. in our previous works, we have demonstrated the broad utility of the δ-method and applications of peak timing and amplitude estimation in the context of epidemiological studies , , [ ] [ ] [ ] [ ] [ ] [ ] [ ] . we evaluate each state's cases individually as well as all national cases as the sum of all states' cases. our analysis evaluated all cases reported to foodnet fast irrespective of demographic factors such as age group, sex, or ethnic group. future analyses can consider conducting analyses using demographic factors available on the foodnet fast platform such as age group (< , - , - , - , - , - , - , - , + years), sex (male and female), and ethnic group (american indian and alaskan native, asian and pacific islander, black, multiple, white). to incorporate this information, our methodology for data extraction would need to be repeated for each subcategory or combination of categories desired (e.g. download files for males and files for females). www.nature.com/scientificdata www.nature.com/scientificdata/ future analyses can also consider differences in pathogen strain, which can only be obtained if extracting data for each pathogen-location-year combination (e.g. files for each of the diseases for each of locations or , files). foodnet fast, like many global disease surveillance databases, has no metadata describing missing data. foodnet fast reports missing counts using "n/a" for years when pathogens or locations were not under surveillance. however, there are also years when foodnet surveillance was live in a state, but a pathogen is missing from the data download. we believe that this missing data comes when, for a given year, a pathogen has total cases. however, we cannot specify whether absences of surveillance reporting came due to a breakdown in reporting or annual counts. without specification, we have set any year with "n/a" as missing due to no reported case information. when calculating peak timing and amplitude using the δ-methods, we applied nbhr models adjusted for harmonic seasonal oscillators and three trends (linear, quadratic, and cubic). we selected the polynomial terms as an example, yet researchers can consider alternative techniques for measuring seasonality such as splines, nonparametric regression, arima models, or their extensions. additionally, the cdc recommends using a mixed effects model when conducting time series analyses on foodnet fast data to account for differential population catchment areas and laboratory culture confirmation techniques pre-and post- , , . we focus on the analysis of individual states and diseases and adjust for population catchment variations by calculating monthly rates using county-level population estimates. future analyses could include detailed assessments between peak timing and amplitude across diseases, locations, and time periods. such analyses will help determine whether a synchronization of outbreak peaks occurs or if social, economic, or environmental factors influence peak timing and amplitude. future applications. this analecta of visualizations intends to communicate detailed information on foodborne outbreak trends and seasonality suitable for a general audience, public health professionals, stakeholders, and policymakers. future applications would involve the development of an interactive web-based platform allowing users to select the outcome, timeframe, and location of interest for educational training and research purposes. for example, public health researchers and practitioners could use this tool to generate insights related to long-term trends, changes in disease dynamics, or changes in populations at risk . information on when and where outbreaks are most common enable producers, distributors, and retailers to improve food safety practices to prevent these outbreaks. finally, this platform could aid policymakers in shaping public understanding of outbreak dynamics and using scientific evidence to refine public health policies. the analecta of our time series of monthly rates, data visualizations, and code used for all calculations and visualizations are available on our website (https://sites.tufts.edu/naumovalabs/analecta/). data and code can be directly downloaded from the website while visualizations are linked on the website to an external visualization repository. time series data and code are also available on figshare . visualizations on our website are provided in the same order as presented here: describing trends (fig. ) , examining seasonal signatures with the three standard techniques: line graphs, boxplots, and radar plots (fig. ) and heatmaps (fig. ) , characterizing features of seasonality (fig. ) , drawing comparisons across locations for trends (fig. ) and seasonal signatures (fig. ) , and drawing comparisons across pathogens for trends (fig. ) and seasonal signatures (fig. ) . file downloads are available for trend, seasonal signature, and annual time series visualizations. for images examining a single disease in a single location, downloads are formatted where the prefix abbreviates the location and the suffix abbreviates the pathogen (see supplementary table s ). for visualizations comparing multiple locations or diseases, the prefix "loc" indicates comparisons across locations while the prefix "dis" indicates comparisons across pathogens (see supplementary tables s ,s ). all statistical analyses were conducted using stata (se . ) software. all visualizations were created using r version . . and tableau professional . software. all software code is open access on our website (https:// sites.tufts.edu/naumovalabs/analecta/) and figshare, and is available for public reuse with proper citation of this manuscript . web-based infectious disease surveillance systems and public health perspectives: a systematic review detecting influenza epidemics using search engine query data innovation in observation: a vision for early outbreak detection use of unstructured event-based reports for global infectious disease surveillance algorithms for rapid outbreak detection: a research synthesis influenza seasonality: underlying causes and modeling theories flunet. global influenza surveillance and response systems (gisrs) visual analytics for epidemiologists: understanding the interactions between age, time, and disease with multi-panel graphs incidence and trends of disease with pathogens transmitted commonly through food -foodborne diseases active surveillance network preliminary incidence and trends 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petting zoo animals for use in exposure assessments global prevalence of asymptomatic norovirus disease: a meta-analysis foodnet fast: pathogen surveillance tool faq assessing the impact of environmental exposures and cryptosporidium disease in cattle on human incidence of cryptosporidiosis in southwestern ontario do contamination of and exposure to chicken meat and water drive the temporal dynamics of campylobacter cases? review of epidemiological studies of drinking-water turbidity in relation to acute gastrointestinal illness seasonality and the effects of weather on camylobacter diseases increase in reported cholera cases in haiti following hurricane matthew: an interrupted time series model complex temporal climate signals drive the emergence of human water-borne disease association between community socioeconomic factors, animal feeding operations, and campylobacteriosis incidence rates: foodborne diseases active surveillance network (foodnet) climate, human behaviour or environment: individual-based modelling of campylobacter seasonality and strategies to reduce disease burden temperature-driven campylobacter seasonality in england and wales rotavirus seasonality: an application of singular spectrum analysis and polyharmonic modeling mystery of seasonality: getting the rhythm of nature seasonal synchronization of influenza in the united states older adult population geographic variations and temporal trends of salmonella-associated hospitalization in the u.s. elderly, - : a time series analysis of the impact of haccp regulation hospitalization of the elderly in the united states for nonspecific gastrointestinal diseases: a search for etiological clues assessing seasonality variation with harmonic regression: accommodations for sharp peaks intelligence advanced research projects activity (iarpa), via - . the views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of odni, iarpa, or the u.s. government. the u.s. government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright annotation therein. the research was in part supported by the national science foundation (nsf) innovations in graduate education (ige) program, via grant award and by the united states department of agriculture (usda) national institute of food and agriculture (nifa) cooperative state research, education, and extension service fellowship meghan hartwick for editorial and technical assistance r.s. contributed to data extraction, formal analysis, and writing. b.z. contributed to data validation, conceptualization of visual aids, and visualization creation. t.m.a.f. contributed to data validation, review, and editing. e.n.n. contributed to methodology development, review and editing, supervision, project administration and funding acquisition. the authors declare no competing interests. supplementary information is available for this paper at https://doi.org/ . /s - - -x.correspondence and requests for materials should be addressed to e.n.n.reprints and permissions information is available at www.nature.com/reprints.publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. license, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the creative commons license, and indicate if changes were made. the images or other third party material in this article are included in the article's creative commons license, unless indicated otherwise in a credit line to the material. if material is not included in the article's creative commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. to view a copy of this license, visit http://creativecommons.org/licenses/by/ . /. key: cord- -kbnz sy authors: zhao, x.; tatapudi, h. a.; corey, g.; gopalappa, c. title: threshold analyses on rates of testing, transmission, and contact for covid- control in a university setting date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: kbnz sy we simulated epidemic projections of a potential covid- outbreak in a university population of , persons, under varying combinations of mass test rate ( % to %), contact trace and test rate ( % to %), transmission rate (probability of transmission per contact per day), and contact rate (number of contacts per person per day). we simulated four levels of transmission rate, % (average baseline), % (average for face mask use), . % (average for ft distancing), and . % (average for ft distancing and face mask use), interpolating results to the full range to understand the impact of uncertainty in effectiveness, feasibility, and adherence of face mask use and physical distancing. we evaluated contact rates between and , to identify the threshold that, if exceeded, could lead to several deaths. when transmission rate was %, for trace and test at %, the contact rate threshold was . however, any time delays in trace, test, and isolation quickly raised the number of deaths. keeping contact rate to or below was more robust to testing delays, keeping deaths below up to a delay of days from the time of infection to diagnosis and isolation. for a contact rate of , the number of trace and tests peaked to about per day and relaxed to with the addition of % mass test. when transmission rate was . %, for trace and test at %, the contact rate threshold was . however, keeping contact rate to or below was more robust to delays in testing, keeping deaths below up to a delay of days from the time of infection to diagnosis and isolation. for contact rate of , the number of trace and tests peaked at per day and relaxed to per day with the addition of % mass test. threshold estimates can help develop on-campus scheduling and indoor-spacing plans in conjunction with plans for asymptomatic testing for covid- . combination thresholds should be selected specific to the setting based on an assessment of the feasibility and resource availability for testing and quarantine. the covid- pandemic caused by the sars-cov- virus has caused significant disease and economic burdens since its first outbreak in december . in the absence of an effective vaccine, the main intervention for the prevention of covid- transmissions has been social distancing. the most effective social distancing being lockdowns of non-essential organizations and services, as adopted by several states since march, , in efforts to immediately slow down the pandemic [ ] . however, lockdowns are a huge threat to the economic stability of a nation as seen by the unprecedented rise in unemployment rates [ ] [ ] . therefore, while lockdowns are a good short-term strategy, for a long-term strategy or until a vaccine becomes widely available, it has become necessary to identify alternate strategies and lifestyles that control the disease burden while minimizing the economic burden. interventions that are effective include the use of face masks, physical distancing between persons at a recommended ft, and contact tracing and testing or mass testing to enable early diagnosis in the asymptomatic stage of infection [ ] . however, removal of lockdowns should be strictly accompanied by a reopening plan that rapidly and efficiently enables the adoption of the above interventions, to avoid an epidemic rebound. in addition to public health agencies, all members of a community, in both public and private sectors, play a key role in the development and implementation of a reopening plan that is most suited for their organization [ ] . among these sectors, universities and colleges bear a special burden to develop a reopening plan that include changes to a range of activities related to teaching, research, dining, housing, and extra-curricular activities [ ] . we developed a compartmental differential equations model to simulate epidemic projections of a potential covid- outbreak in a population of , individuals representative of undergraduate and graduate students, faculty and staff in a residential university in the united states. we simulated epidemic projections, of potential outbreaks, under varying combinations of contact tracing and testing and mass testing, to identify combinations that would reduce the effective reproduction number to a value below the epidemic threshold of . is directly proportional to the duration of infectiousness, transmission rate (the probability of transmission per contact per day, representing the infectiousness of the virus), and contact rate (the number of contacts per person per day) [ ] . trace and test and universal mass test lead to early diagnosis in the asymptomatic phase of the infection and, if persons diagnosed with infection are successfully quarantined, they reduce the duration of exposed infectiousness [ ] [ ] [ ] and thus reduce . physical distancing by the recommended ft and use of face masks can reduce transmission rate, and thus reduce [ ] [ ] . reducing contact rate directly reduces , however, the expected contact rates are dependent on the planned facility layout and scheduling of classrooms, housing, dining, research labs, and offices. while covid- simulation models have typically used a product of transmission rate and contact rate as one metric, we evaluate these separately, as it could help inform scheduling and facility layout decisions. while physical distancing by the recommended ft and use of face masks can reduce transmission rate, there is considerable uncertainty in the expected reduction, with studies showing that it is likely to be less than % even if used properly [ ] [ ] [ ] [ ] . that is, a person who is at a six feet distance is also a contact for potential transmission, although the transmission rate (per contact) would be low. therefore, if not properly planned, the movement of students between multiple indoor locations, such as shared student housing or dorms, classrooms, dining halls, and shared research lab and office spaces, could create a high contact rate, even in the absence of large social gatherings. this can be further exacerbated by the ease of transmission of the virus. while it is known that indoor gatherings such as events, bars, and restaurants have contributed to a significant portion of the cases [ studies that have examined the impact of school closures and stay at home policies. in the past, some of these studies examined the impact of policies during the h n pandemic [ ] [ ] . however, these studies targeted closure of schools or several classes in a school for certain periods of time and do not explore partial re-opening or closure [ ] [ ] [ ] . in more recent times, a johns hopkins study provided an ethical framework for the covid- reopening process [ ] . this framework is intended for policy makers on the state level to develop plans for reopening of their state. in the framework, they highlight the long-term closure of schools can have a detrimental effect on children but warns policy makers to not shy away from re-imposing social distancing measures if hospitalizations or cases cross over a benchmark. a literature review on school closure policies states that policy makers need to strongly consider combinations of social distancing policies when planning to reopen [ ] . one study examined the impact of social distancing, contact tracing and household quarantine in a boston metropolitan area [ ] . they tested the effectiveness of these policies to avoid a second wave of the pandemic using a granular agent-based model. in our search, we found only one study that researched the impact of school closure policies during the covid- pandemic for k- schools [ ] . in this study, the authors study the impact of partial, complete and progressive reopening of schools. they also study social distancing interventions, testing, and isolation, and estimate hospital bed capacity needs if schools were to be reopened. while it is generally known that increasing contact tracing and testing is necessary, studies directly observing the number of tests needed at an organizational level, such as university, are . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint only recently emerging. one study analyzing combination interventions, in generalized populations, that include contact tracing estimated that reducing of . to an of requires more than % of contact tracing [ ] . for an of . , at least % of contact tracing and for an of . , more than % of contact tracing. a modeling study applied to the boston area [ ] should not be used as a metric for selection of a strategy. selection of a scenario should be done after a feasibility assessment. the estimates for number of tests and quarantines, along with the uncertainty in the transmission rates, under each scenario, could help in the feasibility assessment, based on the resource needs such as personnel, equipment, and infrastructure, and . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . simulation methodology we developed a compartmental model for simulating epidemic projections overtime. the epidemic flow diagram is depicted in figure . each box is an epidemic state, and each arrow represents a transition from one state to another. note, each compartment is further split by age and gender, but for clarity of notations, we do not include it in the equations below. cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint use the proportion hospitalized as a proxy for severe cases; the denominator is based on the assumption that the duration of exposed phase is equal to the difference between the duration of the incubation period and the latent period. never show symptoms and thus directly go from exposed to recovered. , which assumes that person with mild cases that did not get diagnosed through symptom-based testing have a chance of getting tested through additional testing options, and self-quarantine upon diagnosis. , theoretically, , should be the same as , , however, as the rate of transitioning from to is fixed to proportion hospitalized under symptom-based tests, if extensive testing is conducted, the number of . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . we simulate the epidemic over time using the following system of differential equations where, = a matrix of transition rates between states (arrows in figure ), and = time-step. we use a time-unit of per day for the transition rates in and set = , and thus, the model simulates every th of a day. the expansion of the system of differential equations are as follows: cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint we can further expand by substitution of the rate terms with their equations as follows: . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . input data assumptions and sources for simulation model we used natural disease progression estimates from other studies in the literature. the description of the data, sources, and values (with ranges and medians where applicable) for all parameters are available in the supplemental appendix. briefly, we assumed an incubation period duration of . days [ ] , the first . days in stage l (not infectious and asymptomatic) [ ] , and the remaining in stage e (infectious and asymptomatic). we assumed about % of cases develop medium to severe symptoms [ ] [ ] [ ] and, in the absence of test and trace or mass test, can be diagnosed through symptom-based testing. we assumed the remaining % of cases show mild to no symptoms and can be diagnosed only through trace and test, or universal . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint mass test. we assumed an average duration of . days from the time of onset of symptoms to hospitalization [ ] , with the proportion hospitalized varying as a function of age. for mild cases, we assumed an average duration of days from the time of onset of symptoms to recovery [ ] . we assumed case fatality rates vary as a function of age and gender. interventions we evaluated mass testing at % and % of the population. we assumed a maximum contact tracing rate of %, modeling the rate as the inverse of the time to find, test, and isolate infected contacts from the time of their infection. to test the sensitivity of delays associated with trace and/or test, we evaluated trace and test rates of %, %, %, %, %, and %, equivalent of , , , , , and days, respectively, from time of infection to effective isolation. we assumed trace and test would initiate within the first cases of diagnosis. to test the sensitivity of delays in initiation of trace and test, we also evaluated scenarios by delaying the initiating of trace and test to after diagnoses of cases. we evaluated transmission rates ( ) of % (baseline), % (mid), . % (lower-mid), and . % (lowest). the baseline value of corresponds to an average estimate under no physical distancing and no face masks [ ] [ ] . transmission rate of % relative to baseline corresponds to expected relative risk under use of face masks in non-health care settings [ ] . transmission rates of . % and . % correspond to expected rates under ft and ft physical distancing, respectively [ ] . we evaluated contact rates between and ( ), we did not separate between on-campus and off-campus contact rates. in all scenarios, we applied baseline symptom-based testing and -day quarantine for diagnosed persons. for diagnosis in asymptomatic stages, we assumed a test sensitivity of . for trace and test and universal (mass) testing [ ] . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . massachusetts amherst, amherst, ma, to determine the population size of undergraduate and graduate students and their age and gender distributions [ ] . for faculty and staff, we used the age distribution of persons years and older from the town of amherst, ma, where the university is located [ ] . to initiate an outbreak, we assumed to infected cases on day based on the following. we assumed that the proportion of incoming students who are infected would be equal to the prevalence of massachusetts. we also assumed that all incoming students would be tested, and about % of infected cases would be false negatives. prevalence is unknown, as not all cases are diagnosed and diagnosed cases are not specifically tracked. is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint the contact rate thresholds, which represent the values that, if exceeded, lead to greater than death, under varying combinations of transmission rate, trace and test, and universal test are presented in figure . initiating trace and test to after diagnoses of cases, and trace and test rates of % and lower (equivalent to more than days to find and isolate infected contacts from the time of their infection) reduced the contact rate threshold to ( figure d ). with maximum testing of % mass test, % trace and test, and initiating trace and test within cases of diagnoses, the threshold contact rate was (figure a) . when transmission rate was %, with only symptom-based test, only % mass test, or only % trace and test, the contact rate thresholds were , , and , respectively (figure a ). with both % mass test and % trace and test, the contact rate threshold was (figure a ). with % (and %) trace and test, equivalent to (and ) days to find and isolate infected contacts from the time of their infection, the contact rate threshold was (and ) ( figure b ). delays in . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint initiating trace and test to after diagnoses of cases, and trace and test rates of % and lower (equivalent to more than days to find and isolate contacts from the time of their infection), reduced the contact rate threshold to between and ( figure d ). when transmission rate was . %, with only symptom-based testing, only % mass test, or only % trace and test, the contact rate threshold were , , and , respectively (figure a ). with both % mass test and % trace and test, the contact rate threshold was (figure a ). with % (and %) trace and test, equivalent to (and ) days to find and isolate infected contacts from the time of their infection, the contact rate threshold was (and ) ( figure b ). delays in initiating trace and test to after diagnoses of cases, and trace and test rates of % and lower (equivalent to more than days to find and isolate contacts from the time of their infection), reduced the contact rate thresholds to between and ( figure d ). when transmission rate was . %, with only symptom-based test, or only % mass test, the threshold contact rates were , and , respectively ( figure a ). with % trace and test the epidemic was under control up until a contact rate of . delays in initiating trace and test to after diagnoses of cases, and trace and test rates of % and lower (equivalent to more than days to find and isolate contacts from the time of their infection), reduced the contact rate threshold to between and ( figure d ). the number of deaths under varying combinations of universal mass test, trace and test, transmission rate, and contact rate are presented in figures s and s of the appendix. all scenarios with less than death are also presented in the appendix figures s and s . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint for all scenarios with % trace and test that resulted in less than death, figure presents the total number of trace and tests over the duration of the semester, the peak number of trace and tests per day, and the peak number quarantined (excluding false positives), interpolated over the transmission rate range. both metrics increased as contact rate increased, and decreased with the addition of universal testing, as expected. when contact rate was reaching and when contact rate was and , respectively, and transmission rate was %. delay in initiating trace and test to after diagnosis of cases, would increase the peak number of trace and tests or increase deaths (figure ). when contact rate was and the transmission rate was below . %, total trace and tests varied from about ( % trace and test + % mass test) to ( % trace and test), and the peak trace and tests per day varied from about ( % trace and test + % mass test) to ( % trace and test). for combinations of transmission rate above . % and contact rate above , the number of trace and tests per day peak above and rise rapidly, e.g., reaching and ( % trace and test) when contact rate was and , respectively, and transmission rate was % (not shown in figure) . these two scenarios also generated deaths. adding % mass test reduces deaths to below , while also relaxing the peak trace and tests to and when contact rate was and , respectively. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint for scenarios with % trace and test, transmission rate below . %, and contact rate at or below, the peak quarantines per day (excluding false positives), went up to if trace and test initiated within diagnosis of cases (figure ) , and up to if delay in initiating trace and test to after diagnosis of cases (figure ) . as test specificity ranges from . % and % [ ] test, and delays in trace and test initiation) that meet the contact rate thresholds. when transmission rate was %, about % of scenarios had contact rate threshold of or higher, and when transmission rate was . %, about % of scenarios had contact rate threshold of or higher. specifically, when transmission rate was %, a contact rate of kept deaths below if trace and test rates were % or above (equivalent to finding and isolating infected contacts within days from the time of their infection), even with a delay in initiating trace and test to after diagnosis of cases (appendix figures s and s ). when transmission rate was . %, a contact rate of kept deaths below if trace and test rates were % or above (equivalent to . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint finding and isolating infected contacts within days from the time of their infection), even with a delay in initiating trace and test to after diagnosis of cases (appendix figures s and s ) . in these scenarios, the number of trace and tests peaked to between and when contact rate was and transmission rate was %, and to between and when contact rate was and transmission rate was . % (appendix figures s and s ) . it is difficult to determine how the threshold contact rate estimates compare to those expected at a university, as the data on contact rates prior to the covid- outbreak are unavailable. one study, conducted prior to the covid- outbreak, estimated an average rate of among middle-aged adults in portland, oregon [ ] , however, contact rates in a university are likely to be different. after the covid- outbreak, more studies to estimate contact rates are emerging, however, they are under the context of state-issued stay-at-home orders, and thus are representative of the lower bounds. in one such poll [ ] of u.s. adults, those who self-asses . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint their status as 'completely isolated' (about %) reported a median (and mean) non-household contact rate of (and . ), those who self-asses their status as 'mostly isolated' (about %), reported a median (and mean) non-household contact rate of (and . ), and those who self- asses their status as 'partially isolated' (about %), reported a median and mean non-household contact rate of (and . ). among those listing their work sector as 'education' (which included library and training services), reported a median (and mean) work contact rate of (and . ). another study [ ] reported a median (and mean) contact rate of (and . ) among a nationally representative survey of the us population, with % of surveyors reporting four or fewer contacts. the above studies were under maximum lockdowns, and thus, how these would change upon reopening, and specifically at a university, are unknown, but can be expected to be higher thus requiring careful control. is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint given the above challenges, in this study we attempted to separate out contact rates from transmission rates. considering the uncertainty in the baseline transmission rate, and in the expected reductions from face mask use and physical distancing [ ] , uncertainties rising from inherent features, feasibility, and compliance, we interpolated results for the full range of transmission rate. the transmission rates simulated here cover the range of estimates from the literature for baseline % ( . %- %), and expected reductions from use of surgical or cloth face masks in non-health care settings . % ( . %- . %), ft physical distancing . % ( . %- %), and ft physical distancing . %( . %- . %), calculated using relative risks from a meta- analysis study that, in addition to sars-cov- , evaluated viruses of similarly high virulence [ ] (see supplemental appendix table s ). the contact rate thresholds in this study can help inform decisions related to planning of indoor spacing and personnel scheduling, by eliminating scenarios that generate contact rates that cross the threshold. however, the selection of contact rates should be considered in conjunction with testing rates and transmission rates. the contact rate thresholds were low when trace and test rates were low or transmission rates were higher than . %. though the contact rate thresholds under low transmission rates and % trace and test were higher, going above , the feasibility of finding, testing, and isolating infected contacts within days of infection ( % trace and test) should be evaluated specific to the setting of implementation. when transmission rate was . % or below and contact rate was higher than , any delays in trace and test generated rapid accumulation of the number of persons to trace and test with the peak numbers per day going above , and eventually leading to several deaths if testing delays continued. when transmission rate was . %, a contact rate threshold of was more robust to testing delays, and . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . our work is subject to limitations. our model is deterministic. we did not specifically model false positives hence, the estimates here only provide a lower bound. we used an average contact rate for all persons, in order to help decisions related to designing a controlled environment, such as controlling workplace scheduling and layouts and issuing uniform guidelines. we did not model contact rates to be representative of actual expected behaviors of individuals or to be representative of actual expected networks between individuals. we did not explicitly model other interventions that could reduce transmission rate such as controlled ventilation, filtering air and controlling air flow, which are likely to impact transmissions [ ] . the transmission rates evaluated should be used with caution. the baseline estimate of % is an average estimate, and the estimates for face masks and physical distancing are relative to these estimates. for a different baseline transmission rate, the interpolated values of transmission rates should be used to determine expected reduction. we did not model other flu like illnesses and thus we did not . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted july , . indoor spacing and personnel scheduling scenarios that exceed these contact rate thresholds that have a high chance of an epidemic. the threshold contact rates can only help in elimination of strategies and should not be used as a metric for selection of a strategy. the uncertainty ranges in results suggest that selection of a strategy should collectively consider indoor spacing, personnel scheduling, testing, and quarantining. selection of a scenario should be done after a feasibility assessment that compares resource needs under each scenario to excepted resource availability for testing and quarantining, and risk assessment to determine the ability to control transmission rate through use of face masks and physical distancing, including its feasibility and compliance. acknowledgements we would like to acknowledge sonza singh, shifali bansal, seyedeh nazanin khatami, and arman mohseni kabir for their assistance in data collection in initial stages of the study, and dr. laura balzer, dr. michael ash, and dr. hari balasubramanian for their comments and inputs. . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . and trace and test (t), that generated less than deaths; s: symptom-based testing; %u, and %u: mass test rate per day, equivalent to test once every days, and days, respectively; %t, %t, %t, %t, %t, %t: %trace and test rate, representing days, days, days, days, days, and days, respectively, from the time of infection to diagnosis and isolation; transmission rates from the literature (see supplement appendix table s ) for baseline: % ( . %- %), surgical or cloth face masks use in non-health care setting . % ( . %- . %), ft physical distancing . % ( . %- %), and ft physical distancing . %( . %- . %). solid markers are simulated cases. dotted lines are interpolations . . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint figure : resource needs under varying combinations of mass test, trace and test ( %), contact rate, and transmission rate that generated less than deaths, when trace and test was initiated within cases of diagnoses. solid markers are simulated. dotted lines are interpolations. figure : resource needs under varying combinations of mass test, trace and test ( %), contact rate, and transmission rate that generated less than deaths, when trace and test was initiated after diagnoses of cases. solid markers are simulated cases. dotted lines are interpolations. figure : among all the testing scenarios evaluated (varying levels of mass test, trace and test, and delays in trace and test initiation), the proportion of scenarios (y-axis) with contact rate threshold higher than the value on the x-axis. (e.g., for transmission rate (p) = %, about % of scenarios had contact rate threshold of or higher, and for p= . %, about % of scenarios had contact rate threshold of or higher). . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted july , . . https://doi.org/ . / . . . doi: medrxiv preprint timeline of covid- policies, cases, and deaths in your state the covid- crisis: how do u.s. employment and health outcomes compare to other oecd countries? unemployment in the time of covid- : a research agenda how to protect yourself & others interim guidance for businesses and employers responding to coronavirus disease (covid- ) interim guidance for administrators of us institutions of higher education epidemic theory (effective & basic reproduction numbers, epidemic thresholds) & techniques for analysis of infectious disease data (construction & use of epidemic curves, generation numbers, exceptional reporting & identification of significant clusters) effectiveness of isolation, testing, contact tracing, and physical distancing on reducing transmission of sars-cov- in different settings: a mathematical modelling study temporal dynamics in viral shedding and transmissibility of covid- covid- : towards controlling of a pandemic a rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients physical distancing, face masks, and eye protection to prevent person-to-person transmission of sars-cov- and covid- : a systematic review and meta-analysis masks plus hand hygiene reduced ili in college dorm study mask use, hand hygiene, and seasonal influenza-like illness among young adults: a randomized intervention trial droplets and aerosols in the transmission of sars-cov- how superspreading is fueling the pandemic -and how we can stop it airborne transmission route of covid- : why meters/ feet of inter-personal distance could not be enough experts with one big claim: the coronavirus is airborne transmission of covid- virus by droplets and aerosols: a critical review on the unresolved dichotomy consideration of the aerosol transmission for covid- and public health reducing transmission of sars-cov- identifying airborne transmission as the dominant route for the spread of covid- guidelines -opening up american again white house releases 'opening up america again' guidelines would school closure for the h n influenza epidemic have been worth the cost?: a computational simulation of pennsylvania closure of schools during an influenza pandemic simulating school closure policies for cost effective pandemic decision making an ethics framework for the covid- reopening process school closure and management practices during coronavirus outbreaks including covid- : a rapid systematic review modeling the impact of social distancing, testing, contact tracing and household quarantine on second-wave scenarios of the covid- epidemic expected impact of reopening schools after lockdown on covid- epidemic in Île-de-france feasibility of controlling covid- outbreaks by isolation of cases and contacts simulating covid- in a university environment covid- screening strategies that permit the safe re-opening of college campuses covid- on campus: how should schools be redesigned? what covid- computer models are telling colleges about the fall modeling covid- spread vs healthcare capacity epidemiological parameters of coronavirus disease : a pooled analysis of publicly reported individual data of cases from seven countries characteristics of and important lessons from the coronavirus disease (covid- ) outbreak in china summary of a report of cases from the chinese center for disease control and prevention substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (covid- )," medrxiv midas novel coronavirus repository a social network model of the covid- pandemic johns hopkins bloomberg school of public health at a glance profile of general population and housing characteristics: more information census summary file mixing patterns between age groups in social networks americans' social contacts during the covid- pandemic quantifying interpersonal contact in the united states during the spread of covid- : first results from the berkeley interpersonal contact study rapid expert consultation on the possibility of bioaerosol spread of sars cov- for the covid- pandemic aerosol and surface distribution of severe acute respiratory syndrome coronavirus in hospital wards aerodynamic analysis of sars-cov- in two wuhan hospitals aerosol and surface stability of sars-cov- as compared with sars-cov- association of infectied probability of covid- with ventilation rates in confined spaces: a wells-riley equation based investigation key: cord- -h kc w authors: liang, donghai; shi, liuhua; zhao, jingxuan; liu, pengfei; sarnat, jeremy a.; gao, song; schwartz, joel; liu, yang; ebelt, stefanie t.; scovronick, noah; chang, howard h. title: urban air pollution may enhance covid- case-fatality and mortality rates in the united states date: - - journal: innovation (n y) doi: . /j.xinn. . sha: doc_id: cord_uid: h kc w background the novel human coronavirus disease (covid- ) pandemic has claimed more than , lives worldwide, causing tremendous public health, social, and economic damages. while the risk factors of covid- are still under investigation, environmental factors, such as urban air pollution, may play an important role in increasing population susceptibility to covid- pathogenesis. methods we conducted a cross-sectional nationwide study using zero-inflated negative binomial models to estimate the association between long-term ( - ) county-level exposures to no , pm . and o and county-level covid- case-fatality and mortality rates in the us. we used both single and multipollutant models and controlled for spatial trends and a comprehensive set of potential confounders, including state-level test positive rate, county-level healthcare capacity, phase-of-epidemic, population mobility, population density, sociodemographics, socioeconomic status, race and ethnicity, behavioral risk factors, and meteorology. results , , covid- cases and , deaths were reported in , us counties from january , to july , , with an overall observed case-fatality rate of . %. county-level average no concentrations were positively associated with both covid- case-fatality rate and mortality rate in single-, bi-, and tri-pollutant models. when adjusted for co-pollutants, per inter-quartile range (iqr) increase in no ( . ppb), covid- case-fatality rate and mortality rate were associated with an increase of . % ( % ci . % to . %) and . % ( % ci . % to . %), respectively. we did not observe significant associations between covid- case-fatality rate and long-term exposure to pm . or o , although per iqr increase in pm . ( . ug/m ) was marginally associated with . % ( % ci: . % to . %) increase in covid- mortality rate when adjusted for co-pollutants. discussion long-term exposure to no , which largely arises from urban combustion sources such as traffic, may enhance susceptibility to severe covid- outcomes, independent of long-term pm . and o exposure. the results support targeted public health actions to protect residents from covid- in heavily polluted regions with historically high no levels. continuation of current efforts to lower traffic emissions and ambient air pollution may be an important component of reducing population-level risk of covid- case-fatality and mortality. the novel human coronavirus disease (covid- ) is an emerging infectious disease caused by severe acute respiratory syndrome coronavirus (sars-cov- ) . first identified in in wuhan, the capital of hubei province, china, the covid- pandemic has since rapidly spread throughout the world. as of july , , there have been , , cases and , deaths confirmed in the united states [ ] [ ] [ ] . despite substantial public health efforts, the observed covid- case-fatality rate (i.e. the ratio of the number of covid- deaths over the number of cases) in the us is estimated to be . % [ ] [ ] [ ] . although knowledge concerning the etiology of covid- -related disease has grown since the outbreak was first identified, there is still considerable uncertainty concerning its pathogenesis, as well as factors contributing to heterogeneity in disease severity around the globe. environmental factors [ ] [ ] [ ] [ ] , such as urban air pollution, may play an important role in increasing susceptibility to severe outcomes of covid- . the impact of ambient air pollution on excess morbidity and mortality has been well-established over several decades [ ] [ ] [ ] . in particular, major ubiquitous ambient air pollutants, including fine particulate matter (pm . ), nitrogen dioxide (no ), and ozone (o ), may have both a direct and indirect systemic impact on the human body by enhancing oxidative stress, inflammation, and respiratory infection risk, eventually leading to respiratory, cardiovascular, and immune system dysfunction and deterioration [ ] [ ] [ ] [ ] [ ] . while the epidemiologic evidence is limited, previous findings on the outbreak of severe acute respiratory syndrome (sars), the most closely related human coronavirus disease to covid- , revealed a crude positive correlation between air pollution and the sars case-fatality rate in the chinese population without adjustment for confounders . an analysis of cities in china recently demonstrated that temporal increases in covid- cases were associated with short-term variations in ambient air pollution . hence, it is plausible that prolonged exposure to air pollution may have a detrimental effect on the prognosis of patients affected by covid- . as is usual in the early literature on emerging hazards, questions remain concerning the generalizability and reproducibility of these finding, due to the lack of control for the epidemic stage-of-disease, population mobility, residual spatial correlation, and potential confounding by co-pollutants. to address these analytical gaps and contribute towards a more complete understanding of the impact of long-term exposures to ambient air pollution on covid- -related health consequences, we conducted a nationwide study in the usa ( , counties) examining associations between multiple key ambient air pollutants, no , pm . , and o , and covid- case-fatality and mortality rates in both single and multi-pollutant models, with j o u r n a l p r e -p r o o f comprehensive covariate adjustment. we hypothesized that residents living in counties with higher long-term ambient air pollution levels may be more susceptible to covid- severe outcomes, thus resulting in higher covid- case-fatality rates and mortality rates. we obtained the number of daily county-level covid- confirmed cases and deaths that occurred from january , , the day of first confirmed case in the us, through july , in the us from three databases: the new york times , usafacts , and point acres.com . briefly, data on county-level covid- cases and deaths data was confirmed by referencing state and local health agencies directly. covid- confirmed case counts include both laboratory confirmed cases and presumptive positive cases (i.e. cases diagnosed by doctors based on signs and symptoms without a test), which is in line with how the us center for disease control (cdc) reports data. in these databases, cases were assigned to where the person was diagnosed as that information became available. if a state reports both location of death and the location of residency, the case was attributed to the location of residency . covid- death counts include both confirmed (i.e. by meeting confirmatory laboratory evidence for covid - ) and probable deaths (i.e. meeting clinical criteria and epidemiologic evidence with no confirmatory laboratory testing performed for covid- ; meeting presumptive laboratory evidence and either clinical criteria or epidemiologic evidence; meeting vital records criteria with no confirmatory laboratory testing performed for covid ). after data acquisition from these sources, we compared the number of confirmed covid- cases and deaths in each us county (identified by the federal information processing standards, fips code) across all databases for accuracy and consistency. in case of discrepancy, county-level case and death number were corrected by manually checking the data reported from the corresponding state and local health department websites. in this analysis, the main covid- death outcomes included two measures, the county-level covid- case-fatality rate and mortality rate. the covid- case-fatality rate was calculated by dividing the number of deaths over the number of people diagnosed in each us county with at least confirmed case, which can imply the biological susceptibility towards severe covid- outcomes (i.e. death). the covid- mortality rate was the number of covid- deaths per million population, and can reflect the severity of the covid- outcomes in the general population. j o u r n a l p r e -p r o o f three major criteria ambient air pollutants were included in the analysis, including no , a traffic-related air pollutant and a major component of urban smog, pm . , a heterogeneous mixture of fine particles in the air, and o , a common secondary air pollutant . we recently estimated daily ambient no , pm . , and o levels at km spatial resolution across the contiguous us using an ensemble machine learning model - . we calculated the daily average for each county based on all covered km grid cells (i.e., we calculated the arithmetic mean of daily air pollutant concentrations at km grid cells whose centroids fall within the boundary of that county). we then further calculated the annual mean ( - ) for no and pm . , and the warm-season mean ( - ) for o , defined as may to october , which is a standard time window to examine the association between ozone and mortality . although more recent exposure data were not available, county-specific mean concentrations of air pollutants across years are highly correlated . we fit zero-inflated negative binomial mixed models (zinb) to estimate the associations between long-term exposure to no , pm . , and o and covid- case-fatality rates and mortality rates. the zinb model comprises a negative binomial log-linear count model and a logit model for predicting excess zeros . the former was used to describe the associations between air pollutants and covid- case-fatality rate among counties with at least one reported covid- case. the latter can account for excess zeros in counties that have not observed a covid- death as of july , . we fit single-pollutant, bi-pollutant, and tri-pollutant models, in order to estimate the effects of each pollutant without and with control for co-pollutants. all analyses were conducted at the county level. for the negative binomial count component, results are presented as percent change in case-fatality rate or mortality rate per interquartile range (iqr) increase in each air pollutant concentration. iqrs were calculated based on mean air pollutant levels across all , counties. similar results are presented as odds ratios for the excess zero component. we included a random intercept for each state because observations within the same state tended to be correlated, potentially due to similar covid- responses, quarantine and testing policies, healthcare capacity, sociodemographic, and meteorological conditions. as different testing practices may bias outcome ascertainment, we adjusted for state-level covid- test positive rate (i.e. a high positive rate could imply that the confirmed case numbers were limited by the ability of testing, thus upward-biasing the case-fatality). to model how different counties may be at different time points of j o u r n a l p r e -p r o o f the epidemic curve (i.e., phase-of-epidemic), we adjusted for days both since the first case and since the th case within a county through july . in addition, we adjusted for potential confounders and covariates that may also contribute to heterogeneity in the observed covid- rates and thus may confound associations with long-term air pollution exposure. these include county-level healthcare capacity, population mobility, population density, sociodemographics, socioeconomic status (ses), race and ethnicity, behavior risk factors, and meteorological factors. specifically, healthcare capacity was measured by the number of intensive care unit (icu) beds, hospital beds, and active medical doctors per people . population travel mobility index, based on anonymized location data from smartphones, was used to account for changes in travel distance in reaction to the covid- pandemic . socioeconomic status was measured by social deprivation index , a commonly used measure of area-level ses, composed of income, education, employment, housing, household characteristics, transportation, and demographics. sociodemographic covariates included population density, percentage of elderly (age ≥ ), and percentage of male. race and ethnicity included percentage of black and percentage of hispanic in each county. we also obtained behavioral risk factors including population mean body mass index (bmi) and smoking rate, and meteorological variables including air temperature and relative humidity. additional information about these covariates, including data sources, are given in the technical appendix. to control for potential residual spatial trends and confounding, we included spatial smoothers within the model using natural cubic splines with degrees freedom for both county centroid latitude and longitude. to examine the presence of spatial autocorrelation in the residuals, we calculated moran's i of the standardized residuals of tri-pollutant main models among counties within each state. statistical tests were -sided and statistical significance and confidence intervals were calculated with an alpha of . . all statistical analyses were conducted in r version . . we conducted a series of sets of sensitivity analyses to test the robustness of our results to outliers, confounding adjustment, and epidemic timing (figures and ) . given that new york city has far higher covid- cases and deaths than any other region, we excluded all five counties within new york city in one sensitivity analysis. in another, we restricted the study to the most recent weeks (june to july ), when the case count and death count may be more reliable and accurate compared to earlier periods. we also conducted sensitivity analysis by using air j o u r n a l p r e -p r o o f pollution data averaged between to . to assess the importance of individual confounders or covariates, we fit models by omitting a different set of covariates for each model iteration and compared effect estimates. a total of , us counties were considered in the current analysis, with confirmed cases reported in , ( . %) and deaths in , ( . %). by july , , , , covid- cases and , deaths were reported nationwide ( table ) . among the counties with at least one reported covid- case, the average county-level casefatality rate was . ± . % (mean ± standard deviation), and the average mortality rate was . we observed significant positive associations between no levels and both county-level covid- casefatality rate and mortality rate ( table and figure ), when controlling for covariates. in tri-pollutant models, covid- case-fatality and mortality rates were associated with increases of . % ( % ci . % to . %) and . % ( % ci . % to . %), respectively, per iqr (~ . ppb) increases in no ( table ). these results imply that one iqr reduction in long-term exposure to no level would have avoided , deaths ( % ci: , to , ) among those who tested positive for the virus and . deaths ( % ci: . to . ) per million people in the general population, as of july , . the strength and magnitude of the associations between no and both covid- case-fatality rate and mortality rate persisted across single, bi-, and tri-pollutant models ( figure ). in contrast, pm . was not associated with covid- case-fatality rate ( % ci: - . % to . %) but was marginally associated with higher covid- mortality rate in tri-pollutant models, where one iqr ( . ug/m ) j o u r n a l p r e -p r o o f increase in pm . was associated with . % ( % ci: . % to . %) increase in covid- mortality rate (table ). null associations were found between long-term exposure to o and both covid- case-fatality and mortality rates ( % ci: - . % to . % and - . % to . %, respectively). similar trends persisted across single, bi-, and tripollutant models ( figure ). the moran's i and p-values (appendix table s ) from these models suggested that most spatial correlation in the data has been accounted for. results remained robust and consistent across sets of sensitivity analyses (figures and ). when we restricted the analyses to data reported between june to july , when covid- tests were more readily available, significant associations remained between no and covid- case-fatality and mortality rates, and no consistent associations were found with pm . or o . we also observed similar trends pointing to associations with no when excluding new york city. in addition, we found similar results when omitting the counties ( . %) with missing behavioral risk data. in this nationwide study, we used county-level information on long-term air pollution and corresponding health, behavioral, and demographic data to examine associations between long-term exposures to key ambient air pollutants and covid- death outcomes in both single and multi-pollutant models. we observed significant positive associations between no levels and both county-level covid- case-fatality rate and mortality rate, a marginal association between long-term pm . exposure and covid- mortality rate, and null associations for long-term o exposures in multipollutant models. these results provide additional initial support for the interpretation that long-term exposure to air pollution, especially no -a component of urban air pollution related to traffic -may enhance susceptibility to severe covid- outcomes. these findings may help identify susceptible and high-risk populations, especially those living in areas with historically high no pollution, including the metropolitan areas in new york, new jersey, california, and arizona. given the rapid escalation of covid- spread and associated mortality in the us, swift and coordinated public health actions, including strengthened enforcement on social distancing and expanding healthcare capacity, are needed to protect these and other vulnerable populations. although average no concentrations have decreased gradually over the past decades, it is critical to continue enforcing air pollution regulations to protect public health, given that health effects occur even at very low concentrations . currently, there are few existing studies investigating the link between air pollution and covid- , the majority of which are correlation-only studies without adjustment for confounders. among these sparse studies, our findings are consistent with a recent european study that reported % of the covid- deaths across administrative regions in italy, spain, france and germany, occurred in the five most polluted regions with the highest no levels . another recent paper reported correlations between high levels of air pollution and high death rates seen in northern italy . however, major questions remain concerning the robustness and generalizability of these early findings, due to the lack of control for population mobility, multipollutant exposures, and most importantly, potential residual spatial autocorrelation. the current analysis addresses several of these limitations. we examined two major covid- death outcomes, the county-level case-fatality rate and the mortality rate. the case-fatality rate can indicate biological susceptibility to severe covid- outcomes (i.e. death), while the mortality rate can offer information on the severity of covid- deaths in the general population. our study also included an assessment of three major air pollutants using high spatial resolution maps, uses recent county-level data, considers both single and multipollutant models, and controls for county-level mobility. given that the stage of the covid- epidemic might depend on the size and urbanicity of the county, we included the time of the first and th case for each county in the models as covariates to minimize the possibility that the observed associations are confounded by epidemic timing due to unmeasured location and population-level characteristics. due to the cross-sectional design, we controlled for potential spatial trends by including flexible spatial trends in the main analysis, and evaluated residual autocorrelation using moran's i statistic. our analyses indicated that the presence of spatial confounding was substantial, necessitating the use of spatial smoothing (figures and ) . we performed both stratified analyses and effect modification analyses by adding interaction terms in the model to examine the effects of potential confounders including socioeconomic status. none of these potential modifying effects were significant and were not included in the final analytical modeling approach. finally, we conducted a total of sets of sensitivity analyses and observed robust and consistent results. although social distancing measures around the us have reduced vehicle traffic and urban air pollution in the short-term, it is plausible that long-term exposure to urban air pollutants like no may have sustained direct and indirect effects within the human body, making people more biologically susceptible to severe covid- outcomes. j o u r n a l p r e -p r o o f no can be emitted directly from combustion sources or produced from the titration of no with o . no and nitric oxide (no) have relatively short atmospheric lifetime, thus having larger spatial heterogeneity compared to more regionally distributed pollutants such as pm . and o . as a result, the spatial distribution of no represents the intensity of anthropogenic activity, especially emissions from traffic and power plants. as a reactive free radical, no plays a key role in photochemical reactions that produce other secondary pollutants, including ozone and secondary particulate matter. in our analysis of three major air pollutants, however, no showed strong and independent effects with covid- case-fatality rate and mortality, meaning that the effects of no may not be mediated by pm . and o . even so, we cannot rule out the possibility that no is serving as a proxy for other traffic-related air pollutants, such as soot, trace metals, or ultrafine particles. long-term exposures to no have been associated with acute and chronic respiratory diseases, including increased bronchial hyperresponsiveness, decreased lung function, and increased risk of respiratory infection and mortality - . in addition, as a highly reactive exogeneous oxidant, no can induce inflammation and enhance oxidative stress, generating reactive oxygen and nitrogen species, which may eventually deteriorate the cardiovascular and immune systems , . the impact of long-term exposure to pm . on excess morbidity and mortality has also been well-established [ ] [ ] [ ] . an early unpublished report that explored the impacts of air pollution on mortality found that μg/m pm . was associated with % increase in covid- mortality rates in the usa . the study was conducted in a single pollutant model and did not investigate on covid- case-fatality rates. similarly, we found marginally significant associations between covid- mortality rates and pm . , when controlling for co-pollutants and covariates, although the magnitude and strength of this association observed in the current analysis were weaker, mainly due to our control of the spatial trends, co-pollutants, and residual autocorrelation, which may have confounded the previous study findings. in addition, pm . was not associated with covid- case-fatality rate across all single and multipollutant models, indicating that it may have less impact on biological susceptibility to severe covid- outcomes compared to no . we acknowledge that our study is limited in several key areas. first, the cross-sectional study design reduced our ability to exploit temporal variation and trends in covid- deaths, an important determinant in establishing causal inference. however, an ecological (area-level) analysis may offer valuable information as part of initial public health investigations for hypothesis generation, particularly where individual-level studies may not be possible for some time until fine-scale exposure data become available. towards this end, future time-series j o u r n a l p r e -p r o o f analyses of air pollution and covid- case-fatality rates and corresponding mortality rates will be important. second, there may be complex case ascertainment biases in the county-level covid- data, particularly during the early stages of the outbreak due to lack of reliable testing, which may greatly underestimate the actual covid- case number. while the case data quality gradually improved over the past two months due to enhanced testing capacity, we repeated the analysis using the covid data reported at several time points (by april , by may , by june , and by july ), and the results still hold. third, actual death counts are likely biased, with highly dynamic reported fatality rates, increasing from . % to . %, then decreasing to . % in the past three months - . however, results using data from only the most recent four weeks were largely unchanged, suggesting that differential errors in reporting or testing for covid- may not have exerted much influence on these findings. in this analysis, the air pollution levels were modelled between - , which may introduce bias in the exposure assessment. specifically, given that the average air pollution levels in us have gradually decreased over the years, when using the exposure data between - rather than more recent data, we may have over-estimated the exposure levels, leading to under-estimated health effects. although more recent exposure data were not available, county-specific mean concentrations of air pollutants across years are highly correlated . moreover, we have conducted a sensitivity analysis by using the exposure data between - and the results remained robust and consistent. in addition, although we controlled for many potential confounders such as population density, we cannot rule out the possibility that no might be a proxy of urbanicity. the exclusion of climate meteorological variables and ses -two factors that have received substantial attention regarding the outbreak -did not alter the main results. due to the lack of county-level data, we could not account for the percentage of hospitalized cases or icu use among cases or deaths, the number of available ventilators, and the underlying health conditions of cases likely to increase death risk (e.g., chronic obstructive pulmonary disease). also, as a classic traffic related air pollutant, no can exhibit spatial variation within a county , which may not be captured in our analysis. identification of no pollution hotspots within a county may be warranted. we found statistically significant, positive associations between long-term exposure to no and covid- casefatality rate and mortality rate, independent of pm . as different testing practices may bias outcome ascertainment, we adjusted for state-level covid- test positive rate (i.e. high positive rate might imply that the confirmed case numbers were limited by the ability of testing, and the case-fatality can be biased high). to model how different counties may be at different time points of the epidemic curve (i.e., phase-of-epidemic), we adjusted for days both since the first case and since the th case (i.e., case counts reaching ) within a county through july as a measure of epidemic timing. in addition, we considered potential confounding by county-level healthcare capacity, population travel mobility index, sociodemographic, ses, behavior risk factors, and meteorological factors. because county-specific population densities span orders of magnitude, we adjusted for density using a logarithmic transformation. to control for potential residual spatial trends and confounding, we included spatial smoothers within the model using natural cubic splines with degrees freedom for both county centroid latitude and longitude. we further calculated moran's i of the standardized residuals of tri-pollutant main models for each state, to examine the presence of spatial autocorrelation in the residuals. we also conducted a series of sensitivity analyses to test the robustness of our results to outliers, confounding adjustment, and epidemic timing (figures and ) . given that new york city has far higher covid- cases and deaths than any other regions in the us, which can be a very influential observation, we excluded all five counties within new york city and repeated the analysis. in another set of sensitivity analyses, we restricted the study only to the most recent weeks (june to july ), when the case count and death count may be more reliable and accurate than earlier periods and when covid- tests were more available. we also conducted sensitivity analysis by using air pollution data averaged between to . to assess the impact of potential bias of individual covariates, we fit models by omitting a different set of covariates for each model iteration while comparing effect estimates. statistical tests were -sidedand statistical significance was determined with an alpha of . . all statistical analyses were conducted used r version . . • long-term exposures to urban air pollutants, especially no , may enhance population susceptibility to severe covid- death outcomes. • reduction in urban air pollution exposures would have avoided over , deaths among those who tested positive for the virus as of july , . • public health actions to protect populations from covid- should include considerations for areas with historically high no exposures along with other behavioral and clinical risk factors. the novel human coronavirus disease (covid- ) pandemic has claimed more than , lives worldwide, causing tremendous public health, social, and economic damages. while the risk factors of covid- are still under investigation, environmental factors, such as urban air pollution, may play an important role in increasing population susceptibility to covid- pathogenesis. major ubiquitous ambient air pollutants, including fine particulate matter (pm . ), nitrogen dioxide (no ), and ozone (o ), may have both a direct and indirect systemic impact on the human body by enhancing oxidative stress, inflammation, and respiratory infection risk, eventually leading to respiratory, cardiovascular, and immune system dysfunction and deterioration. although the epidemiologic evidence is limited, a few early crude correlation analyses conducted in china and europe suggest a potential link between air pollution and covid- outcomes. however, questions remain concerning the generalizability and validity of these finding, due to their lack of control for the epidemic timing, population mobility, residual spatial correlation, and potential confounding by co-pollutants. to address these analytical gaps, we conducted a nationwide study in the usa ( , counties) examining associations between multiple key ambient air pollutants, including no , pm . , and o , and covid- case-fatality and mortality rates in both single and multi-pollutant models, with comprehensive covariate adjustment. we hypothesized that residents living in counties with higher long-term ambient air pollution levels may be more susceptible to covid- severe outcomes, thus resulting in higher covid- case-fatality rates and mortality rates. to start this analysis, we obtained the number of daily county-level covid- confirmed cases and deaths that occurred from january , through july , in the contiguous us from three independent databases. the main covid- death outcomes included two measures, the case-fatality rate, which was calculated by dividing the number of deaths over the number of people diagnosed, and the other outcome is the mortality rate, which was calculated as the number of covid- deaths per million population. we include three major criteria pollutants in the analysis, including no , pm . , and o . the high-resolution exposure datasets (daily, km resolution) were generated by our collaborators at harvard using an ensemble-learning method, which integrated three machine learners and a variety of predictor variables. based on these daily predictions from - , we then further calculated the annual mean for no and pm . , and the warm-season mean for o between may to october. case-fatality rate and characteristics of patients dying in relation to covid- in italy the new york times social and environmental risk factors in the emergence of infectious diseases. nature medicine environmental factors on the sars epidemic: air temperature, passage of time and multiplicative effect of hospital infection social, behavioural and environmental factors and their impact on infectious disease outbreaks an imperative need for research on the role of environmental factors in transmission of novel coronavirus (covid- ) ambient particulate air pollution and daily mortality in cities estimates of the global burden of ambient pm . , ozone, and no on asthma incidence and emergency room visits ambient air pollution and emergency department visits for asthma: a multi-city assessment of effect modification by age air pollution and respiratory viral infection. inhalation toxicology effects of nitrogen dioxide on the expression of intercellular adhesion molecule- , neutrophil adhesion, and cytotoxicity: studies in human bronchial epithelial cells use of high-resolution metabolomics for the identification of metabolic signals associated with traffic-related air pollution perturbations of the arginine metabolome following exposures to traffic-related air pollution in a panel of commuters with and without asthma acute pulmonary and inflammatory response in young adults following a scripted car commute air pollution and case fatality of sars in the people's republic of china: an ecologic study association between short-term exposure to air pollution and covid- infection: evidence from china does air pollution influence covid- outbreaks? in: multidisciplinary digital publishing institute health effect institute panel on the health effects of traffic-related air pollution. traffic-related air pollution: a critical review of the literature on emissions, exposure, and health effects. health effects institute the new york times an ensemble-based model of pm . concentration across the contiguous united states with high spatiotemporal resolution assessing no concentration and model uncertainty with high spatiotemporal resolution across the contiguous united states using ensemble model averaging. environmental science & technology area health resources files mobility changes in response to covid- mapping county-level mobility pattern changes in the united states in response to covid- social deprivation index continental-scale water and energy flux analysis and validation for the north american land data assimilation system project phase (nldas- ): . intercomparison and application of model products when adjusted for co-pollutants and confounding factors, per inter-quartile range (iqr) increase in no ( . ppb), covid- case-fatality rate and mortality rate were associated with an increase of . % ( % ci: . % to . %) and . % ( % ci: . % to . %), respectively. in other words, per iqr reduction in long-term exposure to no level ( . ppb) would have avoided , deaths ( % ci: , to , ) among those who tested positive for the virus and . deaths ( % ci: . to . ) per million people in the us general population, as of which largely arises from urban combustion sources such as traffic, may enhance susceptibility to severe covid- death outcomes, independent of long-term pm . and o exposure. public health actions to protect populations from covid- should include considerations for areas with historically high no exposures along with other behavioral and clinical risk factors. continuation and expansion of current efforts to lower traffic emissions and ambient air pollution may be an important component of reducing population-level risk of covid- case-fatality and mortality * descriptive statistics was conducted on , us counties using data reported as of july , **covid- case fatality rate was calculated by the number of deaths divided by the number of cases, reported as of july , key: cord- - qlk y authors: rahmandad, h.; lim, t. y.; sterman, j. title: estimating the global spread of covid- date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: qlk y limited and inconsistent testing and differences in age distribution, health care resources, social distancing, and policies have caused large variations in the extent and dynamics of the covid- pandemic across nations, complicating the estimation of prevalence, the infection fatality rate (ifr), and other factors important to care providers and policymakers. using data for all countries with reliable testing data (spanning . billion people) we develop a dynamic epidemiological model integrating data on cases, deaths, excess mortality and other factors to estimate how asymptomatic transmission, disease acuity, hospitalization, and behavioral and policy responses to risk condition prevalence and ifr across nations and over time. for these nations we estimate ifr averages . % ( . %- . %). cases and deaths through june , are estimated to be . and . times official reports, respectively, at . ( - . ) million and ( - ) thousand. prevalence and ifr vary substantially, e.g., ecuador ( %; . %), chile ( . %; . %), mexico ( . %; . %), iran ( . %; . %), usa ( . %; . %), uk ( . %; . %), iceland ( . %, . %), new zealand ( . %, . %), but all nations remain well below the level needed for herd immunity. by alerting the public earlier and reducing contacts, extensive testing when the pandemic was declared could have averted . ( . - . ) million cases and ( - ) thousand deaths. however, future outcomes are less dependent on testing and more contingent on the willingness of communities and governments to reduce transmission. absent breakthroughs in treatment or vaccination and with mildly improved responses we project ( - ) million cases and . ( . - . ) million deaths in the countries by spring . explanatory mechanisms: a) differences in population density, lifestyle, and interaction patterns create variations in reproduction number. b) risk perception, behavioral change and policy responses alter transmission rates endogenously. c) testing is prioritized based on symptoms and risk factors, so detection rates depend on both testing rates and current prevalence. d) limited hospital capacity is allocated based on symptoms, influencing fatality rates. e) weather may have a role in transmission ( ) while age, socio-economic status, and pre-existing conditions impact severity ( , ) , with the poor and minorities suffering disproportionately ( ) . prior research has addressed different parts of this puzzle, including estimating the infection fatality rate (ifr) in well-controlled settings ( ) or using statistical extrapolation ( ) , assessing the asymptomatic fraction in smaller populations or through random testing ( , ) , and estimating prevalence using random antibody testing in highly affected cities and regions ( ) . yet we lack a global view of the pandemic that is both consistent with these more focused findings and simultaneously explains the large variance in official cases and fatality across different countries. in this paper we build and estimate a multi-country model of the covid- pandemic at global scale. our model captures transmission dynamics for the disease, as well as how, at the country level, transmission rates vary in response to risk perception and weather, testing rates condition infection and death data, and fatality rates depend on demographics and hospitalization. estimating this model using data from every country with more than cases for which testing data is available, we infer some of the key characteristics of covid- pandemic globally and inform how alternative control policies may have played out across the globe. we use a multi-country modified seir model to simultaneously estimate the transmission of covid- in countries. the model tracks community transmission, excluding the global travel network and instead separately estimating the date of introduction of patient zero for each country. within each country, the core of the model tracks the population through susceptible, pre-symptomatic, infected pre-testing, infected post-testing, and recovered states. basic transmission dynamics reflect a classical seir process, with a baseline transmission rate, incubation period, and duration of infection. building on this basic structure the model explicitly represents the dynamics of covid testing, including demand for tests, sensitivity of pcr based testing, and allocation of test capacity between positive and negative cases, as well as the dynamics of hospital system capacity, both with concomitant effects on transmission and mortality. it also endogenously generates population-level behavioral and policy responses due to the perceived risks and government intervention. infected people and those with other risk factors (e.g. hospital workers) or similar symptoms due to other illnesses. we assume, based on prior research ( ) , that infected individuals are potentially tested on average days after the onset of symptoms. on any given day, individuals with more severe symptoms get priority for testing. following ( ) , this prioritization exerts a selection effect that results in different average severity of covid in the tested vs. untested infected populations. we also assume a % false negative rate for pcr-based covid tests ( , ) . a positive test results in reduced contact rates for tested individuals, changing the transmission rates endogenously. thus the model tracks various mechanisms generating the observable measures: a daily reported infection rate that combines the total positive results from each day's tests with daily post-mortem infection confirmations, and a daily reported death rate of confirmed cases. unobserved parameters, such as ifr and asymptomatic fraction, can then be estimated by fitting the model against data for observables. we estimate the effective hospital capacity for each country as a function of total hospital beds available, modified for population density. this modification approximates the effect of geographic heterogeneity in demand for hospital capacity -in larger and less densely populated countries, geographic heterogeneity in the progression of the epidemic means that some areas (e.g. new york city) may be overwhelmed with demand even when other parts of the country have unused hospital capacity. as with testing, hospital capacity is allocated between more severe covid cases (both those tested and those not tested) and demand from non-covid patients. hospitalization can reduce the mortality rate for covid patients, while other determinants of fatality rates are the severity of symptoms and the age distribution of the population ( , ) . each country also exhibits a response to the perceived risk of covid. the response is endogenously driven by a weighted combination of reported and actual hazard of infection. perceived risk drives reduction in contact rate and hence transmission rates through non-pharmaceutical interventions such as social distancing measures. specific government policies are not explicitly represented, but treated as part of this endogenous risk response. different countries could vary in their risk perception, response time, as well as the magnitude of their response based on the perceived risk. overall each country is represented by a system of ordinary differential equations tracking seven population stocks (susceptible, pre-symptomatic infected, infected pre-testing, and four groups of infected post-testing -positively tested or not × hospitalized or not) and a state variable for perceived risk. the model also includes multiple additional state variables for measurement and accounting of e.g. deaths and recoveries. model parameters are specified based on prior literature and formal estimation. main parameters adopted from the literature include incubation period ( days ( , ) ), onset-to-detection delay ( days ( ) ), sensitivity of pcr-based testing ( % ( , ) ), and post-detection illness duration ( days ( ) ). we estimate the remaining parameters using a maximum likelihood approach. using testing rate time series and various country-level data points (e.g. population, hospital capacity, comorbidities, age distribution), the model endogenously simulates confirmed new daily cases and deaths over time and matches them against observed data by maximizing the likelihood of observing those data given the model parameters. we use a negative binomial likelihood function to accommodate excess dispersion in infection and death flows compared to more common gaussian specifications. where data on mean) are . % ( . % for median across countries, med) and . % (med: . %) for cumulative infections and deaths, respectively. r-square values exceed . for % of country-specific cumulative and incidence time series. our projections are also consistent with excess mortality data, where available (see appendix s ). main findings include estimated parameters of covid- epidemics across countries, as well as trajectories of key measures. for estimated parameters we report a) the mean of most likely values across countries (mean); b) the standard deviation of those values (std), which quantifies variability of the underlying concept across countries; and c) the mean of country-level interquartile ranges (miqr), which captures the inherent uncertainty in parameter estimates for each country. the model brings together infection, testing, risk perception, behavioral and policy responses, hospitalization, and fatality using data from across the globe. here we focus on three main results. first, the magnitude of epidemic is widely under-reported with much variation globally. we estimate the asymptomatic fraction to be % (mean; std: . %; miqr: . %). combined with a sensitivity of % ( , ) for pcr tests, the fraction of infections that could potentially be identified without mass testing is limited to %. most countries do not reach this upper bound, however, and testing is the binding constraint. figure -a reports the ratio of estimated to reported infections and deaths, ranging between . and for infections and . to for deaths. in our sample of countries (total population of . billion), we estimate total infections at . ( - . , % credible interval (ci)) million and (ci: - ) thousands by june , . and . times larger than reported numbers respectively. under-counting has been larger earlier in the epidemic. for example, usa faced peak infection rate (of thousands per day) when detection rate was less than % of daily new cases. the most affected countries (based on percent infected) to date include ecuador ( %), peru ( . %), chile ( . %), mexico ( . %), iran ( . %), qatar ( . %), spain ( . %), usa ( . %), uk ( . %), and netherlands ( . %) (see figure -b) . despite the order-of-magnitude under-reporting of cases, however, herd immunity due to infection remains far from reach (figure -b) . the closest a a b . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint country has come to herd immunity is chile, which at its peak infection rate was (ci: days away from infection of % of its total population. second, we quantify both significant heterogeneity, and notable consistency, across countries in terms of basic parameters of the epidemic. the estimated initial reproduction number re ranges between . (indonesia) and . (iran), with the median of . (iceland) (re estimates include significant uncertainty; see figure s for details). even absent endogenous reductions in contact due to realized risk, these initial rates may be higher than longer-term levels for most countries because of early exposures happening in denser social networks. cross-country variations also reflect differences in population density, cultural practices, hygiene, as well as the timing of infection and thus early preparedness. we find support for the impact of weather on reproduction number, with the multiplier (rw) developed by xu and colleagues ( ) explaining transmission rates closely (rw . ). we estimate the global infection fatality rate (ifr) to have been . % (ci: . %- . %), with a wide range (figure -c) between . % (ci: . - . ; qatar) and . % (ci: . - . ; italy). the variations in ifr are primarily due to demographics with elderly having much higher risks ( ) . hospital availability and treatment effectiveness provide a second mechanism affecting fatality rates. we find that hospitalization can bring down risk of death to . % (std: . %; miqr: . %) of baseline. the model explains much variability in ifr with minimum country-level variability in basic fatality parameters. nevertheless, the quality of fit deteriorates in a handful of countries. for example, a ratio of simulated to reported deaths below one in a handful of countries signals that the model expected fewer deaths than observed. notably, we find it hard to reconcile, using only the model's mechanisms, the low fatality rates in qatar, singapore, and thailand relative to infection statistics, and high fatality rates in belgium and france. third, testing regulates transmission dynamics though a few mechanisms. by providing early warning, testing sets in motion the behavioral and policy responses essential to reducing transmission rate and controlling the epidemic. the exponential nature of contagion amplifies small early differences, such that a few days' difference in response time can lead to large differences in peak infection and final epidemic size. behavioral and policy responses to changes in infection risk are adopted rapidly, on average reducing effective contact (and thus transmission) rates in . (std: . ; miqr: . ) days. those responses are relaxed when risks attenuate, though down-regulating risk perception is slower (mean: . ; std: . ; miqr: . days). given limited data on rebounds in infections to date, how quickly perceived risk is downgraded is a major source of uncertainty in projecting the future of the pandemic. we also find that those with a positive test reduce their infectious contacts to a fraction of the original level (mean: . % of original contact rate; std: . %; miqr: . %). these reductions are especially important because asymptomatic individuals are estimated to be less infectious than symptomatic ones (mean: %; std: . %; miqr: . %). finally, by regulating infection rates through the previous two channels, testing also 'flattens the curve', allowing a larger fraction of those in need of medical care to be hospitalized. together, these mechanisms create an early race between testing and the spread of infection ( figure ). when infection is ahead, detection is compromised (moving up into the darker shades in figure) , responses lag further, and exponential infection growth can overwhelm hospital capacity. high early test capacity and its rapid expansion (moving to the right in the figure), brings the epidemic to light, activates policy responses, and allow for control. (panels a and b) shows one alternative testing scenario and counter-factual trajectories of pandemic to date. in this scenario, all countries shift their testing rates from baseline to . % of population per day (a rate currently achieved by multiple countries, e.g. usa, australia, in figure ). the shift happens on march , (the date covid- was officially designated as a pandemic). such enhanced testing would have reduced total cases from . millions to . (ci: . - . ) millions. corresponding reduction in deaths would have been from k to k(ci: k- k). by making additional assumptions on future testing and responses, the model can inform future trajectories. we explore a few projections out to spring that exclude vaccine and treatment availability. figure (panels c and d) shows projections under three scenarios: i) using the current country-specific testing rates and response functions moving forward; ii) if enhanced testing (of . % per day) is adopted on july st p; and iii) if sensitivity of contact rate to perceived risk is set to (approx. th percentile of estimated value across countries), leaving testing at current levels. contrary to the impacts of early differences in testing ( figure -a) , the reductions in future cases from additional testing (ii) are rather modest (from . in i to . billions in ii), because recognition of epidemic is no longer the bottleneck to response. both these scenarios project a very large burden of new cases in the fall , with hundreds of millions of cases concentrated in a few countries estimated a b c d . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint to have insufficient responses given perceived risks (primarily india, but also bangladesh, pakistan, and usa). in contrast, changes in response policies would make a major difference. scenario iii brings down future cases sharply, to as low as (ci: - ) millions (cumulatively) by the end of winter. across scenarios, we find that the infection rate in each country usually peaks and then stabilizes at a lower and slowly declining linear rate, in some cases after damped oscillations (i.e. second waves). these (approximately) steady-state infection rates are at levels that motivate just enough policy and behavioral response to bring effective reproduction number re to . faster rates lead to exponential growth, raise alarms and bring down contacts; slower ones lead to relaxation of policies bringing the reproduction number back up to . those post-peak infection rates vary widely across countries and depend on risk perception parameters, time constants, and contact sensitivity to risk, as well as weather and susceptible population size. in this scenario we shift both testing and contact sensitivity to perceived risks to arguably more realistic values between current ones and those in scenarios ii and iii in figure -c. specifically, on july st we shift test rates to a value % between the current rates and . % per day (which increases testing in most countries and reduces it in a few). similarly, sensitivity of contacts to perceived risk is shifted to % of the way between estimated country-level values and a high value of . resulting infection and death rates at the end of this period reflect the post-peak burden of the disease discussed above and are estimated at . % (ci: . - . ) and . e- % (ci: . e . appendix s provides projections for all countries. note that projections are highly sensitive to assumed testing, behavioral, and policy responses in the scenario. as such they should be interpreted as indicators of potential risk and not precise predictions of future cases; more rigorous testing and reductions in contacts in response to risk perception will significantly reduce future cases while laxer response and normalization of risks can lead to overwhelming breakouts. to enable empirical estimation and considering limits to data availability at a global scale, the model includes important simplifications and uncertainties that should temper the interpretation of the results. first, by analyzing an aggregate, country-level model, we abstract away much heterogeneity, from social networks to super-spreaders and local events. moreover, we offer no explanation for the underlying heterogeneity in reproduction numbers across countries. second, lacking hospitalization data across the world, the model's hospital sector includes additional uncertainty. similarly, our estimated behavioral and policy response functions do not tease apart the impact of various determinants such as national and local policies, business and event closures, use of personal protective equipment, reductions in physical interactions, and a host of other contributors. thus, results are not informative about the effectiveness of specific policies, and extrapolation of response function in future scenarios includes unknown uncertainties. for example, if normalization of risk reduced response magnitude in the second wave, our projections would miss that and prove optimistic. finally, absent explicit travel network our results would under-estimate the risk of the reintroduction of the disease in locations that have contained the epidemic. this paper provides a systemic view of the covid- pandemic globally. by incorporating testing capacity and prioritization, hospitalization, and risk perception and responses into an epidemiological model, we are able to closely match widely varying country-specific trajectories of the epidemic. our model explains the observed heterogeneities primarily through three pathways. first, estimates point to much variance in initial reproduction numbers across countries. this heterogeneity is not surprising given that reproduction number is very much a function of human behaviors and interaction is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . environments. nevertheless, our study was not designed to tease out the sources of that heterogeneity, an important task that requires other types of data and analysis. second, the course of the epidemic is also significantly impacted by risk perception and behavioral and policy responses that vary notably across different countries. finally, we show that differences in testing rates play an important role in shaping those trajectories. despite those variations, we also find much that is consistent across the globe: a) we estimate that just over half of the infections are asymptomatic, consistent with detailed estimates from smaller samples ( , , ) . b) we estimate that asymptomatic individuals are about a third as infective as symptomatic patients. c) in our model, hospitalization brings down fatality substantially, highlighting the crucial importance of keeping cases below hospital capacity. d) we find an average global infection fatality rate close to . %. this is consistent with growing evidence on ifr ( , ) . our estimates for ifr change predictably with age, and require few other predictors and no country-specific factors to stay consistent with the data. e) an order of magnitude under-reporting of cases is the norm across most countries, with a few percent of population already infected across many nations; nevertheless, herd immunity remains distant. f) finally, absent notable improvements in country level responses or breakthroughs in vaccination or treatment, the outlook for the epidemic remains grim, with most nations settling into a steady state of cases and deaths that, while below their peaks, are troublingly large. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . the model simulates the evolution of covid- epidemic, risk perception and response, testing, hospitalization, and fatality at the level of a country. here we explain key equations and structures in each sector, followed by complete listing of model equations and parameters in s . the model is a derivative of the well-known seir (susceptible, exposed, infectious, recovered) framework for simulating infection dynamics. figure s provides an overview of key population groups and the population movements among them . . we assume demand for testing and hospitalization are driven by symptoms, so all asymptomatic patients will be in the latter category. in the equations below we use short-hands to simplify mathematical notations. the full model documentation uses full variable names. table s provides the mapping between the short-hands and the full names, as well as the sources and equations for those variables and parameters discussed below. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint from these infectious categories, resolution flows (r…) take individuals to either recovered (r…) or dead (d…) states, with corresponding subscripts u, c, ch, and uh for stocks and uu, uhch etc. for flows. given the differences in severity and potential survival extension due to hospitalization, we distinguish between resolution delay for those in hospital (hospitalized resolution time; τh) and those not hospitalized (post-detection phase resolution time; τr). we use first order exponential delays for all lags, though sensitivity analyses showed very little impact of using higher order delays. the infection rate (rsp) controls the flow from s to p and depends on infectious contacts (ci), fraction of total population (n) that is susceptible, and weather effect on transmission (w). the latter is a function of rw, the country-level projections for impact of weather on covid- transmission risk year-round developed by xu and colleagues ( ) and a parameter, sensitivity to weather (sw), to be estimated: infectious contacts depend on the reference force of infection (β), various infectious sub-populations (and their relative transmission rates; ma for asymptomatic and mt for confirmed), and contacts relative to normal (fc), which captures behavioral and policy responses as a fractional multiplier to baseline infectious contacts: in this equation we separate various stocks (of i and p) into asymptomatic (a superscript) and symptomatic (s superscript). that distinction is treated analytically using a zero-inflated poisson distribution that is discussed in the next section. in light of evidence on the short serial interval for covid- , likely below the incubation period ( , ), we do not distinguish the infectivity of pre-symptomatic individuals from those post onset. contagion dynamics start from patient zero arrival time, t , another estimated parameter. the key mechanisms regulating the population flows among these stocks are discussed below, and a schematic of important relationships is provided in figure s . five parameters are estimated in the equations discussed above. one of them (sw) is global (i.e. assumed identical across countries; see the estimation section below for details on the distinction between global and country-specific parameters) and the remaining four are country-specific: β, mt, ma, and t . . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . covid- infection varies in acuity, from asymptomatic to life-threatening. acuity of disease affects notonly baseline fatality risk, but also testing and hospitalization decisions which impact official records of infection and fatality rates. since movement between population groups via testing or hospitalization is itself a function of acuity, to allow for consistent inference of mean acuity across different population groups, we use an analytical framework to track acuity levels. this framework, which we adapted from prior research ( ) , obviates the need to disaggregate the population by different acuity levels (which would prohibitively raise the computational costs for estimation). specifically, we represent acuity using a zero-inflated poisson distribution. this distribution combines two subpopulations -one with poisson-distributed acuity levels with mean covid acuity (αc), and another additional asymptomatic fraction with zero acuity, which is the zero-inflated component. the sum of those with zero acuity from the poisson part of the population and the second group is the total asymptomatic fraction (a). we assume this asymptomatic group is not given priority in testing or hospitalization, and is not at risk of death. thus they will always follow the → → → → pathway. the pathways for the remaining population depend on acuity and its impacts on testing, hospitalization, and death. note that the concept of acuity defined here only needs to have a monotonic relationship with tangible symptoms and risk factors and it does not have a one-to-one relationship with any real world measure of acuity, and as such is better seen as a mathematical construct that informs modeling rather than a real-world variable with clinical definition. from this framework two parameters, a and αc, are estimated as country specific parameters with limited variability across countries. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint the testing sector reads the active test rate (tt) for each country as exogenous input data (see appendix s for pre-processing details for this data). a fraction of this total test rate, typically small, is allocated to postmortem testing of covid- victims who have not been previously confirmed (post mortem tests total, tpm). specifically, of the deaths of unconfirmed infectious individuals (whether hospitalized or not), a certain fraction of fatalities screened post mortem (npm) will be identified true post-mortem tests. we anchor the npm to fraction covid death in hospitals previously tested (ndch). the rationale for this anchoring is that on the margin if there are many unidentified covid patients in hospitals, the chances are that the system lacks enough testing capacity and thus post-mortem testing should also be less thorough: we experimented other functional forms with a free parameter connecting the two constructs, but following our conservative estimation principle decided against including that free parameter in the final model. we feared that absent clear observables to identify this additional parameter (e.g. on country-specific policies regulating post-mortem testing) the degree of freedom would improve the fit but potentially for the wrong reason. the where the multiplier recent infections to test (mit), captures the sensitivity of negative test demand to recent infection reports. to allocate the available tests (tnet) between these two sources of demand, we use an analytical logic that allocates testing based on acuity of symptoms. the basic idea is that through self selection and screening by testing centers, people who have more symptoms or other signals that correlate with covid infection (e.g. high exposure risk) are more likely to be tested. we assume each unit of acuity increases the likelihood that an individual gets tested, based on a variable prob missing symptom, pms. this variable represents the probability that each acuity unit fails to convince the testing decision process to test a given individual, i.e. how selectively and sparingly tests are conducted. specifically, in this model an individual with k acuity units is tested with probability: we assume the negative test demand is coming from a population with a poisson-distributed, unit average acuity level (αn= ) for symptoms of non-covid influenza-like illnesses. the test demand from covid . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint patients also comes from a poisson distribution of acuity, but with mean αc. with the poisson distribution and given a level of α and pms, one can calculate the fraction of each demand source that would be tested: we therefore need to find the pms that allows test supply to match demand that is satisfied, specifically, by solving the following equation for pms*: having solved for p*ms (numerically), we analytically calculate the average acuity level for those positively tested (αcp: average acuity of positively tested ) and those either not tested or having received a false negative result (αcn). specifically, if test sensitivity was %, the average acuity for those not tested would be: the acuity level for those tested could then be found based on the conservation of total acuity across those positively tested and those not. starting with this basic specification we further account for the sensitivity of covid test (st) to calculate the values of αcp and αcn. we parametrize sensitivity at %, which is the estimated sensitivity for the pcr-based tests used as the primary diagnosis method of current infections of covid- ( , ) . overall, the testing rates that are determined by solving for * , combined with sensitivity of tests, inform the fraction of covid positive individuals transitioning from pre-detection (ip) to confirmed vs. unconfirmed states (ic or ich vs. iu or iuh), while the calculated α values inform the likelihood of hospitalization and fatality rates, as discussed next. the testing sector includes the following two country level parameters that are estimated: nst, mit. the hospitalization sector of the model starts with each country's nominal hospital capacity (hn) in total hospital beds. in practice, geographic variation in hospital density and demand creates imperfect matching of available beds with cases of covid- at any point in time, e.g. because some potential capacity is physically distant from current covid hotspots. this imperfect matching means some of the nominal hospital capacity is effectively unavailable at any time, especially in larger, less densely populated countries. we therefore calculate effective hospital capacity (he) by considering geographic density of hospital beds (bed per square kilometer; dh): where the * represents a large reference hospital density of . beds per km (which is the value of for south korea). the parameter sdh (impact of population density on hospital availability) is estimated. effective capacity is allocated between potential hospital demand (hcd) from covid- cases and the regular demand for hospital beds from all other conditions (which we assume equals pre-pandemic effective hospital capacity). we assume that covid- patients will have higher priority for hospitalization compared to regular demand. specifically, we assume that fraction of regular demand allocated (mhr) would be the . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint square of that for covid demand (mhc), = , and solve the resulting hospital capacity allocation problem analytically: we determine the covid demand for hospitalization based on a screening process similar to that for testing. two types of covid patients may seek hospitalization: those with confirmed test results and those without. the former are more likely to seek hospital treatment. we first calculate a parameter analogous to pms in the testing sector that informs the demand from confirmed covid patients for hospitalization. this parameter, the pmas confirmed for hospital demand (pmhc) is determined based on acuity level of confirmed (αct) and reference covid hospitalization fraction confirmed (rh), an estimated parameter capturing the overall need for hospitalization among covid patients: for unconfirmed covid patients we scale the analogue of this parameter (pmhu) based on how much priority non-covid patients generally receive: this formulation ensures that: ) confirmed covid patients are more likely to be hospitalized, but also that ) if there is ample hospital capacity (mhr~ ), then confirmed and unconfirmed covid patients will receive similar priority for the same level of acuity. in short, the pm. values determine hospital demand by confirmed and unconfirmed covid patients, which add up to hcd. the latter determines the fraction of hospital demand that is met. analogous to the testing sector, this fraction along with demand determines the flow of individuals from the pre-detection (ip) state to hospitalized vs. non-hospitalized states (ich or iuh vs. ic or iu). matching demand to allocated capacity also allows us to calculate the realized probability of missing acuity signal at hospitals (p*m) for confirmed and unconfirmed patients. as in the testing sector, those probabilities let us approximate for the expected acuity levels for covid patients in and out of hospital, as well as tested vs. not-tested, i.e. αct, αch, αu, and αuh. these average acuity levels in turn inform fatality rates for each group. the hospital sector includes two country level estimated parameter with limited variation across countries: sdh and rh. for patients in each of the u, c, ch, and uh groups we specify the infection fatality rate (f), as: the parameter base fatality rate for unit acuity (fb) sets the baseline for fatality rate. sensitivity of fatality rate to acuity (sf) determines how fatality changes with estimated acuity levels; more severe cases are expected to have higher fatality rates. hospitalization reduces fatality rates, expressed as the relative impact of treatment on fatality rate (shf). the function incorporates the impact of age distribution on fatality rates. for age effect, we calculate a risk factor for each country based on its age distribution and the relative fatality risks for covid patients in different ages documented in prior work ( ) . we normalize this factor . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint against its value for china where the original study was conducted. given the well-established impact of age on fatality, this factor is directly multiplied into the infection fatality equations. overall, the fatality sector includes three parameters that are estimated at the country level, with limited variance across countries, those are: , , and . note on comorbidities and fatality: we also explored including three comorbidities but found the estimates unreliable and therefore they are not included in the main specification of the model. those comorbidities include obesity, chronic disease, and liver disease. the effects we explored for each were: (.) = (.) (.) , where we used the following country-level indicators from the world health organization ( ), normalized by the average across all countries (d(.)): for obesity: prevalence of obesity among adults, bmi ≥ (age-standardized estimate) (%) for chronic health issues: probability (%) of dying between age and exact age from any of cardiovascular disease, cancer, diabetes, or chronic respiratory disease for liver disease: liver cirrhosis, age-standardized death rates ( +), per , population in equation we noted that contacts relative to normal (fc) regulates infection rates. this factor ranges between a minimum (min contact fraction; cmin) and as a function of the relative utility from normal activities (un) compared to utility from limited activities (ul) in light of additional risks associated with normal activity patterns: the utilities from normal and limited activities are specified as . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint overall, the risk perception and response sector includes the following five country-specific parameters that are estimated: cmin, τru, τrd, λ, and wr. table s summarizes the main equations discussed in appendix s , providing the mapping between full variable names and the short forms. it also includes all estimated model parameters, as well as those specified based on prior research. table s -mapping between full variable names and their short form for the subset of variables and parameters discussed in s . also included are equations explained above and sources for other variables. is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint the model we estimate is nonlinear and complex, and any estimation framework is unlikely to have clean analytical solutions or provable bounds on errors and biases. therefore, in designing our estimation procedure, we set out to be conservative. specifically: we use a likelihood function that accommodates overdispersion and autocorrelation (negative binomial); we utilize a hierarchical bayesian framework to couple parameter estimates across different countries which reduces the risk of over-fitting the data; and we use the conceptual definitions of parameters and their expected similarity across countries to inform the magnitude of that coupling across countries. compared to more common choices in similar estimation settings, these choices tend to widen the credible regions for our estimates and reduce the quality of the fit between model and data. in return, we think the results may be more reliable for projection, more informative about the underlying processes, and better reflective of uncertainties in such complex estimation settings. the model is a deterministic system of ordinary differential equations with a set of known and unknown parameters. the known parameters are those specified based on the existing literature and do not play an active role in estimation. the unknown parameters can be categorized into those that vary across different countries and those that are the same across all countries (i.e. general parameters). the estimation method is designed to identify both the most likely value and the credible regions for the unknown parameters, given the data on reported cases and deaths (and for a subset of countries, the excess deaths). this is done through a combination of estimating the most likely parameter values in a likelihood based framework, and using markov chain monte carlo simulations to quantify the uncertainties in parameters and projections. we first introduce the different components of the likelihood function we use: the fit to time series data, the random effects component coupling country-level parameters, and the penalty for excess mortality. then we explain the implementation details. define model calculations for expected reported cases and deaths for country i as μij(t) (with index j specifying cases and deaths) and the observed data for those variables as yij(t); the country-level vector of unknown parameters as and the general unknown parameters as ϕ. note that vector includes several parameters, each specifying an unknown model parameter, such as impact of treatment on fatality, or total asymptomatic fraction, for country i. the model can be summarized as a function f that produces predictions for expected cases and deaths for each country given the general and country-specific parameters: we use a negative binomial distribution to specify the likelihood of observing the y values given θ and ϕ. specifically, the logarithm of likelihood for observing the data series y given model predictions μ(θ ,ϕ) is: where (dropping time index for clarity): . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . summing the lt function over time provides the full (log) likelihood for the observed data given a parameterization of the model. the negative binomial likelihood function includes two parameters, μ and ε which determine the mean and the scaling/shape of the observed outcomes. the second parameter, ε, provides the flexibility needed fit outcomes with fat tails and auto-correlation. this parameter could itself be subject to search in the optimization process. specifically, we assume that: thus we create a (set of) country specific parameter(s) ( ) and two general parameters ( ) which should be estimated along with the conceptual model parameters. the country level scale ( ) implicitly assesses the reliability and inherent variability in country level reports, and the general ones inform the variability in case data vs. deaths. we augment the vectors ϕ and θ to include these scaling parameters as well. up to this point we have not included any relationship among country specific parameters, . this independence assumption would allow parameters representing the same underlying concept to vary widely across different countries. such treatment, by providing more flexibility, enhances the model's fit to historical data. however, it ignores the conceptual link that exists for a given parameter across countries, potentially allowing the model to fit the data for the wrong reasons (i.e. using parameter values that do not correspond to meaningful real world concepts). the result would likely be less reliable and also not robust for future projections. we therefore define a hierarchical bayesian framework to account for the potential dependencies among model parameters. specifically, we assume the same conceptual parameters (e.g. impact of treatment on fatality), across different countries, are coming from an underlying normal distribution with an unknown mean (to be estimated) and a pre-specified standard deviation. this assumption is similar to the use of "random effect" models common in regression frameworks, though we deviate from canonical random effect models by pre-specifying the standard deviation. in fact it is possible to estimate the standard deviation across countries as well (and to obtain better fits to data), but adding those degrees of freedom ignores qualitatively relevant insights about the level of coupling across different countries for each parameter, and thus results may fit the data better but for the wrong reasons. for example, some parameters, such as patient zero arrival time, could be very different across countries, whereas parameters reflecting innate properties of the sars-cov- virus itself (e.g. total asymptomatic fraction (a)) or those determining fatality (e.g. base fatality rate for unit acuity (fb)) should be very similar across different countries. allowing the model to determine the variance for the latter will lead to better fits: the model can find baseline fatality rates that easily match fatality variations across countries, and would expand the corresponding variance parameter accordingly. however, as a result the estimation algorithm will have too easy a job: it will not require a precise balancing between hospitalization, impact of acuity on fatality, and post-mortem testing decisions to fit fatality data. thus, the estimates may well be less informative, or further from true underlying processes and the general characteristics of the disease which we care about. the implementation of this random effect introduces another element to the overall likelihood function: here θik represents the k th parameter for country i, and ̅ is the (estimated) average across countries for the k th parameter. σk is the pre-specified allowable variability for the k th parameter across different countries. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint specifying these standard deviations adds a subjective element to the estimation process. however, we note that subjective elements are ultimately indispensable in any modeling activity: from specifying the model boundary to the level of aggregation, use of various functional forms, and choice of likelihood functions, these choices are built on subjective assessments that experts bring to a modeling project. absent our conceptually informed variability factors, we would need to make the assumption that country-level parameters are independent, or that our complex estimation process would correctly identify the true dependencies among those parameters. we think both those alternatives are inferior in the chosen method. so here we focus on transparently documenting and explaining those assumptions. table s summarizes the estimated model parameters, their estimated values (mean across countries and mean of inter-quartile range) and the assumed variability factor (σk) for each. sw sensitivity to weather . (global parameter so the other metrics do not apply) *given the wide range and potential long tail for these parameters the log transformation is used in specifying the dispersion penalty (equation ) and variability factors are reported as σ , where σ is used in equation . ** these parameters are expected to be less variable across countries and thus are assigned small variability allowances compared to their mean. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint finally, we include a likelihood-based penalty term to allow model predictions be informed by excess mortality data collected by various news agencies and researchers for a subset of countries in our sample. these data provide snapshots of excess mortality (compared to a historical baseline) for a window of time in each country. subtracting from total excess mortality the covid- deaths officially recorded in that window offers a data point for excess mortality not accounted for in official data (ei). we can calculate in the model the counter-part for this construct: the simulated mortality that is not included in the simulated reported covid- deaths ( ̅ ). there is uncertainty in these excess mortality data: the historical baselines used by various sources do not adjust for demographic change, excess mortality may be due to factors other than covid- , and some of it may be due to changes in healthcare availability and utilization motivated by covid- but not directly attributable to the disease (for example when surgeries are delayed, hospitalization is avoided, or heart conditions are ignored). excess mortality may also be reduced due to reduced traffic accidents (in light of physical distancing policies) and pollution related deaths. given these uncertainties, we use the following penalty function to keep the simulated unaccounted excess mortality close to data: this penalty could be seen as a likelihood coming from the probability distribution ( ) = should be attributed to covid- deaths, but that there is significant uncertainty around this, so some % variation across this figure is quite plausible ( %- % of data). however, numbers outside of this range start to impose increasingly large penalties, so that very large deviation becomes unlikely. combining these three components, we obtain the full likelihood function used in the analysis: for each country we include the lt component from the first day they have reached . % of their cumulative cases to-date, or a minimum of cumulative cases. this excludes very early rates that are both unreliable and which, given very small estimated model predictions for infection, could lead to unreasonably large likelihood contributions. the model includes a large number of parameters to be estimated: a general parameter for the impact of weather, general parameters for , and parameters for each country that are coupled together based on the random effects framework described above. out of those parameter is for and the rest are informing various features of disease transmission, testing, hospitalization, and risk perception and response. with a sample of countries, this would lead to about parameters to be estimated. a direct optimization approach to this problem suffers from potential risk of getting stuck in local optima, and direct use of mcmc methods to find the promising region of parameter space suffers from the curse of dimensionality. we therefore designed the following -step procedure to find more reliable solutions to both problems. ) we estimate the model with the full parameter vector for a smaller number of countries with larger outbreaks ( - countries). we use the powell direction search method implemented in vensim™ simulation software for this step. the method is a local search approach though it has features that allows it to escape local optima in some cases. we restart the optimization from various random points in the feasible parameter space and track the convergence of those restarts to unique local peaks. we stop this process when we are repeatedly landing on the same local peaks in the parameter . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint space. this procedure showed that local peaks do exist, but they are not many; for example within restarts we may find - distinct peaks. this provides a coherent set of starting points for ϕ and ̅ for next steps. ) we go through iterations of the following two steps: a) conduct country-specific optimizations with restarts to find the vector of θi given the ϕ and ̅ from first optimization or from the step b. b) conduct a global optimization, including all countries but fixing θi and optimizing on ϕ (and ̅ ; though that is simply the mean across country level parameters from previous round). we stop when iterations offer little improvement from one round to the next (less than . % improvement in loglikelihood). ) we conduct a full optimization allowing all parameters (θi, ϕ and ̅ ) to change, starting from the point found in the last iteration of step . this step finds the exact peak on the likelihood landscape which is the best-fitting parameter set for the model. ) for the mcmc, theoretically one should conduct the sampling from all model parameters in the full model. however, our experiments showed that the large dimensionality of the parameter space requires an infeasible number of samples to achieve adequate mixing and ensure reliable credible regions for parameters and projections. to overcome this challenge we note that the parameters of different countries are connected to each other only through ϕ and ̅ , and these general parameters are rather insensitive to dynamics in each country. the insensitivity is due to the fact that a single country only contributes about % to the general parameters' values, and within a typical mcmc the country-level parameters often can't change more than % before the resulting samples become highly unlikely. therefore, one can conduct an approximate country-level mcmc by fixing the general parameters at those from step , and only sampling from the θi for each country. the mcmc algorithm used is one designed for exploring high dimensional parameter spaces using differential evolution and self-adaptive randomized subspace sampling ( ) . using this method we obtain good mixing and stable outcomes (robin-brooks-gelman psfr convergence statistic remaining under . ) after about , samples (the burn-in period). we continue the mcmc for each country for million samples and then randomly take a subsample of those points after the burn-in period for the next step. ) the resulting subsamples for different countries from step are assembled together to create a final sample of parameters for the full model to conduct projections and sensitivity analysis at the global scale. uncertainties in the handful of global parameters is not identified in this procedure, but can be quantified by assessing the sensitivity of the global likelihood surface to changes in those parameters. the process above is automated using a python script that controls the simulation software (vensim). we conduct the analysis using a parallel computing feature of vensim on a windows server with cores. after compiling the simulation model into c++ code (which speeds up calculations significantly), and using a simulation time step of . days, it takes about hours to complete the estimation for countries. full analysis code is available online at https://github.com/tseyanglim/covidglobal. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint s -data pre-processing getting contemporaneous, comprehensive, national-level data on covid- is a challenge. the most widely-cited data aggregators, such as the johns hopkins center for systems science and engineering's covid- database ( ) , ourworldindata portal ( ), and the us-focused covid tracking project ( ), get their data from the same few official sources, such as the us centers for disease control and prevention (cdc), the european cdc (ecdc), and the world health organization (who). these official agencies in turn get their data from national and subnational public health authorities, which ultimately rely on reports from hospitals, clinics, and private and public health labs. as a result, idiosyncrasies in the ground-level data collection processes permeate virtually all sources of aggregate data. most notably, data collection involves time lags, which can differ from source to source. daily death counts could reflect the date of actual death or the date a death is registered or reported; different uk government sources, for instance, use each of these metrics. daily infection or case counts could include the total new cases reported on a given date, or the total cases confirmed from that date; the latter would result in some 'backfill' whereby case counts for previous days can continue to increase for some time as delayed confirmations come in. daily counts of tests conducted could report samples collected, samples processed, results reported, or a mix of these; the us cdc, for instance, reports a mix of testing by date of sample collection and date of sample delivery to the cdc. aside from differences in unit of measure (people vs. tests vs. samples), there may be different time lags involved as well. in addition to these idiosyncrasies, testing data in particular is also patchy for many countries, even as testing has become more widespread. the who does not report country-by-country testing, nor does the jhu covid map outside the us. furthermore, there are sometimes irregular delays in the reporting of test results, which can create occasional unexpected spikes in reported numbers of tests, infections, or both. depending on the specifics of how daily infection and test counts are reported, there can in some cases be a disjunction between the two. because confirmed case counts largely depend on positive test results, test and infection counts should be correlated -ceteris paribus, a day with a lot of samples collected for testing should see more confirmed cases attributed to it, while a day with no sample collection should see no cases. but since cases may not be reported by the date of the test, and tests may not be reported by the date of sample collection, officially reported numbers can get out of sync in either direction. this problem is most salient when there are clear weekly cycles in daily rates. in most of the world, particularly western countries, daily test rates are far lower on weekends than during the week. as a result, infection numbers show a clear weekly cyclical component as well. but the weekly cycles in testing and infection numbers for a given country do not always line up. our model explicitly accounts for the effect of testing on reported infections, but we do not explicitly model the country-level idiosyncrasies of reporting and how they vary between test data and infections. instead we account for any such lags in pre-processing of the data to align testing and case data. the weekly cycle occurs in many countries' death rate data as well, where it presents a different problem. a weekly cycle in testing is a behaviourally realistic part of the data-generation process, as many labs, clinics, or other testing sites for instance may be closed on weekends. as testing provides the window on the state of confirmed infections, a comparable cycle in confirmed cases is to be expected as well. by linking case confirmations to testing, our model explicitly accounts for this limited visibility on the true state of the epidemic. however, a weekly cycle in death rates almost certainly reflects different limitations of the data- https://blog.ons.gov.uk/ / / /counting-deaths-involving-the-coronavirus-covid- / https://www.cdc.gov/coronavirus/ -ncov/cases-updates/previous-testing-in-us.html see e.g. https://www.wcvb.com/article/massachusetts-coronavirus-reporting-delay-due-to-quest-lab-itglitch/ # . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint generation process, typically to do with hospital staffing, which we do not explicitly model. as such we need to address any weekly cycle in death rates through data pre-processing as well. to deal with these challenges, we developed a multi-step algorithm to pre-process our data before feeding it into the model for calibration. the algorithm is described below. it was implemented in python, largely using the pandas and numpy packages, and the code is available in full at: https://github.com/tseyanglim/covidglobal. the algorithm proceeds country-by-country, following these steps on each country. ) examine daily cumulative test data; if data are insufficient ( or fewer data points), drop country from the dataset. ) interpolate any missing daily cumulative test data points using a piecewise cubic hermite interpolating polynomial (pchip) spline. if the first reported infection is before the first reported cumulative test, also extrapolate cumulative tests back to the date of first reported infection. a. extrapolation to the date of first reported infection is necessary since both in the model and, to a large extent, in reality, reported infections require testing for confirmation. b. pchip spline interpolation yields a continuous monotonic function with a continuous first derivative, thus avoiding generating any anomalous rapid change in daily test rate. c. we used the implementation of pchip interpolation from the widely used scipy package for python. ) calculate daily test rate as daily cumulative tests less the preceding day's cumulative test total: ) examine the original daily cumulative test data to estimate how much of the calculated daily test rate is based on interpolated vs. original data. a. daily test rates calculated based on mostly original data should be expected to include any weekly cycles or occasional irregularities that would also be reflected in daily infection counts. conversely, daily test rates calculated from cumulative test counts that are largely interpolated would not be expected to fully reproduce any such cycles or irregularities, since the interpolation produces a relatively smooth function. b. as a rule of thumb, we examine the cumulative test data for the second half of the time from the first test to the latest test. if fewer than half the days in that window have original cumulative test data, we consider the test data to be 'sparse', requiring further processing. it may be argued that there are weekly cycles in large-scale human behaviour that may drive some true weekly cyclicality in the true rates of infection and death, and as such it may be wrong to consider such cycles to be artefacts of the datageneration process. however, we find this unlikely for a few reasons. first, weekly cycles in human interactions, largely driven by the work and school week and weekend, will have been significantly attenuated by widespread adoption of social distancing measures around the world. second and more importantly, variation in incubation period and time before development of symptoms means that any true cyclicality in the timing of initial infection will be further attenuated in the timing of symptom development. by the same logic, wide variability in the delay from symptom development to death means there should be minimal cyclicality, if any, in the timing of deaths, meaning any such cycles visible in the data are due to measurement and reporting lags. https://docs.scipy.org/doc/scipy/reference/generated/scipy.interpolate.pchipinterpolator.html . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint ) if the test data are not sparse, account for any potential lag or other reporting delay differences between daily test rate and daily infection rate using a time-shift algorithm to estimate any such lags or delays from the data and shift the test rate time series accordingly. the time-shift algorithm ensures that any weekly cycles present in the daily infection rate data are reflected in the daily test rate data and aligned as best as possible on date, thereby accounting for the fact that model-generated reported infections depends on testing but with no time lag between test and result. a. first, identify the weekly component of the time series of daily infection rate and daily test rate using a seasonal-trend decomposition based on loess (stl) procedure. i. stl deconstructs time series data into several components, including a trend and a seasonal component over a specified period (weekly, in this case) as well as a residual. stl is an additive decomposition, and has the advantage of allowing the seasonal component to change over time (rather than being a fixed pattern repeated exactly across the whole time series). ii. we used the stl implementation from the statsmodels package for python. b. shift the time series over a one-week range (from - to + days of lag between test and infection reporting), calculating the cross-correlation between the weekly seasonal component of the daily infection rate data and the daily test rate data for each time shift. c. identify the time shift within this range that maximizes the cross-correlation between the infection rate and test rate data, and shift the test rate data accordingly. ) if the test data are sparse, the spline interpolation will generally cut out some of any weekly cyclicality that may be present. visual inspection of daily test rates for countries with sparse test data also shows large, irregular spikes in reported tests are not uncommon, without necessarily having concomitant irregular spikes in reported daily infection rates. as such, rather than attempting to eliminate differences in reporting lags through the time-shift algorithm described above, we instead apply a data-smoothing algorithm to both daily test rate and daily infection rate, in order to reduce any cyclicality and irregular spikes. this smoothing allows the calibration of the main model to focus on matching the underlying trends in the data. in all cases, whether daily cumulative test data are sparse or not and whether infection and test rate data are smoothed or not, since weekly cycles in death data are reflective of reporting lags not captured in the model, daily death rate data is smoothed using the same algorithm. ) the smoothing algorithm used is designed first to conserve the total number of reported cases (tests, infections, or deaths), and second to preserve some degree of variation in the time series, as some noise may be informative and retaining some is important to the calibration of the model. a. starting from when the time series of daily rate (test or infection) exceeds a specified minimum value ( /day), calculate the rolling mean of the daily rate, using a centred moving window of days. b. calculate the residual between each day's data point and the rolling mean for that day, and divide by the square root of the rolling mean, to get an adjusted deviation value: i. dividing by the square root of the rolling mean reflects a heuristic assumption that each daily rate (of infections, deaths, or tests) behaves as a poisson process (stdev of pois() =  . ). is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint ii. the functional result of this adjustment is that both absolute and relative magnitudes of deviations from the rolling mean are given some weight -large relative deviations when absolute values are small (and data are noisier) are not ignored, but neither do they outweigh larger absolute (but smaller relative) deviations that occur when the mean is large, which is important since most of the time series data are growing significantly over the time horizon of the model. c. calculate thresholds for identifying dips and peaks in the data based on the median of the adjusted deviations, ± one median absolute deviation (mad) of the adjusted deviations: i. using the median absolute deviation to determine thresholds for peaks and dips is robust to outliers in the deviations, which do arise occasionally in the data. ii. a threshold width of one mad is relatively narrow for outlier detection, but by inspection of the data, is about right for identifying most of the peaks and dips caused by weekly cycles in test, infection, and death rates, as well as larger outliers. d. once thresholds are calculated, iterate through the data points in the time series first forward in time from oldest to newest, filling in any 'dips' (data points with adjusted deviations below the lower threshold), then backward in time from newest to oldest, smoothing out any 'peaks' (data points with adjusted deviations above the upper threshold) that remain. repeat the process until all data points' adjusted deviations are within the originally calculated thresholds for the time series. i. we infer that the underlying processes generating dips and peaks are somewhat different. dips are generally the result of weekly cycles in the data, e.g. lower rates of testing or longer lags in death reporting that occur on weekends. peaks arise to some extent due to the same weekly processes, e.g. some deaths that occur on weekends only being recorded at the start of the next week. however, some peaks, especially larger ones, may result from irregular random delays in reporting, such as large batches of tests being held up due to logistical issues and then getting processed all at once. as such the smoothing procedure for dips vs. peaks is slightly different. e. the dip-filling step fills a fraction of each dip (specified as a smoothing factor) by redistributing data counts based on a multinomial draw from the subsequent few days following each dip. i. first, calculate the amount to fill based on the deviation and the smoothing factor specified, in this case . : ii. calculate the amount redistributed from each of the following few ( ) days + , + , … + , = , based on a multinomial distribution as follows: where + , + , … + are calculated as: iii. this formulation allows some redistribution from any of the subsequent few days whose adjusted deviations exceed the focal day's adjusted deviation, but with more redistribution from days with higher adjusted deviations. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint f. the peak-smoothing step similarly redistributes a fraction of each peak, specified by the smoothing factor, to the preceding several days based on another multinomial draw. i. first, calculate the amount to redistribute similarly to the dip-filling step: ii. calculate the amount redistributed to each of the preceding several ( ) iii. this formulation redistributes peaks to preceding days based on the calculated rolling mean counts of those days, on the assumption that the irregular delays that generate random spikes in counts are essentially random and equally likely to affect any given unit of data over a several-day span. as such, the probability that a unit showing up in a spike due to such delays comes from a given preceding day is simply proportional to the expected count for that day, as approximated by the rolling mean. g. by filling dips first before smoothing peaks, the combined algorithm largely addresses any peaks that are due primarily to weekly cycles during the dip-filling stage, such that remaining peaks that get smoothed tend to be the larger, irregular ones. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint table s reports two quality of fit metrics for different countries and different time series. the first four columns report mean absolute error normalized by mean (maen) and the last four report the r-squared measures. errors for cumulative infection and deaths are followed by those for the new cases and deaths (flow variables). . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint figure s shows the visualization of fit between data and simulations for all the countries in our sample. these graphs include data and model outputs for reported new cases (blue; left axis in thousands per day) and deaths (red; right axis in thousands per day) starting from the beginning of the epidemic in each country until june . figure s -comparison of data and simulation. new cases in blue (left axis, in thousands per day) and new deaths (red, right axis). . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint estimates for true cumulative cases (blue; left axis in millions) and deaths (red; right axis in thousands) across different countries up to june are reported in figure s . figure s shows the ratio of estimated excess deaths, i.e. covid- fatalities not reported as such, to reported excess deaths, i.e. deaths over historical baseline not accounted for by reported covid- deaths, for the countries for which such data are available. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint figure s -ratio of estimated excess deaths to reported excess deaths. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint figure s shows the initial reproduction number (re) occurring in each country. reproduction numbers are changing dynamically and transient dynamics may lead to larger than equilibrium numbers if maximum re values were used. we therefore use the th percentile of simulated reproduction number in this graph. also note the large credible intervals for these estimates, partly coming from changes in what is included in the th percentile (sometimes it includes the highest values and sometimes it does not), as well as the inherent uncertainty when both reproduction number and behavioral and policy responses are estimated: one can have smaller initial re and smaller response functions, or larger values for both, and stay consistent with the data. figure s -maximum reproduction number re for each country's outbreak . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint parameter estimates figure s reports most likely estimates for the vector of country-specific parameters (θi). the figure also includes % credible intervals for these parameter estimates. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint figure s -parameter estimates and % credible regions for country-specific parameters. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint figure s reports country-level projections for new cases and deaths based on the following assumptions (consistent with those reported in figure -d in the main paper). we shift both testing and contact sensitivity to perceived risks to arguably more realistic values between current ones that capture some improvements but not a completely different behavior. specifically, on july st we shift test rate to a value % between the current rates and . % per day (which increases testing in most countries and reduces it in a few). similarly, sensitivity of contacts to perceived risk is shifted to % of the way between estimated country-level values and a high value of that is. figure s -country level projections until spring . daily cases (in thousands, blue, left axis) and daily deaths (red, right axis) are graphed. . cc-by-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not certified by peer review) the copyright holder for this preprint this version posted june , . . https://doi.org/ . / . . . doi: medrxiv preprint spread of sars-cov- in the icelandic population clinical characteristics and imaging manifestations of the novel coronavirus disease (covid- ): a multi-center study in wenzhou city detection of sars-cov- in different types of clinical specimens sensitivity of chest ct for covid- : comparison to rt-pcr stability issues of rt-pcr testing of sars-cov- for hospitalized patients clinically diagnosed with covid- weather conditions and covid- transmission: estimates and projections. medrxiv clinical characteristics of coronavirus disease in china characteristics of and important lessons from the coronavirus disease (covid- ) outbreak in china: summary of a report of cases from the chinese center for disease control and prevention covid- exacerbating inequalities in the us suppression of covid- outbreak in the municipality of vo estimating the asymptomatic proportion of coronavirus disease (covid- ) cases on board the diamond princess cruise ship universal screening for sars-cov- in women admitted for delivery incubation period and other epidemiological characteristics of novel coronavirus infections with right truncation: a statistical analysis of publicly available case data modeling the rework cycle: capturing multiple defects per task data analysis using regression and multilevel/hierarchical models accelerating markov chain monte carlo simulation by differential evolution with self-adaptive randomized subspace sampling most equations are self-explanatory. the "[…]" notation is used to subscript variables over a set of members. for example, the subscript "rgn" is used to identify different countries. therefore [rgn] indicates that a variable is defined separately for each member of the set "rgn". other subscript ranges used in the equations are: expnt: used for numerically solving the probability of missing symptoms equation. pdim: used for setting policy levels for a few variables. priors: used for implementing the random effects estimation components. each estimated parameter is mapped into an element of this subscript to simplify vector-based calculations tststs: the test status including those confirmed ('tested') and those unconfirmed complete equations and units potential test demand from susceptible population[rgn] , positive candidates interested in testing poisson subset adj active test rate[rgn] = if then else ( time < new testing time , datatestrate[rgn] , external test rate initial( inputave[priorendoave] * ( -sw endoave ) + sw endoave * calcave activities allowed by government additional asymptomatic post detection[rgn] = weighted infected post detection gate[rgn] * additional asymptomatic relative to symptomatic[rgn] / ( + additional asymptomatic relative to symptomatic additional asymptomatic relative to symptomatic[rgn] = zidz ( total asymptomatic fraction net[rgn] -exp ( -covid acuity[rgn] ) , -total asymptomatic fraction net all recovery[rgn] = recovery of confirmed[rgn] + recovery of untested[rgn] + sum ( hospital discharges expected positive poisson covid patients[rgn] + sqrt ( expected positive poisson covid patients[rgn] ^ + * effective hospital capacity[rgn] * effective hospital capacity[rgn] ) ) / ( * effective hospital capacity allocated fration noncovid hospitalized[rgn] = smoothi ( allocated fraction covid hospitalized = min ( maxalp , ialp * alpr = min ( , talp * alpr[rgn] ) units: dmnl ) alpr area of region[rgn] = get vdf constants(constant data file average acuity of positively tested[rgn] * xidz ( ( -probability of missing acuity signal at hospitals[rgn,tested] * fraction poisson not hospitalized[rgn,tested] ^ ) , -fraction poisson not hospitalized average acuity of untested poisson subset[rgn] * ( -probability of missing acuity signal at hospitals[rgn,notest] * fraction poisson not hospitalized[rgn,notest] ^ ) , -fraction poisson not hospitalized average acuity not hospitalized[rgn,notest] = zidz ( average acuity not hospitalized poisson[rgn,notest] * infectious not tested or in hospitals poisson average acuity not hospitalized[rgn,tested] = average acuity not hospitalized poisson average acuity not hospitalized poisson[rgn,tested] = max ( , probability of missing acuity signal at hospitals[rgn,tested] * average acuity of positively tested[rgn] * fraction poisson not hospitalized probability of missing acuity signal at hospitals[rgn,notest] * average acuity of untested poisson subset[rgn] * fraction poisson not hospitalized -prob missing symptom[rgn] * fraction interested not tested[rgn] ^ ) , -fraction interested not tested[rgn] , * prob missing symptom average acuity of untested poisson subset[rgn] = zidz ( poisson subset reaching test gate[rgn] * covid acuity[rgn] -positive tests of infected[rgn] * average acuity of positively tested[rgn] , poisson subset not tested passing gate positive candidates interested in testing poisson subset adj[rgn] -potential test demand from susceptible population[rgn] , positive candidates interested in testing poisson subset adj base fatality rate for unit acuity base fatality rate for unit acuity net[rgn] = initial( base fatality rate for unit acuity baseerror = units: person baseline daily fraction susceptible seeking tests demographic impact on fatality relative to china[rgn] * base fatality rate for unit acuity net baseline risk of transmission by asymptomatic[rgn] = initial( baseline transmission multiplier for untested symptomatic * multiplier transmission risk for asymptomatic net baseline transmission multiplier for untested symptomatic = units: dmnl bed per square kilometer[rgn] = initial( nominal hospital capacity[rgn] / area of region beds per thousand population[rgn] = get vdf constants(constant data file zidz ( lnymix deaths of symptomatic untested[rgn] -post mortem test rate[rgn] * frac post mortem from untreated chronic death rate[rgn] = get vdf constants(constant data file chronic impact on fatality[rgn] = initial cml death frac in hosp[rgn] = xidz ( cumulative deaths at hospital cml death fraction in hospitals large enough = sum ( if then else ( cml death frac in hosp cml known death frac hosp[rgn] = xidz ( cumulative deaths at hospital cmlterrpw = units: dmnl cmltpenaltyscl = units: dmnl constant data file :is: 'covidmodelinputs -constantdata contacts relative to normal[rgn] = min ( voluntary reduction in contacts[rgn] , activities allowed by government reaching testing gate[rgn] -symptomatic infected to testing[rgn] -untested symptomatic infected to hospital excess death start count[rgn] = :na:, , if then else ( time >= excess death start count flu acuity * covid acuity relative to flu net covid acuity relative to flu net[rgn] = initial( covid acuity relative to flu total covid hospitalized[rgn] , infectious not tested or in hospitals poisson[rgn] + infectious confirmed not hospitalized[rgn] + total covid hospitalized cumulative cases[rgn] = integ( new cases[rgn] , ) units: person cumulative confirmed cases[rgn] = infectious confirmed not hospitalized[rgn] + hospitalized infectious[rgn,tested] + cumulative deaths of confirmed confirmed recovered[rgn] + cumulative recovered at hospitals cumulative death fraction cumulative deaths at hospital[rgn,tststs cumulative deaths of confirmed[rgn] = cumulative deaths at hospital[rgn,tested] + cumulative deaths of confirmed untreated cumulative deaths of confirmed untreated[rgn] = integ( deaths of confirmed cumulative deaths untested untreated cumulative fraction total cases hospitalized[rgn] = zidz ( sum ( cumulative deaths at hospital[rgn,tststs!] + cumulative recovered at hospitals[rgn,tststs!] + hospitalized infectious[rgn,tststs!] ) , cumulative cases cumulative missed death[rgn] = integ( count missed death[rgn] , ) units: person cumulative negative tests cumulative recovered at hospitals[rgn,tststs] = integ( hospital discharges cumulative recoveries[rgn] = integ( all recovery cumulative tests conducted cumulative tests data current test rate per capita dalp = . units: dmnl data excess deaths[rgn] = get vdf constants(constant data file , 'dataconstants[rgn]', ) units: person data pseudo case fatality raw: := datacmltinfection raw: := datacmltdeath raw: units: person/day raw: := dataflowinfection raw: := dataflowdeath raw: := datatestrate raw: units: person/day cumulative confirmed cases new testing time ) ) ) units: person/day datalimitfromtime = if then else ( time > max time data used , , ) units: dmnl = units: day/year death rate[rgn] = deaths of confirmed[rgn] + deaths of symptomatic untested[rgn] + sum ( hospitalized infectious deaths tested untreated resolution[rgn] * fatality rate untreated post-detection phase resolution time" * fatality rate untreated delay order = units: dmnl demographic impact on fatality relative to china[rgn] = get vdf constants(constant data file discount rate annual = . units: /year discount rate per day = initial( discount rate annual / days per year ) units: /day dread factor in risk perception dread factor in risk perception net[rgn] = if then else ( response policy time on < time , dread factor policy * response policy weight[dfcp] + ( -response policy weight[dfcp] ) * dread factor in risk perception[rgn] , dread factor in risk perception dread factor policy = units: dmnl effective hospital capacity[rgn] = nominal hospital capacity[rgn] * normalized hospital density[rgn] ^ impact of population density on hospital availability excess death end count[rgn] = get vdf constants(constant data file excess death mean frac = . units: dmnl excess death range frac = . units: dmnl zidz ( cumulative missed death[rgn] -excess death mean frac * data excess deaths[rgn] , excess death range frac * data excess deaths excess death start count[rgn] = get vdf constants(constant data file expected positive poisson covid patients[rgn] = sum ( potential hospital demand[rgn,tststs!] ) * "post-detection phase resolution time" units: person ) expnt external test rate[rgn] = population[rgn] * policy test rate utility from normal activities[rgn] / ( utility from limited activities[rgn] + utility from normal activities units: dmnl baseline fatality multiplier[rgn] * impact of treatment on fatality rate[rgn] * average acuity hospitalized baseline fatality multiplier[rgn] * average acuity not hospitalized poisson[rgn,tststs] ^ sensitivity of fatality rate to acuity net final test rate per capita[rgn] = initial( current test rate per capita[rgn] + weight max in test goal * ( max test rate per capita -current test rate per capita final time = units: day flu acuity relative to covid deaths of symptomatic untested fraction covid death in hospitals previously tested[rgn] = zidz ( hospitalized infectious deaths fraction covid hospitalized positively tested[rgn] = zidz ( hospitalized infectious fraction interested not tested[rgn] = -zidz ( total test on covid patients[rgn] , positive candidates interested in testing poisson subset fraction interseted not correctly tested[rgn] = -( -fraction interested not additional asymptomatic relative to symptomatic[rgn] / ( + additional asymptomatic relative to symptomatic fraction of fatalities screened post mortem[rgn] = indicated fraction post mortem testing[rgn] * switch for government response fraction of population hospitalized for covid[rgn] = total covid hospitalized fraction poisson not hospitalized[rgn,tested] = exp ( -average acuity of positively tested[rgn] * ( -probability of missing acuity signal at hospitals fraction poisson not hospitalized[rgn,notest] = exp ( -average acuity of untested poisson subset[rgn] * ( -probability of missing acuity signal at hospitals fraction seeking test fraction tests positive[rgn] = zidz ( positive tests of fraction tests positive data[rgn] = min ( , zidz ( dataflowinfection[rgn] , active test rate[rgn] ) ) units: dmnl ) fractional value of limited activities = . units: dmnl global cases = sum ( cumulative cases[rgn!] ) units: person global deaths = sum ( cumulative deaths[rgn!] ) units: person global deaths , global cases ) units: dmnl government response start time hazard of symptomatic infection[rgn] = infection rate[rgn] / susceptible[rgn] * ( -total asymptomatic fraction net herd immunity fraction = . units: dmnl hospital admission infectious[rgn,tststs] = hospital admits all hospital admit ratio[rgn,tststs] = xidz ( hospital admits all hospital admits all[rgn,tested] = hospital demand from tested[rgn] * allocated fraction covid hospitalized hospital admits all[rgn,notest] = hospital demand from not tested[rgn] * allocated fraction covid hospitalized poisson subset not tested passing gate[rgn] * ( -exp ( -average acuity of untested poisson subset[rgn] * ( -pmas unconfirmed for hospital demand positive tests of infected[rgn] * ( -exp ( -average acuity of positively tested[rgn] * ( -pmas confirmed for hospital demand = ( -fatality rate treated[rgn,tststs] ) * hospital outflow covid positive hospital outflow covid positive[rgn,tststs] = hospitalized infectious[rgn,tststs] / hospitalized resolution time units cumulative deaths at hospital hospitalized infectious deaths hospitalized infectious deaths[rgn,tststs] = fatality rate treated[rgn,tststs] * hospital outflow covid positive hospitalized resolution time = units: day zidz ( sum ( hospitalized infectious deaths[rgn,tststs!] ) , sum ( hospital outflow covid positive zidz ( sum ( cumulative deaths at hospital[rgn,tststs!] ) , sum ( cumulative deaths at hospital[rgn,tststs!] + cumulative recovered at hospitals units: day flu acuity * ( prob missing symptom indicated fraction post mortem testing[rgn] = fraction covid death in hospitals previously tested[rgn] ^ sensitivity post mortem testing to capacity indicated risk of life loss[rgn] = min ( , switch for government response[rgn] * perceived hazard of infection[rgn] * dread factor in risk perception net[rgn] * pseudocfr / discount rate per day ) units: dmnl symptomatic infected to testing[rgn] -untested symptomatic infected to hospital[rgn] , ) units: person ) transmission multiplier presymptomatic[rgn] + infected pre detection[rgn] * transmission multiplier pre detection[rgn] + ( additional asymptomatic post detection[rgn] + "poisson not-tested asymptomatic transmission multiplier for confirmed[rgn] + sum ( hospitalized infectious[rgn,tststs!] * transmission multiplier for hospitalized[rgn,tststs!] ) ) * reference force of infection infectious not tested or in hospitals poisson constant data file , 'dataconstants[rgn]', ) units: person ) initial time = units known death fraction in hospitals large enough = sum ( if then else ( cml known death frac hosp[rgn!] < minhspdtreshadv , , ) * advcntrs liver disease impact on fatality[rgn] = initial( ( liver disease rate liver disease rate[rgn] = get vdf constants(constant data file , 'dataconstants[rgn]', ) units: dmnl max test rate per capita = . units: /day max time data used = units: day ) maxalp = units: dmnl units: person maxrtresh = units: dmnl constant data file , 'meanchronic', ) units: dmnl constant data file , 'meanliver', ) units: dmnl constant data file , 'meanobesity', ) units: dmnl min contact fraction minadjt = units: day multiplier recent infections to test multiplier transmission risk for asymptomatic multiplier transmission risk for asymptomatic net[rgn] = initial( multiplier transmission risk for asymptomatic + alp negative test results new cases[rgn] = infection rate new testing time = units: day nominal hospital capacity[rgn] = initial( initial population[rgn] * beds per thousand population[rgn] / ) units: person normalized hospital density[rgn] = initial( bed per square kilometer[rgn] / reference hospital density ) units: dmnl not too few susceptibles = sum ( if then else ( suscfrac[rgn!] < minsusctresh , , ) ) units: dmnl sens obesity impact net infection rate[rgn] , incubation period , , delay order ) units: person/day ) onset to detection delay = units overall death fraction[rgn] = zidz ( death rate[rgn] , all recovery[rgn] ) units: dmnl patient zero arrival[rgn] = if then else ( time < patient zero arrival time patient zero arrival time units: person ) payoff = units: dmnl ) pdim : tstp,dfcp,dgtp,scup perceived hazard of infection[rgn] = ( weight on reported probability of infection[rgn] * reported hazard of infection[rgn] + ( -weight on reported probability of infection[rgn] ) * hazard of symptomatic infection indicated risk of life loss[rgn] -perceived risk of life loss[rgn] ) / if then else ( indicated risk of life loss[rgn] > perceived risk of life loss pmas confirmed for hospital demand[rgn] = ( -reference covid hospitalization fraction confirmed[rgn] ) ^ ( / average acuity of positively tested pmas confirmed for hospital demand[rgn] + ( -pmas confirmed for hospital demand[rgn] ) * untested pmas gap with tested infectious not tested or in hospitals poisson[rgn] * exp ( -average acuity not hospitalized poisson poisson subset not tested passing gate[rgn] = poisson subset reaching test gate[rgn] -positive tests of infected poisson subset reaching test gate[rgn] = reaching testing gate[rgn] / ( + additional asymptomatic relative to symptomatic policy test rate[rgn] = if then else ( time < new testing time , current test rate per capita[rgn] , final test rate per capita infected unconfirmed post-detection"[rgn] + susceptible[rgn] + recovered unconfirmed[rgn] + confirmed recovered[rgn] + infectious confirmed not hospitalized[rgn] + "pre-symptomatic infected positive candidates interested in testing poisson subset[rgn] = poisson subset reaching test gate[rgn] * fraction seeking test positive candidates interested in testing poisson subset adj[rgn] = max ( . * potential test demand from susceptible population[rgn] , positive candidates interested in testing poisson subset positive testing of infected untreated[rgn] = positive tests of infected[rgn] * fraction poisson not hospitalized positive tests of infected[rgn] = positive candidates interested in testing poisson subset[rgn] * ( -fraction interseted not correctly tested post mortem test rate[rgn] = post mortem tests total[rgn] * sensitivity of covid test units post mortem test untreated[rgn] = post mortem test rate[rgn] * frac post mortem from untreated deaths of symptomatic untested[rgn] + hospitalized infectious deaths[rgn,notest] ) * fraction of fatalities screened post mortem post mortem tests total[rgn] = min ( post mortem testing need[rgn] , active test rate[rgn] ) units: person/day hospitalized infectious[rgn,notest] / minadjt , post mortem test rate[rgn] * ( -frac post mortem from potential hospital demand[rgn,notest] = hospital demand from not tested potential hospital demand[rgn,tested] = hospital demand from recovered unconfirmed[rgn] + cumulative recovered at hospitals[rgn,notest] ) * ( baseline daily fraction susceptible seeking tests[rgn] * fraction seeking test[rgn] + multiplier recent infections to test infection rate[rgn] + patient zero arrival[rgn] -onset of symptoms[rgn] , ) units: person ) priorendoave : upadj mtrasym ) priors : upadj prob missing symptom probability of missing acuity signal at hospitals[rgn,tested] = zidz ( ln average acuity of untested poisson subset[rgn] ) + units: dmnl ) pseudocfr units: dmnl effective reproduction rate[rgn] = zidz ( infection rate[rgn] , total weighted infected population reaching testing gate realistic r = sum ( if then else ( r effective reproduction rate recovery of untested[rgn] , ) units: person ) recovery of confirmed[rgn] = tested untreated resolution[rgn] * ( -fatality rate untreated post-detection phase resolution time" ) -deaths of symptomatic untested reference covid hospitalization fraction confirmed units: person/(km*km) regionalinputs[rfi,rgn] = reference force of infection sensitivity post mortem testing to capacity baseline daily fraction susceptible seeking tests weight on reported probability of infection multiplier recent infections to test min contact fraction confirmation impact on contact impact of population density on hospital availability impact of treatment on fatality rate log ( dread factor in risk perception reference covid hospitalization fraction confirmed base fatality rate for unit acuity net covid acuity relative to flu net sensitivity of fatality rate to acuity net total asymptomatic fraction net sens obesity impact net sens chronic impact net sens liver impact net multiplier transmission risk for asymptomatic net relative risk of transmission by hospitalized = units: dmnl relative risk of transmission by presymptomatic = units: dmnl reported hazard of infection[rgn] = positive tests of infected response policy time on = units: day response policy weight[pdim] = units: dmnl ) rgn : albania saveper = units: day sens chronic impact = e- units: dmnl sens chronic impact net[rgn] = initial( sens chronic impact * ( -sw gen sens liver impact = e- units: dmnl sens liver impact net[rgn] = initial( sens liver impact * ( -sw gen sens obesity impact = e- units: dmnl sens obesity impact net[rgn] = initial( sens obesity impact * ( -sw gen senscoviduntestedadmission = units: dmnl sensitivity of contact reduction to utility sensitivity of contact reduction to utility policy * response policy weight[scup] + ( -response policy weight[scup] ) * sensitivity of contact reduction to utility sensitivity of contact reduction to utility policy = units: dmnl sensitivity of covid test = . units: dmnl sensitivity of fatality rate to acuity sensitivity of fatality rate to acuity net[rgn] = initial( sensitivity of fatality rate to acuity sensitivity post mortem testing to capacity ^ cmlterrpw ) / ( baseerror + datacmltovertime sim pseudo case fatality[rgn] = zidz ( cumulative deaths of confirmed[rgn] , cumulative confirmed cases simcmltovertime[rgn,infection] = cumulative confirmed cases post mortem test rate[rgn] + positive tests of infected post mortem test rate total simulated tests = if then else ( flowresiduals[rgn,series] = :na:, :na:, flowresiduals units: dmnl units: dmnl ) switch for government response[rgn] = if then else ( time > government response start time symptomatic fraction in poisson[rgn] = initial( -exp ( -covid acuity[rgn] ) ) units: dmnl symptomatic fraction negative symptomatic infected to testing[rgn] = positive testing of infected untreated[rgn] + hospital admission infectious testing capacity net of post mortem tests[rgn] = active test rate positive candidates interested in testing poisson subset[rgn] * symptomatic fraction in poisson[rgn] + potential test demand from susceptible population[rgn] * symptomatic fraction negative testing on living[rgn] = min ( testing capacity net of post mortem tests indicated fraction negative demand tested[rgn] * potential test demand from susceptible population[rgn] , indicated fraction negative demand tested[rgn] * potential test demand from susceptible population[rgn] + indicated fraction positive demand tested[rgn] * positive candidates interested in testing poisson subset tests per million[rgn] = cumulative tests data[rgn] / initial population time step = . units: day time to adjust testing = units: day time to downgrade risk time to downgrade risk policy * response policy weight[dgtp] + ( -response policy weight[dgtp] ) * time to downgrade risk time to downgrade risk policy = units: day time to herd immunity[rgn] = xidz ( herd immunity fraction * susceptible time to upgrade risk total asymptomatic fraction total asymptomatic fraction net[rgn] = initial( total asymptomatic fraction total covid hospitalized[rgn] = sum ( hospitalized infectious total disease duration = onset to detection delay + "post-detection phase resolution time" + incubation period units: day total simulated tests[rgn] = post mortem tests total[rgn] + testing on living total test on covid patients[rgn] = max ( , min ( positive candidates interested in testing poisson subset total to official cases simulated[rgn] = zidz ( cumulative cases[rgn] , simcmltovertime[rgn,infection] ) units: dmnl pre-symptomatic infected transmission multiplier for confirmed[rgn] = initial( baseline transmission multiplier for untested symptomatic * confirmation impact on contact transmission multiplier for hospitalized[rgn,tststs] = initial( baseline transmission multiplier for untested symptomatic * relative risk of transmission by hospitalized * if then else ( tststs = , confirmation impact on contact transmission multiplier pre detection[rgn] = initial( baseline transmission multiplier for untested symptomatic * ( -total asymptomatic fraction net[rgn] ) + total asymptomatic fraction net[rgn] * baseline risk of transmission by asymptomatic baseline transmission multiplier for untested symptomatic * relative risk of transmission by presymptomatic ) * ( -total asymptomatic fraction net[rgn] ) + total asymptomatic fraction net[rgn] * baseline risk of transmission by asymptomatic[rgn] * relative risk of transmission by presymptomatic ) units: dmnl active test rate[rgn] units: person/day ) tststs : tested untested pmas gap with tested[rgn] = ( -allocated fration noncovid hospitalized[rgn] ) ^ senscoviduntestedadmission units: dmnl untested symptomatic infected to hospital[rgn] = hospital admission infectious utility from limited activities[rgn] = exp ( sensitivity of contact reduction to utility net[rgn] * fractional value of limited activities ) units: dmnl utility from normal activities[rgn] = exp ( sensitivity of contact reduction to utility net[rgn] * ( -perceived risk of life loss voluntary reduction in contacts[rgn] = f[rgn] / f [rgn] * ( -min contact fraction[rgn] ) + min contact fraction zidz ( sum ( average acuity hospitalized[rgn,tststs!] * hospitalized infectious[rgn,tststs!] ) , sum ( hospitalized infectious weather effect on transmission weight max in test goal = units: dmnl infected unconfirmed post-detection"[rgn] + infectious confirmed not hospitalized[rgn] + sum ( hospitalized infectious[rgn,tststs!] ) * "post-detection phase resolution time" / hospitalized resolution time units spread of sars-cov- in the icelandic population clinical characteristics and imaging manifestations of the novel coronavirus disease (covid- ): a multi-center study in wenzhou city detection of sars-cov- in different types of clinical specimens sensitivity of chest ct for covid- : comparison to rt-pcr stability issues of rt-pcr testing of sars-cov- for hospitalized patients clinically diagnosed with covid- weather conditions and covid- transmission: estimates and projections. medrxiv clinical characteristics of coronavirus disease in china characteristics of and important lessons from the coronavirus disease (covid- ) outbreak in china: summary of a report of cases from the chinese center for disease control and prevention covid- exacerbating inequalities in the us estimating the infection and case fatality ratio for coronavirus disease (covid- ) using age-adjusted data from the outbreak on the diamond princess cruise ship estimating the infection fatality rate among symptomatic covid- cases in the united states. health aff (millwood) suppression of covid- outbreak in the municipality of vo estimating the asymptomatic proportion of coronavirus disease (covid- ) cases on board the diamond princess cruise ship universal screening for sars-cov- in women admitted for delivery incubation period and other epidemiological characteristics of novel coronavirus infections with right truncation: a statistical analysis of publicly available case data modeling the rework cycle: capturing multiple defects per task data analysis using regression and multilevel/hierarchical models accelerating markov chain monte carlo simulation by differential evolution with self-adaptive randomized subspace sampling an interactive web-based dashboard to track covid- in real time simulation-based estimation of the early spread of covid- in iran: actual versus confirmed cases estimates of the severity of coronavirus disease : a model-based analysis. the lancet infectious diseases serial interval of covid- among publicly reported confirmed cases serial interval of novel coronavirus (covid- ) infections an interactive web-based dashboard to track covid- in real time key: cord- -a qz tb authors: nan title: th annual meeting of the austrian society of surgery, graz, june – , date: journal: eur surg doi: . /s - - - sha: doc_id: cord_uid: a qz tb nan background. aortic valve replacement (avr) in the elderly with significant co-morbidities is associated with increased operative risk. trans-apical catheter based avr is being evaluated in a phase study. we report the initial results of the first generation equine pericardial cribrier- edwardsvalve. methods. access is through a small antero-lateral thoracotomy with direct puncture of the apex. after initial balloon valvuloplasty the ascendra delivery system is used to position the balloon mounted crimped bioprosthesis under fluoroscopic and transesophageal echo guidance in the native aortic annulus. results. high risk patients (log euroscore . ae , female and male) with a mean age of ae . years were operated. valve positioning was successful in pts (valve size in pts and size in pts) and were converted to full sternotomy and conventional valve replacement performed. deployment time was . ae . min. delivery was achieved without cardiopulmonary bypass in % of patients. however in pts cpb became necessary to treat bleeding complications. there were deaths within days ( valve related, cardiac, abdominal). operative revision was necessary in patients for bleeding and was related to the apical access in , intercostals artery , lung laceration and was diffuse in . hemodynamic evaluation showed satisfactory results in regard to aortic insufficiency (none: , minimal ) and excellent gradients (peak gradient: . ae . mmhg). conclusions. we conclude from our data that trans-apical aortic valve replacement with the cribrier-edwards bioprosthesis can be performed in high risk patients successfully. cardiopulmonary bypass may be avoided. complications may be attributed to the high risk profile of the elderly population treated in the early learning curve. excellent imaging technology in the operating room and excellent collaboration between surgeons and cardiologist as well as anesthetists appears crucial for the successful implementation of this new treatment modality. aortic valve replacement through partial upper sternotomy: a safe alternative to full sternotomy erate to good left ventricular function and without any previous cardiac surgery at our institution. we reviewed retrospectively data on patients ( males, females) who underwent avr through a partial upper sternotomy between and . mean age was . ( - ) years. mean logistic euroscore and mean peak transvalvular gradient were . ( . - . ) and . ( - ) mmhg, respectively. results. mean cross clamp time, mean bypass time and mean operation time were . ( - ) min; . ( - ) min and . ( - ) min, respectively. in patients ( . %) a conversion into full median sternotomy was necessary. patients ( . %) had to be reexplorated due to bleeding. the mean intraoperative and postoperative red blood cell transfusions were . and . , respectively. deep sternum infection occurred in patients ( . %) . mean icu and total hospital stay were . and . days, respectively. there were hospital deaths giving a perioperative mortality of . %. conclusions. avr through a partial upper sternotomy is a safe and effective technique with a similar perioperative morbidity and mortality to conventional aortic valve surgery showing superior cosmetic results. state-of-the-art : mitral valve repairminimally invasive or median sternotomy? background. more than ten years have passed since minimally invasive mitral valve surgery employing different access and different techniques has been introduced. in spite of obvious advantages acceptance by cardiac surgeons is generally low. to define its current position in clinical practice the development of our program, actual indications and results are presented. methods. minimally invasive and conventional mitral valve procedures from to were documented prospectively. indications for the minimally invasive vs. conventional approach through median sternotomy are compared. results. seventy-five patients had minimally invasive mitral valve surgery through a cm minithoracotomy. carpentier type i, ii and iiia lesions involving the posterior, anterior or both mitral leaflets were treted using carpentier repair techniques. combined procedures of the tricuspid valve, asd and modified maze operations were performed in % of cases, patients had prosthetic mitral valve replacement. patient died at home on postoperative day from unknown causes. functional results: residual mi grade : %, grade i: %, grades i-ii: . %, grade ii: . %, grade iii or iv: . reoperations after months: . in in our department % of all mitral valve repairs needing no concomitant cabg or aortic valve operations were performed minimally invasive. conclusions. more than % of mitral valve repairs can be performed minimally invasive with excellent results. as the procedure is superior concerning cosmesis, the procedure is favored by patients and referring cardiologists. at this time disadvantages are neither proven nor suspected, advantages concerning surgical complications and rehabilitation are assumed. insights from cases of remote access perfusion for minimal invasive cardiac surgery n. bonaros , t. schachner , a. Ö hlinger , o. bernecker , g. feuchtner , g. laufer , j. bonatti background. remote access perfusion (rap) is a prerequisite for performance of minimal invasive cardiac surgery on the arrested heart. during implementation several technical challenges may be encountered. in this study we assess the incidence and the influence of these challenges on the perioperative outcome and we describe clinical results in a large patients' series. methods. we retrospectively analyzed patients who underwent minimal invasive cardiac surgery (totally endoscopic coronary artery bypass grafting: , endoscopic atrial septal defect repair: , totally endoscopic mitral valve repair: ) using rap (estech: , heartport: ). intra-and postoperative parameters were analyzed according to the occurrence or not of technical challenges attributed to remote access perfusion. results. we observed no perioperative mortality and no severe complications in this patients' series. technical problems occurred in patients ( %). three patients ( %) underwent conversion to other operative method as severely atherosclerotic peripheral vessels did not allow positioning of the balloon in the ascending aorta. another patients required an additional arterial cannula in the contralateral femoral artery to ensure adequate perfusion. balloon migrations occurred in patients ( %). in cases was a cannula replacement required ( %), in four of which due to balloon rupture. in patients ( %) positioning of the balloon in the ascending aorta required the use of fluoroscopy, as this was not possible under echocardiographical guidance. patients with technical difficulties (group ) had no worse outcome than those in whom no rap-associated problems occured (group ) with the exception of longer total operative time (group : ae min group : ae min, p ¼ . ). ventilation time, intensive care unit stay and hospital stay were all similar in the study groups (p ¼ ns). a comparison between the two cannula types showed only a higher balloon pressure needed for positioning of the estech cannula vs the heartport system ( ae vs. ae , p < . ) although comparable injection volumes were used. conclusions. we conclude that technical difficulties are not rare during rap but in most of the cases can be easily managed at the cost of increased operative time. the postoperative outcome is not compromized provided that major complications are avoided. neoangiogenesis after combined transplantation of skeletal myoblasts and angiopoietic progenitors leads to increased cell engraftment and lower apoptosis rates in ischemic heart failure background. we report on a modified minimally invasive and cosmetic approach of surgical repair of atrial septal defects (asd) i with emphasis on infant patients weighing below kg. methods. from august to july , patients underwent this procedure (mmit-modified minimally invasive technique). the heart was exposed by a limited midline skin incision and partial sternotomy (newly developed sternal spreader, fa. fehling, germany), and the atrial septal defect was closed through a right atriotomy using special new aortic and dual venous cannuals. basic results were matched to those obtained from patients (st-standard technique) . results. atrial morphology was more complex in mmit pts ( overriding svcs, sinus venosus defects), nevertheless op times were accurate and similar to st pts. early extubation was forced and made possible by fast-track methods. totally, asds were directly closed, pts had patch repair. postoperatively we observed mild postpericardectomy syndroms, cholecystitis and pneumothorax requiring drainage in st pts, only pt with mild pericardial effusion was found in mmit group. retention of pericardial effusions was not a risk factor and hospital stay was also not prolonged. conclusions. this approach achieves a cosmetically superior result with newly developed but standard instrumentation and cardiopulmonary bypass techniques, without compromising exposure or using peripheral incisions even in dysmorphic, low weight congenital patients. mmit (pts) . clinical data and follow-up were collected prospectively and analyzed retrospectively. statistical data are shown as mean values and standard deviation. in larger tumors a preoperative interventional embolization was performed. postoperatively pts were seen as outpatients once per year including ultrasound control. results. of the pts with a mean age of . þ . years there were female and male pts. in pts the unilateral tumor was located on the right side, in pts on the left side. at time of diagnosis pts ( = pts ¼ %) presented with bilateral paraganglioma. histological analysis showed benign paraganglioma in pts and malignant paraganglioma in pt. after a follow-up of to months (mean: . þ . months) pts were alive and well whereas pts were lost to follow-up. duplex ultrasound gave no evidence for recurrence of npg in pts. the patient with the malignant tumor is alive and free of recurrence after years and months. the most recent patient with bilateral paraganglioma tested positive for sdh-d mutation. two brothers and sister of this patient were diagnosed with phaeochromocytoma. conclusions. more female patients were affected than male pts. in male patients there was a higher incidence of bilateral paraganglioma of the neck. long-term survival in patients after surgical removal of neck paraganglioma appears not limited. because of the possibility to identify mutations in the sdhgene (sdhd, sdhb, sdhc) further testing of patients with bilateral paraganglioma is mandatory. screening for phaechromocytoma in these pts and evaluation of patients' families is recommended. background. endarterectomy remains the treatment of choice for ica stenosis. one major complication of surgery is cni ( - %) , encouraging transfemoral stent placement for ica stenosis. the aim of this study is to evaluate a possible reduction of this complication by the use of eversion endarterectomy (eea) compared to standard patch endarterectomy. methods. prospective study design in patients treated at a tertiary university based care center. consecutive patients were enrolled into the study. age (median years, range - years), sex (male , female ), medical risk factors (smoking %, hypertension %, diabetes mellitus %) and indication for surgery (asymptomatic stenosis %) were equally distrtributed among both groups ( patients each). all patients were evaluated pre-and postoperatively for cni by an independent neurologist and ent specialist blinded for the operative procedure. results. one patient in the conventional group suffered patch rupture with consecutive stroke days postoperatively. two patients in the conventional group developed cni ( recurrent larygeal and facial nerve deficit, hypoglossal and glossopharygeal nerve deficit). after months of follow up the latter patient showed spontaneous resolution of cranial nerve symptoms. no patient developed cni after eea. conclusions. cni has been detected in % after endarterectomy of the ica in our series. symptoms of cni may be transient, but are disturbing if no clinical improvement is observed. eea requires less operative dissection in the neck compared to standard patch endarterectomy, and therefore seems to be favourable technique with regard to cni development. eea has the potential to curb the current trend toward application of endovascular surgery for ica stenosis. background. total occlusion or stenosis of the common carotid artery is rare and the indications and techniques of surgical treatment are still a matter of controversy. we demonstrate the feasibility of retrograde common carotid endarterectomy. methods. retrospective case report study. participants. in a period of fifteen years thirty-nine patients underwent retrograde endarterectomy of the common carotid artery. twenty-nine patients were males, middle age (min , max ). ten patients were females, middle age (min , max ). symptoms of brain ischemia were present in fifteen patients. retrograde endarterectomy of the common carotid artery and endarterectomy of the internal carotid artery were done together in all patients. indication for retrograde tea was a verified stenosis > % or occlusion of the common carotid artery diagnosed by duplex ultrasound and arteriography. in three patients iatrogenically dissection of the common carotid artery was seen as indication for that procedure. main measurements. postoperative early mortality, stroke rate, medium and long-term endarterectomy patency. results. in all patients who underwent that procedure there was no occurence of major complications or statistically increased mortality. the day mortality was . % ( patients). one of them died in cause of a heart attack and one because of a cerebral bleeding. there was one ipsilateral stroke ( . %) eight month after the procedure. three patients were lost to follow-up. mean follow-up was months ( to ). there were ( . %) late deaths caused by cardiovascular related problems, pneumonia and cancer. in all living patients, controlled by duplex ultrasound, no occlusion or stenosis was found. conclusions. retrograde tea can be done through only one cervical incision for common carotid artery stenosis= occlusion, for tandem lesions of the carotid arteries as well as for iatrogenic dissections of the common carotid artery. compaired to bypass grafting this technique is a faster and easier method. our retrospective study indicates a long-term patency and freedom from neurologic events. stenosis and occlusion of the proximal subclavian artery -surgical or interventional treatment? an analysis of our own patients and international studies m. tomka, a. baumann, p. konstantiniuk, t. ott, t. cohnert division of vascular surgery, department of surgery, medical university of graz, graz, austria background. seventeen percent of all supraaortic occlusions concern subclavian artery, but only % of them fulfil the clinical and angiographic qualification of steal syndrome. methods. since patients with stenosis or occlusion of the proximal subclavian artery were treated on our department. patients underwent end-to-side transposition of the subclavian into the common carotid artery; a carotid-subclavian bypass using synthetic grafts was applied to patients. surgical treatment and evaluation, complications, short and long term patency of our patients were compared to interventional techniques and international literature. results. the primary success rate of both operative techniques achieved %. -days mortality was %, -days morbidity % ( = ) in the transposition group and . % ( = ) in the bypass-group respectively. median follow-up time was months in the transposition-group vs. months in the bypass-group. only in the latter one late occlusion ( . %) was seen. conclusions. our data show a slight (not significant) favour for the transposition, which is consistent with results from other studies. concerning long term patency and infection rates the transposition of the subclavian into the common carotid artery by single incision is to be recommended first choice of treatment. avoiding synthetic grafts leads to optimal compliance. flow in natural direction and less mortality and morbidity rate are ensured. critical, because preoperative ef is predictive for long-term survival. here, we report results from a genomic study in patients with as in compensated and decompensated state and present candidate genes that could be predictive for the progression of heart failure. methods. biopsies from the lv septum of male patients (  a ae yrs) with isolated as undergoing biologic aortic valve replacement (carpentier edwards magna a + ) were harvested either from hearts with normal ef (> %, n ¼ ) or from a group with low ef ( %, n ¼ ) and served as controls. total rna was analyzed on affymetrix hg-u a genechips, which allowed to measure expression levels of more than . human gene transcripts. low level expression analysis was performed using the gc-rma algorithm and statistical significance analysis was done by bayesian t-test. class prediction was performed using the brb arraytools package (nci). results. expression levels clearly distinguished as from cad. annotation of these transcripts revealed a close correlation with the hypertrophic response and progressive fibrosis. these targets completely reflected the current understanding of key processes involved in heart failure. within a list of several ( ) as classifier genes that revealed well-known markers such as the natriuretic peptide precursors a and b and troponin i, we identified: ( ) the connective tissue growth factor ( vs. ; p < . ), known to be triggered by mechanical stress in fibroblasts; ( ) periostin ( vs. , p ¼ . ), an important matricellular component recently shown to be responsible for ventricular dilation. when specifically searching for low ef class predictors, we found potential candidates of unknown function, which were consistently expressed at a higher level only in as with ef < %: ( ) the pom and zp fusion gene ( vs. , p ¼ . ) and ( ) the transcription factor ets variant ( vs. , p ¼ . ). conclusions. in this study we could clearly identify patients with cad from those with as by the help of gene expression profiling. moreover, we were able to identify gene expression signatures that could be predictive for the progression of heart failure. background. despite tremendous advances in immunosuppressive therapy acute rejection still remains a problem following solid organ transplantation. proteome analysis has emerged as a valuable tool for the study of large scale protein expression profiles and biomarker detection. here we applied this novel technology to identify specific biomarkers for acute cardiac allograft rejection. methods. cardiac allografts of c bl= mice were placed into fully mhc-mismatched c h=he recipients. syngeneic transplants served as controls. protein expression analysis was performed using fluorescence two-dimensional difference gel electrophoresis ( d-dige) on day six post transplant. spots of interest were subjected to nanospray ionization tandem mass spectrometry (ms=ms) for protein identification. expression of selected proteins was confirmed by western blot analysis. results. median graft survival of untreated hearts was . ae . days whereas all syngeneic animals showed indefinite graft survival > days. analysis of the d-dige gels revealed a total of protein spots that were significantly regulated by more than . -fold during acute rejection when compared to syngeneic controls. spots with highest altered regulation identified with ms=ms were derived from coronin a, vimentin, protein disulfide isomerase a precursor, skeletal muscle lim-protein , aconitate hydratase, and fumarate hydratase. peroxiredoxin and pyruvate kinase isozyme m were selected for further analyses. western blotting and immunohistochemistry showed significantly higher expression of these proteins during acute rejection compared to syngeneic grafts. conclusions. this study demonstrates that proteomics is a powerful method to detect biomarkers of acute cardiac allograft rejection. identified proteins like peroxiredoxin and pyruvate kinase isozyme m represent novel indicators of acute rejection and may become useful surrogate markers for monitoring the alloimmune response. impact of endothelin-a receptor blockade on myocardial gene expression post mi w. dietl , g. mitterer , m. bauer , k. trescher , w. schmidt , b. k. podesser background. despite promising experimental results of endothelin-a (et-a) receptor blockade in treatment of heart failure (hf), clinical trials failed to confirm these findings. in order to elucidate this discrepancy, we decided to evaluate the impact of et blockade on myocardial gene expression (ge) post myocardial infarction (mi). methods. mi was induced in male sprague-dawley rats using lad ligation. three days post mi, rats were randomized to receive either tbc -na or placebo and to survive either or days. sham-operated rats served as control group. prior scarification, rats underwent echocardiography. following excision, hearts were analyzed morphometrically. rna was extracted from non-infarcted areas of the lv. targets for quantification were identified using affymetrix gene chip + technology and subsequently quantified by real time pcr. results. et-a blockade did not influence morphology or hemodynamics on day , while it significantly improved both parameters on day . in contrast, ge analysis revealed that the majority of mi-induced changes in ge occur early after mi, with the majority of genes returning to baseline after days. five days of et-a blockade resulted in an attenuated expression of mi-induced transcripts (e.g. tnc, spp , sparc, mmp ) involved in post-mi remodeling. conclusions. apparently, endothelin receptor blockade influences early post-mi remodeling. this data adds further evidence that timing is crucial in et therapy post mi: administered to early, myocardial wound healing is disturbed and lv function deteriorates. given in time, excessive ventricular remodeling is attenuated and lv function improves. identification of sex-specific targets in experimental heart failure m. bauer , g. mitterer , w. dietl , k. trescher , w. m. schmidt , b. k. podesser background. sex-specific differences have been reported in ischemic heart failure. the aim of the present study was to screen for diferentially expressed genes in experimental ischemic heart-failure using genechip + technology. methods. mi was induced in male (n ¼ ) and female (n ¼ ) sprague-dawley rats by ligation of the lad. and days post-mi, surviving animals were sacrificed and samples of the non infarcted free wall gained to perform transcription analysis. sham-operated males (n ¼ ) and females (n ¼ ) served as control. extracted rna of animals per group was pooled and affimetrix genechip + technology was used to screen for differentially expressed targets. genechips + were analyzed using the mas . algorithm and the following rules employed comparing mi vs. corresponding sham to identify sex-specific targets: ) increase in expression in one sex and a decrease in the other, ) increase in expression one sex and absent in the other, ) decrease in expression one sex and present in the other. results. our strategy revealed targets differentially expressed. of these targets were expressed differentially on day only, on day , only one target was expressed differentially on both and days post-mi. of this targets were selected for further analysis including: keratins, caspase- , aldehydoxidase- , cdkn- a and triadin and will be evaluated using rt-pcr. conclusions. ) there are sex-specific targets in post-mi gene expression. ) this targets can be identified using gene-chip as screening tool. bilirubin rinse suppresses early mapk activation in cardiac ischemia-reperfusion injury r. Ö llinger , p. kogler , f. bösch , c. koidl , r. sucher , m. thomas , j. troppmair , f. bach , r. margreiter background. heme oxygenase- (ho- ) expression is crucial in preventing ischemia reperfusion injury (iri). bilirubin, a product of heme catabolism by ho- at least in part accounts for the protective effects mediated by ho- , however, the mechanisms by which bilirubin mediates these effects remain to be elucidated and strategies to apply the bile pigment are needed. mitogen activated protein kinases (mapk) are activated upon stress and play an important role in the early phase of iri. we hypothesized that in a mouse model of heart transplantation, a brief rinse with bilirubin of the graft before reperfusion would affect mapk activation. methods. isogenic c bl= hearts (n ¼ =group and time point) were harvested, stored in uw solution at degrees for h and then rinsed with bilirubin at . mm or ringer lactctate as a control before anastomosis. anastomosis time was kept constant at min by using a cuff-technique, subsequently thereafter perfusion was restored. samples were collected at various times. western blot analysis was carried out for total (t) and phosphorylated (p) forms of akt, erk = , jnk = and p mapk. p=t ratio was quantified by imagej and statistically analyzed using anova. results. after anastomosis and before any reperfusion phosphorylation of erk and p mapk was increased when compared to h of ischemia allone. this was not seen when grafts were rinsed with bilirubin. further, at min after reperfusion, phosphorylation of all mapks being investigated was dramatically increased when compared to the non-reperfused isografts. at this time point, bilirubin significantly inhibited phosphorylation of erk and jnk (p < . ) as well as p -mapk and akt (p < . ). conclusions. bilirubin rinse of mouse cardiac isografts causes a dramatic decrease of mapk activation associated with the proinflammatory response to the stress of iri. bilirubin rinse of allografts before implantation might be a potent aproach to avoid early organ dysfunction. improvement of myocardial protection by a selective endothelin-a receptor antagonist added to cardioplegia in failing hearts background. ischemia=reperfusion (i=r) injury due to cardioplegic arrest is a problem in patients with reduced lv function. we investigated the effect of chronic versus acute administration of the selective endothelin-a receptor antagonist tbc- na during i=r in failing hearts. methods. male sprague-dawley rats underwent coronary ligation. three days post infarction group (n ¼ ) was administered tbc- na continuously with their drinking water, groups and received placebo. seven weeks post infarction hearts were evaluated on a blood perfused working heart during ischemia and reperfusion. in group (n ¼ ) tbc- na and in group placebo was added to cardioplegia during ischemia. results. at similar infarct size postischemic recovery of cardiac output (group : ae %, group : ae % vs. placebo: ae %; p < . ) and external heart work (group : ae %, group : ae % vs. placebo: ae %, p < . ) group was significantly enhanced in both tbc- na treated groups while recovery of coronary flow was only improved in group (group : ae % vs. group : ae %, placebo: ae %, p < . ). evaluation of blood gas measurements showed enhanced myocardial oxygen delivery and consumption with acute tbc- na therapy. in addition high energy phos-phates were significantly higher and transmission electron microscopy revealed less ultrastructural damage only under acute tbc- na administration. conclusions. acute endothelin-a receptor blockade is superior to chronic blockade in attenuating i=r injury in failing hearts. ultrastructural and biochemical evaluation indicate an improvement in capillary perfusion by acute tbc- na administration during reperfusion resulting in a better cardiac function post ischemia. therefore acute andothelin-a receptor blockade might be an interesting option for patients with heart failure undergoing cardiac surgery. background. except in inguinal hernia with strong fascia, treatment of these hernias requires a reinforcement of the inguinal wall. different methods have been established based on different approaches and different degree of reinforcement: partially (lichtenstein, rutkow=robbins) or totally (rives, stoppa, wantz, tipp, tep, tapp) . in danish and swedish hernia register a surprisingly high number of female (especially femoral) recurrencies were found emphasizing the problem, as mainly lichtenstein procedure was performed. increasing knowledge of reasons of fascial insufficiency give further hints towards using a total reinforcement of the inguinal region. among these procedures the transinguinal preperitoneal hernioplasty with a memory-ring armed polyprolylene patch (polysoft patch tm ) is new and promising. methods. between . . and . . inguinal hernias in patients have been treated by tipp with polysoft patch tm ( bassum-suhlingen, idstein). operation and patient data were recorded prospective. we operated male and female hernias. after - month patients were interviewed with a standard questionaire. = patients ( . %) answered. results. medial, lateral, combined and femoral hernias were done. = recurrent hernias ( . %), = incarcerated hernias ( . %). intraoperative complications: = ( . %). postoperative complications have been bleedings, infection, wound dissections. haematomas= seromas we have seen preperitoneal in cases, subcutaneous in cases. re-operations and punctions have been performed. a hydrocele has been seen in = cases, an ileoinguinal syndrome we have noted in cases (no resection has been performed). under intention of a preperitoneal repair, patients have got another treatment: lichtenstein, rutkow and shouldice procedures. in = patients ( . %) the positioning of the patch was difficult mainly due to very small or fatty anatomy. longterm results ( year postoperative): . % had some pain or heavy pain, . % had occasional pain and . % had little or some movement problems. there was recurrent femoral hernia ( mm hole with fat; months post op), only one patch has been removed because of strong pain in riding or sitting in low seats. conclusions. tipp is a safe procedure which fulfills the requirement of a total reinforcement of the inguinal wall. the memory-ring armed polypropylene patch covers the inguinal region and makes the procedure easier compared to the predecessors (e.g. wantz). results. there were primary and recurrent hernias. in cases local and in spinal anaesthesia was used. no intraoperative complications occured, all meshes could be placed easily. patient had local pain for weeks. at followup patients were symptom-free, had paresthesia and infra-inguinal swelling. conclusions. parietene mesh is easy and fast to use and gives satisfying early results. since part of the mesh will resorb within year long-term results will have to be awaited. light versus heavy meshes for laparoscopic inguinal hernia repair -a biomechanical study the incidence of recurrence, first of all, has been lowered by a laparoscopic technique. methods. during the last years we have operated on patients for incisional and abdominal wall hernias. results. there were men and women with a mean age of . years. we applied an intraperitoneal onlay meshtechnique (ipom) by a laparoscopic way. twenty-three patients had an abdominal incisional hernia, an umbilical hernia, an epigastric hernia, a trocar-hernia and one patient a spigelian-hernia. the diameter of abdominal wall defects was - cm. in patients a parietex composite-mesh has been used, in a proceed-mesh, in a bard composix-mesh and in one patient two  cm timeshes. mesh-size was  cm to  cm . hernia sacs were left in place, hernia contents, mostly omentum, were replaced into the abdominal cavity. meshes were fixed using endo-clips in patients, tacks in and the salute fixation-system in patients. postoperative follow-up includes a control at week, month and year postoperatively. there were no problems during operation. patients were discharged on the second postoperative day. after a mean follow-up of . months ( - months) two patients have a hernia recurrence, three patients had local pain for one month and one patient had an umbilical infection, which could be managed without the removal of the mesh. conclusions. laparoscopic incisional and abdominal hernia repair has a low incidence of complications and shows a rapid postoperative recovery of patients. long-term follow-up is necessary for evaluation of mesh reactions with regard to infection as well as to adhesion formation with the intestine. background. the fixation of hiatal meshes with perforating devices, such as tacks or sutures, can be associated with potentially life threatening complications [ ] . fibrin sealant (fs, tissucol, baxter biosciences, vienna, austria) is successfully used for atraumatic mesh fixation in inguinal and incisional hernia repair [ , ] . the rationale of this study was to test the potential of fs fixation of hiatal meshes in pigs. methods. in general anaesthesia, domestic pigs were subjected to laparotomy and designated meshes (ti-sure, gfe, nuremberg, germany) were implanted at the hiatus. the titanized polypropylene material was found to be favorable in combination with fs in a previous study [ ] . meshes were sealed with ml of fs, which was applied with a spray system. the observation period was weeks in all animals in order to assess tissue integration after the fs was already degraded. results. all meshes showed excellent integration and no sign of dislocation or perforation into the neighbouring organs. histology was used to confirm. conclusions. fs for hiatal mesh fixation provides a safe and effective alternative to perforating fixation devices in an animal model of repair. background. we aimed to assess the incidence for esophageal, cardiac and gastric cancer. methods. annual incidence data and age adjusted rates for the years to were obtained from statistics austria which operates the nationwide austrian cancer registry. according to icd-o- (international classification of diseases for oncology, third edition), the following categories were considered: esophageal squamous cell carcinoma (c , - ), esophageal adenocarcinoma, (c , - ), cardiac adenocarcinoma (c . , - ) and non cardiac gastric adenocarcinoma (with known and unknown subsite, c . [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] , esophageal and gastric tumors with ill-defined histology and death certificate only (dco)-cases. results. annual incidence of esophageal squamous cell carcinoma increased from cases in to in , peaked in ( cases) towards ( ) , declined towards and cases in and , respectively. from to adenocarcinoma of the esophagus increased fold ( vs. ). the number of unspecified epithelial neoplasms of the esophagus remained stable ( - cases). dco cases, comprising no histological information, were stable from (n ¼ ) to (n ¼ ), decreased until ( cases) and increased in ( cases). from to adenocarcinoma of the cardia increased . fold ( vs. ) and remained rather stable with about cases per year until ; cases were registered. non cardiac gastric adenocarcinomas and gastric adenocarcinomas with ill-defined location decreased . fold ( vs. ) and . fold ( vs. ), respectively. the numbers of histologically unspecified cases of malignant cardia tumors and dco cases remained rather stable (unspecified: in and in ; dco: cases in and cases in ) . gender distribution shows an increase of esophageal squamous cell carcinoma in females (male:female : ¼ . in to : ¼ . in ) and esophageal adenocarcinoma (male: female ratio vs. ; : vs. : ; ratio . vs. . ) and cardiac adenocarcinoma for males ( : vs. : ; ratio . vs. . ) . age adjusted rates per . population of non-cardiac gastric carcinomas decreases for both sexes (data not shown). we observed an increase of esophageal squamous cell carcinoma in females and esophageal and cardiac adenocarcinoma for males and a decrease of non-cardiac gastric carcinomas for both sexes. endoscopic versus open esophageal resection: a prospective case-control study within the learning curve background. esophageal resection for cancer is followed by remarkable morbidity. endoscopic surgery has been established to reduce the physical burden. in our institution endoscopic and open esophageal resection is performed transthoracally (tse) or transmediastinally (lstme) as appropriate. we aimed to compare outcomes of case matched open and minimal access esophageal resection by a case-control analysis. methods. endoscopic minimal access esophageal resection (mae) has been performed since (mae). a retrospective case control study including patients (prospectively collected data) who underwent mae (tse, , lstme, ) has been undertaken with matched (pairs matched for sex, age, tumour type and type of resection) historical open (oe) cases operated between and (transthoracic esophageal resection tte, , transmediastinal esophageal resection tme, ). groups were comparable regarding age, sex distribution, tumour type (as consequence of matching) as well as regarding tumour stage and comorbidities. results. forty patients (males, ; females, ; mean age ae yrs) were included in the study. there were adenocarcinomas and squamous cell cancers. patients had neoadjuvant chemotherapy (fu=cis). duration of surgery, number of resected lymphnodes, duration of intubation, icu stay and hospital stay was vs. min (p ¼ . ), vs. (p ¼ . ), . vs. . days (p ¼ . ), vs. days (p ¼ . ) and . vs. days (p ¼ . ) in the mae and oe group, respectively. due to preexistent anemia = mae patients received erythrocyte substitution preoperatively, = patients of the oe group needed erythrocyte subsitution perioperatively. = and = patients underwent reoperation for a complication in the mae and oe group. overall surgical morbidity was % ( = ) and % ( = ). postoperative pneumonia was observed in = and = among mae and oe patients. conclusions. during the learning curve duration of mae is significantly longer when compared with oe. morbidity was reduced, icu and hospital stay were significantly shorter after mae, regarding duration of postoperative ventilation there was a trend towards mae. oncological quality was comparable between groups with respect to the number of resected lymph nodes. the need for blood substitution and reoperation was higher in open esophageal resection. even during initial establishment mae seems advantageous for the patient in this case-control study. randomised trials are still missing. does the route of gastric pull-up influence the oxygen supply of the anastomosis? background. microcirculation and oxygen supply at the level of oesophagogastric anastomosis following oesophagectomy are among the crucial factors determining anastomotic healing. methods. twenty-nine patients (mean age . yrs) were evaluated during oesophagectomy and on the intensive care unit by inserting a micro-probe (licox) and continuously recording the interstitial po of the tubulated stomach in the anastomotic region. two different surgical procedures were applied: group ( = ) had gastric pull-up via a retrosternal, group ( = ) via an orthotopic route. the interstitial po values were averaged over specific consecutive periods: intraoperatively after ligation of the short gastric vessels, after ligation of the left gastric artery, after forming the conduit and after gastric pull-up. postoperative measurements were recorded during intubation, while breathing oxygen by mask or by nose delivery, respectively and finally while breathing air. results. before ligating the left gastric artery the interstitial po -levels were significantly higher (mean . mmhg) than after ligation (mean . mmhg; p < . ). comparing the retrosternal ( . mmhg) versus the orthotopic pull-up route ( . mmhg) a significant difference (p < . ) in favour of the orthotopic route could be found after gastric pull-up as well as during each postoperative measurement period. no differences could be detected when comparing the various oxygen supply systems. conclusions. these data suggest that the oxygen supply at the anastomosis of the pedicled gastric conduit reaches higher levels after orthotopic than following retrosternal gastric pull-up. p tailored therapy for esophageal cancerpilot study in reported -year survival rates of % in this group. factors identifying this subgroup of responders and selecting optimal drugs for non responders could dramatically enhance treatment efficacy. several studies suggest that mutations in the p gene may induce drug resistance especially for agents whose effect is based on apoptosis induction, like cisplatin. methods. in order to test the hypothesis that the p genotype is predictive for chemotherapy response, a prospective study was conducted. thirty-eight patients with potentially respectable esophageal cancer were evaluated for the relation between p genotype and response to two different neoadjuvant treatments. p gene mutations were assessed by complete direct sequencing of dna extracted from diagnostic biopsies. response to neoadjuvant chemotherapy was assessed pathohistologically in the surgical specimen. results. twenty squamous cell carcinoma and adenocarcinoma were included. overall the p mutation rate was % ( = ), with % for squamous cell and % for adenocarcinomas, respectively. patients received cis= fu (cisplatin mg=m d -fu mg=m d - , q , cycles), received docetaxel ( mg=m , q , cycles). the overall response rate was % ( = ). patients with p mutation did not respond to cis= -fu ( = ), while all mutant patients responded to docetaxel ( = ). the overall response to p adapted neoadjuvant therapy was %. p adapted treatment was associated with a significant survival advantage (p ¼ . ) after a median follow up of . months. conclusions. a prospective randomized trial was initiated to test the interaction between the predictive marker p and response to respectively. a new method of anti-ischemic graft protection in retrosternal colon esophagoplasty a. albokrinov , a. pereyaslov , r. kovalskiy lviv children's regional clinic hospital, lviv, ukraine; lviv d. halytsky national medical university, lviv, ukraine background. retrosternal colon esophagoplasty is the operation of choice in infants with esophageal atresia with great diastasis. although complications are rare, some cases of graft ischemia are registered. epidural block have beneficial effect on splanchnic blood flow because of drug sympathectomy. methods. we retrospectively analyzed rate of graft ischemia in infants with retrosternal colon esophagoplasty and conventional postoperative course with anticoagulants and antiaggregants (group , n ¼ ). group , n ¼ was investigated prospectively with preoperative catheterization of epidural space (th -th level, lost of resistance test, g size) and . % bupivacaine administration in daily dose of . mg=kg every h. the rest of therapy was equal in all patients. graft status was determined visually. gut motility was considered to restore when stool have been obtained. results. rate of graft ischemia was significantly lower in group then in group ( vs , p < . ). besides this, gut motility restoration in group was significantly earlier ( . ae . vs . ae . days, p < . ). conclusions. epidural block with local anesthetic is an effective method of anti-ischemic protection of neo-esophagus and powerful instrument in gut motility restoration. background. atrial fibrillation (af) is often associated with thromboembolic complications, heart failure and stroke; in addition an increase in mortality, even with adequate anticoagulation, is observed. the maze operation is an effective and accepted method to terminate af, nevertheless the risk for intraoperative bleeding is increased compared to left atrial ablation procedures using variable energy sources. left atrial ablation is an alternative method to convert af into sinus rhythm (sr), as with this procedure linear lesions connecting the four pulmonary veins and the posterior mitral annulus are created with microwave or high frequency technique. methods. a consecutive series of patients ( females, males; age a, range - a) underwent ablation during various cardiac surgical procedures between and . endocardial ablation using either microwave or radiofrequency energy was performed times ( . %) and epicardial with microwave energy in five cases ( . %) . preoperative parameters: ejection fraction . % ae . %; diameter left atrium . ae . mm. forty-one patients underwent mitral valve repair (mvp), patients obtained mitral valve replacement (mvr), patients received aortic valve replacement (avr), patients underwent coronary bypass surgery (cabg) and patients had combined valve surgery (others). results. others combined valve replacement: mvr þ tvp, mvr þ avr; af atrial fibrillation; aflut atrial flutter; pm pace maker no intraoperative or postoperative complications related to the concomitant ablation procedure were observed. one patient died because of multiple organ failure. after a mean follow up period of months ae patients remained in sr ( . %), patients into af ( . %), patients changed rhythm into atrial flutter ( . %) and one patient required a pace maker ( . %). conclusions. in approximately two thirds of patients left atrial ablation is effective in restoration and maintenance of sr in patients with structural heart disease and af. this method represents a valid alternative to the maze technique, reducing myocardial ischemic time and risk of bleeding. midterm results are promising; however for determination of a long term benefit especially regarding thromboembolic events, a higher number of patients and a longer follow up period are desired. background. the study aim was to evaluate the efficacy and outcome of endocardial and epicardial atrial fibrillation (af) ablation in patients undergoing heart surgery. methods. between february and december , patients (mean age years, range - ) underwent left atrial ablation combined with other type of cardiac surgery. in patients endocardial left atrial ablation using a unipolar radiofrequency device (cardioblate tm , medtronic, usa) was performed, mainly in combination with mitral valve (mv) surgery ( mv repair, mv replacements) . in patients epicardial pulmonary vein isolation using microwave energy (flex tm , guidant-boston scientific, usa) was done during aortic valve replacement ( ) and bypass grafting ( ) . indication for atrial ablation was permanent af in all patients. endocardial ablation was performed during extracorporal circulation (ecc) with a mean time of min ( - ), epicardial ablation before ecc with a mean ablation time of min ( ) ( ) ( ) ( ) ( ) ( ) . % of the patients ( ) received amiodarone postoperatively, % ( ) betablocker. patients underwent epicardial cardioversion with synchrus tm (guidant, usa) wires postoperatively. results. the overall mortality was . % ( patients during mv replacement due to posterior bleeding) complications were posterior rupture ( ) , lco with the need of intraaortoc pallon pump ( ), resternotomies for bleeding, and and ( %) pacemaker implantations ( . %). there were no ablation procedure related complications. sinus rhythm (sr) was achieved in % after operation, % at discharge and % at the month follow up. a nodal rhythm was found in % after operation, % at discharge and in % after months. patients developed atrial flutter ( in the group of endocardial and in the group of epicardial ablation). af persisted in % of the patients at month. conclusions. af ablation combined with cardiac surgery is safe and effective. recurrent af is frequent during the first three months after ablation also under therapy with antiarryhthmic drugs. background. patient-prosthesis mismatch is a frequent cause of high postoperative mortality and gradients. the objective of this study was to determine whether mismatch can be predicted at the time of operation. methods. indices used to predict mismatch were valve size, indexed internal geometric area and projected indexed effective orifice area (eoa) calculated at the time of operation, and results were compared with the indexed eoa measured by doppler echocardiography after operation in patients. results. the sensitivity and specificity of these indices to detect mismatch, defined as a postoperative indexed eoa of . cṁ =ṁ or less, were % and % for valve size % and % for indexed internal geometric area, and % an % for projected indexed eoa. conclusions. the projected indexed effective orifice area calculated at the time of operation accurately predicts mismatch, where as valve size and indexed internal geometric area cannot be used for this purpose. excellent long-term results after emergency cardiac surgery d. martin, a. yates, h. mächler, l. salaymeh, d. dacar, b. rigler division of cardiac surgery, department of surgery, medical university of graz, graz, austria background. data from all adult patients undergoing emergency heart surgery between and at the division of cardiac surgery, medical university of graz, austria, were reviewed retrospectively. methods. data were stored in a local cardiac surgery database. the registery included all relevant patients data and euro-score. no patient was lost to follow-up. a series of relevant perioperative data were collected. recorded complications were use of the intra-aortic balloon pump (iabp) and low cardiac output syndrome. hospital and late mortality data were collected from the austrian national populations register. multivariante analysis was performed to determinate predictors for cardiac related death. results. between and patients underwent emergency cardiac surgery at our institution. there were men ( . %) and women ( . %) with an average age of . years. coronary artery bypass was performed in . %, . % combined valve and bypass, . % valve, . % aortic dissection and . % had other procedures. eighty-seven patients ( . %) had a postoperative low cardiac output syndrome. the intra-aortic balloon pump was used in patients ( . %). variables identifying as high risk for perioperative cardiac related death were diagnosis other then coronary artery disease, patients with iabp and high catecho-lamine demand. there were no postoperative wound infections. eighteen patients ( . %) had excessive postoperative bleeding and ( . %) required a late re-intervention. hospital mortality was . % and the late mortality after years was . %. conclusions. the hospital mortality was higher in the emergency group but there was no difference in the long-term results for elective and emergency surgery. early mortality was significant higher in patients operated for other reason than coronary artery disease. background. acute renal failure is a serious adverse event after cardiac surgery, which is associated with high perioperative mortality and prolonged hospitalization. the aim of our study was to evaluate pre-and intraoperative risk factors for the development of acute renal failure requiring hemofiltration (arf) after cardiac surgery. the influence of different methods for evaluation of renal function was investigated. methods. from = through = , patients underwent cardiac surgery at our institution. patients developed arf ( . %), patients suffering from chronic end-stage renal insufficiency were excluded from the study. patient characteristics and operative variables were analyzed. a multivariate logistic regression analysis was performed to determine risk factors for arf. results. patients, who developed arf, were older (p < . , or: . ) as compared to patients who did not develop arf. furthermore, diabetes mellitus (p ¼ . , or: . ), peripheral artery disease (p ¼ . , or . ), cardiogenic shock (p ¼ . , or: . ), congestive heart failure (p ¼ . , or: . ) und emergent surgery (p ¼ . , or: . ) were predictive for development of arf. preoperative serum creatinine was not predictive for arf (p ¼ . , or: . ). classification of preoperative serum creatinine into normal ( . mg=dl), slightly elevated ( . to < mg=dl) and severely elevated (! mg=dl), reveals a correlation with the development of for severely elevated creatinine levels (p ¼ . , or: . ), as well as for slightly elevated levels (p ¼ . , or: . ). calculation of creatinine clearance mwith the cockcroft-gault formula demonstrated a strong correlation with the development of arf (p ¼ . , or: . ). calculation of creatinine clearance with the mdrd formula, however, failed to reveal any correlation with (p ¼ . , or: . ). conclusions. our data indicate, that advanced age, diabetes mellitus, peripheral artery disease, cardiogenic shock and congestive heart failure, as well as emergent surgery independently predict arf after cardiac surgery. even slightly elevated creatinine levels are a risk for the development of arf after cardiac surgery. calculation of creatinine clearance with the cockcroft-gault formula is more suitable for preoperative risk stratifica-tion as compared to calculation of creatinine clearance with the mdrd formula. background. the matricellular protein tenascin-c (tn-c) induces production of matrix metalloproteinases (mmps), inhibits cellular adhesion and mediates cellular deadhesion. these effects are crucial in the dynamic process of cardiac remodeling. it has been reported that tn-c expression is up-regulated in ventricular remodeling following myocardial infarction (mi) in the border zone between scar tissue and non-infarcted area. we analysed the expression of tn-c in the post mi infarcted and non-infarcted area after the treatment with the selective endothelin a (et a )-receptor antagonist tbc -na. blockade of the et a -receptor decreases cell proliferation, lv hypertrophy, and secretion of pro-inflammatory mediators. methods. mi was induced in male sprague dawley rats by lad ligation. three days post mi, rats were randomised to receive either the endothelin antagonist tbc -na (n ¼ ) or placebo (n ¼ ), as control rats were sham-operated without lad ligation (n ¼ ). after days hearts were harvested and tissue samples from scar, peri-infarct and free wall were analysed by western blot using a monoclonal antibody specifically recognizing the egf like domain of tn-c. tissue was homogenized in urea buffer and protein samples were subjected to % polyacrylamide gel sds-page, transferred on to a membrane and immunostained with the anti-tn-c monoclonal antibody and antimouse alkaline phosphatase antibody. additionally on day and echocardiography and morphological analysis were performed to assess the effect of tbc -na therapy on cardiac function. results. infarct size was comparable in all groups (et agroup . ae . %, placebo group . ae . %). during early remodelling on day , in the placebo group, tn-c was upregulated in scar tissue. in contrast, in the et a -group, tn-c was down regulated in scar tissue. on day post mi, no differences were seen in the tn-c levels. echocardiography showed significant improvements in hemodynamics in the et a -group in contrast to controls. conclusions. from these results, we can conclude that ( ) endothelin-a receptor blockade attenuates the development of heart failure post mi, ( ) reduction of tn-c expression seems to have a positive effect on postinfarct remodeling, ( ) tn-c regulation is influenced by et a -blockade and ( ) that tn-c is a marker for lv remodeling after myocardial infarction. background. diabetes is a risk factor for neurocognitive and neurological complications after cardiopulmonary bypass. we sought to determine if temperature management during cardiopulmonary bypass (cpb) affects the incidence of neurocognitive and neurological complications in diabetic patients. methods. in this prospective randomized study, we measured the effects of mild hypothermic ( c, n ¼ ) vs. normothermic ( c, n ¼ ) cpb on neurocognitive function. all patients underwent elective coronary artery bypass grafting (mean age . ae . years, mean es . ae . ) . neurocognitive function was objectively measured by objective p auditory-evoked potentials before surgery, week and months after surgery, respectively. clinical data and outcome were monitored. results. p evoked potentials were comparable between patients operated with mild hypothermic ( ae ms) and normothermic cpb ( ae ms) before the operation (p ¼ . ). patients operated with mild hypothermic cpb, showed marked impairment ( ¼ prolongation) of p evoked potentials week ( ae ms; p< . ) and months ( ae ms; p ¼ . ) after surgery. in contrast, patients operated with normothermic cpb did not show impairment of p evoked potentials week ( ae ms; p ¼ . ) and months ( ae ms; p ¼ . ) after surgery. group comparison revealed prolonged p peak latencies in the patient group operated with mild hypothermic cpb (p ¼ . ) week after surgery. four months postoperatively, no difference between the two groups could be shown (p ¼ . ). operative data and adverse events were comparable between the two groups. conclusions. normothermic cardiopulmonary bypass reduces neurocognitive deficit in diabetic patients undergoing elective coronary artery bypass grafting. ergebnisse. die paclitaxelbehandlung führte zu einer dosisabhängigen reduktion der intimalen hyperplasie im vergleich zur kontrollgruppe (p ¼ . bei mmolar, p ¼ . bei mmolar, p ¼ . bei mmolar und p ¼ . bei mmolar). in der elasticafärbung fanden sich sowohl in der media als auch in der intima meist nur vereinzelte elastische fasern, wohingegen sich in der trichromfärbung in der media insbesondere subintimal reichlich kollagene fasern fanden, die intima selbst jedoch hierfür negativ blieb. immunhistochemisch zeigte sich die media und die intima praktisch vollständig positiv für sma. bei der desmin-färbung fand sich die media ebenfalls fast durchgehend spezifisch positiv für desmin, die intima hingegen färbte sich hierfür jedoch in unterschiedlichen ausmaß ( - %) an. in der proliferationsfärbung mit ki zeigten sich vorwiegend die längsverlaufenden muskelfasern der media stark proliferierend, wohingegen der subintimale mediabereich und die intima nur vereinzelt ki positiv war. schlussfolgerungen. paclitaxelbehandlung reduziert die intimale hyperplasie in der vena saphena im organkulturmodell. elastische fasern, kollagenfasern, sma positive und desminpositive zellen sowie ki positive (proliferierende) zellen weisen unterschiedliche bevorzugte lokalisationen innerhalb der gefässwand auf. heat shock proteins = = = = = = = = = a and s proteasome in on-versus off-pump coronary artery bypass graft patients background. heat shock protein (hsp) , hsp , hsp , hsp and s immune-proteasome are known chaperons. they play a prominent role in housekeeping processes, in the intracellular regulation of the immune system and in apoptosis. serum levels of circulating chaperons are not known in patients undergoing the on-versus off-pump coronary artery bypass graft (cabg) procedure. methods. forty patients were prospectively included in the study (on-vs. off-pump cabg, each n ¼ ). elisa technique was utilized to detect levels of soluble hsp , , , and s immune-proteasome in serum samples. results. on-pump cabg procedure is associated with an increased leakage of heat shock proteins into the vascular bed when compared to off-pump cabg technique. these differences were highly significant for hsp , and min after initiation of cardiopulmonary bypass (cpb) (all, p< . ). concentrations of soluble s immune-proteasome were increased h after operation in on-and off-pump cabg patients (p < . ) and correlated significantly with the serum content of hsps , and at min after initiation of cpb (p < . ). conclusions. our data evidence the spillage of chaperons, normally intracellular restricted proteins, into the systemic circulation. as these proteins are related to immunomodulatory and apoptotic processes, we conclude that the innate immune system is more activated in on-pump as compared with off-pump cabg patients. however, the precise immunological consequence and interpretation requires further investigations. background. in the treatment of ruptured abdominal aortic aneurysm (raaa) the results of open graft replacement (ogr) remained constant but discouraging over the last four decades. provided patients have a suitable vascular anatomy, elective endovascular abdominal aortic aneurysm repair (evar) turned out to be less invasive than ogr and led to improved perioperative mortality especially for patients with severe comorbidities. thus, it is reasonable to assume that endovascular treatment should improve the results of patients with risk factors heavily impaired by rupture of their aaa. the purpose of this study was to test whether the use of both endovascular and open repair for raaa was able to improve results. methods. retrospective analysis of a consecutive series of patients presenting with raaa from october, , until july, . observation period was divided in two periods of months, respectively. during the first period patients were treated by ogr exclusively. period two started with the availability of an evar protocol to treat raaa, according to which patients received open repair while patients underwent evar. kaplan-meier survival estimates were calculated and possible differences were analyzed by log-rank and wilcoxon-test. results. kaplan-meier survival estimates revealed a statistically significant reduction in overall postoperative mortality following the introduction of evar in (p < . ). ninety day overall mortality was reduced from . % during period one to . % during the second period (p < . ). especially survival of patients older than . years was improved ( % vs. . %, p < . ). in parallel there was a significant reduction of the day mortality rate after ogr from . % (i.e. overall mortality) to % (p < . ). conclusions. offering both evar and ogr in the treatment of raaa led to significant improvement of postoperative survival. especially older patients seem to benefit from the less invasive endoluminal technique. fast track concept for infrarenal aortic aneurysm repair c. senekowitsch , r. schwarz , a. assadian , w. hartmann , g. hagmü ller background. the aim and main benefit of the fast track concept in surgery are increased patient comfort and reduced perioperative morbidity and mortality. in abdominal surgery, this concept has proven efficient. we present our experience of fast track aortic surgery. methods. retrospective analysis of prospectively collected data. since initiating this method of perioperative patient management in january , patients underwent infrarenal aortic reconstructions for aortic aneurisms applying the fast track concept. this comprises of modified nutrition and fluid management, anaesthesiological management and a special retroperitoneal access allowing aggressive postoperative mobilisation. results. patients were included in the study, their mean age was years (range - years) none of the patients had surgical complications, no mortality was observed. the icu days were reduced to for all patients. the mean hospital stay was days (range - days). conclusions. hospital stay and icu days could be reduced dramatically compared to standard therapy at our institution. this new concept in aortic surgery is a valid alternative to evar for selected patients. aneurysma der a. lienalis: fallbericht über interventionell-chirurgisches management e. gü nen, j. demmer, c. groß department of cardio-thoracic and visceral surgery, general hospital linz, linz, austria aneurysms of splenic arteries are seldom ( . % of all aneurysms). nevertheless they are disastrous when ruptured since they bleed into the free abdominal cavity without any means of self-tamponade. occurrence of splenic aneurysms is related to female gender, esp. after multiple gravidities. these aneurysms are usually symptomless and tend to rupture during labour pains. this fact explains the reports on ruptured splenic aneurysms in young women from developing countries whereas in western countries most findings are incidental in routine imaging scans. we report on a yo female from chechnya with a huge splenic aneurysm and splenomegaly. she complained about chronic fatigue and nausea. splenomegaly and a pulsating growth in the mid epigastrium were palpable in the physical examination. the wbc blood counts showed severe pancytopenia. ct-scan revealed a calcified aneurysm (Ø cm) of a tortous splenic artery and an enlarged spleen ( cm). we decided to occlude the origin of splenic artery interventionally and and to perform a ''lone splenectomy'' leaving the unperfused aneurysm in situ. the intervention achieved total angiographic occlusion. however during surgery the aneurysm was still under pulsatile pressure. the pulsation ceased on surgical ligation of the proximal splenic artery. subsequently the splenectomy was performed. the patient recovered without surgery related complications. a year after surgery she has normal blood counts. the aneurysm has not shrunk but shifted to left to adopt the space left over by the spleen. background. the transilluminated powered phlebectomy (tipp; trivex + , smith and nephew) was introduced in the year in our hospital. trivex + is a procedure for minimal invasive vein surgery including an illuminator device, a powered vein resector, a light source and a controll unit. the use of tumescent solution allows hydrodissection and facilitates ablation (rotating inner blade of vein resector combined with suction). methods. in an retrospective study we report patients ( males and females; mean age . years; limbs) treated with this technology during the years and . we used a combination stripping the saphenus veins ( ligations of the sapheno-femoral junction, ligations of the popliteo-femoral junction) or ligations of perforantes ( ) if necessary according to sonography. twenty-seven patients underwent single trivex + treatment. . % were done in general anaesthesia. a follow up is proposed to all patients after to months ( patients, . %). results. the average time of surgical treatment was . min, with single trivex . min. the trivex + procedure for one single leg took about min. the average stay was . days. regarding to postoperative complications one patient experienced laceration of the femoral vein ( . %), one profound bleeding caused a revision the same day ( . %). patients developed lokal wound infektion within the first weeks ( . %). during the follow up period complications like swelling ( ), seroma ( ), brown scars ( ), nerve injury=numbness ( ), haematoma ( ) occured. there was no skin perforation, no phlebitis, none of our patients died. conclusions. according to these results the trivex + procedure seems to be a quick and safe treatment for minimal invasive removement of superficial varicosities. background. this randomized, patient and observer blinded trial compared early postoperative outcomes in saphenectomy with either a new bipolar coagulating electric vein stripper (evs) or invagination stripping. methods. the primary outcome was pain at rest and following physical stress (climbing stairs), as assessed by a visual analog scale (vas) h after surgery. secondary outcomes included haematoma formation (diagnosed and measured by ultrasound), duration of postoperative compression, and disability. quality of life was assessed by a disease-specific chronic lower limb venous insufficiency questionnaire (civiq), and the generic short form (sf- ). results. two hundred patients were assigned to three vascular centers, with patients randomized to the evs and to the conventional arm. there were no complications or conversions. pain at rest averaged . in the evs and . in the conventional group (mean difference . , per cent confidence interval (c.i.) . to . , p < . ). following physical stress, mean ratings were . and . (mean difference . , per cent c.i. . to . , p < ). no measurable haematoma was found in the stripping canal of the evs group, while in the conventional arm patients had haematomas within this region (risk difference per cent, per cent c.i. to percent). duration of compression therapy was significantly decreased in the evs group (mean difference days, per cent c.i. to days). in the evs group, patients returned to work after week and after weeks, compared to and patients in group . civiq and sf- ratings favored the evs. conclusions. the evs is a safe instrument. it is effective in avoiding painful haematomas following saphenectomy, reduces recovery time and improves patients' ratings of quality of life. elt in combination with pin stripping in the treatment of epifascial truncal veins a. j. flor background. in the treatment of varicose truncal veins, endolaser treatment has widely been accepted as the method of choice. yet laser treatment -in particular in epifascial veins -may result in a painful contraction. we examine the functional and cosmetic results as well as the patients' comfort, combining elt and pin stripping in patients with epifascial truncal veins. methods. preoperative evaluation is carried out by color duplex sonography. emphasis is laid on patients with a partially epifascial course of the greater saphenous vein (gsv). following extensive evaluation and information of the patient, the decision is made to use endolaser treatment (biolitec, nm) in combination with pin-stripping (retriever-pin by oesch, salzmann medico). a guiding wire is inserted, duplex-controlled or through miniphlebectomy, into the gsv at the point of perforation through the fascia. a laser fiber is then positioned at the sapheno-femoral junction, and laser energy is applied to the intrafascial part of the truncal vein ( - j=cm) depending on the vein diameter. the epifascial part of the vein is then retrieved by the pin stripper. results. until now the combination of endolaser plus pin stripping has been applied in patients. following observation periods of to months, endolaser treatment provides an occlusion rate of %. skin incisions need not be wider than mm. crossectomy can be avoided. patients tend to have more hematomas in the pin-stripped region, yet a hardened, sometimes brown coloured and often painful strand -as often seen in patients treated by endolaser only -can be avoided thereby. conclusions. in about - % of the cases, an epifascial position of the gsv might been detected by duplex sonography. in cases of epifascial course of the truncal vein, decision to use elt treatment alone should be considered critically. in such cases, endolaser treatment combined with pin stripping should result in a higher degree of patient comfort, apparently providing an optimal solution for a minimally-invasive approach. endovenous laser treatment with the nm laser system; years of experience, follow-up of over veins k. freudenthaler background. chronic venous insufficiency is a common desease. the aims are to offer a minimal invasive alternative to traditional surgery such as crossectomia and stripping with less pain for the patient and a short reconvalescence. methods. since years over patients with more than veins have been treated by evlt, by grand saphenous veins a valve repair by venocuff ii was possible. only patients have been treated by traditional crossectomia and stripping. usually the grand and the short saphenous vein as well as the acessoria vein, insufficient perforaters and the giacomini anastomosis are treated by evlt. the treatment is done in general or in local anaesthesia and monitored by permanent ultrasound control. in no case a surgical crossektomia was necessary. after treatment the patient has to wear a compression stocking for two weeks dayover and should not lift heavy duties. results. after treatment the results are verified by ultrasound. the patients are controlled after one week, month and yearly thereafter. the total sucess rate is % in all cases (complete resorption of the treated vein). there were no complications like pulmonal embolia, infects or skin burns. conclusions. the evlt is a very safe treatment of chronic venous insufficiency and offers a minimal invasive alternative to traditional surgery such as crossektomia and stripping. Ö sterreichische gesellschaft fü r chirurgische forschung: die zukunft hat schon begonnen -bedeutung der molekularen biologie fü r diagnostik, prognose und therapie in der gastrointestinalen chirurgie proteomic profiling of the secretome of human liver endothelial cells (hlec) background. liver endothelial cells play significant roles in the physiology and pathology of the liver. they are not simply barrier cells regulating the traffic of blood components to the parenchyma and vice versa, but highly specialized cells with complex roles, including scavenger functions and regulation of inflammation, leukocyte recruitment and host immune responses to pathogens and shaping of the microenvironment by secretion of functionally relevant proteins. thus, investigation of the functional and physiological properties of lec is critical in understanding liver biology and pathophysiology. the aim of this study was to establish techniques to isolate and cultivate human liver endothelial cells and to obtain a protein profile of the secretome of quiescent and vegf-activated hlec. methods. hlec from unaffected tissue of resected liver segments from patients undergoing surgery for liver tumours were isolated using magnetic beads coated with anti-cd -antibodies. cells where cultured in medium ebm- (mv) supplemented with vegf, bfgf, igf, egf, heparin, endothelial cell growth supplement and % fetal calf serum. expression of endothelial cell surface markers cd , cd , cd e, cd and podoplanin as well as fibroblast marker cd was investigated by facs. hlec where starved for h in protein free medium and activated with vegf for further h. supernatants were collected and subjected to shotgun proteomics. human umbilical vein endothelial cells (huvec) served as a control. results. isolated cells where morphologically similar to huvec. % of cells where positive for cd , cd , and cd . % expressed cd . % of cd positive cells where positive for podoplanin. expression of cd was low, but consistent. cd e was induced in % of cells and expression of cd was upregulated fold after h activation with tnf-. shotgun proteomics of the secretome revealed a distinct differ-ence in the secretion pattern of several functionally relevant proteins compared to huvec. conclusions. our results point towards a significant and persistent difference in secretion patterns of functionally relevant proteins between hlec and other endothelial cells both in quiescence and after vegf activation. these findings may lead to a better understanding of physiology of the liver. finally, this study demonstrates the suitability of magnetic bead isolation in combination with in vitro cell culture and proteomics for investigation of hlec functions. hypermethylation of sfrp gene in stool dna test: a future technology in colorectal cancer screening w. zhang, w. hohenberger, k. matzel background. stool dna test is considered as a future technology in screening for colorectal cancer (crc). both genetic and epigenetic changes in shed cells from gastrointestinal tumours into stool could be detected. epigenetic hypermethylation can result in transcriptional silencing of tumour suppressor genes and is considered to be a key event of sporadic colorectal carcinogenesis. sfrp is a tumour suppressor protein that contains a domain similar to one of wnt-receptor proteins and inhibits wnt-receptor binding to its signal transduction molecules. detection of hypermethylation of sfrp gene in human dna isolated from stools might provide a novel strategy for the detection of sporadic crc. our study aims to prove the methylation status of sfrp gene in stool samples, and compare the dna methylation status before and after neoadjuvant radiochemotherapy. methods. to explore the feasibility of stool dna test, fecal samples were obtained from crc patients (crc patients post neoadjuvant radiochemotherapy n ¼ ). twenty fecal samples were obtained from patients without evidence of gastrointestinal disease or neoplasia. isolated genomic dna from stool was modified with sodium bisulfite and analyzed by specific pcr for methylation of sfrp promoter. results. with stool dna test we were able to detect the hypermethylation in the promoter region of sfrp gene in the fecal dna from colorectal cancer patients (p ¼ . ). sensitivity was %, specificity was %. methylation status of sfrp gene was significantly changed after neoadjuvant radiochemotherapy (p ¼ . ). conclusions. the hypermethylation of sfrp gene in the stool dna test has a high sensitivity and specificity for crc and may be valuable for screening purposes, especial for the sporadic crc. compared with current colorectal cancer screening methods, stool dna test is more patient-friendly, non-invasive, more sensitive and specific. the cost-effectiveness of screening may also be improved by using single dna stool test with one sensitive dna marker. the methylation status of sfrp seems to be changed after neoadjuvant radiochemotherapy, which may open new fields for crc research. summarized this new diagnostic tool may yield ben-efits in earlier detection and in the design of better antitumour interventions. background. although the function and interaction partners of the glycoprotein dickkopf- (dkk- ) still remain unclear, gene expression of dkk- has been shown to be upregulated in tumor endothelium of colorectal cancer. for the first time, we analyzed expression of dkk- protein and its potential as a marker of neoangiogenesis in colorectal cancer. methods. we utilized tissue microarrays (tmas) to evaluate dkk- protein expression in microvessels of colorectal cancer samples from patients, in microvessels of adjacent tissue samples from the same patients compared to normal colorectal mucosa tma samples. a second microarray section was stained with cd to quantify neoangiogenesis by defining the microvessel count. results. out of cancer samples with cd positive microvessels, . % were dkk- positive in all microvessels. these samples showed a significantly higher mean microvessel count ( . vessels) than dkk- negative samples ( . vessels; p ¼ . ). dkk- protein expression increased with rising numbers of microvessels per sample (p < . ). out of cd positive adjacent tissue samples, % were dkk- positive. these samples also had a higher mean microvessel count ( . vessles) than dkk- negative samples ( . vessels; p < . ). similar to colorectal cancer tissue, dkk- expression in non-cancerous adjacent tissue increased with rising numbers of microvessels (p < . ). in contrast, all microvessels in normal colorectal mucosa samples demonstrated a negative staining reaction for dkk- . univariate analysis of several clinicopathologic variables in correlation to dkk- expression revealed significant differences in tumor site (colon vs. rectum; p ¼ . ) and mean age (p ¼ . ). survival analysis according to kaplan-meier method showed a statistical trend toward a higher diseasefree survival for patients with dkk- negative samples (p ¼ . ). conclusions. our study demonstrates for the first time that microvessels of colorectal cancer and adjacent non-cancerous tissue are identical concerning dkk- protein expression, but distinct from normal colorectal mucosa. therefore, dkk- can be considered as a putative pro-angiogenic protein in the process of neovascularization, may have the potential to serve as a marker for neoangiogenesis, and may represent a target structure for novel therapeutic approaches. nevertheless, it is mandatory to further confirm these findings using normal tissue sections. background. we have developed the first genetically engineered oncolytic influenza a viruses (ns deletion viruses), which replicate and lyse cancer cells but are apathogenic in normal tissue. infection of influenza a viruses are usually highly dependent on the presence of a serine-like protease (i.e. trypsin), which cleaves the viral entry protein, the hemagglutinin. cancer cells are known to endogenously produce proteases. methods. we here investigate, whether colon cancer associated proteases support lytic growth of the oncolytic influenza viruses in those cells. results. ns deletion viruses grew to high titers in the colon cancer cell lines caco or ht- independent of the addition of trypsin. correspondingly, viral infection rate, cleavage of the hemagglutinin and virus-induced cytopathic was not compromised by the lack of trypsin in these cell lines. zymogram analysis indicated that the caco and ht- associated protease is not trypsin itself but trypsin unrelated. conclusions. the specific activation of the influenza a virus in colon cancer cell lines suggests an effective use of this virus for oncolysis in colon cancer in vivo. background. for decades the bile pigment bilirubin has been considered a toxic waste product of heme catabolism. however, serveral clinical studies show an inverse correlation between elevated plasma bilirubin levels in healthy individuals and the incidence=mortality of colorectal cancer. based on these findings, we hypothesized that bilirubin and its precursor biliverdin may suppress tumor cell growth in vitro and inhibit tumor progression in vivo. methods. in vitro hrt- colon cancer cells were treated with bilirubin at various concentrations or pbs as a control. a casy cell counter was used for proliferation assays. cell cycle progression and apoptosis were analyzed by facs. western blot analysis was carried out using antibodies directed against p , rb, p , parp- and caspase as well as total and phosphorylated forms of erk, mek and akt. further, cells were treated with pharmacological inhibitors of mek and pi -kinase in presence or absence of bilirubin. in vivo, nude mice bearing hrt- tumors were treated with bilirubin i.p. at mg=kg=day or pbs as a control. tumor size was measured using a caliper. statistical analysis was performed using anova. results. bilirubin significantly inhibited proliferation of hrt- colon cancer cells in a dose dependent manner. this mainly was mediated by induction of g =g cell cycle arrest and apoptosis through strong activation of akt, mek and erk resulting in overexpression of the cell cycle regulators p , p , hypophosphorylation of rb as well as an increase of parp- and caspase cleavage. the antiproliferative effects were dependent on akt and erk activation, in that inhibition of upstream pi -kinase and mek reversed the effects observed under bilirubin treatment. in vivo, bilirubin dramatically decreased tumor growth by % (sd ae . ) when compared to the control. conclusions. bilirubin is a potent inhibitor of hrt- colon cancer cell growth in vitro and in vivo, presumably by modulating mitogen activated protein kinase signaling pathways resulting in cell cycle arrest and apoptosis. background. tetrahydrobiopterin (bh ) is an essential cofactor for nitric oxide synthases and thus a critical determinant of no production. recently we have shown that bh depletion contributes to ischemia reperfusion injury (iri) after pancreas transplantation. here we analysed the therapeutic potential of bh supplementation during organ procurement and the early post-transplant period. methods. murine cervical heterotopic pancreas transplantation was performed with a modified no-touch technique. pancreatic grafts were subjected to h prolonged cold ischemia time (cit) and different treatment regiments: untreated (i), bh mm to perfusion solution (ii), bh mg=kg i.m. at reperfusion (iii). nontransplanted animals served as controls (iv). intravital fluorescence microscopy was used for analysis of graft microcirculation by means of functional capillary density (fcd) and capillary diameters (cd) after h of reperfusion. quantitative assessment of inflammatory responses (mononuclear infiltration) and endothelial disintegration (edema formation) was done by histology (h&e) and peroxynitrite formation assessed by nitrotyrosineimmunostaining. results. fcd was significantly reduced after prolonged cit, paralleled by an increased peroxynitrite formation, when compared with controls (all p < . ). microcirculatory changes correlated significantly with intragraft peroxynitrite generation (spearman: r ¼ À . ; p < . ). pancreatic grafts treated with bh either during retrieval (ii) or systemically (iii) displayed markedly higher values of fcd (p < . ) and abrogated nitrotyrosine staining (p < . ). cd were not significant different in any of the investigated groups. histologic evaluation showed increased inflammation, interstitial edema, hemorrhage, acinar vacuolization and focal areas of necrosis after h cit in group i, which could be diminished by both bh treatment regiments (p < . ). conclusions. bh treatment significantly reduces postischemic deterioration of microcirculation as well as histologic damage and might be a promising novel strategy in attenuating iri in clinical pancreas transplantation. methods. forty-seven biopsies obtained from the endoscopic esophagogastric junction in patients ( females, males; age ; range - years) with symptoms of gastroesophageal reflux disease were processed for histopathology and immunohistochemistry. biopsies were stained with routine h&e and immunofluoresence staining using an antibody directed against hydrogen=potassium atpase (h þ =k þ atpase beta) (pot) for detection of parietal cells (pot ¼ monoclonal clonal mouse igg antibody, g clone, dilution : ; product numberma affinity bioreagents d- hamburg, germany). pot detects the beta-subunit of hydrogen= potassium atpase in bovine, human, canine, porcine, rabbit, mouse, ferret, and rat tissues. histopathology in h&e stained sections was conducted according to the paull-chandrasoma classification of columnar lined esophagus (cle) including oxyntocardiac (ocm; mucus and parietal cells) and cardiac mucosa (cm; mucus cells only) with or without intestinal metaplasia (im ¼ barrett esophagus). out of biopsies also contained gastric oxyntic mucosa (mucus, parietal and chief cells) and served as controls (these biopsies contained both cle and om). the detection of parietal cells in h&e and pot-staining was compared. results. h&e staining showed that out of patients had cm with im (barrett esophagus), had cm without im. a total of slices was investigated ( h&e pot). pot stained the cytoplasma of parietal cells indicating the presence of biologic active acid pump. in biopsies parietal cells were only detected in pot stained slices, whereas in the other biopsies parietal cells were detected by both h&e and pot-staining. parietal cells were detected in all biopsies containing gastric om. therefore pot did not significantly increase the parietal cell detection rate in cle compared to h&e staining. conclusions. detection of ocm within biopsies from columnar lined esophagus is not significantly increased by the use of an antibody directed against h þ =k þ atpase. h&e staining is adequate for detection of parietal cells within cle. lymphovascular invasion and lymphangiogenesis in adenocarcinoma of the esophagus: impact on patient survival e. rieder , s. schoppmann , s. kandutsch , f. wrba , f. langer , c. neumayer , p. panhofer , g. prager , j. zacherl background. a special feature of esophageal cancer is its early lymphatic spread in comparison with other cancers of the gastrointestinal tract. due to the discovery of specific markers for lymphatic endothelium, selective staining of lymphatic vessels has become possible. in recent studies the prognostic value of peritumoral lymphangiogenesis and lymphovascular invasion in various human malignancies has been shown. tumor-associated macrophages (tam), expressing the lymphoangiogenic growth factor vegf-c, were shown to be related to tumor-associated lymphangiogenesis, lymphovascular invasion and lymph-node metastasis. aim of this study was to assess tumor-associated lymphangiogenesis as well as the role of tams in a cohort of adenocarcinoma of the esophagus. methods. fourty formalin-fixed, paraffin-embedded surgical specimens of patients (age range: - ) presenting with adenocarcinoma of the esophagus at the university hospital of vienna were included into this study. specimens were stained with antibodies against podoplanin, vegf-c and anti-cd . semiquantitative measurements of lymphatic microvessel density (lmvd) and lymphatic vessel invasion (lvi) were carried out. results. it could be demonstrated that lymphangiogenesis occurs in barrett adenocarcinoma and is correlated with lvi. statistical analysis revealed that lvi is associated with disease-free (p ¼ . ) as well as overal survival (p ¼ . ) of patients with barrett carcinoma. furthermore over-expression of vegf-c was seen in barrett carcinomas and vegf-c expressing tams were detected peritumoral and therfore may play a role in lymphogenic metastasis of esophagus carcinoma. conclusions. these preliminary data demonstrate that lymphovascular invasion as well as tumor-induced lymphangiogenesis is associated with patient survival in barrett adenocarcinoma and anti-lymphangiogenic therapies might be a beneficial approach. background. the role of tissue-inhibitor of metalloproteinases- (timp- ) in cancer progression is still unclear. although timp- is an important inhibitor of metastasis-associated proteases, it is often correlated with a bad prognosis. in an animal model, elevated levels of timp- , achieved by adenoviral-gene-transfer, led to induction of hepatocyte growth factor (hgf)-signaling and expression of several metastasispromoting genes in the liver, representing a host-microenvironment with increased susceptibility to a challenge of tumor cells. we examined the expression of candidate metastasis-promoting factors by qrt-pcr. methods. liver-tissues of consecutive metastatic colorectal cancer patients ( males, females; mean age, . ae . y) were obtained. to determine timp- -associated gene expression signatures in the normal liver tissue, specimen were harvested from zones greater than cm away from visible liver metastases and analyzed by quantitative-real-time-pcr (qrt-pcr, taqman + -low-density-arrays) of metastasis-associated genes. results. human liver tissue with elevated timp- levels was associated with an identical pro-metastatic gene expression signatures as previously identified in the animal model, namely increased expression of hgf, pcna, upa, upar, tpa, matriptase, mmp- , mmp- , adam- , cathepsin g, and neutrophil elastase. conclusions. we reveal here for the first time a ubiquitous (human and mouse=different tumor types) timp- -related gene expression profile. this profile, consisting of metastasis-promoting genes, can explain the correlation between tumor aggressiveness in cancer patients and increased levels of timp- and demonstrates the impact of the host microenvironment on its susceptibility to invading tumor cells. this concept is important for future considerations of cancer therapies. Ö gth -herz: varia rv-lv depolarisation-interval as a predictor of longterm-survival of crt-patients: a criteria for intraoperative quality control t. schwierz , s. winter , h. nesser , r. fü gger surgical department, elisabethinen-hospital, linz, austria; cardiological department, elisabethinen-hospital, linz, austria background. for cardial resynchronisation therapy the left-ventricular lead should stimulate the most delayed myocadial area. we introduce a method, established in or dayly routine, for intraoperative verification of the hemodynamically best lead-position. methods. the electrical distance between rv-and lv-lead we verify by measurement of the time between rv-pacing and lv-sensing (depolarisation-intervall). by a cox regressionmodel we analized the data of patients with regard to possible predictors of patients-survival following crt. results. significant predictors of survival were the age of patients (p ¼ . ), lvef (p ¼ . ), biventricularly stimulated qrs-duration (p ¼ . ), reduction of qrs-duration under biventricular stimulation in relation to rv-pacing in % (p ¼ . ), depolarisation-intervall (p ¼ . ), depolarisation-intervall in relation to qrs-duration under rv-pacing in % (p ¼ . ). conclusions. out of the predictors significant for the patients-survival following crt only the depolarisation-intervall can be influenced activly during the implantation procedure. the rv-and lv-lead should be implanted so that the depolarsation-intervall is as long as possible. ideally, the depolarisation-intervall covers the entire qrs-duration under rv-pacing. in that case the lv-lead stimulates exactly the latest depolarisized myocardial area. the fibrin derived peptide b-beta - ameliorates ischemia-reperfusion injury in a rat heart transplant model background. the purpose of this study was to evaluate the protective effect of the fibrin-derived peptide b-beta - on ischemia=reperfusion injury in a rat cardiac transplant model. methods. lew hearts were flushed with chilled ( - c) custodiol preservation solution and either transplanted immediately or stored for or h in the same solution and then transplanted into syngeneic recipients. b-beta - was given i.v. at a dose of . mg immediately after transplantation or added to the preservation solution prior to harvest. at h and d, graft function was assessed and hearts were retrieved for morphological evaluation. at time of harvest, serum samples were collected for troponin level analysis. results. hearts transplanted immediately or after h of cold ischemia did neither show any morphological damage at h nor at days. in contrast, h of ischemia resulted in severe myocardial ischemia associated with an inflammatory response at h. lesions further progressed at days. administration of b-beta - resulted in a significant amelioration of myocardial necrosis together with a diminished inflammatory response. a protective effect towards myocyte damage was further underlined by reduced troponin levels in groups receiving b-beta - . acute cellular rejection after cardiac transplantation -is there a way to reduce the number of biopsies? background. acute cellular rejection significantly contributes to mortality and morbidity after cardiac transplantation (htx). routine endomyocardial biopsies (embs) are performed to early detect and treat cellular rejection. although emb can be performed with little risk, a number of potentially fatal complications are inherent in the procedure. the aim of our investigation was to evaluate the incidence of acute cellular rejection after heart tranplantation and to evaluate possibilities to reduce the number of embs. methods. patients underwent cardiac transplantation from january through december at our institution. the mean age of the patients was . ae . years. . % were female. indication for htx was icmp in . %, dcmp in . % und others in . % of the cases. according to our institutional standard, patients underwent emb weekly during the first month after htx, biweekly during months and , monthly up to month , once in month , and . a total of embs were investigated over a follow-up period of months after htx. results. the majority of embs showed no signs of rejection ( . % ishlt ). mild signs of rejection without therapeutical consequence (ishlt ia) were found in . % of embs. rejection ishlt ib was found in . % of the evaluated embs. the incidence was . % during the first month after htx, in the second month . %, in rd month . %, in th and th month . %, in th and th month . %, and from the th month . %. a moderate rejection (ishlt ii) was detected in . %. during the first month after htx, the incidence was . %, during nd month . %, during rd month . %, in th und th month . %, in th und th month . % and from the th month . %. more severe rejections were rare ( x ishlt iiia ¼ . %, x ishlt iiib ¼ . %) and occurred in month , , and . conclusions. severe cellular rejection after htx is seldom. mild to moderate rejection episodes, however, occur more frequently. in contrast to the traditional emb schedules, rejection hardly ever occurs during the first weeks after htx. most rejection episodes are observed between the second and seventh month after htx. afterwards, the incidence of rejection lowers again. based on these findings, the number of routine embs can safely be reduced, especially during the first weeks after htx. background. renal dysfunction has consistently been one of the greatest risks for mortality with the use of left ventricular assist devices (lvad). we aimed to determine the impact of renal function on survival and time-dependent changes in renal function after lvad implantation. methods. we retrospectively reviewed patients with advanced heart failure (mean age . ae . yrs, % male, % ischemic cardiomyopathy) who received lvad implantation as a bridge to transplant therapy from to . renal function was assessed using the modification of diet in renal disease (mdrd)-derived glomerular filtration rates (gfr). patients were divided into groups based on renal function pre-lvad implantation; group : normal (gfr ! ml=min= . m , n ¼ ), group : impaired (gfr < ml=min= . m , n ¼ ) renal function. results. patient survival was comparable between the groups. the , and -month kaplan-meier estimate of survival was . %, . % and . % for group and . %, . and % for group (p ¼ . ). gfr paired sample analysis in group showed an early increase in gfr from preimplantation ( . ae . ml=min= . m ) to postoperative day (pod) ( . ae . ml=min= . m ; p ¼ . ). there was no increase in gfr from pre-implantation ( . ae . ml= min= . m ) to heart transplantation ( . ae . ml=min= . m ; p ¼ . ). in contrast, gfr paired sample analysis in group showed an early increase in gfr from pre-implantation ( . ae ml=min= . m ) to pod ( . ae . ml= min= . m ; p< . ), and a further increase in gfr from pod ( . ae ml=min= . m ) to pod ( . ae . ml= min= . m ; p ¼ . ). there was a significant increase in gfr from pre-implantation ( . ae . ml=min= . m ) to heart transplantation ( . ae . ml=min= . m ; p< . ). conclusions. renal function improves rapidly after lvad implantation. renal dysfunction does not adversely affect outcome after lvad implantation. methods. bed interdisciplinary paediatric intensive care unit, university hospital. patients. patients after open heart surgery; prospective controlled study. group a received mg tc=kg bodyweight pre-and post operation and h after operation, whereas group b received mg tc=kg bw in the same period. drug levels and routine laboratory parameters were investigated daily in the picu. the aim of both groups was a tc serum concentration of - mg=l by adapting dosage after h. results. in group a tc concentration were . ae . and . ae . mg=l after and h, in group b . ae . and . ae . mg=l (p < . both), respectively. crp values were in group a ae . mg=l and ae . mg=l and in group b ae . mg=l and ae . mg=l (p < . and p < . ), respectively. there were no differences in physiological scoring. conclusions. to achieve drug levels of tc higher than mg=l during the first h after surgery, the higher dosage of mg=kg bw had to be administered initially. the high tc dosage was well tolerated and was associated with significantly lower crp in the first two days. background. the fontan operation eliminates the systemic hypoxemia and ventricular volume overload in congenital patients with single ventricle physiology. retrospectively, we report on our longtern results of surgical palliation and on different concepts concerning tcpc (total cavo-pulmonary connection). methods. between and , a total of patients (mean age . ae . years) underwent surgical fontan palliation at our institution by tcpc technigue. in % of all patients, a staged concept was carried out, patients had a central fenestration ( mm). all of our latest patients in the operation series were palliated -according to the new ''fontan concept'' -with an extracardiac conduit as second step. in , inhalative no (nitric oxyde) therapy was also introduced in the early postoperative phase. results. kaplan-meier overall survival after a mean followup of years was . % (in patients with staged procedure . %, . % in patients with fenestrated fontan). out of patients survived a periopertive fontan take-down. without any exception, we lost patients in the learning curve phase, of them because of neurologic complications, patients died due to low cardiac output (lco). in those patients who were palliated with an extracardiac fontan, mortality was %; furthermore under no-therapy, perioperative mortality also was %. after ae months of follow-up, % of all patients were in nyha i, % in nyha ii, % of all patients were in sinus rhythm. pleuropericardial effusions were found in % of all patients. conclusions. definitive palliation by means of tcpc in patients with congenital single ventricle physiology leads to more than acceptable clinical results. staged palliation, fenestration procedures, extracardiac fontan and inhalative no-therapy were introduced as ''modern'' surgical therapy concepts and resulted in a significant positive influence on perioperative and longterm clinical results. neue erkenntnisse in der mund-, kiefer-und gesichtschirurgie background. as we are living in an aging society, the number of active patients older than is increasing. the impact of age on trauma related injuries, e.g. femur neck fractures, and their outcome has been well documented in the literature. so far, data on a broad cohort suffering from oraland maxillofacial injuries (omfi) are missing. thus it was the aim of the present retrospective analysis to observe the effect of increasing age on trauma related omfi. methods. the records of patients with omfi were collected at the department of cranio-maxillofacial and oral surgery at the medical university of innsbruck in the period from = = to = = . according to the who definition of elderly people the collected values were divided into persons older than years of age and younger. were younger and were older than years. data were registered regarding: diagnosis, age and gender, cause, type and localization of the injury and concomitant injuries. subsequently the data of both groups were compared and statistically analysed. statistical analysis was performed in spss (version . ) using chi-square-test, fisher s exact test and mann-withney u test. this was followed by a logistic regression analysis in order to investigate trends and to demonstrate significant differences between the groups. a value of p< . was considered significant. results. with increasing age the risk for a domestic accident was raising. the accident mechanism in the elderly people was mainly a fall ( . %) or was not reproducible ( . %). there was a significant difference between both groups regarding concomitant injuries. . % of the older and . % of the younger patients suffered from additional neurological symptoms (p < . ). until the age of the risk for concomitant neurological injury is increasing, beyond there is no significant higher risk. the injuries in the older patients were mainly referred to the soft tissue and the mid face. conclusions. thanks to major progress in general health care the percentage of elderly and most notably active old people in our society has been constantly stepping up in the past three decades. the increased number of concomitant injuries in elderly people requires a detailed investigation of the injured patient. furthermore medication and possible cardiovascular disease of the older generation restricts the indication for surgical treatment of these patients. influence of different surface termination on surface energy and subsequently on connective tissue attachment in vivo background. connective tissue attachment is of major significance for the longevity of transdermal=-mucosal implants. a tight soft tissue sealing around the implant prevents from acute and chronic infections. major focus of former investigations has been the influence of different surface roughness on the connective tissue attachment to the implant surface. the aim of the current investigation was to demonstrate the influence of different surface terminations of nano-crystalline diamond (ncd) on surface energy and subsequently its influence on in vivo connective tissue healing. methods. ncd coated titanium membranes were terminated either by hydrogen or oxygen and were compared to pure titanium membranes. these samples were evaluated by contact angle measurement, scanning electron microscopy, atomic force microscopy and electrostatic force microscopy to evaluate the surface potentials. to assess the in vivo integration, the different substrates were randomly distributed and inserted into the sub-dermal layer of wistar rats. animals were sacrificed after , and weeks to investigate the adjacent connective tissue histologically. cell number, connective tissue=implant contact ratio and scar formation were evaluated. statistical analysis was performed using wilcoxon-rank test and kruskal-wallis h-test. p < . was considered significant. results. the ncd coating of the titanium membranes preserved its microstructure. contact angle measurement confirmed h-termination hydrophobic and o-termination hydrophilic. o-termination resulted in a strong polarity, whereas no electrostatic interactions were observed at the hydrophobic surface. the histological evaluation demonstrated a comparable cell number after week in all groups. after four weeks a significantly increased cell number at the o-terminated ncd with a less tight scar formation was observed. furthermore a markedly higher connective tissue=implant contact was observed after weeks at the hydrophobic surface. conclusions. o-termination of ncd renders the surface electrostatically active. the surface polarity promotes connective tissue healing in vivo. furthermore the surface energy is of higher importance compared to the structure of the surface. the o-termination of surfaces thus is a promising technique for a controlled influence of connective tissue adhesion in vivo. the risk of concomitant injuries and complications in cranio-maxillofacial trauma. das risiko von begleitverletzungen und komplikationen in der kiefer-gesichtschirurgie background. the registration of concomitant injuries on patients with cranio-maxillofacial trauma is an important criteria to optimize the healing process and to minimize the incidence of complications due to unlevied diagnostic findings. interdisciplinary, cranio-maxillofacial trauma management includes exact documentation. therefore a large collective of patients was examined against the background of their maxillo-facial trauma to diagnose the additional injuries. methods. between - at the department of oraland maxillofacial surgery among patients with craniomaxillofacial trauma, patients ( . %) with concomitant injuries were registered. data of patients were recorded including age and gender, cause and type of injury, location and frequency of their additional trauma. statistical analyses performed including descriptive analysis, chi square test, fisher's exact test and mann-whitney s u-test. logistic regression analysis determined the impact of different ages on the type of injury. results. within patients (mean age ¼ . ; #:$ ¼ . ) the most common sort of concomitant injury occured during sports, household and play ( . % each). the most frequent type of additional injury was the commotio cerebri in . % ( patients). fracture of the base of the skull occurred in patients ( . %), patients had a fracture of the skull and patients suffered from contusio cerebri. even one patient had a paresis of the facial nerve. in patients injuries of the eye were denoted, among them . % had a contusio bulbi and patients a retrobulbar hematoma. contusio of the lung appeared in . %, blunt abdominal trauma in . % and a fracture of the cervical spine in . % of patients with concomitant injuries. in patients fractures of the facial bone were recorded. soft tissue injuries of the face were found in patients ( . %). in concomitant injuries male persons aged between to are prone to cervical spine fractures (increase of %=year of age) and thoracal injuries (increase of %=year of age), as well as neurological trauma (increase of %=year of age) mainly found in traffic accidents. conclusions. in the catchment area of our department injuries of the neurocranium and the eye were often associated with trauma of the viscerocranium. interdisciplinary and coordinated management is not only important for the initiation of preventive measurements but also for forensic causes. to minimize the complication rate and to optimize the therapy a neurological-, neurosurgical-, as well as eye-consiliary examination should be preferably accomplished at a preoperative stage on the awakened patient. background. orbital injury may lead to incarceration of periorbital tissue and to ocular motility disturbances and diplopia on a long-term basis. however, orbital surgery is not free of risks. the treatment of periorbital lesions demands a precise planning approach in order to secure high success rates without causing iatrogenic damage. we want to demonstrate computer assisted surgery as part of the surgical routine of posttraumatic orbital reconstruction. methods. four cases of posttraumatic orbital deformities are presented. two patients showed protruding bone fragments after unrecognized fractures of the orbital walls. two patients presented with foreign bodies in the orbital cavity after shotgun injuries. in all four patients preoperative acquired ct-data was reformatted on a commercially available d-navigation system. image guided surgery in the orbital cavity was performed using an intraoperatively calibrated high-resolution endoscope. results. the shotgun pellets and the protruding bone fragments were easily detected and removed via a minimal invasive access. diplopia and bulb motility improved significantly. postoperative rehabilitation was restricted to a few days. conclusions. according to our opinion computerized navigation surgery of the orbit can improve the results of surgery in terms of safety and accuracy. these extended techniques should lead to a more direct and less invasive method for approaching orbital lesions or posttraumatic deformities giving the surgeon a high degree of security in sparing vital anatomic structures. background. surgically assisted rapid maxillary expansion (sarme) has become a widely used and acceptable technique to expand the maxilla in adolescents and adult patients. sarme takes the advantage of bone formation at the maxillary edges of the midline, while they are separated by an external force. sarme is indicated in patients with isolated, considerable (more than mm) transverse maxillary deficiency. while surgically assisted palatal expansion is performed in patients after closure of the sagittal palatal suture, conservative rapid maxillary expansion can be used in younger patients. studies concerning such cases show, that just % of the expanded width is located in the area of the palatal suture, while the rest of the extention ( %) are reached by dentoalveolar movements like tipping. the aim of this study was to evaluate the amount of expansion caused by expansion of the maxillary suture and by the dentoalveolar complex. furthermore changes of the nasal cavity should be discussed. methods. all patients included in the study showed a tranverse maxillary deficiency of at least mm. all patients were older than years ( min, max). in all patients a fractional le fort i osteotomie consisting of sagittal osteotomie and osteotomie of the anterior maxilla and the pterygoid bone was performed. ct scans were performed preoperatively and about weeks postoperatively (after the needed expansion). measuring points were defined to evaluate the skeletal and the dental changes after maxillary expansion. conclusions. the results of the current study will be presented. background. the main indication for microvascular reconstruction of the face is the best possible functional and aesthetic outcome. here every special kind of missing tissue is to be substituted. by using the chimera-flap technique a combination of different transplants for individual defect coverage is possible. methods. in seven patients with extended or penetrating defects of the lower face, reconstruction was performed with a double flap technique. a combination of microvascular iliac crest transplants or microvascular femur transplants for mandibula reconstruction and an anterolateral thigh perforator flap (altpf) or saphenus perforator flap for soft tissue reconstruction was performed after ablative tumour surgery. the pedicle of the altpf or saphenus flap was used for elongation of the microvascular bone flap pedicle. all patients had radiotherapy weeks after surgery. results. all patients had good functional and aesthetic results and have been successfully treated with implant retained prostheses. there were no severe postoperative complications. there was no tumour relapse within - months postoperatively. conclusions. the chimera-technique makes good aesthetic and functional outcome possible. the iliac crest transplant is of a good dimension for reconstruction of non-high atrophic mandibles after complete resection. the microvascular femur is well suited for covering partial defects of the mandible. implant placement is possible in both transplant types. the altpf and the saphenus perforator flap have a low incidence of complications and donor site morbidity and can be shaped adequately to a soft tissue defect of the lower face. parry-romberg-syndrom (hemiatrophia faciei progressiva) -interdisziplinäre zusammenarbeit mehrerer ü bergreifender fächer bei der definitiven diagnosestellung und den daraus resultierenden therapiemöglichkeiten zugt gesichts-und schädelskelett. die hemiatrophia faciei progressiva (v. romberg) ist primär durch einen schwund der betroffenen gesichtsseite, an der die haut, das subcutane fettgewebe und bindegewebe und später auch die muskelatur und die gesichtsschädelknochen beteiligt sind. die ausgeprägte gesichtsasymmetrie ist häufiger als ein funktionsausfall ursache der behandlung. nur eine effiziente diagnostik sichert eine gute therapie und gute resultate bei einem romberg-syndrom-patienten. bei der diagnostik wird nicht nur die mund-, kiefer-und gesichtschirurgie herangezogen, sondern interdisziplinär mit der dermatologie, hno, mund-, kiefer-und zahnheilkunde, augenheilkunde, neurologie, psychiatrie, plastischen chirurgie und radiologie zusammengearbeitet. es werden die jeweiligen disziplinen mit ihrem abklärungsgebiet beim romberg-syndrom präsentiert und dargestellt. in jeder disziplin werden die patienten in der dermatologie auf eine sklerodermie, in der neurologie -anhand eines mrtsdie neuralgiformen symptome und in der augenheilkunde die ophthalmologischen symptome, in der radiologie -anhand von bildgebungsverfahren (ct, szintigraphie) die knochenaktivität in bezug auf die fortschreitende knochenatrophie untersucht und abgeklärt. die therapieform wird nach der diagnosestellung und der daraus resultierenden diagnosebestätigung und anhand der symptomatik beim patienten bestimmt. verschiedene therapieoptionen wie eine autologe lipoinjektion, eine fettgewebstransplantation, eine freie mikrochirurgisch-anastomosierende fettgewebslappenplastik oder injektion allogener materialien werden angewendet. die diagnostik und das chirurgische vorgehen werden an zwei fallbeispielen demonstriert. die grundlegenden behandlungsstrategien stammen aus der zeit der beiden weltkriege. Ä nderungen der konzepte ergaben sich im bereich der sekundären rekonstruktion verlorengegangener strukturen sowohl im weichgewebe als auch im hartgewebsbereich durch etablierung neuer operationstechniken, welche die erzielung besserer ästhetischer und funktioneller ergebnisse ermöglichen. neben der beschreibung des traumamechanismuses erfolgt anhand von klinischen fällen die darstellung der versorgungsprinzipien. responsible for preventing fecal incontinence as well as enabling defecation. methods. works on anorectal vascularization are presented and diagnostic tools for clinical practice are discussed. results. filling and drainage of the internal hemorrhoidal plexus can be visualized by transperineal color doppler ultrasound. the terminal branches of the superior rectal artery exclusively contribute to the arterial blood supply of the internal hemorrhoidal plexus. according to anatomical studies an intramural network of anastomoses exists between the superior and inferior rectal arteries. ultrasound studies of the anorectum clearly highlighted a stage-dependent alteration of the morphology and perfusion of these terminal branches in different grades of hemorrhoids. conclusions. hypervascularization of the anorectum is proposed to contribute to the growth of hemorrhoids rather than being a consequence of hemorrhoids. pre-and postoperative assessment of the anorectal vascularization helps to judge the success of a technique for treatment of different grades of hemorrhoids. the doppler-guided haemorrhoidal artery ligation is a new, minimally invasive technique in the treatment of haemorrhoidal disease. since february patients with symptomatic second and third degree haemorrhoids have been treated this way at our department. postoperative complications occurred in , %. one month after treatment % of the patients were symptom-free and satisfied with the results. since there are very little data regarding the efficiency and the patient comfort on the long term, we questioned consecutive patients which had undergone surgery between february until december st . the questionnaire was done via telephone using standardised questions. patients with persisting or recurring symptoms were invited for a control re-examination. the results of this follow-up will be presented. background. guidelines may be helpful to standardize the management of hepatocellular and cholangiocellular carcinoma as the diagnostic and therapeutic spectrum has been considerably enlarged by recent developments. methods. ''state of the art'' guidelines deducted from the literature and from recent consensus conferences are elaborated; issues that remain controversial or not sufficiently documented by data are discussed. results. some standards have been introduced in hepatic surgery such as preoperative evaluation of liver function (and portal branch embolisation if required) or intraoperative ultrasonography. for other essential items such as techniques used for transsection of liver parenchyma or for hemostasis a variety of possibilities is at choice and the decision often depends on the personal attitude of the surgeon. as success of surgery is influenced by so many factors and imponderabilities, exact clinical evaluation is delicate and statements fulfilling the strict criteria of evidence based medicines are rarely found. only in a minority of patients with hepatocellular carcinoma transplantation or resection is possible. for the remaining patients, a variety of therapeutic procedures are warranted with effects difficult to compare given the bias of patient selection and the great inter-patient and inter-institutional variability. in the treatment of patients with bile duct carcinoma, surgery (liver resections for klatskin tumors stage bismuth i-iii, whipple's procedure for more distally localized tumors), if feasible, plays a key role as well. conclusions. excellent interdisciplinary cooperation is the clue to providing ''state of the art'' management of hepatocellular and cholangiocellular carcinoma. treatment not only has to consider tumor type and stage, but also the individuality and the overall condition of every single patient. background. colorectal carcinoma is one of the most common malignant diseases primarily diagnosed in the industrialized world. thanks to standardized surgical procedures and multimodal treatment concepts, the prognosis has improved considerably in recent decades. methods. state-of-the-art treatment of colorectal carcinoma is presented and discussed on the basis of the current literature, including the current status of minimally invasive techniques in the surgical treatment of malignant colorectal disease. results. carcinomas of the colon and rectum are two separate entities as far as biology, probability of local recurrences, metastasis patterns, surgical strategy and multimodal treatment regimes are concerned. operative treatment of colon carcinoma is generally standardized, but the concept of sentinal node biopsy is a new aspect. a metaanalysis of stage ii colon carcinoma showed a survival advantage of up to % for adjuvant therapies including -fu. the mortality rate for stage iii colon cancer could be reduced by - % with adjuvant chemotherapy. the operative standard for rectal carcinoma is heald's technique of total mesorectal excision. for proximal rectal carcinomas, a partial mesorectal excision with a greater distance (at least cm) to the edge of the tumor is adequate. with rectal carcinoma, neoadjuvant radiochemotherapy is more effective at reducing local recurrences and involves fewer complications than does postoperative treatment. accordingly, neoadjuvant radiochemotherapy is indicated at least for t- tumors of the lower and middle thirds of the rectum. in all, total survival and fewer local recurrences are seen with combined radiochemotherapy for rectal carcinoma. a number of randomized prospective studies published since showed comparable long-term results for laparoscopic and open colon surgery. the results of such studies on rectal carcinoma are not yet available. conclusions. the key factors for improving the prognosis of colon and rectal carcinoma are, besides early diagnosis, standardized surgery and multimodal, individualized treatment concepts. prophylactic operations in palliativ surgerya conflict? background. to date approximately % of the eu-citizens decease on malign tumors. here an increased tendency was noticed in the past. this circumstance is present in the surgical day-to-day life. patients with predictable and linited prognosis often require the decision whether a prophylactic surgical procedure would prevent further complications or may declerate progression of malign tumors. methods. the status and progression of patients with oncological focus were analyzed in the department of surgery of the helios-hospital schwerin. two groups were studied. first surgical procedures due to general symptoms of the tumorous disease. second, surgical therapy of specific symptoms as a consequence of the tumor. results. inter-disciplinary diagnosis and discussion were crucial for the decision whether a palliativ-prophylactic operation was necessary or not. futhermore, prophylaxis in palliative medicin and surgery required a multi-disciplinary therapy regime. for the inter-disciplinary decision, guidelines proposed by the established ''tumorboard organization'' were applied. for general symptomatic treatment, palliativ-prophylactic procedures due to pain therapy, gastro-intestinal symptoms, emesis, ileus, ascites, icterus, cachexia, respiratory and urological complications, and wound management were accomplished. conclusions. prophylactic operations are frequent and represent the reality in palliative surgery. the ''tumorboard organization'' was administrable for a structured ultimate therapy decision. here forensic guidelines regarding self-determination, protection of integrity, autonomy of the patient, and euthanasia have to be considered. the perception of the personally responsibility of the attending physician still possess highest priority. background. within the last decade thyroid surgery has been radicalized. two parties have emerged from the discussion. one group, trying to preserve thyroid as central element of the body -the other one, in light of an easy replacement therapy, does not feel the need for that. methods. we compare patients operated from - at our department. one group underwent dunhilloperation (dh) n , the second thyroidectomy (t) n . complication rate and change of therapy were compared, remaining tissue was sonographed. the patient's opinions were sought using questionnaires. results. monitoring period lasted - months. recurrensrate showed no significant difference (dh: . =t: . ) and bleeding results also didn't show any differences. we did notice a higher hypoparathyroidismus rate with the thyroidectomy group (dh: . =t: . ). % of all sonographies in the dunhill group required further investigation because of remaining nodulare tissue. changes with substitution therapy didn't show any differences. the patient's opinions were identical in both groups. conclusions. both techniques require a simple substitution therapy. they are both safe methods, although the hypoparathyroidism is higher with thyroidectomy. on the other had we observed a progress in learning over the years thus we noticed no significance in . when using dunhill procedure, remaining tissue must be checked regularly. in our opinion, it is no benefit for patients with replaced tissue. evaluation of a new needle for thyroid fine needle aspiration biopsy p. wretschitsch , m. glehr , t. kroneis , a. leithner , r. windhager background. to verify the destinction of thyroid tumors, the volume of harvested cells in fine needle aspiration biopsy is one of the significant parameters for histological criteria and diagnosis. in consequence of the new aeration valve, the new needle is deaerated after the aspiration. thereby no blood or other not thyroid-cell elements are aspirated and more thyroidcells are harvested. methods. under blinded setting punctures, for each needle (standard needle, -needle with air valve and multi needle system with air valve), from fresh pig thyroid gland were made and recorded. the measurement was done according the manufacturers recommendations for casy (casy + technology, reutlingen). the aspirated cell material was evacuated into ml casyton (cell-culture liquid, casy + technology, reutlingen) and calculated with the casy (casy + technology, reutlingen) cell counter. total cell amount and amount of vital cell was counted and recorded. statistical analysis was performed using t-test (p < . was considered significant). results. per needle respectively punctures were made and counted. the mean cellular amount of the standard needle was cells=ml. the mean cellular amount of the -needle system with aeration valve was cells=ml. the average of cell amount for the multi needle system (thyrosampler + kurtaran-frass, vienna) was cells=ml. the mean difference between the standard needle and the -needle system with air valve was significant with total cells (p ¼ . ) and with vital cells (p ¼ . ). the difference between -needle and multineedle system was not significant with total cells (p ¼ . ) and with vital cells (p ¼ . ). tag conclusions. the needle systems with the air-valve lead to a significant higher cell amount in needle aspiration biopsy. according to the requirement of cytological diagnosis more cell volume could be harvested, which is a well-defined benefit. does the lunar phase influence the incidence of postoperative haemorrhage after thyroid surgery? a preliminary report background. it is claimed by non-scientific sources that operations carried out at waxing moon or especially at full moon are associated with a higher incidence of postoperative complications. therefore patients referring to lay press confront surgeons with the lunar phase's influence and claim for special dates for surgery. postoperative haemorrhage is a typical complication after thyroid surgery with an incidence of about . %. thus it is a suitable to assess this assumption by evidence-based data. methods. we retrospectively evaluated patients requiring reoperation after thyroid surgery. the exact time of skin incision was evaluated by anaesthesia's reports and its lunar phase was calculated by an online-calculator. results. in a timeframe of days (in all) around full moon patients had to be reoperated, days around new moon patients needed surgical reintervention. patients were operated during waxing moon, the phase that is believed to be a risk for postoperative complications, and patients during waning moon. no differences were seen between the categories st þ th quarter ( operations), the quarters around new moon, and nd þ rd quarter ( operations), the quarters around full moon. conclusions. our study shows no correlation between postoperative haemorrhage after thyroid surgery and lunar phase at initial surgery. these evidence-based data prove, that lunar phase does not influence the risk of bleeding after surgical interventions. these results should serve as information for those patients, who are convinced, not to be operated during full moon phase. the result should also bring the ''superstition'' to a halt. background. recently gender-specific medicine has become the focus of interest. after thyroid surgery we observed more hypocalcaemia-related symptoms in women than in men. our goal was to find out gender-specific differences in the postoperative calcium-and parathyroid hormone (pth)-kinetics. methods. pth-and calcium-levels as well as postoperative hypocalcaemia-related symptoms were monitored according to a prospective protocol. a total of women and men underwent extensive thyroid surgery. postoperative calcium levels revealed a non-significant difference of . mmol between women and men on the st postoperative day. perioperative pth-kinetics showed no significant differences too, neither in symptomatic patients, nor in the whole study population. the rate of postoperative hypocalcaemia-related symptoms was about higher in women than in men ( - %, respectively). conclusions. despite of similar perioperative pth-and calcium-kinetics women suffer more often from postoperative hypocalcaemia-related symptoms. the mechanism remains unclear and needs further research in gender-specific postoperative calcium-metabolism. background. grave's disease (gd) is thought to be associated with a higher incidence of postoperative hypocalcaemiarelated symptoms. methods. parathyroid hormone (pth)-and calcium-levels as well as postoperative hypocalcaemia-related symptoms were monitored according to a prospective protocol. preliminary data were analysed for patients with an observation period of more than months. results. total or near-total thyroidectomy was carried out in patients with gd and patients with benign euthyroid multinodular goitre. differences between patients with gd and patients with benign euthyroid nodular goitre were found for postoperative hypocalcaemia-related symptoms ( . , . %, respectively). these findings were statistically significant (p < . ). furthermore, no significant differences were found in perioperative pth-and calcium-kinetics between the groups. patients with gd were of a significant (p < . ) lower mean age ( ae ) than patients with benign euthyroid multinodular goitre ( ae ). conclusions. there is a significant higher risk of postoperative hypocalcaemia-related symptoms after surgery for gd compared to benign euthyroid multinodular goitre. there is no significance concerning the risk of permanent hypoparathyroidism in our preliminary data set. background. intraoperative parathyroid hormone [pth] monitoring is an important prerequisite for minimally invasive parathyroid surgery. thus, surgical success essentially depends on the correct intraoperative interpretation of the pth-decay. pth-''spikes'' caused by unintentional ''manipulation'' of the hypersecreting glands during dissection may lead to interpretation problems. it is unclear how often these ''spikes'' occur and how they influence the operative strategy. we evaluated manipulated pth-excretion during surgery in a large number of patients and analyzed its influence on the interpretation of the intraoperative pth-curve. methods. intraoperative pth-values (intact pth, nichols, san jose, california) of patients with primary hyperparathyroidism and single gland disease were analyzed. of these patients, ( . %) were successfully treated with open minimally invasive parathyroidectomy (omip), ( . %) with primary bilateral neck exploration (bne) and ( %) patients had to be converted from omip to bne. to evaluate the occurrence of manipulation, patients were divided into groups: ''moderate'' pth-increase (< pg=ml), ''extensive'' increase (> pg=ml), ''no'' increase (ae pg=ml) and ''decrease'' before excision. changes were referred to the ''baseline''-level which was sampled right after induction of anaesthesia and before incision. intraoperatively, pth was measured before, , and min after removal of the enlarged gland. results. overall ( %) had a moderate increase and ( . %) an extensive increase. no increase occurred in ( . %) and a decrease in ( . %) patients. in patients undergoing omip, ( %) glands were manipulated moderately, another ( %) glands were extensively manipulated, ( . %) had no increase and ( . %) had a decline. in patients undergoing primary bne, ( . %) glands were manipulated moderately, ( . %) extensively and ( %) had no increase. a decrease was observed in ( . %) patients. a conversion from omip to bne was performed in patients because of incorrect preoperative localization by sestamibiscintigraphy and=or sonography. five ( %) of them had moderate manipulation and no patient had extensive manipulation. eighteen ( %) showed no pth alterations and ( %) a decrease, retrospectively. in none of the converted patients a misinterpretation of pth-''spikes'' were the underlying cause. conclusions. the data show that intraoperative manipulation is documented in bne and omip. the ''spikes'' caused by unintentional manipulation were identified by a subsequent prolonged pth-decline but did not lead to a change in the surgical strategy. parathyreoideakarzinome zählen zu den seltenen tumoren und sind für weniger als % aller primären hyperparathyreoi- background. at international meetings, delegates from many countries report an increasing lack of young doctors willing to choose operative specialities. the aim of this study was to evaluate the working conditions for surgeons in austria and to define the most crucial items calling for amelioration. methods. an anonymous survey was prepared and by e-mail all the members of the austrian surgical society were asked to complete a questionnaire which could be reached online by a direct link. it comprised twenty questions and was kept deliberately short in order to require a minimum of time for response. results. just some examples of the essential items can be given here: working conditions (such as working hours and payment) have to be improved. notably the young surgeons require career perspectives that are better and defined more clearly. the time spent for non-medical duties such as organization and documentation must be reduced. more priority is needed for surgical training both in the operating room and in practically oriented courses. conclusions. this evaluation provides the basis for further discussion at a session dedicated to this topic during the austrian surgical congress of . background. surgical training and education is neither standardized nor regulated. there is no validation, no obligatory training goal and no implementary rotation system. recently, the training permission for surgeons in education in the surgical department of kaiserin elisabeth spital has been shortened by the austrian medical association from to years without evidence based data i.e.without the consideration of the underlying number of operations performed in the clinic. methods. the surgical department is a center of thyroid and parathyroid surgery, which also covers the extended oncological cases, minimal invasive surgery, hernia operations and has the largest capacity for acute abdominal diseases in vienna. to analyze the quality of surgical education, the whole number of operations as well as the number of trainees in nd and th training year are tallied for analysis. results. in , a total number of operations ( thyroid and non thyroid operations) have been performed in our surgical department. trainee a ( years of education) performed ( thyroid and non thyroid operations), trainee b ( years of education) operations ( thyroid and non thyroid operations). the non thyroid operations of trainee a included cholecystectomies, herniotomies, appendectomies, operations of colon or small bowel, all other will be listened in detail. trainee a had = , trainee b = gastroscopies=colonoscopies performed. conclusions. the number of operations prove that the goal of training for surgeons in education is easily achievable. the reduction of training permission by the vienna medical chamber was not evidenced by data. however, this procedure has once again raised the insufficient structures in surgical education, the lack of valid training program and standardized approaches for a defined rotation and the obligation for both, senior surgeons and trainees to perform a certain number of teaching operations. a structured reform of rules and regulations for training is necessary. background. the purpose of this study was to review our hospital's experience in a retrospective single-center analysis of all patients undergoing surgery for posttraumatic thoracic pathologies between and . methods. from to october a total of aortic procedures were performed at our institution. eighty eight patients ( . %) underwent an intervention ( surgical procedures, stentgraft implantations) due to a posttraumatic injury of their thoracic aorta. in > % the descending aorta was involved, the injuries consisting of % aortic rupture, . % posttraumatic pseudo-aneurysms and . % aortic dissection. in the surgical cohort . % of the patients had to undergo an emergency procedure, . % an urgent and . % an elective procedure. there were . % female patients and . % male patients with a mean age of . years (range - yrs). results. during the three decades total hospital mortality was . % with a decrease over the years, thus resulting in a hospital mortality of . % ( - ) versus . % ( - ) . hospital mortality in the emergency group dropped from . % ( - ) to . % ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) . improved outcome is mainly due to preoperative aggressive control of blood pressure and aortic shear forces using -blockade, intraoperative the use of heparin bounded circuits with cardiopulmonary bypass and most of all, a selectively delayed operative procedure (!). conclusions. although endovascular stent graft techniques continue to evolve, emergent=urgent patients will be anatomically not suitable for stent grafts and long term outcomes have yet to be determined. we therefore still consider selectively delayed surgery in patients with posttraumatic aortic pathology as a cornerstone in the choice of treatment for these patients. combined surgical and endovascular repair of complex aortic pathologies with a new designed hybridprosthesis background. in the present study the use of a new combined surgical and endovascular approach in the treatment of aortic dissection or aneurysm is evaluated. the aim of this technique is to treat extensive aortic diseases in a single stage procedure. the operative and follow up data are summarized in this report. methods. between = and = six patients ( ae years; female) with different aortic pathologies ( dissections, aneurysms) underwent replacement of ascending aorta, aortic arch and stentgraft implantation into the descending aorta using the e-vita open endoluminal stentgraft under circulatory arrest in moderate hypothermia with selective antegrade cerebral perfusion. the stentgraft was deployed under direct vision through the open aortic arch into the true lumen. results. intraoperative antegrade stenting of the descending aorta combined with distal ascending aorta and aortic arch repair was performed successfully in all patients. all patients survived the procedure one patient had neurological deficit, which recovered completely. a complete thrombosed perigraft space was observed in patients after one to eleven days. in two patients a partial thrombosis of the false lumen of descending aorta was observed. one patient underwent thoracoabdominal repair five months later. conclusions. this report shows that a combined surgical and endovascular approach of extended aortic lesions is a feasible option and extends aortic repair in a single stage method without increase of risk. background. to evaluate mid-term results of supraaortic transpositions for extended endovascular repair of aortic arch pathologies. methods. from through , patients (mean age yrs) with aortic arch diseases were treated (arch aneurysms n ¼ , type b dissections n ¼ , perforating ulcers n ¼ ). strategy for distal arch disease was autologous sequential transposition of the left carotid artery and of the left subclavian artery in patients. strategy for entire arch disease was total supraaortic rerouting using a reversed bifurcated prosthesis in patients. endovascular stent-graft placement was performed metachronously thereafter. results. two in-hospital deaths occured (myocardial infarction on the day prior to discharge n ¼ , rupture while waiting for stent-graft placement n ¼ ). at completion angiography, all reconstructions were fully patent. four patients had small type ia endoleaks, two of them resolving spontaneously. mean follow-up is months ( - months) . three late deaths occured (myocardial infarction n ¼ , sudden unknown death n ¼ ). one year survival was % and three year survival was %, respectively. redo stent-graft placement was performed in one patient after months (type iii endoleak). the remaining patients had normal ct scans with regular perfusion of the supraaortic branches without any signs of endoleaks. conclusions. mid-term results of alternative treatment approaches in elderly patients with aortic arch pathologies are satisfying. extended applications provide safe and effective treatment in patients at high risk for conventional repair. background. to determine mid-term durability of endovascular stent-graft placement in patients with perforating atherosclerotic ulcers (pau) involving the thoracic aorta and to identify risk factors for death as well as early and late adverse events. methods. from through , patients (mean age yrs) presented with pau, seven patients had rupture. seventy-eight percent were unsuitable for conventional repair. mean numeric euroscore was and mean logistic euroscore was . median follow-up was ( - ) months, being complete in all patients. outcome variables included death and occurrence of early and late adverse events. results. in-hospital mortality was %. primary success rate was %. actuarial survival rates at , and years were , and % and actuarial event-free survival rates were , and %, respectively. hemodynamic instability as well as logistic euroscore was identified as independent predictos of early and late adverse events. conclusions. endovascular stent-graft placement in patients with pau is an effective palliation for a life-threatening sign of a severe systemic process. hemodynamic instability at referral and a high preoperative risk score predict adverse outcome. during mid-term follow-up, patients are mainly limited by sequelae of their underlying disease. background. the performance of endovascular stent-graft placement in patients suffering from aneurysms involving the descending aorta originating from chronic type b dissections is unclear. methods. within a two-year period, we treated six patients with this pathology. four patients required extension of the proximal landing zone (autologous double transposition n ¼ , subclavian-to-carotid artery transposition n ¼ ) prior to stentgraft placement. results. supraaortic rerouting procedures and endovascular stent-graft placement were performed successfully in all patients. closure of the primary entry tear, full expansion of the stent-graft and consecutively, thrombosis of the false lumen was achieved in five patients. in one patient with a short proximal landing zone, a persisting type ia endoleak had to be observed. in all patients with successful primary entry closure, a reduction in aneurysm diameter could be seen. mean follow-up is months ( - months). conclusions. endovascular stent-graft placement of aneurysms involving the descending aorta originating from chronic type b dissections may serve as a valuable treatment option in a complex pathology. the chronic dissection membrane can be successfully approximated to large parts of the native aortic wall. a sufficient proximal landing zone is mandatory for early and late success. background. the aim of the study was to determine late vascular events in patients after endovascular stent-graft placement of thoracic aortic diseases. methods. between and a total of patients (mean age a; % male ¼ ) underwent endovascular stentgraft placement of thoracic aortic diseases at our institution. indications were aneurysms (n ¼ ), acute and chronic type b dissections (n ¼ ), penetrating ulcers (n ¼ ) and traumatic transsections (n ¼ ). results. during a median follow-up of months ( - months), in % of patients, late vascular events were observed. the highest incidence was observed in patients after stent-graft placement for type b dissections ( %), closely followed by patients after stent-graft placement for penetrating ulcers ( %). the incidence after stent-graft placement for aneurysms was %. no events were observed in patients after traumatic transsections. interestingly, patients undergoing stent-graft placement due to dilatative arteriopathy developed further dilatations in other regions and patients undergoing stent-graft placement due to obliterative arteriopathy were more prone to sustain obliterative diseases in other vascular beds. conclusion. this study clearly outlines the necessity of a close follow-up in these patients, not only to assess long-term outcome of endovascular stent-graft placement, but also to monitor these patients for new vascular pathologies. tenascin-c as a key factor in the remodeling of the ascending aorta leading to chronic dilatation and acute type a dissection background. the extracellular matrix molecule tenascin-c (tn-c) plays an important role in embryonic development, wound-healing, cancer invasive fronts and myocardial remodeling by loosening the linkage between connective tissue and cells lying within. as there is clear evidence for an involvement in vascular remodeling as well, we hypothesized tn-c being a mediator in the pathogenesis of chronic dilatation of the ascending aorta and acute aortic dissection. methods. ascending aortic wall specimens were obtained from patients undergoing aortic reconstruction due to chronic dilatation of the ascending aorta (n ¼ ) and acute aortic dissection stanford type a (n ¼ ). specimens of patients (n ¼ ) undergoing aortic valve replacement with a macroscopically normal aorta served as controls. formalin-fixed paraffin-embedded specimens were morphologically evaluated by hematoxylin-eosin staining and immunostaining for tn-c expression. results. there were no differences in clinical characteristics concerning age and gender between patients with acute dissection, chronic dilatation and control. patients with a known connective tissue disorder or bicuspid aortic valve were excluded from the study. histologic examination showed a clear difference between chronic dilatation and acute dissection. in chronic dilatation tn-c staining was homogenously distributed throughout the media parallel to the orientation of vascular smooth muscle cells. in contrast specimens in acute aortic dissection showed a focal strong positive staining especially surrounding vasa vasorum and sites of intramedial hemorrhage and subsequent dissection throughout the whole vessel wall with tn-c negative areas in between. whereas in control aorta tn-c expression was almost absent. conclusions. these data suggest a role for tn-c in the remodeling of the ascending aorta leading to chronic dilatation and type a dissection. keeping in mind the differences in tn-c expression between chronic dilatation and acute dissection one may speculate that changes of the vascular wall leading to aortic dissection are mediated or at least accompanied by a change in tn-c distribution. a complicated type b-dissection: how (not) to do it j. demmer , m. alavian , p. pichler , c. groß chirurgie , akh linz, linz, austria; radiologie, akh linz, linz, austria complex type b-dissection is still accompanied with high mortality. we report on a years old male with a weeks ongoing history of thoracic pain. he was admitted to another hospital where a left renal artery stenosis in ct scan was suspected and a stent was applied into the false lumen of this artery. then the patient was transferred to our institution. angiogram revealed a type b-dissection with a hugh entry distal to the left subclavian artery, the coeliac trunk arising from the false lumen but the hepatic arteries adequately collateralized by the superior mesenteric artery. though guidewire insertion to the true lumen of the common hepatic artery was feasible, stent application was not possible.the entry in the proximal descending aorta was covered with an endostent, thoracic pain disappeared immediately. though a slight pain in the right upper abdomen and a moderate raise of got, gpt and y-gt was to be seen for a few days, the patient could be discharged weeks after stenting in good condition without having pain or signs of cholecystitis. another days later he was readmitted in bad condition with signs of peritonitis in the right upper abdomen, , wbc and a massive increase of liverenzymes. laparatomy was performed immediately. the gallbladder presented necrotic, the whole liver dark blue without any pulsation in the hepatic arteries. after choecystectomy an autologous venous bypass from the common iliac to the propriet hepatic artery was performed. the postop. course presented uneventful, angio-ct at postop. day showed a well contrasted bypass. the patient could be discharged at postop. day without any signs of infection and only slightly elevated liverenzymes. background. endovascular aneurysm repair (evar) evolved as a treatment option for high risk patients, in whom previously open graft replacement (ogr) could only be carried out with a high, nearly prohibitive risk or open repair even had to be denied. by employing evar the mortality rates (mr) were lowered to - % in specialized centers. unsolved is the problem of how to deal with patients unsuitable for evar. the hypothesis of this study was to test whether thoughtful watching combined with management of present risk factors or ogr were second best to evar in asa class iv patients with abdominal aortic aneurysms (aaa). methods. out of a total of aaa-patients two groups of asa class iv patients were selected and compared. group consisted of patients who underwent ogr from - . group included patients unfit or unwilling to undergo evar in the period from - . kaplan-meier survival estimates were calculated and possible differences were analyzed by the log-rank-test. results. the day survival was . % in group versus % after days following the denial of operation in group (p < . ). the days survival was again significant with p < . , group % versus group . %. after one year survival was not significant anymore, i.e. group . % versus group . % (p < . ). conclusions. ogr has a significantly worse survival than conservative treatment in asa class iv patients in the first months after operation. after one year both treatment options show similar results. background. abdominal aortic aneurysm (aaa) size has been recognized as risk factor of rupture. several reports presented evidence that aaa with diameters exceeding . cm are associated with increased risk of rupture compared to smaller aneurysms. regarding these findings a diameter of more than . cm is generally considered as indication for exclusion. this analysis was undertaken to determine the influence of aneurysm diameter on long term outcome after either type of elective aaa repair. methods. eight hundred and sixty four consecutive patients underwent elective repair of an infrarenal aaa either by open graft replacement (ogr, n ¼ ) or endovascular aneurysm repair (evar, n ¼ ) from january, , through june, . median aaa diameter was chosen as threshold to discriminate between small and large aneurysms. patient characteristics, distribution of preoperative risk factors and postoperative outcome after either type of aaa exclusion were assessed. survival was compared using kaplan-meier estimates at years. results. overall median aaa diameter was . cm as well as in both treatment groups. analysis of risk factors only re-vealed that patients with larger aneurysms were significantly older (ogr . years vs. . years, p < . ; evar . vs. . years, p < . ) but comparison of individual health status expressed by the american society of anesthesiologists (asa) score did not reach statistical significance. at years, overall survival was higher in patients with small aneurysms ( . vs. . %, p < . ). similar results were obtained in patients undergoing ogr ( . vs. . %, p < . ) as well as evar ( . vs. . %, p < . ). conclusions. patients with aneurysms smaller than . cm have improved survival at years after either type of elective aaa repair. large aneurysm diameter is accompanied with increased age, which might negatively influence long term outcome. thus, the provoking issue to exclude small aaa before they reach . cm may rise again. background. about microsurgical techniques without sutures many references in literature databases are found. among facilities like rings, clips, stents, laser and adhesives the vessel coupling system (coupler + ) is mentioned. thereby two coupling rings interlock, which anastomose the vessels. methods. over the last two years in our division the coupler + was used in nine cases of free tissue transfer for breast reconstruction. in six of them the arterial and venous anastomosis were performed with the coupler + , in three cases only the venous anastomosis was done mechanically. in all cases the anastomosis was end-to-end. results. because of insufficient arterial adaptation in two cases we switched to a conventional procedure with sutures. all the other anastomosis showed a normal flow. except of one partial necrosis of a flap, which was not due to the coupler + , all flaps survived. the mean duration of doing the anastomosis was less than five minutes. conclusions. the coupling system (coupler + ) is a useful, secure and time saving tool for the venous anastomosis when performing a free tissue transfer. for the arterial anastomosis the conventional method is preferable, especially in cases of arteries with thick walls. background. non-operative management of splenic injuries is beneficial compared to surgery in hemodynamically stable patients. aim of this study was to assess whether conservative treatment would also translate into better quality of life post injury. methods. all consecutive patients with splenic injuries between january to february were included. splenic injuries were graded according to aast recommendations [ ] . patients were identified from our electronic inpatient index and stratified by non-operative treatment (non-operative group, nog) or primary surgery (splenectomy) (surgical group, sg). postdischarge quality of life was evaluated by a standardized telephone questionnaire. data are reported as total numbers (%) and statistical analysis performed using chi -tests. significance was assumed if p < . . results. of a total of patients enrolled, ( . %, nog) were treated non-operatively, and ( . %, sg) underwent splenectomy. splenic injury grading was comparable between both groups. after trauma, most patients were able to leave their bed three days after trauma ( rd postoperative (po) day: nog ( . %) vs. sg ( . %), p ¼ . ; st week po: nog ( . %) vs. sg ( . %), p ¼ . ; nd week po: nog ( . %) vs. sg ( . %), p ¼ . ), and the majority felt seriously ill during hospitalization (critically ill: nog ( . %) vs. sg ( . %), p ¼ . ; seriously ill: nog ( . %) vs. sg ( . %), p ¼ . ; not very ill: nog ( . %) vs. sg ( . %), p ¼ . ). unlike sg patients, about half of the nog patients could be discharged one week after trauma ( week: nog ( . %) vs. sg ( . %); p ¼ . ). sg patients significantly longer felt severe pain compared to nog patients ( weeks: nog ( . %) vs. sg ( . %), p ¼ . ; > months: nog ( . %) vs. sg ( . %), p ¼ . ). after discharge, nog patients were able to resume daily life activities earlier compared to patients after surgery ( weeks: nog ( . %) vs. sg ( . %), p ¼ . ; < month: nog ( . %) vs. sg ( . %), p ¼ . ; ! months: nog ( . %) vs. sg ( . %), p ¼ . ). conclusions. patients with non-operative management reported less pain and were earlier able to resume daily life after splenic trauma compared to patients undergoing splenectomy. plantation in order to prevent cmv disease. we recently evidenced immunomodulatory properties of pooled human immunoglobulines. the aim of this study was to evaluate influence of cytotect + and cytoglobin + a) on proliferative properties of peripheral blood mononuclear cells (pbmcs), b) on cell viability and c) on natural occurring cell mediated cytotoxicity. methods. pbmcs from healthy donors (n ¼ ) were stimulated with anti-cd ( mg=ml) or in an allogeneic mixed lymphocyte reaction (mlr). proliferation was determined by incorporation of [h]-labeled thymidine. apoptosis was measured by flow cytometric analysis (annexinv, -aad, cd , cd , cd , cd ). transmission electron microscopy (tem) was utilized to support facs data. antibody dependent cell mediated cytotoxicity (adcc) was determined utilizing a standard europium release assay. cmvig (cytotect + biotest, cytoglobin + bayer) was used at therapeutic concentrations in all experiments. results. cytotect + and cytoglobin + evidenced anti-proliferative properties in t-cell specific stimulation and in mlr blastogenesis assays. this effect was dose dependent and ceased at concentrations of . mg=ml (p < . ). facs analysis and tem pictures revealed that the reduced proliferation was associated with induction of apoptosis in stimulated as well as in resting pbmcs (p < . ). furthermore, adcc against panc- and jurkat cell lines was significantly reduced after preincubation of effector cells with cmvig (p < . ). conclusions. our results provide evidence that cmvig containing drugs possess, in addition to their known application as passive cmv immunization, immunological features related to tolerance induction. background. multichannel intraluminal impedance (mii) monitoring is a new diagnostic tool for esophageal bolus transport and reflux assessment. methods. review on mii technology for diagnosis of esophageal disorders. results. impedance is a measure of resistance to the flow of an alternating electrical current. a low voltage current is applied to surface ring electrodes on a nonconductive catheter. impedance is determined by the conductivity of the medium bridging these electrodes. entry of liquid into the esophageal lumen produces a drop of impedance. gas entry results in a sudden rise of impedance. monitoring impedance in several channels detects direction, velocity and extent of the movement of liquid or gas through the esophagus. stationary equipment combining manometry and impedance is used for simultaneous esophageal motility and transit studies. transport studies using impedance only can also be done with probes intended for reflux testing. saline and a viscous gel are used to assess transport through the esophagus. in a recent study with combined impedance and manometry a significantly higher proportion of patients with incomplete transport of both liquid and viscous boluses ( = , %) presented with dysphagia than patients with complete transport of both ( = , %) or incomplete transport of only one ( = , %) of the test substances. equipment joining impedance with high-resolution manometry is currently being developed. a higher sensitivity and specificity for regional motility and transport abnormalities is to be expected from this technical advancement. portable recorders are available for -hour mii-and ph-monitoring. refluxes are detected by retrograde impedance changes: liquid refluxes are characterised by retrograde drops, gas refluxes by rapid increases and mixed liquid=gas refluxes by a sequence of both deviations from the baseline. the main advantage of impedance technology over conventional ph-monitoring is the detection of refluxes independent of ph. off antisecretory medication refluxes with ph > are mainly encountered postprandially, at a time when regurgitation is commonly experienced by reflux patients. the diagnostic yield of symptom to reflux association analysis is significantly increased by the inclusion of refluxes with ph > . distribution of impedance channels along the catheter facilitates the calculation of reflux exposure at different levels above the lower esophageal sphincter. conclusions. mii is a valuable new diagnostic tool for esophageal transport assessment without radiation exposure. combined mii-and ph-monitoring significantly increases the diagnostic yield of reflux testing. both applications of impedance technology have implications on surgical decisionmaking. trans-illuminated powered phlebectomy w. mayerhoffer the trans-illuminated powered phlebectomy was introduced in austria in about by smith and nephew as the ''trivex system''. a . mm shaver, as used by orthopaedists for cartilage, was used in order to mill out subcutaneous veins in a transilluminated technique. due to only a few and small incisions needed, the method seemed very attractive, so many surgical departments started using this orthopaedic equipment. most surgeons had a lot of complications, such as disastrous extensive haematomas, which made them stop using this method. mean while the trans-illuminated powered phlebectomy has been further developed. instead of the orthopaedic tools, a special phlebologic equipment is used now which allows the vein to be ''sucked'' out in a very non-traumatic order, instead of being milled out. the procedure is standardized and can be reproduced easily. it shows to be a non-traumatic and minimal invasive method to extract subcutaneous varicose veins, leaving a minimum of scares. large clusters of varicose veins are the best indication to use this procedure. the veins are made visible by transillumination in order to be accurately removed through a minimal number of small incisions. the new equipment and the technique will be described and explained. examples and results will be shown. background. total endoprosthesis in wrist joint is a rather new procedure compared to hip and knee surgery. biomechanics of the wrist joint is very complex and therefore designing the carpal and radial component of the prosthesis should respectfully consider this. indication for joint replacement and total endoprosthesis are posttraumtic and degenerative arthrosis of wrist joints. generally we tend to perform a partial fusion depending on where the arthrosis is located, but we have stopped to perform total arthrodesis of the wrist joint due to unsatisfying long term results, according to literature. we perform total endoprosthesis in all cases when a partial fusion is impossible for any reason or a total arthrodesis would be indicated. methods. nine males [ - a] four females [ - a]. seven of nine men suffered from a posttraumatic arthrosis ( slac snac). all patients sufferd from serious reduction of range of motion and severe pain. in one case a partial fusion was converted into a total prosthesis. two women had degenerative alterations of their wrists based on rheumatoid desease. the follow up covered months to years. results. in = cases range of motion was improved impressively and pain was relieved almost completely. seven men displayed a rom of s = = ; pro-supination totally unaffected and free. in one case we found rds. x-ray examination revealed a slightly false implant position of the radial component to us. rom in women was at least s = = . conclusions. in the beginning of wrist joint endoprosthesis results were less well and it was shown that this was due to misunderstanding biomechanical basics of the wrist joint. the fixation of the carpal element was a severe problem, like passing through the cmc , and joint line distally into the basis of the metacarpal bones and since cmc and joints have a rather high rom the distal element consequently often loosened immediately. recent implants respectfully avoid passing through these joints and loosening of the distal element has never been seen in all our cases. in our opinion the endoprosthesis of wrist joint is a real alternative to common procedures in the treatment of wrist arthrosis. background. volar fixed-angle plate osteosynthesis of distal radius fractures is a new method of treatment that provides the benefits of stable internal fixation without incurring the disadvantages of the dorsal approach. the aptus + plate is a new fixation implant that was introduced specifically for the purpose of managing dorsal displaced fractures (colles fracture) from the volar aspect. the aptus + system provides stepless multidirectional placement of screws. the range of swivel ae in all directions, can be freely selected by the surgeon. methods. between april and september ( months) we have seen patients with a distal radius fracture. eighty five patients ( women, men; mean age . years) were treated with the medartis + aptus + plate. our therapy regimen: closed reposition in the operating room palmar access along the radial side of the flexor carpi radialis (fcr) muscle plating with subchondral screw placement begin of physiotherapy on the first postoperative day and removeable orfit splint for weeks. results. the clinical and radiological follow up after Ø months showed no secondary loss (relative protrusion of the ulna, dorsal or radial tilting) of correction. compared to the contralateral side the range of motion was decreased for % in extension=flexion, % in ulnar=radialduction, % in pronation=supination. the grip strength was decreased for % compared with the contralateral side. the castaing score shows perfect results, good results, adequate result and no moderate, poor or bad results. conclusions. our data clearly show that secondary correction loss can be avoided with the aptus + system. the system provides a reliable subchondral screw placement and solid support for the joint surface. this new plate makes meaningful early mobilization possible. the palmar approach provides exact fracture reposition and with its good soft-tissue coverage not only reduces the risk of infections but also offers the possibility of not having to remove the plate. a cancellous bone graft is not necessary. background. the arthrosis of the first carpometacarpal joint is one of the most common problems in handsurgery. primarily elderly women are affected by rhizarthrosis. under conservative treatment the continuing progress leads to operation indication, for pronounced pain and insufficiency of conservative therapy options. the huge amount of well-know operation methods shows, that no satisfying option could have been described. next to simple resection procedures, today interposition and suspensionarthroplasties play a key role in the care of arthrosis of the thumb saddle joint. the amount of endoprothetic procedures in the first carpometacarpal joint has been rather small, the results often remained unsatisfying. a rather new concept is the prosthesis elektra, developed by fixano in , that reminds of the classic de la caffiniere prosthesis, first described in . methods. in the years = in our department patients (Ø . years - , male:female ¼ : ) with advanced saddle joint arthrosis were treated with different operation methods: patients received an elektra-prosthesis, patients a resection-suspension arthroplasty martini. thirty seven of these were recorded in the follow-up study. the rest of the patients were deceased, removed or not accomplishable. the follow up examination contained following criteria: dash score, subjective pain scale, range of motion and radiology. results. in the follow-up examination of patients no significant differences in average results of the different operation methods could be investigated. thus, the group of patients with very good results contained significantly more patients with elektra prostheses than patients treated with martini operation. in the opposition a higher complication rate could be seen in patients with elektra prostheses. especially the loosening of the implant cup was a frequent complication in average dash score, subjective pain scale and range of motion showed similar results in both methods. conclusions. our results show that the elektra prosthesis is a good and efficient alternative method to other well-known treatment concepts of rhizarthrosis. the amount satisfying results of the elektra group excel the good results in the martini group. the biggest problem concerning the elektra prosthesis is the high frequency of cup loosening, that is unacceptable high. the treasons for that matter could be complex: . biomechanical problem, because of the converting of a saddle joint to a universal joint, . metallurgic problem that could be solved by the use of different surface material, . vitality problem of the os trapezium because of an unfavourable quotient of metal and bone. unsettled remains, if revision or cementing of the cup could be a possibility to salvage of the implant. a conversion of the procedure to resection methods is possible anytime. so the use of the elektra prosthesis still is a good alternative under the condition of a clear indication and information of the patient about the possibilities of loosing. background. posttraumatic arthrosis as well as loss of function in the pip joint due to rheumatoid disease mean for the patient to be afflicted with pain. in many cases this leads to serious diminution of quality of life and in some cases the patient looses his occupation. it is the goal of implantation of total endoprosthesis to sustain movement and improve the range of motion, but most importantly to exterminate the pain. certainly removement of pain can be obtained by a simple arthrodesis but this of course is less satisfying in comparsion with mobility in the pip joint provided by the prosthesis. since pip joint endoprosthesis is a relativley young and new procedure there are only view experiences found in literature. methods. nine pip-endoprostheses have been implanted without cement so far. in cases posttraumtic arthrosis was the indication for this procedure; in cases rheumatoid destruction of the joint. in all cases the collateral ligmantes were intact. four lpm and sr avantas were used. postoperative the finger was placed on a splint for one week in intrinsic plus position. after days we commenced passive ergotherapiy and after one week we started with active motion. results. mobility was improved impressively in cases. all patients were almost completely free of pain. all pipjoints were stable. there was one patient who suffered from a new trauma after the operation and the proximal component had gotten loose, so we had to convert it to an arthrodeses. in cases we found a significant loss of extensor tendon function. conclusions. development and design of pip endoprosthesis has not found its final goal; this can be told by the variety of pip-joints which are found in the free market. passing throgh the extensor tendon is a sensitive point in the procedure and it should be noted in the preoperative information that there might be a decreased extensor tendon function. nevertheless in our eyes the pip prosthesis represents an intersting alternative to pip-arthrodesis and in cases of failure of the prosthesis it can be easily converted into a classical arthrodesis. osteosynthesis of proximal humeral fractures using a dynamic angular stable plate e. aschauer , l. schmid , c. maier unfallchirurgie, bad ischl, austria; fa. hofer, fürstenfeld, austria background. fractures of the proximal humerus are frequent and represent a therapeutic problem. the proximal humerus plate of the dfd system (double-fix-dynamic) fixes the fragments angular and rotational stable and is implanted minimally invasive. a special instrument allows precise closed reduction. due to the dynamic character of the osteosynthesis bone healing is stimulated. methods. two plates are connected with short screws in linear holes so that they can move against each other. the head fragment is fixed to the main plate with long screws coming steeply from distally. the dynamizing plate fixes this situation to the humeral shaft. for implanting the plate is fixed to a guide instrument, which therefore can be used as a joy-stick. so it is possible to reduct the shaft to the head exactly. to implant the dfd only two small incisions are required. one of cm to slip the plate under the delta muscle and to insert the head screws. and a second of cm proximally to fix the guide instrument and insert the shaft screws. in bad ischl the dfd-php is in use since november . up to now patients were operated. fourty three were female, male. the average age was . years ( - ). in cases it was a dislocated subcapital fracture. nineteen had a threepart-, a fourpart fracture. four fracture dislocations and true headsplits also could be done with closed reduction on this technique. four fractures were located at the anatomical neck. results. our first experiences were very well. currently we cannot report any complications due to the implant. there was no loosening or breakage. we watched no loss of reduction. noticeable was lack of pain immediately after the operation. so the patients came back to their former level of activity very fast. our complications were one infection forcing us to remove the implant -the case came to an end in pseudarthrosis which the patient bears well. another lady suffered a repeated fracture caused by a slight injury. one pseudarthrosis happened due to too early removal. conclusions. with the dfd-php now an implant is available that enables us to expand the indications for head preserving therapy of proximal humeral fractures. especially older people benefit from this method because there is hardly soft tissue damage but nevertheless a reliable stable situation that leads to bone healing in correct position and a good shoulder function. background. treatment of unstable distal metaphyseal tibial fractures with intramedullary nailing remains challenging even in fractures without intra-articular involvement. proximity to the ankle and biomechanical aspects makes the surgical treatment more complicated compared to fractures of the midshaft. intramedullary nailing (imn) is the ''golden standard'' for midshaft fractures but can be challenging in distal metaphyseal fractures. therefore, optimal surgical treatment of these fractures remains controversial. the aim of our study was to evaluate different tibial nails of the newest generation in a biomechanical approach. methods. defined osteotomy was performed in sawbone composite tibial fractures to create an unstable distal tibial fracture model. after nail insertion, distal tibial locking was performed with or locking screws. samples were cyclically loaded with , cycles and increasing load from ae n to and n. defined parameters such as alignment, varus, valgus deformation, antecurvation and recurvation were recorded. samples were then statically loaded until failure. acoustic emission technique was used to detect microfractures of bone, screws and nail. data according to failure of screws and nail were obtained. results. in case of physiological loading ( , cycles; ae n) loss of stability and damage of screws, nails and bone could not observed. failures occurred in loading series. stiffness was significantly higher in tibial nails with distal locking screws. stability of nail-bone construction was significantly higher in nails with distal locking options and in nails with diameter of distal locking screws more than mm. conclusions. intramedullary nailing can be recommened in unstable distal metaphyseal tibial fractures without intra articular involvement. four distal locking screws with . mm diameter should be used. our data suggests that immediate full weight bearing is possible postoperatively in young healthy patients without osteopenia even in this fracture type. because of the rising number of implantation rates of hip and knee arthroplasty as well as the increase number of osteosyntheses of the femur in geriatric patients the periprosthetic fractures are becoming more importance in orthopedic and trauma surgery. osteoporosis and the high rate of comorbidity makes a strong preoperative planning of the operation procedure necessary. prosthesis loosening or defects of the periprostetic bone may indicate a revision arthroplasty. in the new literature ostheosynthesis is usually conducted with locked screw plates as well as with intramedullary locking nail systems. a traditional alternative is the application of a condylar plate. usually used in trochanteric and subtrochanteric fractures of the proximal femur as well as in complex distal femur fractures it is also an effective implant system in periprosthetic fractures. several examples are shown and discussed. we respect to the classification of periprostetic fractures of johanson in our report about patients. six of them underwent a revision arthroplasty and in cases an osteosynthesis was done. five of them include the implantation of a condylar plate. the improved trauma room management by installation of a four-phase watch g. fronhöfer, m. kerl background. since the parameters of the severe traumatised patients of the trauma hospital graz have been collected and analysed at the trauma register of the dgu. according to the recommendation of the dgu a special four-phase watch was installed in to improve the effectiveness of the diagnosis and treatment process optimize in the trauma room. methods. the watchface has the typical colour coded phases and a flipchart shows the prepared standard sequence of trauma room management which has been developed interdisciplinary by surgeons, anesthetists, radiologists and carers. the parameters and the time process are further documented according to the guidelines of the trauma register of the dgu. results. the timelapse to x-ray or ct is reduced, the diagnoses are found quicker and patients can therefore be treated earlier at their adequate therapy. the motivation of the medical team is increased. conclusions. the four-phase trauma room watch has a many advantages and as recommended by the dgu should be installed in each trauma room. background. the treatment of an acute abdomen is without a doubt a domain of the surgical department. there are already specific treatment algorithms in place. due to the ever-present pressure to keep costs to a minimum, as well as the ever-changing technical advancements of diagnostics, it is vital to re-think and possibly modify existing treatment algorithms. therefore, patients in our facility were analyzed. methods. in erlangen, patients with an acute abdomen were treated in the timeframe from january , to december , . the average age was years, and the ratio males:females was : . . all data were collected prospectively through patient histories as well as clinical documentation. consequently, they were retrospectively evaluated. following the case history, labarotory tests and physical examination, sonography of the abdomen was used as the baseline diagnostic modality, as well as conventional radiography of the abdomen. results. of the treated patients, only ( %) required surgery. the average length of stay was days. in patients, a clinical diagnosis of appendicitis was made. in % of these patients, the confirmation of their diagnosis could be made, using the baseline diagnostic modalities. for the rest of the patients, further diagnostic modalities were needed (such as ct). in patients, a primary diagnosis of coprostasis was made. in % of these patients, a conservative treatment could be offered, and the patients left our facility without symptoms. in % of the patients, further diagnostic modalities (radiological and=or endoscopic) showed a finding that required surgical attention. conclusions. in the normal=routine clinical picture of appendicitis, baseline diagnostics are sufficient. however, behind apparently harmless diagnoses such as coprostasis, there are serious illnesses that may be masked. therefore a different course of action must be considered (ct). as a possible side-effect of this course, patients without pathological manifestations could be treated on an out-patient basis, thus reducing total costs. background. the aim of the study was to investigate: i) relevant and combined determinants of the development, management and outcome of a representative patient cohort (n ¼ . ) with acute appendicitis enrolled in a prospective unicenter study through a time period of years (middle europe), and ii) the frequency and impact of specific categories (e.g., characteristics of the medical history, clinical and intraoperative findings, complications), correlation and relative risk factors of the disease and its prognosis. methods. by the mean of a prospective unicenter observational study, numerous characteristics as mentioned in the ''aims'' were documented and influencing variables with significant impact on the outcome were statistically determined. results. ) the wound abscess rate was . %. perforation, surgical intervention on time, acute, gangrenous and chronic appendicitis, age, adverse diseases such as obesity, arterial hypertonus, diabetes mellitus, sex and missing pathological finding intraoperatively showed a significant impact on the postoperative development of a wound abscess. ) the longer the specific appendicitis-related medical history lasted, the i) more frequent a perforated appendicitis occurred (interestingly, this rate significantly increased up to . % through the various time periods), ii) greater the false-positive appendectomy rate was (p < . ), and iii) higher the rate of the required second (subsequent) interventions was ( . %; p < . ), which occurred significantly more often in obesity ( . %) and wound abscess ( . %). ) the mean postoperative hospital stay was days. ) there was a significant decrease of the percentage of patients with no pathological finding of the ''appendix vermiformis" intraoperatively, who underwent appendectomy, in particular, to only . % through the last investigation period from to ( - , . %; - , . %). ) the mortality was . % showing no significant difference between male and female patients (p ¼ . ), between the investigation periods (p ¼ . ) and between the patients with false-positive appendectomy ( . %) and that with acute appendicitis ( . %; p ¼ . ). conclusions. in summary, this study demonstrated a substantial progress of the quality of surgical care within the participating clinics with regard to the rates of false-positive appendectomies, of postoperative wound abscesses and, in particular, to mortality, one of the strongest criteria of quality control. despite this, there is an increasing rate of perforated appendicitis in the investigated cohort. in conclusion, quality control remains an indispensable tool for evaluation and assessment of surgical care even in the most frequent diseases of the daily practice, which can be further improved by a multicenter study setting. acute mesenteric ischaemia -looking at the past, learning for the future e. schröpfer, a. thiede, t. meyer background. acute mesenteric ischaemia (ami) is a rare disease with still -despite all progresses in medicine -a high mortality rate ranging from to % according to literature. the aim of this study was to analyse the outcome of our patients after traditional therapy, in order to be able to conduct new strategies of treatment. methods. in this retrospective study all clinical reports (since = ) containing the diagnosis ami (icd : k . ) were analyzed with regard to initial laboratory findings, pre-operative diagnostics, surgical methods, intra-operative results, etc. results. the diagnosis ami was encoded for patients in the aforementioned period of time. twenty patients had to be excluded from the study, due to other collateral diseases. among the remaining patients (with an average age of . years) died initially (initial mortality . %). the main risk factor ( . %) was arrhythmia absoluta. . % of the patients presented the symptoms of an acute abdomen, . % were suffering from progressive abdominal pain. besides anamnesis, physical examination and laboratory only . % of the patients obtained an abdominal ct and . % obtained a dsa. because of the unambigousness of the anamnestic and clinical findings . % of the patients received an immediate explorative laparotomy without any further diagnostic. conclusions. despite the typical triphasic progression of the ami (intense abdominal pain -apparent recovery -acute spreading peritonitis) and all modern possibilities of diagnostics the mortality rate of ami is still appallingly high. looking at the past, diagnostics as well as therapy should be included in modern findings and open up new possibilities. bckground. data are rare about the impact of infection on postoperative mortality in an unselected surgical population. aim of the study was to analyze whether infection is a significant cause of death in these patients. methods. at a department of general, vascular and thoracic surgery in a secondary to tertiary referral centre, all patients operated from = to = (n ¼ ) were included in a prospective database and analyzed retrospectively. overall mortality rate . % (n ¼ ( abdominal, vascular, thoracic surgery)). . % emergency - . % planned operations. cause of death was defined by clinical chart review and post mortem section. stratification criteria (sex, age group, asa, malignancy, infection prior to surgery, abdominal surgery, emergency operation) were analyzed by multivariate regression analysis. results. cause of death: n ¼ ( . %) infection, n ¼ ( . %) cardiovascular, n ¼ ( . %) progression of malignancy, n ¼ ( . %) pulmonary embolism. subgroup analysis of postoperative death due to infection revealed that . % (n ¼ = ) of patients had infection already prior to surgery and . % (n ¼ = ) developed postoperative lethal infection. mortality caused by infection was . % (n ¼ ) in abdominal, . % (n ¼ ) in vascular and % (n ¼ ) in thoracic surgery. regression analysis identified infection prior to surgery (p ¼ . ) and abdominal surgery (p ¼ . ) as statistically significant independent risk factors for postoperative mortality due to infection. conclusions. postoperative mortality is highly associated with infection. in an unselected cohort of surgical patients those presenting with infection prior to surgery and those undergoing abdominal surgery are at highest risk of death from infection. management of complications in laparoscopic colo-rectal surgery m. hufschmidt, u. obwegeser, a. haid, e. wenzl background. laparoscopic colo-rectal surgery is considered to be a standardized procedure for the two main-indications: diverticular disease of the sigmoid colon and complicated crohn's disease of the ileo-cecal region. moreover these procedures seem to have served as a sort of pacemaker to so-called fast-track-protocols. while the extension of laparoscopic procedures to oncological indications is in a wide-spread controversial discussion, only few publications are considering the impact of complications in the outcome of surgical therapy of benign diseases. methods. a retrospective study of laparoscopic colorectal procedures performed between = and = was undertaken. indications and technical approaches as well as rates of conversion, duration of intervention and hospital-stay are detailed. complications leading to relaparotomy, interventional or conservative therapy are reviewed in detail to analyse their reasons. results. with a conversion-rate of . %, a mortality of . % and an overall morbidity of . % the occuring complications may be categorised in different groups, distinguishing intra-operativly, early or late, major or minor and procedurerelated or intercurrent-ones solicitating either conservative, interventional ( . %) or surgical ( . %) treatment. several causes are being isolated such as learning-curve, body-mass-index, comorbidity, sequelae of previous operations and severity of intraoperative findings. conclusion. as for conversion, complications influence parameters as hospital-stay or feasibility of fast-track-protocols somewhat watering the advantageous results of laparoscopic colo-rectal surgery. a careful analysis is therefore advisable not only to avoid reiterating complications but also to permit the access to oncological colo-rectal laparoscopic surgery as well. background. the value of quality control in general surgery is actually soaring. unplanned reoperation is seen as one of the most important quality measures. however, there is a lack of data regarding the impact of infection as an indication to unplanned reoperation. methods. at our department of general (including kidney transplant), vascular and thoracic surgery in a secondary to tertiary referral centre, all patients undergoing unplanned reoperation from = to = were included in a prospective database. unplanned reoperation was defined as unplanned return to the or within days during hospitalization. targets were unplanned reoperation due to infection, type of infection, type of primary surgery, mortality and a comparison to a former data collection from = - = after starting a monthly review of reoperation data in terms of a morbidity-=mortality conference = . results. one hundred and thirty nine ( . %) of patients were undergoing unplanned reoperation. ( . %) due to infection, ( . %) due to postoperative bleeding and ( . %) due to other indication. subgroup analysis of those reoperated due to infection identified leakage of the anastomosis in % ( = ) and abdominal wall rupture in . % ( = ) as predominant causes to reoperation. other indications to unplanned reoperation were small bowel perforation ( = ), abscess ( = ), leakage of ileostoma ( = ), thoracical phlegmon ( = ), ureter-necrosis ( = ), recurrent infection of lung parenchyma ( = ) and superficial surgical site infection ( = ). mortality in the infection subgroup was . % ( = ) compared to . % ( = ) of all reoperated patients. overall mortality was . % ( = ). furthermore we could achieve a decrease of mortality in infection subgroup from to . % comparing to our former data collection of = - = . an additional analysis of infection germs was not striking. conclusions. postoperative infection is the underlying mechanism leading to reoperation in a significant number of patients. data analysis showed a much higher mortality in these patients. the reported decrease of mortality from to . % maybe attributed to the consequent prospective monitoring and monthly review of reoperation data we had introduced = . gallstone-ileus -nowadays still a remaining important differential-diagnosis to consider at presence of acute abdominal pain r. hammer , p. habertheuer , w. brü nner , c. bauer , n. schreibmayer , f. flü ckiger , p. steindorfer department of surgery, lkh graz-west, graz, austria; department of radiology, lkh graz-west, graz, austria background. - % of all mechanical obstructions in small bowel are represented by gallstone-ileus as a complication of cholelithiasis. as it is frequent in the elderly population (it accounts for almost % of non-strangulated intestinal obstruction in patients > years), there is a high mortality-rate of - % depending on age and co-morbidity. in less than % of patients with gallstones cholecystoenteric fistula occurs (most likely cholecystoduodenal in %, cholecystocolic, cholecystogastric-and cholecystodochoduodenal have also been described). methods. between october -december we performed cholecystectomy on patients and laparatomy on patients due to mechanical obstruction of the small bowel. the frequency of gallstone-ileus can be reported on patients, which underwent surgery due to intestinal obstruction because of gallstones. one recurrence of gallstone-ileus due to the lack of exploration on finding massive postinflammatory adhesions and adherence of the major omentum was seen. in all patients clinical evidence of intestinal obstruction detected pneumobilia as well as ectopic gallstones was confirmed by either plain x-ray or ct-scans. results. at our department a frequency of patients (average age . yrs (range - yrs) males, females) presenting with gallstone-ileus (in a total of patients undergoing cholecystectomy and patients undergoing laparotomy due to small-bowel-obstruction) were treated, that means a rate of gallstone-ileus in . % ( = ) compared to the patients with che, and . % ( = ) in laparotomies due to small-bowel obstructions performed at this period. all patients underwent an one-stage operation, in cases consisting of enterolithotomy and stone-extraction as single procedure only (without dismantlement and exploration of the fistula), in further cases cholecystectomy and suturing of the entero-biliary fistula synchronously were additionally performed. the obstruction occurred  duodenal,  jejunal and  ileal, the location of the fistula situated duodenal in times, once jejunal and  non-explored. the diameter of the obstructing stone varied between and cm (average of . cm), patients recovered well, one expired because of the development of ards. conclusions. gallstone-ileus is a rare diagnosis, nevertheless it should still be kept in mind and considered as important differential-diagnosis in acute abdominal pain as shown on the numerous cases at our department. for reducing perioperative mortality the treatment has to be adapted on patients conditions, if necessary performing enterolithotomy as a single procedure only, and considering to correct the fistula in a second procedure on symptomatic patients. in the program of the austrian surgical convention different working groups and specialised societies are listed up, stating that the specialisation in surgery is increasing. however, the question remains, which fields of specialisation are realistic for a general surgical department with a limited staff? in the last years a main focus of interest has been established for the following fields: endoscopy: gastroscopy, sigmoideoscopy, colonoscopy with interventions is performed by all, ercp by two surgeons of the staff. minimal-invasive surgery: choleystectomy, appendectomy, hernia surgery is performed by all surgeons, colon resections, gastro-oesophageal surgery by three of the staff. endocrine surgery: surgery of the thyroid and parathyreoid gland by three surgeons. specialized breast surgery: such as oncoplastic surgery and breast reconstruction by two surgeons. varicositas surgery: crossectomy and stripping, evlt, trivex, venocuff by two surgeons. the development of specialization in a general surgical unit will be presented. methods. review on cle. results. due to reflux esophageal squamous epithelium is damaged and replaced by cle, which is of esophageal origin and interposed between squamous and gastric oxyntic mucosa (om). the paull-chandrasoma histopathology cle classification includes oxyntocardiac (ocm; mucus and parietal cells) and cardiac mucosa (cm; mucus cells only) without or with intestinal metaplasia (im ¼ barrett esophagus). via low (lgd) and high grade dysplasia (hgd), im may progress towards eso-phageal adenocarcinoma (ac; annual incidence . - . %). presence of cle is associated with pathologic esophageal acid exposure and impaired esophageal motility and dysfunction of the lower esophageal sphincter, as assessed by ph monitoring and esophageal manometry, respectively. cle without and with im is assessed in and - % of symptomatic gerd patients, respectively, irrespective of presence or absence of endoscopic visible cle. surveillance endoscopy and biopsy sampling are recommended after - , - and . years for cm, im and lgd, respectively. treatment of hgd and ac stage ia include endoscopic mucosal resection or esophagectomy. esophagectomy is recommended for ac > stage ia. recent studies indicate that antireflux surgery may reverse im and low grade dysplasia (lgd). seven years after ph-monitoringproven effective (n ¼ ), but not ineffective (n ¼ ) nissen fundoplication, im reversed towards cm without progression towards ac. fourty months after nissen fundoplication and bile diversion (n ¼ ), % regressed from im to cm, % remained at im. . years after gastric bypass (n ¼ ), im-patients regressed (n ¼ ) or had im (n ¼ ), none progressed. a recent study compared the effect of proton pump inhibitor (ppi) (n ¼ ) vs. fundoplication (n ¼ ) in patients with cle containing low grade dysplasia (lgd). eighteen months after ppi treatment and fundoplication, out of ( . %) and all out of patients, respectively, reversed from lgd towards intestinal metaplasia. conclusions. cle is defined by histopathology. evidence justifies to investigate impact of effective fundoplication on cle within prospective studies. background. during endoscopy the stomach is considered to commence at the level of the rise of ''gastric'' rugal folds. anatomy studies suggested that rugal folds may contain columnar lined esophagus (cle), the morphologic consequence of gastroesophageal reflux disease (gerd). we investigated the histopathology of endoscopic ''gastric'' rugal folds in gerd patients. methods. seventy-five consecutive gerd patients ( males), age: ( - ) years, prospectively underwent endoscopy, including biopsy sampling from the endoscopic esophagogastric junction (egj): , . , . cm distal and . and . cm proximal to the rise of the rugal folds. cle was cataloged according to the histopathologic paull-chandrasoma classification. results. normal endoscopic esophagogastric junction, visible cle . and > . cm was assessed in ( %) and ( %) and ( %) patients, respectively. histology: all patients had cle at the level of rise of the ''gastric'' folds. in and % of patients cle extended . and . cm, respectively, distal to the rise of the rugal folds. gastric oxyntic mucosa was not assessed above the level of the rise of rugal folds. intestinal metaplasia (¼ barrett esophagus) was assessed histologically in ( %) patients. conclusions. regarding the diagnosis of cle, the esophagogastric junction (egj) cannot be assessed by endoscopy, but by histopathology (i.e. level of transition from cle towards gastric oxyntic mucosa). presence or absence of barrett esophagus can not be excluded by endoscopy. histopathology of multi level biopsy sampling should be considered for definition of egj and exclusion of barrett esophagus in gerd patients. pre-clinical trial of a modified gastroscope that performs a true anterior fundoplication for the endoluminal treatment of gerd background. laparoscopic fundoplication provides good reflux control but side effects due to the surgical procedure are known. different endoluminal techniques have been introduced but all with disappointing results. evaluation of the feasibility and safety of a new device, that enables a totally endoluminal anterior fundoplication for the treatment of gerd. methods. the device is a modified video gastroscope, which incorporates a surgical stapler (using standard . b shaped surgical staples) and an ultrasonic sight. the cartridge is mounted on the shaft and the anvil is at the tip. this enables accurate stapling of the fundus to the esophagus, using the ultrasonic sight to guide distance and alignment of the anvil and the cartridge. sixteen female swine of mixed breed were used in the study, underwent the endoscopic procedure, and were used a controls to monitor weight gain. the study animals were sacrificed at , , and weeks ( pigs each time) and visually inspected for complications, healing and fundoplication. the study was sponsored by medigus ltd. and monitored for compliance with glp regulations by an external company (econ inc.), which is glp certified by the german federal government. it was conducted at the animal testing facility of the charite virchow clinic in berlin. results. the procedure went smoothly in all pigs, median procedure time was min (range - min). at sacrifice the stapled area had healed well, all animals had a satisfactory anterolateral fundoplication, and there were no procedure related complications. conclusions. creating a satisfactory anterior fundoplication with the new device is feasible, easy, and safe. proof of efficacy must await clinical trials, which are underway. design and instrumentation of new devices for performing appendectomy at colonoscopy g. silberhumer , e. unger , w. mayr , t. birsan , g. prager , j. zacherl , c. gasche background. appendectomy is the most common operation in the gastrointestinal tract. there is increasing interest in interval appendectomy as a treatment for refractory ulcerative colitis. a less-invasive flexible endoscopic method for removing the appendix might offer advantages especially for interval appendectomy in patients undergoing colonoscopy. aim: to design, develop and test new devices for removing the appendix via natural orifice transluminal endoscopic surgery (notes). methods. tests were performed on the bench in colons from adult human cadavers. various prototypes were tested, which could be inserted into the appendiceal orifice to its tip and could invert the appendix at its base in a controlled fashion into the lumen of the cecum. the advantage of using a tubular structure as counter force to aid inversion of the appendix was evaluated. after partial inversion the growing strain was relieved by endoluminal incision of the mesenteric side of the appendix. closure methods with endoloops, clips and thread ties were studied. appendiceal resection was completed by snare diathermy leaving an inverted intraluminal stump. results. the position of the appendix was retrocecal in seven cases, pelvic in two, and pre-ileal or post-ileal in one each. the median length and luminal diameter was mm ( - mm) and . mm ( - mm), respectively. partial obstruction of the lumen was present in = cases. it was possible to advance the guide-wires and retraction devices to the tip of the appendiceal lumen in all cases. partial inversion of the appendix was successful in = tests. the median length of the inverted stump was mm ( - mm) . the tension and volume (due to fat deposit) of the mesoappendix was the main reason for incomplete inversion. complete inversion was achieved by endoluminal incision in = tests. the mean volume of the resected tissue (inverted appendix incl. its mesoappendix) was . ae . ccm. conclusions. despite high individual variability, appendectomy at flexible colonoscopy proved to be feasible and relatively easy. new devices to allow appendix inversion were successfully tested. endoscopic necrosectomy -a feasible and safe alternative treatment option for infected pancreatic necroses in severe acute pancreatitis (case series of patients) u. will , r. gerlach , i. wanzar , f. meyer department of gastroenterology, municipal hospital, gera, germany; department of surgery, university hospital, magdeburg, germany background. endoscopic necrosectomy of infected pancreatic necroses in severe acute pancreatitis is considered an alternative but minimally invasive treatment option instead of the more traumatic open surgery. the aim of the study was to investigate feasibility and outcome of endoscopic necrosectomy in infected organized pancreatic necroses (iopn). methods. through a -year time period, all consecutive patients with symptomatic iopn who underwent this novel endoscopic approach were prospectively documented in a computer-based registry and were retrospectively evaluated (systematic case series). the endoscopic approach comprised: . necrosectomy via the transgastric route under eus guidance; and (optionally). . additional a) transpapillary stenting of the pancreatic duct; or b) percutaneous drainage if indicated. feasibility was characterized by success rate (clearence=downsizing of iopn, hospital stay) and outcome by complication rate (frequency of bleeding or perforation), mortality and shortterm follow-up. results. from = = - = = , patients with symptomatic iopn (maximal diameter, - cm) who underwent endoscopic necrosectomy were enrolled in the study. sixteen of them ( . %) were necrosectomized from all nonviable tissue using - (range) necrosectomies (mean, . ). in = cases ( . %), iopn were incompletely removed. the pancreatic duct was drained through the papilla because of duct disruption or dilatation in = cases ( . %). a percutaneous drainage was placed into fresh, non-organized necroses or because of acute septic problems in = patients ( . %). complications occurred in = subjects (rate, . %): bleeding (n ¼ ) managed endoscopically; cardiac arrhythmia (n ¼ ); no perforation. at the time of discharge (mean hospital stay, . d), i) internal drainage was still in situ (range, - double pigtails) in = individuals ( . %), which was extracted in the post-hospital range of - d; ii) = patients ( . %) were asymptomatic indicated by normal inflammatory laboratory parameters; iii) = subjects ( . %) showed no further iopn whereas in = patients ( . %), there was a -fold (mean) down-sizing of iopn. one patient ( . %) died from cardiac infarction on the th day of hospital stay (intervention-related mortality, %). follow-up investigation (range, - d): = subjects ( . %) developed pancreatic pseudocyst, which was endoscopically approached. conclusions. endoscopic necrosectomy combined with endoscopic placement of a internal (transgastric) drainage or transpapillary stent into the pancreatic duct is a feasible and safe treatment option even in the case of extended iopn with large pieces of necrotic tissue. background. leakage and fistulization of the gastrojejunostomy have been the major drawback of gastric bypass surgery since its first description. most authors agree that operative treatment is the mainstay of therapy in all patients with signs of sepsis. however, intestinal contents causing localized infection may impede healing of sutured leaks in some patients and fistulas develop. as the anastomosis cannot be disconnected or exteriorized for anatomical reasons other forms of treatment have to be applied. results. leakage of the gastro-jejunostomy occurred in three patients after gastric bypass and resulted in formation of a fistula; one fistula developed in a patient days after surgery. coated self-extending stents were implanted endoscopically in all patients. enteral nutrition could be started six days later. stents were removed two months after implantation without problems. weight loss and quality of life after stent removal were excellent in all patients. conclusions. in our experience implantation of coated selfexpanding stents represents a very effective and minimally invasive therapy of gastro-jejunal anastomotic fistulas after gastric bypass when surgical repair is not possible. in these cases application of stents allows septic source control without any other intervention. methods. fetal mri studies were performed on a . t (philips) superconducting unit using a five-element surface phased-array coil, usually after th gestational week. no sedation is necessary. in addition to routine t -weighted (w) sequences, t w sequences (mainly to demonstrate meconium-containing bowel loops), t à w-sequences (in case of hemorrhagic lesions), steady state fast precession (ssfp) sequences (to depict vessel-abnormalities), dynamic ssfp sequences to show swallowing and peristalsis, flair and diffusionweighted sequences (for further tissue characterization) were done. results. one hundred and twenty-six fetuses with extra-cns malformations, prenatally examined with fetal mri, had postpartal or postmortal follow up at the medical university clinic of vienna: among these, congenital diaphragmatic hernias (cdh, ) could be selected for primary repair ( ) because of adequate lung maturity, with extreme lung hypoplasia underwent extra corporal membran oxygenation. cystic adenomatoid malformation ( ) and lung sequestration ( ) were diagnosed, requiring immediate postnatal or later repair. abdominal anomalies ( ): stenosis, obstructions or atresias of small bowel ( ) were treated by adequate therapy from the very beginning. anal atresias ( ) were differentiated into high and low forms, cases which needed colostomy or could be corrected in an one stage repair. nine gastroschisis ( ) and omphaloceles ( ) were delivered pretermly dependent on the amount of eventerated bowels. ovarial cysts ( ) were differentiated from abdominal tumors ( ), the latter requiring immediate surgery, the former only depending on size and content. urologic pathologies ( ) could often be treated conservatively. conclusions. the results of fetal mri do not have an impact on the type of surgical procedure. however, early accurate diagnosis of pathology, including information about vital functions (such as the degree of lung maturity) may influence the decision of the time to perform the operation, to achieve a most successful outcome for the patient. background. common bile duct (cbd) stones represent a diagnostic and therapeutic challenge in pediatric age group. the aim of the study was to evaluate our management of children with suspected cbd stones and to develop an algorithm for the rational use of perioperative ercp, mrcp and intraoperative cholangiography (ioc). methods. between and , children that had undergone laparoscopic cholecystectomy (che) were evaluated for preoperative findings suggestive for cbd stones, preoperative use of ercp or mrcp, use of ioc and findings during surgery. a diagnostic and therapeutic algorithm for cbd stones was developed. results. twelve children ( %) had preoperative findings suggestive for cbd stones. of the children with elevated liver enzymes and abnormal ultrasound findings, ( %) were identified to have cbd stones. five had preoperative ercp which detected and successfully cleared stones in patients. ioc identified cbd stones in children, including one patient with a preoperative negative ercp. of the children with either elevated liver enzymes or abnormal ultrasound, only one stone in the cystic duct was identified by a gall bladder edema in the preoperative mrcp followed by ioc. three children received preoperative mrcp and ioc was performed in . no retained stones were detected postoperatively. conclusions. cases with high suspicion for cbd stones should undergo a preoperative ercp followed by intraoperative cholangiography, if no stones could be found. in case preoperative findings are ambiguous, prevalence of cbd stones is low and we suggest mrcp or ioc as the diagnostic methods of choice. pure esophageal atresia with normal outer appearance -a new subtype? -case report m. sanal , b. häussler , w. tabarelli , k. maurer , c. sergi , j. hager background. isolated esophageal atresia (vogt type ii) is characterized by an agenesia of the midportion of the esophagus. this paper presents a case of such a form of esophageal atresia with a cm long fibrous segment between the two esophageal pouches resembling the subtype ii according the kluth's atlas. methods. thirty-seven week gestation boy born by uneventful vaginal delivery with g birth weight was transferred to our department because of inability to pass a nasogastric catheter. resection of the fibrous segment and primary anastomosis of the esophagus was performed succesfully. results. the postoperative course was uneventful and the patient was discharged on the postoperative day. histological examination of the atretic segment showed an haphazard distribution of not functional lumina and blood vessels. conclusions. kluth has described ten types of esopageal atresia in his atlas; pure esophageal atresia is classified as type ii in which the proximal and distal segments are atretic without a tracheo esophageal fistula. matsumoto described a subtype in which the midportion of the esophagus is atretic and there is a cyst located in the atretic strand. loosbroek also described in a new type of isolated esophageal atresia that included double membranes with a cm gap between them. we describe here a similar case of pure esophageal atresia, showed neither a cyst nor a membrane. extensive review of the literature failed to disclose any similar case showed this kind of histological character. we report our experience with the minimal invasive method of surgical reconstruction of pectus excavatum recurrence. since at our department pectus excavatum patients have been operated on by the modified minimally invasive method of reconstruction (modified nuss technique). seven patients aged . ae . showed a severe recurrence ( patients after ravitch-welsh-rehbein method primarily operated elsewhere, one after explantation of the ''nuss bar'' operated in our department). five patients suffered on reduced physical effort and patients aim for a better cosmetic result. preoperative investigations include blood samples, ecg, heart sonography, chest x-ray, chest mri=ct with -d reconstruction and spirometry. the following intraoperative events deserve mention: . severe retrosternal scarred tissue complicate the retrosternal preparatory mobilisation of the pericardial sac and the sternal portion of the diaphragm n ¼ . . intraoperative thoracoscopy showed pleural adhesions which were divided thoracoscopically n ¼ . . non compliant stiff thorax due to sternal kinking and=or ossification of the regenerated ribs after ravitch procedure made the following procedures necessary: a. additionally osteotomies of the ossificated ribs (n ¼ ). b. implantation of a second bar (n ¼ ). c. an oblique wedge shaped partial sternal osteotomy (n ¼ ). due to preparation we had intraoperative bleeding episodes of the internal mammaric vessels, lesion of the pericardial sac (scar tissue) and superficial lesion of the right visceral pleura (adhesions). vertebral index changed from preoperatively to a normal range of postoperatively. postoperative cosmetic results were perfect in %. in summary cases with pectus excavatum recurrence are manageable with extremely satisfactory results using the described extended modified correction technique. osteotomies do not destabilize the chest and can be sufficiently combined with the nuss technique. background. former surgical approaches to laparoscopic repairs of morgagni hernias in children involved pros-thetic as well as nonprosthetic repairs. we simplified a nonprostethic laparoscopic method to an easily feasible procedure. methods. two boys with retrosternal diaphragmatic hernias (morgagni) underwent primary laparoscopic repair. a nonabsorbable suture was inserted directly through the anterior abdominal wall and the hernia was tightened in a lateral to medial fashion by a continous suture and tied in the subcutaneous tissue of the xiphoid region. results. two boys, months and five-year old, with coincidentally diagnosed bilateral retrosternal diaphragmatic hernias (morgagni), underwent laparoscopic repair of their hernias. they had an uneventful postoperative recovery, apart from a port site hernia in one. conclusions. this technique for primary laparoscopic repair of morgagni hernia is safe and easy to perform. laparoscopic closure of the defect by suturing the posterior rim of the hernia to the anterior abdominal wall with a continous nonabsorbable suture provides a safe and effective therapy for this type of diaphragmatic hernias. our experience of post-natal diaphragm paralysis treatment in newborns a. kuzyk , a. pereyaslov , r. kovalsky , o. leniv background. the paralysis of right cupula of diaphragm in newborns in many cases is the result of birth trauma and is indicated as erb-duchene syndrome. the paralysis declares itself by the high standing of diaphragm and its paradoxical movements during respiration, displacement of mediastinum and lung compression which bring to heavy respiratory distress, cardiovascular insufficiency development and requires artificial pulmonary ventilation in first post-natal hours. methods. in the period of - , children with post-natal paralysis of diaphragm right cupula and child with post-natal paralysis of diaphragm left cupula have been treated in our clinic. the body weight at birth was - g. the basic symptoms were: hard respiratory distress and cardiovascular insufficiency, pulmonary hemorrhage, depression of the central nervous system. two children with low body weight had been on artificial pulmonary ventilation during period from the birth to surgical treatment. conservative therapy was done from to . months without positive clinical effect -respiratory insufficiency had not been reduced, the children had retarded in physical growth and development. all children were operated on diaphragm goffering from thoracotomy on the affected side. results. after surgery all patients needed artificial pulmonary ventilation during - days. with good clinical results all children were discharged from the hospital. conclusions. the newborns with post-natal diaphragm paralysis with not effective treatment during - weeks needed surgical correction -diaphragm goffering on the affected side. long term experience with the paulprocedure in a large animal model background. this study was designed to assess the long term efficacy of the paul-procedure for abdominal wall defect repair in a large animal model (lam). methods. we created  cm full-thickness abdominal wall defects in goettinger miniature piglets (n ¼ ; body weight: . - . kg). the defect was repaired by the paul-procedure, using an extracellular matrix of xenogeneic origin as an interpositional graft. a weekly examination of the animals followed, including measuring of bodyweight and observation the possible development of a hernia. additional the abdominal cavity was evaluated laparoscopically at , , and months after paul-procedure. the adhesions to the intestine were measured and the neo-abdominal wall was taken for histological examination. results. ( ) the paul-procedure could be performed technical easily in lam. ( ) background. gastroschisis is a relatively rare congenital anomaly in which eviscerated fetal abdominal organs are exposed to amniotic fluid in utero through an anterior abdominalwall defect. since the first surgical treatment of gastroschisis by fear in the evolution of therapeutical concepts is steadly proceeding. methods. a retrospective study enclosing all children with gastroschisis treated at vienna general hospital from to was carried out using patient charts. statistics was performed using spss . . the results are compared with the literature. results. fifty-five children with gastroschisis were treated. birth was performed between and week of gestation ( % caesarean section). diagnosis was established between and week of gestation. in % of the patients primary surgical closure was performed. oral feeds were started on . day, mechanical ventilation was stopped after . days. twenty children developed infection=sepsis=pneumonia ( . %) children developed ileus=perforation=vovolus=nec=patch infection ( . %). thirty four children had single gastroschisis related surgery ( . %), secondary surgery up to operations. mortality was . % ( deaths). conclusions. since bianchi's publication of minimal intervention management for gastroschisis in traditional surgical concepts have often been questioned. our results are comparable with international data. although very tantalizing there are no large prospective randomized multicenter studies that show clear superiority of one or another strategy. epidemiologic data show an increasing incidence of gastroschisis which shows the importance of standardized successful procedures for the future. background. colorectal cancer is one of the most common cancers in western countries with incidence rates that are quite stable through the last years. while surgical therapy with high central vessel ligation and adequate lymph node dissection seems well standardised -in laparoscopy as well as conventional surgery -great efforts have been made in new adjuvant treatment strategies and in treatment of colorectal liver metastases. methods. we report about a consecutive series of more than patients treated with colorectal cancer since . . . data about epidemiology, localisation of the primary, surgical methods, tumor classification, complication and mortality rates and survival will be presented in detail. results. the median age was years, % of the patients were more than years old, . % were female. fifteen percentage were treated with an acute onset like ileus or perforation. thirty five percentage had right sided primary, hartmann procedure was performed in %. about % of patients were operated as stage (uicc), the year survival rates of all groups including stage was %. pathohistological assessment showed % r resections (stage included) and a median lymph node count of (pn). perioperative mortality was %, complication rate with the necessity for at least surgical reintervention was . %. conclusions. we demonstrate that surgical therapy of colorectal cancer is safe and effective in terms of oncological outcome and perioperative morbidity and mortality, although colon resections in our department are typical teaching operations. modern anaesthesia and intensive care allows radical oncological surgery even in the elderly. interdisciplinary treatment keeps its way, exact pathohistological processing and cooperation with the pathologist still is the most important factor in quality assessment of oncology surgery of the colorectum. background. although adjuvant -fu-based chemotherapy showed to increase -year survival in stage iii colon cancer, the role of adjuvant chemotherapy in stage ii colon cancer is still unclear. p , a frequently mutated tumour suppressor gene needed for correct induction of apoptosis, is a promising marker to define subgroups of patients who benefit from adjuvant chemotherapy in stage ii colon cancer. methods. in order to evaluate the clinical relevance of p mutations, we investigated stage ii colorectal tumor biopsies from a previous randomised study of adjuvant chemotherapy, who were randomly assigned to adjuvant chemotherapy or surgery alone. for detection of p mutations we used singlestranded conformation polymorphism analysis. results. p mutation was detected in ( %) of informative tumor dnas. when receiving -fluorouracil-based adjuvant chemotherapy, patients with p mutation turned out to have a significant better disease-free -year survival ( . vs. . %, p ¼ . ). in contrast, when assigned to the surgery alone group there was no significant difference in -year disease-free survival between patient with p mutation and patients with wildtyp p . the difference between the patients receiving chemotherapy as compared to those which did not in respect to the presence of p mutations was significant (p ¼ . ). conclusions. in our patient cohort patients whose cancer had a mutation of p had a significantly better benefit from -fluorouracil-based therapy, what is contrary to previous observations. this discrepant result emphasise the need for a standardisation and validation of the methodology, patient selection and interpretation of clinical data before any prognostic marker can be routinely used. is tme an adequate treatment for low rectal cancer? p. lechner, g. humpel background. two patients who had had neo-adjuvant chemotherapy followed by surgery for cancer in the lower rectum presented with metastases in pre-aortic lymph-nodes after and months, respectively. this rose our suspicion that distant spread may in some cases follow the lymphatic vessels along the aorto-iliac axis. methods. after having performed very low anterior or even abdomino-perineal resection for cancer in the lower third of the rectum, biopsies are taken from nodes at the pelvic wall, along the iliac arteries, and the aorta. these are all compartments that remain untouched during routine tme. results. in one out of four patients we find at least one of the above mentioned groups of nodes to be involved. this is most often the case in patients, in whom the mid rectal vascular bundle requires ligation on at least one side. so there are obviously metastases that cannot be detected during the pathological work-up of the tme-specimen. twenty five p.c. of the patients considered to be n-o are already in dukes' stage c, thus requiring additional treatment. these findings -confirmed by the recent literature -suggest, that metastases may arise via lymphatic vessels along the mid rectal arteries and -further onalong the aorto-iliac vessels. conclusions. after standard tme for low rectal cancer lymph node biopsies should be taken in order to avoid understaging of the disease and to allow accurate patient stratification in clinical trials. transanal endoscopic microsurgery for rectal carcinoma: own experiences after cases p. patri, r. schmiederer, a. tuchmann background. transanal endoscopic microsurgery (tem) is an one access technique for local excision of rectal tumours using gas dilatation of the bowel and a stereoscope for unrestricted vision on the operation field. the tem-technique was invented by buess, theiss and hutterer and has been performed at our department since . sessile benign adenomas of the rectum inappropriate for colonoscopic resection represent the vast majority of cases indicated for tem-procedure, using the advantages of sphincter preserving resection in all thirds of the rectum without considerable access trauma. furthermore, tem can be applied to a highly selected group of rectal carcinoma patients in curative objective, including t g or g l v lesions, classified as low risk carcinomas after hermanek's criteria for malignant potential, with recurrence and -yearsurvival-rates equal to radical surgery. under palliative purposes tem can be considered in more advanced carcinomas such as high risk carcinomas (t g ) or in t - carcinomas without stenosis in patients with high risk for general anaesthesia, rejection of stomal construction or present distant metastases. methods. from = until = tem procedures were performed in patients, males, females, mean age was . years ( - ), the median hospital stay was days . following diagnoses were included: rectal adenomas (n ¼ ), rectal carcinomas (n ¼ ), carcinoids (n ¼ ), fistulas (n ¼ ), gist (n ¼ ) and melanoma (n ¼ ). all patients underwent tem-procedure as described by buess et al., the median operation time was min ( - ). highlighting the carcinoma patients regarding to postoperative histopathology tem was performed in n ¼ tis-lesions, n ¼ t low risk carcinomas, n ¼ t high risk carcinoma, n ¼ t and n ¼ t carcinomas. results. in carcinoma patients undergoing tem for curative objective recurrence rate was . %. if tem was performed in primarily palliative intention recurrence rate was %. no conversion to open technique had to be performed, no postoperative surgical complications were observed, one patient died weeks postoperative due to liver failure following esophageal varices bleeding. conclusions. transanal endoscopic microsurgery is a technically highly demanding but excellent procedure for curative therapy of rectal adenomas and low grade early carcinomas. furthermore, tem is feasible in more advanced carcinomas for palliative purposes. besides the technical advantages the procedure can prevent patients of rectal resection or stomal construction. background. anastomotic leak is the most feared early complication in the postoperative period after low anterior resection. the incidence varies between and %. use of tme technique lessens the percentage of local recurrences but increases the incidence of an anastomotic leak. a surgeon has to assess the risk factors and decide whether to create a protective stomy that protects the patient from fatal consequences of an anastomotic leak. methods. one hundred and three patients who had a low anterior resection without a protective ileostomy in the period - were included in the analysis. data of those who developed an anastomotic leak and those without were compared and the connection between specific risk factors and the incidence of an anastomotic leak was assessed. results. eleven patients ( . %) developed a clinically confirmed anastomotic leak. death after low anterior resection occurred in cases ( . %), in two cases in patients who developed a leak, resulting in a . % mortality rate for anastomotic leakage. there was no difference between males and females (p ¼ . ) and age groups (< vs. > years), (p ¼ . ). tumor localization in the lower third of the rectum was roughly showing statistical importance (p ¼ . ). the stage iv. of disease showed obvious connection (p ¼ . ). connection between the anastomotic leak and preoperative radiotherapy or high asa score (> ) was not established (p ¼ . and p ¼ . ). conclusions. the incidence of an anastomotic leak was comparable with results of other studies. localization of a tumor in the lower third in advanced disease represents an important indication for protective ileostomy. background. while adverse events occur in up to ten percent of all patients admitted to hospitals sentinel events do not happen often. however, these events represent great risks for medical institutions and persons involved. a thorough analysis of sentinel events is mandatory and can be achieved by root cause analysis (rca). methods. root cause analysis has been designed in order to assess underlying human, technical, and organizational factors contributing to adverse events. rca has to be performed in a standardized way by a team approach. the main goal of this analytic technique is to establish a relationship between causal factors and events under systemic aspects. after identifying incidental findings causal statements are formulated and actions are developed. conclusions. root cause analysis is a standardized investigative technique which allows to identify causes of severe adverse events and to develop preventive actions for the future. background. thyroid surgery can be followed by typical complications i.e. recurrent laryngeal nerve injury, postoperative hypoparathyreoidism and postoperative haemorraghe. refined surgical technique has improved the outcome and lowered the risk of complication to a minimum. methods. we analyzed global outcome and individual performance in more than , thyroid operations. the complication rates were compared in consecutive periods representing different surgical techniques and individual surgical performances. the data were repeatedly presented to the surgeons. the effect of this quality control procedure was reevaluated. results. exposure of the recurrent nerve and the parathyroid glands significantly reduced the global rate of post-operative=permanent rlni and hypoparathyreoidism. some but not all surgeons improved their results by recurrent nerve dissection (e.g., permanent rlni rates ranged from to . %) and refined dissection of the parathyroid glands (e.g., parathyroid insufficiency ranged from to . %). global outcome and individual performance were compared in periods and presented to the surgeons. the effect of this quality control procedure and the selective improvement of outcome will be shown by data. the extent of resection and the individual refinement of surgical technique was the source of variability. conclusions. refined surgical dissection significantly reduces the risk of complications in thyroid surgery. quality control can improve the global outcome and identify the variability in individual performance. this cannot be eliminated by merely confronting surgeons with comparative data; hence, it is important to search for the underlying causes. recent developments in medical litigation and liability in austria d. schaden , j. pritz krankenhaus der barmherzigen brüder, graz, austria; amt der steiermärkischen landesregierung, graz, austria the recent medical judgements of the highest court (e.g.: wrongful birth ogh ob = h) have been debated very controversially in medical profession and have attracted closer attention to the legal aspects of medical documentation and enlightenment. particularly in the surgical disciplines the patient should be made fully aware and get a detailed information about the risk of treatment failure, possible complications, limits to the procedures and long term outcome. exact information by the doctor is the condition necessary for the patient to give valid consent to the treatment and to avoid medical negligence litigation in these risky specialties. unfortunately these often for the doctors existentially important aspects are not part of the medical or surgical training nor are there any compulsory guidelines of medical enlightenment in the austrian legal practice which creates widespread individualism in all disciplines. we want to give an overview of the latest medico-legal lawsuits and judgements and their consequences for the daily working routine focussing on issues that can result in a doctor or facility being sued. background. every patient has the right to be informed about the consequences of surgery enabling him to give his informed consent. until recently the process of giving this information was not well organized. in the context of improving quality control at the hospital, a uniform process for patient information was established and the training of interns for giving informative talks was standardized and intensified. to measure whether these changes are reflected by an improved patient satisfaction, patients were surveyed before and after the changes. methods. two surveys were performed on patients before and after the improvements were introduced, and the results were compared. results. in each survey and questionnaires were returned. with the improved process the number of patients satisfied with the length of the informative talk rose ( - %, p < À ), less patients wanted a more detailed talk ( - %, p ¼ . ) and more patients considered the sketches on the informed consent protocol helpful ( - %, p <  À ). fewer patients thought the surgery was worse than expected ( - %, p ¼ . ). conclusions. using the new information process, a measurably better patient satisfaction could be observed. thus, by relatively simple means a highly efficient information process can be established even at a large hospital. the discontented patient j. pritz , d. schaden the number of claims after surgical procedures (not only bariatric or cosmetic surgery) is still increasing and patients nowadays are getting better informed about medical malpracti-ce=error in the media and the various possibilities to assert their rights. in austria various kinds of out-of-court settlement are installed to facilitate patient's compensation without the risk of litigation. in many cases misconceptions in the patient-doctor relationship can be solved without motion to court. but how can the terms ''malpractice'' or medical error be defined at all? which conditions must be fulfilled for the motion to court or the medical arbitration committee? we want to give a survey of the activity of the arbitration committee, the members, and the possibilities of compensation. moreover, the different consequences between criminal and civil law should be explained. the role of the expert witness, the course of procedure at the arbitration committee and possible consequences for the doctor or the facility will complete the presentation. background. negative resection margins are significant for prevention of recurrence in liver surgery. preoperative d models of imaging data provide significant improvements for visualization and planning, but intra-operative realisation is still a challenge. possibly navigation technology can improve oncological safety in liver resections. methods. fifty-four of liver resections for liver metastases were selected for intra-operative navigation due to complex anatomical situations. exact surgical plan was documented on virtual d models. planned resection margins were assessed and measured preoperatively. intra-operative d ultrasound data were acquired and localized with an optoelectronic tracking system, thus navigation of surgical instruments was provided in a virtual environment of these registered ultrasound data. surgical resection margins were compared with the surgical plan. results. navigated surgery was realized in of resections. r resection was achieved in of patients. mean histological resection margins were ( - ) mm. maximum deviation from the surgical plan was mm. conclusions. d ultrasound-based optoelectronic navigation is a feasible device for liver surgery, provides optimal anatomic orientation and can realize precise resection margins. background. during liver resection, a low central venous pressure plays a crucial role in reducing blood loss and intra-as well as post-operative morbidity. however, excessive volume restriction could lead to microcirulatory impairment and organ hypoperfusion. in the present study, we evaluated a standardized intra-operative protocol for optimal fluid replacement therapy. methods. in a prospective study, patients for elective liver resection were included. intra-operative fluid replacement was restricted to ml=kg=h in patients with thoracic epidural analgesia or ml=kg=h for patients without thoracic epidural analgesia. following target parameters were defined: central venous oxygen saturation > %, intra-operative lactate levels < mmol=l, urine output > ml=h, central venous pressure < mbar, and norepinephrine dosage < . mg=kg=min. in patients where at least one of the parameter values exceeded the predefined limit, fluid replacement therapy was intensified and dobutamine . mg=kg=h was started. patients were monitored for intra-operative blood loss, intra-and post-operative complications, and length of hospital stay. results. patients that remained within the intra-operative target parameters for central venous oxygen saturation, lactate levels, urine output, central venous pressure, and norepinephrine dosage had lower blood loss, fewer complications, and shorter hospital length of stay. conclusions. the standardized protocol is a good approach for optimal intra-operative fluid replacement and to minimize blood loss, post-operative complications and hospital length of stay. background. bile duct injuries (bdi) are still the most feared complication of laparoscopic cholecystectomy. the patient has to face prolonged postoperative treatment, even life threatening complications; the hospital and the surgeon rising costs and pricely and possibly time-consuming malpractice procedures. the repair of bdi requires special hepatobiliary expertise, but the long-term results even in the best centres are still sobering. there are different types of bdis requiring a tailored approach. we analyzed predisposing factors and types of bile duct injuries treated in our institution. methods. we analyzed our operative and endoscopy database from - for patients treated with bile duct injuries after cholecystectomy. bile duct injuries were classified according to a system proposed in by siewert and colleagues. results. between and a total of cholecystectomies were performed at our institution. there were laparoscopic (lc) and open procedures (oc; inculuding procedures with conversion from lc to oc); during the same period, patients ( females= males, mean age years; range: - ) were treated for bile duct injuries; of these patients were initially operated in an other hospital. there were patients with class i lesions (bile leak of the cystic duct or lesion of luschka ducts), patients with class ii leions (stricture of the cbd). two patients with class iii injuries (incomplete trans-section of the common bile duct) and patients with class iv lesions (transsection of the cbd or chd). thirty four of the initial ( % -all open and converted and laparoscopic) operations were considered difficulty by the surgeon performing the cholecystectomy. of operations were laparoscopic ( - %), converted from lc to laparotomy ( %) and laparotomy from the incision ( - . %). of the original operations, had been performed by an experienced surgeon, by a novice. conclusions. cystic duct leakage is still the most common type of biled duct lesions after cholecystectomy. bile duct injuries occur a s commonly in operations performed by by novices as in procedures done by experienced surgeons. in order to present the current concept for treatment of bpl patients suffering from traumatic brachial plexus lesion (bpl) who underwent microsurgical reconstruction were analysed. within one year in our institution male patients, aging from to years were scheduled for surgery. three suffered from complete, from upper bpl. six patients were diagnosed as supraclavicular lesions and as infraclavicular lesions. patients with diagnosed supraclavicular lesions were scheduled for surgery between and months after trauma. surgical exploration revealed root avulsion and or rupture in all cases. classic intraplexual reneurotisation was performed in patiens, whereas all patients received extraplexual reneurotisation procedures, utilising the spinal accesssory, the ulnar and intercostal nerves. three patients received secondary reconstructive procedures. patients with infraclavicular lesions were treated surgically between and months after injury. in all patients nerve grafts were used to reconstruct the injured fascicles, a nerve transfer was used in case only. one patient required secondary reconstructive surgery. the reconstructive strategy in bpl surgery has been changed dramatically during the last years. the strategy changed from a single surgical intervention one year after the trauma to a prozessual concept consisting of early primary nerve reconstruction and secondary reconstructive procedures. nerve grafting with use of autologuous nerve grafts for ''intraplexual'' reconstruction is still state of the art, additionally nerve transfers were introduced to utilize ''extraplexual'' sources for reeinnervation. regarding this concept most of the patients regain not only some motor function but functionality of their impaired upper extremity. teaching means learning -who benefits from academic teaching duties? p. lechner, g. humpel background. in the department of surgery at the danube clinics intulln, a level i hospital, has been named a teaching institution associated with the vienna medical university. this has certainly led to various organisational changes the results and consequences of which we attempt to identify. methods. all teaching institutions are subject to continuous evaluation by the students. in addition to that, we undertook an extra evaluation aiming at potential organisational and medical improvements from which patients, personnel, and students may benefit. results. ) as the students are available only from . through . o'clock, all organisational routines at the department (staff-rounds, meetings, lectures, etc.) now follow a more rigorous daily schedule. ) bed-side teaching means explaining everything that is undertaken in the presence of the patients. so the patients receive more information on their diseases and treatments. ) students tend to question everything, and so we also call in question many routines ''that have always been performed like that''. this allows us to simplify numerous operating procedures and means continuous organisational learning to the institution. ) for the same reason lecturers -and all those who are involved in teaching (physicians, nurses, and others)have to keep their academic knowledge up-to-date any time. ) teaching during meetings and ward rounds is of course not ''limited'' to university students, but also comprises interns and residents. conclusions. the department's current status as an academic teaching institution turned out beneficial for patients, personnel, and students, concerning professional, technical, and organisational aspects. though the additional workloadespecially in the beginning -must not be under-estimated, the advantages clearly exceed the burdens. background. necrotizing enterocolitis (nec) is the most common gastrointestinal complication of prematurity at the neonatal intensive care unit. the first aim of the study was to investigate the correlation between clinical parameters, extent of disease and mortality, and the second purpose was to analyse the surgical procedures and their outcomes. methods. in a retrospective study we reviewed medical charts of patients who were operated within a five years periode. preoperative blood results and demographic data were collected and evaluated. according to the extent of disease, birth weight and operative procedure different groups were analysed. results. a total number of patients underwent surgical procedures for nec from to , and % (n ¼ ) weighted less than g. in patients focal disease, in patients multifocal disease and in children panintestinal disease were found. preoperative blood tests revealed a median crp level of . mg=dl (normal range . ), median wbcc of . g=l and a median platelet count of g=l. primary laparotomy with defunctioning enterostomy was performed in %. overall mortality was %. conclusions. the extent of disease and the condition of the infants still determines the survival. preoperative blood results are of limited prognostic value. primary laparotomy with defunctioning enterostomy was the preferred technique in our unit, and even in the group of vlbw and elbw neonates surgery was well tolerated. discussion regarding the best operative procedure is still going on and no consensus in the management of nec is agreed on. methodik. während der letzten jahre wurden neugeborene (gestationsalter - wochen, geburtsgewicht - g, alter bei der darmperforation - tage) mit einer oder mehreren dünndarmperforationen beobachtet. die symptome waren jeweils etwa ident: abdominelle distension mit verfärbung der flankenhaut bei initial insgesamt stabilem allgemeinzustand. bei ,,nur'' der kinder zeigte sich im abdomen-leer-röntgen freies gas in der bauchhöhle, bei allen aber war sonographisch intraabdominell freie flockige flüssigkeit festzustellen, ohne nec-typische veränderungen am intestinaltrakt. kinder wurden aufgrund ihres schlechten zustandes nur punktiert=drainiert und antibiotisch behandelt. patienten wurden laparotomiert: bei kindern fand sich die perforation im bereich des jejunum, bei weiteren im unteren jejunum=oberen ileum und bei im terminalen ileum, davon hatte eines und eines perforationen. der betroffene darmabschnitt wurde jeweils reseziert; bei kindern wurde eine end-=end-anastomose durchgeführt, bei den verbleibenden patienten wurde wegen der peritonitis eine doppelläufige enterostomie angelegt. eines dieser kinder verstarb aufgrund einer sepsis-bedingten gerinnungsstörung. eines der beiden drainierten kinder wurde wochen nach der intervention wegen eines ,,verwachsungsbauches'' adhäsiolysiert. ergebnisse. die Ü berlebenschance sehr kleiner frühgeborener nahm während der letzten jahre deutlich zu. parallel dazu mußte bei diesen kindern eine zunahme umschriebener, ätiologisch nach wie vor nicht ganz geklärter darmperforationen zur kenntnis genommen werden. zur behandlung stehen grundsätzlich differente vorgehensweisen zur verfügung: im vordergrund steht eine resektion des lädierten darmabschnittes und, abhängig von den lokalen gegebenheiten (peritonitis ja=nein), entweder eine end-zu-end-anastomose und=oder nur eine doppelläufige enterostomie. als zweite prinzipielle therapieform gibt es die möglichkeit, die bauchhöhle zu punktieren= drainieren, wodurch die affektion auch beherrscht werden kann; im einzelfall kann sie letztlich aber doch nur chirurgisch zu sanieren sein. dieses vorgehen gilt für uns als ultima ratio. schlussfolgerungen. auch wenn eine isolierte darmperforation bei einem kleinen frühgeborenen relativ gut behandelbar ist, sollte durch klärung ihrer Ä tiologie eine prävention dafür möglich werden, da diese kinder wegen ihrer kritischen voraussetzung bereits per se außerordentlich gefährdet sind. the endorectal pull-through procedure (erpt) for hirschsprung's disease g. schimpl background. whereas in the past various operative techniques in patients with hirschsprung's disease (hd) were used, erpt was introduced as a single-stage operation. methods. sixteen patients with hd ( females, males) aged months to years were treated using the erpt procedure and the level of bowel resection was determined by intraoperative biopsies. results. the length of hd was in patients up to the sigmoid colon, in patients up to the transverse colon and one patient had a total colonic hd. two patients required a laparoscopic mobilisation of the left colonic flexure. in the patient with total colonic aganglionosis, the resection of the entire colon and sauer's procedure was performed using a periumbilical laparotomy. oral nutrition was started in all but on the first post operative day and they were discharged after - days. complication occurred in two patients: one had to be reoperated due to misinterpretation of intraoperative biopsies and a second patient with years of age developed a retrorectal abcess which was treated coservatively. in a follow-up, - years postoperatively, all patients are continent and have normal bowel movements. conclusions. erpt is an advance in the treatment of hd and can be performed at any age. it avoids the creation of enterostomies, is a single step procedure with excellent functional results and low complication rates. in long segment hd this procedure can be combined with laparoscopic or open surgical procedures. single-port appendectomy in obese children -a useful alternative? t. petnehazy, h. ainoedhofer, s. beyerlein, j. schalamon background. the rapidly increasing prevalence of obesity among children poses challenging problems in abdominal surgery. there is a growing body of evidence that single-port appendectomy (spa) is a feasible and safe alternative to open appendectomy (oa). very little is known about the clinical outcome of spa in overweight children. we present our experience with the treatment of suspected appendicitis in obese children using spa. methods. from january to december we performed spa in obese children with suspected appendicitis ( females, males, median age of . years). obesity was defined as a bmi > th percentile for age and gender (median weight . kg). in the procedures a -mm instrument was introduced through the umbilicus (combination of a -mm wide angle optic with -mm working channel). after exploration of the abdominal cavity and meckel's search, the appendix was exteriorized through the umbilical trocar and removed by open technique. patients' records were evaluated regarding anaesthetic time, complications, time until reintroduction of solid diet and histopathological findings. results. average operating time was . min (range - min). neither intra-nor postoperative complications occurred. reintroduction of solid diet to all patients was possible on the first postoperative day. the histology is presented in the below table. our results indicate that the advantages of spa such as: excellent evaluation of the peritoneal cavity, minimal rate of intraoperative incidents and superior cosmetic results make this technique a valid alternative for the treatment of appendicitis in obese children. background. ovarian torsion is a surgical emergency. because of unspecific clinical findings, diagnosis can be delayed and therefore may result in oophorectomy. recently preservation of ovarian function by means of laparoscopic detorsion has been proposed even in advanced cases. methods. we retrospectively reviewed patients with diagnosis of ovarian torsion who presented at our institution between and . a total of ovarectomies and detorsion were performed. twenty patients underwent minimal-invasive surgery, in cases laparotomy was performed. in cases a conversion was necessary. the accuracy of preoperative imaging modalities, surgical technique, correlation with postoperative histopathologic findings, complications and outcome were assessed. results. all patients were investigated by means of ultrasound. mri was applied in patients whereas ct-scan was done in patients. histopathological and intraoperative findings revealed simple torsions, twisted cysts and twisted teratomas. sensitivities to detect ovarian torsion were % for ultrasound (us), % for mri, and % for ct. entirely oophorectomies and detorsions in patients were performed. one of these patients presented with asynchronous bilateral ovarian torsion caused by a unilateral benign teratoma. in patients a laparoscopic contralateral oophoropexy was done. mean hospital stay was (laparoscopic) versus days (open approach). the complication-rate was marginal in both groups. conclusions. preoperative imaging is essential to improve the diagnostic accuracy. however, sensitivity only approaches %, emphasizing the importance of surgical exploration when symptoms are compatible with torsion. when a neoplasm is suspected, mri or ct imaging is essential. in order to preserve ovarian function and fertility, laparoscopic detorsion without primary resection should be the procedure of choice. it constitutes an easy, quick and equally safe procedure. the need for contralateral oophoropexy has to be discussed. background. differential diagnosis of lower abdominal pain include beneath common causes such as appendicitis and gastrointestinal infections some not so common diseases as ovarian pathologies in female patients. this may be ovarian cysts but can also be pathologies like ovarian torsions or tumours that have to be operated. however, the differential diagnosis between ovarian cysts and ovarian torsions is often radiologically inclonclusive and therefore makes a surgical intervention mandatory. methods. we analysed retrospectively the data from female patients hospitalised for ovarian pathologies in between and . twenty nine patients underwent surgical intervention for different causes. results. most patients presented with acute abdominal pain demonstrated signs of peritonitis and required pain relief. on the other hand we had patients with only mild clinical signs such as newborns with already prenatally diagnosed ovarian cysts. we found in our patients cases of benign ovarial cysts, cases of benigne teratomas, cases of serous cystadenomas, case of serous cystadenofibroma, case of yolk sac tumor and cases of ovarial torsions. conclusions. diseases of the ovaries are a rather rare but important cause of lower abdominal pain in children and adolescents and requires a mediculous diagnostic procedure and often an urgent surgical intervention. background. adrenal tumors, other than neuroblastoma, are rare in children. the aim of the study was to present the outcome of functioning tumors of the adrenal gland in children. methods. we reviewed medical records of children with adrenal tumors treated in our unit from to . demographic datas, clinical features, operative details, histopathological details and follow up were studied. results. there were children with the mean age . ae . years. two patients had virilizing tumors and presented with an acute abdomen, one patient had conn's syndrome, one patient cushing's syndrome and one patient presented with severe haemorrhagic shock syndrome. all patients were treated surgically. histopathological diagnosis were adrenocortical carcinoma (acc) in two patients, adrenocortical adenoma (aca) in two patient and adrenocortical cyst in one patient. ultrasound sonography, computerized tomography and magnet resonance imaging were used for diagnosis and follow up. patients with acc had advanced-stage disease and died despite total surgical resection and agressive chemotherapy. patients with aca and adrenocortical cyst were cured by surgical resection. conclusions. adrenal tumors constitue less than % of paediatric neoplasm. aca and adrenocortical cyst are cureable by surgical treatment, but the outcome is still poor in cases of acc. endoscopic subureteral injection of bulking agents has become an established alternative to long-term antibiotic prophylaxis and ureteral reimplantation. we evaluated the effectiveness of dextranomer=hyaluronic acid copolymer (deflux + ) and predicting factors for success or failure. a total of ureters= patients with a mean age of . years underwent endoscopic treatment with dextranomer= hyaluronic acid (dx=ha) copolymer. vur in duplex ureters was treated in patients. the presence of voiding dysfunction and renal scars, the volume of deflux injected and the endoscopic appearance of the ureter were recorded. dextranomer-hyaluronic-acid was injected submucosally beneath the intramural part of the ureter at o'clock, but if the appearance was not satisfying or the ureter opens during flow an additional injection at and o'clock was performed. all patients received antibiotic treatment till a voiding cystourethrography (vcug) was performed weeks after injection. ultrasound examination was performed after hours, months, months and one year. success was defined as no reflux on postoperative voiding cystourethrography. a total of ureters underwent to treatments. the overall success rate was %. the cure rate according to reflux grade was % for grade i, % for grade ii, % for grade iii. in vur grade iv and v the endoskopic treatment failed in most cases. there was no case of obstruction at up to month postoperatively. haemorrhage occurred in one patient. in five ureters an increase of vur grade developed. new contralateral vur was seen in six patients. in . % vur was found on postoperative vcug at years after endoscopic treatment. there was no statistic significant difference in volume injected when successes were compared with failures. among children with a small kidney the response rate was %. a positive response was observed in % of children with duplex ureters. the presence of voiding dysfunction had no influence on success. patients in whom endoscopic treatment failed underwent open surgery. the subureteral injection of dextranomer=hyaluronic acid is an effective and well tolerated alternative to open surgery or conservative treatment, also in patients with duplex ureters. in patients, who subsequently require reimplantation, the operative repair does not appear to be compromised. background. almost all patients with symptomatic vur were treated with a cohen procedure and a very high success rat. since we offer the endoscopic procedure with deflux. the outcome of the endoscopic treatment is evaluated. methods. between = and = , patients with refluxing units were treated (i ¼ , ii ¼ , iii ¼ , iv ¼ , v ¼ ). the control after treatment was between and months. additional urological diseases are: solitary kidney ( ), double kidney ( ), neurogenic bladder with mmc ( ), bladder trabeculation w=o neurological disease ( ), cloacal malformation ( ), bladder exstrophy ( ), urethral valve ( ) . age at treatment was between mths and yrs. injection was performed under general anesthesia, bolus was between . and . ml. three patients were additionally treated with botox. results. sixty patients need no further treatment after injection ( resolved and patients have reflux). in of patients, who need a second injection ( overactive bladder), reflux resolved as well as in patients after third injection. in patients with neurogenic bladder and mmc we had no success and further treatment (augmentation) was necessary. in patients reflux worsened and cohen operation was performed. in patients a vcug will performed in the near future and three are lost for control. conclusions. in cases of moderate reflux with no neurogenic bladder it is an excellent method to treat reflux. in cases of neurogenic bladder, we cannot recommend it and cases with bladder trabeculation need an additional medical treatment or operation with a higher success rate. all these patients need a long term follow-up. background. bariatric surgery in austria has a long tradition since , but has always been different to the international trends. in order to obtain an overview of growth and time trends of obesity surgery in austria a nationwide review has been done by the austrian national federation for surgery of obesity every two years since . methods. e-mail requests are sent to every department of surgery in public hospitals and clinics to collect the recent number of operations including revisional procedures. results. the last reviews (including ) showed a steady increase of obesity surgery particularly in the years through the number of operations increased %. since a constant number of interventions of about per year ( : ) had been observed. predominant operation techniques were restrictive procedures: - vbg (vertical banded gastroplasty) and since agb (adjustable gastric banding). since the late nineties austria is a gastric-banding country ( % in ) compared to the worldwide review data ( % in ), but since we observe a steep increase of gastric bypass paralleled by a decrease of agb. by the time of the conference data of the review starting in january will be presented a showing the trend of the last two years. conclusions. bariatric surgery as the only effective treatment against the alarmingly increasing disease of severe obesity is already an important part of the surgical work of some austrian surgical departments. in view of this fact quality control by continuous data collection is of major importance. restrictive bariatric procedures -long term results and complication management k. miller background. vertical banded gastroplasty (vbg) has been in clinical use since and the adjustable gastric band (agb) since . as promising results were achieved with the adjustable gastric bands available in the market, some surgeons came to the conclusion that vbg might be entirely abandoned and replaced by the adjustable gastric band. the aim of this study was to compare the long term outcome of the two different restrictive procedures. methods. within a period of years ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) , gastric restrictive procedures were performed in the course of a prospective non-randomized comparative trial. we report the outcomes of vbgs and agbs performed by two surgeons. the mean bmi was . ae . for vbg and . ae . for agb. patient selection was performed by admittance to one of the two surgeons. vbg was performed via laparotomy and agb by the laparoscopic procedure. the bariatric analysis and reporting outcome system (baros) was used to evaluate the postoperative health status and quality of life. results. the mean duration of follow-up was months, with a minimum of years (range, - months). the overall follow-up rate was %. in the short-term follow-up of years, no statistically significant difference was registered between agb and vbg in terms of weight loss, reduction of co-morbidity or improvement of quality of life. the -day mortality rate was . % ( patients) for vbg and . % ( patient) for agb. the overall re-intervention rate in the long term was . % for vbg and . % for agb (p < . , or . , % ci . - . ), the re-operation rate . % for vbg and . % for agb (p < . ), respectively. the excess weight loss (ewl) was significantly higher in the vbg group after months ( % for vbg vs. % for agb; p < . ). in the long-term follow-up with a mean value of months, no significant weight loss was registered between the study groups ( % for vbg and % for agb; p ¼ . ). the baros score in the short term ( years) was good to excellent in and % of the vbg and agb groups, respectively. in longterm follow-up the baros score was significantly in favor of the agb group ( . vs. . %; p < . , or . , % ci . - . ). the overall loss of co morbidities was % in both groups. conclusions. this long-term follow-up study shows that vbg and agb are effective restrictive procedures to achieve weight loss, and loss of comorbidities. a statistically significant lower re-intervention and re-operation rate and an improved health status and quality of life were registered for agb. pilot study on the effects of gastric electrical stimulation (tantalus tm ) on glycemic control in morbidly obese patients with type diabetes (t dm) a. bohdjalian , b. ludvik , s. shakeri-manesch , r. weiner , c. rosak , g. prager background. previous work suggests that non-excitatory electrical stimulation, synchronized to the gastric refractory period and applied during meals, can induce weight loss in morbidly obese subjects. the tantalus tm system (metacure n.v.) is a minimally invasive implantable gastric stimulation modality that does not exhibit malabsorptive or restrictive characteristics. aim: to investigate the potential effect of the tantalus tm system on glycemic control and weight in morbidly obese subjects with t dm. methods. in this european multi-center, open label study, t dm obese ( m, f, bmi: . ae . kg=m ) subjects treated either with insulin ( ) or oral anti-diabetic medications ( ) were implanted laparoscopically with the tantalus tm system. the system includes a pulse generator and three bipolar leads and delivers a non-excitatory signal initiated upon automatic detection of food intake. results. twenty subjects have completed one year and exhibit a decrease in hba c from ae . % at baseline to . ae . % (p ¼ . ) and in fasting blood glucose from ae mg=dl to ae mg=dl (p< . ). sixteen subjects on oral anti-diabetic medications showed a decrease in hba c from . ae . % at baseline to . ae . % (p< . ) and an average weight loss of . ae kg (p< . ), self glucose monitoring available at months post-op from subjects shows a significant (p< . ) decrease in hours post-prandial glucose ( ae mg=dl vs. ae mg=dl). in a subset of patients at months of post-operative follow-up we could find an increase in adiponectin ( . ae . vs. . ae . mg=ml, p < . ) and a decrease in fasting ghrelin ( ae vs. ae pg=ml, p < . ). the areas under the curve (auc) measured during meal tolerance test were significantly higher for adiponectin and lower for ghrelin (p < . ) compared to pre-therapy. four insulin subjects have completed one year and showed no significant changes in hba c and weight. conclusions. interim results with the tantalus tm system suggest that this stimulation regime can potentially improve glucose levels and induce weight loss in obese t dm subjects on oral anti-diabetic therapy. further evaluation is required to determine whether this effect is due to induced weight loss and=or due to direct signal dependent mechanisms. background. gastric sleeve resection was initially devised as the first step of the duodenal switch operation in bariatric surgery. later, it was performed as an isolated restrictive procedure, mostly laparoscopically. we present intermediate to long-term results from a large series of laparoscopic sleeve resections (lsg) in three austrian centers. methods. ninety-eight patients ( males, females) who all met the ifso criteria for bariatric surgery were included in this study. the mean bmi was . kg=m (range, - kg=m ). patients with symptoms of gastro-esophageal reflux or large hiatal hernias as well as ''sweet eaters'' were excluded and allocated for a different procedure (usually roux-en-y gastric bypass). ninety-five of the operations were performed laparoscopically: after establishing a pneumoperitoneum of mmhg, four to five working trocars were introduced. beginning opposite the crow's foot, the greater curvature was dissected from the omentum up to the angle of his. the left crus of the diaphragm was always identified to ensure complete resection of the gastric fundus. the stomach was then reduced to a tube over a f gastric bougie with several magazines of an endostapler, the staple line was finally oversewn with a continuous - pds suture. three patients had sleeve resection via an open access. results. after a median follow-up of months, patients had lost . kg=m of their bmi or % of their excessive weight on the average. there were six failures of lsg: three patients had gained weight despite lsg and three patients had lost less than % of their ew within one year. three of these patients underwent gastric bypass operations that were successfully performed laparoscopically. major complications included leaking of the staple line necessitating reoperation (three patients), severe wound infection (two cases, one of them after conventional sg), minor wound infections (three cases), and postoperative gastro-esophegeal reflux (one case), resulting in an overall complication rate of . % for severe and . % for minor complications. there was no operative mortality. conclusions. laparoscopic gastric sleeve resection is an effective and safe procedure with encouraging intermediate results. there is no implantation of foreign material, the procedure is less invasive than malabsorptive techniques. in the case of failure, it can readily be converted to gastric bypass or duodenal switch (with or without biliopancreatic diversion). on the other hand, this method has yet to stand the test of time within the spectrum of bariatric surgical procedures. background. bariatric surgery is indicated in patients with a bmi exceeding and presenting comorbidities or bmi ! . lgb is accepted as one of most successful surgical procedures to treat obesity. aim of study: a prospective analysis of the first patients who had been treated with lgb in our centre. methods. according to our treatment protocol at least dietetic attempts have to be failed to enrol the patient in the surgical program. lgb is performed in patients with a bmi ! with comorbidities or a bmi ! when gastric banding is unlikely to succeed. thirty patients (f:m ¼ : ) with a mean age of ( - ), mean bmi . (sd . %) underwent an antecolic, laparoscopic gastric bypass, performing the gastro-enteric as well as the entero-enteric anastomosis with linear stapler, closure of the enterotomies with manual continuous suture with pds, closure of the mesenteric defect with a non absorbable running suture. the postoperative controls had been performed on month ., ., ., . and . calculating the corresponding bmi. results. perioperative morbidity: two reoperations due to intestinal obstruction, two intraluminal bleeding of the anastomotic suture line, one case treated endosopically, one conservatively, no mortality was observed. the ewl months after performance of lgb was calculated to be % (sd %). conclusions. this series document that acceptable results may be achieved even during the learning curve of laparoscopic gastric bypass. background. in up to twenty five percent of morbidly obese patients restrictive procedures as vertical banded gastroplasty (vbg) or adjustable gastric banding (lagb) do not lead to adequate weight losses. transformation to a gastric bypass represents a therapeutic option in these patients. methods. from to revisional gastric bypass was performed in patients ( after vbg, after lagb, and after sleeve gastrectomy). the main indication for redo surgery was inadequate weight reduction. results. four ( %) surgical complications (incarcerated trocar hernia, intra-abdominal abscess, subphrenic abscess, leakage gastro-jejunostomy) occurred and had to be treated by a reoperation. one patient died of septic shock caused by a subphrenic abscess resulting in gastro-jejunal leakage and peritonitis (mortality rate: %). on follow-up patients after complications lost equal amounts of excess weight compared to uncomplicated cases. conclusions. revisional gastric bypass is a safe and potentially effective option for patients with inadequate weight loss after restrictive surgery. however, postoperative morbidity and mortality rates are higher compared to primary operations. operational cost accounting reflects in an impressive manner the medically already evident advantages for our patients. a laparoscopically performed colon resection with fast tracking costs e . , including pre-and post-surgical hospitalization. the same procedure without fast tracking results in costs of e . , . open colon resection including fast tracking adds up to e . , . conventional procedure without fast tracking even amounts to e . , . furthermore combining the operational results with the economical calculation results in a cost cutting potential of an extra e , per person, who has undergone laparoscopic surgery and was treated with fast tracking. in conclusion it can be stated, that this strategy of treatment means not only a severe post-surgical improvement of quality of life but in addition also shows significant economical advantages. the best method of treatment from both the medical but also the economical point of view is therefore the combination of laparoscopic colon surgery with fast tracking. is the laparoscopic sigmoid resection with a primary anastomosis in acute sigmoid diverticulitis the optimal surgical therapy? background. the late elective laparoscopic sigmoid resection for diverticulitis has become an acceptable therapy for diverticulitis, but the optimal surgical procedure of the acute diverticulitis has not been established. the optimal waiting period after acute symptoms of diverticular disease is still discussed controversial. the resection and primary anastomosis in acute diverticulitis may advance the challenging process for this surgical approach. methods. from may to january a laparoscopic sigmoid resection was performed in patients (male: , female: ) with a sigmoid diverticulitis. the average age was years for the males and years for the females. = patients were operated early elective within days after acute signs of diverticular disease (according to hansen and stock grade iia and iib) by a single surgeon, and = patients late elective by different surgeons. from all patients the clinical course, the operative time, the length of the sigmoid resection, the post-operative hospitalization and the complication rate were evaluated. results. according to the asa-classification = patients were graded as asa i, = as asa ii and = as asa iii. patients were divided in three groups. group i ( = ): early elective operations, group ii ( = ): late elective operations but with intraoperatively signs of an acute diverticulitis and group iii ( = ): late elective operations without manifestations of an acute process. the average operative time in minutes was in group i: (range - ), group ii: (range - ) and group iii: (range - ). the length of the resection specimen was comparable in group i and iii with an average length of mm, in group ii mm. the average extent of hospitalization was in group i: . days, group ii: . days and group iii: . days. none of the patients had conversion to laparotomy. complications were: group i one wound seroma, group ii one ureteral injury, one incision hernia and group iii three wound infections, one anastomotic leak and one incision hernia. since the localization and operative technique of the wound suturing was varied, an incision hernia was not observed. conclusions. the advantage of the early elective sigmoid resection after acute sigmoid diverticulitis is a short one-stage hospitalization with a low complication rate. in experienced centers the laparoscopic early-elective sigmoid colectomy seems to be a feasible and optimal surgical procedure for the acute sigmoid diverticulitis. laparoscopic resections for colorectal diseases: indications, operations, results s. riss, c. bittermann, p. dubsky, f. herbst background. laparoscopic assisted surgery for colorectal diseases has potential advantages over the traditional open technique. several studies reported that the laparoscopic approach offers multiple benefits such as faster recovery, better cosmesis, a lower incidence of adhesion-related complications and incisional hernias. the current study was designed to assess the role and feasibility of laparoscopic procedure in colorectal surgery. methods. from to patients ( females, males) underwent laparoscopic colorectal resections. mean age was (range - years) with a mean body mass index of . kg=m (range . - . kg=m ). indications included benign (inflammatory bowel diseases, diverticulitis, slow transit constipation, colon adenoma, fap) and malignant conditions with curative and palliative intent. all operations were performed or directly supervised by one single surgeon. intraand postoperative parameters were documented and statistically analysed retrospectively. results. over a year period operations in patients were performed, including bowel resections ( malignant) and anastomoses. average duration of operation was min (range - ). the mean time of hospital stay was days (range - ). the total conversion rate was . %. postoperative complications were observed in patients: surgical complications occurred in cases, with patients requiring reoperation (bowel obstruction n ¼ , anastomotic leak n ¼ , trocar hernia n ¼ , anastomotic bleeding n ¼ ). thirteen patients developed medical complications after operation and were treated conservatively. one patient ( . %) died due to cardiorespiratory failure. conclusions. the present study included a wide range of indication criteria. notable, despite a high number of patients with inflammatory bowel diseases, there was a low rate of surgical complications. thus the minimal invasive approach seems to be safe and effective for a broad spectrum of colorectal diseases. rectal carcinoma in the era of ''minimal invasive''-and ''fast track''-surgery p. razek, c. kienbacher, a. tuchmann background. laparoscopic surgery for colon cancer is feasible and effective with good results in regard of postoperative recovery. fast track protocols are changing perioperative treatments to the same aim. at the time there are no randomized studies available to compare the effect of laparoscopy and fast tract strategies to an open and conventional procedure for rectal carcinoma, which is still surgical standard. methods. from to patients were operated laparoscopically for rectal cancer ( males and females; mean age a, a- a). patients staged t were excluded. excessive preoperative surgery (i.e. right hemicolectomy, sigmoid resection, prostate resection), severe cardiac and pulmonary diseases or a high bmi did not effect the indication for laparoscopy. patients, ( %) staged t preoperatively, received chemotherapy and long time radiation. in the first period (-ii= ) patients were treated according to a conservative perioperative management. thereafter ( ) ( ) ( ) a fast track protocol was applied to the following patients. results. abdominoperineal extirpations (n ¼ ), anterior resections in double stapler technique (n ¼ ) and coloanal anstomosis (n ¼ ) were performed. conversion to open surgery was necessary in two cases ( . %), [bulky disease and a narrow male pelvis (n ¼ ), anatomical reasons (n ¼ )]. operation time was long and varied from to minutes (mean minutes). r was achieved in % ( patients with metastatic disease were staged r , one patient with a colonic wall lesion and potential spillage). postoperative stay for the laparoscopic group was days, for the combined laparoscopic þ fast track group was days (in comparison with days for conventional and open surgery). complications, mortality and side effects were reported. conclusions. exceptional view inside a narrow pelvis by the means of laparoscopy creates good conditions for total mesorectal excision and nerve sparing technique. minimal invasive surgery reduces the surgical trauma as a basis for an early postoperative recovery. the combination with a fast track protocol furthermore helps to establish even better results. the importance of laparoscopy in the management of postoperative complications c. kienbacher, p. razek, p. patri, a. tuchmann background. postoperative complications, especially anastomotic leakage after laparoscopic colon surgery are a hazard for all surgeons. most important is to recognize the early signs of complications such as abdominal pain, fever, chill, persisting nausea and vomiting and increasing abdominal swelling. the erlier a reintervention is done the better is the outcome for the patient. requesting a single and sufficient procedure, most surgeons don't even think about a minimal invasive reintervention. from = until = patients underwent laparoscopic colon surgery, patients had to be reoperated. twenty-five patients had a relaparoscopy, only two times we converted to the open procedure. patients had to underwent primarily open abdominal surgery, patients had abdominal wall problems and did not need an intraabdominal procedure. methods. concerning the intraabdomial complications we performed laparoscopic washouts, patients had a laparoscopic incisional hernia repair, patients bleeded from the trocarincisions, a laparoscopic anastomosis resection was performed, patients got a laparoscopic ileostomie, times it was necessary to perform a laparoscopic bowel diversion and times the hartmann procedure was performed minimal invasive. results. the traditional open reinvention was required in patients, all showed a peritonitis and a colon diversion with stomatherapie was done. eighteen patients had a single reintervention. after laparoscopic redos the median postoperative stay was far shorter than after open procedure. patients died. conclusions. laparoscopic reinterventions are feasable in most cases, the advantages are less postoperative pain, shorter hospital stay, quicker return of bowel fuction and improved cosmetic results. compensatory sweating after endoscopic sympathetic block at t background. endoscopic thoracic sympathectomy is the treatment of choice for patients with primary hyperhidrosis (hh). compensatory sweating (cs) is the most frequent unwanted side-effect of this surgical procedure. recently, clip application (endoscopic sympathetic block, esb) has been introduced as it provides reversibility. furthermore, sympathetic block solely at the level of the th thoracic ganglion (t ) was proposed to reduce cs and still effectively cure palmar hh. the aim of the study was to analyze the outcome of patients treated by esb at the level t with special reference to cs. methods. between and patients (mean age . ae . years) prospectively underwent procedures (one unilateral and bilateral operations). satisfaction rates and quality of life scores have been evaluated. mean follow up was . ae . months obtainable from patients ( . %). results. one hundred and three patients ( . %) had palmar, ( . %) axillary and ( . %) combined hh. at follow-up, all patients with palmar and . % with axillary hh were completely or nearly dry. cs was observed in ( . %) patients. most frequently, the back ( . %), the thighs ( . %), the abdomen ( . %), the feet ( . %) and breasts ( . %) were affected. in . % one single body region was affected, in . % two and in . % three regions became humid. cs significantly diminished quality of life (p < . for both questionnaires). consequently, . % were unsatisfied with the final outcome. however, the vast majority of patients were completely or almost completely satisfied. conclusions. esb at t gives excellent results for palmar and good results for axillary hh. however, cs primarily affecting the back and the thighs diminishes patients' quality of life and satisfaction. right donor nephrectomy, a major challenge is adequate renal vein length, due to vascular anatomy. methods. all patients undergoing laparoscopic donor uretero-nephrectomy between and were included. side of nephrectomy was selected based on selective renal function assessment and vascular anatomy. standard laparoscopic access was gained through trockars, the kidney dissected from its capsule, the vessels isolated, and the ureter transsected. following transsection of the renal artery (proximal closure with clips to maximize retrieved vessel length), and the renal vein (proximal closure with vascular stapler), the organ was procured through a mini-laparotomy connecting two trokars. in laparoscopic assisted right nephrectomy, the vein was retrieved with a vena cava patch using a semi-open approach: following isolation of the vascular structures and ureteral transsection, the confluens of the renal vein with the inferior vena cave was excluded using a curved clamp through a mini-laparotomy in the right upper quadrant. the caval patch was created by cutting the vein closely distal to the clamp, with reconstruction of the vena cava by a running blalock suture. patients undergoing laparoscopic assisted right resection (study group sg) were compared to patients with laparoscopic left nephrectomy (control group cg). data are reported as mean ae standard deviation or total numbers (% . total morbidity was ( . %), including ( . %) infections, and ( . %) postoperative lymphatic leaks. two ( . %) major complications (bleeding ( ) and intraabdominal abscess ( )) resulted in reoperation (sg vs. cg ; p ¼ . ). conclusion. the laparoscopic assisted approach to right kidney procurement is feasible, allows for sufficient length of the right renal vein for transplantation, and donor morbidity is comparable to laparoscopic left nephrectomy. clinical implementation of radius surgical system in mis w. feil, i. pona, t. filipitsch, p. jiru, u. satzinger limited mobility of instruments and absence of depth perception are significant issues in advanced laparoscopy. by that procedures including complex suturing and anastomoses in narrow operating fields in difficult angles of visualisation exceptionally challenge experienced surgeons. the radius surgical system (tübingen scientific medical gmbh, tübingen, germany) consists of manipulators for mis (right and left hand) suitable for mm trocars allowing a freedom of movement comparable to robotic devices. the instrument tip can be deflected by by handle deflection and rotated via handle knob. compressing and releasing of the instrument jaws works conventionally. radius system was implemented in the ekh vienna by = . in advance a -day training course was absolved by the surgical team. radius system was used for a series (n ¼ ; = ) of reflux operations to perform hiatal suturing and fundoplication. in practice handling of radius taking advantage of all features turned out so physically mandatory, that a training course is unanimously recommended even for surgeons with experience in all mis suturing techniques. in pratice the needle could be guided with significantly higher precision if compared to convention needle-holders. even suturing in narrow cavities and in difficult angles became feasible (video). after full accomodation to radius the next step of implementation is the creation of handsewn anastomoses, esp. in bariatric surgery. precision, reliability, safety and tightness of sutures and sewn anastomoses are crucial for the outcome quality of advanced mis procedures. for that the radius surgical system has shown to be extremely beneficial. does lifting of the abdominal wall for the set up of the pneumoperitoneum for laparoscopy increase the safetiness? a. shamiyeh , j. zehetner , h. kratochwill , k. hörmandinger , f. fellner , w. u. wayand background. to evaluate the intraabdominal changes while lifting the fascia with regard to the distance between the fascia and the retroperitoneal vessels and the intestine for access in laparoscopy. fifty percent of all complications during laparoscopic procedures occur during the establishment of the pneumoperitoneum. the blind insertion of the veress needle is the most popular way of access. elevation of the abdominal wall or the fascia is recommended, though the benefit has not been proven yet. methods. for patients scheduled for laparoscopic cholecystectomy the operation started in the ct scan. after orotracheal intubation a ct scan was performed of the umbilical region with cm proximal and distal margin. after a supraumbilical incision the fascia was freed and elevated with stay sutures. during maximal elevation, a second ct scan was performed. the distance between the fascia and the intestinal structures (small bowel) and the retroperitoneal vessels (iliac artery, aorta, vena cava) was measured after both scans and the difference was evaluated. results. lifting of the fascia increased the distance between the fascia and the intestinal structures with a mean of . cm (range . - . cm), the distance between the fascia and the retroperitoneal vessels with a mean of . cm (range - cm). conclusions. elevation of the fascia at the umbilical region prior to the first entering into the abdominal cavity for laparoscopy does increase the safeties due to enlargement of the distance between the fascia and the intraabdominal and retroperitoneal structures. background. despite many years of experience in breast reconstruction even as an immediate one stage procedure, there are still rumours about this technique, even among oncologic surgeons. these are concerning the influence on the oncological outcome, radio-and chemotherapy, severity of the operation, possible complications and patient's satisfaction. the presentation offers answers to most of these rumours from our own experience and the recent literature. methods. one hundred and eighty breast reconstructions were performed between and in our department, as immediate and as delayed procedures. eighty-seven were done with microsurgical autologous flaps and with a latissimus dorsi flap, in the rest various techniques like prostheses and expanders were applied. patient data were collected concerning early and late complications, oncological outcome, influence on radio-and chemotherapy and patient's satisfaction. results. reconstructions with prostheses required shorter operating times, but mostly late revisions were more frequently, especially in combination with radiotherapy. among the group of patients, in whom flaps were applied, only one was lost. with increasing experience, the need for blood transfusions, the postoperative morbidity and the length of the hospital stay decreased. in no case radio-or chemotherapy had to be delayed due to immediate breast reconstruction. secondary axillary lymph node dissection due to a positive sentinel node was possible even after a flap which was pedicled in the axillary vessels. our experience is well reflecting the results of the recent literature. conclusions. despite many existing rumours breast reconstruction, even as an immediate single stage procedure, can be regarded as an operation which does not inflict the oncological therapy. to optimise the results, however, indications must be set very carefully. background. positron emission tomography with the glucose analog [ f]-fluorodeoxyglucose (fdg-pet) has been used for response evaluation in patients with esophageal squamous cell carcinoma (escc) during neoadjuvant radiochemotherapy (rtx=ctx). this prospective study was undertaken to compare fdg-pet assessment of tumor response during rtx=ctx with histopathology in patients with escc, and to correlate the findings with survival. methods. sixty-one patients with histologically proven escc (ct , cn =þ, cm ) underwent preoperative, simultaneous rtx=ctx followed by esophagectomy between and . the patients underwent fdg-pet prior to and weeks after the begin of rtx=ctx ( gray). histopathological response was quantified as the percentage of residual tumor cells. the threshold pre-therapy-to-during-therapy decrease in standardized uptake value by fdg-pet used to define metabolic responders (Ásuv r ) was À %. results. receiving-operator-curve analysis (roc) for determination of metabolic response revealed an area-under-curve (auc) of (p ¼ . ) with a sensitivity of %, specificity ( %), a positive predictive value of % and a negative predictive value of % (p < . ). responder by fdg-pet during the neoadjuvant treatment (p ¼ . ) as well as histopathology (p < . ) showed substantially better survival compared to nonresponders. conclusions. changes in tumor metabolic activity by fdg-pet during neoadjuvant rtx=ctx allows an accurate determination of response due to the multimodal approach in patients with escc. this stratification may lead to a change of the neoadjuvant into a definitive therapy concept in nonresponders (individualized tumor therapy). background. totally endoscopic coronary artery bypass grafting (tecab) requires telemanipulation technologies because attempts using conventional thoracoscopic instrumentation have completely failed. these complex operations take individual and team learning curves and a stepwise approach is necessary. methods. from to cabg procedures were performed using the davinci tm system. a low risk patient population (age ( - ) years, euroscore ( - )) was treated. the following procedures were carried out: endoscopic ima takedown in midcab, opcab, and cabg (n ¼ ), robotic suturing of lima to lad anastomoses through sternotomy (n ¼ ), single vessel tecab (n ¼ ), double vessel tecab (n ¼ ). results. the number of totally endoscopic approaches through ports only increased from % in to % in . there was no hospital mortality and cumulative risk adjusted mortality (cram) plots showed that . predicted events did not occur. given event free procedures clopper pearson estimations revealed a % confidence interval between . % and . % for perioperative mortality. cumulative year survival was %, and year freedom from angina was %. conclusions. introduction of robotic totally endoscopic coronary artery bypass grafting seems to meet current cabg safety standards. initial application in low risk patients and a stepwise approach to completely endoscopic versions of the operation seem worthwhile. using this way single and double vessel tecab can be performed. intermediate term survival and revascularization results appear to be very satisfactory. icu stay was a mean of day in both groups and hospital stay lasted on average . ae . days in the bh group and . ae . days in the ah group (p ¼ . ). the advantages of arrested heart tecab are various -more space through the relaxed heart, -superior anastomosis quality through the arrested heart, -no manipulation of the lad with tapes and a clear operating field through the use of crystalloid cardioplegia, -no occlusion of the lad with the risk of ischemia, and result in shorter anastomosis as well as operating times and do not increase icu and hospital stay. methods. initially an experienced gi-surgeon was trained in an experimental centre in the application in both, open and laparoscopic application of the flexible shaft stapling system. after experimental sessions the system was used in clinical open surgery in cases before the laparoscopic approach was used. for laparoscopic procedures a stepwise learning curve was applied (from laparoscopic appendectomy, colon resection to laparoscopic gastric resection and esophageal resection). for intraabdominal application of the linear stapling device a mm trocar and for the circular stapling device a mm trocar was used. technical problems, operation time and operative complications were prospectively documented. results. the flexible stapling device was used in patients ( conventional, laparoscopic surgery). a mean of stapling procedures (range - ) was performed per patient. during the early phase technical problems were observed in patients ( formation of gastric tube for esophageal reconstruction, three formations of colonic anastomoses). all problems were solved by repetition of the anastomoses. nine leakages ( . %) were observed: two after esophageal surgery ( = ; . %), one after gastric surgery ( = ; . %) and six after colon surgery ( = ; . %). conclusions. the flexible shaft stapling device is safe in open and laparoscopic surgery. technical problems in the early phase were not due to malfunction of the device. the problems and complications are within the limits of conventional stapling. since there is a learning curve for handling, proper training in laparoscopic and open surgery is advised. the new flexible stapling device showed beneficial in special indications in laparoscopic surgery. the handling of the device is possible in any location in the abdomen, which makes procedures like collis-plasty feasible to be performed laparoscopically. circular stapled anastomoses of the colon above the rectosigmoid junction can easily be performed in circular stapling technique. background. intra-und extraplexuale nerventransfers kommen routinemäßig in der rekonstruktion posttraumatischer plexus brachialis läsionen zur anwendung. in den letzten jahren wurden einige neue selektive distale nerventransfers beschrieben, welche ein geringes defizit an spendernerven hervorrufen, möglichst nur motorische fasern beinhalten und ein hohes maß an funktioneller synergie besitzen. in der vorliegenden retrospektiven arbeit werden die operativen details, und langzeitergebnisse von patienten bei welchen diese techniken zur anwendung kamen vorgestellt und analysiert. methodik background. long lasting brachial plexus lesions (bpl) require free functional muscle transplantation to restore some distinct motor function. methods. five patients, receiving a total number of free vascularized muscle transplants are presented. all patients were male, aging , , , and years. patients suffered from obstetrical, from traumatic bpl. unstable shoulder (n ¼ ) and lacking biceps function (n ¼ ) were the indications for surgery. the gracilis muscle was used in cases to replace deltoid (n ¼ ) and biceps (n ¼ ). in one case a rectus femoris muscle was transferred into deltoid position. reinnervation of the muscle transplants at the shoulder was perfomed end-to-side to the spinal accessory nerve. in biceps position the motor nerves of the gracilis were coaptated end-to-end with the ulnar nerve (oberlin procedure, n ¼ ) or intercostal nerves (n ¼ ). results. surgery was successful in all cases primarily. all transplants showed reinnnervation starting months after surgery. stabilisation of the shoulder was achieved in all cases, furthermore of these cases regained active shoulder abduction= flexion up to degree. gracilis in biceps position reached m , are reinnervating. conclusions. free vascularized muscle transplantation seems to represent an useful tool for reconstruction of some distinct, essential motor function in paretic limbs due to bpl. background. since viterbo presented his exquisite results from terminolateral coaptation in small animals a new source for neurotisation seemed to be provided. viterbos results and our own good experience with free functional muscle transplantation encouraged us to use the technique in brachial plexus surgery. in a retrospective analysis we wanted to prove whether or not terminolateral neurorrhaphy produces functional results in brachial plexus surgery. methods. in patients, suffering from minimum c , avulsion and=or rupture a total of terminolateral procedures was carried out: times the suprascapular nerve was connected with the spinal accessory nerve and times the biceps motor nerve with the ulnar nerve, after creation of an epineureal window in all cases. results. patients were investigated . (ae ) month after surgery. the modified oberlin procedures (n ¼ ) showed m . the ss to xi procedures ranged from m (n ¼ ) to m (n ¼ ). multichannel emg evaluation did not reveal isolated function of the reinnervated muscles but action in parallel with the ''source muscles''. in out of procedures the terminolateral neurorrhaphy was sufficient to regain useful muscle function, i.e. to stabilise the shoulder and to add some minimal active function. conclusions. with respect to the severity of the lesions one might consider this an acceptable result. actually we did expect better results from the procedures, as we did achieve m and m function with free functional muscle transplantation and terminolateral neurorrhaphy in children. regarding our experience, the technique represents an useful tool for reinnervation, provided an unimpaired function of the donor nerve. current concept for treatment of obstetrical brachial plexus lesions w. girsch background. for a long time the treatment of obstetrical brachial plexus lesions (obpl) consisted of conservative treatment mainly. surgery was indicated only in severe cases suffering from persistant complete flail arm. gilbert introduced a much more aggressive concept with surgical intervention whenever the biceps is not working at three months of life, a strategy which caused discussions permanently. as a result of this discussion and with respect to clarkes work the concept was modified in the last years again. methods. the diagnosis of an obpl has to be followed by monthly clinical examinations. testing for muscle regeneration is not only focussed on biceps muscle but also on time and topographic course of regeneration. lack of shoulder and biceps activity at three months of life or negative ''handkerchief-test'' at six months represent indications for immediate surgical revision of the brachial plexus (primary early nerve surgery). in cases showing ongoing regeneration the conservative treatment is maintained. relevant deficiencies in motor function (less than % of rom or power in correlation with the unaffected side) at twelfe months of life represent an indication for brachial plexus surgery again (primary late nerve surgery). further nerve procedures, usually isolated nerve transfers (secondary late nerve surgery), can be performed in selected cases up to two years of life. after that time musle transfers and osteotomies (secondary procedures) are perfomed to achieve further increase in function. results. in brachial plexus surgery new concepts of ''extraplexual neurotisation'' and ''end-to-side neurorraphy'' have increased the possibilities of reconstruction by increasing the amount of nerve sources. secondary procedures, including free functional muscle transplantation, have become an integrative part of the overall treatment strategy. conclusions. although obstetrical techniques have improved in the industrialized countries, there still exists an incidience of - obpl per newborns, last but not least with regard to an increasing number of babies weighing more than g. it is known that of obpl recover spontaneously. new investigations have revealed relevant deficiencies in out of of these children at an age of years. actually the number of children requiring surgery is small. but for these children it is important to make the right decisions in time to minimise deficiencies and achieve optimal results. external derotation osteotomy of the humerus in patients with erb's palsy -effects on upper extremity kinematics b. gradl, m. mickel, m. schmidt, g. weigel, a. kranzl, w. girsch orthopädisches spital speising, kinderabteilung, wien, austria background. patients with untreated upper brachial plexus lesions frequently develop an internal rotation contracture of the shoulder, deficient active shoulder abduction and especially external rotation. the humeral derotation osteotomy combined with muscle transfers is one of the most common secondary reconstructive procedures to correct this deformity and improve the upper limbs function. the aim of this study was to investigate the patients' benefit of the surgical intervention. in order to objectively assess the functional outcome an optoelectronic motion analysis system was used to capture and analyze the kinematics of the involved limbs pre-and postoperatively. methods. eight children with secondary deformities following an obstetrical erb palsy were investigated before and after humeral derotation and muscle transfers. the patients' movements were captured by tracking the reflective markers which were applied to the upper limb and the trunk. the motion analysis was finished on the pc, resulting in various kinematic parameters, such as joint angles, motion curves, velocity and acceleration. static data was calculated to measure the amount of the shoulder malposition. results. results of the motion analysis document a dynamic as well as a static improvement of the involved limb in all eight patients. the average effective external derotation of the upper arm was , which means a correction to a nearly physiologic rotational positioning. active abduction increased in of patients with enhancement between and . active shoulder rotation improved in all patients ($ ). the maximum active elbow flexion did not increase, but the motion curves describing the movement changed: the velocity increased ( %), the compensatory shoulder abduction, which was observed during elbow flexion preoperatively in all patients, was reduced to a physiologic extent (compared to healthy probands). conclusions. derotation of the humerus as a secondary procedure allows functional improvement in patients with erb's palsy. this can be assessed by using a d motion analysis system. following global or lower brachial plexus lesions with intact biceps function in combination with missing radial nerve and weak median nerve function a supination contracture of the forearm is resulting. the supinated position of the forearm is functionally useless and often causes neglect of the extremity. five patients underwent surgical correction of this deformity, females (aging , and years) and males (aging and years). the biceps tendon was rerouted to the outside of the radius in cases and to the medial side of the ulna in one case. additionally correction osteotomies of radius and ulna had to be performed in the y old patient. reconstruction of extensor function was done in classical manner by tendon transfers. the tendon transfers did not only reanimate the extensors of carpus and hand but also augmented the light pronation of the forearm. all patients regained normal biceps and some simple hand function. regarding this, all patients started to use the extremity during adl for some, mostly bimanual tasks. correction of the supination contracture was highly beneficial for the patients. the procedure changed a useless extremity into a functioning part of the body. background. reconstruction of the distal weight-bearing area of the foot is surgical challenge, especially in diabetic patients. skin grafts do not provide adequate and permanent coverage of a weight-bearing region. local surgical options to cover these distal skin defects include forefoot amputation, a toe fillet flap and a reverse medial plantar island flap. the reverse medial plantar island flap is based on a very thin and possibly damaged intermetacarpal network. conventional angiography often is not a helpful tool for preoperative assessment, because foot vessels often remain occult. methods. the purpose of this study was to evaluate the viability of the distally based medial plantar flap in cadavers. angiographic imaging was possible in only cadavers reflecting the clinical preoperative assessment. distally based medial plantar flap dissection was done in all cadavers, as well as vascular dissection of the superficial and deep plantar arch. results. we found a well developed deep plantar arch in all cases. the deep plantar artery formed the main feeder of the deep plantar arch in %, while the second proximal perforating artery contributed to the deep plantar arch in %. the superficial plantar arch usually appeared slender and incompletely. conclusions. the distally based medial plantar flap could be dissected in all cadavers, whereas the quality of vessels was varying explicitly. the results of dissection always showed a constant vascular supply, but varying quality of supply. no clinical conclusions can be drawn, considering the slender vas-cular supply of the distally based medial plantar flap. optimized diagnostic angiographic procedures like mra or biplane selective dsa are essential for preoperative assessment planning distally based medial plantar flap. limberflap -salvage procedure for the non healing pilonidalis sinus t. kapp, h. marlovits, j. beck, f. hetzer kantonsspital st. gallen, switzerland background. surgical treatment of pilonidal sinus disease has a significant morbidity and recurrence rate. the rhomboid flap of limberg is a transposition flap that has been advocated for treatment of this condition. we present the technique and our experience. methods. in a prospective study starting in january we analysed consecutive patients ( females), median age years (range - years), with recurrent pilonidal sinus disease. we performed a complete rhomboid excision and closed the lesion by an excentric transposition flap designed to obliterate the middle cleft. morbidity was recorded and patient's satisfaction was analysed by a visual analog scale (vas). results. the median hospital stay was . days ( - days). we found in all patients a primary healing. minor complications were found in two patients. there was one flap oedema and one wound dehiscence, which were conservatively treated. no wound infection was observed. during the median followup of months ( - months) no recurrence occurred and high patient satisfaction was noticed. conclusions. although the limberg flap results in a slight asymmetric gluteal region patient's acceptance is high. fast healing, low complication and recurrence rate are the important advantages for this procedure. treatment of human painful neuromas and complex regional pain syndromes (crps) by co laser welding and regional subcutaneous venous sympathectomy (rsvs) -a new surgical approach w. happak, l. kriechbaumer background. since nearly years the treatment of painful neuromas is an unsolved problem. up to techniques are described with a recurrency rate of the pain between and %. the intramuscular transposition, the implantation into a vein and the end-to-side coaptation of the nerve stump are the state of the art operations. besides for years the treatment of complex regional pain syndromes type ii (crps ii) has been an unsolved problem. therapeutic approaches have included conventional pain medication, physical therapy, sympathetic blocks, transcutaneous or spinal cord stimulation, injections or infusion therapies and sympathectomy. alone or in combination these therapies often yielded unfavorable results. the majority of physicians, dealing with crps patients are convinced that surgical treatment only exacerbates the symptoms, and after the third neuroma pain-operation no improvement can be expected. after unsuccessful anaesthesiologic pain therapy over more than months, patients, with chronic neuroma or phantom pain were operated by co laser welding of the nerve stump in the last years. one third of the patients had or more pain operations. subsequently patients developed a crps type ii at the upper or the lower limb. the exact pain area was determined and the most proximal part where the crps commenced was infiltrated with % xylocain. when the sympathetic, deep, burning pain could be blocked, the subcutaneous veins in the previously determined area were removed surgically in a second step. a visual analogue scale (vas), the nottingham health score (nhs) and physical examinations were used to evaluate outcome of the operation. results. ninety-five percent of surgically treated painful neuromas and crps type ii patients showed significant improvement of limb function, the visual analogous scale (vas) and the nottingham health score (nhs). the medical pain therapy could considerably be reduced. conclusions. the presented data show that the superficial epicritical pain of neuromas can be treated successfully with co laser welding. the sympathetic, deep pain of the complex regional pain syndrome type ii can be treated successfully by a regional subcutaneous venous sympathectomy (rsvs). first clinical study of successful erbium-yag laser vaporisation of cutaneous neurofibromas l. kriechbaumer, w. happak background. with a prevalence of in births neurofibromatosis type i is one of the most common genetic defects. the mode of inheritance is autosomal dominant and affects a gene (nf ), which is responsible for the production of the tumor suppressor protein neurofibromin. the consequence is an uninhibited expansion of neural tissue which leads to cosmetic disfigurement of the patients. in comparison to the plexiform neurofibromas the cutaneous tumors do not undergo malignant transformation. excision and co laser vaporisation were established as standard treatment but cause unattractive scars. methods. in operations on two patients more than neurofibromas were removed with an erbium:yag laser. the tumors were dissected by shooting holes into the skin and vaporising the neurofibromas in-between or underneath. from test areas several biopsies were harvested for er:yag-, co and electrosurgical treatment in vitro to evaluate the difference of thermal necrosis histologically. photographs were taken to assess the cosmetic results. results. the fast healing by second intention as well as the minimal discomfort and scar formation following er:yag laser vaporisation was judged as excellent by patients and surgeons. we did not observe any hypertrophic scarring or lasting dyspigmentation. histologic evaluations revealed minor thermal damage to adjacent tissue resulting from this laser. conclusions. scars and changes in pigmentation resulting from excision or co laser-vaporisation often yield unfavourable results and the treatment is time consuming. er:yag laservaporisation of huge numbers of cutaneous neurofibromas is an uncomplicated and rapid procedure that achieves excellent cosmetic effects. background. lichen sclerosus usually presents a precancerous skin lesion of the genital region. skin grafting of penile defects is difficult because of the flexibility of the underlying recipient bed. this leads to disruption of the vascular ingrowth into the skin graft and compromises the results of the reconstruction. methods. we successfully used a circumferential vacuumassisted closure dressing with an incorporated urethral catheter to secure penile skin grafts in place during the early postoperative period. results. we achieved perfect take-rate of the graft and postulate good functional result concerning the stretched penile position during application of the vac-device. conclusions. a vacuum-assisted closure dressing can be used successfully to secure large and circumferential skin grafts, as well as skin grafts on concealed penises. background. there is a trend in reconstructive surgery towards modern techniques of defect coverage. such techniques are expected to combine high levels of safety, low donor-site morbidity, high aesthetic claims, short patient immobilisation and inpatient periods. the speculative applications for free, microvascular tissue transfers are expanded monthly while traditional reconstructive flap designs are no longer accepted as ''state of the art''. we present a case where modern defect coverage was not successful due to multiple comorbidities, localisation and complexity of the defect, and a step back to traditional flap designs was inevitable. methods. a previously healthy -year-old woman found a tumour on her back four years ago. diagnostic imaging and multiple biopsies revealed a cm-diameter chondrosarcoma with partial osteolysis of th = , tumour reaching into the spinal canal. she underwent radical resection and orthopaedic stabilisation from th -l , followed by chemotherapy and radiation of gy. one year after the operation metastatic lesions were found in both lungs. they were resected by video assisted thoracic surgery. due to resection of the erector trunci, the spine stabilisators loosened, two screws broke and the metal parts penetrated the skin. after local necrectomy, vac-therapy was performed for more than one year. severe headache and massive exsudation of the wound started in , suggesting dural leakage. a reversed latissimus dorsi-flap was performed, additional microanastomosis could not be done due to the very small calibre of the intercostal vessels. after one week, the metal-covering part of the flap showed muscle necrosis and had to be resected. a large fasciocutaneous transposition flap was designed and cautiously raised in steps of delay and could finally cover the defect. results. in this rare case of a chronic vertebral defect including spinal instability and liquorrhea reconstructive aims could not be reached by microsurgical techniques but by returning to traditional local flap designs. the patient is mobile and painfree, and there is no recurrence of liquorrhea since discharge. conclusions. technical advances and refinements in defect coverage are the basis for progress in reconstructive surgery. selected indications for traditional flap techniques still remain in modern reconstructive surgery dominated by microsurgical tissue transfer to cover problem defects. the missing link between tradition and innovation: skin tissue engineering l. kamolz, m. frey background. the need to achieve rapid wound closure in patients with massive burns and limited skin donor sites led to the investigation of in vitro cellular expansion of keratinocytes. the use of cultured epithelial grafts was first reported in the treatment of major burns. since , support for the use of keratinocytes has varied. the factors potentially limiting the use of cultured keratinocytes were cultivation time, reliability of 'take', vulnerability of grafts on the newly healed surface and long-term durability. the aim of this review is to evaluate the real impact of the clinical use of keratinocytes. one of the main aspects is to introduce new methods, which found or will find their way into clinical practice. methods. this study is mainly based on our long lasting experience in cultivating and transplanting cultivated keratinocytes (more than patients and sheets). results. the coverage of burn wounds with viable keratinocytes renders constant and reliable results. understanding keratinocyte-matrix interactions has not only allowed us to influence keratinocyte outgrowth, adhesion, and migration, but also has guided us to modify matrices for enhancing keratinocyte take. due to these improvements we have achieved a proper material in the adequate situation. conclusions. as surgeons, our goal is to help burn patients with the best quality of skin in the shortest time possible. as tissue engineers, we have not achieved the goal of a universal skin product yet, but by continually reviewing new options and using them, the anatomy and physiology of engineered skin substitutes will improve and they will become more similar to native skin autografts. thereby tissue-engineered skin may match the quality of split-skin autografts in future. background. the survival of patients with major burns goes hand in hand with early escharectomy and the survival of skin grafts. methods. the application of topical negative pressure has improved increased graft take especially in difficult anatomic regions. results. securing skin grafts in pediatric burn patients enabled a near % graft take. perfect protection from shear forces, early mobilisation, patient comfort, nursing comfort and abandonment of splinting are major advantages concerning conventional dressings. conclusions. we postulate the application of vac for securing skin grafts as a valuable tool in pediatric burns management. wide meshed grafts and including donor sites protected by silicon layers into the dressing in extensive burns should be evaluated carefully because of possible bleeding. background. versajet is a high -pressure hydrosurgery system, which enables a very precise surgical procedure. this single device technique combining lavage, excision, cleansing and aspiration allows a sharp debridement on any surface, or space. there are lot different indications for the use of versajet in plastic and reconstructive surgery. this system is appropriate for a variety of burn and traumatic wounds. because of the precise handling the use of this device is also in cosmetic surgery possible. methods. in this device a high velocity stream of sterile saline jets across the operating window and into an evacuation collector. because of a physical effect, a localised vacuum is created across the operating window. this holds and cuts targeted tissue while aspirating tissue from the site. therefore it enables to precisely target damaged tissue and spare viable tissue. surgical techniques can be enhanced, for instance the device holds targeted tissue during irrigation and excision. in addition, versajet cleans and cools at the same time as debriding, so additional cleaning techniques are not required. the depth of the skin -debridement is absolute predictable. in about cases the versajet has been used. the range of indications included burns, infected wounds (decubitus ulcers, traumatic wounds, fournier gangrene, necrotizing fasciitis). the advantage of this hydrosurgery system compared to sharp debridement using scalpels, dermatome, etc. is a more rapid and precise debridement, therefore the preservation of viable tissue, the precise and easy treatment of concavities and convexities and a reduction of blood loss could be achieved. histological findings proved the feasibility of an exact abrasion into different layers of the dermis. results. by using the versajet device, a reduction of the debridement procedures, an earlier reconstruction and a shorter time of hospitalisation could be achieved. the most important indication is the treatment of b burn-wounds. in burn cases the necrosectomy with some other devices may be quicker and more useful. although there is a learning curve which is very short, this tool is easy to handle. there has been no adverse effects. conclusions. the versajet-handpiece is a disposable product, but because of the advantages it is at least cost-covering. debridement is highly effective since it enables selective tissue targeting. removal of non-viable tissue is more complete as a result. background. in more than children (age < years) were suffering from burns. the gold standard of surgical care is still under discussion. the aim of the study was to evaluate an optimised treatment regime for scalds in children. methods. between and , children underwent surgical intervention due to salds. thirty-six of them were enrolled into the study. twenty-two children with deep dermal scalds (total-body-surface-area burned (tbsa) . %) were treated by early excision and keratinocyte-coverage (keratinocyte-group). fourteen children (tbsa . %) were treated with autologous skin grafts (skin-graft-group). both groups were comparable according to age, burn depth and tbsa. the complete clinical follow-up was at least months. the scar formations were classified (vancouver-scar-scale (vss) and the need of blood transfusions were administered. results. the use of keratinocytes led to complete epithelialisation. no secondary skin grafting was necessary. skin take rate was % in the skin-graft-group. the mean volume of transfused blood was . ml in the keratinocyte-group and thereby significantly lower than the volume of . ml, which was administered in the skin-graft-group (p ¼ . ). the vss observed in the keratinocyte-group was . and thereby significantly lower than the vss of . in the skin-graft-group (p ¼ . ). conclusions. in children the use of keratinocytes renders constantly reliable results in deep dermal scalds. it minimizes the areas of skin harvesting and reduces the amount of blood transfusions. the fact that also less scarring is observed leads to the conclusion that skin grafting should be restricted to full thickness scalds. background. ventriculo-peritoneal (vp) shunting is the treatment of choice for hydrocephalic children. however, serious complications related to infectious and non-infectious reasons may subsequently appear during lifetime of these patients. as we attend nearly all our patients from birth to adulthood we had to face various kinds of abdominal problems over the years. hydrocephalic children underwent vp shunt placement. outcome and follow-up of these patients were discussed. results. our analysis showed that non infectious complications like: shunt dislocation, kinking and obstruction including some rare phenomenon are well described in literature and can hardly be avoided. but being confronted with various infectious complications we had to change our strategy over the years. severe shunt infection appeared after appendicitis in patients. therefore we consequently performed elective appendectomies since . consecutively we had to face problems with following malone procedure. because of abdominal pseudo cysts after recurrent shunt revisions bacterial culturing methods and antibiotic therapy regimen changed. treatment of post haemorrhagic ventricular dilatation in premature very low birth weight infants had changed over the years from intervention with external drainage, early lumbar punctures, repeated ventricular punctures to implantation of the new ''side-inlet integra reservoir''. conclusions. the lesson we learned out of this retrospective analysis is that treatment of these hydrocephalic patients needs to be designed concerning all problems of the disease during life time period. therefore we think that experience and retrospective analysis is a very important point of view for the future. years' experience with lymphangiomas in children j. burtscher, e. horcher background. the management of lymphangioma in children is still challenging. complete resection is difficult to achieve in some cases and recurrences are common. methods. a retrospective study over a period of years was carried out. fifty-one patients were treated. males and female patients. the involved sites were head and neck, trunk and extremities as well as retroperitoneal, intraabdominal or intrathoracic location. prenatal mri was introduced to plan operative strategy especially for cervical location. results. there were recurrences. recurrence rate was highest in intrathoracal location. there was so significant differences, in terms of outcome, between those who had their surgery immediately at the time of diagnosis and those who had delayed surgery. conclusions. prenatal mri is a helpful tool in planning operative strategies like exit-procedure (ex utero intrapartumprocedure). risk factor for recurrence included location, size or complexity of lesion. background. hemangioma is the most frequent tumor in childhood. in more than % of cases hemangiomas are located in the face and the decision about the need for treatment, and the type of treatment may be difficult. complex hemangiomas need emergent systemic drug therapy, which may be combined with other types of interventional therapy, such as surgery or laser treatment. the aim of this study was to evaluate our experience in the treatment of complex hemangiomas. methods. analysis of complete records of patients who were treated in the period between . . and . . . results. out of patients referred to us, patients ( %) needed hospital treatment ( % girls), mainly because of rapid growth, and complications which were present in patients ( %). the most frequent localization of hemangiomas were the head and neck region ( %) and % of patients had multiple hemangiomas. median age at first referral was months, with % of patients referred to us before months of age. more than half of patients received their first treatment before months of age, and within days after referral. treatment consisted in laser therapy ( %), excision ( %), and additional (or exclusive) drug therapy in % of patients (cortisone, interferon). interdisciplinary treatment was necessary in patients ( %), involving mostly plastic surgeon, dermatologist, pediatric oncologist, pediatric radiologist, ophthalmologist, and psychotherapist. the majority of interdisciplinary treated patients ( %) received initial treatment in other centers, patients ( %) presented with complications, and rapid growth was present in % of patients. parotid hemangiomas (n ¼ ) were treated solely by systemic cortisone treatment (n ¼ ). intra-tracheal hemangiomas (n ¼ ) required often a laser treatment (n ¼ ), in addition to administration of systemic cortisone. massive segmental facial hemangiomas (n ¼ ) needed additional treatment with interferon (n ¼ ). in one case a phaces syndrome was diagnosed and the patient needed a complex therapy. conclusions. the need for treatment of hemangioma must be made on the individual basis. most hemangiomas need only observation. however, patients with complications and=or facial localization of hemangioma with rapid growth require often emergent treatment in medical centers with the possibility for an interdisciplinary management. early therapy may be a precondition for a good cosmetic result. background. treatment of appendicular peritonitis is closely connected with prophylaxis and treatment of surgical complications during postoperative period. the abscess of omentum major is one of such a complications, elsewhere discussed in medical literature. the aim of the study was the reduction in frequency of this complication. methods. during - years we treated patients with the abscess of caul. all of the patients were also treated for the appendicular peritonitis in the past. the time since the discharge from outpatient department to re-admission to the hospital varied within - days. the disease manifested with abdominal pain, increase in body temperature to the febrile grade. all the patients presented with tumour-like abdominal mass of various size. two patients presented with umbilical fistula and purulent effusion. abdominal ultrasound elicited masses with fluid content in patients. laboratory work-out revealed significant increase of tests relevant to endotoxicosis. all patients were operated. five patients underwent dissection of infiltrate, and the total resection of caul. two patients passed drainage of abscess through the anterior abdominal wall. results. all the patients recovered. complications of early and late postoperative period were not observed. patients were on the close follow-up for to years without any sequalae. hospitalisation span was . ae . days. conclusions. . abscess of caul can manifest during early as well as late postoperative period. . management of omental abscess: -complete resection within visually intact tissues; -careful washing of abdominal cavity with antiseptic solutions; -vigorous antibacterial therapy in postoperative period. beneficial effects of mixed hyperalimentation in children with septic form of acute hematogenic osteomyelitis a. albokrinov , a. pereyaslov lviv children's regional clinic hospital, lviv, ukraine; lviv d. halytsky national medical university, lviv, ukraine background. septic form of acute hematogenic osteomyelitis (aho) is severe sepsis with multiple organ dysfunction syndrome (mods) according to accp=sccm consensus conference committee, . mortality and morbidity rates from this remain unacceptably high, in spite of achievements in intensive care medicine. nutritional support is the method of intensive care with proven efficacy, but the ''perfect'' regimen of it is unknown. methods. in - in our clinic children with septic form of aho were treated. they received standard therapy of severe sepsis which included surgical treatment (osteoperforation, suppurative focus drainage, pleural drainage in case of pyopneumothorax), antibacterial therapy, hemodynamic support. all of patients were mechanically ventilated (mv) because of acute hypoxemic respiratory failure on the basis of metastatic pneumonia. regarding to nutritional regimen patients were randomized on two groups: control (enteral alimentation with isocaloric isonitrogenic diet fitting basic energy expenditure (bee) multiplied by coefficient . ), and basic (mixed enteral ( . bee) plus parenteral (protein ¼ g=kgÃday, energy ¼ . bee) hyperalimentation). results. there was strong tendency of patients in basic group to have less pulmonary complications, better gas exchange values, less ventilation days and less intensity of hypermetabolic-hypercatabolic syndrome (see table, à p < . ). conclusions. mixed enteral-parenteral hyperalimentation in children with septic form of aho is an effective method of prevention of pulmonary tissue destruction and respiratory function improvement. background. the aim of this study was to gain information about the mechanisms of injuries and injury pattern at primary and secondary schools in austria. methods. at the department of pediatric surgery in graz and six participating hospitals (klagenfurt, salzburg, steyr, krems, schladming and innsbruck) all children from to years presenting with trauma were included within a two year study period. in total, pediatric trauma cases were filed. data were analyzed regarding personal data, site of the accident, circumstances and mechanisms of accident and the related diagnosis. results. at the department of pediatric surgery, medical university of graz, questionnaires were completed, out of which children had suffered from school accidents ( %). questionnaires from outside hospitals included school accidents ( %) with a mean age of . years in the children from graz and . years in children from participating hospitals. the male=female ratio was : . in general, sport injuries lead to a higher rate of severe trauma ( % severe injuries) compared with other activities in and outside of the school building ( % severe injuries) with ball-sports being the most dangerous activity with a % proportion of severe injuries. over all, the upper extremity was most frequently injured ( %), followed by lower extremity ( %), head and neck area ( %) and injuries to thorax and abdomen ( %). conclusions. half of all school related injuries occur in children between and years of age. there are typical gender related mechanisms of accident: boys get frequently injured during soccer, violence, and collisions in and outside of the school building and during handicrafts. girls have the highest risk of injuries at ball sports other than soccer. background. objects and notably coins are frequently swallowed by children - years old. their precise management on asymptomatically passing the gastro-esophageal junction remains controversial. this study was performed to assess dissolution of specific metals from coins immersed in simulated gastric juice. methods. four types of euro and us coins were immersed in simulated gastric juice for , , and hours. six metals were evaluated by inductively coupled plasma-atomic control group (n ¼ ) basic group (n ¼ ) sofa, mean (sd) . ( . ) . conclusions. coins retained in the stomach will release a number of heavy metals well known to cause dose-dependent poisoning. studies to evaluate their toxicity and absorption are needed to optimize treatment. the surgical tactic on the splenic injury in children a. pereyaslov, s. chooklin, i. korinevska, a. troshkov medical university, lviv, ukraine splenectomy in children often leads to various complications. retrospectively, results of the management of children (range from to years), which underwent surgery due to the liens' injury, were examined. the immunological and hormonal investigations were performed. out of operations in the splenectomy, in cases the splenectomy with the tissue autotransplantation of the lien in the greater omentum and in cases the organ-preservation operations were performed. purulentseptic postoperative complications were noted in ( . %) patients, which connected with the inadequate of the immune answer. the obvious t-cellular immunodeficit, low concentration of igm, decrease of phagocytosis were observed in this category of patients. by that, on the background of activation of the renin-aldosteron system and changes of the eicosanoids synthesis, the danger of the sepsis and septic shock development were arisen. the autotransplantation of the lien tissue did not protect the organism from the purulent-septic complications in the nearest postoperative period. as the answer to the transplanted tissue and necrobiotic processes, which had been occurred in it, the autoimmune processes and reactions of the hypersensitivity of the immediate type (the increase of ige and dna antibodies levels) were intensified. with the goal to prevent complications in the postoperative period the thymic hormones, interferon a, aspirin and dipyridamol were applied. in the remote terms, the postsplenectomy syndrome manifested itself in patients, which underwent the splenectomy in childhood. predisposition to the infections and thrombohemorrhagic processes prevailed. the disturbances of hemostasis are linked with the significant increase of the t-helpers that connected with the intensifying of the il- action, which also evokes the proliferation of the preactivated b-lymphocytes, and, as the result, the obvious synthesis of igg. igg in the composition of the immune complexes can stimulate the function of the neutrophyles. all this promotes to transfering the hageman factor in the active condition, activation of the coagulative and kininogen-kinin blood system, intensification of the fibrinolysis, the deposit of fibrin and the development of the hemorrhages. the autotransplantation of the lien tissue could not enhance defence of the organism in full value. thus, at the traumatic injury of the spleen the prevalence must be given to the organpreserving operations. background. mri of the breasts has been described the most sensitive imaging modality for detection of multicentric or multifocal malignant tumor manifestations. in we began with routine preoperative mri-staging in breast cancer patients. the aim of this study is to analyse the benefit of preoperative mr-imaging regarding surgical treatment and follow up in patients with invasive breast cancer. methods. the retrospectice study (n ¼ ) includes all female patients with histologically verified invasive breast carcinoma, which have been operated at our department between and . exclusion criteria were carcinoma in situ, local recurrence, inflammatory carcinoma and neoadjuvant therapy. demographic, radiological, operative and histological data, standardized follow up (dfs, os) and recurrence rate were analysed. results. surgical treatment consisted in bct ( . %) and mrm ( . %). % of tumors showed an invasive ductal differentiation. lymph nodes were positive in %. tumor size showed the following pattern: pt %, pt % and pt = %. grading was . % (g i), % (g ii) and . % (g iii), respectively. mr-imaging revealed multifocal or multicentric tumor manifestations in % of patients, the mri results changed surgical treatment in % of cases. mean follow up was months. the local recurrence rate was . %, . % of patients developed carcinoma in the contralateral breast, incidence of distant metastases was . %. conclusions. the data confirm the importance of routinely performed mr-imaging in preoperative staging of breast cancer patients. mri-identification of multifocal or multicentric tumor manifestations is essential to choose the optimal surgical treatment and reach a minimal recurrence rate. methods. between july and october patients with operable breast cancer were treated at general hospital feldkirch. of subsequent patients with non-palpable lesions intraoperative sonography was used in (group ), wire localisation in cases (group ). the study was conducted as nonrandomised trial with prospective data collection. results. breast-conserving surgery was performed in % in group and % in group . primary r -resection was significantly higher in group ( %) than in group ( %, p < . ) while median clear margins were . and . mm in these groups (p < . ). both wire localisation and intraoperative sonography proved to be feasible with tumor identification rates of %. conclusions. intraoperative sonography proved to be reliable and feasible in breast cancer patients in the hands of the surgeon. clear advantages next to tumor identification and topographic orientation for excision were organisational acceleration and improvement: discomforting, time and labour intensive wire localisation can be avoided and breast lesions can be excised in a tissue-sparing and breast-conserving technique in a very high percentage. background. extensive intraductal disease represents an important clinical problem in the management of patients with invasive or in situ breast cancer. we present a new method for intraoperative ductoscopy with intraductal biopsy of suspicious lesions. methods. intraoperative ductoscopy was performed in women undergoing operation for breast cancer or nipple discharge. a rigid gradient index microendoscope ( . mm) with a special biopsy device for vacuum assisted biopsy was used for all examinations. ductoscopy findings were documented prospectively and correlated with preoperative mammography and histology of the resection specimen. results. ninety-two percent of the patients were examined successfully. ductoscopy identified intraductal lesions (ie, red patches, ductal obstruction, or microcalcifications) in % of the patients. abnormal ductoscopic appearance was found in more than % of the patients with extensive intraductal disease %. patients with an abnormal ductal appearance on ductoscopy, compared with those with a normal ductal appearance, had a greater incidence of extensive intraductal spread of cancer ( % vs. %) and a greater incidence of positive surgical margins ( % vs. %). ductoscopic biopsy of intraductal lesions was technically successful in all but one case. generally, the quality of the biopsy samples was good. diagnostic biopsy samples were obtained in of patients ( %). two samples contained necrosis and were considered to be non-representative. histological analysis of the biopsy specimens showed papilloma, in situ carcinoma and invasive carcinoma. conclusions. high-resolution ductoscopy is able to detect extensive intraductal disease in a considerable number of women with breast cancer. vaccum assisted biopsy allows intraductal tissue sampling of very small lesions. in selected patients, a combination of both preoperative imaging and intraoperative ductoscopy may help to avoid incomplete resections and re-excisions. background. preoperative chemotherapy (pc) for breast cancer was initially focused on locally advanced tumors. later on it has been established to downstage operable tumors primarily not suitable for breast conserving surgery. now pc is often used as an invivo test for chemotherapy regimens. methods. since the austrian breast and colorectal cancer study group (abcsg) conducted trials with pc. abcsg- analysed the effect of pre-and postoperative versus postoperative chemotherapy alone with cyclophohamide= methotrexate=fluorouracil. abcsg- compared versus cycles of epirubicin=docetaxel þ g-csf regarding the rate of pathologic complete response (pcr). abcsg- analysis the rate of pcr between cycles of epirubicin=docetaxel and cycles of epirubicin=docetaxel=capecitabine ae trastuzumab for her- positive patients. results. from to abcsg- enrolled eligible patients. after a follow up of years recurrence-free survival is worse in the pc arm (hr . , . - . ; p ¼ . ), overall survival doesn't differ significantly (hr . ; . - . ; p ¼ . ). patients were accrued to the abcsg- trial between and . the rate of pcr was significantly higher in patients after cycles than in those after cycles ( . % vs. , %; p ¼ . ). also significantly more patients had a negative axillary status after cycles than after only cycles ( . % vs. . % p ¼ . ). recruitment of abcsg- started in and is still ongoing. conclusions. while pc fails to improve prognosis so far, regimens which improve the rate of pcr have been found and we are still hoping to tranpose this effect in better prognosis. sentinel node biopsy performed before preoperative chemotherapy for axillary lymph node staging in breast cancer p. schrenk , c. tausch background. sentinel node (sn) biopsy following preoperative chemotherapy (pct) in breast cancer patients is associated with a lower identification rate (ir) and an increased false negative rate (fnr) compared to sn biopsy in patients with primary breast cancer. methods. sn biospy was performed in breast cancer patients with a clinical negative axilla prior to pct. following chemotherapy sn mapping was repeated and the current lymph node status was assessed with axillary lymph node dissection (alnd). results. sn mapping prior to chemotherapy successfully identified a mean of . sns in all patients (ir %). patients revealed a negative sn, a positive sn (micrometastasis in = ). following pct re-sn mapping was successful in = patients (ir %). ir for re-mapping was % for patients with a primary negative sn or a micrometastatic sn compared to % for patients with primary macrometastatic sns. none of the patients with a negative sn biopsy and none of the patients with micrometastasis prior to chemotherapy revealed positive lymph nodes following pct. contrary to that = patients with a macrometastasis prior to pct revealed positive nodes following chemotherapy, and this was irrespective of the type of tumor remission due to pct. the fnr of remapping was % and false negative sns were only found in patients with macromatastatic sns in the primary sn mapping. conclusions. patients with a negative sn biopsy or with a micrometastatic sn prior to pct may forego complete alnd following pct, whereas this may not be valid for patients with macrometastatic sns. sn biopsy following pct is associated with a low ir and a high fnr. background. standard pancreatoduodenectomy (pd) for the treatment of resectable tumors of the periampullary region or the pancreatic head involves a radical pancreatoduodenectomy with an extensive gastric resection. the modified whipple operation aims to preserve the stomach, pylorus and proximal duodenum so as to decrease postgastrectomy complications and improve the patient's quality of life. however, there were still many postoperative complications after pylorus-preserving pancreatoduodenectomy (ppd). unfortunately, in some retrospective studies tumors of the periampullary region and the ductal carcinoma of the pancreatic head are still not differentiated. this methodological problem and the improved surgical strategy (lymphadenectomy, etc.) in combination with the excellent histopathological diagnosis by experienced pathologists are decisive factors in determining the ultimate outcome as demonstrated. methods. patients (all treated at smz-süd -kaiser franz josef spital department of surgery) with a exocrine malignant tumor of the pancreatic head or periampullary region were retrospectively analyzed by comparing a year period before and after . results. in the last period of observation the complication rate and lethality was reduced (there was one cases of death because of technical reasons). the number of r resections (incl. mesoduodenum) improved from % to %. also the number of the resected lymphatic nodes increased from to ( - ). the actuarial year survival rate in patients after resection of a pancreatic ductal adenocarcinoma at r , n stage increased from % up to %. an increase in long-term survival could also be observed in the n-positive group. conclusions. at an oncologic center with optimal interdiciplinary collaboration of the different departments (internal medicine, surgery and pathology) a respectable actuarial year survival ( %) of the pancreatic ductal adenocarcinoma can be achieved without interfusing different tumorentities. the lethality caused by technical reasons should be almost %. detailed information will be discussed during the presentation. background. complete surgical resection remains the only potentially curative treatment, improving -year survival, for patients diagnosed with pancreatic cancer. preoperative administration of chemotherapy or combined radiochemotherapy may present a way in increasing the number of patients were radical surgical therapy is reasonable and feasible. lower perioperative mortality and morbidity rates are reported in high volume centres. methods. between jan. and dec. patients, diagnosed with locally advanced non metastatic pancreatic cancer, received preoperative chemotherapy with neoadjuvante intent. patients had curative surgery at time of diagnosis and adjuvant chemotherapy depending on their stage of disease. a subset of patients have been diagnosed at an far advanced stage of disease and were treated in palliative ways. results. the observed perioperative mortality rate was . % ( = ). a total of ( . %) patients required reoperation because of complications after curative resection. minor complications, which have been treated in conservative ways, occurred in . % of patients. sixteen patients ( = , . %) demonstrated sufficient tumor response to undergo surgical curative resection after neoadjuvante chemotherapy. in this group the median survival time was month ( . - . % ci). median survival time for patients who underwent curative tumor resection at the time of diagnosis, was month ( . - . % ci). for patients, unable to undergo curative surgery after neoadjuvant therapy (n ¼ ), median survival ( month, . - . % ci) did not differ from life expectance of primary palliative treated patients ( . - . % ci). conclusions. we suggest that in several patients, suffering from nonresectable cancer of the pancreas, preoperative chemotherapy significantly rises overall survival to a level so far reserved to patients with operable carcinoma. in other malignancies neoadjuvante chemotherapy is an accepted standard of cancer treatment. there are many potential advantages of neoadjuvant chemotherapeutic regimes for both resectable and advanced pancreatic carcinoma. novel targeted molecular therapies and their combination with established chemotherapeutic agents may lead to higher conversion rates after neoadjuvante therapy and improved -year survival rates in the near future. background. haemodynamic impairments after pneumonectomy are rare complications and present in two different forms or a combination of both. changes in the anatomical situation of the left atrium and elevated pulmonary artery pressure can lead to a significant right-left shunt via a previously closed foramen ovale (pfo) and diaphragmatic relaxation can lead to a dislocation of the liver into the right hemithorax, compressing the right atrium with subsequent inflow obstruction. methods. we retrospectively analysed our patient cohort from to for occurrence of haemodynamic complications requiring surgical intervention after pneumonectomy. results. five patients ( female, males, age ae years) were identified. all underwent right pneumonectomy due to nsclc (n ¼ ) or atypical carcinoid (n ¼ ). two patients were readmitted months and years postoperatively due to increasing platypnoea and orthodeoxia. after closure of a pfo which was found as the underlying pathological mechanism respiratory symptoms were resolved. one patient required reintubation already hours postoperatively; after surgical closure of a pfo the respiratory situation significantly improved. one patient was readmitted due to right atrial inflow obstruction months after right pneumonectomy. underlying cause was a severe diaphragmatic relaxation with compression of the atrium by the liver. after diaphragmatic plication all symptoms resolved. one patient was readmitted months after pneumonectomy and partial atrial resection due to cyanosis and dyspnoea. diagnostics revealed a pfo and a massive raise of the right diaphragm with compression of the right atrium. after surgical correction of the contorted foramen ovale and diaphragmatic plication symptoms vanished. conclusions. haemodynamic alterations due to a reopened foramen ovale or right atrial inflow obstruction are rare however severe complications after pneumonectomy. they occur at variable points in time after pneumonectomy. closure of the pfo either surgical or interventional and=or plication of the elevated diaphragm are mandatory. in our experience these complication occur only after right pneumonectomy. chronic sequels after thoracoscopic procedures for benign disease -long-term results j. hutter, s. reich-weinberger, h. j. stein background. video-assisted thoracic surgery (vats) is recognized to be as effective as open surgery for a variety of diagnostic and therapeutic conditions, but with significantly less morbidity. chronic postoperative pain (cpp) is defined as persisting more than months after the procedure. cpp and other neurological sensations like disesthesia or numbness are found frequently, but little is known about the outcome of those patients many years after the primary procedure. methods. in we retrospectively investigated a group ( . %) out of patients who were identified with sequels at a mean of months after a vats procedure. now at months post-operation we reinvestigated those patients for ongoing sequels. results. from patients were still alive and could be reached for an interview. ( %) were now free of symptoms while ( %) still suffered from sequels. from the group of patients operated on, sequels were now present in ( . % at months vs. . % at months, p ¼ . ) patients. pain was present in ( . vs. . %, p ¼ . ), in three ( . vs. . %, p< . ) even at rest, and in ( . vs. . %, p ¼ . ) patients only at exercise. ten ( . vs. . %, p ¼ . ) patients suffered from pain occasionally e.g. due to changing weather. painkillers were only taken by one ( . vs. . %, p< . ) patient occasionally, and the sequels impacted the life of one woman ( . vs. . %, p< . ) badly. numbness was present in . vs. . % (p ¼ . ) of patients. conclusions. early postoperative sequels are frequently found in vats procedures, but patients with pain even after years have a nearly % chance to eliminate their problems. in addition, numbness and disesthesia seem to disappear almost completely several years after the procedure. intrapulmonary injection of fibrin glue as a treatment of persistent parenchymal fistulas after pulmonary surgery: a case series s. b. watzka , h. redl , b. el nashef background. persistent parenchymal fistulas are a major problem after pulmonary operations particularly in lung emphysema patients. conventional surgical remedies, like over-suturing or stapling of injured lung surfaces are rarely efficient. here we present our preliminary experience with a novel application of fibrin glue as a sealant of persistent parenchymal fistulas. methods. patients with postoperative parenchymal fistulas persistent for more than six days, and not responding to conservative measures, underwent re-operation. lung surfaces not anymore suitable to reconstruction by suturing were sealed by peripheral intrapulmonary injection of fibrin glue. after discharge, the patients were regularly followed-up. in addition, the macroscopic distribution of injected fibrin within lung tissue has been investigated in a porcine in vitro lung preparation. a total of six patients underwent the above described procedure. the primary operation was upper lobectomy in four cases, laser resection in the upper lobe in one case, and empyema evacuation by vats in one case. the mean volume of injected fibrin was ae . ml. in five out of six patients the fistula was stopped permanently. in one case, however, the parenchymal fistula re-appeared and had to be treated by combined application of fibrin glue and hemostyptic tissues. after a mean follow-up of . ae . days, all patients are well and symptom-free. in the animal tissue preparation, the fibrin was macroscopically distributed exclusively in peripheral lung parenchyma. conclusions. in selected cases of persistent postoperative parenchymal fistulas, peripheral intrapulmonary injection of fibrin glue offers a low-risk and efficient surgical option. background. recent case-matched studies demonstrate that stage i non-small cell lung cancer (nsclc) in functionally inoperable patients can be treated by limited resection approaches without compromising the oncological result. the recently introduced -nm nd-yag laser enables the highly selective and parenchyma-saving excision of pulmonary lesions, and was thus originally designed for the removal of multiple lung metastases and more central lesions. in this prospective study, we are evaluating for the first time the mid-term results after local resection of stage i primary nsclc by laser knife in functionally inoperable patients as defined by predicted postoperative fev (ppofev ) less than %. methods. between and , functionally inoperable patients underwent local resection of stage i nsclc by -nm nd-yag laser. we assessed their postoperative course, tumor recurrence, and survival by statistical means. results. postoperative mortality was zero. three patients ( %) had minor surgical complications in the postoperative period (persistent air leak, delayed wound healing). the postoperative respiratory function was unchanged as compared to the pre-operative value. the median follow-up was . months (range - months). recurrence rates ( . %) and actuarial -year survival ( %) were comparable to standard lobectomy results, as reported in the literature. none of the three deaths observed during the follow-up period was cancer-related. conclusions. the -nm nd-yag laser enables the resection of stage i nsclc in functionally inoperable patients under complete preservation of respiratory function, but without jeopardizing the oncological outcome. zentrumsbildung breast-cancer centers -between european visions and regional feasibility h. hauser background. there have been major improvements in the western world in recent decades in early diagnosis of breast cancer, breast conservation and survival. nonetheless, there are blank spaces on the map of europa and very likely of austria as well, where diagnosis and treatment of breast cancer are not optimal. collecting and treating patients with diseases of the breast in a few defined ''breast centers'' should give every patient with breast cancer the same highest quality treatment. methods. in , a working group was formed in florence, italy, to define the tasks to be met by such a center. in , the results produced by this group were published (eusoma ) . the aim of this guideline was to improve quality and quality control in the treatment of breast cancer. one of the main demands made of a breast center is to treat at least new primary breast cancer cases per year. further, a multidisciplinary nucleus team specialized in the treatment of breast cancer should be in place and should hold regular interdisciplinary tumor conferences. this team should include a surgeon=gynecologist, radiologist, pathologist, medical oncologist, radiotherapist, breast-care nurse, data manager, etc.). results. as early as , roohan et al. (am j public health , ) showed that the probability of survival of breast-cancer patients was directly proportional to the treatment volume of the hospital. regardless of tumor stage, patients treated in a hospital that saw less than cases per year had a % higher mortality risk than those treated in hospitals with more than operated cases per year. an operation performed by a breast cancer specialist reduces the mortality risk by % in comparison to operations performed by non-specialists (gillis cr, hole dj bmj , ) . the results of dubois et al. ( ) and others also indicate a better outcome for breast cancer when patients are operated in a specialized hospital with a large number of cases and a suitable interdisciplinary environment. the minimum number of cases of primary new breast cancer cases per year and center recommended by eusoma (but with an evidence level of and so not scientifically verified) would reduce the number of breast centers in austria to about . an analysis of the austrian situation nonetheless showed that many small surgical units produced excellent results, with interdisciplinary cooperation, in some cases together with external services. conclusions. certified, highly qualified interdisciplinary breast centers are intended to provide breast-cancer patients with highest quality care. the extent to which the eusoma criteria can be adapted to the austrian situation remains to be seen. breast cancer centres -can quality only be achieved in high-volume-institutions? b. zeh, g. humpel, p. lechner background. discussion is ongoing about institutional caseload and technical equipment that both may be required for up-to-date-treatment of breast cancer. we present the network architecture our department of surgery at the danube clinics in tulln is part of, aiming at multi-disciplinary diagnosis and treatment of approx. cancer patients per year. methods. . diagnosis: mammogram, ultrasound and mri can -and shall -be performed in an outpatient setting, considering that a close partnership with an experienced radiologist has been established. this is true also for the imaging techniques for staging. . interventional diagnosis with core needle biopsy, mammotome + , ecc., should be left to the surgeon! this may facilitate localisation of a non-palpable lesion during the subsequent operation. . surgery for breast cancer is not that demanding per se, on condition that the technical equipments for sentinel biopsy, specimen radiography, and frozen section are at hand. the procedures must be left to permanent team if surgeons with an individual experience of more than cases each. . systemic adjuvant treatment requires the availability of a clinical oncologist, at our institution on a consultant basis. patients are treated in clinical trials whenever feasible, preferably in those launched by abcsg. . radiotherapy is typically performed on an outpatient basis, disregarding at which institution the previous operation was performed. . follow-up needs to be co-ordinated by a qualified physician. we have established an oncological outpatient department, but co-ordination could also be left to an office-based oncologist. the mandatory management tools for close follow-up as well as for the prevention of unnecessary examinations are it-support and a patient log-book. conclusions. being embedded in a multi-disciplinary network, our institution's self perception is that of a part in a ''virtual centre of excellence''. we think that we are not only able to provide high medical quality, but that this quality is also subject to external control by our partners. background. the expectancy of life of patients with intraabdominal malignancies and peritoneal dissemination is usually poor. the surgical approach of a combination therapy of complete resection of the primary cancer, the peritonectomy and a perioperative intraperitoneal chemotherapy was developed to improve the prognosis of these patients. this treatment is cost-intensive and associated with special technical expertises. the aim of this study was to determine the modalities and to discuss the feasibility of this approach. methods. since june , a combination-therapy of visceral resections, cytoreduction of the peritoneal cancer and a heated intraoperative intraperitoneal chemotherapy was performed in patients ( female, male, average age . years) with visceral malignancies and peritoneal carcinomatosis as a curative approach. the same procedure was designated for six more patients but was not performed because of inoperable tumor masses. mitomycin c ( mg=m ) was utilized for the intraperitoneal chemotherapy and applied to the abdomen using a heartlung machine to guarantee a steady circulation and to keep the intraperitoneal fluid at c. the handling with the chemotherapeutic substance required special protective clothing for the staff as well as the competent disposal of all used materials. results. a multi-visceral resection was performed in = patients. a complete cytoreduction (cc- ) was obtained in eight patients, in one a cc- and in another one a cc- situation remained. the average operative time was minutes (range - minutes). a peridural catheter was necessary for a sufficient postoperative pain therapy. the average time at the intensive care unit was . days (range - days) and the average hospitalization was . days (range - days). no complications were observed associated with the surgery. morbidity was determined by gastrointestinal symptoms like prolonged postoperative ileus. in the follow-up three patients had a recurrence of the malignancy, = with a cystadenocardinoma of the pancreas after three and five months, respectively, and = patients after months with a metastatic sigmoid carcinoma. one patient died eight months after surgery because of malignancy progress. the average expense of this treatment was . eur. conclusions. specialized centres may provide the logistics and expenses to establish this treatment innovation to the surgical approach of intraabdominal malignancies to extend the long-term survival of patients with otherwise poor outcome. prospective studies are needed for additional adjuvant and neoadjuvant concepts in diseases with peritoneal malignancies. background. rectal carcinoma needs careful preoperative staging. in our department neoadjuvant treatment with long term radiation and chemotherapy is standard in patients with carcinoma of low and middle part of the rectal wall. main prognostic factors for long term survival are r resection, sharp dissection of the mesorectal fascia without coning, distal resection margin of at least mm and complete lymph node dissection along the mesentery vessels. there is no recommendation about the lymph nodes that should minimally be dissected in this group of patients until now. methods. we consecutively evaluated patients after neoadjuvant radiochemotherapy (rct) and surgery in terms of survival, local recurrence, perioperative mortality and morbidity. tumor regression grading (trg) and number of dissected lymph nodes (ypn) were analysed and correlated with survival. results. in our series local recurrence rate was lower than %, the r resection rate reached % and sphincter preserving surgery was possible more than %. the median number of dissected lymph nodes (ypn) reached > , the perioperative morbidity was lower than %. especially leakage and anastomotic stenosis with the need for reoperation or dilatation are typical complications of radiation therapy. the tumor regression grade clearly correlates with outcome. conclusions. multimodality treatment of rectal carcinoma including preoperative radiochemotherapy (rct) is well standardised with good results in outcome and morbidity. we show that high numbers of lymph nodes even after rct can be collected and suggest a minimum account of at least . tumor regression grading is a marker with prognostic significance and should be taken into clinical-pathohistological classification. we suppose that some patients are overtreated with preoperative rct. to proof this hypothesis, a randomised multicenter trial -together with german cancer centers -based on mri diagnostic is currently planned. background. the incidence of (hpv)-associated disease of the anal canal is rising. efficient anal screening by cytology is hampered because of poor specificity. hpv testing is proposed in addition to pap testing for the detection of cervical neoplasia. the purpose of this study was to determine the usefulness of a hpv-dna detection test (hc ) to detect hpv-associated disease and to compare two different methods of sample collection. methods. in patients anal samples were obtained using a cervix brush and a dacron swab to test for hr-and lr-hpv-dna. qualitative (positive=negative) and quantitative (rlu's, relative light units) were obtained. patients positive for hpv dna underwent anoscopy. biopsies were taken from visible lesions. results. lr-hpv-dna was found in of patients ( . %) and hr-hpv-dna in of patients ( . %). dacron swab sampling yielded more positive results than sampling by cytobrush ( . % vs. . % for lr-hpv, p < . ; . % vs. . % for hr-hpv, p < . ). a positive correlation of rlus was found for both sampling methods in the total cohort (p< . ), and patients with positive results (p< . ). sampling with dacron swabs yielded higher rlu values compared to sampling with cervix brush for lr-hpv-dna and hr-hpv-dna. conclusions. anal screening for hpv-dna by hc is a useful method for detection of hpv-associated disease. sample collection using dacron swabs identifies more hpv-positive patients, and yields higher rlu values, than using the cervix brush. background. persistent human papilloma virus-(hpv-) infection, immunedeficiency (hikv, immunosuppression after organ transplantation) are known risk factors for anal intraepithelial neoplasia (ain) and squamous cell cancer (scc) of the anus. the incidence in high rik groups is rising (hivpositive, men who have sex with men (msm)). screening programms employing anal cytology or anal colposcopy have been implemented in these risk groups. however, sensitivity and specificity are low for both screening methods. since persistent hpv-infection seems to be a prerequisite for ain and scc it seems reasonable to use hpv-typing as an adjunct to screening in risk groups. methods. three hundred and eighty-five consecutive patients with hpv-associated anal disease were included. sexual orientation, hiv-status, smoking habits and psychological strain were documented. all patients underwent clinical examination, rigid sigmoidoscopy and anal hpv-testing. biopsies from macroscopically visible lesions were taken and categorized in condyloma or the three grade-scale of ain according to the bethesda terminology for reporting results in cervical histology. hpv-testing for low-risk (lr) and high-risk (hr)-types was performed using hybrid capture (hc ). qualitative (positive=negative) and semiquantitative results (relative loight units, rlu's) as an indirect measure of ''viral load'' were obtained. results. hiv-status was the only significant risk factor for hr-hpv-infection in univariate and multivariate analysis. in univariate analysis positive hiv-status and patients tested positive for hr-hpv-dna or both types of hpv-dna were significant risk factors for presence of any type of ain. smoking habits, presence of psychological stress and detection of lr-hpv-dna did not significantly influence presence of ain. in multivariate analysis only presence of hr-hpv-dna was a significant risk factor for ain. univariate interclass correlation showed a significant correlation between grade of anal dysplasia and presence of hr-hpv-dna, grade of anal dysplasia and smoking, grade of anal dysplasia and positive hiv-status, presence of lr-hpv-dna and hr-hpv-dna and presence of hr-hpv-dna and positive hiv-status mean number of rlus for hr-hpv-dna was . for hiv negative patients and . for hiv positive patients. there was also a significant difference in the number of rlus for hr-hpv-dna for different grades of anal dysplasia. this difference was only seen in hiv-positive patients, but not in hiv-negative patients. conclusions. our results show the strong relation between persistent hr-hpv-infection and grade of dyplasia. this warrants hpv-typing to be introduced as an adjunct to screening for ain in risk groups. human papillomavirus and anogenital lesions: burden of illness and basis for treatment f. aigner, e. gander, f. conrad background. human papillomavirus (hpv) infections in the anogenital region have become an immanent disease pattern in daily clinical routine. still there is ignorance concerning the etiology and course of hpv associated anogenital lesions, thus demanding an interdisciplinary approach to this disease, which affects more frequently younger individuals. high recurrence rates and the propensity of high-risk hpv associated lesions for malignant transformation (cervical=anal cancer) led to the assessment of diagnostic and treatment options within our association. methods. the results of a consensus meeting in the framework of the rd innsbruck coloproctology winter meeting based on this topic are presented. results. the incidence of anogenital hpv associated lesions (anogenital warts, anal and cervical intraepithelial neoplasia, ain and cin, and anal=cervical carcinoma) has dramatically increased over the last years. in our centre the number of patients presenting with anogenital warts has been doubled from to , closely associated with an increase of diagnosed anal cancers. in the last two years new cases of ain iii (mean age years; males, females), cases of ain ii (mean age years; males, females) and cases of ain i (mean age years; males, one female) were treated in our proctologic unit and introduced to the gynaecologists. treatment algorithm includes excision, electrocauterization or laservaporisation of perianal or anal warts or ain i, ii and anal ain iii on the one hand and radical excision of perianal ain iii on the other hand. immunomodulatory treatment with imiquimod (aldara + ) should be preferentially applied for recurrent anogenital warts. histological examination of suspect lesions has to be performed routinely. conclusions. hpv associated anogenital lesions should be treated by a multidisciplinary approach. histological investigation of the excised material should be performed routinely as well as patients' surveillance including standard anoscopy and colposcopy in a specialized unit. gigip: tissue engineering und implantat induzierte immunologische reaktionen th -immunresponse to xenogeneic matrix grafts t. meyer , k. schwarz , b. höcht pediatric surgery unit, department of surgery, würzburg, germany; department of anatomy, saarland university, homburg=saar, germany background. extracellular matrix (ecm) biomaterials of xenogeneic origin, such as lyoplant + , pelvicol + or surgis + are beginning to be used as acellular, resorbable bioscaffolds for tissue repair in pediatric surgery. although a vigorous immune response to ecm is expected, to date there has been evidence for only normal tissue regeneration without any accompanying rejection. the purpose of this study was to determine the reason for a lack of rejection. methods. full-thickness abdominal wall defects were created in wistar-wu rats and reconstructed with either a lyoplant + -matrix (b=braun aesculap, germany) or prolene +matrix (polypropylene-matrix [ppp], prolene + , ethicon germany). animals were checked daily for local and systemic complications in both treatment and control groups. bodyweight was recorded and the possible development of a hernia was monitored. after weeks the abdomen was reopened and adhesions to the intestine were determined. histopathology and immunohistochemistry were performed to evaluate the immunological reaction to the xenograft. results. compared to the untreated animals, all rats had a physiological growth and body weight curve: no wound infection could be observed throughout the experiment. only in one rat, treated with a ppp-matrix, an abdominal hernia developed at the implant site. all other animals showed excellent clinical recovery and cosmetic results. ppp animals showed a pronounced inflammatory response indicated by an increased number of fibroblasts. the lyoplant + -matrix implantation induced an infiltration of cd and cd positive cells. in addition an active neovascularization was found, observing a remodelling process. this inflammatory response was significantly milder than in ppp implanted rats. interestingly some cd positive cells were detected in the lyoplant + -group. conclusions. xenogeneic extracellular matrix, such as lyoplant + , induces an immune response, which is predominately th -like, comparable with a remodeling reaction rather than rejection. background. mesh graft infections after hernia repair are an awkward complication. in more extensive infections many surgeons recommend removal of the mesh, due to the difficulty to treat microbes in th infected artificial material. the vac system now offers a new possibility in the treatment of complicated wounds, including mesh infections. methods. in this study, records of patients with mesh graft infections after incisional abdominal wall hernia repair were retrospectively analysed who have been operated on between january st and february th at the department of surgery, general hospital vienna. results. of patients ( %, female and male) operated in the period of investigation were suffering from mesh graft infections ( vypro ii mesh, composix mesh and surgipro mesh). mean age of patients was years. mean duration of wound therapy was days. % of the patients had an extensive infection. in those, topical negative pressure therapy (vac) was used. this led to a preservation of % of meshes in this group. in patients with a wound smaller than cm, infection could be successfully treated in of cases ( %). the type of mesh had an influence, whether it could be preserved. all of vypro ii-mesh grafts ( %), of composix mesh ( %) and of surgipro mesh ( %) could be preserved by conservative treatment. conclusions. data suggest that vypro ii mesh grafts are superior to composix and surgipro mesh regarding mesh graft preservation in case of postoperative mesh graft infection. vac therapy should be considered for successful treatment of more extensive infection. finally, small wounds (< cm) seem to have a good prognosis for mesh graft preserving healing. background. revisional procedures after restrictive bariatric operations are necessary in increasing numbers of patients. these procedures may be performed laparoscopically but represent demanding and in some cases risky operations. a meticulous technique is mandatory in order to achieve good postoperative results. methods and results. laparoscopic roux-y gastric bypass is performed as revisional procedure after laparoscopic gastric banding, sleeve gastrectomy and vertical gastric banding. the indication for a transformation to gastric bypass is inadequate weight loss or weight regain and technical failures of procedures. formation of the gastric pouch may be difficult because of adhesions and formation of a capsula in case of banding. gastro-jejunostomy may be performed by different techniques. conclusions. revisional gastric bypass is a more complicated procedure than primary bypass. in order to achieve good results a number of technical details have to be respected. background. laparoscopic sleeve gastrectomy has become a standard bariatic procedure in the last five years. this procedure has been performed with a number of different techniques using laparoscopic staplers and mobilizing the greater curvuture as primary step of the operation. methods. sleeve gastrectomy with a modified technique starting with the formation of the gastric sleeve prior to mobilisation of the greater curvuture is demonstrated. stapling is performed with linear straight staplers. conclusions. the advanages of performing laparascopic sleeve gastrectomy by a modified technique are shorter operating times, and a better overview especially near the his angle. the modified technique may therefore become a surgical standard in bariatric surgery. we present a video showing the technique of laparoscopic approach for reoperation on cases with complications due to ''lost gallstones'' after laparoscopic cholecystectomy. case is a years old female patient, operated for symptomatic cholecystolithiasis in august . in august she presented with right upper quadrant pain, the computertomography revealed a liver abscess in the right lobe and a retroperitoneal abscess. case is a years old male patient, operated for symptomatic cholecystolithiasis in november . in july he presented with right upper quadrant abdominal pain, the computertomography showed a small suspected abscess formation between liver segment and the right kidney. laparoscopic reoperation was performed the day after diagnosis. in case after adhesiolysis the liver was elevated and the abscess opened to perform rinsage and drainage of the cavity. the ''lost gallstones'' were taken out with a suction device. in case multiple stones were found in the upper abdomen under the peritoneum and in the abscess cavity. adhesiolysis and rinsage was performed. if abscess formation around the liver is seen even years after laparoscopic cholecystectomy, the diagnosis of a complication from ''lost gallstones'' should be suspected. reoperations for ''lost gallstones'' after laparoscopic cholecystectomy can be performed by laparoscopy if the abscess formation is accessible; results will be superior to ct-guided drainage due to the stone extraction by laparoscopy. grundlagen. die isr ist eine technik, bei der auch tiefsitzende karzinome des rektum sphinktererhaltend reseziert werden können. wir haben kürzlich eine operationstechnik entwickelt, bei der dieser eingriff laparoskopisch ohne großen zusätzlichen zeitaufwand durchgeführt werden kann. methodik. dieser eingriff wird nach genauer präoperativer abklärung durch ) digitalbefund, ) endoskopie und biopsie, ) mrt des rektums und ) sphinktermanometrie geplant. ausschließungsgründe für die operation sind: undifferenzierter tumor, t -stadium und schlechte sphinkterfunktion. der abdominelle teil wird im trokarttechnik (  mm optikport,  mm arbeitsport) durchgeführt. die präparation erfolgt entweder mit dem mm ultracision oder dem mm ligasure-atlas. der eingriff wird synchron von abdominell und peranal von teams durchgeführt. dafür wurde eine eigene lagerungstechnik entwickelt. die operation verläuft in folgenden phasen: ) totale mesorektale exzision, ) peranale intersphinktäre resektion des rektum ) bildung eines axialen kolonpouches, ) durchzug des kolon und koloanale anastomose, ) protektive transversostomie oder ileostomie. die präparatbergung erfolgt von peranal, sodass keine zusätzliche inzision am abdomen notwendig ist. der stomaverschluß erfolgt nach wochen. ergebnisse. von den insgesamt intersphinktären resektionen wurden laparoskopisch durchgeführt. die mittleren operationszeiten betrugen bei der offenen isr min, bei der laparoskopischen min. schlussfolgerungen. die laparoskopische intersphinktäre resektion ist ein praktikables operationsverfahren, dass mit vertretbarem zeitaufwand durchgeführt werden kann. die vorteile der laparoskopischen vorgangsweise können derzeit bis auf das hervorragende kosmetische ergebnis noch nicht abgeschätzt werden. schlussfolgerungen. der konsequente einsatz eines hochthorakalen pdks mit adäquater füllung zur schmerztherapie und sympathikolyse war von unserer anästhesieabteilung nicht regelhaft umsetzbar, so dass wir in der oralen gabe von oxycodon plus oraler stimulation des gastrointestinaltraktes eine hervorragende alternative zur durchführung der fast-track-rehabilitation gefunden haben. unsere ergebnisse decken sich mit den resultaten die derzeit von den chirurgischen zentren publiziert werden. die wiederaufnahme-( . %) und die gesamtkomplikationsrate ( %) ist bei längerer verweildauer etwas niedriger. unsere ergebnisse zeigen, dass das konzept der fast-track-rehabilitation gut in einem nicht ausgewählten patientengut umsetzbar ist. aufgrund der ausbildungssituation ist die zahl der lap. eingriffe relativ gering.in der oralen opiod-analgesie haben wir eine unerwartet gute alternative zum pdk gefunden. fast track surgery without thoracic peridural anaesthesia? background. thoracic pda is considered to be one of the main pillars of fast track surgery (fts). our anaesthetists being reluctant to perform thoracic pda as a routine, we decided to make an attempt to do surgery without thoracic pda yet following all other criteria of fts. methods. between jan. and dec. we have performed elective colonic procedures following our modified criteria. in these patients we have prospectively examined those parameters which could be expected to be influenced the most by pda: -postoperative intestinal paralysis -postoperative pain control -rate of complications results. the postoperative need of antiemetic drugs and the time of the first clinical signs of bowel activity (passing winds or stool) were examined as criteria for postoperative paralysis: - . % of patients never needed an anitemetic drug - . % of patients were having bowel activity not later than on po day standard postoperative pain control regimen contained two doses of mg paracetamol and two doses of mg diclofenac iv. as long as needed followed by the same combination given orally. mg of piritramid sc. was presribed as reserve treatment. - % of patients needed the standard iv-regimen for longer than three days - % of patients never needed a single dose of piritramid - . % of patients needed more than two doses of piritramid in the last months of the study only patients ( . %) needed piritramid for sufficient pain control (learning curve of nurses and doctors!). overall we have seen complications ( . % of procedures): background. multimodal fast track rehabilitation is based on modified perioperative fluid management, avoidance of preoperative fasting, effective analgesic therapy using epidural anesthesia, early postoperative mobilisation and immediate oral nutrition in order to accelerate recovery, reduce general morbidity and decrease length of hospital stay. young people seem to be the most suitable patients for fast track rehabilitation, but majority of the patients requiring colorectal surgery is older than years and often has several comorbidities. in this analysis we compared ''fast track'' feasibility and efficacy in young and old patients to examine, whether an age dependent management is required. methods. during one year all patients scheduled for colorectal surgery for colorectal cancer or sigmadiverticulitis on one ward were treated according to our multimodal ''fast track'' program. demographic and perioperative data, postoperative follow up (e.g. first bowel movement, vomiting, intravenous infusion therapy, fluid balance), local and general complications were prospectively assessed and evaluated on the basis of two groups (group a: age< a, n ¼ ; group b: age> a, n ¼ ). results. median postoperative hospital stay was days (a) and . days (b) with one readmission in both groups. the incidence of local and general complications was . % and %, respectively. a aged patient with stenotic rectal cancer with liver metastases and parkinsons disease died because of multiorgan failure. conclusions. the multimodal ''fast track'' rehabilitation concept is feasible in young and old patients. although older patients have a higher morbidity, our data show, that especially older patients benefit from enhanced recovery programs. background. the restrictive perioperative intravenous (i.v.) fluid management is an important element of multimodal fast track surgery. recent studies have shown a better outcome for patients with moderate or restrictive intravenous i.v. fluid therapy, but adequate interdisciplinary standards are missing and therefore optimal perioperative fluid management still remains controversial. in october we started ''fast track'' treatment in colorectal surgery on one ward, in this study we present our experience with modified perioperative fluid management. methods. during one year consecutive patients underwent elective surgery for colorectal cancer or sigmadiverticulitis ( laparoscopically, conventionally). demographic, pre-, intra-and postoperative data (e.g. fluid supply, urine excretion, creatinine, electrolytes, first bowel movement, vomiting), local and general complications were prospectively assessed and evaluated, median age of patients was years ( - years). results. intraoperative i.v. fluid administration was . ml=h=kg. on the first postoperative day patients oral intake was ml ( - ml) with an urine excretion of ml ( - ml). no hypovolemia associated complications were observed, creatinine and electrolytes showed no significant pre-and postoperative changes. general morbidity was % (urinary tract infection, pneumonia). median postoperative hospital stay was days (no readmissions). conclusions. reduced intraoperative and restrictive postoperative i.v. fluid therapy is feasible and has no negative impact on water and electrolyte balance. early oral fluid administration guarantees a sufficient hydration with adequate urinary output and contributes significantly to fast (track) rehabilitation and improvement of patients comfort. background. malignant pleural mesothelioma is a mainly asbestos-related neoplasm with increasing frequency associated with a poor prognosis. extrapleural pneumonectomy was initially performed as a stand-alone treatment in patients with respectable disease, however is currently almost uniformely applied as part of a multi-modal approach. its value and advantage over other therapeutic strategies remain point of discussion. we therefore analysed our experience with extrapleural pneumonectomy in the treatment of malignant pleural mesothelioma. methods. we retrospectively reviewed our institutional experience with all consecutive patients undergoing extrapleural pneumonectomy for malignant pleural mesothelioma from to . patients were analysed with regard to hospital data and outcome. results. forty-nine patients ( females= males, mean age ae years) underwent extrapleural pneumonectomy during the observation period. median icu stay was day, median postoperative length of hospital stay was days. after a mean follow-up of days median survival was days (mean ae days, range - ). year survival was . %, years survival . % and years survival . %. conclusions. extrapleural pneumonectomy as part of a multi-modal treatment regimen is a good treatment option for selected patients with malignant pleural mesothelioma. the long term results of this limited series compare favourable to non-surgical treatment regimens. larger randomised prospective multi-center trials are warranted to establish clear guidelines. background. the accelerated progress in genomics and data analysis technologies give a new view to customized treatment for stage iii lung cancer. the histopathological diagnosis will be accompanied by molecular classification. present treatment for advanced lung cancer is unsatisfactory and nearly % of newly diagnosed patients will die within two years. methods. from to patients underwent neoadjuvant treatment with platin-based chemotherapy followed by surgical resection. a panel of genes (p , p , mib- , cyclind , cycline, ercc ) were identified in pre-and posttherapeutic specimens. the expression profile was correlated to the histological regression grade and survival. results. the investigated different pathways allow an explanation of platin-based chemotherapy resistance and short duration of response according to the gene expression levels. conclusions. a prediction of a patient's prognosis could be improved by combining standard clinical staging methods with molecular-pathological evaluation. background. in the last years the video assisted approach (vats) has become the standard of care for persistent or recurrent (after tube drainage) spontaneous pneumothorax (sp) . but what is the standard treatment in recurrent pneumothorax after primary operation in the era of vats? moreover, we only have little information about the rate of contra lateral pneumothorax in those patients. to find answers to these questions we investigated the patients operated for sp in recent years. methods. we retrospectively analysed patients with sp treated by vats between = and = . only patients with years of age or younger without any underlying chronic lung disease were included. the treatment of choice was bullectomy or apical lung resection with apical partial pleurectomy (app) by vats. results. we identified patients at a mean age of years ( - ) with the female: male ratio of : . . the interval of the study and the operation was at mean of months. the primary vats for sp was successful in % (n ¼ patients). in three patients with primary failure persisting pneumothorax was reoperated by vats (postoperative day , , ) . none of these three patients had a recurrence. of patients treated successfully for spontaneous pneumothorax . % (n ¼ patients) suffered from recurrence at a mean of ( - ) months with one case of a second recurrence. only minor or no adhesions were found at the apex of the thoracic cavity, a bulla was found in one woman. moreover, in all patients an intact neopleura was found. major morbidity was postoperative hemothorax treated conservatively in % (n ¼ patients). interestingly, % (n ¼ patients) developed primary pneumothorax on the contra lateral side at a mean . ( - ) months. all these patients underwent vats without recurrence. conclusions. . successful treatment of sp can be achieved by vats with low recurrence rate, low morbidity and a high primary success rate. . in sp with bullae the role of app is not defined as yet and in recurrence or primary failure a thoracoscopic pleurodesis e.g. with talcum, should be considered. . in the light of the high rate of almost % of contra lateral sp a primary intervention on both sides should be considered. . a study to identify patients of risk for contra lateral sp with e.g. low dose ct in the first event should be considered. background. surgical treatment of myasthenia gravis and thymoma necessitates the complete resection of the thymus with the whole fatty tissue adherent to the pericardium. the aim was to investigate the efficacy and safety of robotic approach. methods. from = to = patients with myasthenia gravis (n ¼ ) or thymoma (n ¼ ) (mean age ae years, male to female ratio : ) were operated with the intention to perform a totally endoscopic, complete resection with the davinci telemanipulator system. in all but one patient a left sided approach was chosen. results. in out of patients the operation was carried out totally endoscopic. two patients had to be converted because of bleeding (patient ) and thymus carcinoma (patient ) requiring extensive resection. in the remaining patients, operative time was ae minutes, intubation time ae minutes. icu stay was day, in hospital ae . days. in all patients it was possible to identify both phrenic nerves and the complete fatty tissue above the anonymal vein along the supraaortal vessels was resected. histology revealed normal persisting thymus tissue (n ¼ ) and thymoma (n ¼ ) -who stage b and b (in cases each); masaoka stage i (n ¼ ), ii (n ¼ ) and ivb (n ¼ ), respectively. all resection borders were free of tumor. in all myasthenia gravis patients acethylcholinereceptor antibodies decreased during follow up. conclusions. complete endoscopic thymus surgery with the da vinci surgical system, is feasible and safe to implement into clinical practice. due to the minimal trauma, patients can return to full activity in a short time period. self-expandable covered metal tracheal type stent for sealing cervical anastomotic leak after esophagectomy and gastric pull-up: pitfalls and possibilities background. the rate of anastomotic leakage after cervical esophagogastrostomy following esophagectomy and reconstruction with the tabulated stomach ranges between and %. the treatment options comprise redo-surgery, endoscopical stapling, glueing or insertion of plastic stents, or conservative management with drainage procedures. the aim of this study was to evaluate the efficacy of self-expandable covered metal tracheal type stents for sealing the anastomotic leak. methods. from = to = , patients with leakage of the cervical esopahgogastrostomy following esophagectomy and reconstruction underwent endoscopic stenting using the self-expandable covered tracheal type device. the extent of the dehiscences ranged from to % of the anastomotic circumference. mortality, morbidity, healing rate of the anastomosis and hospitalisation time were evaluated. results. in all cases stenting was done without any complication. stent extraction could be performed after an average period of days, ranging from to days. in all cases, healing of the anastomosis was satisfactory. patients developed stenosis after removal which was successfully managed by bouginage. stent migration was observed in patients, treated by repositioning in one and two attempts of re-stenting followed by eventual suturing of a small residual leak in the other. conclusions. endoscopic insertion of a self-expandable covered metal tracheal stent represents a safe approach resulting in immediate closure and subsequent healing of cervical anastomotic leakage. there was no leakage-related morbidity, oral intake of food was resumed one day after successful stenting. however, stent dislocation and stricture after stent removal may occur. background. squamous-lined cyst of the pancreas is a rare entity with only about one hundred reported cases. three types of cysts are differentiated: lymphoepithelial, dermoid and accessory-splenic epidermoid cysts. the literature on this entity is limited to reports of single or small numbers of cases. the two most common cystic tumors of the pancreas are serous cyst adenoma and mucinous cystic neoplasms. we herein report the case of a lymphoepithelial cyst of the pancreas. case report. a -year-old man presented with a month history of upper abdominal pain and bloating. the disorders were related to food ingestion and were not followed by nausea or vomiting. he experienced low weight loss. he was in good general health with a normal physical examination and no tenderness in the upper abdomen. laboratory investigation including ca - , cea and hcg were within the normal range. imaging studies with ct, mrt and eus showed a  cm mass in the uncinate process of pancreas with contact on to the mesenterial vessels. the mass presented in ct=eus as a solid, expansive tumor, whereas mrt showed a cystic mass. fine-needle biopsy revealed squamous epithelial cells with sebaceous material, but without atypia. because of the progressive symptoms with compression of the duodenum and to rule out malignancy we resected the cystic tumor. no encasement, invasion or other aspects of malignancy were found. the resection defect was drained with a jejunal y-roux-loop. histological findings showed a benign lymphoepithelial cyst and the patient had an uneventful postoperative and four-month follow-up period. conclusions. establishing a preoperative diagnosis of a lymphoepithelial cyst is not possible. squamous-lined cysts of the pancreas have a low malignant potential, however, there are reports of mature dermoid cysts developing into malignant forms. to distinguish squamous-lined cysts from other cystic lesions of the pancreas, particularly malignant processes, is rather difficult. therefore we recommend a complete surgical removal of every cystic lesion suspicious to be a squamouslined cyst to avoid or treat malignancy. ten year experience with duodenum preserving pancreatic head resection in chronic pancreatitis r. j. klug, f. kurz, m. aufschnaiter kh barmherzige schwestern linz, chirurgie, linz, austria background. the chronic head accentuated pancreatitis is on the rise in industrialised countries. alcohol is the predominant aetiological factor.the incidence is per . inhabitants. in up to % of patients with chronic pancreatitis the head of the gland will be grossly enlarged by an inflammatory mass, often associated with bile duct stenosis and duodenal hold-up.in our institution the standard whipple operation has been replaced by the duodenum preserving pancreatic head resection (dpphr). methods. we present our meanwhile year experience with dpphr. our patients are analysed retrospectively. results. between november and november we performed dpphr in males and females patients. the average age was . years ( - years). the follow-up was done by the aid of an inventory referring to postoperative pain control, development of diabetes, postoperative weight gain and subjective success assessment. the complications are described and discussed as well. the results are presented. conclusions. the dpphr developed by beger about years ago has become the standard procedure for the operative treatment of.chronic head accentuated pancreatitis in our institution. the intervention is demanding but offers the advantages of maximal organ preservation, satisfactory endocrinological and functional results, a justifiable low complication rate as well as a high degree of satisfaction on the part of the patients. segmental duodenectomy at periampullary lesions -an adequate therapy? j. karner, b. sobhian, m. klimpfinger, g. udvadi, f. sellner smz-süd kaiser franz josef spital, vienna, austria background. the radical surgical procedure for treatment of the resectable periampullary tumors is the partial pancreatoduodenectomy or the pylorus-preserving pancreatectomy. in rare selected cases a segmental duodenectomy with reinsertion of the pancreatic and choledochus duct might be suitable alternative to improve the patient's quality of life. methods. about to patients were hospitalized annually with the diagnosis of a pancreatic or periampullary tumor at the smz-süd -kaiser franz josef spital department of surgery. to ensure radical resection either a partial pancreatoduodenectomy or a pylorus-preserving pancreatectomy was performed. in two patients with low-and=or high-grade dyspla-sia of the papilla and the peripapillar mucosa a segmental duodenectomy with resection of the papilla vateri was performed. after radical excision (proven by an intraoperative frozensection diagnosis) a duodeno-duodenal anastomosis with reinsertion of the splinted pancreatic and choledochus duct was performed. results. the postoperative course was uneventful. three months after the operation, clinical follow-up including gastroscopy revealed a normal mucosa of the duodenum and an excellent quality of life. conclusions. accurate surgical technique and pre-(gastroscopy), intra-and final histopathological diagnosis by an experienced pathologist are decisive factors in determining the ultimate outcome. if the histological findings as to benignity are uncertain, resection of the head of the pancreas with or without preservation of the pylorus by an experienced surgeon is indicated. the segmental duodenectomy might be an adequate therapy of the periampullary lesions in carefully selected cases. background. five randomized trials and an increasing number of phase studies confirm the opinion that the combination of peritonectomy-procedures and intraperitoneal chemotherapy positively influence the outcome in patients suffering from peritoneal carinomatosis (pc) of appendiceal tumors, colon cancer, ovarian cancer and gastric cancer as well as rare tumors of the peritoneum per se. nevertheless, according to the literature postoperative mortality was observed in - %, postoperative minor and major morbidity in - %. methods. in the last years patients (pts) suffering from pc arising from different primary tumors were treated at our institution in cooperation with surgical, gynecological or oncological departments in austria and germany. at the time of writing complete records from patients (mean age: . ae yrs, others ) are evaluated for analysis. primary objectives to assess were overall survival and time to progression of intraperitoneal or general disease. factors influencing these parameters were determined. secondary objectives to assess were postoperative mortality and morbidity. results. completeness of cytoredutive surgery, favourable histology (ovary, appendix, colon) and n -stage - (n ¼ pts) made a -year survival rate of % and a -year survival rate of % possible. (updated extended analysis of the different groups of patients will be presented) postoperative mortality within days was . %, within days . %. conclusions. cytoreductive surgery in combination with intraperitoneal, hyperthermic chemoperfusion ae systemic chemotherapy has a curative potential in selected patients. background. an increasing amount of patients confronted with an incurable or chronic progressive disease demands a special palliative procedure in physical, psychosocial and spiritual treatment. medical and nursing staff members in the hospital are not always prepared to handle with these patients and their relatives in a proper way. reasons behind may be lack of time, skills and experiences. deficits in management and in multiprofessional communication complicate the situation. a palliative liaison service provides, in this context, support in pain management, control of severe symptoms, treatment of terminal patients, coordination of professionals, discharge management, cooperation with mobile hospiz teams and support in ethical conflicts. methods. in we asked medical and nursing staff members for the importance and the need of palliative support in their daily routine. from may to december we documented consultations of patients, which means an effort of , hours. in we asked members of the medical and nursing staff in leading positions about the amount of satisfication with the provided support and the acceptance of the instution pls year after the implementation. results. in % of the staff members asked, confirmed the importance of palliative care and % agreed to the cooperation with a palliative liaison service. from may to december , , % of the demands for support came from surgical wards. the primary reasons for the first contact were pains and other severe symptoms. about % of the patients had cancer in the diagnosis. in the extent of satisfaction with the performances of the palliative support team was between , and , (satisfaction is defined until , within a range of to ). % to % from the provided performances were already requested. conclusions. the service of a palliative support team in the hospital was highly accepted already after a short time. more than the half of the consultations took place on surgical wards. we conclude that a palliative support service provides benefits for staff and patients in a difficult situation. especially in a time of rapid medical progress, limited resources and increasing ethical demands of autonome patients, the public health institutions may request for the right balance between curative and palliative settings. background. the ileus is often the sign of an advanced stage of malicious illnesses that require palliative treatment. medicine and especially palliative medicine has changed medical treatment in the way that it now aims at an improvement of life quality. methods. in our hospital cases with patients were analysed. these patients suffered from ileus in connection with an advanced malicious illness. results. an ileus was localised with patients in the field of the small intestine and with patients in the field of colon. cases were treated in a conservative way, cases required operative treatment. primary tumors were found predominantly in the colon and also in the feminine genitals as well as in the stomach. on average the remaining life time was two months. % of the patients with ileus in the field of the small intestine were treated without operation. conclusions. the life time of patients with ileus and advanced malicious illness is short. operations with high risk should be avoided. patients with ileus in the field of the small intestine should be given conservative treatment which in case of failing may be converted into interventional or operative treatment. operation can hardly be avoided with patients with ileus in the field of colon. if available, interventional therapy for the removal of stomach and intestine contents should be applied. the patient's wish is to be considered. treatment should aim at improving the patient's life quality. penetrating abdomino-thoracic injuriesreport of four impressive cases z. halloul, f. eder, f. meyer, h. lippert department of surgery, university hospital, magdeburg, germany background. penetrating wounds are distinguished in impalement and gun shot or stab wounds (stab=impalement injuries more frequently in europe), which are often very spectacular. the aim of the representative case reports is to analyze the kind of injury þ the adequate surgical, in particular, the complex wound management. methods. the impressive case series includes patients with abdomino-thoracic penetrating traumas ( stab=impalement wounds each) who were treated in a surgical university hospital centre during months. results. ( ) impalement injury by a steel pipe i) entering the body above the right kidney behind the liver, through the mediastinum via the right thorax, passed heart and aortic arch up to the left clavicle, ii) approached with sternotomy=median laparotomy to remove the rod including suture of the left subclavian vein only (postoperatively, residual lesion of the left brachial plexus=temporary pneumonia). ( ) one leg of a chair drilled into the left ''foramen obturatorium'' leaving the body at the right anterior iliac spine: initial removal=excision of the gluteal penetration canal. developing abdominal signs= symptoms indicated explorative laparotomy revealing peritonitis because of perforated ileum: segmental resection= anastomosis (postoperatively, i) right inguinal wound necrosis requiring excision=vacuum-assisted closure sealing; ii) remaining paresthesia in the left leg due to sacral plexus lesion). ( ) due to a violent conflict, stabs entered the right thorax while one injured the right pulmonary lobe=diaphragm=liver dome between segment viii&v þ a big scalp avulsion at the left= right parietooccipital site þ a transection of the right biceps muscle approached with right subcostal incision=anterior thor-acotomy=liver packing ( towels removed after d)=suture of the diaphragm=pleural drainages. ( ) stab injury at the left thorax (pneumothorax=lesions of the diaphragm & left third of the transversal colon) and neck (lesions of the pharynx=internal jugular vein) approached with left thoracic drainage=suture of the colonic & diaphragmatic lesions (postoperatively, i) right thoracotomy because of a right pleural empyema due to bronchopneumonia as a consequence of the blunt right thoracic trauma; ii) relaparotomy because of an abscess within the douglas' space; iii) billroth-ii gastric resection because of recurrent forrest-ia bleeding). conclusions. important aspects of such trauma care are immediate life-saving measures, transferral to a trauma centre, first care, prompt diagnostic=initiation of an adequate surgical treatment provided by trauma=general=abdominal=vascular and=or cardiac surgeons (e.g., surgical interventions at vessels= organs=soft tissue) as well as the postoperative course and rehabilitation. if these measures are provided with high medical standards and an interdisciplinary setting, optimal outcome can be achieved in order to prevent fatal outcome, to ensure maximal organ function, and to minimize permanent damages. background. today infections with clostridium perfringens are rare, but still most of the cases turn out lethal, although receiving timely medical treatment. this report deals with three different patients, who were transferred to our surgical department since june . the first patient (male ), with the suspected diagnosis ''femoral hematoma'', a second patient (male ) because of an ''acute abdomen'' and the third patient with suspicion of gas gangrene after chronic ulcer of the right food. methods. first patient: already at the physical examination of the femoral an impressive crepitation was palpable. besides this the man was suffering from myelodysplasia and showed a marked ulcer on the left side of the scrotum. on suspicion of gas gangrene we performed an exarticulation of the left femoral after intensive-care stabilization. besides all efforts this patient died the same day because of an acute circulatory failure. second patient: because of an acute abdomen the second patient received a ct and in suspicion of appendicitis an explorative laparotomy was indicated. furthermore a known haematoma at the right shoulder began to extend in sizeand shortly after the typical crepitation was palpable as well. even though the arm was exarticulated during an immediate operation the patient died because of the massive progressing infection. third patient: this patient was sent to our hospital because of the suspicion of gas-gangrene. during physical examination the typical crepitation was palpable at the right femoral and lower leg with associated emphysema. during operation the wound seemed unsuspicious. immediate examination of the tissue (department of hygienic and microbiology) showed a negative result concerning an infection with clostridum perfringens, so it could be refrained from an amputation of the femoral. entirely some incisions of the skin and the fascia were done. postoperative we kept watch on the wound in short intervals -showing consistent results the patient was transferred to our general ward to be treated because of his chronic ulcer on the right leg. conclusions. once pandora's box has been opened, still % of all gas-gangrene-infections pass off lethal. the first two cases demonstrate that (besides the low incidence of . events per mio. persons and year) infections of clostridum perfringens should always be kept in mind, especially in high-riskpatients. in contrast to this the third patient shows, that severe consequences because of a precipitate indication can be avoided by experience and careful evaluation. results. altogether patients were treated for rsh at our institution during the study period. seven patients were on oral anticoagulation, patients were taking acetylsalicylic, was on clopidogrel and patient was on anticoagulation with low dose heparin, whereas patients had no anticoagulation. a previous trauma event was apparent in six of the cases, one of this patient was on oral anticoagulation, one on acetylsalicylic, one was taking clopidogrel and three had no anticoagulation. rsh was correctly identified by means of ultrasound in of cases, in which this investigation was performed. a ct scan investigation demonstrated the haematoma in all ( of cases) cases. thirteen patients were managed conservatively, patients underwent surgical treatment. eight patients needed blood transfusion and four patients received vitamin k medication. all patients could be discharged from hospital in good general condition. clinical re-evaluation (median follow up years, range month- years) showed all patients were free of symptoms at this time. conclusions. our data confirm the multifactorial aetiology of rsh and the strong association with different forms of anticoagulation. ct scan is the diagnostic tool of choice, whereas identification with ultrasound is strongly dependent on the experience of the examiner. conservative as well as surgical management have good results, with good restitution to fine health of all patients. surgery seems to be only indicated when complications appear (homodynamic instability, severe pain, which cannot be managed conservatively). background. intestinal metaplasia (im) in specialized columnar lined epithelium in the distal esophagus is a precancerous lesion with a cancer risk of . % or case in patientyears. there are no prospective multicenter-data available for germany regarding the cancer-risk and also no data regarding different therapeutic treatment options. the purpose of this study was to evaluate the progression of dysplasia in barrett's esophagus (be) in patients under antireflux therapy -laparoscopic fundoplication (lf) or treatment with proton pump inhibitors (ppi) -based on the data of the german barrett esophagus registry. methods. in a consensus process a protocol was established by pathologists (n ¼ ), gastroenterologists (n ¼ ) and surgeons (n ¼ ). patient history, findings on endoscopy, histopathology and functional diagnostics were collected in a multicentric database. patients gave their informed consent for a central data registration. barrett's esophagus was defined as specialized, intestinal metaplasia in the endoscopic visible columnar lined epithelium of the esophagus independent of its length. the natural and posttherapeutic course of patients with im was registered prospectively. participating centres were free to decide for their own treatment approach for each patient regarding im as well as the underlying reflux disease. patients were followed with routine endoscopy and biopsy every - months. results. since january , patients with be were prospectively registered and analysed. of fourteen participating centres three were surgical (n ¼ ) and gastroenterological (n ¼ ). symptoms of reflux were present in % of patients daily or weekly, in % they were absent. the mean age of patients was years (range - ). two hundred and ninety six were male and female. three hundred and fifty patients ( %) had short-segment-be and ( %) long-segment-be. intraepithelial neoplasia was initially diagnosed in patients (low grade intraepithelial neoplasia (lgien) in , high grade intraepithelial neoplasia (hgien) in , indefinite in ). in the second histological confirmation hgien, lgien and indefinite ien were confirmed. in the other patients ien was excluded. from all patients ( insufficient and on competent lf) have shown progression from im to lgien and one from im to cancer (ppi) in a total of patient-years. conclusions. the current analysis shows a low rate of progression of im to ien for ppi treatment as well as antireflux surgery. this confirms recent reports on barrett's esophagus, that progression is a rather infrequent problem, which cannot be prevented by antireflux surgery or ppi. background. impaired esophageal motility plays an important role in the pathogenesis of gastroesophageal reflux disease (gerd) and its evaluation is important for the assessment of a therapeutic effect. the comparison of szintigraphic, manometric and symptomatic evaluation has not been shown yet. methods. sixty patients were evaluated with endoscopy, esophageal manometry, radionuclide scanning of esophageal emptying and assessment of symptoms prior to treatment (operation or medical therapy) and months later. in gerd patients with normal esophageal peristalsis the nissen fundoplication was performed, in further patients with impaired esophageal peristalsis a partial posterior fundoplication was chosen and further patients received continous medical treatment with ppi. all groups were comparable regarding age and gender of the patients. esophagitis was most pronounced in those patients who underwent partial posterior fundoplication. results. on endoscopy acute esophagitis resolved in all patients after fundoplication, whereas after months of medical therapy patients still had an acute esophagitis. on manometry there was a significant improvement of the competence of the lower esophageal sphincter postoperatively regardless of the performed technique. however, les relaxation was complete only after the toupet fundoplication but incomplete after the nissen fundoplication. esophageal peristalsis measured manometrically did not improve after medical therapy, was significantly strengthened after partial posterior fundoplication but was worsened by the nissen fundoplication. on szintigraphic evaluation of esophageal emptying for solid meals, there was no improvement after medical therapy but a significant improvement after partial posterior fundoplication. after the nissen fundoplication there was a significant deterioration of esophageal emptying. there was a strong correlation between szintigraphic and manomteric evaluation of peristalsis, preoperatively (rs ¼ À . p < . ) and postoperatively (rs ¼ À . p < . ). evaluation of symptoms showed no change regarding dysphagia after medical therapy and after the nissen fundoplication but a significant improvement after partial posterior fundoplica-tion. globus sensation was significantly improved after partial posterior fundoplication but did not change after medical therapy or the nissen fundoplication. postprandial bloating and inability to belch were significantly more common after the nissen than after partial posterior fundoplication. conclusions. antireflux surgery controls gerd better than medical therapy with ppis. however, partial posterior fundoplication is the more physiologic approach than the nissen fundoplication. background. combined impedance-and ph-monitoring (mii-ph) is a recently introduced diagnostic tool to assess gastro-esophageal reflux. we report our experience with this technology. methods. three hundred and fifty-seven mii-ph studies were performed in patients with clinical signs of gastroesophageal reflux disease (gerd) between may and december . a catheter was introduced into the esophagus via the nose and connected to a portable data logger. ph was monitored cm and impedance , , , , and cm above the manometrically located lower esophageal sphincter. symptoms were entered by the patients by pushing buttons on the data logger. diagnostic criteria for gerd were: pathologic acid exposure: ph < during > . % of total, > . % of upright, or > . % of recumbent recording time. pathologic impedance monitoring: > liquid or mixed liquid=gas refluxes detected by retrograde impedance drops > % from the baseline. positive symptom to reflux correlation: > % of > symptom events within a -minute time window after a reflux episode detected by mii-ph. results. three hundred and nine mii-ph procedures were performed after discontinuation of antisecretory medications for ! days in patients without prior esophageal or gastric surgery (age . ae . years). recording time was . ae . hours. the diagnostic yield of mii-ph is summarized in table . median total acid exposure was significantly higher in males than females ( . vs. . %; p < . ) as was the median number of reflux episodes detected by impedance ( vs. ; p < . ). the median number of symptoms was almost equal ( vs. ; n.s.). positive symptom correlation was significantly more frequent in females than males (p ¼ . ). the overall diagnostic yield of mii-ph was not significantly different between genders. conclusions. mii-ph is a valuable new tool for the diagnosis of gerd with significantly increased diagnostic yield over conventional ph-monitoring. acid exposure and the number of reflux episodes were significantly higher in male than female patients. sensitivity to reflux was significantly higher in females. diagnosis of gerd based on acid exposure alone lacks diagnostic sensitivity, especially in female patients. background. the surgical treatment is the most effective method for weight reduction in morbid obesity laparoscopic adjustable silicone gastric banding (lsgb) for morbid obesity has been reported to provide long term weight loss with a low risk of operative complications. nevertheless, esophageal dilation leading to achalasia-like and reflux symptoms is a feared complication of lasgb. patients undergoing obesity surgery were prospectively included in an observation study. this study evaluates the clinical benefit of routine preoperative esophageal manometry in predicting outcome after lasgb in morbid obese patients. methods. before surgery, each of the patients underwent pulmonary functional test, esophageal manometry and gastroscopy. drug medication and esophageal symptoms were recorded. a review of prospectively collected datas on patients (male , female ), who underwent esophageal manometry routine prior to lasgb for morbid obesity from january -december were performed. aberrant motility and other non specific esophageal motility disorders noted on preoperative esophageal manometry defined patients of the abnormal manometry group. outcome differences in weight loss, emesis, band complications were compared between patients of the abnormal and normal manometry groups after lsagb. results. of the patients tested had abnormal esophageal manometry results, whereas had normal manometry results before lsagb. there was no significant difference in wheight loss between the groups after gastric banding. severe postoperative emesis and achalasia like esophageal dilation occurred more frequently in patients with abnomal manometry results. band related complication were found in both groups. there was no difference in the prevalence of reflux symptoms or esophagitis before and after gb. the lower esophageal sphincter was unaffected by surgery, but contractions in the lower esophagus weakend after lsagb. conclusions. postoperative esophageal dysmotility and gastresophageal reflux are not uncommon after lsagb. preoperative testing should be done routinely. low amplitude of contraction in the lower esophagus and increased esophageal acid exposure should be regarded as contraindication to lsagb. patients with such findings should be offered an alternative procedure, such as laparoscopic sleeve gastrectomy or gastric bypass. background. laparoscopic implantation of an adjustable gastric band (agb) still represents the most frequently performed bariatric operation in austria. however, in recent years a general tendency to gastric bypass procedures can be observed. a mayor cause for this development may be long term problems such as the development of an esophageal dilatation. methods. from january until november , patients ( female, male) were treated with agb for morbid obesity at the krankenanstalt rudolfstiftung in vienna. adjustments of the band were performed under radiologic control weeks after the operation and on demand thereafter. of these patients, patients ( female, male, median age: years, range: - years), an equivalent of %, developed an esophageal dilatation during follow up. the median time from the operation to the occurrence of esophageal dilatation was months (range: - months). at the time of esophageal dilatation the median excess weight loss was % (range: - %), the median filling volume was ml (range: . - . ml). twelve patients had to be reoperated in a median of months (range: month- months) after the dilatation occurred. eleven patients had a gastric bypass operation after band explantation and one was converted into a sleeve gastrectomy. in the other patients a conservative approach has been persued so far, consisting of a deflation of the band and careful refillings after approximately month. eleven patients were already available for follow up a median of months (range: month- months) after the dilatation. ten patients significantly gained weight again. the median excess weight loss was reduced from % (range: - %) at the time of the dilatation to % (range: À - %) at follow up. only one patient managed to lose further weight without radiologic signs of esophageal dilatation after refilling of the band. conclusions. esophageal dilatation is a serious long term complication after agb which occurs approximately years after the operation and leads to a failure of this bariatric procedure in the majority of cases. further studies are needed to identify potential candidates for esophageal dilatation after agb. oversewing of gastric pull up staple line in reconstruction after esophageal resection: counterproductive or helpful procedure? considerable postoperative morbidity and mortality. recent studies have emphasized a notable improvement in morbidity rates at specialized centers. in our analysis we put special considerations on the need for an invaginatig suture of the mechanical staple line used for gastric tubulization. methods. between and , patients were treated for esophageal cancer by resection. perioperative data were collected prospectively. among those patients ( . %) underwent gastric pull-up reconstruction. the gastric tube has been constructed by gias using mm staple cartridges. these patients were included in the presented study. it was put upon the discretion of the treating surgeon, whether the staple line has been oversewn by an interrupted invaginating suture or not in a non-randomized manner. the main endpoint measure of the study is leak rate at the longitudinal staple line of the gastric tube without signs of major gastric ischemia. results. the mean age of the patients was . ae . years, . % of the patients were male. in = ( . %) patients an adenocarcinoma was diagnosed, whereas = ( . %) patients had a squamous cell carcinoma and = ( . %) were classified as others. in = ( . %) patients the gastric staple line was not oversewn (group a). in = ( . %) patients the gastric staple line has been reinforced by an invaginating interrupted suture (group b) . a leak at the staple line has to be reported in = ( . %) patients in group a, whereas no leak was seen in group b (p ¼ . ). two= patients ( . %, a: , b: ) experienced ischemic gastric tip necrosis. other surgical complications were anastomotic leakage ( = patients; . %; a: = , b: = ), temporary recurrent nerve injury ( = patients; . %; a: = , b: = ), anastomotic stenosis ( = patients; . %; a: = , b: = ) and chylus fistula ( = patients; . %; a: = , b: = ). conclusions. no significant difference was found between group a and b. however, all staple line leaks of the gastric tube developed, when the gastric tube staple line has not been oversewn. background. cardia carcinoma (ca) is characterized by different features compared with the remaining gastric ca; its incidence in western countries is increasing. the aim of the study was to investigate diagnostic, therapeutic and outcome measures of cardia ca in daily surgical practice. methods. all consecutive patients with cardia ca out of a pool of patients with histologically confirmed diagnosis of gastric ca who were treated in surgical departments were enrolled in this prospective observational multicenter study through a period of months. detailed patient, diagnostic and treatment characteristics were recorded in a computerbased format for analysis. short-term outcome was characterized by hospital stay, complication rate, morbidity and hospital mortality. results. from = - = = , . patients with gastric ca from surgical departments of each level of care were registered out of them subjects ( . %) with cardia ca. tumor localization was classified in patients according to siewert: typi, n ¼ ( . %); typii, n ¼ ( . %); typeiii, n ¼ ( . %). one hundred and seventy two patients underwent surgical intervention (operation rate, . %) of whom individuals underwent resection (rate, . %). a potentially curative resection could be offered to patients (r resection rate, . vs. . % in all gastric ca). fresh frozen section was only used in resections (rate, . %). of standard resections (distal esophagectomy with proximal or total gastrectomy), systematic d , d and d lymphadenectomy was performed in . , . and . %, respectively. histologic investigation revealed uicc stage i=ii in . % of all operated patients: iii=iv, %; not classified, . %. distant metastases occurred most frequently at the peritoneal site ( . %), liver ( . %) and non-regional lymph nodes ( . %). postoperative morbidity was . %. anastomotic leakage occured in patients ( . vs. . % in total of all gastrectomies in gastric ca) from whom subjects ( . %) underwent surgical reintervention. hospital mortality was . % (n ¼ ) compared to . % in all patients with gastric ca. conclusions. more than % of patients diagnosed with cardia ca show an advanced tumor stage at the time of surgical intervention. not all resections estimated as potentially curative were accompanied by d lymphadenectomy. in particular, to further improve hospital volume and r resection rate, to consequently use intraoperative fresh frozen section for the detection of an adequate tumor-free resection margin and to lower the rate of anastomotic insufficiency, it is suggested to treat patients with cardia ca at surgical centres for optimal outcome ( -year survival rate is being under investigation). deep brain stimulation therapy for psychiatric diseases g. m. friehs brown university, providence, usa background. obsessive-compulsive disorder (ocd) and major depressive disorder (mdd) causes tremendous suffering in those affected and in their families. neurosurgical lesioning procedures have been in existence for several decades and the overall reported success rate is widely quoted in the - % range. over the past years deep brain stimulation (dbs) has become available for a variety of conditions including ocd and mdd and has largely replaced lesoining procedure. methods. we report on our experience with patients with ocd ( ) and mdd ( ) treated with dbs of the anterior limb of the internal capsule (al-ic). patients who did not have multiple medication trials of adequate length and dose and trials of psychotherapy or behavioral therapy were excluded. also, mdd patients were required to have had a full course of electro-shock therapy (ect). patients were evaluated by a panel of independent psychiatrists before being referred for neurosurgery. all patients underwent a routine dbs surgery with implantation of bilateral electrodes into the al-ic. the stereotactic coordinates were - mm anterior to the anterior commissure (ac) and - mm lateral to anatomical midline, the electrode tip reached into the area of the nucleus accumbens. all patients had pre-and postoperative neuropsychology evaluations with testing batteries including the yale-brown-obsessive-compulsive-disorder scale (ybocs), global assessment of functioning scale (gaf) and hamilton-depression scale (ham-d) or the montgommery depression scale (mds). results. patients were followed for - months (average: . years), follow-up was complete for all patients ( %). = patients ( %) with ocd had improvements in their ybocs scores of more than % which was found to be significant (p < . ). also, these patients showed a significant (p < . ) improvement in their overall gaf. it was furthermore noted that the depression scores had a tendency towards improvement. of the five patients with mdd = patients ( %) had a significant improvement in their ham-d scores and gaf scores (p < . ). complications included one postoperative seizure, slight wound healing problems which did not require surgical intervention ( = , %). of note is the fact that the dbs batteries have to be changed very frequently (on average every - months). conclusions. dbs for ocd and mdd is a viable treatment for patients who have failed all other known therapeutic options. it is currently reserved for research centers who have a team of psychiatrists dedicated to the treatment of such patients. controlled studies will be necessary to develop guidelines for electrode placement and programming parameters. background. the number of patients demanding endoscopic neck surgery is rising. the access trauma of the axillary, breast and chest approaches is bigger than in open or video assisted surgery. we tested the feasibility of he sublingual transoral access which is in our opinion the only real minimally-invasive extracollar endoscopic access to the thyroid gland. methods. we performed an experimental investigation in a porcine model. in pigs we made endoscopic transoral thyroidectomys with a modified axilloscope with the help of ultrasonic scissors and a neuro-monitoring system for identification of the recurrent laryngeal nerve. results. the average operation time from the introduction to the removal of the obturator just above the larynx was seconds. the mean operation time was minutes. with the help of the neuro-monitoring system we proved in all cases the function of the recurrent laryngeal nerve on both sides. the pigs were observed for another two hours after operation. during and after the operation no complications appeared. conclusions. we could show that the endoscopic transoral thyroid resection in pigs is possible and save. our results might be useful for using this access for endoscopic thyroid resection in humans. background. actually, the surgical community receives some new impulses from interventionally orientated and skilled gastroenterologist by the so-called ''n.o.t.e.s.'' -natural orifice transluminal endoscopic surgery. this seems to be challenge enough to cooperate and contribute some surgically constructive ideas and critics. the surgical answer -with the intention to develop the arguments for a surgical engagement -to the presently still extra-clinical concept of ''notes'' may be given through an alternative procedure named ''flexible endoscopic minimally invasive transperitoneal'' (f.e.min.in. tra.p.) cholecystectomy. methods. after presentation of ''notes'', it's principles and aims, it's supporting societies and boards and their self-definition, a summary of already existing ''notes''-procedures and description of instrumental developments will be given. in contrast surgical considerations will be focused on more or less established surgical transluminal or even natural-orifice-transluminal techniques. in this context a special attention will be paid to surgical history and the life and times of e.mÜ he and the fact of a nearly-missed change of paradigms. as testimony for surgical endoscopic competence in interventional procedures the hybrid-model of f.e.min.in. tra.p. cholecystectomy will be opposed as surgical pendant to the conceptual idea of ''notes'' throughout a short clip-sequence. results. arguments for a surgical engagement in the development of ''notes'' are based on the following items: conclusions. only a close interdisciplinary cooperation may show weather the idea of ''notes'' will lead to clinical usefulness. it's invasivity as well as it's apparent strangeness to surgical behaviour and thinking should incline to an at least active interest. background. sacral nerve stimulation (sns) proves to be an effective therapy in patients with faecal incontinence. during the past years there were as well some promising results in the therapy of chronic obstipation. this study describes the experience with sns in patients with outlet obstruction. methods. four patients suffering of outlet-obstruction ( women), median age years (range - ) underwent test stimulation with a permanent electrode (tined lead). all patients had multiple previous conservative and operative unsuccessful therapy attempts. when complaints could be reduced by at least % with external stimulation, a permanent stimulator was implanted (two staged procedure). success of treatment was evaluated by: clinical examination, patient satisfaction (visual analogue score;vsa), cleveland-clinic-obstipation-score, and morbidity. evaluations were performed before start of treatment, before implantation and months after implantation. results. three of four patients completed the test stimulation stage successfully and received a permanent implant; median duration of stimulation stage was days (range - ). all these patients had a clear improvement according to their vas and cleveland-clinic obstipations-score. there was no postoperative morbidity. the median follow-up was months ( - ). conclusions. chronic obstipation can be treated successfully with chronic sacral nerve stimulation even after other therapeutic approaches have failed. however, this observation has to be confirmed in larger, controlled trials. background. the stapled transanal rectum resection (starr) is an accepted technique for the treatment of the obstructed defecation syndrome (ods). however, the technique with a circular stapling device (pph- ) is limited in large prolapse and the resection is performed ''blind''. a new device, the contour trans-starr (str g), has been designed with the aim of overcoming pitfalls of the current starr technique. this study describes the new technique and the initial experience in treating outlet obstruction or rectal prolapse. methods. all patients had multiple previous conservative or operative unsuccessful therapy attempts. the procedure was performed in lithotomy position and under spinal or general anaesthesia. the prolapse was sutured at the apex with the goal to obtain a uniform circumferential traction (parachute technique). then the new device was introduced into the rectum and a circumferential resection was performed step by step. success of treatment was evaluated by: clinical examination, ods-score, and morbidity. evaluations were performed before the treatment and months later. results. the study started in january and we estimate to enrol eight patients until the end of may . indications, patient's inclusion and exclusion criteria, morbidity and short term outcome will be discussed. conclusions. with the new device the starr procedure may become easier and more effective in the treatment of ods. however, safety and effectiveness has to be confirmed in larger, controlled trials. leber-gallengang therapeutic options for pyogenic liver abscesses h. cerwenka background. clinical management of pla (pyogenic liver abscess) has changed in the last decades due to constant improvements, for instance, in inventional radiology and antibiotic therapy. in surgical departments, we usually treat a selected group of patients with particularly severe forms. methods. our clinical study comprised a series of patients with pla. antibiotic treatment was modified according to sensitivity testing. additional therapy consisted of percutaneous puncture=drainage, endoscopic papillotomy=stenting and surgical interventions when indicated. results. fifty-eight patients ( %) had single and patients multiple pla. the disease was confined to the right hepatic lobe in % and to the left lobe in %; both lobes were affected in %. etiology was biliary in %, hematogenous in %, posttraumatic in % and cryptogenic or attributable to rare reasons in the remaining patients. microbiological culture was sterile in %, which was at least partly due to antibiotic pre-treatment. staphylococci, streptococci and e. coli were most often identified. anaerobes were found in %. factors associated with the need for surgery included: empyema of the gallbladder, underlying malignancy, perforation, multicentricity, vascular complications (hepatic artery thrombosis) and foreign bodies (e.g., toothpick, infected ventriculo-peritoneal shunt). in patients with biliary fistulae it was crucial to ensure prompt bile flow (for instance, by papillotomy=stenting). conclusions. assessment of underlying diseases is decisive for timely identification of patients requiring more invasive treatment. microbiological testing provides clinically important information for treatment monitoring and modification. special attention must be paid to diagnosis and treatment of concomitant biliary fistulae. therapy methods of hydatid disease from the tradition to the future m. sanal , h. guvenc , j. hager in europe. however there are some regions: upper bavaria, suedwuerttemberg (swabian alb), bathing (black forest), furthermore tirol, kaernten and steiermark, switzerland and north italy involved with this parasite. also people from turkey and the balkans bring the illnesses again and again. this lead to the necessity for physicians to be aware of its clinical features, diagnosis and management. methods. thirty patients with cyst echinococcus (ce) in liver, lung, kidney and spleen were in three different pediatric surgery departments innsbruck, bursa and kocaeli surgically treated. in the patients were cystotomy capitonage, simple cystotomy, unroofing, splenectomy, cyst excision performed. seven patients underwent minimal invasive surgery. results. postoperative bronchopleural fistula resolved spontaneously under negative pressure in five cases. the long-term postoperative results are considered good, with no recurrences observed. conclusions. surgery has remained the mainstay for the treatment of ce. the basic steps of the surgical procedures are eradication of the parasite by mechanical removal, sterilization of the cyst cavity by injection of a scolicidal agent, and protection of the surrounding tissues. pair technique in ce; performed using either ultrasound or ct guidance, involves aspiration of the contents via a special cannula, followed by injection of a scolicidal agent for at least minutes, and then reaspiration of the cystic contents. in the last years video assisted intervention has also been performed successfully. background. group milleri streptococci (gms), a heterogeneous group of streptococci, are associated with purulent infections. methods. retrospective analysis of all consecutive biliary infections due to gms in a four-years period. results. out of gms positive patients the innsbruck medical university within the study period, the biliary tract was affected in ( . %). the mean patient age was . ae . years, with a female:male ratio of : . . polymicrobial infections were present in . %. thirty percent of all patients were immuno-compromised after liver transplantation ( = ). seventy-nine patients ( . %) had clinical signs of infection, which was confined to the gallbladder in ( . %) (group i), while patients ( . %) presented with cholangitis (group ii). underlying diseases in the cholangitis group were biliary complications following liver transplantation in , other causes for mechanic cholestasis in , malignant intrahepatic disease in , ascending infections in and a ductus choledochus cyst in one patient. twenty patients ( . %) had gms positive bile cultures without clinical signs of infection (group iii) obtained during evaluation of cholestasis ( ), status post liver transplantation ( ), bilioma post liver resection ( ), and psc ( ). antibiotics were administered to patients ( . %) in group i, all patients ( . %) in group ii, and one patient ( . %) in group iii. in group i, all patients also underwent cholecystectomy. interventions were required in patients ( . %) in group ii (ercp ( ), external drainage ( ), surgery ( )), and patients ( . %) in group iii (ercp ( ), external drainage ( ), surgery ( )). gms isolates were susceptible to all penicillins, clindamycin and most cyclosporins, but were resistant to aminoglycosides and showed intermediate susceptability to ciprofloxacin. conclusions. the biliary tract was affected in one out of five patients with group milleri streptococci (gms). gms cause infection in % of all cases, and are often associated with mechanical cholestasis. background. peritonitis ossificans is a rare disorder with only few reported cases in literature. metaplastic bone formation in abdominal scars seems to be an own entity with only several descriptions mostly associated with trauma, gun shot wounds and repeated abdominal surgery. we report about a case with development of metaplastic bone formation and peritonitis ossificans after multiple acute surgical interventions. methods. chronological review of our patients medical history, pathohistological features and comparison of published data of ''peritonitis ossificans'' and ''metaplastic bone formation'' via pub med. results. our patient developed multiple nodular lesions with massive calcifications between the small bowel mesentery (heterotopic mesenteric ossification) after primary adhesive ileus and revision surgery because of colonic leakage. the situation developed within days from a prior abdominal situs without calcification. small bowel fistula occurred and we used abdominal vac therapy. ten weeks later partial secondary closure was performed and no sign of calcification could be observed. histological features showed fatty necrosis and scary tissue with metaplastic cartileage and bone tissue. literature is rare, pathophysiology, therapy and prognosis remains unclear. conclusions. male gender, multiple abdominal surgery or trauma with peritonitis, peritoneal dialysis and pancreatitis seem to be predisposing factors. extensive activation of myofibroblasts appears to be the major cause for hyperproliferation. the prognostic impact depends on secondary complications including postoperative fistula and leakage and intestinal obstructions. actually, literature shows no causative therapy. background. the differential diagnosis of dysphagia predominantly includes gerd, neoplasm, diverticula or achalasia. infrequent causes are diffuse esophageal spasm, scleroderma and other systemic diseases. eosinophilic esophagitis as a cause for dysphagia is found increasingly in recent literature and as a headline topic at congresses. methods. case report of a a old adipose male patient with multiple allergies who was suffering from dysphagia and bolus events for about years. they have been independent from pain, stress, temperature or consistency of food. gastroscopic examination showed a narrow esophagus with fragile, slightly corrugated mucosa. barium radiography and mri did not show any pathology. the patient underwent an esophageal manometry which showed a normal les with normal relaxation, but pressure peaks of mmhg on swallowing and % simultaneous waves. iced water or metoclopramide had no effect. ppi and nitro showed no improvement. sample biopsies of the whole upper gi during a second endoscopy revealed massive eosinophilic infiltration of the whole esophagus. results. the diagnosis eosinophilic esophagitis was herewith confirmed. the patient was treated with orally administered topic steroids (pulmicort spray bid orally for three months). his symptoms improved markedly. conclusions. eosinophilic esophagitis is an uncommon disorder. only publications with all over patients are published. male to female ratio is to . in % of the patients, food allergies can be found. peripheral eosinophilia can be detected in % and high ige in %. most of the patients are in the range of normal weight. the main symptoms are dysphagia in %, food impaction in % and heartburn in % of patients. endoscopically mucosal fragility can be detected in almost all patients, furthermore edema %, rings %, strictures %, corrugated esophagus, papules % and small caliber esophagus in %. eosinophilic infiltration ( =hpf) in the upper and lower esophagus without presence of eosinophils in the stomach or duodenum are detected histologically. the recommended therapy is oral administration of fluticasonpropionate or bethametason spray for two months. the initial response is about %, but relapse is common. systemic steroids are also effective. dilatation should not be performed because of a significantly elevated perforation risk and a high relapse rate. sample biopsies of the upper gi should be taken in every patient with unclear dysphagia since eosinophilic infiltration exclusively in the whole esophagus is pathognomonic for eosinophilic esophagitis and consequently dilatation should not be performed. p cholangiocellular carcinoma of the bile duct after resection of a congenital choledochal cysta rare manifestation background. the risk of malignant degeneration of a bile duct cyst is reduced by an early resection, but the risk of malignant change persists, as we show in our case. only few cases are published in the literature. as the prognose of a malignant degenerated choledochal cyst is very poor, the only useful possibility to minimize the risk of carcinoma is the early cystectomy. based on our case we like to discuss the indication for surgery, incidence of malignant change, risk factors, discovery and diagnosis, detection and prevention, the surgical procedures for the treatment of chledochal cysts and especially whether the typ of surgery have an impact on malignant transformation? methods. we report about a female patient who was examinated by ercp because of recurrent cholangitis. in her medical history we found out that on our patient a cholecystectomy has been carried out at the age of years and in addition to that procedure a congenital choledochal cyst typ i was resected, nevertheless the patient developed a massive cholangiocellular carcinoma which leaded to death at the age of years. after examination using multiphase ct we diagnosed a carcinoma to a great extent, which was inoperable. with the intention to obtain an operable condition, our patient was treated with neoadjuvant chemotherapy which remained unsuccessful. results. there are series of theories in the literature which try to explain the genesis of choledochal cysts, the real reason of their development is not clear, many possibilities for their emergence are discussed: i.e. weakness of the bile duct, distal obstruction, pancreatico-choledochal reflux caused by a long common channel, a wrong estuary of the pancreatic duct in the choledochus or also a pathologic distribution of ganglion cells on the wall of the choledochus. reviewing the worldliterature, the risk of degeneration of choledochal cysts is described differently, but the early resection is always recommended. conclusions. choledochal cysts are associated with an increase in the incidence of bile duct carcinoma. as it is shown, excision of a choledochal cyst is not protection by itself against the development of cancer in the future. after resection patients should have long term follow up. any patient, especially any adult, with recurrent symptoms following cyst related surgery must be evaluated for malignancies in the biliary tract. a surgical treatment after diagnosis of a choledochal cyst is necessary to avoid bile duct carcinoma. background. sporadic lymphangioleiomyomatosis (lam) is a nonmalignant proliferation of immature smooth muscle cells, usually in the lung but occasionally in the retroperitoneal lymph nodes as well. there is perilymphatic, perivascular and, with pulmonary manisfestation, peribrochiolar proliferation and invasion. it is an extremely rare disease (prevalence : ) that exclusively afflicts women of childbearing age. the most common presenting symptoms are dyspnea, cough, recurring pneumothorax or chylous ascites. the definitive diagnosis is obtained by biopsy. lam has a typical histological picture featuring diffuse, sometimes nodular proliferations of immature smooth muscle that stain specifically with the marker hmb- . unlike tuberous sclerosis (ts), sporadic lam is triggered by a mosaic mutation of the tsc- gene in the involved tissue. ts in contrast is caused by a somatic mutation of the tsc- gene. this somatic mutation leads above all to neurological symptoms (a trias of epilepsy, cognitive impairment, dermatological manifestations) but, in some cases, to a pulmonary manifestation of lam. at present, there is no curative treatment for lam, though a trial with gestagens is an option. terminal pulmonary failure is an indication for lung transplant. case report. in the course of a routine sonographic examination, a -year-old woman was found to have an expansive cystic process in the retroperitoneum. abdominal ct showed a pre-aortal lesion measuring .   cm with a partially cystic, partially soft-tissue structure suggestive of a cystic lymphoma or a cystic lymphangioma. the cyst was drained and partially resected laparoscopically. the histological diagnosis was lymphangioleiomyomatosis without indication of malignancy. preoperative chest x-ray and spirometry were within normal limits, but high-resolution thorax ct showed the cystic alterations typical for pulmonary lam. at present, the patient is free of complaints but due to the typical chronic course of the disease, close follow-up is indicated. conclusions. although it is a very rare disease, the diagnosis of a cystic retroperitoneal expansive process should suggest lam as a differential diagnosis. a definitive diagnosis can only be obtained with histology. because pulmonary involvement tends to be the rule, a thorax ct is indicated with primary abdominal manifestation. if there are neurological or dermatological manifestations, tuberous sclerosis should also be considered in the differential diagnosis. fetal mri: what is its worth outside the central-nervous system in extra-central-nervous system regions as it is mandatory in pediatric surgery. since fetal mri is performed at our institution, whenever a congenital malformation is suspected in the prenatal ultrasound. methods. fetal mri studies are performed on . t (philips) superconducting unit using a five-element surface phased-array coil, after th gestational week to avoid the possibility of magnetic fields interfering with organogenesis. no sedation is necessary. in addition to routine t -weighted (w) sequences, t -weighted sequences (mainly to demonstrate meconium-containing bowel loops), t -sequences (in case of hemorrhagic lesions), steady state fast precession (ssfp) sequences (to depict vessel-abnormalities), dynamic ssfp sequences to show swallowing and peristalsis, flair and diffusion-weighted sequences (for further tissue characterization) were performed. results. fetal mri is applied the following pediatric surgery cases: suspected lung anomalies ( cases), abdominal anomalies ( ), anal atresias ( ), esophageal atresias ( suspected), congenital diaphragmatic hernias (cdh) ( ), head-and-neck diseases ( ) and for urologic cases ( ). conclusions. detailed morphological description of congenital malformations is possible with fetal mri which may have a bearing on prognosis. it has become mandatory for antenatal counseling. in some findings such as esophageal atresia, gastroschisis or cdh an antenatal transport can be arranged to a perinatal center. background. in inflammation, activation of coagulation and inhibition of fibrinolysis lead to microvascular thrombosis. thus, clot stability might be a critical issue in the development of multiple organ dysfunction syndrome. activated fxiii (fxiiia) forms stable fibrin clots by covalently cross-linking fibrin monomers. in recent studies, multiple polymorphisms have been described in the fxiii-a subunit gene. the val leu polymorphism affects the function of fxiii by increasing the rate of fxiii activation by thrombin, which results in an increased and faster rate of fibrin stabilization. in the present study, we analysed the influence of the common fxiii val leu polymorphism on inflammatory and coagulation parameters in human experimental endotoxemia. methods. healthy volunteers received ng=kg endotoxin (lps, n ¼ ) as a bolus infusion over min. blood samples were collected by venipunctures into edta anticoagulated vacutainer tubes before lps infusion. for determination of the fibrinogen promoter polymorphism, we developed a new mutagenic separated polymerase chain reaction assay. results. fxiii levels were higher for homozygous carriers of the fxiii v l polymorphism in comparison to wild-typ and heterozygous. homozygous carriers had lower levels of tnf and il- in comparison to wild-type. interestingly, subjects homocygous for the fxiii v l polymorphism had lower monocyte and neutrophil levels throughout the timecourse. the fxiii v l genotype was not associated with clinically relevant differences in plasma d-dimer or f þ levels after lps challenge, which is consistent with the lack of effect on early thrombin generation. conclusions. our findings indicate, that the common fxiii v l polymorphism is associated with differences in the selected inflammation parameters and in monocyte and neutrophil cell counts in response to systemic lps infusion in humans. those findings may have an impact on clinical treatment for patients with inflammatory diseases. p stamm-kader gastrostomy or peg w. h. weissenhofer time-honoured or forgotten? the stamm-kader gastrostomy, introducing a nelaton catheter via a stab incision through the upper abdominal wall, guided by direct vision after laparotomy or using a minilaparotomy or even by laparoscopy can be considered an easy alternative to the widely used peg or similar endoscopic procedures. the ''old'' and simple stamm-kader procedure offers not only direct vision, possibilities of local anaesthesia and a minimum of instruments and therefore costeffectiveness, but is also a welcomed addition to the surgical armamentarium -once learned. the actual procedure includes an abdominal accesswhether minimal or already present in case of operations for bowel obstruction, further a double pursestrig suture between large and small curvature of the stomach, stab incision and introduction of a large lumen balloon catheter, the double pursestring sutures are tied in such a way that a short channel in the stomach wall is formed and then covering sutures between abdominal wall and stomach are tied. the catheter can be used immediately for decompression and early feeding. obviously this is a surgical method and has therefore a much smaller following and tends to be forgotten as there are no ''progressive'' endoscopic devices to be advertised and there is minimal economic interest to be generated for medical companies. nonetheless it is in my opinion and experience an useful route in more ways than the peg or button gastrostomies can ever offer. the blood levels of c-reactive protein (crp), interleukin (il) , , and icam- were measured using the elisa technique in all patient before, immediately after operation, at the first and third day after surgery. the pre-operations levels of crp and all mediators had no differences in both group of patients. significant increase of il- , il- and icam- level was noted in the first group vs. insignificant changes of mediators' levels in patients of the laparoscopic group immediately after operation. the gradually increase of all mediators' plasma levels were noted in first group up to the third day after operation. crp was peaked at the third day in both group, but the increase after open adrenalectomy was more pronounced (p < . ). levels of il- and icam- had strong correlation with the hematological changes that observed in the postoperative period. the cytokines play a pivotal role in the orchestration of the immune response. the increased levels of il- and il- pointed on enhance of th response. activation of th cytokines may provoke the immunosuppression and the catabolic stage and may have adverse consequences for patient recovery. thus, there is a clear correlation between the changes in cytokine levels and the degree of surgical trauma. methods. combined retroperitoneal pancreas-kidney transplantation was performed in a -year-old patient with type-idiabetes and diabetic nephropathy. the patient had a bmi of and had undergone renal transplantation in the right iliac fossa years ago. after mobilization of the colon and mesocolon ascendens, the graft was anastomosed end-to-side to the aorta and to the inferior caval vein. the graft was in a retroperitoneal position. for exocrine drainage a side-to-side duodenojejunostomy was performed after bringing a jejunal loop through a window in the colon mesentery. results. the anastomoses could be performed with ease. duration of the pancreas implantation was minutes, minutes for implantation of the kidney in the left iliac fossa. ischemic time was hours. a revision was necessary due to obstruction of the graft ureter. from day after transplantation the patient required no more insulin, and lipase and amylase levels were within the normal range. conclusions. the first experience with retroperitoneal pancreas transplantation with systemic-enteric drainage showed, that the technique was safe, and had technical advantages as compared with the classic method. it should be especially applied in high risk patients (obesity, severe atherosclerosis). background. recell + is a new medical product for yielding a cell suspension of the skin. in this process cells are removed from the basal layer of a thin split skin graft. the removal of the skin graft, the preparation of the cell suspension and the covering of the defect can be done in one treatment session in the operating theatre. recell + could be used for the coverage of superficial defects in burns, scars, skin resurfacing and vitiligo. the advantages of this new technique are a shorter healing period, better scar quality and the ability of repigmentation. methods. for yielding cell suspension, which is quickly available, a thin split skin graft (thickness . - . mm) is taken. depending on the defect, the size of the split skin biopsie is from  cm for coverage of cm to  cm for coverage of cm treatment area. after separation of the different layers of the skin, the special cell suspension could be prepared. then the cell suspension is immediately sprayed or trickled on the prepared wound area. a special laboratory is not required. the first change of the wound dressing is done week postoperatively. conclusions. the result of this new treatment option is a skin of good quality, colour and function -comparable with the original skin. the first experiences show recell + as an interesting amendment to the previous therapeutical options. however, other studies should be done to fathom the spectrum of the indications and to confirm the first results. p early experience with ductoscopy guided minimal invasive surgery for intraductal breast lesions c. tausch, p. schrenk, e. grafinger-witt, t. gitter, s. wölfl, s. bogner, w. wayand background. intraductal breast lesions which have been diagnosed by radiological ductography are sent to breast surgery. by a cirumareolar incision a poorly defined extent of tissue will be removed. it can be supported by presentation of the main duct by injection of blue dye. taking into consideration that papillomas are benign in - %, it is worthful to minimize the extent of the intervention. this fact and the aim to visualize the origin of most types of breast cancer -the terminal ductolobular unit (tdlu) -induced the development of endoscopes for the milk ducts. methods. after canulating the ductus lactiferous it will be distended by a special dilatator. the endoscope (laduskop + , polydiagnost comp.) is inserted through this dilatator and the inspection of the ductal system is possible til over the fourth bifurcation. endosopes are available with device for flushing and working ducts for biopsies. results. this a first report about the experience with ductoscopy in patients presented with unilateral secretory disease. after successful localisation of an intraductal leason a tissue sparing excision of the affected duct follows guided by the in situ lying ductoscope. conclusions. endoscopy of the mammary duct system is a precious diagnostic tool for onesided secretory disease und is able to minimize the extent of the removed tissue. the role of the method in the perioperative visualisation of intraductal diessemination of breast malignancies needs further evaluation. p ruptured aneurysma of arteria lienalis with massive bleeding because of fibromuscular dysplasia background. fibromuscular dysplasia (fmd), a non-ather-osclerotic=non-inflammatory vascular disease, is a rare cause of visceral artery aneurysmas (vaa). in about % of all cases, vaa presents first with rupture and leads to a overall-mortality of . %. about % of fmd are familial, most likely in female and often as multifocal lesions. patient's history. a years old female patient was admitted to our department with nausea and epigastric pain. former history showed an aneurysma of the iliacal artery treated by iliacofemoral bypass (pathohistological examination of the aneurysma showed fmd), and several episodes of spontaneous subcutaneous haematomas. abdominal ultrasound, x-ray and gastroscopy showed no abnormalities. moderate anaemia without any sign of gastrointestinal bleeding made us perform a ct-scan which showed an intraabdominal and peripancreatic haematoma without any sign of a recurrent aneurysma. under icu-monitoring the patient showed another episode of acute epigastric pain and developed signs of haemorrhagic shock. we performed an acute median laparotomy and found no cause of intraabdominal bleeding. exploration of the peripancreatic haematoma showed the cause of bleeding as a ruptured aneurysma of the central splenic artery. resection of the aneurysma and splenectomy had to be performed. the patient was discharged from the hospital on the th postoperative day. conclusions. ruptured vaa caused by fmd as rare reasons for acute abdominal pain need most aggressive treatment to avoid postoperative mortality. background. today, iatrogenic injuries are the most common cause of hemobilia. the hepatobiliary system is at risk for damage as side effect from procedures such as percutaneous bile drains and liver biopsies. complications of open and laparoscopic surgical procedures can also be responsible for hemobilia. methods. we report of a rare case of iatrogenic hemobilia occurring after laparoscopic cholecystectomy. results. a -year-old patient was readmitted to our department, days after laparoscopic cholecystectomy, complaining about upper abdominal pain and presenting with signs of jaundice (bi ¼ . mg=dl but ap ¼ u=l) and anaemia (hb ¼ . g=dl). the patient, who was a jehovah's witness, refused blood transfusions. on readmission ercp demonstrated fresh active bleeding from the papilla of vater. cholangiography demonstrated obstruction of the common bile duct by intraluminal blood clots. blood clots were retrieved by means of an endoscopic ballon-catheter. ct scan and angiography showed a . cm contrast retaining pseudoaneurysm in the hilus of the liver oroginating from the stump of the cystic duct. interventional radiological selective stenting of the hepatic artery could not be performed for technical reasons. the patient was re-operated, the site of bleeding was identified as the cystic artery stump and surgically controlled with sutures. the patient's further postoperative course was uneventful with quick recovery and without the need for blood transfusion. conclusions. hemobilia is a rare complication after cholecystectomy, which may stem from a pseudoaneurysm of damaged vessels, e.g., the stump of the cystic artery. when management by interventional radiology fails, surgical intervention is mandatory. background. we describe on of the rare cases with a perforated barrett-ulcer resulting in an esophagopleural fistula. the importance of recognizing esophageal disorders and catastrophes in the management of acute abdominal emergencies is emphasized. methods. chronological review of our patients medical history, pathohistological features and comparison of published data of ''esophageal perforation'' via pub med. results. a young, male, alcohol-addict patient presented to the emergency department after a fall over staircase with serial rips-fracture and only little discomfort. chest x-ray and blood sample were inconspicuous. on the following day patients general condition got worse, a pneumothorax occurred. so it was necessary to install a bulau drainage which encouraged food out of the left pleuracave -therefore an ''esophageal perforation'' was supposed. the patient was transferred, now with a mediastinial sepsis and multi organ-failure, to our medical surgery unit, where primarily a esophageal stent and a thoracotomy with cleansing and drainage of the mediastinum and the pleural cavity was set. but within a week the stent became insufficient and an esophagectomy and a gastrostomy were necessary. after weeks therapy on the intensive care unit, the patient underwent again a thoracotomy with decortication of a pleura callositiy because of the persistence of a fluidopneumothorax. the patient is now disposed to a colon interposition. conclusions. possible risk factors for perforation in general and in this patient included alcoholism, severe gastroesophageal reflux, noncompliance with antacid and ppi blocker therapy and the presence of acid-secreting parietal cells in the barrett's epithelium. misdiagnosis is the most important contributing factor in the continuing high morbidity and mortality of esophageal-perforation as shown by all reported cases. background. the use of ergotamine, e.g., suppositories for migraine headaches, may have systemic as well as local side effects. systemic poisoning is known as ergotism, historically mostly due to the ingestion of rye infected with claviceps purpura fungi. local complications, like rectal ulcers and rectovaginal fistula may require surgical management. methods. we report about the case of a year old female patient with deep anal necrosis, insufficiency of the anal sphincter, anovaginal cloaca and rectal prolapse, as long-term sequelae of ergotamin suppository application. results. the patient was hospitalized for treatment of the rectal syndrome mentioned above. the anoderm appeared completely destroyed, with extensive scarring and manifestation of an anaovaginal cloaca. anal manometry showed almost no anal pressure. anal sonography demonstrated an anterior semicircular defect of the internal as well as the external anal muscles. the patient had already been seen in our hospital two years previously, when a perineal necrosis had raised suspicion of a locally advanced anal cancer. that time, she had refused to undergo further diagnostic work-up (including re-biopsy, etc.) and treatment, after endosonography had suggested an infiltrative process affecting the anal sphincter and the histopathologic diagnosis spoke of a ''tumor necrosis . . . but without viable tumor cells''. now, after exclusion of a neoplastic process, the patient underwent a complex surgical procedure for management of her incontinence syndrome: a laparoscopic resection of the rectum and rectopexy was performed. furthermore sphincter and perineum were reconstructed using an anterior levator plasty and ventral sphincter-overlapping repair. a temporary protective loop ileostomy was created in addition. conclusions. this case describes the -to our knowledgemost extensive local complication due to ergotamine suppositories, in the world literature. it suggests that ergotamine suppositories should be used with precaution, and a close followup by the prescribing practitioner is mandatory. furthermore, patients with unclear inflammatory destructive alterations of the perineum and unexplained rectal syndrome should be asked for ergotamine suppository (ab)use. p intrapancreatic accessory spleen: a differential diagnosis of pancreatic tumour background. according to autoptic studies, accessory spleens may be found in to % of the population and most of them are usually located at or near the splenic hilum. only in to % they are located in the pancreatic tail. we report a rare case of intrapancreatic accessory spleen which radiologically mimicked a tumor in the tail of the pancreas. methods. a -year-old man was diagnosed with a tumor at the pancreatic tail. in the preoperative computed tomography (ct), there was a lesion ( . cm in diameter) in the pancreatic tail and two locoregional lesions ( . and . cm in diameter), which had intensive contrast enhancement. it was diagnosed as a nonfunctioning endocrine pancreatic tail carcinoma with lymph node metastasis. results. intraoperative examination showed two accessory spleens nearby the pancreatic tail. as pancreatic cancer could not be excluded because of the local findings, an oncological left pancreatectomy was performed. histological examination excluded cancer and revealed an intrapancreatic accessory spleen and two accessory spleens nearby the pancreatic tail. conclusions. intrapancreatic accessory spleen should be included in the differential diagnosis of pancreatic neoplasm. a useful diagnostic tool is scintigraphy with technetium- marked, heat shock denaturated autologous erythrocytes. background. sacral nerve stimulation (sns) is a widely accepted therapeutic options for patients suffering from faecal incontinence based on a neurogenic dysfunction. more recently case reports have been published showing a positive effect of this treatment in patients suffering from faecal incontinence after low anterior rectal resection. the purpose of this study was to perform a nationwide survey for this selected indication for sns in order to gain more information by recruiting a larger number of patients. methods. in the period to three austrian departments reported data of patients who underwent sns for faecal incontinence following rectal resection. data were available of patients ( females, males) with a median age of years (min -max ). six patients had undergone rectal resection as a treatment for low rectal cancer. one patient had undergone rectal resection for crohn's disease, one patient subtotal colectomy and ileorectostomy for slow colon transit constipation. results. in all patients test stimulation was performed in the foramen s unilaterally over a median period of days ( - d) . seven patients reported a marked reduction of incontinence in the observation period. five patients reported a marked improvement compared to the baseline of their continence situation. three patients had no further incontinence episodes following the permanent implant. two patients reported ''rare events'' ( - incontinence episodes= month). one patient who had previously reported an improvement of his continence function during his test stimulation complained about repeated urgency problems as well as incontinence episodes. conclusions. despite our observations and the promising results of others the role of sns in the treatment of faecal incontinence following rectal resection needs further research as well as more clinical data by a larger number of patients. p lymphatic vessel invasion in upper gi cancer: an indication for an additive or adjuvant therapy? and ac had significant lower lvi-rates compared to nonresponders. these data warrant prospective data and might result in the future into an additive or adjuvant multimodal therapy. [up to now = recurrencies ( . %) were seen.] all patient data were collected prospectively. in the present study we compared all patients with an operations time of minutes or more with those with operation times < minutes and compared patient related factors (asa, bmi, type of hernia, recurrent hernia, scrotal hernia, incarcerated hernia and situs-related problems) and operation related factors (surgeon's experience, intraoperative problems, anaesthesiologic problems). results. mean operation time was . ae . minutes. operation time did not increase with asa and bmi (pearson coefficient . resp . ). direct hernia were faster operated than indirect, combined or recurrent hernias in total (average time . ae . ; . ae . ; . ae . ; . ae . ). the proportion of recurrent ( . %) and scrotal hernia ( . %) in operations longer than minutes was significantly higher (n.s. resp. p < . ), in incarcerated hernia ( . %)and hernias with long anamnesis and difficult scarred situs ( . %) or combined with additional operations ( . %) as well. in operation related factors individual designed ring-armed patches demanded - minutes more operation time and thus clearly prolonged the operation (p < . ), unexpected intraoperative problems (e.g. in positioning the patch) or complication (bladder injury) as well. in rare cases anaesthesiological problems (insufficient spa) caused delay as well. most important seems to be surgeon's experience. with increasing experience the average operation time and the proportion of long lasting operations decrease. conclusions. while patient's asa and bmi do not influence the tipp operation significantly, hernia type, recurrency, incarceration and scrotal hernia resp scared situs influence the operation clearly. in operation related factors surgeon's experience seems to be most important, intraoperative problems or complications result in an unexpected delay as well. in preoperative planning knowledge of recurrency (previous operation method), scrotal hernia or incarceration or scar-inducing anamnestic factors give hints to a prolonged hernioplasty. p biomechanical analysis of the ventral abdominal wall for incisional hernias c. hollinsky, c. yiwei, j. ott, s. sandberg, m. hermann background. for the therapy of ventral abdominal wall hernias, different reinforcement techniques with mesh are available. nevertheless the outcome of treatment for ventral abdominal wall hernias is currently unsatisfactory. biomechanical load flow calculations are introduced in this study. methods. we took peritoneum and abdominal wall muscles of recently deceased cadavers to determine the friction coefficient for mesh protheses. therefore we placed the mesh between peritoneum and muscles and loaded them with tension. furthermore we analyzed the different fixation elements for their load resisting capacity. results. the prostheses demonstrated a frictional coefficient of m ¼ . . the elasticity module e of polypropylene is ¼ n=cm . for laparoscopic techniques, leight meshes showed an unproportional high bending and sheared off at low loads. for the reinforcement elements, large differences between different tensile load capacities were detected. conclusions. the overlap of the protheses over the hernia orifice should be selected proportionally to the hernia size. light meshes are unfit for the laparoscopic techniques and should not be used for the therapy of ventral wall hernias. p the axillary access in unilateral thyroid resection k. witzel ; universitätsklinik für chirurgie, salzburg, austria; the new european surgical academy (nesa), berlin, germany background. with this study, we intended to find out if it is possible to avoid the typical scar after thyroid resection by using a mm axillary access and a . mm incision in the jugulum. methods. we present the results of our proof-of-concept study with patients. for this technique, a modified axilloscope and ultrasonic scissors were used, which permit a total resection of the unilateral thyroid. results. the feasibility of this endoscopic technique was shown by the successful operation of these patients with uni-lateral pathological findings. furthermore, we showed that this technique allows to resect tissue up to a whole lobe while at the same time finding and identifying the recurrent laryngeal nerve and subsequently verifying the findings by using the neuromonitoring system. conclusions. this study shows that endoscopic thyroid surgery approximates the norms of endocrine neck surgery. the presented method is useful in thyroid surgery for patients with single nodules and a small thyroid gland. background. ventral incisional hernias have a high incidence after laparotomy closure. laparoscopic hernia repair is a minimal invasive technique with less operative trauma. the aim was to assess the reccurence rate and morbidity after the laparoscopic repair. methods. data of all patients with laparoscopic incisional hernia repair operated in our department between december and november were recorded in a prospective data base. forty two patients (m:f ¼ : ) with a mean age of years ( - ) and a mean bmi of kg=m ( - ) were operated. results. conversion rate was % due to intraoperative lesions to small bowel during adhesiolysis. mean operation time was min ( - ). in patients the dual-mesh, in patients the bard composite ex mesh and in patients the parietex mesh was implanted. mean hospital stay was days ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) . the morbidity-rate was . % ( hematomas) . four patients complained about prolonged pain. in the long term follow up patient had to be reoperated due to mesh related complications. mean follow up time was months, patients presented with a recidive hernia. conclusions. laparoscopic ventral hernia repair can be performed with acceptable recurrence rate ( . %) and low morbidity ( . %) independent of the used mesh. p outcome of clip removal after endoscopic sympathetic block anecdotal reports are available on clinical outcomes after cr. the aim of the study was to investigate whether cr actually resulted in reversal of compensatory sweating (cs), and whether the initially obtained therapeutic effect on hyperhidrosis of the upper limbs (hh) and the face (fh) and facial blushing (fb) diminished with time. methods. between = and = a total of patients ( females, males) with a mean age of ae years underwent cr after esb. three patients underwent unilateral clip removal due to mild ptosis (one patient with esb , patients with esb ). twenty patients had their clips removed due to unbearable cs. levels of hh, fh, fb and cs were graded by a visual analogue scale ranging from (no sweating= blushing) to (most severe sweating=blushing). mean followup after cr was ae months obtainable from patients ( %). results. the patients who suffered from ptosis started to improve weeks after cr, complete relief was observed months thereafter. in each group with esb and esb , . % of patients underwent cr. only one patient after esb had to be reoperated ( . %, p < . compared to esb and esb ). four patients ( %) reported no change in cs after cr, in patients ( %) cs dissolved completely. overall, cs improved from . ae . to . ae . (p < . ). hh, fh and fb recurred to about % of the initial levels, patients ( %) reached preoperative levels. conclusions. clip removal because of unwanted side effects is more common in patients after esb and esb than after esb . cr results in partial reversibility of cs and causes partial recurrence of the initial complaints. although some patients do not benefit from cr, our study provides valid data that esb is a reversible technique. p acute reinterventions following laparoscopic transabdominal preperitoneal inguinal hernia repairs (tapp) b. walzel, p. patri, p. razek, a. tuchmann background. today the tapp method is a frequently used surgical procedure for treating inguinal hernia. although this type of operation has some advantages compared to open procedures, some complications typical for laparascopy might arise. we report about managing such complications as based on our experience. methods. between january and december tapp was applied in our hospital to (n ¼ ) patients. from among those patients (n ¼ ), ( m, aged - ) laparoscopy had to be repeated because of acute complications which occurred between the st and th postoperative day. three patients presented post op a bilateral tapp. reasons for interventions were: obstruction of the small intestine due to incarceration with a dehiscent peritoneal suture (n ¼ ), hematoma in the area of surgery applied (n ¼ ) and one hemorrhage caused by a trocar (n ¼ ). in three patients (n ¼ ) with a mechanical obstruction of the small intestine, repositioning by laparoscopy of the incarcerated ileus was carried out, followed by a peritoneal suture. in two cases with intraabdominal hemorrhage, the bleeding was stopped and the prolene nets were removed via laparoscopy. in only one of the cases replacement of the net was possible, in the other one the procedure was changed to open surgery for inguinal hernia because of an infected net. in one patient (n ¼ ) hemorrhage due to injury by trocar repair was possible by a simple suture. results. in out of cases the complication was successfully repaired by way of laparoscopy. in one case the shouldice repair was applied. in the other a paralysis of the ileus occurred post laparoscopy, requring a smoothing of the ileus by laparotomy. conclusions. among our patients severe complications following tapp needing surgical intervention occurred but rarely ( . %). frequently treatment by way of laparoscopy was successful. p clip displacement does not effect postoperative outcome after endoscopic sympathetic block p. t. panhofer , c. neumayer , s. nemec , r. jakesz , g. bischof , j. zacherl background. endoscopic thoracic sympathectomy is the treatment of choice for patients with severe primary hyperhidrosis (hh). recently, clip application (endoscopic sympathetic block, esb) has been introduced providing potential reversibility. the clips are visible on x-rays allowing postoperative evaluation. at our institution ganglion oriented procedures are performed taking rib levels into account. the aim of the study was to investigate if failures, recurrences and unwanted sideeffects (compensatory sweating, cs) can be explained by clip displacement. methods. between and , patients (mean age . ae . years) prospectively underwent esb procedures. esb was performed in patients ( . %) with facial blushing (fb), esb in patients ( . %) with facial sweating (fs) and esb in patients ( . %) with hh of the upper extremities following the lin-telaranta scheme. a mm titan clip was placed above and below the corresponding ganglion. two quality of life scores have been evaluated. mean follow up was . ae . months obtainable from patients ( . %). results. ninety-eight patients ( . %) had palmar, ( . %) axillary hh, ( . %) fs and patients ( . %) fb. cs was observed in ( . %) patients. a total of clips ( . %) were displaced in patients ( . %). two patients with fs ( . %) and with hh of the upper extremities ( . %) showed up with side differences regarding placement. in each group, one single patient was found with clips one level below the expected destination ( patients, . %). four patients ( . %) were completely and patients ( . %) partly satisfied after esb despite displaced clips. two patients have been lost to follow-up. moderate cs was observed in one patient ( . %) in each of the fb and fs groups. the patient from the latter group suffered from a mild transient ptosis additionally. two recurrences ( . %) were documented. methods. blood samples were collected from patients before major surgery. whole blood was incubated with escherichia coli lipopolysaccharide (lps) and il- production in supernatants was assessed by enzyme-linked immunosorbent assay. the prognostic impact of ability to synthesize il- before surgery was investigated in patient subgroups with respect to sepsis-related mortality using multivariate binary logistic regression analysis. results. il- synthesizing capability in patients who survived sepsis was significantly higher than that in patients who developed fatal sepsis (p ¼ . ). in multivariate analysis only il- was associated with a lethal outcome from postoperative sepsis (p ¼ . ). the prognostic impact of il- was evident in patients with underlying malignancy (p ¼ . ) and in those who had undergone neoadjuvant tumour treatment (p ¼ . ). when patients were analysed according to the type of neoadjuvant therapy, preoperative ability to synthesize il- had a significant prognostic impact in patients who had neoadjuvant radiochemotherapy (p ¼ . ), but not in those who had neoadjuvant chemotherapy. conclusions. il- production after stimulation of whole blood with lps appears to be useful for the preoperative assessment of risk of sepsis-related death after operation in patients who have undergone neoadjuvant radiochemotherapy. p lipocalin- , regulator or byproduct during ischemia and reperfusion? background. the main focus of this work was to analyze the possible implication of lipocalin- (lcn- ) upregulation for the course of ischemia=reperfusion (ir) during heart transplantation and effects on polymorphonuclear cells (pmn) as well as to investigate the nature of the lcn- producing cell. methods. male inbred c bl= and the lcn- À=À mouse were used in our transplantation experiments. pmn from wildtype and lcn- À=À mice as were isolated and promyeloid cell lines ( d) used to demonstrate the effect of lcn- on cell physiology. western blot, rt-pcr, immunohistochemistry and tunel assay were performed to determine lcn- expression and apoptosis in the graft. cell viability and migration assays after various stimuli (e.g. ir) were applied to elucidate cell growth and viability. results. infiltrating pmn were the major contributors to lcn- expression during ir peaking h after reperfusion. the number of infiltrating pmn was significantly reduced in lcn- À=À recipients. no difference was observed in the apoptotic rate between wildtype and lcn- À=À donors and lcn- expression also increased during acute graft rejection. migration of pmn during reperfusion was negatively influenced by the absence of lcn- or lack of lcn- specific cell surface receptors in the lcn- À=À mice. the promyeloid cell lines responded to ir with increased lcn- mrna and protein levels. conclusions. our data suggest a chemoattractant function of increased lcn- expression in the transplanted heart due to infiltrating pmn. lcn- is a novel inflammatory marker upregulated during ir and acute graft rejection. our observations shed light on a possible function of lcn- to the recruitment of pmn to the site of ir and identify possible targets for therapeutic intervention. p preliminary results of a tumour-lysate loaded dendritic cell vaccination therapy in patients with recurrent or metastatic skeletal malignancies p. t. background. vaccination with tumour-lysate loaded dendritic cells (dc) has shown to modulate potent immune response in several animal models and clinical trials. this study presents preliminary data of patients treated with dc-vaccination for recurrent or metastatic skeletal malignancies. methods. in patients suffering recurrent chondrosarcoma ( ), haemangio-endothelioma ( ), ewing's sarcoma ( ), osteosarcoma ( ), or osseous metastatic disease of renal cell carcinoma ( ) dc-vaccination was applied additional to standard therapy such as surgery and=or chemotherapy and=or radiation. dc precursor cells were obtained from peripheral blood mononuclear cells by apheresis and incubated with autologuous tumor cell lysate gained by surgery. in each patient vaccinations of  e cells ( ¼ . ml) were administered intranodally under sonographic guidance in weekly intervals. delayed type hypersensitivity (dth) controls and standard clinical and radiological follow-up was performed before and after treatment. results. no adverse or side effects were observed in any patient throughout treatment. dth reaction was negative in all patients after therapy. six patients died of disease, patients showed progressive state of disease in terms of local recurrence or pulmonary metastasis, revealed stable disease. helper as well as cytotoxic t-lymphocytes of patients showed in vitro reactivity in terms of cd expression against tumour antigens and against the tracer antigen klh by both cd and cd expression. one patient had no increase of cd and cd expression neither against tumour nor tracer antigen, one patient showed positive immunological reaction against klh but not tumour. conclusions. in all patients with recurrent or metastatic skeletal malignancies investigated in this study dc vaccine therapy was primarily administered at very late stage of disease. the best clinical results could be achieved in patients with metastases of renal cell carcinoma, who both revealed stable disease over more than months. all patients with metastatic disease of recurrent sarcoma showed poor clinical response to therapy, though some showed immunological reaction. the absence of adverse reactions and uncomplicated therapeutic regimen, however, together with monitored immunological responses suggest that the effects of dc-vaccination should be investigated in earlier stages of sarcoma to improve clinical outcome in these patients as well as in all stages of metastatic disease of renal cell carcinoma. p analysis of the risk factors helicobacter infection, overweight, sex, and age in gallstone disease and gallbladder carcinoma in germany background. helicobacter infection of the hepatobiliary system has been proposed as a novel risk factor in the pathogenesis of gallstone disease (gsd) and gallbladder carcinoma (gbc). because there seem to be differences in the incidences of helicobacter infection in various populations, we investigated whether helicobacter infection of the biliary tract is present in germany, a region with a high incidence of gsd, but with a low incidence of gbc. methods. gallbladder tissue from patients who had undergone cholecystectomy were investigated: patients with gsd, cases with gbc, and control patients. the presence of helicobacter spp. was investigated by culture, immunohistochemistry, and a group-specific pcr targeting the s rrna and detecting all currently known helicobacteraceae. results. of the cases investigated, only one patient with gsd was pcr-positive for helicobacteraceae. in this subject, sequence analysis of the s rrna showed closest homology to the s rrna sequence of h. ganmani. helicobacteraceae were not detected by culture or immunohistochemistry. there was a higher body mass index in patients with gsd compared to controls (p < . ). mean age of patients with gbc was significant higher than for gsd (p < . ) or control patients (p < . ), whereas there was no difference between gsd and controls. conclusions. these data suggest that helicobacteraceae play no predominant role in the pathogenesis of gsd and gbc in the german population. the low prevalence of helicobacteraceae in the gallbladder mucosa of german patients could be a possible explanation for the relatively low prevalence of gbc although gsd is frequent. background. apoptosis is implemented in colorectal cancer (crc) development and has emerged as a potential target for cancer treatment at various stages of tumor progression. measurement of the apoptosis (m )=necrosis (m ) ratio may have a role in therapy monitoring. to define the value of preoperative assessment of apoptosis and necrosis we measured these parameters in the sera of crc patients and correlated these values with conventional clinical parameters. methods. we used an enzyme linked immunosorbent assay (elisa) to detect an apoptotic product and necrosis (m and m -antigen) in the sera of patients with crc; uicc i: n: ; uicc ii: n: , uicc iii: n: ; uicc iv: n: ; relapse: n: and healthy controls. results. patients with colorectal cancer showed significant higher m antigen levels than healthy controls (p < . ). when stratified to tumor stages the different preoperative m antigen expressions between healthy controls and tumor patients remained throughout all stages. detailed results are depicted in the following table: m results and the clinical applicability of the m =m ratio are under investigation and will be presented at the meeting. conclusions. levels of circulating m -antigen are increased in patients with colorectal cancer. clinical follow up studies will reveal the usefulness of a ratio value of apoptosis and necrosis. methods. expression of fgf in tumor tissue was determined from tissue specimen obtained from patients with colorectal carcinoma by rt-pcr relative to gapdh. furthermore immunostaining in carcinoma, adenoma, normal mucosa and liver metastases was performed. the biological function of the growth factor was analysed using cell lines expressing high (sw ) or low fgf (caco , lt , vaco ) as a model. low expressors received exogenous fgf while expression in sw cells was knocked down by sirna. the effects on tumor cell growth was determined by mtt and colony formation assays. signaling events were investigated by western blotting. in addition paracrine effects on fibroblasts and endothelial (huvec) cells were investigated using scratch assay for migration and tube formation for blood vessel formation. results. addition of the growth factor to the culture medium of slowly growing colorectal tumor cell lines lt , vaco and caco stimulated growth within hours. the stimulatory effect involved increased phosphorylation of erk = - minutes after factor addition and increased phosphorylation of s - minutes after fgf addition. sw cells that produce large amounts of autocrine fgf were not affected within this time frame, but fgf supported tumor cell survival under conditions of serum starvation. in addition down-modulation of fgf production by sirna significantly reduced colony formation after plating at low density in sw cells and restored sensitivity to exogenous fgf . secreted fgf also affected colonic fibroblasts inducing growth and migration and stimulated huvec cells to differentiate. conclusions. fgf is upregulated during tumor progression in the majority of the investigated patients. we showed that fgf can induce both autocrine and paracrine effects on the epithelial as well as the stromal compartment of colorectal tumor cells to further tumor growth, spread and neovascularization. this makes fgf an oncogene. further studies should prove the clinical relevance of fgf as a prognostic marker and as a potential target in antitumor therapy. p immunohistochemical peculiarities of gastric carcinomas in patients younger than years c. w. schildberg , a. dimmler , s. merkel , t. littwin , w. hohenberger , t. horbach background. young patients ( < years) comprise - % of all gastric carcinomas. therefore, immunohistochemical peculiarities were analyzed in our facility. methods. the examined group had patients. the median age of the group was years ( - years), the ratio male= female was . = . tumor tissue, which was embedded in paraffin, was initially marked, so that it could be further examined using the tissue array technique and consequently immunohistochemically stained. following this, the following markers were analyzed: cox , egfr, e-cadherin, p , tff and cdx . after semi-quantitative representation, a link to data of the tumor register was performed. results. in the younger patients, the diffuse type (laurén-classification) was overwhelmingly represented with %. early tumor stages (i and ii) were distributed similarly with % as advanced stage carcinomas with %. the -year survival rate was %. notable was that stage iiia had a distinctly better -year survival rate with % than those patients with stage ii ( %). in our evaluation of the immunohistochemical stains, it showed that younger patients with the diffuse type showed significantly more down-regulation of cox . this is particularly noticeable when one compares tumor stages ii and iiia ( vs. %). with tff , there was a notable over-expression shown (p > . ) in stage ii and iiia ( vs. %). cdx and e-cadherin were significantly more frequently extracted for the diffuse type. conclusions. it is known that younger patients with worse histological results (diffuse vs. intestinal = %) display a better -year survival rate. in particular, there seems to be a difference between stages ii and iiia. this could be contributed to and explained by a down-regulation or an over-expression of cox or tff . p toxic responses and side effects using various antineoplastic drugs in an experimental setting of peritoneal carcinomatosis in rats a. hribaschek , k. ridwelski , f. meyer , d. kuester , w. halangk , h. lippert background. during the last decade, intraperitoneal (i.p.) chemotherapy against peritoneal tumor spread originating from gi-cancers has been increasingly used. the aim of this systematic comparative study was to investigate various toxic responses=side effects of various cytostatic substances, which had been primarily tested for their efficacy to prevent=treat experimentally induced peritoneal carcinomatosis in rats. methods. using a basic experimental trial, established= novel antineoplastic drugs such as mitomycin ( mg=m ), cisplatin ( mg=m ), -fu ( mg=m ), oxaliplatin ( mg=m ) and cpt- ( mg=m ) (limited dosage adapted according to their ld ) were applied i.p. to prevent=treat peritoneal carcinomatosis induced in rats by transfer of , , tumor cells (colon adenocarcinoma cell line cc- ; cell-lines service, heidelberg, germany) via laparotomy (groups of animals per drug; control groups [sham operation ae tumor cells]). animals were sacrificed under general anesthesia on the th postoperative day and autopsied. toxic responses=side effects were characterized by occurrence of i) necrosis assessed as ''þ'' vs. ''À'' (equal to yes=no) at the peritoneal surface, ii) hepatic necrosis, iii) bleeding at the mesenteric tissue, and iv) death. the cytostatic effects were used as control for the therapeutic efficacy of the agents indicated by tumor weight and '' ae '' detectable tumor growth, which were correlated with the nonfavorable adverse phenomenons. results. (table ) : mitomycin and cisplatin were the most toxic substances (e.g., peritoneal necrosis in and animals out of , respectively) comparing the chemotherapeutic drugs but, however, this correlated with the most pronounced cytostatic effect (no detectable tumor growth). though the use of oxaliplatin showed also a high rate of necrosis (n ¼ = ) and death (n ¼ = ), its therapeutic potential was only low (tumor detectable in each animal). it was not surprising that the occurrence of necroses at the peritoneal surface was the most sensitive characteristic of toxic responses=side effects. in addition, the induction of a treatment-related bleeding was associated with earlier death prior to the th day after tumor cell transfer, the end of the experimental observation period, in the majority of cases. interestingly, cpt- provided the best compromise in decreasing i.p. tumor growth on one hand and an acceptable rate of side effects on the other hand. conclusions. the results suggest that, despite some favorable effects of novel=established cytostatic drugs in i.p. chemotherapy, toxic responses=side effects need to be simultaneously tested even in earlier stages of drug development as well as experimental=clinical studies for an appropriate dose escalation=adaptation. further studies should also focus on other parameters=study characteristics, e.g., i) combination of drugs, ii) various application time=mode (e.g., i.p.=i.v.), and iii) effects on wound=anastomosis healing as well as iv) induction of peritonitis. p retrograde reperfusion via inferior vena cava reduces ischemia= = =reperfusion injury after orthotopic liver transplantation in a rat model methods. in a pilotstudy patients with a significant internal carotid stenosis will be investigated prae-and postoperatively for visual field changes. results. at the time of the congress we will present the study design in detail and early results. conclusions. in case of no changes perioperatively, the study will be closed. in case of perioperative changes a larger prospective trial with additional neurological assessment will follow. p occlusion of the common femoral artery after misplacement of an angio-seal tm vascular closure device t. ott, p. konstantiniuk, t. cohnert background. femoral closure systems are becoming increasingly popular. they promise to shorten both the time to hemostasis and to mobilization. the most frequently used systems are angio-seal(tm), perclose + and vasoseal + . case report. a -year-old male patient underwent successful percutaneous transluminal coronary angioplasty, stenting and hemostasis with angio-seal tm , which, however, was followed by acute deterioration of pre-existing stage iib peripheral arterial occlusive disease (paod) with incomplete ischemia of the right lower extremity and development of a dry necrosis of the right great toe. magnetic resonance angiography showed occlusion of both superficial femoral arteries (afs) and of the right common femoral artery (afc). intraoperatively, the right afc was found was found to be completely occluded by a collagen plug from the angio-seal(tm), which was removed without difficulty. the symptoms improved significantly after the operation. due to the patient's critical cardiac situation, no further reconstructive measures were undertaken. conclusions. the literature indicates that femoral closure systems have led to complications in the form of vascular stenoses or occlusions that are unknown with conventional compression. these systems may be contraindicated in patients with known paod. background. ablation of the vein by endovenous laser treatment (evlt) is a new procedure that is less invasive than surgery and has a lower complication rate. evlt works by means of thermal destruction of venous tissues. methods. we retrospectively analysed the results of the endoluminal laser-treatment, which we applied at patients in a time frame of years ( - ) . we compared them with the effect of the traditional surgical approach ligation and division of the saphenous trunk and all proximal tributaries followed by the stripping of the vena saphena magna. results. there was no significant difference in the rezidiverate between endoluminal laser technique and the traditional stripping of the vena saphena magna. the biggest problem of the laser technique appeared to be a lower sensibility in the range of the inner ankle during a year ( %). in % of the cases the vena saphena magna was rechannelled. and also % reported about a still noticeable cord for a year. ninety six percentages demonstrated remarkable improvement. conclusions. the evlt-procedure is simple and effective. it takes less than an hour and get patients back to their everyday activities right away. with a high success rate and minimal side effects evlt is a new standard in varicose vein treatment. although we know that saphenofemoral recurrence occurs even after correct saphenofemoral ligation, it does not imply that this ligation has become obsolete. background. this study presents long-and short-term results after surgery of currently active, chronic venous leg ulcers, focusing on the effects of ulcer healing, recurrence and concomitant risk factors. methods. between january and march , patients ( legs) with a currently active, chronic venous leg ulcer were surgically treated, based on the two main steps of functional phlebologic surgery: the surgical interruption of reflux in the superficial and perforating veins to reduce venous hypertension in the entire leg and=or the affected area and occasionally, the surgical procedure involving the ulcer. a total of patients ( legs) who came to the follow-up were examined. the data collection included a preoperative examination incorporating medical history and clinical diagnoses and various measurements at the follow-up. results. initial ulcer healing occurred in % of the cases ( legs), % ( legs) of the venous ulcers never healed, and recurrent venous ulcers occurred in % ( legs). conclusions. we conclude that surgery is indicated before an ulcer is intractable to treatment. based on the understanding and identification of the causes and symptoms of venous ulceration we recommend standard surgical methods for the therapy of venous leg ulcers at any stage. background. popliteal artery aneurysm (paa) is a rare condition with an incidence of approximately % in men ( - years). it involves the risk of peripheral embolism or progressive thrombosis that may result in acute or chronic ischemia with claudication or loss of the extremity. distal vessels are increas-ingly embolized through a persistent dispersion of mural thrombi, and the possibilities for surgical vascular reconstruction are limited by the absence of open outflow vessels. case report. a -year-old male patient with an acute ischemic left leg was referred for emergency treatment. he presented with a -year history of intermittent claudication in his right leg. no signals were detected by duplex screening above the foot arteries of the left leg, and typical symptoms of acute occlusion were present. imaging tests revealed a paa on each side (diameter left cm; right . cm). the left paa was completely occluded, the right paa was partially open but the distal popliteal artery and the the posterior tibial artery were already completely occluded. a vascular bypass reconstruction to improve circulation was not possible due to occlusion of the outflow vessels. the patient was treated conservatively (systemic heparinization, i.v. prostacyclin administration). circulation in the left leg gradually improved, with remaining claudication, a free walking distance of m, and rest pain. amputation was prevented for the time being. conclusions. elective surgery for asymptomatic paa > cm is recommended to prevent permanent limited mobility or amputation. the procedure of choice is to ligate the aneurysm and to restore blood flow by a concurrent interposition of a vein segment, from the superficial femoral artery to the open infragenual popliteal artery. the male risk population ( þ) should undergo duplex screening of the popliteal artery. while asymptomatic aneurysms > cm should be treated surgically, smaller ones should be observed, since aneurysms < cm in diameter have a distinctly lower occlusion and amputation rate. in symptomatic cases a revascularisation with venous bypass should be attempted, if there are open outflow vessels to connect the venous graft to. if a vascular bypass reconstruction is not promising a conservativ treatment may prevent amputation. background. three dimensional motion analysis is a new evaluation method of upper extremity function. this video based system provides accurate and reproducible d kinematic data by tracking movements. the method is derived from clinical gait analysis which has already reached global acceptance within this field. it should overcome the deficiencies of subjective investigations. in order to demonstrate the use of the system the analysis of patients with brachial plexus lesions before and after surgical treatment is presented. methods. a d optoelectronic camera system with passive markers was used to capture the possible active rom. twenty seven markers coated with retroreflective tape were applied over anatomical landmarks on both upper limbs and recorded simultaneous by cameras. a -dimensional reconstruction of the position of the markers was done by special designed software. joint centres and joint movements were calculated by using the expert vision and orthotrak software (motion analysis corporation). healthy probands and patients suffering from brachial plexus lesions and receiving primary nerve surgery or secondary reconstructive procedures were investigated. results. the motion curves of all, probands and patients with different questions argue for a reproducible motion sequence. we were able to produce and analyse static data, rom and position of segments as well as kinematic data, especially motion curves of distinct movements. moreover compensatory movements could be investigated. obtained pre-and postoperative kinematic data document the enhancement of the involved limbs' function. conclusions. the method enabled objective analysis of patients suffering from brachial plexus lesions. measured angles are reliable and reproducible but generally lower than angles obtained from physical measurements. this is due to several reasons concerning the biomechanical model. because of the more complex nature of upper limb kinematics the transfer of the system from lower to upper extremity still involves unsolved problems. p thoracic outlet syndrome: objective criteria to indicate surgery g. weigel, b. gradl, m. mickel, w. girsch background. reviewing the literature the indication for thoracic outlet syndrome (tos) -surgery is based on clinical findings only in the majority of the cases due to lack of objective findings. in a retrospective study we have analyzed our cases in order to evaluate objective criteria for surgical intervention. methods. seventeen patients ( men, women aging from to ) were diagnosed clinically times for tos (duration of symptoms months, nrs ). additionally objective investigations were performed: x-ray of the cervical spine to detect a cervical rib; a comprehensive electroneurographic investigation to detect signs of nerve compression; mr-angiography of the subclavian artery with elevated and adducted upper extremity to detect a stenosis of the artery as an indirect sign of compression of the brachial plexus. results. concerning the objective assessment a cervical rib was present in % of our cases. the electroneurographic investigation revealed signs of nerve compression in % of our cases. in nearly % of our cases a stenosis of the subclavian artery confirmed the clinical diagnosis. all patients underwent tos-surgery via a small single supraclavicular incision and recovered from their symptoms. conclusions. in our series we did base the indication for tos surgery not only on clinical examination but also on objective findings, either the presence of a cervical rib and=or positive electroneurographic findings and=or a stenosis of the subclavian artery. the mr-angiography was the most significant investigation to objectify the clinical findings. the presented investigation setup seems to be appropriate to objectively diag-nose tos and indicate surgery. the small supraclavicular incision gave adequate access to perform neurolysis of the brachial plexus, scalenotomy and resection of cervical or first rib without major complications in all cases. background. the necessity of antibiotic prophylaxis in the clinic of child surgery is caused by following: -increase invasive method of investigation; -increase cases of postoperative supurative complication; -high economic expenses; -spreading of polyresistent microorganism. methods. the clinic retrospective investigation of the patients, who were treated in the surgical department of lviv regional children's hospital ''ohmatdyt'' from till yr. the antibiotic prophylaxis was performed in surgical operation of ii category (conventional purity) and iii category (contaminational) of purity, which are accompanied by middle or high individual risk of the development of pyo-septic complications. eighty two of the patients took combined medications of clavulane acid with amoxicillin (augmentin, amoxuclav in dose mg per kg, the others patient took cephalosporinus of i-ii generastion (cephazolinum, cephuroximus in dose mg per kg) conclusions. effective abp allows to reduce the amount of the postoperative complications ( group- %, group- %), postoperative fever ( group- . %, group- . %), duration of the hospital treatment in the group- . days, in the group- . days), and treatment expenses. optimal drugs of choice for abp in the clinic of pediatric surgery are combined preparations of clavulane acid with amoxicillin. the goal of this study was to improve the results of management children with bat. one hundred twenty-eight children with the age ranged from weeks to years were enrolled in this study. among these patients the splenic injury was established in ( . %), liver injury -in ( . %), intraperitoneal hematoma -in ( . %), and retroperitoneal hematoma -in ( . %) of patients. according to the moor's classification grade i of the liver damage was established in patients, grade ii -in , grade iii -in , and grade iv -in one patient. according to the classification of american association of trauma surgery the grade i of splenic injury was diagnosed in patients, grade iiin , grade iii -in , grade iv -in , and grade v -in patients. laparoscopic drainage of abdominal cavity was performed in patients with active bleeding, which stopped by the surgicel + (ethicon) and electrocoagulation, from the hematoma of mesocolon and mesojejunum and in patients with grade i liver and splenic injury. the laparoscopic coagulation with applying of surgicel was performed in all patients with grade ii liver and splenic damage and in patients with grade iii. laparotomy was performed in patients with grade iii and in all patients with grade iv-v. resection of the spleen was applied in patients with grade iii and in two patients with grade iv. for the bleeding control, the surgicel nu-knit + (ethicon) was used in one patient with the grade iv of splenic damage. splenectomy was performed in patients with the grade v. parenchymal suture was used in patients with the grade iii of the liver damage and non-anatomical resection -in one patient with grade iv. retroperitoneal endoscopy with coagulation was performed in all patients with retroperitoneal hematoma. one child died with the grade iv of the liver damage. thus, the endoscopic coagulation with applying of surgicel + is effective in the management of patients with bat. the choice of management dependent of the grade of damage. we used malone antegrade continence enemas (mace), administered through a continent cutaneous appendicostomy or a caecal flap to achieve reliable evacuation and faecal continence in seven children with myelomeningocele and after surgery of anorectal malformation. postoperative complications included one subcutaneous pericaeceal abscess requiring exploration and in one case stenosis of the stoma. except well known and already described complications all seven patients are continent of stool at a mean of months follow-up. despite our efforts to develop an effective bowel management program regarding application of the enema regimen this procedure provided some technical problems especially for children who have had prior appendectomy. so we developed a new simple technique to perform a caecal tube stoma. we also want to demonstrate a new device to simplify handling and application of enemas. the basic idea of a simple method of bowel cleansing like mace is followed by significant improvement in quality of life and more social acceptance of patients. but overall success will be achieved by improvement of technical procedure and handling. extended caecum. the appendix could not be detected. a surgical intervention was decided with the intention for an appendectomy. at the operative sight a caecum duplex was revealed. the lumen of the blind caecum was completely filled by a large fecolith. also the appendix vemiformis was inflammated. caecal duplex resection and an appendectomy was performed. the pathology report described ulcerations and segmental ischemia of the resected caecum. an oxyuriasis of the vermiform appendix was also reported. there was no immediate or delayed post-operative complication. conclusions. approximately % of duplications have been reported to be located within the abdominal cavity. small bowel lesions are the most commonly described ( %), while colonic lesions are found in % of cases. a review of the literature has revealed cases of colonic duplications, that occurs mostly in pediatric patients. surgical intervention is indicated in case of complicated colonic duplications such as obstruction of the colon as a result of direct compression, volvulus, hemorrhage, ulcerations, ischemia or perforation. in most instances duplications can be completely excised as described in our case. special care should be taken of the possible abnormal blood supply to the adjacent intestinal segment. background. reports on complications are part of every medical scientific investigation. regarding the definition of a surgical or post-interventional complication there are different views. this is one reason for the variation width in complication reporting concerning the same interventions in the surgical literature. the following work presents the advantages of a prospectively standardised documentation of complications in a surgical department as a part of a hospital quality management. methods. over a period of one year in patients data sheets about post surgical complications were collected and entered in a electronically data base. all abdominal procedures, including the abdominal wall and additionally varices surgeries were enclosed in the following evaluation. patients were excluded from the investigation when treated in the surgical ambulatory or treated as day-surgical patients. the complication system according to clavien was used to classify the complication grades. this system encloses five grades, lower grading indicating lower level of complication whereas grade three is divided in subclasses a and b (dindo et al. ( ) ann surg : - ) . for statistical analysis the mann-whitney u-test and spearman correlation were used (p < . ). results. out of operations there were ( . %) operations according to our inclusion criteria with patient's average age of . ae . years ( . % male patients). the overall complication rate according to clavien averaged . % (differences between different surgical methods and surgeons are given in a table). referring to general used grading the mean complication rate ranged between . and . %. conclusions. using the system of clavien complication rates appear higher than usual. this is caused by the fact that all post surgical events apart from normal stay slip into the system. the system allows a good comparability between single surgeons and between different operations. results from prospectively entered data evaluation can be used to detect weak points in a team, and to find out technical as well as personal problems. as a consequence, for instance education programs could be provided to compensate weaknesses or the team could be restructured. periodical evaluation of a standardized data bank allows fast reactions to occurring problems and guaranties an adequate surgical complication management. lymphatic vessel invasion (lvi) has been rtx=ctx þ esophagectomy). ( -ac): n ¼ : n ¼ (esophagectomy) vs. n ¼ (ctx þ esophagectomy). results. ( -escc): rtx=ctx led to a lvi-reduction detectable lvirate: ( -escc): rtx=ctx led to significant lower lvi-rates compared to primary resected patients tyrolean cancer research institute, innsbruck, austria; department of pathology germany p the role of fgf in colorectal carcinogenesis institut für krebsforschung p , p , p sachsenplatz - , wien, Ö sterreich. -datenkonvertierung und umbruch: manz crossmedia druckerei ferdinand berger & söhne gesellschaft m. b. h., horn, Ö sterreich. -verlagsort: wien. -herstellungsort: horn. printed in austria p. b. b.= = =erscheinungsort: wien= = =verlagspostamt wien background. survival of patients with lung cancer is strongly affected by lymph node metastases. identification of n disease is thus crucial. we compared the diagnostic accuracy of image fusion of positron-emission tomography (pet) and computed tomography (ct) with that of ct only and that of pet only for mediastinal lymph node staging in patients with non-small-cell lung cancer (nsclc).methods. in patients with proven nsclc a preoperative fdg-pet and ct examination of the body trunk were performed. pet, ct and pet-ct image fusion were evaluated separately; nodal stations were identified according to the mapping system of the american thoracic society. a lymph node was considered to be infiltrated by tumor if the minimal diameter was cm or more in ct, or the standard uptake value (suv) was larger than . in pet. all patients underwent mediastinoscopy, biopsies from lymph node regions were taken (ats . %, ats . %, and ats . %). if primary pulmonary resection was achieved, ipsilateral lymph nodes were dissected and the histological findings were considered for statistical analysis. histological findings were compared with results of ct, pet and pet-ct image fusion. sensitivity and specificity were obtained using the confusion matrix.results. histopathological assessment revealed positive mediastinal lymph nodes out of , sensitivity was . % for ct, . % for pet and . % for image fusion, specificity was . % for ct, . % for pet and . % for pet-ct fusion.conclusions. pet-ct image fusion improves sensitivity, specificity and accuracy in mediastinal staging of nsclc patients. the high negative predictive value of pet-ct image fusion ( . ) may abandon mediastinoscopy in nsclc patients with negative mediastinal pet-ct image fusion. however, larger series are mandatory in order to gain statistical significant power. local resection of stage i primary lung cancer by -nm nd-yag laser in functionally inoperable candidates: a prospective study s. b. watzka , w. grossmann , p. n. wurnig , f. lax , m. r. mü ller , p. h. hollaus background. hydatid disease is a parasitic infestation by a tapeworm of the genus echinococcus. it is not endemic background. in a pathway regarding the management of liver trauma was established in our hospital. the aim of the study was to assess the outcome after implementation of the guidelines.methods. data on all patients with liver injuries managed in our institution in the past years was evaluated. liver trauma was classified using moore's trauma score. additionally, coexisting injuries were assessed.results. from to a total of patients with liver trauma (motor vehicle accidents , falls , horse riding accidents ) were admitted to our trauma unit (median age of . years). grade iii traumas ( . %) were the most common injuries, followed by grade iv ( . %), grade i ( . %), grade ii ( . %), grade v ( . %) and grade vi ( . %). the laparotomy rate varied from . % in grade i injuries to % in grade v injuries, resulting in an overall laparotomy rate of . %. two patients required second look laparotomy for removal of liver packing and one patient required puncture of a posttraumatic bilioma. the most common associated concomitant injuries were right or bilateral rib fractures ( ), pelvic fractures ( ), long bone fractures ( ), laceration of the spleen, spine injuries ( ), and head injuries ( ). the mortality rate of patients with liver trauma ranged from % in grade iv injuries to % in grade i injuries with an overall mortality rate of % ( ). all patients with grade v or grade vi traumas survived ( ). if laparotomy was required because of hemodynamic instability or concomitant abdominal injury the mortality rate increased to %.conclusions. the clinical pathway of management of hepatic trauma in our patients showed favourable results. apart from the grade of liver injury the overall laparatomy rates and mortality rates largely depend on concomitant injuries. colitis cystica profunda is a rare benign disorder of the large intestine characterized by submucosal cyst formation. the clinical appearance of the disease can be highly variable; it can be associated with rectal prolapse and chronic inflammatory bowel disorders such as crohn's disease and ulcerative colitis.we describe a case of colitis cystica profunda associated with rectal prolapse. the female patient had a one-year history of constipation and rectal pain. an altemeier procedure was performed to correct the rectal prolapse. histology confirmed the presence of colitis cystica profunda. the operative and postoperative course was uneventful.it should be borne in mind that colitis cystica profunda can be associated with rectal prolapse. conservative management is usually satisfactory, but a mucosal resection (delorme's procedure) or perineal protectomy (altemeier procedure) is recommended when there is rectal prolapse.p peritonitis ossificans -a rare situation after acute major abdominal surgery m. ruzicka , s. thalhammer , s. stättner , m. mostegel , b. sobhian , j. karner background. treatment of the congenital intestinal obstruction of newborns is one of the main problems of the pediatric surgery.methods. patient p. had been hospitalized to the intensive care unit days after birth with symptoms of absence of stool from birth, frequent vomiting, full-blown abdominal distension. the signs of endotoxicosis, the intestinal loops posterized image through the anterior peritoneal wall, dilatation of the venae anterior peritoneal wall, abdomen lower sections and scrotum edema were noted at the time of admission. x-ray of the abdominal cavity reveals the signs of the low intestinal obstruction, bowel perforation -presence of liquid and free air at the abdominal cavity. diagnosed -the intestinal obstruction, peritonitis and after a short-term of the preoperative preparation patient underwent surgery. atresia of the sigmoid colon, necrotic enterocolitis with the affection of the = of the large bowel, perforation of rising section of the large intestine, the meconium peritonitis were established during surgery. the right side hemicolectome, terminal ileostomy and transverse colostomy. the reoperation at the month was done: ileotransversostomy, descendosigmostomy with the preserving of transverse colostomy were performed. the diameter of the descending large bowel exceeded the diameter of the sigmoid colon by - . times, that's why the anastomosis had been raised by the type ''side to side''.results. within the course of weeks after the radical surgery the child started to have stool passage through the rectum. presently the child's condition is satisfactory, the physical development corresponds to the age norms, stool passage takes place only through the rectum. the final stage of the treatment will be the closure of the transverse colostomy with the complete restoring of the passage of the chyme through the bowels.conclusions. the bringing of the intestinal stomas out with the delayed radical surgery in some case of newborns may significantly improve the prognosis of the results of treatment. background. different inguinal hernia operationtechniques must be compared to their recurrency rate, acute and long term complication rate, patients comfort and duration before returning to daily life, return to work and to sports etc. under economical aspects they should be safe, quick, and require limited resources (personal, equipment, implantate). with increasing economical pressure the latter features gain increasing importance. we therefore made a comparative time analysis between tipp and lichtenstein.methods. between . . and . . hernias were operated in tipp technique and hernias in lichtenstein (lich) technique. patients were from an identical district and comparable in epidemiological data, comorbidity, hernia distribution and in-resp outdoor treatment. each series was performed by surgeon in the same operation unit. implantates used were polysoft hernia patch tm (tipp) and ultrapro mesh tm (lich). total operation time was recorded (min). additionally, operation phases were defined:opening phase: from skin split to preparation phase: from opening of the external aponeurosis to introduction of the mesh repair phase: from introduction of the mesh to the end of the suture of the external aponeurosis closing phase: end of repair phase to skin closure.assuming individual differences between the surgeons and management-associated differences as well as intermethodical differences relative phase intervals were deduced from the original recordings and compared. statistical comparison was done by t-test and pearson correlation coefficient.results. average operation time of lich was ae . min (range - min, median min), average operation time of tipp . ae . min (range - min, median min). up to now there was = recurrent hernia in tipp and = in lich (n.s.). the correlation of preparation phase time and operation time was high (pearson coefficient: tipp . ; lich . ) and lower for repair phase (tipp . ; lich . ). there was no difference in the correlation of the preparation phases in tipp and lich (p < . ). on this basis we estimated the expected time of the compared method to each series, i.e. presumable time for lich in tipp series and vice versa. comparison of lich vs. tipp (expected) and lich (expected) vs. tipp revealed that tipp was faster and required . % time of lich (p < . ).conclusions. tipp and lich show a comparable time effort towards preparation, tipp is significant faster in repair phase enabling a quicker total operation time.p transinguinal preperitoneal hernioplasty (tipp) using a memory ring armed polypropylene patch: which factors influence the operation?quality of life improved significantly in all patients with clip displacement.conclusions. esb has a displacement rate of less than % and gives excellent results for quality of life, which are not diminished by inappropriate clip application. grundlagen. post anal repair ist eine methode zur verbesserung der kontinenzfunktion bei diffuser schädigung des schließmuskels. die methode wurde in den letzten jahren kontrovers diskutiert. langzeitergebnisse wurden nur sporadisch publiziert. methodik. die operation wurde in der technik von parks [i] in steinschnittlage und allgemein-, oder spinalanästhesie durchgeführt. eine präoperative darmreinigung und eine perioperative antibiotikaprophylaxe wurden routinemäßig durchgeführt. prä-, und postoperativ wurde eine sphinktermanometrie in der durchzugstechnik mit einem perfundierten dreilumigen katheter vorgenommen. die auswertung erfolgte mit einem programm der firma gastrosoft. bei der klinischen untersuchung wurde der kontinenz-score nach williams verwendet.ergebnisse background. peptic ulcer in the excluded segment of a gastric bypass has been reported in the literature in only cases. we report a -year-old woman with a perforated duodenal ulcer, who underwent laparoscopic roux-en-y gastric bypass surgery for morbid obesity months ago.methods. on physical examination, the patient's abdomen was marginally tender to palpation. laboratory findings were unremarkable except for an elevated leucocyte count of . =ml (normal . - . =ml). abdominal radiography and sonography showed no pathology. because of the persistent abdominal pain we performed an abdominal computed tomography scan, which demonstrated free air.results. she was successfully treated by a laparoscopic repair of the perforated duodenal ulcer. after surgery, a standardized analgesic regimen was administered for pain relief. intravenous piperacillin-tazobactam was continued for at least days, then a helicobacter eradication therapy was performed. feeding was resumed on the first postoperative day and the patient was discharched on day six without any complications.conclusions. peptic ulcer in the excluded segment of a gastric bypass has been reported in the literature in cases. the pathogenesis of ulcer perforations in the excluded sto-mach=duodenum is unclear. of the total cases, free air in the abdominal radiography was only noted in one case. recognizing that free air under the diaphragm will be absent is one of the most important diagnostic considerations when gastric or duodenal ulcer perforation is suspected in the postgastric bypass patient. abdominal ct scan and early surgical exploration remain the treatment of choice.chirurgische forschung p blood interleukin as preoperative predictor of fatal postoperative sepsis after neoadjuvant radiochemotherapy background. a serious impediment in transplantation medicine especially after liver-transplantation is the damage by ischemia and reperfusion. we compared different types of reperfusion within a rat model and investigated the different consecutive ischemia=reperfusion injuries.methods. arterialized orthotopic liver transplantation (olt) was performed in syngenic male lewis rats. the animals were divided into experimental groups: i-and ii-control groups with antegrade reperfusion and group iii with retrograde reperfusion. laboratory parameters as well as histopathological changes of the liver-graft-tissue were evaluated , and hours after olt.results. the got-values showed hours after olt significant differences between group i=ii (antegrade reperfusion) and group iii (retrograde reperfusion) ( . ae . u=l vs. . ae . u=l; p < . ). gpt-as well as got-values were significantly lower in group iii (retrograde reperfusion) hours after olt. evaluation by histopathology revealed significant less areas of necrotic liver tissue within group iii compared to group i=ii (p < . ).conclusions. these results show that the retrograde reperfusion (by order of: infrahepatic inferior vena cava -opening suprahepatic inferior vena cava -hepatic veins -retrograde reperfusion of the liver) has a protective effect on the graft in regard to the ischemia=reperfusion injury. background. clamping of internal carotid artery during carotid endarterectomy (cea) leads to cerebral ischemia in - % of patients. routine carotid shunting has a high morbidity as described in literature. selective carotid shunting under general anaesthesia requires an intraoperative monitoring. the registration of somatosensory evoked potentials (sep) is a well accepted technique.methods. from to we assessed prospectively consecutive cea under general anaesthesia and sep monitoring, without primary shunting. routinely preoperative neurological assessment, duplex sonography and mr-angiography were performed. the onset of a clinical neurological deficit after carotid artery clamping was related to changes in the n =p waveforms in sep-recording. sep was evoked by stimulating median nerve. criteria for shunting was reduction in sep-amplitude > %. routinely postoperative neurological examination and duplex sonography were performed.results. patients underwent cea between and . intraoperativ sep-monitoring was available in patients. in patients ( . %) sep-monitoring was inadequate (primary shunting). in procedures ( . %) sep-monitoring didn't show deviations. significant sep-alterations appeared in of cases ( . %). in cases sep-alterations normalised after shunting without neurological deficits. in cases sep-alterations were reversible after shunting, but were associated with postoperative neurological deficits ( permanent, transient). cases ( . %) had normal sep-findings (false negative), but postoperative neurological deficit occurred ( permanent, transient).conclusions. the selective use of carotid shunting during cea requires an intraoperative monitoring technique. based on our data and literature findings, sep-monitoring is a reliable method to prevent neurological vascular deficits and effectively minimizes shunting frequency.p perioperative changes in internal carotid endarterectomy p. konstantiniuk , t. ott , u. gratzer , i. steinbrugger , a. wedrich , t. cohnert p poland syndrome with partial heart ectopia and dextrocardia r. kovalsky , a. kuzyk , o. leniv , i. avramenko lviv regional children hospital, lviv, ukraine; lviv national medical university, lviv, ukraine; lviv regional children hospital ohmatdyt, lviv, ukrainebackground. poland syndrome is seen in = of the newborns. it can declare itself by its different components and joining of the additional defects in every concrete patient.methods. a girl, born by the cesarean section, with the weight of g and week gestational age was brought to the pediatric surgery clinic on the . . in a couple of hours after birth. when examined the skewness and chest distortion attracted attention, especially on the right side. the oval form defect of the chest wall  cm was seen in the anterior of the chest parasternal on the right in the ii rib level from the costal margin, an also thinning of body of sternum. a part of liver with the size of  . cm covered with peritoneum was projecting form the lower part of the latter. a gastric part of the heart, covered with pericardium and non-epithelized membrane with the upper part directed to the right was projecting over it from the defect. there were no signs of heart and respiratory failure. during the echocardiography the following was discovered: heart rotation in the chest, right ventricular and atrial hypertrophy, good running of the great vessels, not violated valve function and good myocardial contractility. ejection fraction from the left ventricle %. during the intraoperative inspection the diaphragm defect in the right place parasternal triangle with the size of  cm through which the part of liver prolapses. the hepatic lobectomy was done as well as diaphragma defect repair.results. in eight months the plastic operation was done on the defect through the replacement of the front edge of the costal arch and musculocutaneous flap, formed from the greater pectoral muscle. the child was discharged from the hospital in a good shape.plastische, Ä sthetische und rekonstruktive chirurgie background. traditional abdominoplasty aims at elimination of redundant fat tissue and skin as well as tightening of muscular aponeurosis on the abdomen. in the massive weight loss (mwl) patient this procedure often yields only mediocre results. specific areas such as hips, buttocks and the lateral thigh are addressed inadequately.methods. patients after mwl are treated with a central or lower body lifting according to the specific needs at our institu-tion. the central body lift includes a circumvertical dermolipectomy concentrated on the central torso without significant mobilisation of caudal tissues. in the lower body lift, the circumvertical dermolipectomy is located more inferior on the torso with an additional extensive mobilisation of the subcutaneous tissue down to the level of the knee.results. these new innovative techniques led to a much improved contour and results compared to the traditional abdominoplasty procedure. although there is an increase in operative time, postoperative recovery and complications appear comparable according to our initial limited experience. we present in detail representative cases with step-by-step explanation of operative techniques.conclusions. especially after mwl, such as after bariatric surgery, the surgeon has to deal with a tremendous amount of redundant tissue on the lower part of the torso and thighs. traditionally this problem was solved in a staged manner with multiple surgeries, such as abdominoplasty, buttock lift or medial thigh lift. however, in many cases this approach led to unsatisfying results. new innovative techniques allow for an optimal repositioning of the descended tissues und most often to a much improved postoperative result compared to the traditional techniques. a. m. rokitansky, r. j. hahn background. we report our experience using the modified minimal invasive method of pectus excavatum repair in adults. thirty one adults with a mean age of ( - . ) suffering from pectus excavatum have been corrected using by the extended modified minimally invasive repair method. the ravitch= welsh=rehbein technique, performed elsewhere, has corrected patients insufficiently. reduced physical capacity, mild cardiac valve dysfunctions (prolapse, pulmonary valve insufficiency), chest pain in the area of the funnel and reduced ventilatory function were detected. two thirds of the patients emphasized the wish of a better cosmetic result. preoperative investigations include blood samples, ecg, heart sonography, chest x-ray, chest mri=ct with -d reconstruction and spirometry.methods. retrosternal mobilization and intraoperative stretching of the anterior thorax by long lasting sternal elevation modified the original nuss technique. additionally an oblique wedge shaped partial sternal osteotomy and=or osteotomies of the ossificated ribs were performed. in adults usually pectus pars (ps -implant + fa. hofer austria) should be used.results. due to preparation we observed intraoperative bleeding episode from the internal mammaric vessels, superficial lesion of the right visceral pleura (adhesions). postoperatively we saw pleural effusions, subcutaneous hematoma and two prolonged wound-healing episodes (superficial infections with no necessity of bar removal). vertebral index changed from . preoperatively to a normal range of . postoperatively. postoperative cosmetic results were perfect in %. in summary adults with pectus excavatum are manageable with extremely satisfactory results using the described extended modified correction technique. osteotomies do not destabilize the chest and can be sufficiently combined with the nuss technique. background. minimal invasive av-valve surgery is an increasingly popular procedure in cardiac surgery, but -due to the complexity -still reserved to few selected centers. aim of this study was to present learning curve issues for program introduction. methods. a total of minimal invasive av-valve procedures were performed by a single surgeon and were successful in ( . %). seventy one patients ( . %) underwent av-valve repair, ( . %) received mitral valve replacement. in patients ( . %), concomitant asd closure and=or tricuspid valve repair had to be performed. one intraoperative conversion to valve replacement had to be performed due to residual mitral regurgitation. for calculation of learning curves, regression models with logarithmic curve fit for operating time (ot), aortic cross-clamp (axt) and cardio-pulmonary bypass time (cpbt) for all patients and for patients with posterior mitral leaflet prolapse were applied.results. within approximately consecutive minimal invasive procedures, a steady decline of either ot, axt and cpbt could be observed for the overall surgical population even despite the increasing number of concomitant procedures and was similar in patients with posterior mitral leaflet prolapse. after overcoming this steep learning curve, a mean axt of ae min, a cbp time of ae min and a total ot of ae min is required to treat isolated posterior leaflet prolapse.conclusions. minimal invasive av-valve surgery can be safely introduced into a heart surgery program. however, sufficient number of cases per year are required per surgeon to come over this learning curve. case report. a -year-old male patient without clinical symptoms presented an enlarged heart shadow in a routine radiological examination. the following ct revealed a structure in the pericardial sac that was initially classified as a pericardial cyst. in order to confirm the diagnosis, an ecg-triggered multi-slice ct was performed resulting in the diagnosis of a gigantic coronary fistula originating from the left main coronary artery leading to the right atrium. the shunt volume of the coronary fistula was estimated to be %. echocardiography demonstrated dilatation of the right chambers due to volume overload. since operative mortality was deemed extremely low in this patient surgical correction was advised. after median thoracotomy, initiation of heart lung machine and extensive cardioplegia, the coronary fistula was identified to originate from the left main coronary artery meandering around the posterior side of the left heart with a mean diameter of cm and entering the right atrium at the level of the vena cava superior. the fistula was ligated in the right atrium and at its origin at the branching site of the circumflex artery. to secure optimal surgical outcome bypass grafting was performed to lad (left anterior descending) and its diagonal branch as well as the circumflex artery. postoperatively performed ecg-triggered multislice-ct evidenced successful repair of this anatomical malformation. the postoperative course was uneventful. background. to document severity of illness and to evaluate the predictive value of clinical scoring systems in infants and children after cardiac surgery. prospective study with follow up to hospital discharge. a bed multidisciplinary paediatric icu in a university hospital. between = and = infants and children were admitted after open heart surgery.methods. data relevant to the acute physiologic score for children (apsc), pediatric risk of mortality (prism iii), therapeutic intervention scoring system (tiss ) and organ system failure (osf) score were collected in all patients during the first days of postoperative intensive care. eighty one percentages of the patient underwent a total repair, % had a palliative correction.results. the mean age of the patients was . ae . years. there were survivors (s) and non survivors (ns). the mean duration of mechanical ventilation was . ae . days for survivors and . ae . days for non survivors. on the first postoperative day the mean apsc and prism iii scores of survivors and non survivors were . ae . vs. . ae . (p < . ) and . ae . vs. . ae . (p< . ), respectively. the mean tiss and osf scores of survivors and non survivors were . ae . vs. . ae . (p< . ), and . ae . vs. . ae . (p< . ), respectively. the overall hospital mortality rate was . %. patients with an apsc score < and a prism score < had a survival rate of %, whereas patients with an apsc score > and a prism score > had a mortality rate of %. the area under the receiver operating characteristic (roc) curve for apsc, prism, osf and tiss was . , . , . and . , respectively.conclusions. apsc, prism and tiss describe accurately the severity of illness in infants and children after cardiac surgery, and all physiologic scores identify those patients at increased risk for mortality.p non-bacterial pyopericardium leading to lethal sepsis in a patient with severe humoral immunodeficiency k. mészáros , i. knez , b. rigler , g. p. tilz klinische abteilung für herzchirurgie, graz, austria; abteilung für klinische immunologie, graz, austriabackground. pyopericardium is the accumulation of pus in the pericardium mainly caused by bacterial infection. purulent pericarditis most commonly occurs as a direct extension of an infection from an adjacent pneumonia or empyema. alternatively, a distant infection can haematogenously seed the pericardium. primary pericardial infection is rather rare. pyopericardium is an illness requiring acute intervention by the heart surgeon (pericardial drainage) and adequate medication.methods. a -year-old man was admitted with diffuse chest pain, dyspnoea, tachycardia and nausea. laboratory examination revealed massive leukocytosis and elevation of creactive protein. echocardiogram showed circumferential pericardial effusion without valvular vegetations. after a subsequent clinical impairment to a highly septic state, he underwent surgical pericardial drainage. the pericardium was full of pus of creamy aspect. after continuous pericardial lavage and operative revision in several steps, final sternal closure took place ten days later. no infectious agent could be identified to be responsible for the purulent pericarditis.at the term of next surgery, . litres of serous ascites and . litres of serous pericardial effusion were drained. the patient developed a gangrenous cholecystitis, op-site findings revealed a non-purulent ascites, intra-operative cholangiography was without pathological findings.results. detailed immunological analysis showed a severe decompensated immunodeficiency with adentritocytaemia. the therapy with polyvalent immunoglobulin and imutin was ineffective, the patient died one day later from a therapy-refractory septic shock.conclusions. in cases with unclear non infectious purulent pericarditis, it is of high importance to carry out the correct diagnosis as soon as possible to provide an adequate therapy. background. early results of mi treatment of proximal humeral fractures using the ncb + -ph plate showed promising results reaching points ( % of age related normal value) in the constant score months postoperatively and an acceptable complication rate ( . %). the purpose of this study was to analyze the long-term results focusing on functional outcome and complications.methods. so far out of a total number of cases we have gained the data of patients ( women, men; age in the mean) who sustained fractures of the proximal humerus treated mi with the ncb-ph + plate (zimmer company, winterthur, switzerland). in cases ( %) osteoporosis had been diagnosed preoperatively. radiological follow-up in two planes and functional outcome is assessed clinically (rom) and using visual analogue scale (vas) for pain and function, constant score and a modified adl score (activities of daily living).results. average rom (in degree) for anteversion was , glenohumeral abduction , external rotation and internal rotation . average vas for pain was , points ( ¼ worst) and for function , points ( ¼ best). average constant score was points, average adl score was points ( ¼ best). between and months postoperatively one case ( , %) of sintering of the humeral head and one case ( , %) of avascular necrosis was detected. in cases ( %) of reversed impingement we performed total removal of hardware. four younger patients ( %; age in the average) underwent the same procedure demanding it though not suffering of limited rom or pain.conclusions. in the early results ncb-ph + proved to be an effective mi method of treatment of fractures of the humeral head. the year follow up data show further functional improvement (approx. % of constant score). the complication rate remains low ( = ¼ %). especially, no cases of lesions of the axillary nerve or frozen shoulder were seen. the latter we believe is due to the mi procedure and the early functional treatment which is possible since the ncb-ph + plate creates high primary stability. the long-term results prove the ncb-ph + plate to be a safe and effective method of treatment reaching a functional outcome that enables the mostly old patients to regain an acceptable level of activity. removal of hardware is easy to perform and offers especially in the younger patient a possibility to at least improve patients' subjective outcome. background. the gastrointestinal duplication in adults is a rare congenital abnormality and only few cases are described in the literature. although intestinal duplications are considered to be benign lesions, mostly asymptomatic, they may result in significant morbidity and mortality, if left untreated. this study reports of one case of caecal duplication with an overview of the literature.methods. a -year-old female patient was hospitalised with pain in the right lower abdomen. a relocatable and solid tumor ( cm dm) was palpable. blood examination revealed a slight increase of leu and crp. the gynaecologic examination was entirely unremarkable. the sonography showed only an key: cord- -rzrfkkci authors: dua, pami title: monetary policy framework in india date: - - journal: indian econ rev doi: . /s - - - sha: doc_id: cord_uid: rzrfkkci in , the monetary policy framework moved towards flexible inflation targeting and a six member monetary policy committee (mpc) was constituted for setting the policy rate. with this step towards modernization of the monetary policy process, india joined the set of countries that have adopted inflation targeting as their monetary policy framework. the consumer price index (cpi combined) inflation target was set by the government of india at % with ± % tolerance band for the period from august , to march , . in this backdrop, the paper reviews the evolution of monetary policy frameworks in india since the mid- s. it also describes the monetary policy transmission process and its limitations in terms of lags and rigidities. it highlights the importance of unconventional monetary policy measures in supplementing conventional tools especially during the easing cycle. further, it examines the voting pattern of the mpc in india and compares this with that of various developed and emerging economies. the synchronization of cuts in the policy rate by mpcs of various countries during the global slowdown in and the covid- pandemic in the early s is also analysed. the monetary policy framework in india has evolved over the past few decades in response to financial developments and changing macroeconomic conditions. the operational framework of monetary policy has also gone through significant changes with respect to instruments and targeting mechanisms. the preamble of the reserve bank of india (rbi) act, was also amended in , which now clearly provides the mandate of the rbi. it reads as follows: "to regulate the issue of bank notes and keeping of reserves with a view to securing monetary stability in india and generally to operate the currency and credit system of the country to its advantage; to have a modern monetary policy framework to meet the challenge of an increasingly complex economy; to maintain price stability while keeping in mind the objective of growth." the aim of monetary policy in the initial years of inception of rbi was mainly to maintain the sterling parity, with exchange rate being the nominal anchor of monetary policy. liquidity was regulated through open market operations (omos), bank rate and cash reserve ratio (crr). soon after independence and through the late s, the role of the central bank was aligned with the planned development process of the nation in accordance with the -year plans. thus, it played a major role in regulating credit availability, employing omos, bank rate, and reserve requirement towards this end. with the nationalization of major banks in , the main objective of monetary policy through the s till the mid- s was the regulation of credit in accordance with the developmental needs of the country. this period was marked by monetization of fiscal deficit while inflationary consequences of high public expenditure necessitated frequent recourse to crr. in , on the recommendation of the committee set up to review the working of the monetary system (chairman: dr. sukhamoy chakravarty), a new monetary policy framework, monetary targeting with feedback was implemented based on empirical evidence of a stable demand for money function. however, financial innovations in the s implied that demand for money may be affected by factors other than income. further, interest rates were deregulated in the mid- s and the indian economy was getting increasingly integrated with the global economy. therefore, the rbi began to deemphasize the role of monetary aggregates and implemented a multiple indicator approach (mia) to monetary policy in encompassing all economic and financial variables that influence the major objectives outlined in the preamble of the rbi act. this was done in two phases-initially mia and later augmented mia (amia) which included forward looking variables and time series models. based on rbi's report of the expert committee to revise and strengthen the monetary policy framework ( , chairman: dr urjit r patel), a formal transition was made in towards flexible inflation targeting and a six member monetary policy committee (mpc) was constituted for setting the policy repo rate. the monetary policy framework agreement (mpfa) was signed between the government of india and the rbi in february to formally adopt the flexible inflation targeting (fit) framework. this was followed up with the amendment to the rbi act, in may to provide a statutory basis for the implementation of the fit framework. with this step towards modernization of the monetary policy process, india joined the set of countries that adopted inflation targeting, starting from by new zealand, as their monetary policy framework. the central government notified in the official gazette dated august , , that the consumer price index (cpi) inflation target would be % with ± % tolerance band for the period from august , to march , . at the time of writing (april ), this period is drawing to a close in less than a year. in this backdrop, this paper discusses the evolution of the monetary policy framework in india and describes the workings of the current framework. the paper is divided into the following sections. section presents a schematic representation of the main components of a general monetary policy framework and describes its key features. section describes the genesis of the monetary policy framework in india since covering the monetary targeting framework, multiple indicator approach and flexible inflation targeting. the main recommendations of rbi's report of the expert committee to revise and strengthen the monetary policy framework ( , chairman: dr urjit r patel) are also discussed. composition, workings and voting pattern of the monetary policy committee from october to march are also provided. further, a comparison of voting patterns with various countries across the globe is undertaken. section discusses a general framework for monetary policy transmission and applies the framework to india. it also describes interest rate linkages at the global level. section examines unconventional monetary policy measures adopted in late and early . section concludes the paper. the specification of the monetary policy framework facilitates the conduct of monetary policy. the general framework comprises well-defined objectives/goals of monetary policy along with instruments, operating targets and intermediate targets that aid in the implementation of monetary policy and achievement of the ultimate objectives. a schematic representation of a monetary policy framework is shown in fig. (laurens et al. ; mishkin ) . instruments are tools that the central bank has control over and are used to achieve the operational target. examples of instruments include open market operations, reserve requirements, discount policy, lending to banks, policy rate. operational targets are the financial variables that can be controlled by the central bank to a large extent through the monetary policy instruments and guide the day-to-day operations of the central bank. these can impact the intermediate target and thus help in the delivery of the final goal of monetary policy. examples of operational targets include reserve money and short-term money market interest rates. intermediate targets are variables that are closely related with the final goals of monetary policy and can be affected by monetary policy. intermediate targets may include monetary aggregates and short-term and long-term interest rates. goals refer to the final policy objectives. these may include price stability, economic growth, financial stability and exchange rate stability. this general framework is applied to the monetary targeting framework with feedback that prevailed from to and to the inflation targeting framework that exists from onwards. the multiple indicator approach that was operational from to was based on a number of financial and economic variables and was not exactly specified on the basis of this framework although broad money was treated as an intermediate target and the goals of monetary policy are the same across the various frameworks. in the s through the mid- s, monetization of the fiscal deficit exerted a dominant influence on monetary policy with inflationary consequences of high public expenditure necessitating frequent recourse to crr. against this backdrop, in , on the recommendation of the committee set up to review the working of the monetary system (rbi ; chairman: dr. sukhamoy chakravarty), a new monetary policy framework, monetary targeting with feedback was implemented based on empirical evidence of a stable demand for money function. the recommendation of the committee was to control inflation within acceptable levels with desired output growth. further, instead of following a fixed target for money supply growth, a range was followed which was subject to mid-year adjustments. this framework was termed "monetary targeting with feedback" as it was flexible enough to accommodate changes in output growth. this operational framework is depicted in fig. . (definitions of variables shown in fig. are given in appendix ). the main instruments in this framework were cash reserve ratio (crr), open market operations (omos), refinance facilities and foreign exchange operations. broad money (m ) was chosen as the intermediate target while reserve money (m ) was the main operating target. however, an analysis of money growth outcomes during the monetary targeting framework reveals that targets were rarely met (rbi (rbi - . even with increases in crr, money supply growth remained high and fuelled inflation. further, financial innovations in the s implied that demand for money may be affected by factors other than income. since the mid- s, with global integration, factors such as swings in capital flows, volatility in the exchange rate and global growth also impacted the economy. moreover, interest rates were deregulated allowing for changing interest rates and a market determined management system of exchange rates was also adopted. ( ) primary objective of monetary policy in india is to maintain price stability, while keeping in mind the objective of growth. ( ) definitions of variables are given in appendix against the backdrop of changing domestic and global dynamics, rbi implemented a multiple indicator approach (mia) to monetary policy in encompassing various economic and financial variables based on the recommendations of rbi's working group on money supply (rbi ; chairman: dr yv reddy). these variables included several quantity variables such as money, credit, output, trade, capital flows, fiscal indicators as well as rate variables such as interest rates, inflation rate and the exchange rate. the information on these variables provided a broad-based monetary policy formulation, which not only encompassed a diverse set of information, but also accorded flexibility to the conduct of monetary management. the mia was conceptualized when dr bimal jalan was governor and was implemented in two stages-mia and later augmented mia, by including forward looking variables and a panel of time series models, in addition to the economic and financial variables (mohanty ; reddy ) . forward looking indicators were drawn from rbi's industrial outlook survey, capacity utilization survey, inflation expectations survey and professional forecasters' survey. all the variables together with time series models provided the projection of growth and inflation while rbi provided the projection for broad money (m ) and treated this as the intermediate target. the operational framework of amia is illustrated in fig. . compared to the monetary targeting framework, the goals of monetary policy remained the same and broad money continued to serve as the intermediate target while the underlying operating mechanism of mia evolved over time. in may , the weighted average call money rate (wacr) was explicitly recognized as the operating target of monetary policy while the repo rate was made the only one independently varying policy rate. these measures improved the implementation and transmission of monetary policy along with enhancing the accuracy of signaling of monetary policy stance (mohanty ) . the importance of focusing on inflation was first highlighted in the report of the committee on financial sector reforms (government of india ; chairman: dr. raghuram rajan) constituted by the government of india. the report recommended that rbi can best serve the cause of growth by focusing on controlling inflation and intervening in currency markets only to limit excessive volatility. the report pointed out that the cause of inclusion can also be best served by maintaining this focus because the poorer sections are least hedged against inflation. further, the report recommended that there should be a single objective of staying close to a low inflation number, or within a range, in the medium term, moving steadily to a single instrument, the short-term interest rate to achieve it. former environment. the committee was also required to review the organizational structure, operating framework and instruments of monetary policy, liquidity management framework, to ensure compatibility with macroeconomic and financial stability, as well as market development. the impediments to monetary policy transmission were to be identified and measures along with institutional pre-conditions to improve transmission across financial markets and real economy were to be suggested. some issues central to the report were selecting the nominal anchor for monetary policy, defining the inflation metric and specifying the inflation target. a nominal anchor is central to a credible monetary policy framework as it ties down the price level or the change in the price level to attain the final goal of monetary policy. it is a numerical objective that is defined for a nominal variable to signal the commitment of monetary policy towards price stability. generally five types of nominal anchors have been used, namely, monetary aggregates, exchange rate, inflation rate, national income and price level. the expert committee recommended inflation to be the nominal anchor of the monetary policy framework in india as flexible inflation targeting recognizes the existence of growthinflation trade-off in the short-run and stabilizing and anchoring inflation expectations is critical for ensuring price stability on an enduring basis. further, low and stable inflation is a necessary precondition for sustainable high growth and inflation is also easily understood by the public. regarding the inflation metric, the committee recommended that rbi should adopt the all india cpi (combined) inflation as the measure of the nominal anchor. this is to be defined in terms of headline cpi inflation, which closely reflects the cost of living and influences inflation expectations relative to other available metrics. cpi is also easily understood as it is used as a reference in wage contracts and negotiations. headline inflation was preferred against core inflation (headline inflation excluding food and fuel inflation) since food and fuel comprise more than % of the consumption basket and cannot be discarded. the committee recommended the target level of inflation at % with a band of ± % around it. the tolerance band was formulated in the light of the vulnerability of the indian economy to supply and external shocks and the relatively large weight of food in the cpi basket. the expert committee also recommended that decision-making should be vested in a monetary policy committee (mpc). with the signing of the monetary policy framework agreement (mpfa) between the government of india and the rbi on feb , , flexible inflation targeting (fit) was formally adopted in india. in may , the reserve bank of india (rbi) act, was amended to provide a statutory basis for the implementation of the fit framework. the amended rbi act, also provided that the central government shall, in consultation with the bank, determine the inflation target in terms of the consumer price index, once in every years. accordingly, the central government has notified in the official gazette % consumer price index (cpi) inflation as the target for the period from august , to march , with the upper tolerance limit of % and the lower tolerance limit of %. the amended rbi act, also provides that rbi shall be seen to have failed to meet the target if inflation remains above % or below % for three consecutive quarters. in such circumstances, rbi is required to provide the reasons for the failure, and propose remedial measures and the expected time to return inflation to the target. in , india thus joined several developed and emerging market economies that have implemented inflation targeting. figure shows the timeline for implementation of inflation targeting for countries in this category, starting in . the amended rbi act, provides for a statutory and institutionalized framework for a six-member monetary policy committee (mpc) to be constituted by the central government by notification in the official gazette. the central government in september thus constituted the mpc with three members from rbi including the governor as chairperson and three external members as per gazette notification dated september , . (details of the composition of mpc are given in appendix ). the committee is required to meet at least four times a year although it has been meeting on a bi-monthly basis since october . each member of the mpc has one vote, and in the event of equality of votes, the governor has a second or casting vote. the resolution adopted by the mpc is published after conclusion of every meeting of the mpc. on the th day, the minutes of the proceedings of the mpc are published which includes the resolution adopted by the mpc, the vote of each member on the resolution, and the statement of each member on the resolution. it may be noted that before the constitution of the mpc, a technical advisory committee (tac) on monetary policy was set up in which consisted of external experts from monetary economics, central banking, financial markets and public finance. the role of this committee was to enhance the consultative process of monetary policy by reviewing the macroeconomic and monetary developments in the economy and advising rbi on the stance of monetary policy. with the formation of mpc, the tac on monetary policy ceased to exist. the mpc is entrusted with the task of fixing the benchmark policy rate (repo rate) required to contain inflation within the specified tolerance band. the framework entails setting the policy rate on the basis of current and evolving macroeconomic conditions. once the repo rate is announced, the operating framework looks at liquidity management on a day-to-day basis with the aim to anchor the operating target-the weighted average call rate (wacr)-around the repo rate. this is illustrated in fig. , where the intermediate targets are the short-term and long-term interest rates and the goals of price stability and economic growth are aligned with the primary objective of monetary policy to maintain price stability, keeping in mind the objective of growth. in addition to the repo rate, the instruments include liquidity facility, crr, omos, lending to banks and foreign exchange operations (rbi ). ( ) ( ) primary objective of monetary policy in india is to maintain price stability, while keeping in mind the objective of growth. ( ) definitions of variables are given in appendix it is imperative here to note some of the key elements of the revised framework for liquidity management (rbi ) that are particularly relevant for the operating framework shown in fig. . as noted in the rbi monetary policy report, . • liquidity management remains the operating procedure of monetary policy; the weighted average call rate (wacr) continues to be its operating target. • the liquidity management corridor is retained, with the marginal standing facility (msf) rate as its upper bound (ceiling) and the fixed reverse repo rate as the lower bound (floor), with the policy repo rate in the middle of the corridor. • the width of the corridor is retained at basis points-the reverse repo rate being basis points below the repo rate and the msf rate basis points above the repo rate. (the corridor width was asymmetrically widened on march and april , .) • instruments of liquidity management continue to include fixed and variable rate repo/reverse repo auctions, outright open market operations, forex swaps and other instruments as may be deployed from time to time to ensure that the system has adequate liquidity at all times. • the current requirement of maintaining a minimum of % of the prescribed crr on a daily basis will continue. (this was reduced to % on march , .) the first meeting of the mpc was held in october . between october and march , the mpc has met times. table shows the voting patterns for each meeting with respect to the direction of change in the policy rate, magnitude of change and the stance of monetary policy. table , on the other hand, provides an overall summary of the voting of all the meetings. it is interesting to note in table , that with respect to direction of change/status quo of the policy rate, consensus was achieved in meetings out of . of these meetings, there were three meetings where there were differences in the magnitude of the change voted for although there was consensus regarding the direction of change. the diversity in voting of the mpc members reflects the differences in the assessment and expectations of individual members as well as their policy preferences. to examine if this diversity exists in mpcs of other countries as well, we analyse the voting patterns of countries across the globe during october to march in table . for many countries, we find dissents in some of the meetings, similar to the lack of consensus in some of the meetings of the indian mpc. it merits mention that the committee approach towards the conduct of monetary policy has gained prominence across globe. the advantages of this approach include confluence of specialized knowledge and expertise on the subject domain, bringing together different stakeholders and diverse opinions, improving representativeness and collective wisdom, thus making the whole greater than the sum of parts (blinder and morgan ; maier ). further, rajan ( ) notes that mpc would bring more minds to bear on policy setting, preserve continuity in case a member has to quit or retire, and be less subject to political pressures. maintain neutral - august reduce bps . to . bps reduce bps [ ] maintain . bps [ ] maintain neutral - october maintain . bps reduce bps [ ] maintain neutral - december maintain . bps reduce bps [ ] maintain neutral - february maintain . bps increase bps [ ] maintain neutral - april maintain . bps increase bps [ ] maintain neutral - june increase bps . to . bps maintain neutral - august increase bps . to . maintain . bps [ ] maintain neutral - october maintain . bps increase bps [ ] change to calibrated tightening - december maintain . bps maintain calibrated tightening - reduce bps . to . bps maintain . bps [ ] change to neutral - april reduce bps . to . bps maintain . bps [ ] maintain this section presents a stylized representation of a framework for monetary policy transmission and also applies this framework to india. monetary policy transmission is the process through which changes in monetary policy affect economic activity in general as well as the price level. with note: the decided rates are in bold, the minority votes are italicized, the meetings with changes in stance are underlined developments in financial systems, the world over, and growing sophistication of financial markets, most central banks use the short-term interest rate as the policy instrument for the conduct of monetary policy. monetary policy transmission is thus the process through which a change in the policy rate is transmitted first to the shortterm money market rate and then to the entire maturity spectrum of interest rates covering the money and bond markets as well as banks' deposit and lending rates. these impulses, in turn, impact consumption (private and government), investment and net exports, which affect aggregate demand and hence output and inflation. there are five channels of monetary transmission-interest rate channel; exchange rate channel; asset price channel; credit channel and expectations channel. the interest rate channel is described above. monetary transmission takes place through the exchange rate channel when changes in monetary policy impact the interest rate differential between domestic and foreign rates leading to capital flows (inflow or outflow) which in turn affects the exchange rate and hence the relative demand for exports and imports. transmission through the asset price channel occurs when changes in monetary policy influence the price of assets such as equity and real estate that lead to changes in consumption and investment. a change in prices of assets can lead to a change in consumption spending due to the associated wealth effect. for example, if interest rates fall, people may consider purchasing assets that are non-interest bearing such as real estate and equity. a rise in demand for these assets may result in higher prices, a positive wealth effect and thus higher consumption. further if equity prices rise, firms may increase investment spending. transmission through the credit channel happens if monetary policy influences the quantity of available credit. this may happen if the willingness of financial institutions to lend changes due to a change in monetary policy. further, debt obligations of businesses may also change due to a change in the interest rate. for instance, if the policy rate falls, debt obligations of firms may decrease, strengthening their balance sheets. as a result, financial institutions may be more willing to lend to businesses, thus increasing investment spending. monetary policy changes can impact public's expectations of output and inflation and accordingly, aggregate demand can be impacted via the expectations channel. for instance, expected future changes in the policy rate can impact medium-term and long-term expected interest rates through market expectations and thus affect aggregate demand. further, if inflation expectations are firmly anchored by the central bank, this would imply price stability. a stylized representation of the monetary policy transmission framework of a change in the policy rate is shown in fig. . figure depicts the monetary transmission through the interest rate channel with specific reference to india. (definitions of all variables shown in fig. are given in appendix .) this shows that a change in the policy rate (repo rate) first impacts the call money rate (weighted average call money rate-wacr) and in turn all other money market rates as well as bond market rates including the repo market, certificates of deposit (cd) and commercial paper (cp) markets, treasury bill (t-bill) market, government securities (g-sec) market and the bond market. the lending rate of banks also changes as depicted by the marginal cost of funds based lending rate (mclr). this further impacts consumption and investment decisions as well as net exports and through these, aggregate demand and ultimately the goals of monetary policy. details of the monetary transmission process are given in rbi ( c). the transmission mechanism is beset with lags. as explained in simple terms in rangarajan ( ) , there are two components of the transmission mechanism. the first is how far the signals sent out by the central bank are picked by the banks and the second is how far the signals sent out by the banking system impact the real economy. rangarajan ( ) labels the first component as "inner leg" and the second as "outer leg". to illustrate monetary transmission of the first kind, we examine the impact of a cumulative reduction in the policy repo rate by basis points between february and january . during this period, transmission to various money and bond markets ranged from basis points in the overnight call money market to basis points in the market for -year government securities to basis points in the market for -year government securities. transmission to the credit market was also modest with the -year median marginal cost of funds-based lending rate (mclr) declining by basis points during february and january . the weighted average lending rate (walr) on fresh rupee loans sanctioned by banks fell by basis points while the walr on outstanding rupee loans declined by basis points during february to december . monetary transmission increased somewhat after the introduction of the external benchmark system in october whereby most banks have linked their lending rates to the policy repo rate of the reserve bank. during october to december , the walrs of domestic banks on fresh rupee loans fell by basis points for housing loans, basis points for vehicle loans and basis points for loans to micro, small and medium enterprises (msmes). monetary transmission in various markets is depicted in figs. , and . figure shows the policy corridor with the msf rate as the ceiling and the reverse repo rate as the floor for the daily movement in the weighted average call money rate. the figure shows that the wacr moved closely in tandem with the policy rate (repo rate). figure shows that the g-sec market rates followed the movements in the policy rate. figure shows that the direction of change of mclr was more or less in synchronization with that of the repo rate. the walr for fresh rupee loans tracked the repo rate much more than the walr on outstanding loans. figure shows the % target inflation rate with the ± % tolerance band along with the headline inflation rate. this shows that the headline inflation generally stayed within the band. the average inflation rate from august to march was . % and up to december , it was . %, i.e. close to %. the average gdp growth between q : - and q : - was . % (fig. ). an interesting phenomena, world-wide is the synchronization in the movements in interest rates across the globe. table shows that mpcs in various countries have voted for a cut in their policy rate in at a time when many countries were simultaneously experiencing a slowdown. due to covid- pandemic, in early , some countries have cut the policy rate sharply. this pattern of rate cuts in up to march is almost perfectly aligned with the movements in the repo rate (policy rate) in india. these global patterns are illustrated in figs. and . figure shows that the policy rates for the brics nations moved in tandem from to . figure indicates a similar pattern amongst policy rates of us, ecb, uk and japan. we have so far discussed conventional monetary policy. as already described, monetary transmission of conventional monetary policy entails a change in the policy rate impacting financial markets from short-term interest rates to longer-term bonds and bank funding and lending rates. a change in the policy rate is thus expected to permeate through the entire spectrum of rates that further translates into affecting interest sensitive spending and thus economic activity. however, if there are problems in the monetary policy transmission mechanism or if additional monetary stimulus is required in the circumstances that the policy rate cannot be reduced further (or in addition to a change in the policy rate), then the central banks may employ unconventional monetary policy tools. unconventional monetary measures target financial variables other than the short-term interest rate such as term spreads (e.g., interest rates on risk free bonds), liquidity, credit spreads (e.g. interest rates on risky assets) and asset prices. the objective of unconventional tools is to supplement the conventional monetary policy tools especially in the easing cycle to boost economic growth. in the recent past, rbi has utilized various unconventional tools in addition to conventional monetary policy measures. to better understand the use of accommodative: interest rates stay the same or decrease; tightening: interest rates stay the same or increase: neutral: interest rates can decrease, increase or stay the same table . . large scale asset purchases (also referred to as quantitative easing) by a central bank involve purchase of long-term government securities financed by crediting reserve accounts that commercial banks hold at the central bank. this purchase would lower government bond yields and serve as a signal that the policy rate will stay at a lower level for a longer period. sellers of government bonds may, in turn, change their investment portfolios and invest in more risky assets (e.g., corporate bonds) leading to a decrease in the relevant interest rate and higher asset price and thus boost economic growth. central banks can also purchase assets from the private sector. . lending operations entail provision of liquidity to financial institutions by the central bank through the creation of new or extension of existing lending facilities. this mechanism is different from conventional lending since this is undertaken at looser or specific conditions, e.g., expanding the set of eligible collateral, extending maturity of the loan, providing funding at lower cost and channel/target lending to desired areas or activities with explicit conditions on loans. this lending increases the credit flows to the private sector and helps to restart flow of credit to credit-starved sectors. it can also lead to lower borrowing costs for the financial and real economy sectors. . forward guidance involves central banks communicating future policy intentions and commitments regarding the policy rate to influence policy expectations. forward guidance is given routinely by most central banks. its use as an unconventional tool implies that a central bank uses this to signal that it is open to undertaking extraordinary policy actions for a longer duration. forward guidance can be 'time specific' or 'state specific'. under the former, the central bank makes a commitment to keep interest rates low for a specified period. under the latter, the central bank maintains low rates until specific economic conditions are met. . the rationale of a negative interest rate is that if an interest rate is charged on the reserves that commercial banks hold at the central bank, the banks may be induced to reduce their excess reserves by increasing lending. the first three of these have been applied to india and are reported in table . these include operations twist in december and january as well as april , long-term repo operation (ltro) in february , targeted long-term repo operations (tltro) in march and april , and special refinance facilities to national bank for agriculture and rural development (nabard), small industries development bank of india (sidbi) and national housing bank (nhb) in april . the application of these unconventional monetary tools was necessitated, first by the slowdown in the indian economy in , and second, by the impact of covid- pandemic due to which economic activity and financial markets, the world over, came under severe stress. it was thus necessary for the reserve bank to employ measures to mitigate the impact of covid- , revive growth and preserve financial stability. thus the unconventional monetary policy tools supplemented the conventional monetary policy measures to stimulate growth in the economy. this paper reviews the evolution of monetary policy frameworks in india since the mid- s. it also describes the monetary policy transmission process and its limitations in terms of lags in transmission as well as the rigidities in the process. it also highlights the importance of unconventional monetary policy measures in supplementing conventional tools especially during the easing cycle. at the time of writing (april ), three and a half years have passed since the implementation of the flexible inflation targeting framework and the constitution of the monetary policy committee. with the implementation of fit, india joined the group of various developed, emerging and developing countries that have implemented inflation targeting since . the inflation target specified by the central government was % for the consumer price index (cpi) inflation for the period from august , to march , with the upper tolerance limit of % and the lower tolerance bound of %. as shown in fig. , from august through march , the headline inflation generally stayed within the tolerance band with the average inflation rate slightly less than % during this period. there were episodes of high/unusual inflation due to supply shocks (food inflation, oil prices) but these were suitably integrated in the policy decisions. the monetary policy committee has also been in existence since october . the mandate of the mpc is to set the policy repo rate while taking cognizance of the primary objective of monetary policy-to maintain price stability while keeping in mind the objective of growth-as well as the target inflation rate within the tolerance band. once the policy repo rate is set, the monetary transmission process facilitates the percolation of the change in the policy rate to all financial markets (money and bond markets) as well as the banking sector which further impacts interest sensitive spending in the economy and eventually increases aggregate demand and output growth. in practice, however, there are rigidities as well as lags in the transmission process that impede the speed and magnitude of the transmission and thus question the efficacy of monetary policy with respect to the policy repo rate. nevertheless, the external benchmarking system introduced by rbi from october , whereby all new floating rate personal or retail loans (housing, auto etc.) and floating rate loans to micro and small enterprises extended by banks were benchmarked to an external rate, strengthened the monetary transmission process with several banks benchmarking their lending rate to the policy repo rate. this requirement of an external benchmark system was further expanded to cover new floating loans to medium enterprises extended by banks with effect from april , . this is expected to further improve the transmission process. of course, the policy repo rate is not a panacea for all ills but serves well as a signaling rate. the rbi routinely brings out the statement on developmental and regulatory policies that is released simultaneously with the resolution of the mpc. rbi has also taken recourse to unconventional measures to supplement the conventional tools to boost economic growth. more recently, with the slowdown in followed by the extraordinary slump in economic activity due to covid- pandemic, rbi has been compelled to use rather innovative and unconventional tools starting in december as discussed in table . needless to say, in the unprecedented times of the global pandemic (and, in general, in periods of severe crises), a multi-pronged approach comprising monetary, fiscal and other policy measures is required to protect economic activity and minimize the negative impact of the pandemic (crisis) on economic growth. the importance of monetary-fiscal coordination is highlighted in the resolution of the monetary policy committee dated march , (available on the rbi website) that states the following: "strong fiscal measures are critical to deal with the situation." thus, in addition to monetary policy, fiscal policy has a major role in combating the economic effects of the covid- pandemic. in response to the need of the hour, the government of india has implemented various fiscal measures to provide a boost to the economy. while central banks across the globe have responded to the global pandemic with monetary and regulatory measures, various governments have reinforced the monetary measures by deploying massive fiscal measures to shield economic activity from the effect of the covid- pandemic. a few words about the workings of the mpc are also warranted. as discussed in the paper, the voting pattern of the indian mpc is comparable to international standards, reflecting the healthy diversity in the assessment of the members. the workings of the mpc are transparent with the resolution being made available soon after the end of the meetings. furthermore, each member of the committee has to submit a statement that is made available in the public domain on the th day after the meeting. thus, each member is individually accountable, making the process perhaps more stringent than that of mpcs in other countries. the governor of the bank-chairperson deputy governor of the bank, in charge of monetary policy-member one officer of the bank to be nominated by the central board-member professor, indian statistical institute (isi)-member professor pami dua, director, delhi school of economics (dse)-member; and the three external members have served on the committee since its inception and continue to serve. there have been some changes in the rbi members as follows urjit patel chaired the committee from former deputy governor attended the viral acharya, former deputy governor in charge of monetary policy attended the meetings from deputy governor attended the meetings from michael patra attended all the meetings, first as executive director till december and continues to attend meetings as deputy governor in charge of monetary policy janak raj has attended meetings since february as executive director. references bank for international settlements a hundred small steps: report of the committee on financial sector reforms (chairman: raghuram rajan) state of the art of inflation targeting. handbooks, centre for central banking studies the evolution of inflation expectations in japan. bank of international settlements working papers breaking monetary policy rules in russia the journey of inflation targeting: easier said than done the case for transitional arrangements along the road how central banks take decisions: an analysis of monetary policy meetings the economics of money, banking, and financial markets. pearson: columbia university monetary policy framework in india: experience with multiple-indicators approach changing contours of monetary policy in india. mumbai: reserve bank of india bulletin i do what i do the new monetary policy framework-what it means monetary policy operating procedures in emerging market economies report of the committee to review the working of the monetary system (chairman: dr. sukhamoy chakravarty) report on currency and finance - : fiscal-monetary co-ordination report of the expert committee to revise and strengthen the monetary policy framework (chairman: dr. urjit patel) report of the internal study group to review the working of the marginal cost of funds based lending rate system (chairman: dr. janak raj) forex market operations and liquidity management (by-janak raj, sitikantha pattanaik, indranil bhattacharya and abhilasha) report of the internal working group to review the liquidity management framework governor's statement, sixth bi-monthly monetary policy statement governor's statement, seventh bi-monthly monetary policy statement monetary policy transmission in india-recent trends and impediments (by-arghya kusum mitra and sadhan kumar chattopadhyay). reserve bank of india bulletin monetary policy report, april. mumbai. reserve bank of india. ( e) reflections on analytical issues in monetary policy: the indian economic realities publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations acknowledgements i am grateful to michael patra and janak raj, deputy governor and executive director respectively, reserve bank of india for useful and constructive suggestions. i also gratefully acknowledge help and support from hema kapur, deepika goel and neha verma, teachers in colleges of the university of delhi, who also motivated me to write in a student-friendly manner. special thanks are due to naina prasad for competent and diligent research assistance. i am grateful to the editors of the indian economic review for inviting me to contribute to the newly instituted section on policy review. earlier versions of this paper were presented as a public lecture at the delhi school of economics in march and as a keynote address at the annual conference of the indian econometric society at madurai kamaraj university in january . i am grateful to the participants of these events for their feedback. repo rate is the (fixed) interest rate at which the rbi provides overnight liquidity to banks against the collateral of government and other approved securities under the liquidity adjustment facility (laf) reverse repo rate is the (fixed) interest rate at which the rbi absorbs liquidity, on an overnight basis, from banks against the collateral of eligible government securities under the laf liquidity adjustment facility (laf) enables the rbi to modulate short-term liquidity under varied financial market conditions to ensure stable conditions in the overnight (call) money market. the laf operates through daily repo and reverse repo auctions thereby setting a corridor for the short-term interest rate consistent with policy objectives corridor is determined by the msf rate as ceiling and reverse repo rate as the floor of the corridor for the daily movement in the weighted average call money rate marginal standing facility (msf) is the facility under which scheduled commercial banks can borrow additional amount of overnight money from the rbi at a penal rate against eligible securities. banks are allowed to dip into their statutory liquidity ratio (slr) portfolio to borrow funds under this facility up to a limit decided by the rbi. this provides a safety valve against unanticipated liquidity shocks to the banking system bank rate is the standard rate at which the rbi is prepared to buy or rediscount bills of exchange or other commercial papers eligible for purchase under the reserve bank of india act, cash reserve ratio (crr) is the minimum cash balance that a scheduled commercial bank is required to maintain with the rbi as a certain percentage of its net demand and time liabilities (ndtl) relating to the second preceding fortnight. it is prescribed by rbi from time to time statutory liquidity ratio (slr) is the share of ndtl that the scheduled commercial banks are required to maintain on a daily basis in safe and liquid assets, such as unencumbered government securities and other approved securities, cash and gold open market operations (omos) are conducted by the rbi by way of sale/ purchase of government securities to/ from the market with an objective to adjust the rupee liquidity conditions in the market on a durable basis market stabilization scheme (mss) was introduced as an instrument for monetary management in april . surplus liquidity of a more enduring nature arising from large capital inflows is absorbed through sale of short-dated government securities and treasury bills. the cash so mobilized is held in a separate government account with the rbi monetary base (reserve money/m ) = currency in circulation + bankers' deposits with the rbi + 'other' deposits with the rbi m = currency with the public + demand deposits with the banking system + 'other' deposits with the rbi m = m + saving deposits of post office saving banks call money rate is the rate at which overnight money are lent and borrowed in the money market weighted average call money rate (wacr) is volume weighted average of rates at which overnight money or money at short notice (up to a period of days) are lent and borrowed in the money market. this weighted average rate can be computed for any period such as, daily, weekly, yearlyrefinance facility under monetary targeting framework was provided by rbi as an additional source of reserves. the two types of refinance facility provided to banks include export credit refinance (extended against bank's outstanding export credit eligible for refinance) and general refinance (provided to banks to tide over their temporary liquidity shortages) (excluding rrbs, payment banks and small finance banks) on the outstanding rupee loans and fresh rupee loans sanctioned by the banks. it is based on lending rates to different sectors with weights based on credit extended to different sectors money market: market for lending and borrowing of short-term funds which are highly liquid. it covers money and financial assets that are close substitutes for money including call money, repo, tri-party repo, t-bills, cash management bills, commercial paper and certificate of deposit call money market: instrument: overnight money and money at short notice (up to a period of days) is lent and borrowed without collateral. call money is liquid and can be turned into money quickly at low cost and provides an avenue for equilibrating the short-term surplus funds of lenders and the requirements of borrowers borrowers: scheduled commercial banks (excluding rrbs), co-operative banks (other than land development banks), and primary dealers (pds) lenders: same as borrowers market repo: instruments: repurchase agreement (repo) which is used for borrowing funds by selling securities with an agreement to repurchase the said securities on a mutually agreed future date at an agreed price which includes interest for the funds borrowed. government securities, cps, cds, units of debt etfs, listed corporate bonds and debentures are eligible securities for repo. repo against corporate bonds are called repo in corporate bond participants: banks, pds, mutual funds, listed corporates, all india financial institutions, any other entity approved by the rbi tri-party repo market: instrument: tri-party repo, a repo contract where a third entity (apart from the borrower and lender), called a tri-party agent, acts as an intermediary between the two parties to the repo to facilitate services like collateral selection, payment and settlement, custody and management during the life of the transaction participants scheduled commercial banks, recognized stock exchanges and clearing corporations of stock exchanges or clearing corporations authorized under pss act and any other entity regulated by rbi or sebi are eligible subject to certain criterion. all the repo market eligible entities are permitted to participate in tri-party repo market instrument: short-term debt instruments issued by the goi and sold by rbi on an auction basis. treasury bills are zero coupon securities that pay no interest, issued at a discount and redeemed at the face value at maturity. they are currently issued in three tenors, namely, days, days and days. they are also traded in the secondary market investors: any person resident of india, including firms, companies, corporate bodies, institutions and trusts along with non-resident indians and foreign investors (subject to approval by government) can invest through a competitive route certificate of deposits market: instrument: a negotiable money market instrument issued in dematerialized form or as a usance promissory note against funds deposited at a bank or other eligible financial institution for a specified time period. maturity ranges from days to years. cds can be traded in the secondary market issuers: banks and financial institutions investors: individuals, corporations, companies (including banks and pds), trusts, funds, associations and non-resident indians (but only on non-repatriable basis) commercial paper market: instrument: an unsecured money market instrument issued in the form of a promissory note. they are issued for the maturities between a minimum of days and a maximum of up to year from the date of issue (given that the credit rating of the issuer is valid in the period). cps can be traded in the secondary market issuers: corporates, pds and all india financial institutions (fis) investors: individuals, banks, other corporate bodies (registered and incorporated in india), non-resident indians, bond market: instrument: a debt instrument whereby an investor loans money to an entity (typically corporate or government) which borrows the funds for a defined period of time at a variable or fixed interest rate. bonds are used by companies, municipalities, states and sovereign governments to raise money to finance a variety of projects and activities issuers: government or corporates investors: banks, mutual funds, foreign institutional investors, provident funds, pension funds government securities market: instrument: a tradable instrument issued by the central or the state governments. it acknowledges the government's debt obligation. securities issued by state governments in india are known as state development loan (sdl). the short-term g-secs (treasury bills) have original maturities of less than year while long-term g-secs (government bonds or dated securities) have original maturity of year or more. there is an active secondary market in g-secs participants: commercial banks, pds, institutional investors like insurance companies, other banks including cooperative banks, regional rural banks, mutual funds, provident and pension funds, foreign portfolio investors (allowed with quantitative limits prescribed from time to time), and corporates instrument: debt securities issued by private and public corporations. companies issue corporate bonds to raise money for a variety of purposes, such as building a new plant, purchasing equipment, or growing the business. the stock exchanges have a dedicated debt segment in their trading platforms to facilitate the needs of retail investors. a corporate bond is generally priced on the basis of price of g-sec of comparable tenure with a spread added to it. they are also traded in secondary market participants: corporates, banks, retail investors and institutional investors including insurance companies and mutual funds, foreign investors the gazette notification of the ministry of finance dated september , notes the following. "in exercise of the powers conferred by section zb of the reserve bank of india act, act, ( of , the central government hereby constitutes the monetary policy committee of the reserve bank of india, consisting of the following, namely: key: cord- - z jyzd authors: matzinger, p.; skinner, j. title: strong impact of closing schools, closing bars and wearing masks during the covid- pandemic: results from a simple and revealing analysis date: - - journal: medrxiv : the preprint server for health sciences doi: . / . . . sha: doc_id: cord_uid: z jyzd many complex mathematical and epidemiological methods have been used to model the covid- pandemic. among other results from these models has been the view that closing schools had little impact on infection rates in several countries . we took a different approach. making one assumption, we simply plotted cases, hospitalizations and deaths, on a log y axis and a linear date-based x axis, and analyzed them using segmented regression, a powerful method that has largely been overlooked during this pandemic. here we show that the data fit straight lines with correlation coefficients ranging from % - %, and that these lines broke at interesting intervals, revealing that school closings dropped infection rates in half, lockdowns dropped the rates to fold, and other actions (such as closing bars and mandating masks) brought the rates even further down. hospitalizations and deaths paralleled cases, with lags of three to ten days. the graphs, which are easy to read, reveal changes in infection rates that are not obvious using other graphing methods, and have several implications for modeling and policy development during this and future pandemics. overall, other than full lockdowns, three interventions had the most impact: closing schools, closing bars and wearing masks: a message easily understood by the public. other, more commonly used plots, most of which are plotted on linear y axes - or, at best, on axes of log (ref ) . because the total number of covid- cases ( figure a , solid green line) tended to increase exponentially, resulting in a fairly straight line on the log scale, we were able to determine from the slope (dashed green line) that the initial doubling time was . days. this rapid rate lasted until march , at which time it slowed to a doubling time of . days. this change occurred days after schools closed, days after bars and restaurants closed, and one day before the state lockdown, suggesting that the effect of one or both of the first two policy decisions was to reduce the doubling rate of cases to slightly more half of the original rate. figure b shows that the slopes for hospitalizations and deaths followed the same pattern, with lag times of about three and eight days longer respectively than the lag times of positive cases. figure c shows the effect of the lockdown in md, which was followed twelve days later by an additional threefold change in doubling time, from . to . days, and similar rate reductions in hospitalizations and deaths with additional lags of and days respectively. segmented regression analysis showed that the combined broken lines fit the data remarkably well, with r values well over for total cases ( . ), for total hospitalizations ( . ) and total deaths ( . ) . figure d shows the data for daily new cases, whose slopes tend to change within a day of those for total cases, and undergo greater changes. then, days after schools, bars & restaurants are closed (and one day before lockdown), the doubling rate slows to every . days. b) other parameters also drop. hospitalization and death rates drop, and days respectively after the decline in cases. c) nd rate drop: the lockdown is followed by a second rate decline to a doubling time of . days, for cases, hospitalizations and deaths at , and days later respectively d) new daily cases: new cases, new hospitalizations and new deaths follow similar patterns. the data are less smooth, partly due to the smaller numbers and partly because reporting is lower on sundays and mondays (brown arrows) and rebound later in the week. for use under a cc license. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . the fact that the inflection points for daily new cases often occur one day before those for total cases, rather than on the same day, and that the correlation coefficient value ( . ) is slightly lower than that for total cases, is likely due to the fact that daily new cases have a periodic dip on sundays and mondays, and then rebound slightly as the reporting catches up during the week. this variability results in a greater "fuzziness" that creates an uncertainty in the break points and a somewhat lower accuracy in the slopes. nevertheless, the high correlation coefficients suggest that these slopes are good representations of the trends in the data. because maryland closed bars and restaurants just three days after closing schools, it was impossible to separate the effects of those two actions from each other. a recent study on closing schools ran into the same problem. in fact, the near simultaneous execution of several different interventions by many states and countries has made it difficult to assess the value of any one particular intervention. we therefore asked if any state had witnessed changes in slopes after closing schools but before taking any other major action, such as closing bars and restaurants, closing essential businesses, or giving "stay at home" orders. we found three states with no mask mandates (georgia, tennessee, mississippi), that had spaced their other interventions far enough apart to enable us to examine the effects of each by itself. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint submitted manuscript: confidential by a second change to a doubling time of . days. two days after this second rate drop, the governor ordered a lockdown , which was followed by a third decline in the slopes after a lag of nine days. the observation that each change in doubling times occurred before the next government intervention suggests that each intervention is followed by its own rate change and that additional interventions have additional effects. two days after this second rate drop, the governor ordered a lockdown , which was followed by a third decline in the slopes, after a lag of nine days, to a doubling time of . days. the observation that each change in doubling times occurred before the next government intervention suggests that each intervention is followed by its own rate change and that additional interventions have additional effects. tennessee ( figure b ) also closed schools on march th and saw a twofold drop days later, the same day that bars, restaurants and non-essential business were closed. this second intervention was followed eleven days later by another twofold drop in rate. one day after this second drop, the governor issued a "stay at home" order , which correlated with a third drop days later. mississippi ( figure c ) was a puzzle at first, because the first rate drop occurred only two days after the official order to close schools . rather than dismiss this as a simple outlier -it was the only state among the that had such a short lag time -we delved into other possible explanations, thinking that perhaps we were simply wrong, and some aspect of human behavior other than school closings was responsible for the first sets of rate reductions. perhaps, americans had simply started going out less, as suggested by the phone mobility data from apple, google and cuebiq - . however, an analysis of the mobility data for mississippi in comparison with other states (supplemental figure ), showed no change in mobility that could underlie mississippi's early rate change. we therefore looked for other factors, and discovered that spring breaks for mississippi colleges and k- schools had almost all begun earlier than other states, with slightly variable start dates from march to march . although the k- breaks normally last only one week, the governor asked schools to extend their spring breaks because of the virus , and nearly all of the schools did not go back into session before he officially closed them on the th of march , . consequently, the drop in the rate of cases that occurred on march th most likely resulted from the fact that children had stopped attending school - days earlier, rather than from the march th executive order to close schools. thus, for states that separated their government actions by a week or more, we were able to assess the effects of those actions individually. closing schools appeared to cut the rate of infections in half, beginning - days post-closure, and similarly reduced hospitalizations, but with lag times - days longer than for positive infections. deaths followed suit, lagging an additional - days. closing bars and restaurants and ordering lockdowns similarly reduced the rates of infections, with similar lag times. cumulatively, these interventions resulted in - fold drops in the rates of infections, hospitalizations and deaths. nevertheless, even when combined, these effects were frequently insufficient to result in a steady decrease in the daily tallies of new infections. for that we needed masks. although the federal government never mandated masks, and many government officials continued to eschew them, a few state governors wrote orders for their constituents to wear for use under a cc license. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint masks. unlike school closings, which occurred all over the us in the space of about two weeks, from march (mississippi) to march rd (idaho), mask mandates were put in place over a longer time period, from march to july. this gave us an opportunity to evaluate both early and late mandates. we found that they were about equally effective (figures and ) . figure shows the effects of early mask mandates from four states that ordered the use of masks at times spanning a month, from april th to may th . we depict new daily numbers, as total numbers were high enough by this time to be slow to show intervention effects. each state's mandate was followed by a drop in the rates of infections, and then by drops in the rates of hospitalizations (where reported) and deaths, showing that the effect of mandating masks is to drop the slopes about fold. as the mandates stepped through time, the rate reductions followed in concert, with later mandates correlating with later inflection points. this supports the view that these rate reductions were due to wearing masks, rather than other potential changes in mobility - or behavior. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint the lag times for the effect of masks ( - days, as indicated by dark blue bars near the x axis) seemed somewhat longer than those that followed closing schools, bars and restaurants, or ordering lockdowns, perhaps because it takes time for people to obtain masks and get into the habit of wearing them, whereas a school or a business can be closed in a day. an exception to the effectiveness of mask wearing was seen in new york, which implemented a mask mandate during its lockdown, when new daily cases were already being cut in half every as states reopened their economies, and experienced surges in new infections, we found that the new infection rates showed the effects of previous interventions that remained operational, as well as clear effects of interventions that were implemented later. for example, figure shows data for four states (texas, arizona, florida and georgia) that opened in the middle of may. we chose these four because they had not previously mandated masks, in order to determine the effect of late mask mandates. these states had flattened or even reversed their slopes by closing schools, bars and restaurants, and non-essential businesses. all but georgia had also implemented strict stay-at-home orders ( figure a -c) the first effect we observed was the lasting impact of school closings. as infection rates surged following reopening of state economies, the benefit from having closed the schools persisted. in all four states, as schools remained shuttered for the summer, the rates of new infections never recouped the initial doubling times of - days, instead returning to the slower doubling times of - days that had followed the school closings, despite the fact that all other restrictions had been lifted. this suggests that the effect of each intervention endures as long as that intervention remains place, regardless of other actions that may be implemented or rescinded. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint submitted manuscript: confidential the second thing we noticed was that the post-opening surges seemed to be strongly correlated with the opening of bars. regardless of the timing or sequence of other relaxations, opening bars was followed - days later by surging infection rates. texas, for example ( figure a ), opened many businesses, including restaurants from may st to may th , with little repercussions on infection rates. on may nd , bars were opened (along with aquariums, zoos, rodeos, bowling alleys, bingo halls and skating rinks) and days later, infection rates surged. arizona ( figure b ) opened everything over an day period, with bars opening only on the last day (may th ). as with texas, arizona's surge of new cases also began days later. georgia ( figure d ) carefully opened its economy over a period of more than a month, with no ill effects until it opened bars on the last day, along with amusement parks and overnight camping. it saw a surge starting days later. in florida each county decided individually when to open, making it impossible to determine the effect of opening bars in the sunshine state, but for the other three states, the lag from opening bars to surges in infection rates was remarkably consistent ( - days), with only day's difference among the three. thirdly, the data suggested that the simple combination of closing bars and wearing masks was a highly effective way to clamp down on surging infection rates. each of these measures brought the infection rates down by twofold, for a cumulative reduction of fourfold in new infection rates. states that implemented both interventions, put surging infection rates into decline. texas, arizona and florida (figure a-c) all carried out both interventions, though in different orders. in all three states, surging doubling times of - days sank to halving times ranging from (arizona) to (texas) days. in contrast to the other three surging states, georgia's governor neither closed bars nor mandated masks (figure d) . however, he did encourage mask wearing, and several mayors mandated them for their cities, covering about % of the state's population. this mask mandate was followed about ten days later by a twofold reduction in the rate of new cases. nonetheless, new cases did not go into decline, but instead flatlined. the major difference between georgia and the three states that dropped their post-opening surge rates to declining ones is that the more successful states not only mandated mask wearing, they also closed their bars. together the data from these four states suggest that bringing cases down to manageable levels might not require shutting down an entire economy. the combination of closing schools, closing bars, and wearing masks may be enough. as countries and states debate the best way to prevent covid- infections, and as they contemplate re-opening schools in the fall, the analysis of the information thus far gleaned about this new pandemic is vital to those decisions. there have been several previous attempts to correlate various government interventions with rates of sars-cov- infections, and predict which might be most effective [ ] [ ] [ ] [ ] [ ] [ ] . these studies, however, have mostly taken a global view, and this is not necessarily the most productive for the us. although a global view has the advantage of large numbers, it has the disadvantage of combining disparate interventions, done at different times in different places, into one global soup, in an attempt to find common themes. we honed down instead to the granular data at the state -and sometimes city -level, painstakingly combing governors' executive orders and press releases (and those of mayors when necessary) to find examples of states that had implemented each of their interventions sufficiently far apart to enable us to distinguish the effect(s) of each individual intervention. for use under a cc license. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint a second difference between this and previous studies is the method we used. a maxim among scientists is to use the simplest method that explains the data. our decision to plot the data, as they came, without any assumptions, on a log y axis, allowed us to see the straight lines in the data, find the slopes of those lines, and the inflection or "break" points where those slopes changed. the human eye, coupled with human intuition is a powerful tool, and can guide a simple mathematical approach. we therefore used segmented regression analysis to test our visually-based hypotheses about breakpoints, slopes and doubling times. the high r values for the segmented slopes highlight the accuracy of the visually based breakpoints, despite the variability of the data of new daily cases known to occur because of the "weekend effect" of low reporting, and of low initial numbers. the results, demonstrate that, other than full lockdowns, three government interventions had the most impact on the rates of covid- infections: closing schools, closing bars and wearing masks. schools: closing schools not only flattened the early curves of rapidly rising numbers of infections in march (figure ), it prevented a return to those initial rates after states opened up their economies in mid-summer -a time when schools remained closed (figure ). this demonstrates that the effect of a particular intervention lasts as long as that intervention is in place, regardless of other interventions that might be mandated and/or rescinded. although it could be argued that the mid-summer surging rates of infections were lower than the initial rates in march because of increased resistance in the us population, this is unlikely. at the time (early to mid-june), the number of confirmed cases in the us -just under millionconstituted a mere . percent of the population . even if the true infection rate were - times higher, as underscored by a recent study , the increase to % would still be too small to account for the reduced rates of post-opening infections, which closely mimicked the early post-school-closing rates. these findings help to resolve the conflicting conclusions of two previous reports. in contrast to two early predictive models suggesting that closing schools would bring down covid- infection rates, a study covering the effects of government interventions in six countries concluded that closing schools had no effect in the us. however, the authors analyzed each of those countries as a whole, which is not useful in the case of the us, which had no national policy on the matter. the second study analyzed individual states, and concluded that closing schools had a major impact. however, in evaluating all the states together, the authors noted that they were unable to discount the potential effects of other interventions. our study, like theirs, shows that closing schools had a major effect, and supports this idea with the results from the small set of states (figure ) , where the effect could not be explained by other interventions. bars: the effect of closing and opening bars became evident in those states that opened their economies in stages (figure ) . although most states closed bars and restaurants simultaneously during their early shutdowns, some opened them at different times during the re-openings. we found that, regardless of other relaxations, new infections surged beginning - days after bars were opened, and fell once again about days after bars were re-shuttered. this suggests that closing (and re-opening) settings that might not be conducive to social distancing has more impact on new infection rates than would opening other types of businesses (dog groomers, markets, hardware stores; even restaurants). masks. akin to school closings, the beneficial effect of wearing masks was evident during the early period when states were closing down (figure ) , and also later during post-opening surges. under for use under a cc license. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint both conditions, those states that mandated masks saw about a twofold reduction in the rate of new cases. although political controversy reduced the proportion of the population that wears masks, those states that combined masks with bar closures saw their post-opening surge rates drop to declining ones (figure ) . we surmise that better adherence to the mask mandates would likely have generated even larger decreases in infection rates. one exception to the effect of early mask mandates was evident in the data from new york (supplemental figure ) , which mandated masks after it had already turned its rapidly rising infection numbers into declining ones. the mask mandate had no further suppressive effect on infections. however, when new york later opened its economy, and infections began to rise, that increase was remarkably lower than those of states that opened without mask mandates in place (figure ), suggesting that the early mask mandate had a long lasting effect. several studies suggested that early interventions have more effect than later ones. however, our data show that late interventions can be just as effective as early ones. compare, for example, the twofold reductions in infection rates that follow early mask mandates in figure , with the similar reductions seen in figure -with mandates made months later. although the numbers of cases at the time of a late intervention may be larger, setting a higher baseline, the proportional rate reductions are about the same. whether flattening a curve at or new cases per day, these interventions have a major effect that can lead, with time, to lowering infections to the same level. finally, figures - show that rates of new daily hospitalizations and new deaths seem to parallel those of new cases, with lag times of about three days to a week for hospitalizations, and a further lag of - days for deaths. although improvements in medical care may start to change this picture [ ] [ ] [ ] , it currently appears that a fairly constant proportion of infected people will become ill and die. to counter this, we need a global set of effective policies to reduce new infections, as reductions in hospitalizations and deaths will follow. in the absence of a uniform us federal policy, we have been able to use the different state policies to determine the value of different interventions. our analysis shows that, when combined, the three most powerful interventionsclosing schools, closing bars and wearing masks -successfully flattened initial infection rates, and turned post-opening surges into declining ones, suggesting that the country could perhaps open up its economy safely if it kept bars and schools closed, and required the strict wearing of masks in public coda: if, in a future pandemic with a new infectious agent, governing bodies decide to base decisions on analyses of rates of infections, hospitalizations and deaths, we will need to eliminate the weekend effect, which results in underreporting on weekends and mondays, and over-reporting later in the week, in every state examined. this can delay the determination of a rate change for a week or more, because many data points must accumulate to reliably assign a breakpoint and new slope. as there is already a biological delay from infection to the onset of symptoms, and a further delay before testing, any additional delay prevents the timely implementation of needed interventions. in a rapidly evolving pandemic, reliable data are crucial to the outcome, and every day counts. for use under a cc license. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . references this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint ) statista covid https://www.statista.com/topics/ /the-coronavirus-disease-covid- -outbreak/ ) ihme http://www.healthdata.org/covid ) git hub. (https://github.com/covid statepolicy/socialdistancing) ) muggeo,vmr estimating regression models with unknown break-points statistics in medicine volume creative commons cc by-nc- . license, from statista and from the ihme . for school closings, mobility data, and other government actions, we also relied on github and then verified the dates with the various governors' orders. if the date of official school closing was a monday, we used the saturday before as the first date that students were not in school. for mississippi, we found that colleges and universities, and most k- districts had gone on spring break about a week and a half before the official governor's order to close the schools. we contacted the mississippi department of education, and most of the individual school districts, to find which, if any, had gone back to school in the interim between spring break and the official closing order, covering . % of students in the state, and discovered that > % of those students had not gone back to school, mostly because of local decisions by their mayors, school boards or boards of health. we consequently used the first day of spring break as the date of school closing in mississippi. for deaths, we report the combined "confirmed plus probable" when available. for use under a cc license. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . data were analyzed in two ways. first by visualization on a plot using a log y axis to find the approximate dates of breakpoints in the lines. second, using segmented linear regression to find and estimate the breakpoints, and to compute regression slopes and confidence intervals. to this end, trends in the number of new cases, total cases and total deaths were estimated by segmented regression using the "segmented" package library in r following its authors instructions . the independent variable (x) was always "number of days" starting from march rd as day . march rd was chosen because none of the states examined had any covid- cases, hospitalizations or deaths reported prior to march rd . initial values for either or segment breakpoints were provided using the rd , th , and th percentiles of date numbers spanning the range of the total deaths reported from that particular state. total deaths were chosen because they typically had the smallest range of dates, so initial values chosen from the range of total deaths would usually work for the positive cases and the hospitalizations. if only breakpoints were needed, then only rd and th percentiles were used. in rare cases where these initial values would not work to fit a particular variable (e.g. hospitalization or new cases), initial values would be chosen manually based on the date range of that variable. estimated breakpoints were generally robust to the initial values chosen, and would typically yield the same estimated breakpoints even when substantially different initial values were provided. estimated breakpoints were reported in number of days with their standard errors and their predicted date. slopes for the resulting or regression segments were also reported with their adjusted % confidence intervals and their doubling times, calculated as /slope. the % confidence intervals can be compared against zero, to determine if slopes are increasing or decreasing, and they can be compared against each other to determine if one slope has significantly flattened or significantly increased relative to the previous slope. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint ______________________________________________________________________ supplemental figure ) new york new daily cases and deaths: pink, orange and purple arrows point respectively to st , nd , rd inflection points found during early stages of pandemic. larger red arrows point to inflection points during the state's economic openings. question marks indicate slope and inflection point where the estimate is questionable because of lack of sufficient data points. ) things to note from supplemental figure : ) closing schools, restaurants and bars dropped the infection rate about four fold, seemingly a combination of the individual effects of closing bars and closing schools seen in states that ordered those separately. ) the effect of closing schools eateries is as strong here, at a time when daily new infections were close to a thousand, as they were in other states with daily new infection rates in the tens, supporting the idea that the proportional effect of a particular mandate is about the same whether implemented early or late. ) as with other states, opening the economy stopped the decline in infections. opening in stages resulted in staged increases in slope. ) mandating masks had no apparent immediate effect during the lockdown, as the previous mandates had already sent infection rates into decline. however, when the state opened up, it did not return to the post-school closing doubling rate of . days, as was seen in states that had not required masks (figure ), but instead to the lower rates that resulted from late-post-opening mask mandates. thus, like the effect of closing schools, the effect of mandating masks seems to last as long as the mandate is in place. phase = other personal services (indoor dining postponed) things to note: ) closing schools, restaurants and bars dropped the infection rate about four fold, seemingly a combination of the individual effects of closing bars and closing schools seen in states that ordered those separately. ) as with other states, opening the economy stopped the decline in infections. opening in stages resulted in staged increases in slope. ) mandating masks had no apparent immediate effect during the lockdown. however, when the state opened up, it did not return to the post-school closing doubling rate of . days, as was seen in states that had not required masks (figure ), but instead to the lower rates that resulted from late-post-opening mask mandates. thus, like the effect of closing schools, the effect of mandating masks seems to last as long as the mandate is in place. for use under a cc license. this article is a us government work. it is not subject to copyright under usc and is also made available preprint (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this this version posted september , . . https://doi.org/ . / . . . doi: medrxiv preprint behaviour and the transmission of close contact infections in eight european countries changes in contact patterns shape the dynamics of the covid- outbreak in china science idris guessous, seroprevalence of anti-sars-cov- igg antibodies in geneva, switzerland (serocov-pop): a population-based study. the lancet v tiffany wu the effect of large-scale anti-contagion policies on the covid- pandemic association between statewide school closure and covid- incidence and mortality in the us jama published online states with masks inhibition of bruton tyrosine kinase in patients with severe covid- the lancet author links open overlay ivan fan-ngaihung dexamethasone in hospitalized patients with covid- -preliminary report nejm july , doi: . /nejmoa ) covid tracking project we thank tim d. blood of the maryland department of health for pulling and cleaning data, gabrielle bains and yvonne rosenberg for scientific and editing suggestions, the science writer, david c. holzmann for improving flow and clarity, mihalis lionakis and robert munford for critical review, and steve holland for support, insightful questions and occasional butt kicks. key: cord- -rsp rx authors: teixeira da silva, jaime a.; tsigaris, panagiotis title: policy determinants of covid- pandemic-induced fatality rates across nations date: - - journal: public health doi: . /j.puhe. . . sha: doc_id: cord_uid: rsp rx abstract objectives covid- is the most devastating pandemic to affect humanity in a century. in this paper, we assessed tests as a policy instrument and policy enactment to contain covid- and potentially reduce mortalities. study design a model was devised to estimate the factors that influenced the death rate across nations and by income group. results nations with a higher proportion of people age + had a higher fatality rate (p = . ). delaying policy enactment led to a higher case fatality rate (p = . ). a % delay time to act resulted in a . % higher case fatality rate. this study found that delaying policies for international travel restrictions, public information campaigns, and testing policies increased the fatality rate. tests also impacted the case fatality rate, and nations with % more cumulative tests per million people resulted in a . % lower mortality rate. citizens of nations who can access more destinations without the need to have a prior visa have a significant higher mortality rate than those that need a visa to travel abroad (p = . ). conclusion tests, as a surrogate of policy action and earlier policy enactment, matter for saving lives from pandemics as such policies reduce the transmission rate of the pandemic. million people, causing , mortalities globally. the majority of deaths have occurred in the + age group, most having medical preconditions. , policies for social distancing, lockdowns, testing, isolating and tracking are necessary to contain the spread of the virus, although they come with a cost of an economic recession with its negative side effects. here, we assessed tests as a policy instrument and the start of policy enactment to contain and potentially reduce mortalities across nations. to achieve this, a cross-sectional ecological study was conducted for numerous nations around the world, and a model was estimated to explain the pattern of the crude case fatality rate (cfr) as of july . the objective was to estimate, using regression analysis, the direction and strength of the association between the death rate, as the response variable, controlling for: high-income nations conducted significantly more tests per million people than the other two income groups, (i.e., . and . times more than upper-middle income and low-income nations, respectively). in smoking prevalence and covid- in europe estimating case fatality rates of covid- key: cord- -triub h authors: ibraheem jabbar, shaima title: automated analysis of fatality rates for covid across different countries date: - - journal: nan doi: . /j.aej. . . sha: doc_id: cord_uid: triub h one of the significant parameters that helps in the reporting the highest risk areas, which have covid pandemic is case fatality rate (cfr). in this work, automated analysis was carried out to evaluate fatality rate (cfr) across different countries. furthermore, a state of art algorithm is proposed to estimate cfr and it is possible to make it applicable in the mobile phone. this application will enable us to monitor the status level of the patients (suspected, exposed and infected) to save time , efforts and get a high quailty of the recordings. all data were obtained from (https://www.worldometers.info/coronavirus/) and pointed at the period between th march and th may, . results present spain and egypt have a highest score of the fatality rate (approximately %) compared with previous research, which italy was the highest score of the case fatality rate (cfr). on the other hand, australia has had the lowest of the (cfr) in the current and previous researches. furthermore, spain has the highest percentage score of the total active cases and death rate: . % and . % respectively. documentation and comparison fatality rate of covid pandemic across different countries could assist in illustrating the strength of this pandemic, speed spreading and risk area which infected of this disease. covid- , also known as the coronavirus disease , is an infectious disease that transmitted from animal to human. the first case was discovered at wuhan city, china, in december and spread worldwide to most countries. the first identified case was reported in december and since then it has spread rapidly. the virus causes a range of the symptoms, from fever, coughs, sore throats, headaches with difficulty in breathing and sometimes death more severe cases [ ] , [ ] , covid- spreads by droplets of saliva from the nose and mouth of an infected person to healthy contacts. also contact with contaminated hard surfaces could transmitted the infection as the virus will survive up to - days on hard objects. if a person, who is infected with the coronavirus, comes into close contact with another person, it is likely that that person will become infected. furthermore, droplets of saliva that are ejected out of the mouth and the nose when sneezing or coughing. it may contain the virus, and will allow the virus to spread if it lands on surfaces where it could stay for up to five days [ , , , ] . despite continues efforts by many nations, the fatality rate for covid- is still souring as the virus spread through air born and airdropped. however, banning large crowds and practicing social-distancing are able to slow its spread and avoid exposure to higher viral load. quarantine could reduce the incidence rate of covid- and lower the fatality rate [ ] , [ ] , [ ] . fatality rate is a metric, which has been used to evaluate the covid- effects on human by measuring the ratio between the total number of dead to total number of closed cases (the number of dead patients with the number of recovered patients) [ ] , [ ] , [ ] . in order to report a realistic worldwide fatality rate, many problems were addressed. firstly, the lack of necessary laboratory test for all covid- patients. secondly, the hessite of some covid- patients to report their illness to the hospital. there are many problems in obtaining the honest real values of the fatality rate. this is due to the lack of the capabilities to carry out the necessary laboratory tests for all people who's have virus symptoms to detect the virus and sometimes hesitation of patients to go hospital when they feel virus symptoms. many researches have been concerned with calculating or estimating the fatality rate because coronavirus has become a global pandemic and its importance in analysis of virus impact. in the first article, predicting mortality rate has been performed based on using machine learning tool [ ] and deep learning [ ] . this gives an efficient procedure in identifying mortality rate shortly and accurately. construction a mathematical model to represent lockdown of covid- has been introduced and applied [ ] . this model illustrates three types of quarantine. optimization of this model based on the analysis of all conditions, which impact on the spreading and could reduce the number of the infected people. moreover, a real time mathematical model has been carried out to detect fatality rate of severe cases of covid- [ ] . it is very powerful to involve this algorithm, but in the same time it has a kind of complexity to make it applicable for all people. the rapid increase in the number of covid- cases adversely affects the quality of the healthcare services, which provided by hospitals. therefore, presenting an early plan to assess patient's stage of covid- could support in decreasing the pressure on other healthcare services and help to decide patient priorities. in this research, we conducted a study to calculate the fatality rate for the period between th march and th may, across different countries (usa, spain, italy, iraq, iran, uzbekistan, egypt and australia) based on the data which were collected from [ ] . in addition, in this work a novel and flexible algorithm has been proposed and it is likely to be applicable on the mobile phone for everyone to improve the performance of the fatality rate calculation and obtain more accurate statistics. this paper comprises four sections. firstly, complete the rest of the section . secondly in the section presents material and methods. discussions and results are illustrated in the section , while the fourth section introduces conclusions and future works. a patient with symptoms similar to covid- is suspected patient, however; a patient is still exposed to infected eventhough the results of the laboratory tests are reported negative. in this case a patient is considered to be exposed to infection until proven to be recovered or infected after days based on the world health organization (who) report. therefore, either discharged a patient from hospital or consider as infected patient, this is basically depends on the symptums at period between ( - ) days. infected patients could be recovered and discharges. or died due to severe complication of covid- , see figure ( ). ( ) has been utilized to determine case fatality rate (cfr) [ ] , [ ] , [ ] , [ ] . where nd is a number of deaths due to covid- and ncc is a number of closed cases of covid- . the number of the closed cases is the sum of the number of the death number and the number of recovered patients, see figure ( ). this figure reflects a brief description of the covid- virus journey developing across time. there are four stages a patient may go through: (suspected, exposed, infected and dead). the first stage presents a patient who may suffer from symptoms that could be a corona virus symptom or not, or patient has not any symptoms, but he or she in contact with the confirmed person with the virus. in the second stage, patient is still exposed to the infection, but if a patient has severe symptoms with proof, patient could be infected. infected confirmed patient may be recovered or died depends of the level of virus load and immunity of the body. fatality rate is related with number of recovered and dead patients. if we examine the fatality rate for the coronavirus in different countries, for example, usa, spain and italy, some of the greatly affected countries, we can see that these countries, despite their advanced healthcare systems that they have established, have a much higher fatality rate in comparison to some poorer countries, for example iraq, egypt and sudan that do not have very progressive health systems, but regardless of that, have lower deaths. the data were obtained from accurate databases including worldometer [ ] . it was collected form a set of countries across different continents (usa, spain, italy, iraq, iran, uzbekistan, egypt and australia) at the period between th march and th may, . the main reason is to observer the impact and spreading of the covid- at different regions. moreover, the values of the fatality rate of covid- can be vary considerably across different places. the purpose of the comparison is to estimate possible effects of the demographic characteristics of population and ethnic origin on the epidemic outcomes. this data includes population, total daily active cases, total daily of dead infected patients and total daily recovered patient from covid- . case fatality rate (cfr) was evaluated using equation ( ) for a set of countries across different continents in two months. furthermore, a state of art algorithm has been proposed to determine daily cfr. an algorithm is introduced to show the sequence of the instructions to evaluate case fatality rate (cfr). this algorithm consists of a set of variables which are defined below: , ..........n, j= , ........ the fatality rate values depend on the accumulation the number of the dead patients and the total number of closed cases. the most significant factor in this equation is the strength of the health system to provide a standard health care to a large number of covid- patients. people awareness about viral spread and their commitment to health authority advice to prevent that is the major factor in limiting the spread of the disease. for example, through these two months ( th march to th may) there are countries that do not have a developed health system such as iraq which was recorded lower values of fatality rates than developed countries. however, through the time, while adhering to the world health organization (who) instructions in these countries, the virus can gradually fade, despite the difference in its variation strength of the virus. therefore, adherence to safety rules which are mentioned above is the primary driver that fights covid . in addition, we do not forget the availability of adequate health services is essential to reduce the high percentage of the deceased patients. in this work, case fatality rate (cfr) has been evaluated and reported in the figure ( ), which demonstrates evaluation across different countries. ( ) . spain and egypt scored the highest on the fatality rate approximately %, while the lowest score was . % for uzbekistan, iraq was % and australia %. in the preivious reserches [ ] , [ ] , [ ] the highest fatality rate was in italy. however, in the our research the statistical analysis are evaluated across course of two mounths ( th march to th may), the world highest cfr rate is in spain, eygpt and spain have approximatly the same score. on the other hand, australia, in the current and previous reserch still has the lowest score of the death and fatality rate. iraq, uzbekistan and iran come from the same continent, meaning that there is similarity in ethnic origins. therefore, they are grouped togather in the same figure to observe the difference in the fatality rate. in this research iraq and uzbekistan approximately have the close score of the fatality rate, see figure ( ) . at the same reason, european countries are grouped in the figure ( ) . the low incidence of the deaths recorded in the epidemic may be due to insufficient testing and the presence of different copies of the virus [ ] , [ ] , [ ] , [ ] . furthermore, evaluation total active cases of covid at the period ( th march - th may) across different countries are illustrated in the table ( ). during these two months, spain, usa and italy have the highest percentage of infected of covid patients, while australia and iraq have the lowest score. the low percentage in australia and iraq compared with other countries could be due to people adhere to the appropriate prevention rules or the virus was on the early stage. where it is possible to answer of this during the next days after two months. the first factor is the adherence of people to the basic rules of social separation in terms of the distance from one person to another, wearing masks and paws. in this paper we also introduced an algorithm to perform more accurate calculations for fatality rate. this algorithm works to classify a patient to a suspect if he or she suffers from symptoms of the virus, but if the laboratory test appears positive, a patient shout infected and if the appears negative, the patient remains exposed to infection for days until it is proven that he is infected or cured. based on the data which were collected at the period between th march and th may, there are some countries that do not have a developed health system, but have recorded lower casualties compared to developed countries. in the case of the worsening of the symptoms of the virus, through this algorithm or application, the health monitoring body is contacted to take appropriate measures. therefore, the main goal of this algorithm is to reduce the momentum on hospitals and shrink the rate of the infection, when the infected person goes to the hospital or health centre will be a carrier of the virus. people 'awareness of the virus's risk and pursuing proper prevention instructions can limit its spread. this is observed in the results in the previous section. hospital capabilities to incubate and manage cases according to a well-thought out protocol that influences of the fatality rate reduction and virus control as well. in this research, an algorithm proposed that can be programmed to be application in the mobile phone, through which information are collected by circulating it as an application using the mobile phone. the patient information based algorithm estimates the fatality rate of covid in real-time to save time , efforts and get a high quailty of the recordings. early transmission dynamics in wuhan, china, of novel coronavirus-infected pneumonia clinical features of patients infected with novel coronavirus in wuhan, china a novel coronavirus associated with severe acute respiratory syndrome a major outbreak of severe acute respiratory syndrome in hong kong epidemiological and clinical characteristics of cases of novel coronavirus pneumonia in wuhan, china: a descriptive study pathological findings of covid- associated with acute respiratory distress syndrome ct imaging features of novel coronavirus ( -ncov) the epidemiology and pathogenesis of coronavirus disease (covid- ) outbreak real-time tentative assessment of the epidemiological characteristics of novel coronavirus infections in wuhan methods for estimating the case fatality ratio for a novel, emerging infectious disease covid- : a dynamic analysis of fatality risk in italy predicted covid- fatality rates based on age, sex, comorbidities, and health system capacity an interpretable mortality prediction model for covid- patients prediction and analysis of covid- positive cases using deep learning models: a descriptive case study of india modelling containing covid- infection. a conceptual model real-time estimation and prediction of mortality caused by covid- with patient informationbased algorithm cross-country comparison of case fatality rates of covid- /sars-cov- , osong public health res perspect estimating the infection and case fatality ratio for coronavirus disease (covid- ) using age-adjusted data from the outbreak on the diamond princess cruise ship similarity in case fatality rates (cfr) of covid- /sars-cov- in italy and china early epidemiological assessment of the transmission potential and virulence of coronavirus disease (covid- ) in wuhan city, china case fatality rate analysis of italian covid- outbreak covid- and italy: what next? lancet, ( ) positive rt-pcr test results in patients recovered from covid- clinical characteristics of coronavirus disease in china risk factors for severity and mortality in adult covid- inpatients in wuhan assay techniques and test development for covid- diagnosis author would like to thank dr. abathar qahtan aladi (consultant in neurology) for for his insightful comments. key: cord- -aunut gj authors: valentine, randall; valentine, dawn; valentine, jimmie l title: relationship of george floyd protests to increases in covid- cases using event study methodology date: - - journal: j public health (oxf) doi: . /pubmed/fdaa sha: doc_id: cord_uid: aunut gj background: protests ignited by the george floyd incident were examined for any significant impact on covid- infection rates in select us cities. methods: eight us cities were studied in which protestors in the tens of thousands were reported. only cities that reside in states whose stay-at-home orders had been rescinded or expired for a minimum of days were included in the sample to account for impact of growth rates solely due to economies reopening. event study methodology was used with a -day estimation period to examine whether growth in covid- infection rates was significant. results: in the eight cities analyzed, all had positive abnormal growth in infection rate. in six of the eight cities, infection rate growth was positive and significant. conclusions: in this study, it was apparent that violations of centers for disease control and prevention (cdc)-recommended social distancing guidelines caused a significant increase in infection rates. the data suggest that to slow the spread of covid- , cdc guidelines must be followed in protest situations. as the covid- pandemic has spread around the usa, social distancing has been advocated to lower rates of infection in major cities. epidemiology findings have probed both the infection's incubation period and death rate [ ] [ ] [ ] but some elements associated with rates of infection are yet to be explored. recently, rates of infection have created many hotspots around the country. the purpose of this study is to examine the impact of the george floyd protests in relationship to the growth of infection rates for the virus. there has been much discussion about the causality of the recent increase in infection rates for major us cities. with states reopening their economies, there has been a fear that relaxed social distancing requirements will result in an increase in new cases. this study used event study methodology to determine the abnormal growth rate that can directly be attributed to the george floyd protests. the eight cities shown in table were studied for two parameters, estimated period for infection growth rate and -day abnormal infection growth rate. data for each parameter were readily available on the google search engine by entering the name of the city and the parameters studied. cities were chosen due to two factors: (i) must be in a state that has reopened for at least days and (ii) had documented protest in the tens of thousands. an event study methodology takes an estimation period of days. in this study, the days are the days after the stay-at-home order was rescinded or expired. this allows the data to account for an increase in infections due to reopening. the abnormal growth is calculated by subtracting the -day infection rate from the estimation period rate. because the data being used in table were publicly available and had no identifiers, institutional review board approval was not required. the results in table show that all eight cities have positive abnormal returns in the weeks after the first day of protests. the -week mark was determined based of the data from the new orleans mardi gras parades that resulted in new orleans becoming a hotspot weeks after the event. this gives time for the incubation period of covid- to take effect, typically believed to occur within -day postexposure. comparing the actual growth rate of infections to the expected growth rate that was comprised of the -day estimation period that happened after there were no stayat-home order in place, it was found that atlanta, miami, orlando, jacksonville, phoenix and houston have significant abnormal returns, whereas seattle and new orleans have positive but insignificant returns. the data set shows that the growth rate after the reopening of economies still showed positive growth infection rates for covid- cases. the data show that atlanta, houston, jacksonville, miami, orlando and phoenix had positive and significant growth after the protests. it is interesting to note that new orleans and seattle, while having positive infection growth rates, findings were not significant. these were the two cities in the data set that were previously designated as hotspots and could indicate that these cities may have benefited from some degree of herd immunity or social awareness of the serious consequences from this viral infection. there has been much discussion about the impact of social distancing on slowing both infection and death rate. research has shown that high-density populations have greater infection rates. further, communities that have enacted and enforced social distancing measures have shown a decrease in infection rate and impacted than changing landscape of public health death rate. , what this study adds this advocates strongly for continued social distancing, as the protests did not follow social distancing guidelines. also, since the protests were held outdoors, the data suggest that viral spread still is ongoing even in warm outdoor environments and that viral spread may not slow in summer months. the study was limited by not knowing the exact number of people that were protesting and lack of contact tracing for those individuals. also, the study was limited by the number of states that were not under stay-at-home orders for a minimum of days to get a valid estimation period for the event study. incubation period and other epidemiological characteristics of novel coronavirus infections with right truncations: a statistical analysis of publicly available case data severe outcomes among patients with coronavirus disease (covid- ) -united states case-fatality rate and characteristics of patients dying in relation to covid- in italy defining the epidemiology of covid- -studies needed demographic science aids in understanding the spread and fatality rates of covid- learning across the uk: a review of public health systems and policy approaches to early child development since political devolution key: cord- -fraczoxu authors: he, wenqing; yi, grace y.; zhu, yayuan title: estimation of the basic reproduction number, average incubation time, asymptomatic infection rate, and case fatality rate for covid‐ : meta‐analysis and sensitivity analysis date: - - journal: j med virol doi: . /jmv. sha: doc_id: cord_uid: fraczoxu the coronavirus disease‐ (covid‐ ) has been found to be caused by the severe acute respiratory syndrome coronavirus (sars‐cov‐ ). however, comprehensive knowledge of covid‐ remains incomplete and many important features are still unknown. this manuscript conducts a meta‐analysis and a sensitivity study to answer the questions: what is the basic reproduction number? how long is the incubation time of the disease on average? what portion of infections are asymptomatic? and ultimately, what is the case fatality rate? our studies estimate the basic reproduction number to be . with the % ci ( . ‐ . ), the average incubation time to be . days with the % ci ( . ‐ . ) (in day), the asymptomatic infection rate to be % with the % ci ( . %‐ . %), and the case fatality rate to be . % with % ci ( . %‐ . %) where asymptomatic infections are accounted for. since the first case of the coronavirus disease- (covid- ) was found in wuhan, china in december , the disease has rapidly spread in the city of wuhan, then to hubei province, china, and subsequently, across the world. on march , the world health organization (who) declared covid- to be a pandemic. patients is important for disease surveillance. to determine how deadly the covid- is, it is fundamental to evaluate the case fatality rate which is calculated as the ratio of the number of deaths from to the number of infected cases. since the outbreak of the disease, a large body of research on covid- has been done and many articles have been published in scientific journals or shared on platforms such as biorxir and medrxir. moreover, covid- data contain substantial errors in that the number of confirmed cases is considerably under-reported, which is attributed to two primary reasons. insufficient test kits do not allow every potential patient with covid- -like symptoms to be tested, and there has been a good portion of asymptomatic covid- carriers who would never be tested and counted as confirmed cases. it is useful to understand the asymptomatic infection rate, defined as the ratio of the number of asymptomatic infections to the number of all infected cases. to address these issues, we carry out a meta-analysis to synthesize the reported estimates of the basic reproduction number, the average incubation time, and the case fatality rate as well as the asymptomatic rate in a rigorous way by factoring out the variabilities associated with the relevant studies. to accommodate the effects of missing asymptomatic infections on calculating the case fatality rate, we further perform a sensitivity analysis for the estimation of the case fatality rate. our table , were identified by the first author (wh) to be included in the analysis, together with serra and day, which were found on april . the inclusion criteria are the availability of both point estimates and % confidence intervals ( % cis) (or equivalently, standard deviations) for the basic transmission number, the average incubation time, the asymptomatic rate, or the case fatality rate. table presents the summary information of the selected articles together with the descriptions of the data used in those articles. we extract the results for the basic reproduction number from , - , , and the results for the average incubation time from. , , , , the results from , , , [ ] [ ] [ ] are extracted for estimation of the asymptomatic infection rate. the estimates for the case fatality rate together with their % cis are taken from. , , , , [ ] [ ] [ ] in the articles, , , the reported % cis were asymmetric which we suspect were caused by employing a transformation (such as the exponential transformation) to the initial cis for the reparameterized effective size; for example, some authors may apply the logarithm to reparameterize the basic reproduction number or the average incubation time before performing the analysis. using the inverse transformation, we convert the reported asymmetric cis and work out the associated standard deviations which are used in determining the weights for the meta-analysis. as shown in the top panel of figures - , estimates of the basic reproduction number, the mean incubation time, the asymptomatic infection rate, and the case fatality rate are quite different from study to study. to obtain synthetic results, we perform a meta-analysis to aggregate the information from multiple studies with the same estimand (or effect size of interest) yet different features including the differences in the data collection, the sample size, and the conditions. suppose k studies report an estimate and the associate standard deviation for an effect size of interest. for the ith study with i = , …, k, let y i denote the effect size of interest and let σ i represent its associated variance estimate. in our analysis here, y i is taken as the basic reproduction number, the average incubation time, the asymptomatic infection rate, and the case fatality rate, respectively. we calculate a weighted average of the results from those k studies under either the fixed effect model or the random effects model. under the fixed effect model, the meta mean effect size is given by and the associated standard deviation is where w i = /σ i is the weight for the ith study. with the random effects model, the meta mean effect size, denoted y meta,r , and its standard deviation, denoted sd(y meta,r ), are determined by the same expression as equations ( ) and ( ) except the top panel of figure shows the results for the basic production number reported in the seven studies. the i index for those studies is . %, suggesting that the random effect model should be considered in conducting the meta-analysis. this result agrees with the perception that the basic reproduction number is time-dependent and varies from place to place. the bottom panel of figure includes the meta-analysis results. days. this estimated average incubation time is about days shorter than the mean incubation time of days announced by ecdc. we point out that our estimate is obtained by combining the information from those studies before february with study subjects in wuhan city or other places in china. in the top panel of figure , we display the estimates of the asymptomatic infection rate reported by. finally, we are interested in estimating the case fatality rate which measures how deadly covid- is for the infected people. the meta-analysis results derived from seven studies available in the literature, shown in the top panel of figure , are reported at the bottom panel of figure , where we assume the random effect models because the i index is . %. the estimated case fatality rate is . %, slightly smaller than . %, the estimate reported on march by the who. the % ci suggests that the average case fatality rate can be as small as . % and as large as . %. these results are obtained from the data up to march which contain five studies with subjects in china and two studies with worldwide subjects. we comment that the true average case fatality rate is ex- to better understand what the true case fatality rate may be, we further conduct two sensitivity studies. in the first study, we repeat the meta-analysis of the case fatality rate in section . by further including the results calculated from the data of the princess diamond cruise. this analysis is driven by the consideration that the case fatality rate derived from the cohort of the cruise passengers is highly likely to be accurate, because the number of confirmed cases from the cruise is very likely to be close to the true number of infections. the bottom of figure reports the meta-analysis results in our second sensitivity analysis, we revise the results in let p r = d/c r be the reported case fatality rate and let p t = d/c be the true case fatality rate. if we assume that c = c r + c a , then the reported case fatality rate and the true case fatality differ by the factor − r a : estimates of the case fatality rate that have been reported in the current literature are merely directed to p r rather than p t . to sensibly estimate the true case fatality, we use equation ( ) to adjust the reported results of the seven studies listed at the top panel of figure . specifically, we may multiply the factor − r a with an estimate for the reported rate p r as well as its standard deviation for each study and then run a meta-analysis. however, the exact value of the asymptomatic infection rate is unavailable, and we only have its estimates from various studies displayed at the top panel of figure . to assess how the uncertainty of not knowing the true value of r a , we use two ways to set a value for r a to modify the reported fatality rates for the studies listed at the top panel of figure for running a new meta-analysis. first, taking r a as one of seven reported estimates listed at the top panel of figure , we modify the reported results provided by each study listed at the top panel of figure using equation ( ), and report the meta-analysis results at the top panels of figure . in the second analysis, we take r a as the synthesized estimate reported in figure , that is, r a is set as %, and then run the meta-analysis for these adjusted case fatality rates under the random effects model. we report the results at the bottom panel of figure , which shows that the estimate of the case fatality rate is . % with the % ci ranging from . % to . %. we carry out a meta-analysis and sensitivity study for estimating the basic reproduction number, the average incubation time, the asymptomatic infection rate, and the case fatality rate for covid- . examining the published results between january and world health organization ( ) covid- situation reports report : transmissibility of -ncov il % dei donatori di sangue`e positivo covid- : four fifths of cases are asymptomatic, china figures indicate an investigation of transmission control measures during the first days of the covid- epidemic in china science early transmission dynamics in wuhan, china, of novel coronavirus-infected pneumonia novel coronavirus -ncov: early estimation of epidemiological parameters and epidemic predictions time-varying transmission dynamics of novel coronavirus pneumonia in china incubation period of novel coronavirus ( -ncov) infections among travellers from wuhan, china modelling the epidemic trend of the novel coronavirus outbreak in china does sars-cov- has a longer incubation period than sars and mers? likelihood of survival of coronavirus disease estimates of the severity of coronavirus disease : a model-based analysis the incubation period of coronavirus disease (covid ) from publicly reported confirmed cases: estimation and application clinical characteristics of hospitalized patients with sars-cov- infection: a single arm meta-analysis covid- patients' clinical characteristics, discharge rate, and fatality rate of meta-analysis unique epidemiological and clinical features of the emerging novel coronavirus pneumonia (covid- ) implicate special control measures estimation of the asymptomatic ratio of novel coronavirus infections (covid- ) asymptomatic and presymptomatic sars-cov- infections in residents of a long-term care skilled nursing facility a considerable proportion of individuals with asymptomatic sars-cov- infection in tibetan population estimating the asymptomatic proportion of coronavirus disease (covid- ) cases on board the diamond princess cruise ship introduction to meta-analysis quantifying heterogeneity in a metaanalysis r package "forestplot world health organization ( ) who director-general's opening remarks at the media briefing on covid- - estimation of the basic reproduction number, average incubation time, asymptomatic infection rate, and case fatality rate for covid- : meta-analysis and sensitivity analysis the authors declare that there are no conflict of interests. wh identified the articles that were screened by the third author, extracted the results from individual studies, conducted all the data analyses, and prepared the initial draft. gy discussed the analysis methods with wh and wrote the manuscript. yz searched the literature, provided the candidate articles to wh for further examination. http://orcid.org/ - - - key: cord- -a fi ssg authors: pathan, refat khan; biswas, munmun; khandaker, mayeen uddin title: time series prediction of covid- by mutation rate analysis using recurrent neural network-based lstm model date: - - journal: chaos solitons fractals doi: . /j.chaos. . sha: doc_id: cord_uid: a fi ssg sars-cov- , a novel coronavirus mostly known as covid- has created a global pandemic. the world is now immobilized by this infectious rna virus. as of may , already more than . million people have been infected and k people died. this rna virus has the ability to do the mutation in the human body. accurate determination of mutation rates is essential to comprehend the evolution of this virus and to determine the risk of emergent infectious disease. this study explores the mutation rate of the whole genomic sequence gathered from the patient's dataset of different countries. the collected dataset is processed to determine the nucleotide mutation and codon mutation separately. furthermore, based on the size of the dataset, the determined mutation rate is categorized for four different regions: china, australia, the united states, and the rest of the world. it has been found that a huge amount of thymine (t) and adenine (a) are mutated to other nucleotides for all regions, but codons are not frequently mutating like nucleotides. a recurrent neural network-based long short term memory (lstm) model has been applied to predict the future mutation rate of this virus. the lstm model gives root mean square error (rmse) of . in testing and . in training, which is an optimized value. using this train and testing process, the nucleotide mutation rate of (th) patient in future time has been predicted. about . % increment in mutation rate is found for mutating of nucleotides from t to c and g, c to g and g to t. while a decrement of . % is seen for mutating of t to a, and a to c. it is found that this model can be used to predict day basis mutation rates if more patient data is available in updated time. the whole world is suffering by an ongoing pandemic due to coronavirus disease brought about by severe acute respiratory syndrome coronavirus (sars-cov- ) [ ] . it was an outbreak from wuhan, the capital of hubei province in china during december [ ] . the virus was identified on th january and observed that it is spread by human-to-human transmission via droplets or direct contact [ , ] . its infection has been estimated to be a mean incubation period of . days and a basic reproduction number of . - . . since its identification, it has already been spread speedily over the whole globe, therefore who had declared covid- a global pandemic on th march [ ] . the sars-cov- is a pathogenic human coronavirus under the betacoronavirus genus. in the recent decade, the other two pathogenic species sars-cov and mers-cov were outbreaks in and in china and the middle east, respectively [ ] [ ] [ ] [ ] . the complete genomic sequence (wuhan-hu ) of this large rna virus (sars-cov- ) was first discovered in the laboratory of china on th january [ ] and placed in the ncbi genbank. the sars-cov- is a single positive-stranded rna virus having non-segmented in nucleic acid sequence [ ] . although it is an rna virus but for simplicity of understanding the gene sequence has been given as dna type which means nucleobase uracil (u) has been replaced by thymine (t). the genomic sequence of sars-cov- virus shows about % and % similarity with the sar-cov and mars-cov, respectively [ ] . sars-cov- performs mutation during replication of genomic information [ ] . the mutation occurs due to some errors when copying rna to a new cell. mutations are mainly three kinds: base substitution, insertion, and deletion. further, in base substitutions, there are some more divisions: silent, nonsense, missense, and frameshift [ ] . micro-level alteration of mutation rate is also detectable for virus infection in host immune systems and drastically change the virus characteristic and virulence. to understand viral evolution, the mutation rate is one of the crucial parameters [ ] . furthermore, it is one of the most important factors for the assessment of the risk of emergent infectious disease, like due to sars-cov- . therefore, an accurate estimation of this parameter finds a great significance [ , ] . in connection to this and following the current pandemic, many researchers and scientists are working relentlessly to understand the evolution of sars-cov- . asim et. al have performed phylogenetic analysis of sars-cov- virus based on the spike gene of the genomic sequence [ ] . in this study, they described a detailed genomic sequence of the sars-cov- virus. they identified the factor of endemicity of sars-cov- and then focused to find out the next reservoir of the sars-cov- virus. based on the case study, the authors reported that all sequence of this virus is constituted in a single cluster without making any branching on this ongoing pandemic but not validated the findings with detailed statistical analysis. an analysis on gene signature of sars-cov- virus has been performed by ranajit and sudeep [ ] . they estimate the ancestry rate of the european genome from the reference population by applying a statistical tool qpadm. then they applied pearson's correlation coefficient between various ancestry rate of european genome and performed statistical analysis on death/recovery ratio by using graphpad prism v . . , graphpad software. in this study, they developed different linear regression models. finally, they performed genome-wide association analyses (gwas) among european and east asian genomes to examine single-nucleotide polymorphism (snp) which is correlated to the infection of the sars-cov- virus. from the snp association, they observed a huge difference in allele frequencies between european and eastern asian countries. debaleena et al. analyzed the statistical changes of signature from different variant of sars-cov- virus [ ] . they calculated diversity, non-synonymous, synonymous, and substitution rates for each gene of the nucleotide sequence by using dnasp. they also employed time zone software for phylogenetic analysis and mutation detection for each gene. after that, they compared the sequence alignment of a protein of wuhan and india by using multiple sequence alignment. note that in their study, the mutation rate was not calculated based on the patient's genomic sequence. however, the contemporary literature shows adequate studies on the genomic sequence but very few studies on the mutation rate. therefore, the present study is designed to perform the mutation rate prediction for sars-cov- on the basis of the time series. unfortunately, the current data shows that the sars-cov- virus is highly infectious than the other harmful species of pathogenic human coronaviruses [ ] . world populations are now suffering and are in great anxiety by observing the deadliest effect of this virus. but what can be done to stay healthy or avoid getting infected with the virus is still undiscovered. to stop sars-cov- virus, there is a critical need to invent proper vaccine and antibody based therapy against this virus [ ] . scientists and researchers are trying their best to discover suitable drugs or vaccines to neutralize the effect of this virus on the human body, or at least in helping to create an effective resistance against the spreading out of this virus. for inventing proper drugs and vaccines against covid- rna viruses, genomic sequence and mutation analysis are crucially required. in fact, the viral mutation rate also plays a role in the assessment of possible vaccination strategies. in this regard, we performed a detailed study on the mutation rate of this virus using the available dataset in the ncbi genbank. from this dataset, we have analyzed the genomic sequence of patients from different countries for a period of th january to th may . we focus specifically on the mutations that have developed freely on different dates (homoplasies) as these are likely possibilities for progressing adjustment of sars-cov to its novel human host. specifically, we have calculated the base substitution mutation rates. due to the lack of necessary information for insertion and deletion, we have considered those as substitution mutations to ensure that no nucleotide goes out of count. it is expected that the present analysis would help to understand the changing behavior of this virus in the human body and set up strategies to combat the epidemiological and evolutionary levels. an adequate amount of gene dataset is currently available in the ncbi genbank which has the complete genome sequence of sars-cov- . among the many entities, we have filtered the gene sequence, date of collection, and country of the sample. all genes are taken from the human body who are affected by covid- . there are genes from almost countries but china, australia and the united states has a considerable number of patients' data. though some countries like england, italy, france, spain, and brazil has a very high mortality rate but for the lack of data availability in the ncbi genbank till th may, we were unable to calculate the mutation rates for these countries separately. therefore we have considered these countries along with others those have low gene data sequence available in the genbank as the rest of the world category to cover as much region as possible. table shows the information about the gene dataset. in this dataset, there are also some partial genes. so we filtered them and take only with the level of the complete genome. there is a reference gene sequence of length . finally, we have filtered the dataset by taking a maximum gene length of and a minimum of and avoided the copy sequences. with this filtering process, the total number of patients come down to from , patients from china come down to from , the united states come down to from and australia come down to from . following the size of the available dataset, the mutation rate calculations have been set for four categories: china, united states (usa), australia and the rest of the world. furthermore, the dataset is arranged in a suitable way to separately calculate the nucleotide mutation and codon mutation. the first filtered dataset is to find the nucleotide mutation rate. then we have converted the four raw nucleotides (a=adenine, t=thymine, c=cytosine and g=guanine) into codon set. a codon consists of three nucleotides and forms a unit of genetic code in dna or rna. information given in table is used to convert the gene sequence by their index number. for example, if three consecutive nucleotides are 'ttt' then it will be converted to , 'gct' is converted into , and so on. the conversion process has been shown in figure . this process is important to understand the mutation in the codon sequence of covid- . also, it helps to lower the computational complexity. gene mutates for many reasons. when rna tries to copy genetic codes form dna it may cause some error which causes mutation. also, errors in dna replication, recombination, and chemical damage in dna causes mutation. there are basically three types of mutations: base substitutions, deletions, and insertions. from this dataset, we can find out the three kinds of substitution mutation which are silent, missense, and nonsense. a silent mutation is the change of codon by which the resulting amino acid remains unchanged. if the resulting amino acid changes then it is called a missense mutation. on the other hand, when changing codon produces the stop signal for gene translation which causes a nonfunctional protein then it is called a nonsense mutation. these three types of substitution mutation of the observed dataset have been shown in figure , where the missense rate is . %, the nonsense mutation rate is . % and the silent mutation rate is . %. if the mutation type is missense then it can be said that the change of nucleotide has affected the protean generation, which may change the behavior of the virus. also, it is hard to identify the cure's gene sequence. the missense nucleotide mutation rate has been calculated by the given algorithm in figure . after using this algorithm equation has been used to convert the values in percentage. here, mutationrate is the final output array, mutation is the output array sized × containing raw values after applying the algorithm, lg is the length of a dataset which is for the full dataset, for china, for australia and for the usa, gs is the length of reference gene sequence which is in this dataset. in this process, we have calculated the nucleotide mutation rate for the prepared dataset. the mutation rate for china has been shown in figure (a). it shows that a huge percent of thymine (t) are being mutated to other nucleotides but not producing the same amount of t again. also, a huge amount of adenine (a) is mutated to other nucleotides. comparing to t and a, cytosine (c) and guanine (g) were not changed much. after that, the mutation rate has been calculated for australia and the usa, and shown in figures (b) and (c). this is clear that all rates have a common factor of having the high mutation rate of t and a. but there is a significant increase in the mutation rate compared to china. this clearly indicates that this virus is very much active in changing its gene sequence. finally, the nucleotide mutation for the full dataset of countries has been shown in figure (d). it shows that c and g mutation rates are almost equal to the usa because there are more data of usa than any other countries. but some changes in t and a can be seen for the dataset for the rest of the world. these values vary on the availability of the data from different countries. the second processed and converted dataset that were prepared previously has been used here to calculate the codon mutation rate, and shown in figure . changes in nucleotide cause changes in codon set, which later affects the protean directly. we have used the same algorithm shown in figure for detecting the codon mutation rate. a small change has been made in the receiving array where array size was × for nucleotide but here the array size is × for codon mutation. after finding the codon mutations, equation has been used to get the rates in percentage. here, codonmutation is the final output array, mutation is the output array sized × containing raw values after applying the algorithm, lg is the length of dataset which is , gs is the length of the reference gene sequence which is in this converted dataset. the codon mutation rate for the full dataset has been shown in figure . from the obtained value it is clear that codons are not frequently mutating like nucleotides. the diagonal values are because that point codons are not changing comparing with reference gene sequence and heights codon mutation rate is . %. in processed nucleotide mutation dataset, we have gene data from th january to th may discontinuously. these dates are in sorted ascending order which makes it easy to consider this as a time series dataset. in one particular date, this dataset has one or more patients. patients are in this dataset for days. by taking all the patient we can find a time series dataset for patients shown in figure . to obtain a day basis time-series dataset we have averaged the mutation rates for different patients in the same date. so the dataset becomes smaller and dates are in non-sequentially increasing order and the mutation rates for days have shown in figure . the low date availability makes it difficult to train a model in such a small amount of data. long short term memory network which is a type of recurrent neural network (rnn) has been used in deep learning. data has been organized as shown in table where each set has a mutation rate of patients. we have divided / % data as training and testing. therefore, we get data for training and for testing. an lstm model has been created with keras, a deep learning api of python and the structure has shown in figure to train the dataset. first, the input layer got the prepared set of training data with neurons. then it has been through a dense layer of neurons with relu activation layer. after that . dropout has been used. another dense layer of neurons has been used with relu activation. then again . dropout is used. finally, dense of neurons has been used as an output layer with adam optimizer. this model gives root mean square error (rmse) of . in testing and . in training. after the train and testing process, the model seems to be working well. so we use the last patients' mutation rate to predict one future patient's mutation rate and then take that patient and again make patients' mutation rate by old and new patient and predicted. by this procedure, we have predicted patients' mutation rate for future time, as shown in figure . the nucleotide mutation rate of th patient in future time has been shown in figure . a little increment of mutation rate can be seen. if more continuous data can be found from different locations and date then this method can be applied to find the mutation rate for one particular date in the future. the covid- pandemic has almost stopped the world in this twenty-first century. the great spreading power mixing with mutation turns this virus greatly powerful and deadly. lockdown has limited the spreading power of this virus temporarily but the mutation power cannot be contained till now as no reliable vaccine has invented yet. in this research, we explain the nucleotide mutation rate and pattern in the codon mutation set. a rnn-based lstm model has been created to predict the future rate of mutation in person's body if effected with covid- . with this model th patient in future time has been predicted. also, we have explained an lstm-rnn model for time series prediction based on patients' nucleotide mutation rate. by analyzing more patient data in updated time, this model can be used to predict day basis mutation rates. the situation may change if a reliable way of cure would be invented. also in this paper, the mutation rate is limited to base substitution only, insertion and deletion rate can be determined in further research. fig. : nucleotide to codon indexing. coronaviridae study group of the international committee on taxonomy of viruses. the species severe acute respiratory syndrome-related coronavirus: classifying -ncov and naming it sars-cov- laboratory testing of novel coronavirus ( -ncov) in suspected human cases: interim guidance a novel coronavirus outbreak of global health concern who declares covid- a pandemic clinical features of patients infected with novel coronavirus in wuhan genomic characterisation and epidemiology of novel coronavirus: implications for virus origins and receptor binding genome composition and divergence of the novel coronavirus ( -ncov) originating in china recombination, reservoirs, and the modular spike: mechanisms of coronavirus crossspecies transmission origin and evolution of pathogenic coronaviruses inhibition of sars-cov- replication by acidizing and rna lyase-modified carbon nanotubes combined with photodynamic thermal effect coronaviruses: an overview of their replication and pathogenesis emerging sars-cov- mutation hot spots include a novel rna-dependent-rna polymerase variant mutations: types and causes viral mutation rates increased fidelity reduces poliovirus fitness and virulence under selective pressure in mice quasispecies diversity determines pathogenesis through cooperative interactions in a viral population emergence of novel coronavirus and covid- : whether to stay or die out? investigating the likely association between genetic ancestry and covid- manifestation emergence of multiple variants of sars-cov- with signature structural changes cryo-em structure of the -ncov spike in the prefusion conformation models of rna virus evolution and their roles in vaccine design technical supports from the bgc university computer club has been acknowledged this research received no funding the authors declare no competing financial interest key: cord- -pv fb d authors: imtyaz, ayman; abid haleem,; javaid, mohd title: analysing governmental response to the covid- pandemic date: - - journal: journal of oral biology and craniofacial research doi: . /j.jobcr. . . sha: doc_id: cord_uid: pv fb d abstract background and aims covid- , which started as an epidemic from china in november , was first reported to who in december . it had spread to almost all countries globally by march . the pandemic severely affected health and economy globally, prompting countries to take drastic measures to combat the virus. this study aims to analyze different governments' responses to the pandemic to gain insights on how best to fight the coronavirus. methodology various data analysis operations like clustering and bivariate analysis were carried out using python, pandas, scikit-learn, and matplotlib to clean up, consolidate, and visualize data. insights were drawn from the analysis conducted. results we identified that the mortality rate/case fatality rate is directly proportional to the percentage of elderly (people above years of age) for the top thirty countries by cases. countries in western europe showed the highest mortality rates, whereas countries in south asia and the middle east showed the lowest mortality rate (controlling for all other variables). conclusion lockdowns are effective in curbing the spread of the virus. a higher amount of testing resulted in a lesser spreading of the virus and better control. in most regions, countries that were conducting a large number of tests also seemed to have lower mortality rates. in december , doctors in the hubei province of china started reporting cases of a new type of viral disease that they found hard to treat. the disease seemed to have originated in the city of wuhan. within a few weeks, the disease spread like wild fire across many provinces in china, prompting the authorities to effectuate a complete shutdown of economic, commercial, social, and cultural activities, to quell the spread of the virus .within the span of to months, the virus had made landfall in europe and america, spreading rapidly with the help of air travel and unrestricted movement of people across open borders (in europe). by mid-march, the virus had landed in almost all of the un member states and was declared a pandemic. countries most affected by it had enacted some form of a lockdown or the other to stop its spread. efforts were made to enforce social distancing in the early stages to various degrees in different countries to stop the growth rate from exponential. however, thus far, only a handful of countries have had success in curbing the virus. as of st june : - . million cumulative cases have been reported globally, with deaths and recoveries numbering at thousand and . million, respectively. this study aims to establish a basis for the causal relationship between the severity of the pandemic in a country and the government's handling. if such a relationship can be established, it can give governments vital insights that can be used to enact effective policy and legislation against the pandemic. this study will focus on drawing insights from publically available data and statistics on the coronavirus. the data that will be considered for the study are aggregated covid- patient statistics like daily cases, deaths, recoveries, testing data, etc. python has been used for carrying out the analysis. the study's depth will be limited to some exploratory data analysis, data analysis for correlation and cause-and-effect relationships, bivariate analysis, data visualization, and some k-means clustering. data from the worst affected countries (by cases) are considered in this analysis. the data used in the analysis conducted were obtained from publically available, and the government reported statistics on covid- patients in their countries. the primary dataset used is sourced from the john hopkins university center for system science and engineering (csse). the dataset consisted of aggregated data from various sources such as the who, european center for disease prevention and control, the united states cdc, and various other governmental and non-governmental organizations. the raw form data consisted of total cases segregated at city and district levels for every country. the cases were grouped by country in the analysis. link to the data source (github): https://github.com/cssegisanddata/covid- . testing data was collected from ourworldindata.org. link to the data source (ourworldindata.org): https://ourworldindata.org/grapher/number-ofcovid- -tests-per-confirmed-case. the analysis is based on data up to st june . statistical analyses were carried out on the data using well documented and practised methods. the software used is ubiquitous, open-source, and unquestioned in their accuracy and mode of operation. the data's sample size was big enough to consider the data to represent the population, and as such, generalizations could be made for the whole population using the insights obtained from analyzing the data. countries were separated into groups based on the percentage of their elderly population, and the covid- mortality rate (total deaths/total cases). the method is used to divide the countries into groups is the k-means clustering method, based on the elkan algorithm . the k-means method aims to reduce intra cluster variance while maximizing inter-cluster variance. feature scaling was not needed as both the features were on a similar scale from the start, and both features were given equal priority in the clustering. the number of clusters and number of dimensions/features did not warrant giving any aforethought to considerations of computational costs and complexity. the initial centroids were selected at random from the dataset. five clusters are identified as they seemed to stratify the data in the most convenient and explanatory manner, without sacrificing too much in terms of the sum of the squared distance of all the clusters (loss/error function). the analysis was carried out on the jupyter notebooks platform, using the python programming language. • pandas -used for storing data; pandas is a data storage, handling, and manipulation package used with python. • matplotlib -charts and graphs were generated using the pyplot library from matplotlib, a popular data visualization package for python. • scikit-learn -k-means clustering was done with the help of the sklearn. cluster library from scikit-learn, a popular machine learning, and data preprocessing package used with python. link to the code for this analysis: https://github.com/aymanimtyaz/covid- government response to the coronavirus pandemic can be divided into two parts: • efforts in curtailing the spread of the virus (i.e., flattening the curve) • efforts in the handling and treatment of covid- positive patients one metric to gauge the efficacy of government response in handling covid- positive patients is the mortality rate/case fatality rate. the mortality rate is the total number of deaths attributed to the virus divided by the total number of covid- positive cases. analysis of early cases in china led to the observation that the virus poses a more considerable danger to the elderly and people with some underlying comorbidities such as hypertension, diabetes, and heart disease , . this trend continued as the virus spread around the world. it has been established that the coronavirus poses an enormous amount of danger to the elderly. more than per cent of the deaths attributed to the virus are in elderly patients, considering a worldwide average. as we can see from the chart below, there seems to be a linear relationship between the mortality rate and the percentage of older people (people above the age of ) in a country. the variance in the chart may/can be attributed to other factors, such as handling of covid- positive patients, methods of data collection and reporting, other population demographics like genetic makeup, trends in disease, disabilities, and malnutrition, competency, scale, and accessibility of the country's medical apparatus, economic status of the country (gdp, ppp, poverty levels, etc.). the countries on the chart in figure have been clustered into five groups using the k-means clustering algorithm. we shall examine each group below. the cluster towards the upper right-hand corner of the chart is the one with the countries having the highest percentage mortality and the highest percentage of older people compared to the other clusters apart from the cluster containing germany and portugal. the prime reason for the high mortality is evident from the chart itself, a more significant number (by percentage) of older people in these countries. all these countries belong to western europe, except sweden. however, sweden's mortality rate has been increased owing to other reasons which we shall discuss further. more than half of belgium's covid- deaths are in care homes for older people. belgium comes third in place in europe for the number of people in old-age homes per . it, coupled with belgium having among the highest percentages of people above , may have increased the rate. one point to note is how belgium counts deaths due to the virus. a significant percentage of the counted deaths have not been tested positive for the virus. almost all of the people, in this case, resided in old age homes. the justification given for counting them in the deaths is that if there is even one confirmed case in an old age home, and if a significant amount of people die in a short period close to the diagnosis of the confirmed case, showing similar symptoms. there is a high probability that those people also died due to the virus. this method may have resulted in a small number of false positives, which may have wrongly increased the rate. unlike other countries in the top cases list, sweden did not implement a lockdown. it merely encouraged its citizens to stay indoors. public places like restaurants, bars, businesses, schools, and universities were allowed to remain open. it may have contributed to the increased mortality rate; however, how much the decision against a lockdown influenced the mortality rate remains to be seen. apart from their decision to not implement a lockdown, a large proportion of sweden's elderly also resides in nursing homes, just like belgium. unlike belgium, however. sweden only attributes deaths to the virus after a positive test has been confirmed. this cluster consists of the united states, canada, switzerland, germany, and portugal. in this group, germany and portugal seem to be doing very well concerning the percentage of elderly in their population. up until late april, germany had a case fatality rate of %- %. this has been attributed to the amount of testing the germans had been carrying out, unlike other european countries having similar age demographics. germany was testing at a much higher rate. they were even testing young people with mild symptoms. the number of cases is directly proportional to the testing level, and as these two stats increased, the mortality rate started to drop. germans also have a large amount of trust in their government, which, throughout the pandemic, has maintained a very high level of transparency and communication with the public, giving updates to them on the daily. as such, social distancing norms given by the government were rarely broken by the german public. portugal's low mortality rate is accredited because they started responding to the pandemic well before it spiralled out of control. portugal declared a state of medical emergency when they had a few or so cases, compared to spain, who declared an emergency when the growth had already gone exponential, and they had around cases. portugal is also unique because, unlike other european countries, it only has one land neighbour through which inter-country road-based transmission of the disease was possible. it had also managed to isolate more than % of the cases to of its cities, lisbon and porto. people with mild symptoms were instructed to stay at home, while series cases were admitted in hospitals. the united states currently leads the charts in cases in deaths by a wide margin. lockdowns were imposed on varying levels across the country, and different states have handled the pandemic differently. the situation was also highly politicized, with different media outlets giving a different spin to how the situation is. much misinformation is being spread, resulting in sections of the public flouting social distancing norms. this group consists of the latin american countries of peru, brazil, ecuador, and mexico. along with iran, china, and turkey. the clustering algorithm seems to have clustered these countries together based on the elderly's percentage, as the intra-cluster variance in mortality rate is very high. mexico warrants a little discussion here. it has an unusually high case fatality rate of %. one of the prime reasons for this is that mexico has one of the lowest testing rates globally, at around . tests per confirmed case. this means that they are not testing enough-the who recommends a testing rate of - tests per confirmed case for most countries. since the testing rate is so low, that the mortality rate gets inflated, low testing rates may result in improper handling of the spread of the virus , . more the number of people tested, more the number of positive cases isolated, and a lesser amount of untested, covid- positive people who can go around spreading the virus. the cluster towards the lower-left corner consists of those countries, which show a low mortality rate and have the lowest percentage of the elderly among all the countries. the cluster can be further divided into three groups. the first group consists of saudi arabia, qatar, and the united arab emirates, which are the gcc's three foremost countries. these countries have large immigrant worker populations that mostly consist of young males who reside in large dormitories, much like singapore. these countries also have many monetary resources that they can utilize in treating covid- positive patients with a high standard of care. as such, they all boast mortality rates of less than %. the second group consists of the countries in the indian subcontinent: -india, pakistan, and bangladesh. they have mortality rates between % and %, in the early stages of the epidemic. these countries had implemented among the strictest lockdowns in the world. india and bangladesh have only just lifted their lockdowns. the lockdowns have had a definite impact on curtailing the cases' spread, as both india and bangladesh have seen record increases in the number of new cases daily after the lockdowns were lifted. the only remaining country in this group in south africa has also implemented a lockdown a few weeks after detecting its first case. much like other countries in africa, south africa also has a large proportion of young people who may help offset the mortality rate. however, health conditions like obesity, hypertension, etc. are prevalent there. according to some statistics, over half of all south africans are considered to be overweight. the result of this comorbidity seems to be reflected in the age distribution of deaths, two-thirds of deaths due to the virus are in people below . this group consists of singapore, chile, russia, and belarus. about the percentage of elderly in these countries, the deaths seem to be less. if we follow the graph's linear trend, these countries should have a mortality rate of % to %. singapore has among the lowest covid- mortality rates in the first infected countries by cases. this can be attributed to the fact that over % of the confirmed cases are those of young migrant workers living in large, tightly packed dormitories where the virus's probability is high. an overwhelming majority of these workers show no to very mild symptoms, if at all. singapore is also one of the world's wealthiest countries, and as such, it can allocate a large number of resources towards combating the virus. russia has the third-highest number of cases globally; however, it reports one of the lowest mortality rates. the russian government attributes the low mortality rate to the late emergence of the virus compared to europe and north america, which gave it time to set up the infrastructure to handle the virus and gave it some precedent in what to do and what not to do. russia also has a high per capita testing rate. russia, belarus, and chile are accused of manipulating statistics related to the pandemic. this study identifies significant findings as: • european countries were found to have the highest case fatality rates, may be because of age demography and comorbidity • variance in the chart can be explained as being a result of government response to the pandemic • countries like germany, portugal, and singapore seem to have implemented reasonable measures against the virus, as their mortality rates are lower than in other countries with similar age demographics • countries like mexico and brazil need to increase their testing rate in terms of both per capita testing and several tests per positive case this analysis makes the following major inferences: • a relationship exists between the case fatality rate and the percentage of elderly in a country • a high testing rate (tests per capita) and a test per confirmed case rate of - help reduce the virus's spread and reduce/give a more accurate value of the case fatality rate • standardized testing and data collection protocols are needed across the globe for ensuring that the data being used in these kinds of analyses is worthwhile this research infers specific issues which are given below. we can say that government response to the pandemic can affect the pandemic's severity in a country. steps like enforcement of lockdowns and social distancing norms effectively curt the virus's spread, as we have seen in countries like india. smaller countries with less distributed population centres and good travel infrastructure are mediums through which the virus can rapidly spread (see: -europe). social distancing norms and lockdowns would have to be enforced with a higher stringency level to bring about any meaningful containment of the virus. testing is of paramount importance when it comes to combating the virus. it is through testing that statistics related to the pandemic are obtained. keeping this in mind, governments should allocate a more considerable amount of resources towards testing. the effect of other factors that may be related to the pandemic should be explored. this study has not covered any kind of forecasting. the topic of the study (covid- pandemic) is currently an evolving situation. the insights drawn from this study may not apply down the road. the data being considered is publically available; the government reported patient data from th january to st june . a problem like covid- cannot be modelled accurately in a bivariate system. thus, such a complex problem is almost certainly dependent on a host of other factors, apart from the elderly's percentage in a country. every country follows its protocols for reporting data and statistics related to the covid- pandemic. furthermore, the protocols may be different for subdivisions in the country. different states, districts, jurisdictions, etc. may have different methods of counting. this problem gets exacerbated by developing countries where there are not any protocols for data counting and reporting at all. this lack of consistency in reporting protocols may result in inaccurate data, which imparts inaccuracy to the analyses that use that data. russia, belarus, chile, china, etc. have been accused of manipulating their testing and patient data. other factors that can affect the mortality rate, apart from %age elderly are: • genetic makeup. • trends in disease, disabilities, and malnutrition • competency, scale, and accessibility of the country's medical apparatus • vaccination history • the economic status of the country (gdp, ppp, poverty levels, etc.) these factors should be taken into consideration in future analyses. a more in-depth study of the effects of lockdowns has to be done. lockdowns are harder to implement for poorer countries as their economy starts to shake. studies must be done to determine if these cycles of lockdowns are a viable option in fighting the covid- pandemic. moreover, if so, how to time and size different cycles of lockdown. none coronavirus disease in elderly patients: characteristics and prognostic factors based on -week follow-up using the triangle inequality to accelerate k-means covid- : how to fight disease outbreaks with data covid- -virtual press conference contentious issues and evolving concepts in the clinical presentation and management of patients with covid- infection with reference to use of therapeutic and other drugs used in co-morbid diseases clinical considerations for patients with diabetes in times of covid- epidemic key: cord- -loi vs y authors: mueller, markus; derlet, peter; mudry, christopher; aeppli, gabriel title: using random testing in a feedback-control loop to manage a safe exit from the covid- lockdown date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: loi vs y we argue that frequent sampling of the fraction of infected people (either by random testing or by analysis of sewage water), is central to managing the covid- pandemic because it both measures in real time the key variable controlled by restrictive measures, and anticipates the load on the healthcare system due to progression of the disease. knowledge of random testing outcomes will (i) significantly improve the predictability of the pandemic, (ii) allow informed and optimized decisions on how to modify restrictive measures, with much shorter delay times than the present ones, and (iii) enable the real-time assessment of the efficiency of new means to reduce transmission rates. here we suggest, irrespective of the size of a suitably homogeneous population, a conservative estimate of for the number of randomly tested people per day which will suffice to obtain reliable data about the current fraction of infections and its evolution in time, thus enabling close to real-time assessment of the quantitative effect of restrictive measures. still higher testing capacity permits detection of geographical differences in spreading rates. furthermore and most importantly, with daily sampling in place, a reboot could be attempted while the fraction of infected people is still an order of magnitude higher than the level required for a relaxation of restrictions with testing focused on symptomatic individuals. this is demonstrated by considering a feedback and control model of mitigation where the feed-back is derived from noisy sampling data. the covid- pandemic has led to a worldwide shutdown of a major part of our economic and social activities. this political measure was strongly suggested by epidemiologic studies assessing the cost in human lives depending on different possible strategies (doing nothing, mitigation, suppression). [ ] [ ] [ ] mitigation can be achieved by different strategies, such as physical distancing, contact tracing, restricting public gatherings, and the closing of schools, but also the testing for infections. the quantitative impact of very frequent testing of the entire population for infectiousness has been studied in a recent unpublished work by jenny et al. in ref. [ ] . we will estimate in sec. iii that to fully suppress the covid- pandemic by widespread testing for infections, one needs a capacity to test millions of people per day in switzerland. this should be compared to the present number of ' tests per day across switzerland. however, we show that tracking and control of this pandemic is possible by testing a much smaller number of randomly selected people per day. in addition, we will argue that even with currently available testing rates, extremely valuable information on the rates of transmission depending on geographic regions of switzerland can be obtained. figure summarizes the key concept of the paper, namely a feedback and control model for the pandemic. the key output from random testing is the growth rate of the number of infected people, which itself is regulated by measures such as those enforcing physical distances between persons (physical distancing), and whose tolerable values are fixed by the capacity of the healthcare system. a feedback and control approach, [ ] familiar from everyday implementations such as for thermostats regulating heaters and air conditioners, should allow policy makers to damp out oscillations in disease incidence which could lead to peaks in stress on the healthcare system as well as the wider economy. a further important benefit of this feedback and control scheme is that it allows a much faster and safer reboot of the economy than with the current feedback through confirmed infection numbers, for the latter is heavily delayed and reflects the state of the pandemic only incompletely. the resulting difference in the ability to control the disease is illustrated in fig. . without feedback and control informed by a key parameter, analogous to the temperature provided by the thermometer in the thermostat example, measurable in (near) real time, there is a huge delay between policy changes and the observable changes in terms of positively tested people. to release restrictions safely, the fraction of infected people must decrease to a level i * * such that a subsequent undetected growth during - days will not move it above the critical fraction i c manageable by the healthcare system. the current situation where we are mainly looking at lagging indicators, namely infection rates among symptomatic individuals or even deaths, is comparable to driving a car from the back seat and with knowledge only of the damage caused by previous collisions. to minimize harm to the occupants of the vehicle, driving very slowly is essential, and oscillations from a straight course are likely to be large. daily random testing reduces the delay between changes in policy and the observation of their effects very significantly. moreover, it directly measures the key quantity of interest, namely the fraction of infected people and its growth rate, information that is very valuable to gauge further interventions. such information is much harder to infer from data about positively tested patients only, by fitting it to specific epidemiological models with their inherent uncertainties. the shortened time delay due to feedback and control allows a reboot to be attempted at much higher levels of infections, i * > i * * , which implies a much shorter time in lockdown. the paper is organized as follows. we summarize and explain the key findings of the paper in simple terms in sec. ii. in sec. iii, we discuss the use of massive testing as a direct means to contain the pandemics, showing that it requires a -fold increase of the current testing frequency. in sec. iv, we define the main challenge to be addressed: to measure the quantitative effect of restrictive measures on the transmission rate. section v introduces the idea of randomized testing. section vi constitutes the central part of this paper. it is shown how data from sparse sampling tests can be used to infer essentially instantaneous growth rates, and their regional dependence. we define a model of testing feed-back driven intervention strategy and analyze it theoretically. this model is also analyzed numerically in sec. vii. section viii generalizes the modelling to a regionally refined analysis of the epidemic growth pattern which becomes the preferred choice if higher testing rates become available. we conclude with sec. ix by summarizing our results and their implication for a safe reboot after the current lockdown. in the appendix we address the use of contact tracing and argue that it can complement, but not substitute for random testing. the key quantity measured by random testing is the growth rate k of infection numbers. if k exceeds a tolerable upper threshold κ + , restrictions are imposed. for k below a lower threshold κ − , and if infection numbers are below critical, restrictions are released. in the absence of a substantial influx of infected people from outside the country, and provided infection numbers are below a critical value, the optimal target of the growth rate is k = , corresponding to a marginally stable state, where infections neither grow nor decrease exponentially with time. if higher testing rates are available, the measured observables and control strategies can be geographically refined. we argue that the moderate number of ' random tests per day yields valuable information on the dynamics of the disease. assuming that at a given time a fraction of about i ≈ . % of the population is infected, the order of infected people will be detected every day. can such a small number of detected infections be useful at all, given that these numbers fluctuate significantly from day to day? the answer is yes. we show that after a few days the acquired signal becomes stronger than the noise level. it is then possible to establish whether the infection number is growing or decreasing and, moreover, to obtain a quantitative estimate of the instantaneous growth rate k(t). one of our central results is eq. ( c) for the time where the signal becomes clear, which we rewrite in the simplified form where k is the current growth rate of infections to be detected, and r is the number of tests per day. the numerical constant c depends on the required signal to noise ratio. a typical value when detecting large values of k is c ≈ − . this result shows that the higher the number of tests r per day, the shorter the time to detect a growth or a decrease of the infected population. the smaller the dynamics of the pandemic with and without a feedback and control scheme in place, as measured by the fraction i of infected people (logarithmic scale). after the limit of the health system, i c , has been reached, a lockdown brings i down again. the exponential rate of decrease is expected to be very slow, unless extreme measures are imposed. the release of measures upon a reboot is likely to re-induce exponential growth, but with a rate difficult to predict. three possible outcomes are shown in blue curves in the scenario without testing feedback, where the effect of the new measures becomes visible only after a delay of - days. in the worst case, i grows by a multiplicative factor of order before the growth is detected. a reboot can thus be risked only once i ≤ i * * ≡ i c / , implying a very long time in lockdown after the initial peak. due to the long delay until policy changes show observable effects, the fluctuations of i will be large. random testing (the red curve) has a major advantage. it measures i instantaneously and detects its growth rate within few days, whereby the higher the testing rate the faster the detection. policy adjustments can thus be made much faster, with smaller oscillations of i. a safe reboot is then possible much earlier, at the level of i ≤ i * ≈ i c / . current growth rate k , the longer the time to detect it above the noise inherent to the finite sampling. how long would it take to detect that a release of restrictive measures has resulted in a nearly unmitigated growth rate of the order of k = . (which corresponds to doubling every days)? even with a moderate number of r = per day, we find that within only ∆t ≈ − days such a strong growth will emerge above the noise level, such that countermeasures can be taken (see fig. ). during this short time, the damage remains limited. the infection numbers will have risen by a multiplicative factor between and . this degree of control must be compared to a situation where no information on the current growth rate is available, and where the first effects of a new policy are seen in the increased number of symptomatic, sick people only - days later. over this time span, with a growth rate of k = . , the infection numbers will have grown by a factor of - before one realizes eventually that an intervention must be made. random testing decreases both the time scale until informed policy adjustments can be taken and the temporal fluctuations of the infection numbers. as in any feedback and control loop, the more frequent the testing is, the shorter are the delay times, and thus the smaller are the fluctuations. the various benefits of increasing the testing frequency are shown in fig. , which are obtained by simulating a specific mitigation strategy, where we built in the uncertainty about the efficacy of political interventions. the shorter delay times and the reduced fluctuations result in decreased strain on the health system, lower economic costs, and a lower number of required interventions. in addition to these benefits, a higher testing rate r also opens the opportunity to analyze geographic differences and refine the mitigation strategy accordingly, as we discuss in sec. viii. if the massive frequency of . million tests per day becomes available in switzerland, it will be possible to test any swiss resident every to days. if the infected people that have been detected are kept in strict quarantine (such that they will not infect anybody anymore with high probability), such massive testing could be sufficient to prevent an exponential growth in the number of cumulated infections without the need of draconian physical distancing measures. we now explain qualitatively our approach to reach this conclusion. a refined analysis has been given in ref. [ ] . the required testing rate can be estimated as follows. let ∆t denote the average time until an infected person infects somebody else. the reproduction number r, i.e., the number of new infections transmitted on average by an infected person, falls below (and thus below the threshold for exponential growth) if non-diagnosed people are tested at time intervals of no more than ∆t . thus, the required number of tests over the time ∆t , the full testing rate τ − full , is where is the number of inhabitants of switzerland. without social restrictions, it is estimated that [ ] ∆t ≈ days, such that i.e., about . million tests per day would be required to control the pandemics by testing only. if additional restrictions such as physical distancing etc., are imposed, ∆t increases by a modest factor and one can get by with indirectly proportionally fewer tests per day. nevertheless, on the order of million tests per day is a minimal requirement for massive testing to contain the pandemics without further measures. however, even while the swiss capabilities are still far from reaching million tests per day, testing for infections offers two important benefits in addition to identifying people that need to be quarantined. first, properly randomized testing allows to monitor and study the efficiency of measures that keep the reproduction number r below . this ensures that the growth rate k of case numbers and new infections is negative, k < . second, frequent testing, even if applied to randomly selected people, helps suppress the reproduction number r and thus allows policy to be less restrictive in terms of other measures, such as physical distancing. to quantify the latter benefit, observe that the effect of massive testing on the growth rate k is proportional to the testing rate. [ ] let us assume that without testing or social measures one has a growth rate k . then, if the testing rate τ − full is sufficient to completely suppress the exponential growth in the absence of other measures, a smaller testing rate τ − decreases the growth rate k down to (τ − /τ − full ) × k . the remaining reduction of k to zero must then be achieved by a combination of restrictive social measures and contact tracing. it is possible to refine the argument above to take account of the possibility of a spectrum of tests with particular cost/performance trade offs, i.e., a cheaper test with more false positives and negatives could be used for random testing, whereas those displaying symptoms would be subjected to a "gold standard" (pcr) assay of viral genetic material. a central challenge for establishing reliable predictions for the time evolution of pandemics is the quantification of the effect of social restrictions on the transmission rate. [ ] policymakers and epidemiologists urgently need to know by how much specific restrictive measures reduce the growth rate k. without that knowledge, it is essentially impossible to take an informed decision on how to optimally combine such measures to achieve a (marginally) stable situation, defined by the condition of a vanishing growth rate indeed, marginal stability is optimal for two reasons. first, it is sustainable in the sense that the burden on the health system does not grow with time. second, it is the least economically and socially restrictive state compatible with the stability requirement. in secs. v and vi, we show how marginal stability can be achieved, while simultaneously measuring the effects of a particular set of restrictions. we claim that statistically randomized testing can be used in a smart way, so as to keep the dynamics of the pandemics under control as per the feedback loop of fig. . we emphasize that this is possible without the current time delays of up to days. the latter arises since we only observe confirmed infections stemming from a highly biased test group that eventually shows symptoms long after the initial infection has occurred. the idea of smart testing is the following. one regularly tests randomized people for infectiousness we stress that randomized testing is essential to obtain information on the current number of infections and its evolution with time. it serves an additional and entirely different purpose from testing people with symptoms, medical staff, or people close to somebody who has been infected, all of whom constitute highly biased groups of people. the first goal of random testing is to obtain a firm test/confirmation of whether the current restrictive measures are sufficient to mitigate or suppress the exponential growth of the covid- pandemic, and whether the effectiveness differs from region to region. in case the measures should still be insufficient, one can measure the current growth rates and monitor the effect of additional restrictive measures. it is important that the set of randomly selected people must change constantly, so that it should happen extremely rarely that a given person is tested twice. here, we solely focus on a person being infectious, but not on whether the person has developed antibodies. the latter test indicates that the person has been infected any time in the past. testing for antibodies and (potential) immunity has its own virtues, but aims at different goals from the random testing for infections that we advocate here. by following the fraction of infections as a function of time, we can determine nearly instantaneously the growth rate of infections, k(t), and thus assess and quantify the effectiveness of socio-economic restrictions through the observed changes in k following a change in policy. this monitoring can even be carried out in a regionally resolved way, such that subsequently, restrictive or relaxing measures can be adapted to different regions (urban/rural etc.). a suppression of the covid- pandemic is achieved if, for a sufficiently long time, the number of infections decays exponentially with time. mitigation aims to reduce the exponential rate of growth in the number of infections. stability is achieved when that number tends to a constant. once stability is reached, one may start relaxing the restrictions step by step and monitor the effect on the growth rate k as a function of geographic regions. . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint we first analyze random testing for the case where we treat the country as a homogeneous entity with a population n . this will allow us to understand how testing frequency affects key characteristics of policy strategies. we consider the following model. let u be the actual undetected number of infected people. (we assume that detected people do not spread the disease.) the spreading of infections is assumed to be governed by the inhomogeneous, linear growth equation where k(t) is the instantaneous growth rate and Φ(t) accounts for infections arising from people crossing the national border. we will later set that influx to zero. an equation of the form ( ) is usually part of a more refined epidemiological model [ ] [ ] [ ] that accounts explicitly for the recovery or death of infected persons. for our purpose, the effect of these has been lumped into an overall time-dependence of the rate k(t). for example, it evolves as the number of immune people grows, restrictive measures change, mobility is affected, new tracking systems are implemented, hospitals reach their capacity, testing is increased, etc. nevertheless, over a short period of time where such conditions remain constant, and the fraction of immune people does not change significantly, we can assume the effective growth rate k(t) to be piecewise constant in time. we will exploit this below. for t < , we assume stability with such a stable state needs to be reached before a reboot of the economy can be considered. at t = restrictive measures are first relaxed, resulting in an increase of the growth rate k from k to k , which we assume positive, hence, compensating counter measures are required at later times in order to avoid another exponential growth of the pandemic. we now want to monitor the performance of policy strategies that relax or re-impose restrictions, step by replacing the function k(t), assumed to be differentiable, by a piecewise constant function is a good approximation provided wherek(t) is the time derivative of k(t) and ∆t(k) is given by eq. ( a) with the replacement k → k(t). step. the goal for an optimal policy strategy is to reach a marginally stable state ( ) (i.e., with k = ) as smoothly, safely, and rapidly as possible. in other words, marginal stability is to be reached with the least possible damage to health, economy, and society. this expected outcome is to be optimized while controlling the risk of rare fluctuations. to model the performance of policy strategies we neglect the contributions to the time evolution of k(t) due to the increasing immunity or the evolution in the age distribution of infected people. we also neglect periodic temporal fluctuations of k(t) (e.g., due to alternation between workdays and weekends), which can be addressed in further refinements. instead, we assume that k(t) changes only in response to policy measures which are taken at specific times when certain criteria are met, as defined by a policy strategy. an intervention is made when the sampled testing data indicates that with high likelihood, k(t) exceeds some upper threshold likewise, a different intervention is made should k(t) be detected to fall below some negative threshold note that if there is substantial infection influx Φ(t) across the national borders, one may want to choose the threshold κ + to be negative, to avoid a too large response to the influx. from now on we neglect the influx of infections, and consider a homogeneous growth equation. to reach decisions on policy measures, data is acquired by daily testing of of random sets of people for infections. we assume that the tests are carried out at a limited rate r (a finite number of tests divided by a nonvanishing unit of time). let i(t, ∆t) be the fraction of positive infections detected among the r ∆t tests carried out in the time interval [t, t + ∆t]. by the law of large numbers, it is a gaussian random variable with mean and standard deviation the current value of k(t) is estimated as k fit (t) by fitting these test data to an exponential, where only data since the last policy change should be used. the fitting also yields the statistical uncertainty (standard deviation), which we call δk(t). it will take at least - days to make a fit that is reasonably trustworthy. if the instability threshold is surpassed by a certain level, i.e., if . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint a new restrictive intervention is taken. if instead a new relaxing intervention is taken. here, the parameter α is a key parameter defining the policy strategy. it determines the confidence level that policymakers require, before deciding to declare that a stability threshold has indeed been crossed. this strategy will result in a series of intervention times starting with the initial step to reboot at t = . in the time window [t ι , t ι+ ], the growth rate k(t) is constant and takes the value where the policy choice ∆k (ι) > corresponding to a restrictive measure is made to bring back k(t) below the upper threshold κ + , while the policy choice ∆k (ι) < is made to bring back k(t) above the lower threshold κ − . the difficulty for policymakers is due to the fact that so far the quantitative effect of an intervention is not known. we model this uncertainty by assuming ∆k (ι) to be random to a certain degree. if at time t, k fit (t) crosses the upper threshold κ + with confidence level p, we set t ι = t and a restrictive measure is taken, i.e., ∆k (ι) is chosen positive. we take the associated decrement ∆k (ι) to be uniformly distributed on the interval , ∆k this describes that while the policymakers aim to reset the growth factor k to κ + , the result of the measure taken may range from having no effect at all (when ∆k (ι) = ) to overshooting by a factor of (when ∆k (ι) = ∆k opt,+ being optimum. if instead k fit (t) crosses the lower threshold κ − with confidence level p at time t, we set t ι = t and a releasing measure is taken, i.e., ∆k (ι) is chosen negative. again, with the optimum choice ∆k the process described above is stochastic for two reasons. first, the sampling comes with the usual uncertainties in the law of large numbers. second, the effect of policy measures is not known beforehand (even though it may be learnt in the course of time, which we do not include here). it should be clear that the faster the testing the more rapidly one can respond to a super-critical situation. a significant simplification of the model occurs when the two thresholds are chosen to vanish, in which case with |∆k (ι) | uniformly distributed on the interval in this case the system will usually tend to a critical steady state with k(t → ∞) → , as we will show explicitly below. in this case the policy strategy can simply be rephrased as follows. as soon as one has sufficient confidence that k has a definite sign, one intervenes, trying to bring k back to zero. the only parameter defining the strategy is α. let us now detail the fitting procedure and analyze the typical time scales involved between subsequent policy interventions when choosing the thresholds ( ). after a policy change at time t ι , data is acquired over a time window ∆t. we then proceed with the following steps to estimate the time t ι+ at which the next policy change must be implemented. step : measurement we split the time window of length ∆t after the policy change into the time interval and the time interval testing delivers the number of infected people for the time interval ( b) and . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint for the time interval ( c), where we recall that r denotes the number of people tested per unit time. given those two measurements over the time window ∆t/ , we obtain the estimate with the standard deviation as follows from the statistical uncertainty n ι,γ (∆t) of the sampled numbers n ι,γ (∆t) and standard error propagation. step : condition for new policy intervention a new policy intervention is taken once the magnitude |k fit ι (∆t)| with k fit ι (∆t) given by eq. ( f) exceeds α δk(∆t) with δk(∆t) given by eq. ( g). here, α controls the accuracy to which the actual k has been estimated at the time of the next intervention. the condition for a new policy intervention thus becomes . ( b) step : comparison with modeling we call i(t) the actual fraction of infections (in the entire population) as a function of time, which we assume to follow a simple exponential evolution between two successive policy interventions, i.e., the normalized solution to the growth equation ( ) on the interval t ι < t < t ι+ . the expected number of newly detected infected people in the time interval ( b) is similarly, the predicted number of infected people in the time interval ( c) is step : estimated time for a new policy intervention we now approximate n ι, and n ι, by replacing them with their expectation value eqs. ( a) and ( b), respectively, and anticipating the limit we further anticipate that for safe strategies the fraction of infected people i(t) does not vary strongly over time. more precisely, it hovers around the value i * defined in fig. . we thus insert into eq. ( b) and solve for ∆t. the solution is the time until the next intervention from which we deduce the relative increase of the fraction of infected people over the time window. this relative increase is close to if the argument of the exponential on the right-hand side is small. we will show below that the characteristics and of the first time interval [t , t ] set the relevant scales for the entire process. from eqs. ( c) and ( d), we infer the following important result. the higher the testing frequency r, the smaller the typical variations in the fraction of infected people, and thus in the case numbers. the band width of fluctuations decreases as r − / with the testing rate. note that, as one should expect, it is always the average rate to detect an infected person, r i * , which enters into the expressions ( c) and ( d). the higher the fraction i * , the more reliable is the sampling, the shorter is the time to converge toward the marginal state ( ), and the smaller are the fluctuations of the fraction of infected people. . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint if the fraction i * is too low the statistical fluctuations become too large and little statistically meaningful information can be obtained. on the other hand, if the fraction of infections drops to much lower values, then policy can be considered to have been successful and can be maintained until further tests show otherwise. we seek an upper bound for a manageable ı * . we assume that a fraction p ch icu of infected people in switzerland needs to be in intensive care. more precisely, p ch icu is the expected time (in switzerland) for an infected person to spend in an intensive care unit (icu) divided by the expected time to be sick. here, we will use the value p ch icu = . . let ρ icu be the number of icu beds per inhabitant that shall be allocated to covid- patients. the swiss national average is about [ ] ρ ch icu ≈ for the pandemics not to overwhelm the health system, one thus needs to maintain the infected fraction safely below together with similar constraints related to the capacity for hospitalizations, medical care personnel and equipment for specialized treatments. we take the constraint from intensive care units to obtain an order of magnitude for the upper limit admissible for the infected fraction of people, i. the objective is to mitigate the pandemic so that values of the order of i c or below are achieved. before that level is reached restrictions cannot be relaxed. it may prove difficult to push the fraction of infected people significantly below i c , since the recent experience in most european countries shows that it is very hard to ensure that growth rates k fall well below . the main aim would then be to reach at least stabilization of the number of infected people (k = ). for the following we thus assume that the fraction of infections i will stagnate around a value i * of the order of i c . we will discuss below what ratio i * /i c can be considered safe. we seek the testing rate that is needed to obtain a strategy with satisfactory outcome. we assume that after the reboot at t = , the initial growth rate may turn out to be fairly high, say of the order of the unmitigated growth rate. in many european countries a doubling of cases was observed every three days before restrictive measures were introduced. this corresponds to a growth rate of we assume an initial growth rate of just after the reboot. we choose the reasonably stable confidence parameter in sec. vii we will find that this choice strikes a good balance between several performance criteria. we further assume that the rate of infections initially stagnates at a level of the level i * should, however, be measured by random testing before a reboot is attempted. we should then ensure that the first relative increase of does not exceed a factor of . from eq. ( b), we thus obtain the requirement for the testing rate r. this yields an estimate of the order of magnitude required. in the next section we simulate a full mitigation strategy and confirm that with additional capacity for just about ' random infection tests per day a nation-wide, safe reboot can be envisioned for switzerland. we close with two observations. first, this minimal testing frequency is just twice the testing frequency currently available for suspected infections and medical staff in switzerland. second, while the latter tests require a high sensitivity with as few false positives and negatives as possible, random testing can very well be carried out with tests of much lower quality. indeed, a lower sensitivity acts as a systematic error in the estimate of the infection rate, which, however, drops out in the determination of its growth rate k. after the reboot at time t = further interventions will be necessary, as we assume that the reboot will have resulted in a positive growth rate k . in subsequent interventions, the policymakers try to take measures that aim at reducing the growth rate to zero. even if they had perfect knowledge of the current growth rate k(t), they would not succeed immediately since they do not know the precise quantitative effect of the measures they will take. nevertheless, had they the perfect knowledge of k(t), our model assumes that they would at least be able to estimate the effects to an extent such they would . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint not need to intervene more strongly than twice of what would be necessary to reduce with time k(t) to . this assumption implies that, if α is large, so that k(t) is known with relatively high precision at the time of intervention, the growth rate k is smaller than k in magnitude with high probability (tending rapidly to as α → ∞). the smaller α however, the more likely it becomes, that k(t) is overestimated, and a too big corrective measure is taken, which may destabilize the system. in this context, we observe that the ratio is a random variable with a distribution that is independent of ι in our model. to proceed, we assume that α is sufficiently large, i.e., such that the probability for ρ ι < to be true is indeed high. the second policy intervention occurs after a time that can be predicted along the same lines that lead to eq. ( c). one finds where ∆t is given by eq. ( a) . since, the growth rate k is likely to be smaller than k in magnitude, the third intervention takes place after yet a longer time span, etc. if we neglect that the fitted value k fit ι (t) differs slightly from k ι (a difference that is negligible when α ), our model ensures that ρ ι is uniformly distributed in [ , ]. after the ι-th intervention the growth rate is down in magnitude to to reach a low final growth rate k final , a typical number n int (k final ) of interventions are required after the reboot, where where the last approximation holds in the limit of large enough α. the time to reach this low rate is dominated by the last and first time intervals through the estimate thus, the system converges to the critical state where k = , but never quite reaches it. at late times t , the residual growth rate behaves as k final ∼ t − / . one uses eq. ( ) to reach this conclusion. the parameter α encodes the confidence policymakers need about the present state before they take a decision. here we discuss various measures that allow choosing an optimal value for α. as α decreases starting from large values, the time for interventions decreases, being proportional to α / according to eq. ( a). likewise the fluctuations of infection numbers will initially decrease. however, the logarithmic average − ln ρ ι in the denominator of eq. ( ) will also decrease from , and thus the necessary number of interventions increases. moreover, when α falls significantly below , interventions become more and more illinformed and erratic. it is not even obvious anymore that the marginally stable state is still approached asymptotically. from these two limiting considerations, we expect to be an optimal choice for α. let us now discuss a few quantitative measures of the performance of various strategies, which will allow policymakers to make an optimal choice of confidence parameter for the definition of a mitigation strategy. the time to reach a certain level of quiescence (low growth rates, infrequent interventions) is given by the time ( ), and thus by the expectation value of ∆t . as a measure for the political cost, c p , we may take the number of interventions that have to be taken to reach quiescence. as we saw in eq. ( ), it scales inversely with the logarithmic average of the ratios of growth rates, ρ, i.e., if restrictions are over-relaxed, the infection numbers will grow with time. the maximal fraction of infected people must never be allowed to rise above the manageable threshold of i c . this means that continuous (random) monitoring of the fraction of infected people is needed, so that given the knowledge from the time before the reboot, about the conditions under which the system can be stabilized, lock-down conditions can always be imposed at a time that is sufficient to prevent reaching the level of i c . beyond this consideration one may want to . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint keep the expected maximal increase of infection numbers low, which we take as a measure of health costs c h , note that as defined, c h is a stochastic number. its mean and tail distribution (for large r) will be of particular importance. imposing restrictions such that k < imply restrictions beyond what is absolutely necessary to maintain stability. if we assume that the economic cost c e is proportional to the excess negative growth rate, −k (and a potential gain proportional to k), a measure for the economic cost is the summation over time of −k(t), which converges, since k(t) decays as a sufficiently fast power law. hereto, c e is a stochastic variable that depends on the testing history and the policy measures taken. however, its mean and standard deviation give a good idea of the performance in terms of economic considerations. we introduced in sec. vi a feedback and control strategy to tune to a marginal state with vanishing growth rate k = after an initial reboot. interventions were only taken based on the measurement of the growth rate. however, in practice, a more refined strategy will be needed. in case the infection rate drops significantly below i * , one can safely afford to have a positive growth rate k. we thus assume that if i(t)/i * falls below some threshold i low = . , we intervene by relaxing some measures, that we assume to increase k by an amount uniformly distributed in [ , k ], but without letting k exceed the maximal value of k high = . . likewise, one should intervene when the fraction i(t) grows too large. we do so when i(t)/i * exceeds i high = . in such a situation we impose restrictions resulting in a decrease of k by a quantity uniformly drawn from [k high / , k high ]. the precise algorithm is given in appendix b. figure shows how our algorithm implements policy releases and restrictions in response to test data. the initial infected fraction and growth rate are i( ) = i c / = . and k = . , respectively, with a sampling interval of one day. to more easily demonstrate the feedback protocol, we employ a high value of α = and a number the unmitigated exponential growth with the initial growth rate k is also plotted as the black line. of r = tests per day, resulting in a higher confidence in the estimated growth rate and a longer time (> days) until intervention. figure a displays the infection fraction, u (t)/n , as a function of time, derived using our simple exponential growth model, which is characterized by a single growth rate that changes stochastically at interventions [eq. ( ) without the source term]. in the absence of intervention, the infected population would grow rapidly representing uncontrolled runaway of a second epidemic. at each time step (day) the infected fraction of the population is sampled. the result is normally distribution with mean and standard deviation given by eqs. ( e) and ( f) to obtain i(t). the former are represented by small circles, the latter by vertical error bars in fig. . if i/i * lies outside the range [i low , i high ], we intervene as described above. otherwise, on each day k fit (t) and its standard deviation are estimated using the data since the last intervention. with this, at each time step, eqs. ( m) to ( o) decide whether or not to intervene. in fig. , each red circle represents an intervention and therefore either a decrease or increase of the growth rate constant of our model. fig. shows the evolution of the fraction of infected . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. people. after an initial growth with rate k subsequent interventions reduce the growth rate down to low levels within a few weeks. at the same time the fraction of infected people stabilizes at a scale similar to i * -for the given parameter-set this is a general trend independent of realization. figure b displays the instantaneous value of the model rate constant and also the estimated value together with its standard deviation. the estimate follows the model value reasonably well. one sees that the interventions occur when the uncertainty in k is sufficiently small (given the large choice of α = ). we now assume that we have the capacity for r = per day, and assess the performance of our strategy as a function of the confidence parameter α in fig. . values of α ≤ lead to rapid, but at the same time erratic interventions, as is reflected by a rapidly growing number of interventions. for larger values of α, the time scale to reach a steady state increases while the economic and health costs remain more or less stable. a reasonable compromise between minimizing the number of interventions, and shortening the time to reach a steady state suggests a choice of α ≈ − . it is intuitive that the higher the number r of tests per day is, the better the mitigation strategy will perform. the characteristic time to reach a final steady state decreases as r − / , see eq. ( a). other measures for per- formance improve monotonically upon increasing r. this is confirmed and quantified in fig. , where we show how the political, health. and economic cost decreases with increasing test rate. after a reboot it is likely that the growth rate k jumps back to positive values, as we have always assumed so far. the time it takes until one can distinguish a genuine growth from intrinsic fluctuations due to the finite number of sample people depends on the growth rate k , see eq. ( a). in the worst case where the reboot brings back the unmitigated value k , one will know within - days with reasonable confidence that the growth rate is well above zero. this is shown in fig. . in such a catastrophic situation, an early intervention can be taken, while the number of infections has at most tripled at worst. this reaction time is - times much faster than without random testing! . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . fig. . time after which a significant positive growth rate is confirmed in the worst case scenario for which the growth rate k jumps to k = . after reboot. an intervention will be triggered in - days. results are shown for a confidence level α = and r = test a day. the circles are the mean values, the vertical lines indicate the standard deviations of the first intervention time. we have shown that the minimal testing rate r min ( ) is sufficient to obtain statistical information on the growth rate k as applied to switzerland as a whole. this assumes tacitly that the simple growth equation ( ) describes the dynamics of infections in the whole country well. that this is not necessarily a good description can be conjectured from recent data on the current rates with which numbers of confirmed infections in the various cantons grow. these data indeed show a very significant spread by nearly a factor of four suggesting that a spatially resolved approach is preferable, if possible. similar heterogeneity of the time evolution of infection numbers can even be seen within a single big city, such as london. if the testing capacity is limited by rates of order r min , the approach can still be used. but caution should be taken to account for spatial fluctuations corresponding to hot spots. one should preferentially test in areas that are likely to show the largest local growth rates so as not to miss locally super-critical growth rates by averaging over the entire country. if however, higher testing frequencies become available, new and better options come into play. valuable information can be gained by analyzing the test data not only for switzerland as a whole, but by distinguishing different regions. it might even prove useful not to lift restrictions homogeneously throughout the country, but instead to vary the set of restrictions to be released, or to adapt their rigor. by way of example, consider that after the spring vacation school starts in different weeks in different cantons. this regional difference could be exploited to probe the relative effect of re-opening schools on the local growth rates k. however, obviously, it might prove politically difficult to go beyond such "naturally" occurring differences, as it is with no doubt a complex matter to decide what region releases which measures first. a further issue is that the effects might be unclear at the borders between regions with different restrictions. there may also be complications with commuters that cross regional borders. finally, there may be undesired behavioral effects, if regionally varying measures are declared as an "experiment". such issues demand careful consideration if regionally varying policies are applied. even if policy measures should eventually not be taken in a region-specific manner, it is very useful to study a regionally refined model of epidemic dynamics. indeed a host of literature exists that studies epidemiological models on lattices and analyzes the spatial heterogeneities. [ , ] in certain circumstances those have been argued to become even extremely strong. [ ] in the present paper, we will content ourselves with a few general remarks concerning such refinements. we reserve a more thorough study of regionally refined testing and mitigation strategies to a later publication. let us thus group the population of switzerland into g sets. the most natural clustering is according to the place where people live, cities or counties. the more we partition the country, the more spatially refined the acquired data will be, and the better tailored mitigation strategies could potentially become. however, this comes at a price. namely, for a limited national testing rate r tot , an increased partitioning means that the statistical uncertainty to measure local growth rates in each region will increase. the minimal test rate r min that we estimated on the right-hand side of eq. ( ) still holds, but now for each region, which can only test at a rate r = r tot /g. to refine switzerland g regions we thus have the constraint that the total testing capacity exceeds on the other hand, if testing at a high daily rate r tot becomes available, nothing should stop one to refine the statistical analysis to g ≈ r tot /r min to make the best use of available data. one might also consider other distinguishing characteristics of groups (age or commuting habits, etc.), but we will not do so here, since it is not clear whether the increased complexity of the model can be exploited to reach an improved data analysis. in fact we expect that the number of fitting parameters will very quickly become too large by making such further distinctions. . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint b. spatially resolved growth model each of the population groups m ∈ { , · · · , g} is assumed to have roughly the same size, containing people, u m of whom are infected, but yet undetected. the spreading of infections is again assumed to follow a linear growth equation (where we neglect influx from across the borders from the outset) ( ) here, the growth kernel k(t) is a g × g matrix with matrix elements k mn (t). the matrix k(t) has g (complex valued) eigenvalues λ n , n = , · · · , g. the largest growth rate is given by for the sake of stability criteria, κ(t) now essentially takes the role of k(t) in the model with a single region, g = . we note that the number of infections grows exponentially if κ(t) > , and decreases if κ(t) < . as in the case of a single region, we assume k(t) to be piece wise constant in time, and to change only upon taking policy interventions. in the simplest approximation, one assumes no contact between geographically distinct groups, that is, the offdiagonal matrix elements are set to zero [k m =n (t) = ] and the eigenvalues become equal to elements of the diagonal: k m (t) ≡ k mm (t). as current cantonal data suggests, the local growth rate k m (t) depends on the region, and thus k m (t) = k n (t). it is natural to expect that k m (t) correlates with the population density, the fraction of the population that commutes, the age distribution, etc. if on top of the heterogeneity of growth rates one adds finite but weak inter-regional couplings k m =n (t) > (mostly between nearest neighbor regions), one may still expect the eigenvectors of k(t) to be rather localized (a phenomenon well known as anderson localization [ ] in the context of waves propagating in strongly disordered media). by this, one means that the the eigenvectors have a lot of weight on few regions only, and little weight everywhere else. that such a phenomenon might occur in the growth pattern of real epidemics is suggested by the significant regional differences in growth rates that we have mentioned above. in such a situation it would seem preferable to adapt restrictive measures to localized regions with strong overlap on unstable eigenvectors of k(t), while minimizing their socio-economic impact in other regions with lower k m (t). c. mitigation strategies with regionally refined analysis as mentioned above, in the case with several distinct regions, g > , an intervention becomes necessary when the largest eigenvalue κ(t) of k(t) crosses an upper or a lower threshold (with a level of confidence α again to be specified). if the associated eigenvector is delocalized over all regions, one will most likely respond with a global policy measure. however, it may as well happen that the eigenvector corresponding to κ(t) is well-localized. in this case one can distinguish two strategies for intervention: (a) global strategy one always applies a single policy change to the whole country. this is politically simple to implement, but might incur unnecessary economic cost in regions that are not currently unstable. (b) local strategy one applies a policy change only in regions which have significant weight on the unstable eigenvectors. this means that one only adjusts the corresponding diagonal matrix elements of k(t) and those off-diagonals that share an index with the unstable region. likewise, regions that have i m < i * and have negligible overlap with eigenvectors whose eigenvalues are above κ − , could relax some restrictions before others do. fitting test data to a regionally refined model will allow us to estimate the off-diagonal terms k mn (t), which are so far poorly characterized parameters. however, the k mn (t) contain valuable information. for instance, if a hot spot emerges [that is, a region overlapping strongly with a localized eigenvector with positive re λ n (t)], this part of the matrix will inform which connections are the most likely to infect neighboring regions. they can then be addressed by appropriate policy measures and will be monitored subsequently, with the aim to contain the hot spot and keep it well localized. this model allows us to calculate again economic, political, and health impact of various strategies. it is important to assess how the global and the local strategy perform in comparison. obviously this will depend on the variability between the local growth rates k m (t), which is currently not well known, but will become a measurable quantity in the future. at that point one will be able to decide whether to select the politically simpler route (a) or the heterogeneous route (b) which is likely to be economically favorable. we are currently engaged in developing an analysis tool to quickly process test data for multi-region modelling. we are developing and assessing intervention strategies with the perspective of running it daily with the best available current data and knowledge. we will report on these activities in subsequent memoranda. . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint we have analyzed a feedback and control model for managing a pandemic such as that caused by covid- . the crucial output parameters are the infection growth rates in the general population and spatially localized sub-populations. when planning for an upcoming reboot of the economy, it is essential to assess and mitigate the risks of relaxing some of the restrictions that have brought the covid- epidemic under control. in particular, the policy strategy chosen must suppress a potential second exponential wave when the economy is rebooted, and so avoid a perpetual stop-and-go oscillation between relaxation and lockdown. feedback and control models are designed with precisely this goal in mind. having random testing in place, the risk of a second wave can be kept to a minimum. additional testing capacity of r min = day − tests (on top of the current tests for medical purposes) carried out with randomly selected people would allow us to follow the course of the pandemics almost in real time, without huge time delays, and without the danger of increasing the number of infected people by more than a factor of two, if our intervention strategy is followed. if testing rates r significantly higher than r min become available, a regionally refined analysis of the growth dynamics can be carried out, with g ≈ r/r min regions that can be distinguished. in the worst case scenario, where releasing certain measures immediately make the country jump back to the unmitigated growth rate of k = . day − , random testing would detect this within - days from the change coming into effect. this is in stark contrast to the nearly days of delay required for symptomatic individuals to emerge in statistically significant numbers. after such a time delay a huge increase (a factor of order ) of infection numbers may have already occurred, which would be catastrophic. daily random testing safely prevents this. thereby the significant reduction of the time delay is absolutely crucial. note that without daily polling of infection numbers and without knowledge about the quantitative effect of restriction measures, a reboot of the economy could not be risked before the number of infections has been suppressed by at least a factor of - below the current level. given the limits of suppression rates that can be achieved without most draconic lockdown measures, this will require a very long time and thus translates into an enormous economic cost. in contrast, daily polling will allow us to carefully reboot the economy and adjust restrictive measures, while closely monitoring their effect. since the reaction times are so much shorter, one can safely start an attempted reboot already at infection numbers corresponding roughly to the status quo. at some point one might consider the option to start releasing different sets of restrictions in different regions, with the aim to learn faster about their respective effects and thus to optimize response strategies in subsequent steps. we are grateful to emma slack, giulia brunelli, and thomas van boeckel for helpful discussions, and the erc hero project for supporting ga. appendix a: assessment of contact tracing as a means to control the pandemics let us briefly discuss the strategy of so-called contact tracing as a means to contain the pandemics, as has been discussed in the literature [ ] . we argue that contact tracing is a helpful tool to suppress transmission rates, but is susceptible to fail when no other method of control is used. contact tracing means that once an infected person is detected, people in their environment (i.e., known personal contacts, and those identified using mobile-phone based apps etc) are notified and tested, and quarantined if detected positive. as a complementary measure to push down the transmission rate, it is definitely useful, and it represents a relatively low cost and targeted measure, since the probability to detect infected people is high. however, as a sole measure to contain a pandemic contact tracing is impractical (especially at the current high numbers of infected people) and even hazardous. the reason is as follows. it is believed that a considerable fraction f asym of infected people show only weak or no symptoms, so that they would not get tested under the present testing regime. the value of f asym is not well known, but it might be rather high ( % or even much higher). such asymptomatic people will go undetected, if they have not been in contact with a person displaying symptoms. if on average they infect r people while being infectious, and if r f asym > , there will be an exponential avalanche of undetected cases. they will produce an exponentially growing number of detectable and medically serious cases. the contact tracing of those (upward in the infection tree) is tedious, and cannot fully eliminate the danger of such an avalanche. contact tracing as a main strategy thus only becomes viable once the value of f asym is well established, and one is certain to be able to control the value of r such that r f asym < . • t = , , · · · : time in days (integer). . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint • n int : number of interventions (including the reboot at t = ). • t int (j): first day on which the j'th rate k j applies. on day t int ( ) ≡ the initial reboot step is taken. • ∆t(j) = t int (j + ) − t int (j): time span between interventions j and j + . • t first : first day on which the current rate k = k(t) applied. • i(t): fraction of infected people on day t. • k(t): growth rate on day t. • r: number of tests per day. • c h : health cost. • c e : economic cost. • k min = . : minimal growth rate targeted. • i low = . : lower threshold for i/i * . if i/i * < i low , no intervention is made even if k is above α δk. • i high = : upper threshold for i/i * . if i/i * > i high , an intervention is made even if k is still smaller than α δk. • k low = − . : minimal possible decreasing rate considered. • k high = . : maximal possible increasing rate considered. • t min = : minimal time to wait since the last intervention, for interventions based on the level of i(t). • b = . : parameter defining the possible range of changes ∆k due to measures taken after estimating k. |∆k/k est | ∈ [b, ]. • α: confidence parameter. • n (t): cardinality of random sample of infected people on day t. the number n (t) is obtained by sampling from a gaussian distribution of mean i(t) r and standard deviation i(t) r and rounding the obtained real number to the next non-negative integer. • t first = t int ( ) = . • n int = . • c h = . • c e = . • k( ) = k = . . (initial growth rate) • i( ) = i * . common choice i * = i c / = . . • draw n ( ). • k( ) = k( ). (no intervention at the end of day ) • set t = . define i(t) = i(t − ) e k (t− ) , define c h = max{c h , i(t)/i * }, determine what will be k(t + ), by assessing whether or not to intervene: if t = t first , then k(t + ) = k(t). (no intervention) else distinguish three cases: . if i(t)/i * < i low and t − t first ≥ t min , then k(t + ) = min{k(t) + x k , k high } with x = unif[ , ]. . if i(t)/i * > i high and t − t first ≥ t min , then k(t + ) = max{k(t) − ( + x)/ k high , k low } with x = unif[ , ]. . if i low < i(t)/i * < i high , then • set ∆t ≡ t − t first + • compute k est (t first , ∆t), and δk est (t first , ∆t) using sec. b . if |k est | > k min and [k est > α δk est or k est < −α δk est ], set k(t + ) = k(t) − xk est with x = unif[b, ]. if k(t + ) > k high , put k(t + ) = k high . if k(t + ) < k low , put k(t + ) = k low . else k(t + ) = k(t), t = t + . if an intervention was taken above: put n int = n int + . define t int (n int ) = t + . define ∆t(n int − ) = t int (n int ) − t int (n int − ). set t first = t + . . cc-by-nc-nd . international license it is made available under a author/funder, who has granted medrxiv a license to display the preprint in perpetuity. is the (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint if |k est | < k min and k(t) < k min and t − t first > , exit. else return to daily routine for next day. computing k est (t first , ∆t) and δk est (t first , ∆t): if ∆t is even: define n (t first + ∆t/ + m). • else return k est = , δk est = . if ∆t is odd: n (t first + (∆t + )/ + m), • else return k est = , δk est = . time to first intervention: ∆t( ) health cost: c h political cost: n int economic cost c e strategies for mitigating an influenza pandemic covid- reports from the mrc centre for global infectious disease analysis impact of non-pharmaceutical interventions (npis) to reduce covid- mortality and healthcare demand cybernetics: or control and communication in the animal and the machine the reproductive number of covid- is higher compared to sars coronavirus infectious diseases of humans; dynamic and control epidemic modeling: an introduction stochastic epidemic models: a survey the number of icu beds in switzerland was taken from the neue zürcher zeitung from march on the critical behavior of the general epidemic process and dynamical percolation epidemic models and percolation infinite-randomness critical point in the twodimensional disordered contact process absence of diffusion in certain random lattices the efficacy of contact tracing for the containment of the novel coronavirus (covid- ) coronavirus: policy design for stable population recovery: using feedback to maximize population recovery rate while respecting healthcare capacity key: cord- - sl ap authors: bousquet, jean; anto, josep m.; iaccarino, guido; czarlewski, wienczyslawa; haahtela, tari; anto, aram; akdis, cezmi a.; blain, hubert; canonica, g. walter; cardona, victoria; cruz, alvaro a.; illario, maddalena; ivancevich, juan carlos; jutel, marek; klimek, ludger; kuna, piotr; laune, daniel; larenas-linnemann, désirée; mullol, joaquim; papadopoulos, nikos g.; pfaar, oliver; samolinski, boleslaw; valiulis, arunas; yorgancioglu, arzu; zuberbier, torsten title: is diet partly responsible for differences in covid- death rates between and within countries? date: - - journal: clin transl allergy doi: . /s - - - sha: doc_id: cord_uid: sl ap reported covid- deaths in germany are relatively low as compared to many european countries. among the several explanations proposed, an early and large testing of the population was put forward. most current debates on covid- focus on the differences among countries, but little attention has been given to regional differences and diet. the low-death rate european countries (e.g. austria, baltic states, czech republic, finland, norway, poland, slovakia) have used different quarantine and/or confinement times and methods and none have performed as many early tests as germany. among other factors that may be significant are the dietary habits. it seems that some foods largely used in these countries may reduce angiotensin-converting enzyme activity or are anti-oxidants. among the many possible areas of research, it might be important to understand diet and angiotensin-converting enzyme- (ace ) levels in populations with different covid- death rates since dietary interventions may be of great benefit. a novel strain of human coronaviruses, the severe acute respiratory syndrome coronavirus (sars-cov- ), named by the international committee on taxonomy of viruses (ictv) [ ] , has emerged and caused an infectious disease referred to as "coronavirus disease " (covid- ) by the world health organization (who) [ ] . covid- has aggressively spread across the globe and over , deaths have been reported. however, there appears to be high-and low-death rate countries. after the outbreak in china, covid- has also affected europe after becoming a pandemic. interestingly, there is large variability across european countries in both incidence and mortality, and most current debates on covid- focus on the differences among countries. german fatalities are strikingly low as compared to many european countries. among the several explanations proposed, an early and large testing of the population was put forward [ ] . however, little attention has been given to regional differences and diet [ ] . according to the johns hopkins coronavirus resource center (https ://coron aviru s.jhu.edu), one of the most important ways of measuring the burden of covid- is mortality. however, death rates are assessed differently between countries and there are many biases that clinical and translational allergy are almost impossible to assess. differences in the mortality rates depend on the characteristics of the health care system, the reporting method, whether or not deaths outside the hospital have been counted and other factors, many of which remain unknown. countries throughout the world have reported very different case fatality ratios-the number of deaths divided by the number of confirmed cases-but these numbers cannot be compared at all due to biases. on the other hand, for many countries, the methodology reporting death rates in the different regions is standardized across the country. we used the johns hopkins coronavirus resource center to assess death rates at the national level (https ://coron aviru s.jhu.edu). the current death rate per million people in europe shows different trends. germany has a low death rate, but austria, the czech republic, poland, slovakia, the baltic states and finland have similar or lower rates. on the other hand, belgium, france, italy, spain and the uk have higher rates (fig. ). large differences exist when assessing death rates within a country. in germany, bavaria started the earliest tests but was and still is the most affected region (fig. ) . death rates per million range from in mecklenburg-vorpommern to in bavaria. in switzerland, the french and italian speaking cantons have a far higher death rate than the german-speaking ones ( fig. ) (office fédéral de la santé publique, switzerland, https ://www.bag.admin .ch/bag/fr/home.html). in high-rate countries such as spain, large variations also exist within the country, but the numbers range from in murcia to over in madrid. most diseases exhibit large geographical variations which frequently remain unexplained despite abundant research [ ] . covid- will not be an exception. though the more relevant factors are likely to be seasonal variations, immunity, cross-immunity, intensity, timing of measures [ ] , type, onset, duration and measures of protection, other factors like environment or nutrition should not be overlooked. obesity, a risk factor of mortality in covid- , suggests the importance of nutrition [ ] . the "low-rate" european countries have used different quarantine and/or confinement times and methods and none have performed as many early tests as germany. thus, although the german testing approach is very important [ ] , other factors may also be significant. although there are large differences between countries in death rates, the age-dependent severity of covid- is similar between asian, european and american countries. the rate of deaths is increased in the older population. globally, there are risk factors for death including obesity and type diabetes. a strong relationship between hyperglycemia, impaired insulin pathway, and cardiovascular disease in type diabetes is linked to oxidative stress and inflammation [ ] . lipid metabolism has an important role to play in obesity, diabetes and its multi-morbidities, and the ageing process [ ] . dietary fatty acids have a significant role in immune responses [ ] . many foods have an antioxidant activity [ ] [ ] [ ] . resveratrol, present in many foods [ ] , is an inhibitor of mers-coronavirus infection [ ] . the angiotensin-converting enzyme (ace ) has multiple physiological roles: a negative regulator of the reninangiotensin system, facilitator of amino acid transport, and the sars-cov and sars-cov- receptor [ ] . ace converts angiotensin i to angiotensin ii but ace catalyses the conversion of angiotensin ii to angiotensin and is also the main entry point for coronavirus into cells. differences between countries in ace have been associated with genetic patterns. the ace d allele increased risk of vasculitis [ ] or hypertension [ ] . the ace i/d polymorphism is involved in the onset of type diabetes [ ] and might be associated with susceptibility to peripheral vascular diseases in the asian population [ ] . however, dietary patterns have a strong effect on ace levels. a high-saturated fat diet increases ace [ ] . many foods have an ace-inhibitory activity [ ] [ ] [ ] . antioxidant activities and ace inhibition have been largely found in many foods [ ] . moreover, ace levels in blood are highly and rapidly sensitive to food intake [ ] . identifying whether countries with high or low ace activity have different death rates would be of great interest in understanding the clinical importance of interventions. however, the available evidence, in particular from human studies, does not seem to support the hypothesis that inhibitors of ace or renin-angiotensin-aldosterone (acei/arb) drugs increase the ace expression and the risk of covid- [ ] . this might suggest that changes in ace expression (inhibition/stimulation) might not be as relevant as previously thought and other diet-related changes might be more (or equally) important. germany, austria, croatia, the czech republic, poland, slovakia, the baltic states and german-speaking swiss cantons exhibit lower covid- mortality rates than france, italy, spain, and the french and italian speaking swiss cantons. among many factors, diet differs considerably between these low-or high-mortality countries. it appears that death rates in germany are higher in the two southern regions as well as in saarland than elsewhere. baden-wurttemberg and saarland are in close contact with alsace (france), and the higher infection rate may be due to the high cross-border traffic of the french. however, this was not the case for rhineland-palatinate (lower death rate), possibly because the east region of france was contaminated later. in addition, saarland is a special case as half of the deaths, unlike in the other german states, occurred in only a few longterm care facilities where a high number of people were infected in a short time and all deaths during the episode were attributed to corona without autopsies being made. this potential french-based contamination does not apply for bavaria (earliest german region to be contaminated and highest death rate). diet differs within germany, the southern states traditionally having a higher fat-rich diet. diet is not normally distributed within country/region, which can be an additional argument in favour of the uneven distribution of mortality. nutrition may therefore play a role in the immune defense against covid- and may explain some of the differences seen in covid- across europe. it will be needed to test dietary differences between low and highrate countries. foods with potent antioxidant or anti ace activity-like uncooked or fermented cabbage [ ] [ ] [ ] are largely consumed in low-death rate european countries, korea and taiwan, and might be considered in the low prevalence of deaths. although it is difficult to compare health systems and death reporting across european countries, bulgaria, greece and romania have very low death rates. this might also be associated with diet since cabbage (romania) and fermented milk (bulgaria and greece) are common foods. the latter food is a known ace natural inhibitor [ ] . turkey, another apparently low-death rate country, also consumes a lot of cabbage and fermented milk products. another example may be the food supply chain. the increasing availability of foods from big retail is a revolutionary event that has impacted crops (favouring those that have the best ratio of effectiveness over costs of production) and health at a population-size level. in particular, such a change in food availability has altered alimentary habits-promoting sugar-enriched, vitamindepauperated foods-and has become one of the causes of the obesity epidemic, especially among adolescents. these foods come from centralized farms in selected areas of the world that are distributed around the planet, elongating the supply chain of food. the impact of long supply chain of food on health is measurable by an increase in metabolic syndrome and insulin resistance [ ] . therefore, rural areas that are more prone to short supply food may have been able to better tolerate the covid- pandemia, with a lower death toll. these considerations may be partly involved in lower death rates in southern italy compared to the northern part. understanding the within and between country differences in covid- will be of paramount importance in understanding covid- risk and protective factors, and will eventually help to control the epidemics. we acknowledge that many factors may play a role in the extension and severity of covid- , such as trained immunity of the population, early and fast education, rapid organization and adaptation of the hospitals and the public, preparedness for pandemics and public hygiene. diet represents only one of the possible causes of the covid- epidemic and its importance needs to be better assessed. the species severe acute respiratory syndrome-related coronavirus: classifying -ncov and naming it sars-cov- . nat microbiol intranasal corticosteroids in allergic rhinitis in covid- infected patients: an aria-eaaci statement covid- : why germany's case fatality rate seems so low rapid response: why germany's case fatality rate seems so low: is nutrition another possibility geographic variations in the effect of atopy on asthma in the european community respiratory health study projecting the transmission dynamics of sars-cov- through the postpandemic period high prevalence of obesity in 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enzyme gene polymorphism affect blood pressure? findings after years of follow-up in healthy subjects is the influence of variation in the ace gene on the prospective risk of type diabetes in middle-aged men modified by obesity? ethnic differences in the association between angiotensin-converting enzyme gene insertion/deletion polymorphism and peripheral vascular disease: a meta-analysis high-saturated-fat diet increases circulating angiotensin-converting enzyme, which is enhanced by the rs polymorphism defining persons at risk of nutrient-dependent increases of blood pressure food-originating ace inhibitors, including antihypertensive peptides, as preventive food components in blood pressure reduction. comprehens rev food sc food safety food-derived bioactive peptides and their role in ameliorating hypertension and associated cardiovascular diseases molecular interactions, bioavailability, and cellular mechanisms of angiotensin-converting enzyme inhibitory peptides association of angiotensin-converting enzyme insertion/deletion polymorphism with susceptibility to systemic lupus erythematosus: a meta-analysis angiotensin converting enzyme (ace): a marker for personalized feedback on dieting renin-angiotensin-aldosterone system inhibitors and risk of covid- in vitro and in vivo studies on the angiotensin-converting enzyme inhibitory activity peptides isolated from broccoli protein hydrolysate antioxidant components of brassica vegetables including turnip and the influence of processing and storage on their anti-oxidative properties kimchi and other widely consumed traditional fermented foods of korea: a review anti-hypertensive peptides released from milk proteins by probiotics we are what we eat: impact of food from short supply chain on metabolic syndrome publisher's note springer nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations key: cord- -t c drft authors: chiyomaru, katsumi; takemoto, kazuhiro title: global covid- transmission rate is influenced by precipitation seasonality and the speed of climate temperature warming date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: t c drft the novel coronavirus disease (covid- ) became a rapidly spreading worldwide epidemic; thus, it is a global priority to reduce the speed of the epidemic spreading. several studies predicted that high temperature and humidity could reduce covid- transmission. however, exceptions exist to this observation, further thorough examinations are thus needed for their confirmation. in this study, therefore, we used a global dataset of covid- cases and global climate databases and comprehensively investigated how climate parameters could contribute to the growth rate of covid- cases while statistically controlling for potential confounding effects using spatial analysis. we also confirmed that the growth rate decreased with the temperature; however, the growth rate was affected by precipitation seasonality and warming velocity rather than temperature. in particular, a lower growth rate was observed for a higher precipitation seasonality and lower warming velocity. these effects were independent of population density, human life quality, and travel restrictions. the results indicate that the temperature effect is less important compared to these intrinsic climate characteristics, which might thus be useful for explaining the exceptions. however, the contributions of the climate parameters to the growth rate were moderate; rather, the contribution of travel restrictions in each country was more significant. although our findings are preliminary owing to data-analysis limitations, they may be helpful when predicting covid- transmission. the novel coronavirus disease (covid- ) became a rapidly spreading worldwide epidemic; thus, it is a global priority to reduce the speed of the epidemic spreading. several studies predicted that high temperature and humidity could reduce covid- transmission. however, exceptions exist to this observation, further thorough examinations are thus needed for their confirmation. in this study, therefore, we used a global dataset of covid- cases and global climate databases and comprehensively investigated how climate parameters could contribute to the growth rate of covid- cases while statistically controlling for potential confounding effects using spatial analysis. we also confirmed that the growth rate decreased with the temperature; however, the growth rate was affected by precipitation seasonality and warming velocity rather than temperature. in particular, a lower growth rate was observed for a higher precipitation seasonality and lower warming velocity. these effects were independent of population density, human life quality, and travel restrictions. the results indicate that the temperature effect is less important compared to these intrinsic climate characteristics, which might thus be useful for explaining the exceptions. however, the contributions of the climate parameters to the growth rate were moderate; rather, the contribution of travel restrictions in each country was more significant. although our findings are preliminary owing to data-analysis limitations, they may be helpful when predicting covid- transmission. the world-wide spreading of coronavirus disease (covid- ) [ when and more cases were confirmed in cumulative counts, as described previously [ ]. we confirmed that similar conclusions were obtained at the different cut-off values (using the data within days starting from the date when and more cases were confirmed). we obtained climate parameters from several databases based on the observation area latitudes and longitudes available in the dataset [ ] . was also considered to remove spatial autocorrelation in the regression residuals. specifically, the moran eigenvector approach was adopted using the function spatialfiltering in the r package spatialreg (version . . ). as with the ols regression analysis, full models were constructed, and then the best model was selected based on aicc values. the spatial filter was fixed in the model-selection procedures [ ] . the contribution (i.e., non-zero estimate) of each explanatory variable to the growth rate of covid- cases was considered significant when the associated p-value was less than . . the data in areas were investigated (figure ). the ols regression analysis (table ) and spatial analysis ( and argentina were warm in march; however, they show low precipitation seasonality ( figure ) . thus, the spreads might occur in these areas. moreover, europe and the usa might have undergone rapid spreads because they show low precipitation seasonality; on the other hand, the spread might have reached a peak relatively quickly in china because of relatively high precipitation seasonality. the contribution of solar radiation is currently ambiguous. solar radiation showed a positive association with the growth rate of covid- cases. however, the results were less robust; in particular, the contribution was statistically significant in spatial analysis (table ), but not in the full and averaged models in the ols regression (table ) . thus, it remains possible that the contributions partly observed in the analyses are artefacts. assuming the positive association, the result is inconsistent with the fact that solar (uv) radiation is expected to reduce infection disease (e.g., influenza) transmission [ ]. moreover, a pairwise correlation analysis showed no association between the growth rate and solar radiation (spearman's rank correlation coefficient r = - . , p = . ). the contributions of wind speed and precipitation were also limited. this is inconsistent with previous studies [ , ] ; however, statistical significances were not evaluated in these studies. this discrepancy might be due to differences in the data analyses between this study and previous studies. in particular, previous studies used the measures based on the number of confirmed cases; however, these measures may be affected by the difference of covid- testing between areas. hence, further examinations may be needed, given the importance of these climate parameters in infectious disease transmission [ , ] . non-climate parameters were also associated with the growth rate of according to the estimates of the models of the ols regression analysis and spatial analysis, the contribution of travel restrictions was most significant than those of the climate parameters; in particular, travel restrictions showed a negative association with the growth rate. this result may be an extension of the result that the reduction of tables table . influence of explanatory variables on the growth rate of covid- cases based on the ordinary least squared regression approach. the results of the full model, best model, and averaged model are shown, respectively. the abbreviations of variables are as follows: tmean (monthly mean temperature), dtr (monthly diurnal temperature range), tseasonality (temperature seasonality), pseasonality (precipitation seasonality), uv (monthly solar radiation index), wv (warming velocity), pd (population density), hdi (human development index), and ban (travel restrictions). r denotes the coefficient of determination for full and best models based on the ols regression. se is the standard error. values in brackets are the associated p-values. full . cc-by-nc-nd . international license it is made available under a is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. (which was not peer-reviewed) the copyright holder for this preprint . https://doi.org/ . / . . . doi: medrxiv preprint an interactive web-based dashboard to track covid- in real time clinical features of patients infected with novel coronavirus in wuhan why inequality could spread covid- high temperature and high humidity reduce the transmission of covid- the impact of temperature and absolute humidity on the coronavirus disease (covid- ) outbreak -evidence from china role of temperature and humidity in the modulation of the doubling time of covid- cases temperature dependence of covid- transmission roles of meteorological conditions in covid- transmission on a worldwide scale spread of sars-cov- coronavirus likely to be constrained by climate preliminary evidence that higher temperatures are associated with lower incidence of covid- , for cases reported globally up to th temperature significant change covid- transmission in cities influenza seasonality: lifting the fog environmental role in influenza virus outbreaks effects of temperature, humidity, and diurnal temperature range on influenza incidence in a temperate region. influenza other respi viruses urbanization and humidity shape the intensity of influenza epidemics in u.s. cities changing rapid weather variability increases influenza epidemic risk in a warming climate seasonality and the dynamics of infectious diseases human impacts and climate change influence nestedness and modularity in food-web and mutualistic networks decomposing the effects of ocean environments on predator-prey body-size relationships in food webs network resilience of mutualistic ecosystems and environmental changes: an empirical study methods to account for spatial autocorrelation in the analysis of species distributional data: a review the effect of human mobility and control measures on the covid- epidemic in china an investigation of transmission control measures during the first days of the covid- epidemic epidemic curves made easy using the r package incidence global covid- transmission rate is influenced by precipitation seasonality and the speed of climate temperature warming very high resolution interpolated climate surfaces for global land areas macroecological trends in nestedness and modularity of seed-dispersal networks: human impact matters the influence of late quaternary climate-change velocity on species endemism population density, revision the human footprint and the last of the wild gridded global datasets for gross domestic product and human development index over - . sci data model selection and information theory in geographical ecology age specificity of cases and attack rate of novel coronavirus disease (covid- ) the authors would like to thank editage (www.editage.com) for english language editing. key: cord- -a ldr mn authors: odendaal, willem g title: method for active pandemic curve management (mapcm) date: - - journal: nan doi: . / . . . sha: doc_id: cord_uid: a ldr mn the covid- pandemic of prompted stringent mitigation measures to "flatten the curve" quickly leading to an asphyxiated us economy as a national side effect. there are severe drawbacks to this strategy. the resulting flattened curve remains exponential and always under utilizes available healthcare capacity with a chance of still overburdening it. moreover, while a mitigation strategy involving isolation and containment can scale down infections, it not only prolongs the outbreak significantly, but also leaves a susceptible population in its wake that's ripe for a secondary outbreak. since economic activity is inversely proportional to mitigation, curtailing the outbreak with sustained mitigation can stifle the economy severely with disastrous repercussions. full mitigation for the duration of an outbreak is therefore unsustainable and, overall, a poor solution with potentially catastrophic consequences that could've been avoided. a new strategy, coined a "method for active pandemic curve management", abbreviated mapcm, presented herein can shape the outbreak curve in a controlled manner for optimal utilization of healthcare resources during the pandemic, while drastically shortening the outbreak duration compared to mitigation by itself without trading off lives. this method allows mitigation measures to be relaxed gradually from day one, which enables economic activity to resume gradually from the onset of a pandemic. since outbreak curves (such as hospitalizations) can be programmed using this method, they can also be shaped to accommodate changing needs during the outbreak; and to build herd immunity without the damaging side effects. the method can also be used to ease out of containment. mapcm is a method and not a model. it is compatible with any appropriate outbreak model; and herein it is illustrated in examples using a hybrid logistic model. from this "flattened" curve: to this programmable curve: strengths: • slows down the outbreak • reduces infection rate (the total percentage of population infected) • shrinks (scales down) the original curve • buys time (seasonal damping, finding cure, preparing healthcare, etc.) • potentially reduces fatality rate remaining weaknesses: • remains exponential • still has a high peak • can still overburden available healthcare capacity around its peak • under-utilizes available healthcare capacity for long periods before and after peak • still costs too many lives that could have been saved • prolongs the outbreak for too long • high cost of containment for entire country • unsustaibable -economy frozen and in free fall being controlled by the outbreak pros: • programmable curve in amplitude and duration • customizable to meet available resources • eliminates the exponential peak • optimizes utilization of healthcare capacity • reduces fatality rate through better healthcare • shortens outbreak duration & disruption to normal life • minimizes the cost of containment • does not keep economy at standstill • gradually brings economy back online from day one • not magic! this is engineering. • has never been done for a pandemic before • diminishing returns the later this method is implemented • uncertainties due to stochastics and the human factor controlling the outbreak all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint when the covid- pandemic broke out it soon became clear that the healthcare systems in possibly every country in the world would be crippled by an overwhelming need for hospitalization exceeding the available resources and supply chains. while many vital characteristics of the pathogen are still unclear it appears that the virus is as deadly as it is contagious. the actual fatality rate hasn't fully crystalized yet due to insufficient testing. some speculate fatality rates well below %. even if the fatality rate is close to that of influenza, this virus distinguishes itself by concentrating annual totals for deaths and critical care needs into a matter of weeks. a worrying statistic is the death rate among resolved cases, which is varying between % to over %. the most popular strategy implemented by government leaders to address these problems came down to aggressive containment, sometimes aborderlining draconian laws, at a national level to "flatten the curve". the idea is to slow down the spread, reduce the infection rate, and close the gap between the excessive demand and the available healthcare resources. however, the level of mitigation required to flatten the curve can asphyxiate an economy due to layoffs and closing businesses. to make matters worse, flattening the curve also prolongs the outbreak for an unsustainable amount of time. moreover, the flattened curve might still exceed healthcare capacity, as it maintains its exponential character despite being damped. in fact, it is unlikely, if not impossible to reduce the curve within available healthcare resource thresholds. the question then becomes whether it is possible to shrink the gap between hospitalizations and available healthcare capacity while keeping healthy economic activity without sacrificing lives. in this paper it will be shown that it is not only possible, the curve can also be programmable using a method for active pandemic curve management (mapcm). this is accomplished by considering this complex problem from an engineering systems perspective and implementing a quasi-open-loop control scheme using existing mitigation mechanisms to curb the pandemic outbreak in a controlled way. mapcm will be counter-intuitive for most people, especially those in the healthcare professions. however, equally counterintuitive control methods do exist in existing electrical industrial and military products and applications. please note that the focus of this paper is to present a new method, not a model. the models and numbers used in the rest of the paper are unimportant and can be substituted by any other suitable models, simulations, or other constructs. for illustration purposes a hybrid logistic model for the covid- pandemic will be applied to paper studies of the situation in the usa by way of a few examples. note that the reproductive number, r o , is defined in this paper as the number of people infected per person per day: where f (d) is the relevant cumulative figure on day d during the initial stages of the outbreak. (a) economic activity vs. full mitigation (b) economic activity vs. controlled mitigation. travel bans and aggressive containment strategies did have an effect on slowing down the spreading of covid- . since the outbreak caught the entire world exccept china by surprise, the ability to buy some time by imposing mitigation measures is certainly desirable, especially in view of the absense of any useful information about the disease, however, the cost of aggressive mitigation for even a short amount of time is stupendous. the stock market plunged within a day of announcing even mild mitigation through voluntary self-isolation in the united states. closing business for all but essential functions lead to layoffs and skyrocketing unemployment that could have serious consequences for any country. it quickly became apparent that these outbreak mitigation strategies: ) are inversly proportional to economic health (see figure ), ) are extremely costly, and all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . ) suspending economic activity over even brief periods of time carry excessive cost. sustained mitigation to flatten the curve is the worst of both worlds from an economic perspective as shown in figure (a). not only is the economic activity halted thus pushing an otherwise healthy economy into freefall, it also prolongs it well beyond the herd immunity situation. as shown in figure (b) mapcm can start off with similar levels of mitigation, but immediately starts lifting them gradually which eases the economy back to normal from day one. a disappointing outcome of these increasinly stringent containment strategies is that while the outbreak curves are indeed being scaled down, they aren't flattened by much. in fact, the curves for projected hospitalizations with full mitigation remain exponential with peak amplitudes that still exceed available healthcare capacities as shown in figure and again in figure , which depicts new cases being reported daily under a few different strategies. in figure the "flattened" curve still overwhelms available staffed beds during and around the peak period. however, notice that the curve has two long tail ends in the front and rear during which the capacity is severely underutilized. in this example a normalized reproductive number , r o = . , was used (based on a curve-fit from the usa data before a national emergency was declared.) let's call the curve with r o = . also the herd immunity curve for usa, with an assumed infection rate of approximated %. after the emergency was declared and mitigation strategies implemented, a new r o = . was obtained (from an updated curve fit) for which we'll assume an infection rate of %. assuming a hospitalization rate of % for covid- , notice that the y-axis in figure (a) goes from zero to very large numbers. it is therefore a poor diagram for estimating the duration of an outbreak. to estimate how long an outbreak might last given a mitigation strategy, it is better to use a logarithmic scale as depicted in figure (b) which contains exactly the same information as figure all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint one of these strategies is implemented, the duration of an outbreak is far too long to halt an economy. available healthcare capacity is also abysmally under utilized and/or over utilized in all cases. the actual figures for the usa are staggering. there are roughly million staffed hospital beds [ ] , [ ] including icus in the country, of which about are available on a good day (prior to covid- .) if the available capacity can be raised to , for the epidemic, and the average stay of a hospitalized covid- inpatient is days, then on average only , beds are available per day for new covid- patients. to remain below this capacity threshold in terms of available staffed beds, the pandemic has to last longer than the minimum pandemic period, t p min . assuming an infection rate of % and a hospitalization rate of % then : where infection rate is simply the percentage of the total population who will be infected and the hospitalization rate is the percentage of all infected people who will be hospitalized. if the infection rate can be brought down to % with the same hospitalization rate of %, then the pandemic period becomes: t p min = . days = months days these are the shortest possible durations to remain below the capacity threshold under ideal circumdstances and could be plotted on graphs such as in figure as an ideal curve in the shape of a rectangle representing new cases. to reduce the minimum pandemic period, t p min , without excceeding capacity, either the infection rate, hospitalization rate, or the average stay per patient has to decrease, or the number of staffed beds have to increase. the important take aways from this is: • the national economy cannot endure being shut down even for the period under the ideal curve and • the period of time under the flattened curve is much longer than the length of time under the ideal curve. the intent with controling the curve using mapcm is to eliminate the long "tails" of underutilization that form part of the curve. this can be done by reshaping the curve so that the excess of inpatients expected during and around the peak can be treated beforehand or afterwards to fill up the underutilized portions above the curve and under the capacity threshold. this aim of the method is illustrated graphically in figure : before explaining how this can be accomplished, and since the pandemic is ongoing, it is necessary to offer a word of warning. caution: the method described in this paper can theoretically produce desireable results. however, the mapcm has never been tested in practice and has not yet been peer-reviewed. if the method is either misunderstood or implemented incorrectly, then it is possible to get worse than expected results. it is sensitive to timing, amplitudes, and other nuances. even small mistakes can have sizeable effects in theory and in practice. please do not attempt this method in practice unless your team is fully qualified, is fully aware of the consequences, and has fully explored the method and the underlying mechanisms at play. -wgo.kudu@gmail.com. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint a. oversimplified example ) assumptions: to illustrate the method in its simplest form, let's assume we have a homogenous population that can be dividided equally in n s isolated segments that are also homogenous. next let's asssume that there is only one possible reproductive number for the virus, r o . for example, it might be the rate at which herd immunity occurs. finally, we'll assume that there are only two possible states that can be present in each of the segments. in the first state the segment is in complete isolation and the virus has not been introduced into the segment population. in the second state, the virus spreads with r o . if isolation of a segment is terminated, that segment will be infected at r o up to an infection rate , i % . ) initial conditions: sufficient containment measures are put in place for the entire population to be in the uninfected, isolation state (or mitigated state). ) available control mechanism: as the government of the population, we are able to relax isolation measures for any segment(s) on any day of our choosing. the curves for the various segments add up to the reshaped curve. the curve for herd immunity can be replaced by a controllable, level curve that's been stretched out over a longer period of time. in fact, by choosing the times and segment sizes differently, the resulting curve's shape can be programmed to follow a wide variety of custom contours. this oversimplified example serves to illustrates the principle. however, it is idealistic and unrealistic, because segments cannot be isolated perfectly in practice. this section will explore examples that are less idealistic. keep in mind that these are paper studies for ilulstratio based on simple modeling of averages. in practice, pandemic outbreaks are stochastic, irregular, littered with exceptions (i.e. super spreading,) and generally more complex. in all the examples to follow, the method is applied to a logistic function model that was fitted to us data of confirmed cases and implementation that starts between march and march . a. moderate mitigation ) assumptions: in this example let's assume a homogenous population that can be divided in n s isolated segments of varying sizes. next let's asssume that there are exactly two possible reproductive numbers for the virus, r oh and r om , where r oh > r om . for example, r oh might be the reproductive rate at which herd immunity occurs, while r om is the reproduction number with certain mitigation measures in place. let's also assume that there are only two possible states to choose from and that only one of them can be present in each of the segments. in the initial state the virus infects the population of each segment with r om . once mitigation is relaxed in a specific segment, it switches to the herd state having r oh as the reproductive number. ) initial conditions: sufficient containment measures are put in place for the entire population to be in the mitigated state, with r o = r om . the reproductive number ratio is defined as: this ratio should increase proportional to the stringency of containment and isolation measures. infection rate is herein defined as percentage population infected. see definitions in the appendix. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . ) available control mechanism: as the governing body of the population, we are able to relax mitigation on any segment on any day. each segment will be infected at reproductive rate r om until mitigation for that segment is relaxed and it falls back to the higher reproductive number, r oh . ) infection rate: if left at the initial mitigated state, the virus can infect the population of a segment to a maximum of i %m of the particular segment's population. if mitigation measures are lifted so r oh takes effect, the virus can infect the segment's population to a maximum of i %h . in general, i %h > i %m . in the example it is assumed that i % = − ro . ) other rules and limitations: we are only able to switch each segment once or not at all. once at r oh , we'll also assume the rate cannot be switched back to r om . (this is merely to frame the example, and may not be true in practice.) ) example with proper mitigation: figure shows the results for two examples using moderate mitigation and r r = . %. with curve management implemented, the mitigation measures in each of the segments are relaxed at precise intervals. the curves for each segments then add up to the thick black curve. ) example with improper mitigation: figure shows that when i % changes from i %m to i %h in the segments as mitigations are relaxed, there is no overall improvement over pure mitigation at r om , but still an improvement over herd immunity. the area under the reshaped curve is identical to the area under the herd immunity curve if mitigation in all segments were relaxed at some point. these examples illustrate that, as long as i % ≤ i %h : the spikes in the curves are due to a derivative being taken of a logistic function with a discontinuity when ro changes. in practice this will be absent. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint ) herd immunity is the worst case scenario, ) even if the infection rate increases to that of herd immunity, the peak of the managed curve can be maintained well below the situation where mitigation is implemented for the duration of the outbreak, and ) attempting to implement curve management is better than mitigation without any curve management. (a) infection rate changes from i %s to i %m (b) infection rate changes from i %s to i %h in this example let's raise r r . again assume a homogenous population that can be divided in n s homogenous segments of varying sizes. next let's asssume that there are exactly three possible reproductive numbers for the virus, r oh , r om , and r os where r oh > r om > r os . for example, r oh might be the rate at which herd immunity occurs, r om the reproduction number with moderate mitigation measures in place, and r os when stringent mitigation measures are imposed. finally, we'll assume that there are only three possible states that each of the segments can be in. in the initial state the virus infects the population of each segment with r os . once mitigation is relaxed to moderate levels in a specific segment, it switches to the unmitigated state with r o = r h . ) initial conditions: sufficient containment measures are put in place for the entire population to be in the mitigated state, with r o = r os . ) available control mechanism: as the governing body of the population, we are able to relax mitigation on any segment on any day. each segment will be infected at rate r os until mitigation for that segment is relaxed and it falls back to the higher infection rate, r oh . ) infection rate: if left at the initial mitigated state, the virus can infect the population of a segment to a maximum of i %s of the particular segment's population. if mitigation measures are lifted so r oh takes effect, the virus will infect the segment's population to a maximum of i %h or i %m . in general, i %h > i %m > i %s . again it is assumed that i % = − ro . ) other rules and limitations: we are only able to switch each segment once or not at all. once at r oh , the rate cannot be switched back to r os . (again, this is merely to frame the example, and is not true in practice.) figure shows the results for examples in which the method is applied using these three reproductive numbers. in figure (a) the infection rate can go up to i %m and in figure (b) to i %h . the need for the more stringent mitigation measures were to buy more time to reduce the amplitude of the controlled curve, which cannot go beyond the curve with r os . figure shows a few different implementations. in figures (a) and (b) the timings for relaxing segment mitigation were chosen to make better use of the delay introduced by stringent mitigation. dividing the population into segments has now made it possible to reduce the amplitude of the controlled curve significantly, even when the infection rate reaches the high all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint value of % in figure (b). since the controlled curve ends well before the curve with the stringent mitigation, the amplitude can be reduced further by introducing more segments. in figures (c) the outbreak is started without delay and this is the soonest it can be started under the same criteria as figures (b) , but with controlled segments. in figure (d) the reproductive number is limited to r m upon relaxing the mitigation for segments. this is now even more realistic for practical implementation, and notice that the start of the outbreak is automatically delayed compared to the herd situation, since it cannot begin sooner than the moderate case allows. as before, the extent of the outbreak is also confined by r s , beyond which no control is possible. (a) infection rate changes from i %s to i %m (b) infection rate changes from i %s to i %h (c) infection rate changes from i %s to i %h (d) infection rate changes from i %s to i %m the active pandemic curve management method is so versatile that the curve can be programmed to custom fit it to specific predetermined criteria, such as changing needs. in figure (a) the curve is adapted to meet declining resources, for example to account for a decline in the health care work force due to more and more doctors and nurses falling ill to the virus. in figure (b) the curce is programmed for an increase, such as a field hospital that becomes operational. (a) custom curve for decreasing capacity. infection rate changes from i %s to i %h (b) custom curve for increasing capacity. infection rate changes from i %s to i %h fig. . examples of programming the curve to meet changing needs. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . figure (d) and figure (a) and (b) are the ones that show the most promise for practical implementation. the numbers used are unimportant and the models can be replaced by any appropriate substitute, but these examples show that moderate and stringent mitigation can be applied in a smart way to program the curve to desired needs. mixed modes are also possible within the same strategy. in other words, it's not necessary to limit the reproductive numbers in any way. they can be applied in any mixed configuration to segments. to the author's best knowledge this methodology has never been proposed, let alone been attempted, for managing the outbreak of an epidemic. it uses a quasi-open-loop control method borrowed from electrical engineering to shape the outbreak curves. similar pulse-shaping is performed for electromagnetic launcher technology shown in figure (a) in the author's laboratory during every firing event, except that it all happens within one-thousandth of a second instead of over months. there are some similarities between controlling a pandemic curve and controlling the railgun. both are complex systems and each produces an unwanted curve that needs to be shaped into something else. applying the method to a pandemic makes it possible to get ahead of the curve by controlling the outbreak, instead of staying behind the curve and letting this curve control a country. attempts were made to share this method with the white house coronavirus task force since the beginning of march , and was finally transmitted via the office of a congressman. it was shared with a few governors by fax. no response was received. the author is seeking funding and potential partners to expand capabillities in this area while there is time to respond to the virus. the method can be useful to many countries that want to get ahead of the curve, especially those with economies that are too fragile to go into full-on lock-down like the usa is doing. in the usa, the method could be implemented at the national level or at the state level. since every locality has a unique character with its own unique challenges, the viability of this reshaping method needs to be tested using their own models and their own mitigation measures before implementing it to address their specific needs. the mapcm method has to be implemented before the virus has infected significant portions of a population. since this method is not untuitive, it may seem like time travel to people not familiar with control methods when applying it to disease. this is not the case. it only seems so because it involves people over days, weeks, and months. another possible objection is that people are being infected deliberately. this isn't the case either. infections that would have all happened in a short period are spread out over a long period. but what if the death rate is very high? the death rate should not make any difference, because the mapcm doesn't sacrifice lives, but saves lives. figure (b) plots the mortality rate among all resolved cases for the usa up until march . the death rate for usa on this date is %. however, it should be noted that using the number of recoveries and number of deaths on a specific day in the equation: fatality rate among resolved cases = deaths deaths + recoveries ( ) is not comparing apples to apples, because the average occupancies differ between patients who expire and those who are discharged from hospitals. and hospital policies before discharging a patient may also differ from country to country and hospital to hospital. in figure (b) the fatality rates among resolved cases are also plotted for occupancies that are offset by all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint + and - days, showing that only a few days can make a big difference in calculating the death rate. according to [ ] the difference is only days. using full mitigation, the lives of only some people (who are being considered essential, such as doctors and nurses, food distribution, delivery, etc.) are being risked in the war against a pandemic, while the rest of the population are forced to isolate. during a war the security of the nation is everyone's responsibility. rather than isolating people by force, the rest of the population can be educated to protect themselves the way doctors and nurses do when dealing with infected patients, and allowed back in the activated economy in a controlled manner to do their part. the level of self-isolation can then be left up to each individual to choose for themselves. masks can be worn in grocery stores and public places. those who are known to be at risk, such as the aged and those people with underlying conditions should obviously be protected by keeping them isolated as much as possible. the strategy of full mitigation in the usa is a great starting point for addressing a pandemic. however, prolonging it will put the entire nation through a lot of misery with many businesses closing and millions of people losing their jobs. it is totally pointless to place a nations economy in a comatose state for several months when it can be resolved in a controlled manner. • the method allows spreading out the cases evenly without asphyxiating the economy or sacrificing lives. • the success of the method can be improved upon the more accurate the model being used is, because control decisions are made based on predictions. • the method can be implemented even without a good model. • the accuracies of all appropriate models can be improved by eliminating unknown variables via a scientific process of testing that has been lacking thusfar. • the method can be improved by a feedback loop using test data. feedback control can handle large time delays. the better test data is in accuracy, scale, and timeliness, the more responsive this method can be. • the case data for the examples are based on us national averages. it would be better to implement the method at the state level, than at the national level. • partitioning is not limited to geography, but can be implemented based on demographics, and any number of methods. • the curve is programmable • the outbreak timing becomes programmable. it can be started earlier or later than suggested by the herd or mitigated curves. • the curve can be adjusted to accommodate changes in healthcare resources, for example a field hospital becoming operational. • if those that are at risk can be isolated, such as the elderly and those with underlying issues, while the rest of the population is gradually loosened back to normal life, then the death rate can be reduced furtner. • small populations are infected faster than large populations. instead of applying full mitigation to flatten the coronavirus curve and asphyxiating the economy as a national side effect, there is a way to actively shape that coronavirus curve using a new technique. for the reshaping method to be successful, there are a few objectives that need to be accomplished. basically, the duration of the outbreak must be shortened and stopped in its tracks, the curve need to remain under the available healthcare capacity threshold while allowing breathing room for the economy, all without putting more lives at risk. the new technique, coined mapcm for managing a pandemic using a quasi-open-loop control method to shape the outbreak curve related to the spread of an infectious disease into a population has been introduced by means of examples. this method makes it possible, for example, to impose mitigation amid a pandemic crisis to keep the hospitalizations within available healthcare capacity thresholds while keeping the economy moving without sacrificing lives. it was shown how the amplitude and duration of a controlled curve can be traded off against one another. better results can be achieved using the method than imposing mitigation by itself. this method is promising if implemented early enough in outbreak cycle. it was also demonstrated that the method can be used to program the outbreak curve to custom fit changing needs. the rules and mechanical logistics for controlling the curve of an actual country or locality depend on the unique identity and character of the locality. the rules and mechanisms for implementing mitigation strategies in combination with mapcm will be treated elsewhere. a. definitions ) time: so as not to be confused by the metric system, time is not measured in seconds, but in days, for the simple reason that case data are typically collected and recorded on a daily basis. ) reproductive number: in this paper the reproductive number, r o refers to the average number of people being infected per person in a day at the start of the outbreak as defined in equation ( ) . this definition has the advantage that it can be deduced directly from the data collected. all rights reserved. no reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medrxiv a license to display the preprint in perpetuity. the copyright holder for this preprint this version posted april , . . https://doi.org/ . / . . . doi: medrxiv preprint ) infection rate: the infection rate, i % is the percentage of a population that will be infected by the end of the outbreak cycle. ) hospitalization rate: the percentage of infected people who become hospitalized. ) fatality rate: the percentage of infected people who expire. also called the mortality rate or death rate. this part of the appendix contains the hybrid logistic model that was used to generate the plots in the examples. as noted before, the model and the numbers used are unimportant. this paper presents a method and not a model. the mapcm is compatible with any other appropriate model. in the plots in figure it is assumed the incubation period is days, the infection rate is %, and the fatality rate is %. these numbers are guesstimates, but can be replaced by reliable data. there are conflicting reports about fatality rates. while low tests number in combination with deaths as a percentage of confirmed cases result in a very low death percentage, it is not the case for percentage deaths among resolved cases, as discussed on page the fatality rate among resolved cases is significantly higher. the number of infected include symptomatic and asymptomatic infections in the usa. test efficiency is the percentage of people who became symptomatic after the average incubation period who've tested positive for covid- . since we don't know what the test efficiency is, lines were plotted for %, %, %, and %. these are averages for the entire country. the plot uses r o = . , a reproductive number for the us after the disease entered community spread mode and before mitigation strategies were implemented. confirmed cases surged as more and more testing was being performed in march. the earlier parts of the lines can be ignored. the response changed as of / / when the mitigation measures initiated by the white house and the states started to manifest in the cases being reported. as a result all the curves have sharp inflections as they take on a lower reproductive number r o = . at some point after the measures were announced. the death rate will not follow the curve yet, because it will be delayed by some average intensive care period. where the death rate will settle also remains an open question until reliable data is acquired. american hospital capacity and projected need for covid- patient care u.s. icu resource availability for covid- forecasting covid- impact on hospital bed-days, icu-days, ventilator-days and deaths by us state in the next months key: cord- -maep fie authors: huynh, toan luu duc; nasir, muhammad ali; nguyen, duc khuong title: spillovers and connectedness in foreign exchange markets: the role of trade policy uncertainty date: - - journal: q rev econ finance doi: . /j.qref. . . sha: doc_id: cord_uid: maep fie this paper analyses the directional spillover effects and connectedness for both return and volatility of nine us dollar exchange rates of globally most traded currencies under the influence of trade policy uncertainty. we find two interesting results over the study period ranging from december to july . first, there exists asymmetric spillovers and connectedness among the considered exchange rates when trade policy uncertainty is present. second, the volatility spillover is stronger than the return connectedness between exchange rate and trade policy uncertainty. these findings are robust to the presence of economic policy uncertainty effects. concomitantly, the trade policy uncertainty patterns are also found to be useful for predicting currency market dynamics. our findings contribute to the debate on the impact of trade policy uncertainty on the global economy and financial sector. in the wake of the recent trade wars between the united states and china as well as between the united states and its neighbours and allies including canada, mexico, and european union, the global economy has been experiencing high levels of uncertainty in terms of economic policies, trade negotiations, proposals, and trade deals. the obvious reason leading to the trade tension and trade war was the large us trade deficit, mainly with china, germany and japan, where there have been accusations of competitive devaluation of the exchange rate and unfair trade practices j o u r n a l p r e -p r o o f (nasir and jackson, ) . the united states has also withdrawn from the trans-pacific partnership (tpp), imposed tariffs and renegotiated the north atlantic free trade agreement (nafta) within the united states-mexico-canada agreement (usmca or also known as nafta . ) (brox and fader, ) . according to baker et al ( a) , actions and events such as the us withdrawal from the tpp, the brexit, and the us-china trade tensions raised import tariffs and escalation in trade disputes, which leads to a significant increase in the trade policy uncertainty (tpu) . previous studies have shown the important implications of uncertainty for the financial sector and the economy as a whole, following the seminal work of knight ( ) which pioneered the scholarly endeavours to understand the causes and the consequences of uncertainty. it is now common that high levels of economic uncertainty can have significant impacts on, among others, the probability of recessions, bank loans' pricing, cost of capital, corporate cash policy, corporate innovation, and currency exchange activities (e.g., karnizova and li, ; berg and mark, ; ashraf and shen, ; li, ; xu, ) . economic agents and policymakers thus face a number of various economic challenges as economic uncertainty makes it difficult to forecast the future economic and financial outlook as well as to carry out effective forward-looking macroeconomics policies (nasir, ) . the study of bloom ( ) examines "the impact of uncertainty shocks" on the us economy using firm-level data and shows that rising uncertainty can push firms to halt their investment and recruitment, and further have a negative impact on productivity in the short-term. however, the productivity, employment, and output bounce back in the medium term as the uncertainty fades. a more recent study by basu and bundick ( ) documents the negative effects of uncertainty on output, consumption, investment, and hours worked. they further argue that uncertainty can cause price instability and hence have implications for the monetary policy. nonetheless, it can also make the recessions worst, particularly in the zero lower bound regimes. an important aspect of uncertainty is its implications for the effectiveness of the economic policy. bernanke ( ) show that fiscal policy uncertainty has been acting as a headwind for the recovery of the us economy after the global financial crisis [ ] [ ] . insights into the negative impact of policy uncertainty were also provided in fernández-villaverde et al ( ) . in their analysis addressing the impact of fiscal policy uncertainty on the us economy through the use of j o u r n a l p r e -p r o o f a var and new keynesian models, fernández-villaverde et al ( ) report that the unexpected changes in the fiscal volatility shocks can have sizable adverse effects on economic activity. regarding the trade tensions and resulting trade policy uncertainty, the recent empirical evidence suggests adverse implications for various aspects of the global economy and financial sector such as tariffs, exports, market access, investments, economic activity, employment, and stock markets (osnago et al, ; crowly et al., ; osnago et al., ; baker et al., , caldara et al., . specifically, the us-china trade war, as declared by the us president donald trump, is found to not only harm the us equity market (burggraf et al., ) but also detrimental for the global stock markets (huynh and burggraf, ; thanh et al., ) . our paper contributes to the existing literature on economic and trade uncertainty by examining the impact of the tpu on exchange rate markets. this investigation is crucial because trade uncertainty arising from international trade disputes is supposed to have a direct bearing on exchange rates dynamics. more precisely, we empirically assess the directional (return and volatility) spillover effects and connectedness among nine globally most-traded currencies against us dollar exchange rates under the tpu context. in terms of measurement of tpu, we follow the tpu index constructed by baker et al. ( a) , whose effectiveness relies on the frequency of joint occurrences of trade policy and uncertainty terms across major newspapers. accordingly, trade-policy news and anxieties are a potential source of uncertainty which may be transmitted to exchange rate volatility when the parties are embroiled in trade conflicts with major trading partners. the nine globally most-traded currencies against us dollar employed in this study are from the countries which are among the main trading partners of the united states. the statistics as of december from the us census bureau show, for example, that canada, japan, the united kingdom account respectively for . %, . %, . % of the us total trade in goods, while the trade in goods between the united states and the european union ( out of member countries use the euro currency) reached us$ . billion or . % of the us total trade in goods. to the extent that the tpu has political dimensions and expectations around the trade policy stance, our work draws on the theoretical framework put forward by engel and west ( ) as well as beckmann and czudaj ( ) , which explains the exchange rate volatility through expectations channels (conrad and lamla, ) . using the generalized var, directional spillovers and connectedness measures developed respectively by diebold and yilmaz ( ) , and diebold and yılmaz ( ) , our study leads to several important findings over the period from december to july . firstly, the degree of directional volatility and return spillovers as well as the associated dynamic connectedness are not alike across the considered exchange rates under the influence of trade policy uncertainty. secondly, the volatility connectedness between exchange rates and trade policy uncertainty is found to be stronger than the return connectedness. finally, the role of the tpu regarding return and volatility transmissions in exchange rate markets remain robust when the so-called economic policy uncertainty is introduced into the model. these findings thus imply that trade policy uncertainty patterns are important information for economic agents and useful in predicting currency market dynamics. the remainder of the paper proceeds as follows. section briefly reviews the existing literature. section introduces our methodological framework and data used. section reports and discusses the empirical results. section provides some concluding remarks and policy implications. since the global financial crisis - , a number of studies have focused on the measurement of uncertainty in its various forms, including the tpu. in their seminal paper on economic policy uncertainty, its measurement and impact, baker et al. ( ) reported that the policy uncertainty leads to increased volatility in the stock markets and adverse impact on investment. furthermore, it also causes an increase in unemployment and a reduction in the output in the united states as well as in other major economies. a later study by baker et al. ( a) empirically establishes that tariff hikes, tariff threats, and tariff retaliation are the crucial sources of anxiety and the tpu can have an adverse impact on the us economy. moreover, the increase in tpu contributes to exacerbating the equity market volatility proxied by the implied volatility index (vix). it is worth noting that one of the pivotal points regarding the construction of the tpu index is the selection of trade policy related news in american newspapers instead of the general perspectives in the whole economy. the tpu thus corresponds to a specific category of the overall economic policy uncertainty and reflects the uncertainty and intensity of trade policy discussions. osnago et al. ( ) investigate the margins-of-trade effects of tpu for a sample of exporting countries, where the trade policy uncertainty is measured as "the gap between binding tariff commitments under trade agreements and applied tariffs". they report the adverse effects of tpu on exports with the negative impact of tpu being higher in the countries whose institutional quality is low. their obtained results suggest that the negative impact of tpu ranges from . to . % of tariffs. in a more recent study, osnago et al. ( ) reach similar conclusions in that tpu constitutes an important obstacle to exports for exporters and that its effects are heterogeneous across exporters. the probability of exporting and trade volume would increase by % and % respectively if all tariff gaps are eliminated. on the other hand, there is an ample evidence to suggest that the economic fundamentals drive the exchange rate dynamics in the long term, although the policy announcements are considered to possess the short to long-term effects (e.g., taylor et al., ; sarno and taylor, ) . a study by nasir and morgan ( ) documents that the uncertainty preceding the brexit had caused the gbp to depreciate significantly. they associate this sharp depreciation with increased uncertainty about the uk's trade policy and future trading relationships with the european union. based on this line of reasoning, it implies that the uncertainty in general and the tpu in particularly may have implications for the exchange rate markets. however, the existing evidence does not provide much insights into the role of tpu in foreign exchange rate markets. to address this caveat in the existing literature, this paper analyses the implications of tpu for the exchange rate markets. we formally test the hypothesis that the increases in tpu will result in the rising spillover effects in the exchange rate markets. our focus is on both return and volatility spillover effects as well as the robustness check of the tpu impacts when the economic policy uncertainty is also considered. in order to investigate the spillover effects and connectedness for both returns and volatility of nine us dollar exchange rates, we follow diebold and yilmaz ( ) , and diebold and yılmaz ( ) to specify a generalized var model where exchange rate returns and volatility are alternatively used as dependent variables along with the tpu returns and volatility. this empirical approach allows us to generate the total spillover index based on the h-step ahead generalized forecast error variance decomposition (gfevd) and to assess the degree of connectedness based on the directional spillover index (baruník and kočenda, ) because the approach of baruník and kočenda ( ) accounts for the spectral representation of variance decompositions for highfrequency data. therefore, we also consider the aforementioned approach to estimate for the spillover effects and connectedness in this study. before the generalized var model can be set up, we need to calculate the average monthly return and realised volatilities. our realised variances (rv) are calculated using the approach proposed by andersen and bollerslev ( ) , which can be specified as follows: ( ) where = − − with being defined as a continuous-time stochastic process of logprices at k. this stochastic process with pure jump component is further modelled as in eq. ( ): where means a locally bounded predictable drift process, and denotes positive volatility process. indicates a jump part and all factors have common filtration. for the estimation of asymmetric realised variance, we drew on the approach proposed by engle ( ). since our dataset contains daily time series, we transformed daily data into monthly data in order to match with the monthly tpu index. for this purpose, monthly average returns for exchange rates and tpu index are calculated from the daily returns at time k ( ): despite the availability of monthly exchange rate data, we choose to employ daily data to construct monthly exchange rate returns from daily observations because this method allows us to capture a rich and dynamic patterns of both exchange rate return and volatility. as it has been shown in previous studies (zhou, ; gatheral et al., ) , using the first and last monthly observation of exchange rate to compute the returns and volatility would lose a number of stylized facts in between observations. given the availability of monthly average returns and realized variances, we employ the generalized var and spillover index of diebold and yilmaz ( ) , and diebold and yılmaz ( ) to estimate the directional return and volatility spillovers among exchange rates in the presence of tpu effects as well as between tpu and us exchange rates. this approach is advantageous in that it is invariant to the ordering of the variables. it also allows for the calculation of both the direction and strength of spillovers over time and among different variables. we build a var(p) j o u r n a l p r e -p r o o f process for the vector of realised volatilities (average returns) of both tpu index and exchange rates, ex t = (ex t , … , ex nt ) ′ , such as: the moving average representation of residual ε t in var(p) has the following form: where coefficients are in the matrix of Ψ i . eq. ( ) briefly summarizes the total spillovers index by using h-step-ahead generalized forecast error variance decomposition matrix, having the following elements for h = , … more precisely, Ψ h is the matrix having the moving average coefficients, forecasted at time t while Σ ε denotes the variance matrix for the error vector ε . is the k th diagonal element of Σ ε . in addition, e j and e k are selection errors with one as the j th and k th element and zeros otherwise. we follow the approach of baruník and kočenda ( ) to measure directional spillovers from exchange rate j to exchange rate k as follows: the receiving effects are calculated when adding all numbers in rows j except the terms on a diagonal which correspond to own impacts. the sending effects are estimated by the sum of numbers in the column, excluding the numbers on the diagonal terms. figure shows the dynamics of tpu and the selected exchange rates, consisting of gbp and eur, over the study period. this figure can be exemplified how the exchange rate returns could co-move the dynamics of trade policy uncertainty. table summarizes the data characteristics along with stationarity and structural break testing. table shows evidence of asymmetries and fat tails in the probability distributions of exchange rate returns, given the non-zero values of skewness coefficients and kurtosis coefficients superior to in all cases. we also perform the jarque-bera test and find that all series depart from normality. it means that all variables are non-normal distribution. four out of nine exchange rates under consideration exhibit the negative average return over the study period (usd/chf, usd/eur, usd/jpy, and usd/nzd). furthermore, since we use the var model to derive return and volatility spillovers, it is necessary to make sure that our variables are stationary in order to avoid estimation biases. following chevallier et al. ( ) , we use the zivot-andrews test to examine the null hypothesis that our variables contain a unit root while assuming a potential exogenous structural change. the obtained results indicate that the null hypothesis is rejected for all variables at the % level, which suggest that we can proceed with further quantitative estimations. figure displays the heat map correlation with regard to returns and realised volatility. we observe that the correlation of tpu with exchange rates is relatively higher in return than in volatility among our variables. noticeably, the exchange rate of gbp has a high volatility correlation with the remaining variables, while the exchange rate of chf tends to be immune to the volatility linear dependence. the return correlation is quite modest, except for the pair of chf-eur, nzd-aud, and nok-sek. these currencies have a strong linear dependence. this finding can intuitively be understood in the light of the close economic and geographical association between these economies and hence their currencies. table summarises the results on connectedness among the pairs of exchange rates and trade policy uncertainty. at first sight, we see that the return spillover effect from tpu to exchange these results are available upon request. j o u r n a l p r e -p r o o f rate returns is considerably marginal, as it does not exceed % in all cases and its total given spillovers only sum up to . %. the top three currencies that received the most spillover effects from tpu include the norwegian krone, the swiss franc, and the new zealand dollar. this could be explained by the fact that norway and new zealand are significantly exposed to trade activities with both the united states and china, while trade policy uncertainty can incite investors to trade more the swiss franc given its safe haven property. on the other way around, the transmission of shocks affecting exchange rate returns to tpu is greater with a total spillover effect of %. the most important givers of spillovers among the exchange rates are the swiss franc ( . %), the japanese yen ( . %), and the euro ( . %). the return spillovers among exchange rates are richer than between them and the tpu, even though their own variance shares are still high and range from . % (sek) to . % (chf). the sek, jpy, cad, and nzd currencies are the most vulnerable to return shocks of other exchange rates. in terms of net spillover effects, the tpu stands as the fifth most important receiver of return spillovers (- . %), behind the exchange rates of sek (- . %), jpy (- . %), cad (- . %), and nzd (- . %). by contrast, the exchange rates of gbp, chf and nok are the return spillover givers with a net transmission of . %, . %, and . , respectively, suggesting that they can provide some valuable indications about the changes in other exchange rates and trade uncertainty. table shows the static volatility spillover effects among the exchange rates and trade policy uncertainty. we can easily see an increase in the level of their volatility transmissions as compared to the return transmissions in table since the own variance share of tpu is now reduced to . % ( % in the return spillovers) and it gives a total volatility spillover of . % to exchange rates (only . % in the case of return spillovers). the highest volatility spillover from tpu to exchange rates is observed for the case of the canadian dollar ( . %), followed by the new zealand dollar ( . %) and the norwegian krone ( . %). the total contributions of exchange rates to the forecast error variance of the tpu's volatility also increase and attain . %, compared with % in the case of return spillovers. the most important giver of volatility spillovers to the tpu is the exchange rate of the japanese yen ( . %), followed by the new zealand dollar ( . %) and the australian dollar ( . %). it is worth noting that the changes in the volatility of the chf exchange rate do not exert the same importance as in the return spillover to the j o u r n a l p r e -p r o o f tpu (only . %). surprisingly, the euro has very little volatility spillover effect with the tpu throughout the period from to , despite the fact that the united states is the largest trading partner for eu exports of goods and the second-largest partner for eu imports of goods. however, the foremost finding of table is that the tpu is a net transmitter of volatility spillovers ( . %), suggesting that a higher degree of trade policy uncertainty could raise instabilities in the foreign exchange markets. among the exchange rates, the gbp, aud, and jpy currencies are the net sender of volatility transmission with . %, . %, and . %, respectively, whereas the remaining exchange rates are net receivers of external volatility shocks. our work thus does not confirm the previous literature regarding the prominent role of the canadian dollar in volatility transmission (wen and wang, ) . this currency's impact is also limited in terms of return spillover effects. the high sensitivity of the nok and sek currencies to external volatility shocks could potentially be related to their export-driven and resources-based economy structures which depend on international prices of commodities and economic outlooks. namely the cad, chf, and nok, have the asymmetric return connectedness, while the remaining currencies exhibit one side shock transmission only (either sender or receiver). more precisely, the gbp is the most important transmitter with the rolling spillover effects in return ranging from % to %. another important finding is that the eur acts as a return shock recipient, but it plays a more crucial role in volatility transmission as a sender of volatility shocks ( figure ). european debt crisis. by contrast, the aud and gbp are mainly transmitters of volatility shocks, except for some short periods. the evidence regarding the tpu's volatility transmission thus implies that it can be a useful tool to predict exchange rate volatility. this section examines the relevance of tpu in explaining the dynamics of exchange rate returns and volatility when the soc-called global economic policy uncertainty (gepu) proposed by baker et al. ( ) is introduced into the estimation models. to the extent that the data for the gepu only started since , we have to shorten our sample period and conduct our robustness analysis from january to july . due to its global coverage and economic-wide uncertainty nature, it is expected that the gepu has a strong correlation with the tpu and drives shocks to the tpu. however, to our great surprise, the correlation between the gepu and the tpu is only moderate ( . ), despite significant. this preliminary evidence suggests that the tpu brings incremental contributions to the explanation of exchange rate dynamics, even in the presence of the gepu. table shows the volatility spillover effects of the same system when the gepu is added. what is important to note is the increase in the average spillover effects that goes from . % (table ) to . % (table ). this result indicates the benefit of having the gepu in the model as it helps improve the interactions and explanations of exchange rate volatility. as expected, the gepu transmits more volatility shocks to the tpu ( . %) than the other way around ( . %). this can be explained by the fact that the economic policy uncertainty, as a factor encompassing a broad economic spectrum, causes an unstable business environment which leads to more uncertainty in trading policies and activities. however, the tpu remain superior to the gepu in driving exchange rate volatility with a total transmission of . %, compared to . % by the gepu. it is also interesting to note that both uncertainty indexes receive volatility shocks from exchange rates ( . % for the gepu vs. . % for the tpu), with the highest pressures from aud and jpy currencies. in addition, as in table , the currencies of high oil-dependent nations (sek, nok, can, eur, and gbp) are the most affected by shocks to other variables in the system. finally, the impact of the tpu on exchange rate volatility is very similar to the finding of table when the gepu is not included. at the same time, the aud, jpy and nzd are the currencies exhibiting the largest contagious effects to the tpu. taken together, the tpu stands as an important factor for explaining the dynamics of exchange rate volatility, whether the gepu is considered or not. in sum, the empirical evidence reported here points to the fact that the exchange rate returns and volatilities are associated with trade policy uncertainties, captured by the news-based estimation approach. it is also shown that not only the tpu strengthens volatility spillovers of exchange rates but unexpected shocks to exchange rates also account for . % of changes in tpu (table ), leading to their negative efects on international trade and economic growth in case of high exchange rate volatility. therefore, stabilizing exchange rates would be a crucial challenge for policymakers and central bankers in times of rising trade policy uncertainty. the contemporary global trade imbalances have caused trade tensions and resulted in trade wars. the latter has, in turn, caused a significant amount of economic and trade policy uncertainty. the current literature in financial economics is, however, very limited to the understanding of trade policy uncertainty effects. concerns over international trade uncertainties thus intensified the policy debate and provided the rationale to research on their consequences for the global economy and financial sector including exchange rate markets. contextualising on the importance and underexplored of trade policy uncertainty, this study provides the first empirical investigation of the static and dynamic interactions between the us trade policy uncertainty and the us dollar exchange rates of the ten most globally traded currencies. our analysis of volatility and return spillovers shows evidence of significant, asymmetric, and heterogeneous spillover effects between tpu and exchange rates, and among exchange rates themselves. similar results are obtained when we consider the return and volatility connectedness based on a rolling approach. moreover, we find that volatility connectedness between exchange rate and trade policy uncertainty is higher than their return connectedness. finally, our findings regarding the role of tpu in explaining the exchange rate returns and volatility remain intact when the global economic policy uncertainty is introduced. while the existing literature focuses on equity markets (antonakakis et al., ) , fixed-income market (wisniewski and lambe, j o u r n a l p r e -p r o o f ), and the precious metals market (huynh, ) , our findings confirm the role of trade policy uncertainty as a driving force of the dynamics of exchange rate markets. our results suggest that policymakers, trading partners, and investors should pay attention to the changes in tpu and their effects on exchange rate movements due to bilateral spillover effects. subject to high exchange rate volatility under important trade policy uncertainty, global investors may attempt to design internationally diversified currency portfolios that protect them from systematic risk in foreign exchange markets by considering empirical sensitivities of us dollar exchange rates to policy uncertainty. furthermore, there is also evidence that the monetary policy uncertainty is the main driver of economic policy uncertainty, followed by the fiscal policy, currency and finally trade policy uncertainty gupta et al. ) . therefore, at the macroeconomic level, the effectiveness of monetary policy and monetary policy communication might mitigate the severity of trade policy uncertainty. future research can extend our study by considering alternative trade policy uncertainty such as the one developed by caldara et al. ( ) based on firm-level data and by assessing the impact of tpu on other asset markets such as equity and commodities. it would be also interesting to examine how uncertainties related to the ongoing covid- pandemic which has disrupted the global trade follows alter the results. the authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. the total observation is . zivot-andrews represents the minimum t-statistic. the identified break dates are presented in the 'year month' format. in addition, the critical values for %, %, and % significance level are - . , - . , and - . , respectively. ***, **, and * denotes rejection of null hypotheses at the %, %, and % levels of significance. '_v' denotes the realised volatility for each exchange rate pair. these exchange rates are indirect quotations of nine currencies against the usd from wm/reuters. the snapshots are taken from the reuters system around pm and median rates are then selected for each currency from to construct this exchange. the mean values are in the percentage form, while the proxy of tpu is used as the natural logarithm to take into account for the uncertainty changes in unit instead of percentage changes. more noticeably, our tpu variable is stationary at % significance level, which means that it is suitable for further statistical analysis. j o u r n a l p r e -p r o o f bitmex bitcoin derivatives: price discovery, informational efficiency, and hedging effectiveness answering the skeptics: yes, standard volatility models do provide accurate forecasts dynamic co-movements of stock market returns, implied volatility and policy uncertainty measuring economic policy uncertainty. the quarterly journal of economics policy news and stock market volatility (no. w ) the extraordinary rise in trade policy uncertainty total, asymmetric and frequency connectedness between oil and forex markets uncertainty shocks in a model of effective demand exchange rate expectations and economic policy uncertainty the dynamic effect of macroeconomic news on the euro/us dollar exchange rate remarks before the committee on financial services, us house of representatives the impact of uncertainty shocks electronic commerce, exchange rate volatility and changes in trade patterns: canada under nafta political news and stock prices: evidence from trump's trade war the economic effects of trade policy uncertainty market integration and financial linkages among stock markets in pacific basin countries the high-frequency response of the eur-usd exchange rate to ecb communication tariff scares: trade policy uncertainty and foreign market entry by chinese firms better to give than to receive: predictive directional measurement of volatility spillovers on the network topology of variance decompositions: measuring the connectedness of financial firms exchange rates and fundamentals volatility and time series econometrics: essays in honor of robert engle fiscal volatility shocks and economic activity volatility is rough. quantitative finance common business cycles and volatilities in us states and msas: the role of economic uncertainty if worst comes to worst: co-movement of global stock markets in the us-china trade war the effect of uncertainty on the precious metals market: new insights from transfer entropy and neural network var risk, uncertainty, and profit exploring all var orderings for calculating spillovers? yes analyzing time-varying volatility spillovers between the crude oil markets using a new method dynamic frequency connectedness between oil and natural gas volatilities pre-brexit: the eu referendum as an illustration of the effects of uncertainty on the sterling exchange rate an inquiry into exchange rate misalignments as a cause of major global trade imbalances trade policy uncertainty as barrier to trade the heterogeneous effects of trade policy uncertainty: how much do trade commitments boost trade? the economics of exchange rates brexit and the macroeconomic impact of trade policy uncertainty nonlinear mean-reversion in real exchange rates: toward a solution to the purchasing power parity puzzles asymmetric effects of us monetary policy on the us bilateral trade deficit with china: a markov switching ardl model approach can economic policy uncertainty predict exchange rate volatility? new evidence from the garch-midas model high-frequency data and volatility in foreign-exchange rates volatility connectedness in global foreign exchange markets how has trade policy uncertainty affected the world economy does economic policy uncertainty drive cds spreads? international review of financial analysis directional volatility spillovers (semn) which correspond to the percentage share of error variance in exchange rate (rows) contributed by shocks to exchange rate (columns) including the existence of tpu. total received spillover for exchange rate is given by its row sums results of the volatility spillover effects performed with the generalized fevd (gfevd). directional volatility spillovers (semn) which correspond to the percentage share of error variance in exchange rate (rows) contributed by shocks to exchange rate (columns) including the existence of trade policy uncertainty and economic policy uncertainty. total received spillover for exchange rate is given by its row sums reported in the columns added to the right of the table, both including ∑ = ) = and excluding ←• own variance share. key: cord- - lmudxrh authors: nan title: antimikrobielle und antiinfektiöse maßnahmen date: - - journal: krankenhaus- und praxishygiene doi: . /b - - - - . - sha: doc_id: cord_uid: lmudxrh nan • die transiente hautflora besteht aus nur zeitweise auf der haut vorkommenden bakterien, pilzen oder viren einschließlich nosokomialer infektionserreger. bakterien und hefepilze überleben meist eine stunde oder länger. bei viren reicht die dauer der persistenz von min bis zu mehreren stunden (› tab. . ). • die infektionsflora beinhaltet das vorkommen von ätiologisch an aktuellen infektionen der hand (wie abszessen, panaritium, paronychie, infiziertem ekzem) beteiligten erreger. Übertragung nosokomialer infektionen durch hände: verschiedene ni werden über die hände von mitarbeitern übertragen, vor allem ssi, septikämien und pneumonien (kampf, löffler und gastmeier ) . gleiches gilt für die ausbreitung von mre. durch händedesinfektion wird daher die anzahl kolonisierter bzw. infizierter patienten reduziert (brown et al. ; gagné, bédard und maziade ; girou et al. ; gordin et al. ; johnson et al. ; kaier et al. ; simor et al. ; trick et al. ) . ebenso ist die effizienz bei der unterbrechung von ausbrüchen nachgewiesen (armbrust et al. ; cheng et al. ; fung und cairncross ; simor et al. ). indikationen: schutzhandschuhe dienen sowohl dem eigenschutz als auch der unterbrechung von infektionsketten (johnson et al. ; tenorio et al. ). sie müssen immer dann angelegt werden, wenn der kontakt mit erregern vorhersehbar oder wahrscheinlich bzw. wenn eine massive verunreinigung mit körperausscheidungen, sekreten und exkreten möglich ist (trba , ) . beispiele sind blutentnahmen, die pflege inkontinenter patienten, waschen von mrsa-patienten, umgang mit beatmungsschläuchen, entleerung von wasserfallen, endotracheales absaugen, tracheostomapflege, entsorgung von sekreten, exkreten und erbrochenem sowie die entfernung von drainagen, verbänden oder kontaminierten materialien. da die perforationsrate mit zunehmender tragedauer im pflegeprozess steigt, sollte sie auf etwa min beschränkt werden. dabei sind nitrilhandschuhe den latexhandschuhen überlegen. da die perforationsrate nach patientenwaschung und verbandswechsel signifikant erhöht war, sollte hiernach in jedem fall ein handschuhwechsel durchgeführt werden (hübner et al. ) . der einsatz textiler aufbereitbarer unterziehhandschuhe hat durch absorption der feuchtigkeit einen günstigen einfluss auf den hautzustand und wurde für den routineeinsatz in der patientenpflege überwiegend bejaht (hübner et al ) . nach beendigung der tätigkeit, ggf. auch zwischen der verrichtung verschiedener tätigkeiten an einem patienten, sind die handschuhe im allgemeinen abzulegen. anschließend ist eine händedesinfektion durchzuführen, da handschuhe durch unbemerkte perforation oder kontamination der hände beim fehlerhaften ausziehen keinen sicheren schutz vor einer kontamination der hände gewähren (doebbeling et al. ; korniewicz et al. ; tenorio et al. ). handschuhwechsel erforderlich ist, aber erfahrungsgemäß häufig nicht durchgeführt wird, oder wenn eine notfallsituation zwischen dem kontakt von kontaminierten bedienelementen und dem patienten keinen handschuhwechsel zulässt. dabei sind drei voraussetzungen zu berücksichtigen (kramer et al. b ): • der handschuh muss nachweislich desinfizierbar sein (häufigkeit, materialverträglichkeit, handschuhfabrikat, desinfektionsmittel müssen bekannt sein). • der handschuh weist keine bemerkten perforationen auf und ist nicht mit blut, sekreten oder exkreten kontaminiert. • es besteht keine erhöhte wahrscheinlichkeit einer kontamination mit chemoresistenten viren oder mre. schutzhandschuhe sind wegen des risikos der hautschädigung und erhöhter perforationsgefahr (pitten, herdemann und kramer ) nur auf trockenen händen anzulegen. die einfache händewaschung beinhaltet die anwendung einer waschlotion ohne antimikrobielle wirkung mit dem ziel, die hände zu reinigen. die einfache händewaschung ist einmalig zu arbeitsbeginn indiziert, um schmutz und bakteriensporen zu entfernen. risikoabhängig kann sie auch vor essenzubereitung und -verteilung, nach toilettenbenutzung außer bei durchfall und nach dem naseputzen außer bei atemweginfektionen durchgeführt werden. waschlotionen müssen frei von pathogenen sein. wegen der hautverträglichkeit sollte der ph-wert neutral oder schwach sauer sein. nach dem waschen muss die haut abgetrocknet werden, um hautschäden vorzubeugen. anstelle fester seifen ist der einsatz flüssiger seifen zu empfehlen, da erstere häufig kontaminiert waren und nach einführung flüssiger seife die rate von ni abfiel (Şenol, Çakan und Özacar ) . die verwendung von einmalflaschen ist zu empfehlen, weil aufbereitung und nachfüllen mit kontaminationsrisiken verbunden sind. im fall eines ausbruchgeschehens sollten auch flüssige seifen in umgebungsuntersuchungen einbezogen werden, da diese vereinzelt quelle für gramnegative bakterien waren (archibald et al. ; grohskopf et al. ; sartor et al. ) . die hautverträglichkeit von seifen ist in allen merkmalen (transepidermaler wasserverlust, entfettung, hautrauhigkeit, schuppung, austrocknung) signifikant schlechter als die anwendung alkoholischer händedesinfektionsmittel (kramer et al. ). die hygienische händewaschung beinhaltet die anwendung einer antimikrobiellen waschlotion mit dem ziel, die hände zu reinigen und gleichzeitig eine gewisse bakterizide wirkung zu erzielen. die hygienische händewaschung ist im krankenhaus keine alternative zur händedesinfektion (kramer et al. b ). die hygienische händedesinfektion beinhaltet die anwendung eines alkoholischen händedesinfektionsmittels nach tatsächlicher oder fraglicher kontamination der hände bzw. vor bestimmten tätigkeiten. indikationen: vor folgenden situationen wird die hygienische händedesinfektion, angelehnt an die momente der händedesinfektion der who, empfohlen (› abb. durchführung: die hygienische händedesinfektion ist so durchzuführen, dass die transiente flora noch auf den händen weitestgehend abgetötet wird. das alkoholische händedesinfektionsmittel ist über sämtliche bereiche der trockenen hände mit besonderer berücksichtigung der fingerspitzen, daumen, innen-und außenflächen, handgelenke, interdigitalräume und nagelfalze einzureiben. die hautareale sollen für die dauer der deklarierten einwirkzeit feucht benetzt sein. es ist eine einreibetechnik zu wählen, die sicherstellt, dass beide hände möglichst vollständig benetzt sind. für eine akzeptable benetzung der hände ist das verreiben des präparats für - s erforderlich ). bei mutmaßlicher/wahrscheinlicher viruskontamination muss ein gegen die entsprechenden viren wirksames präparat verwendet werden (valide prüfergebnisse). alkoholische händedesinfektionsmittel sind innerhalb von s hoch wirksam gegenüber bakterien einschließlich mre, hefepilzen und behüllte viren (kampf und kramer ) . dagegen benötigen alkoholische gele mit niedrigem alkoholgehalt min (kramer et al. ) und waren wegen der geringeren wirksamkeit trotz verbesserter compliance ohne einfluss auf die ni-rate (rupp et al. ). gegenüber unbehüllten viren sind nur wenige alkoholische desinfektionsmittel innerhalb klinisch vertretbarer einwirkzeit wirksam ). diese präparate weisen eine unterschiedliche einwirkzeit ( bzw. min) auf und sind aufgrund der zusammensetzung unterschiedlich gut hautverträglich (kampf und reichel ) . die effektivität der händedesinfektion ist sowohl anhand der senkung der ni-rate insgesamt (capretti et al. ; pitten et al. ) als auch für spezielle merkmale nachgewiesen wie senkung von zvk-assoziierten blutstrominfektionen (capretti et al. ; larson, quiros und lin ) , hwi und ssi (hilburn et al. ) , herabsetzung von mrsa-infektionen und der nachweisrate klinischer mre-isolate (gagné, bédard und maziade ; harbarth et al. ; harrington et al. ; johnson et al. ; kaier et al. ; ling und how ; macdonald et al. ). selbst in kommunalen settings war eine präventive wirkung in bezug auf gastrointestinale und respiratorische infektionen nachweisbar (guinan, mcguckin und ali ; hammond et al. ; hübner et al. ; lee et al. ; sandora et al. ; white et al. ) . die compliance der händehygiene liegt im gesundheitswesen bei durchschnittlich etwa %. somit wird die händedesinfektion nur bei etwa der hälfte der situationen mit erforderlicher händedesinfektion durchgeführt. durch die verbesserung der compliance von % auf % konnte gezeigt werden, dass die ni-rate um % sank (pittet et al. ) . keine andere einzelmaßnahme der krankenhaushygiene hat einen so großen nachweislichen präventiven nutzen. die compliance kann z. b . durch verwendung besonders hautverträglicher händedesinfektionsmittel, einfachen zugang zum desinfektionsmittel, verbrauchsanalysen, surveillance von ni, schulung und förderung der händehygiene, appell an die vorbildfunktion der vorgesetzten, vermeidung von personalengpässen in der patientenversorgung, automatische spender und standardisierte arbeitsabläufe (z. b. beim legen eines peripheren venenkatheters) verbessert werden (kampf et al. ; kampf, löffler und gastmeier ; sahud und bhanot ) . die chirurgische händedesinfektion wird präoperativ mit dem ziel durchgeführt, die transiente flora der hände zu eliminieren und die residente flora der hände für die dauer der op größtmöglich zu reduzieren. durch die chirurgische händedesinfektion soll das ssi-risiko gesenkt werden, da op-handschuhe in bis zu % bemerkt oder unbemerkt perforieren (harnoss et al. (harnoss et al. und und perforierte op-handschuhe mit einem höheren ssi-risiko verbunden sind (cruse und foord ; misteli et al. ). die verwendung einer nichtmedizinischen seife hatte einen ssi-ausbruch zur folge (grinbaum, de mendonç und cado ) . indikationen: die chirurgische händedesinfektion ist vor allen operativen eingriffen durchzuführen (krinko ) sowie vor sonstigen eingriffen mit gleichen anforderungen an die asepsis. es wird empfohlen, die hände zu dienstbeginn zu waschen, spätestens aber vor anlegen der op-bereichskleidung in der op-schleuse (kramer et al. b ). die hände und fingernägel der mitarbeiter müssen sauber sein, wenn sie den op-trakt betreten. vor dem anlegen der op-bereichskleidung wird eine hygienische händedesinfektion durchgeführt. durchführung: bei optisch sauberen händen ist routinemäßig keine waschung vor der desinfektionsphase erforderlich. die fingernägel sind nur bei verschmutzung mit weicher, thermisch desinfizierter (oder steriler) kunststoffbürste, ggf. zusätzlich mit holzstäbchen oder metallnagelreiniger zu säubern. hände und unterarme sind wegen der wegbereitung von hautirritationen nicht mit der bürste zu behandeln. anschließend werden die hände mit frischem einmaltextil-oder papierhandtuch getrocknet. zur desinfektion werden hände und unterarme nach der vom hersteller an-gegebenen einwirkzeit vollständig mit dem desinfektionsmittel benetzt. anschließend werden die hände an der luft getrocknet, bevor die op-handschuhe angelegt werden (krinko ) . alkoholische händedesinfektionsmittel: da alkohole, insbesondere propan- -ol, gegen die residente hautflora hochwirksam sind, wurde die anwendung von propan- -ol ( %) über min zum referenzverfahren für die chirurgische händedesinfektion ausgewählt. durch die referenzdesinfektion lässt sich die koloniezahl der hände um , log -stufen reduzieren (sofortwirkung). nach h unter dem op-handschuh ist die koloniezahl der hände noch immer um , log -stufen niedriger (kampf und ostermeyer ) . ein präparat zur chirurgischen händedesinfektion darf der referenzdesinfektion weder in der sofort-noch in der langzeitwirkung unterlegen sein. abhängig vom präparat sind auch innerhalb von , min gleichwertige wirksamkeitsergebnisse erzielbar wie nach einer anwendung über min (kampf, ostmeyer und heeg ) . jedoch haben kleine volumina wie ml abhängig von der größe der hände eine schlechtere wirksamkeit, auch wenn die hände über die dauer der einwirkungszeit mit dem präparat benetzt gehalten werden (kampf und ostermeyer ) . bei bemerkter intraoperativer handschuhbeschädigung müssen neue sterile op-handschuhe angelegt werden. vor dem anlegen der neuen op-handschuhe ist eine alkoholische händedesinfektion für mindestens s durchzuführen (kampf, ostermeyer und kohlmann ) . ist die hand durch blut verschmutzt bzw. hat sich handschuhsaft angesammelt, ist sie vor der desinfektion mit einem sterilen tuch zu reinigen. hat sich die perforation kurz vor op-ende ereignet, kann es ausreichen, einen neuen sterilen handschuh über den perforierten handschuh zu ziehen (arbeitskreis krankenhaus-und praxishygiene der awmf ). für das operativ tätige team wird bei eingriffen mit erhöhtem perforationsrisiko das tragen von zwei paar übereinander gezogener op-handschuhe (double gloving) empfohlen (thomas, agarwal und mehta ) , da indikatorhandschuhe die perforation nicht mit ausreichender sicherheit anzeigen (partecke et al. ). für die viszeralchirurgie wird aufgrund des anstiegs der perforationsrate und des ab min nachweisbaren bakterientransfers durch die perforationen ein wechsel der op-handschuhe für operateur und ersten assistenten nach spätestens min, für weitere assistenten und op-pflegepersonal nach min empfohlen (harnoss et al. ; partecke et al. ), sofern kein double gloving bevorzugt wird. handschutz und handpflege sind als berufliche pflicht aufzufassen, weil eine geschädigte haut nicht mehr so gut desinfizierbar ist und in ein irritativ-toxisches kontaktekzem mit berufsunfähigkeit münden kann. eine gesunde haut ist voraussetzung für eine effektive händedesinfektion (mäkela ) . um der hautirritation vorzubeugen, müssen hautschutz und hautpflege systematisch und konsequent erfolgen (› kap. . ): • hautschutzpräparate werden bereits vor dem kontakt mit wasser und desinfektionsmitteln aufgetragen. • hautpflegeprodukte werden nach dienstschluss und in der freizeit angewandt. der protektive effekt von hautschutzpräparaten wurde in hautirritationsmodellen (fluhr et al. ; frosch und korte ; gehring ) und im op-arbeitsbereich (berndt et al. ) nachgewiesen. für die wirksamkeit war die regelmäßige, häufige und korrekte anwendung rückfettender externa entscheidend, weniger der zeitliche bezug zur wasser-und desinfektionsmittelexposition. hautpflegemittel sollen wegen der kontaminationsgefahr bei der entnahme in spendern oder tuben bereitgestellt werden. bei gefährdung der haut durch arbeiten im feuchten milieu -dazu gehört auch das tragen flüssigkeitsdichter handschuhe > hmuss der arbeitgeber psa bereitstellen, eine betriebsanweisung und einen hautschutzplan erstellen, die möglichkeit zur reduzierung der feuchtigkeitsexposition einschließlich ersatzstoffprüfung überprüfen und die arbeitsmedizinische vorsorge und Überwachung gewährleisten (trba von ) . im hautschutzplan sind die präparate für reinigung, schutz und pflege der haut festzulegen. bei beginnenden hautschäden ist unverzüglich der betriebsärztliche dienst zu konsultieren. bei der auswahl von hautschutz-und hautpflegepräparaten ist der hauttyp (seborrhoisch oder sebostatisch) zu beachten. wegen des risikos der sensibilisierung und der penetrationsförderung durch harnstoff sind produkte ohne duft-und ohne konservierungszusatz mit einem harnstoffgehalt < % zur bevorzugen. wegen der besseren hautverträglichkeit sind natürliche fettsäuren mineralölderivaten überlegen. Üblicherweise werden händedesinfektionsmittelspender mit einmalflaschen bestückt und sollen folgende anforderungen erfüllen (assadian ): • bestückung ausschließlich mit nicht wiederbefüllbarem desinfektionsmittelgebinde; bei wiederbefüllen durch "top-up" sind die hygienischen rahmenbedingungen in form einer sop festzuschreiben, deren einhaltung zu dokumentieren ist. • die spender sollen die verwendung von händedesinfektionsmittelgebinden verschiedener hersteller erlauben. • die spender müssen so betrieben und gewartet werden können, dass eine mikrobielle kontamination des pumpkopfs vermieden wird. • das händedesinfektionsmittel muss leicht identifizierbar und der füllstand im spender erkennbar sein. • die außen-und innenteile des spenders müssen wischdesinfizierbar sein. • die spender sowie alle permanenten teile müssen maschinell thermisch bei einem ao-wert von mindestens °c (z. b. °c/ min) aufbereitbar sein. • spender mit einwegpumpköpfen, die mit dem leeren desinfektionsmittelgebinde zu entsorgen sind, bzw. berührungslos arbeitende spender sind zu bevorzugen. werden die pumpköpfe für nachfolgende gebinde verwendet, muss eine detaillierte aufbereitungsanweisung benannt werden. • aus juristischen gründen ist eine dauerhaft lesbare etikettierung der spender mit einem warnhinweis zu empfehlen, z. b. "händedesinfektionsmittel ausschließlich zum gebrauch auf der hand! kein trinken, verspritzen in die augen oder auftragen auf schleimhäute" • es ist als ideal anzusehen, wenn der spender mechanisch oder elektronisch daten zum desinfektionsmittelverbrauch liefert. rechtlich ist ein umfüllen möglich, sofern das unter der unmittelbaren fachlichen verantwortung des anwendenden arztes oder apothekers erfolgt. der umfüllende haftet für sein hergestelltes produkt. ein umgefülltes desinfektionsmittel darf nicht an andere abgegeben werden. aus medizinischer sicht und aus haftungsrechtlichen gründen müssen hygienische mindeststandards beachtet werden. diese umfassen die reinigung und sterilisation der desinfektionsmittelbehälter vor neubefüllung, das umfüllen unter aseptischen behältnissen (sterile werkbank), dokumentation der chargennummer bzw. umfülldatum und durchführung durch geschultes personal (hengesbach und schneider ) . die notwendigkeit für dieses vorgehen kann daraus abgeleitet werden, dass bakteriensporen in alkoholbasierten desinfektionsmitteln überleben können und auf diesem weg z. b . in eine wunde gelangen könnten (theoretisches risiko von gasbrand und tetanus; danchaivijitr et al. ; weuffen, berling und hetmanek ) . das tatsächliche risiko ist jedoch minimal. so konnten im händedesinfektionsmittel nach längerem stehenlassen der geöffneten flasche in % der proben bakteriensporen gefunden werden, jedoch weniger als eine spore pro ml händedesinfektionsmittel. in keinem fall wurden sporen pathogener bakterienspezies identifiziert ). axel kramer und ojan assadian sir john pringle prägte den begriff "antisepsis". mit der einführung des karbolwundverbands durch lister wurde die antiseptik zur prävention von ssi etabliert. unter antisepsis (griech. anti = gegen, sepsis = fäulnis) werden alle lokal angewandten maßnahmen zur abtötung oder inaktivierung von mikroorganismen am oder im lebenden gewebe verstanden, die aus prophylaktischer indikation (prophylaktische antiseptik) einer unerwünschten kolonisation oder infektion vorbeugen oder aus therapeutischer indikation (therapeutische antiseptik) diese behandeln. die antiseptik wird in erster linie durch einmalige oder wiederholte topische anwendung von antiseptika realisiert. zur wundantiseptik werden jedoch auch biologische (z. b. madentherapie; daeschlein et al. b ) und physikalische verfahren (z. b. pulsierender gleichstrom und niedertemperatur-plasma; daeschlein et al. a , kramer et al. c ) eingesetzt. zielsetzung der prophylaktischen antiseptik ist die infektionsverhütung durch unterbindung des erregertransfers von kontaminierten bzw. kolonisierten in mikrobiell nicht besiedelte körperbereiche, die sanierung unerwünschter kolonisation, die normalisierung einer dysbiose bzw. die abtötung potenzieller pathogene nach akzidenteller kontamination. • zur prophylaktischen antiseptik, die im allgemeinen einmalig oder kurzfristig wiederholt stattfindet, werden rasch wirksame mikrobiozide (in speziellen fällen auch viruzide) wirkstoffe benötigt. • zur therapeutischen antiseptik sind aufgrund der wiederholten applikation und langfristigen einwirkung ggf. auch mikrobiostatische (bzw. virustatische) wirkstoffe ausreichend. aus therapeutischer indikation eingesetzte antiseptika werden auch als lokale antiinfektiva bezeichnet. die wirkungsanforderungen an antiseptika sind in der testhierarchie der europäischen prüfnormen definiert. bei praxisrelevanter belastung sollen in vitro ≥ kbe der für die testung festgelegten mikroorganismenspezies abgetötet werden (kramer ) . für die verträglichkeitsprüfung ist bisher kein einheitlicher prüfablauf festgelegt. die irritationspotenz kann zunächst an der chorioallantoismembran des hühnereis geprüft werden (kramer und behrens-baumann ) . die gewebeverträglichkeit wird in zell-und gewebekulturen einschließlich dreidimensionaler in-vitro-modelle ermittelt, ggf. danach, falls zwingend erforderlich, tierexperimentell (geerling et al. ) oder, wenn der wirkstoff toxikologisch und präklinisch als ausreichend untersucht gilt, für wundantiseptika ohne zwischenstufe direkt an mesh-graft-entnahmestellen (eisenbeiß et al. sofern der wirkmechanismus auf einer unspezifischen zerstörung der mikroorganismen beruht (z. b. bei alkoholen, pvp-iod, natriumhypochlorit, oct, polihexanid) , ist keine resistenzentwick lung zu befürchten. richtet sich die wirkung gegen mikrobielle enzyme oder transporter, ist eine resistenzentwicklung möglich. so werden zunehmend staphylokokkenisolate mit verminderter invitro-empfindlichkeit gegen chx beschrieben, beruhend auf plasmid-kodierten effluxpumpen in der zellmembran (fritz et al. ; ho et al. ; horner, mawer und wilcox ; lee et al. ; mcgann et al. ; mcneil et al. ; otter et al. ; tattawasart et al. ) . aufgrund des spezifischen angriffspunkts in der bakterienzelle und der mit der resistenzentwicklung gegen antibiotika vergleichbaren mechanismen bei der resistenzentwicklung gegen triclosan (targetmutation, erhöhte targetexpression, aktiver efflux aus der zelle, enzymatische inaktivierung/abbau) sind laborbefunde zu kreuzresistenzen zwischen triclosan und antibiotika nicht überraschend. die in vitro durch triclosan induzierbare resistenzentwicklung kann mit einer gleichzeitigen resistenzentwicklung gegen antibiotika einhergehen (braoudaki und. hilton , russel, maillard und fuur , sanchez, moreno und martinez . inzwischen wurden auch resistente stämme in der umwelt isoliert (drury et al. ) . vor jeder antiinfektiven prophylaxe oder therapie muss anhand folgender kriterien die entscheidung zwischen antiseptik oder antimikrobieller chemotherapie getroffen werden: • erreicht oder übertrifft die lokale anwendung die effektivität einer antimikrobiellen chemoprophylaxe bzw. -therapie? • ist die lokale anwendung ohne risiko von nebenwirkungen? die hautantiseptik ist vor allen durchtrennenden eingriffen der haut notwendig, d. h. vor injektion, punktion, dem legen von gefäßkathetern und zur laufenden antiseptik bei liegendem gefäßkatheter (sog. katheterpflege) sowie präoperativ. als antiseptische körperwaschung dient sie bei einer kolonisation mit mrsa der dekolonisation z. b. vor elektiven operativen eingriffen sowie bei kolonisation/infektion mit anderen mre zur herabsetzung des risikos ihrer weiterverbreitung, z. b. bei its-patienten. mittel der wahl sind alkohole ohne remanenten zusatz. da sich die einwirkungszeit zwischen talgdrüsenarmen und -reichen hautarealen unterscheidet, ist die vom hersteller deklarierte verlängerte einwirkungszeit auf talgdrüsenreicher haut z. b. vor da der talgdrüsenanteil der haut regional unterschiedlich ist und der fettgehalt individuellen schwankungen unterliegt, ist man bei der präoperativen hautantiseptik auf der sicheren seite, wenn auch auf talgdrüsenarmen arealen die präoperative hautantiseptik mit der einwirkungszeit für talgdrüsenreiche haut zugrunde gelegt wird. mit alkoholhaltigen präparaten wird beim auftragen ohne anschließendes mechanisches einreiben für s eine reduktion auf der hautoberfläche nur um etwa , log erreicht (ulmer et al. ). außerdem dringt der alkohol nicht in die haarfollikel ein (ulmer et al. (ulmer et al. , . wirkstoffauswahl: da in den usa und vielen europäischen staaten bisher überwiegend chx-haltige antiseptika eingesetzt werden, wurden fast alle studien mit diesem wirkstoff durchgeführt. oct übertrifft in vitro chx an wirksamkeit (koburger et al. ), ist in kombination mit alkoholen vergleichbar effektiv in bezug auf die reduktion der hautflora um die insertionsstelle des zvk, induziert im gegensatz zu chx keine resistenzentwicklung (al-doori, goroncy-bermes und gemmell ), nur selten allergische kontaktekzeme (stingeni, lapomarda und lisi ) und keine igevermittelten anaphylaktischen reaktionen (hübner und kramer , pham et al. . aus diesen gründen und wegen der freisetzung der im chlorhexidinmolekül vorhandenen -chloranilingruppen, die als karzinogen eingestuft sind, was bisher nur in der mundhöhle nachgewiesen wurde (below et al. in vorb.) , spricht die nutzen-risiko-analyse zugunsten von oct. die bei anwendung von chx aufgetretenen schweren anaphylaktischen ereignisse betrafen patienten, bei denen ein chx-imprägnierter gefäßkatheter angelegt wurde (faber et al. ; guleri et al. ; khoo und oziemski ). dem bfarm lagen bis insgesamt berichte aus deutschland über anaphylaktische reaktionen im zusammenhang mit der anwendung von chx vor. es ist zu hoffen, dass durch aussagekräftige endpunktstudien mit oct-haltigen präparaten klarheit über den stellenwert dieses wirkstoffs als ggf. günstigere alternative zu chx geschaffen wird. vor anlage eines zvk ist mit einem alkoholbasierten hautantiseptikums mit zusatz eines remanent wirkenden antiseptikums in ausreichendem abstand um die katheterinsertionsstelle die antiseptik durchzuführen. dadurch wird nicht nur die rekolonisation der haut (reichel et al. , ulmer et al. ) und der katheterspitze signifikant verzögert (dettenkofer et al. (dettenkofer et al. , mimoz et al. ; o'grady et al. ) , sondern auch die inzidenz zvk-assoziierter blutstrominfektionen (capsi) reduziert (huang et al. ) . wirkstoffauswahl: in internationalen empfehlungen gibt es einen breiten konsens zum einsatz chx-haltiger antiseptika zur hautantiseptik vor anlage eines zvk (burrell et al. ) oder zur behandlung der eintrittsstelle beim verbandswechsel (marschall et al. ; o'grady et al. ; tietz, frei und dangel ) . die ausschließliche empfehlung von chx beruht darauf, dass in den usa und vielen europäischen staaten entweder chx oder pvp-iod eingesetzt wird und letzteres chx unterlegen ist. durch -prozentige wässrige lösung von chx und , -prozentige alkoholische chx-lösung wurde die rate von capsi im vergleich zu % wässriger pvp-iod lösung und % ethanol signifikant reduziert (maki, ringer und alvarado , valles et al. ). in einer multizentrischen, prospektiven, randomisierten, kontrollierten studie war dagegen zwischen , % chx-tinktur vs. % wässriger pvp-iod lösung kein signifikanter unterschied in der kolonisation der katheterspitze und bezüglich der capsi-rate nachweisbar (humar et al. ) . im ergebnis eines cochrane review (huang et al. ) und einer nachfolgenden metaanalyse (maiwald und chan ) kann sowohl die katheterkolonisation als auch die cabsi-rate durch alkoholhaltige formulierungen mit chx-zusatz im vergleich zu % wässriger pvp-iod lösung signifikant reduziert werden. als fazit wird in der cdc guideline (o'grady et al. ) die hautantiseptik mit alkoholischen formulierungen mit zusatz von > , % chx bzw. in der aktuellen epic guideline (loveday et al. ) von % chx in kombination mit -prozentigem propan- -ol empfohlen. bei kontraindikationen gegen chx können alternativ iodtinktur, iodophore oder % ethanol verwendet werden. es findet sich kein hinweis auf oct, da dieser wirkstoff in den angloamerikanischen ländern nahezu unbekannt ist. oct kommt aus folgenden gründen als aussichtsreicher remanenter zusatz zu alkoholen in betracht. es ist in vitro mikrobiozid signifikant wirksamer als chx (koburger et al. ) . auch in der remanenten wirkung war oct in einem d-modell der haut beim vergleich äquimolarer wirkstoffkonzentrationen chx überlegen. für epidermal gebundenes chx war keine oder eine nur sehr geringe remanente mikrobiozide wirksamkeit gegenüber p. aeruginosa nachweisbar, während beim gebundenen oct reduktionsfaktoren zwischen , - , log entstehen ). daher ist da-von auszugehen, dass oct-haltige alkoholische formulierungen auch bei anwendung auf der haut die wirksamkeit von chx erreichen bzw. übertreffen (hübner, siebert und kramer ) . auch bezüglich der biokompatibilität war oct überlegen (müller und kramer ) . in zwei bisher durchgeführten klinischen studien bei nicht getunnelten zvk wurde die höhere wirksamkeit des oct-zusatzes im vergleich zur analogen alkoholischen formulierung ohne oct-zusatz anhand der reduktion der kolonisation an der insertion sowohl im sofortwert als auch nach h (dettenkofer et al. ) sowie anhand der anzahl positiver kulturen an der katheterspitze (dettenkofer et al. ) nachgewiesen. die inzidenz von capsi wurde nur tendenziell reduziert, offensichtlich war die stichprobengröße nicht ausreichend. auf die insertionsstelle aufgebrachte antibiotikahaltige salben besitzen eine unsichere wirksamkeit (zhang et al. ) und sind wegen des risikos der resistenzentwicklung sowie der schaffung eines feuchten milieus abzulehnen. letzteres trifft auch für mupirocin zu, da bereits highlevel-resistenzen beschrieben sind (zhang et al. ) . daher wird analog wie vor der katheterinsertion bei jedem verbandswechsel eine hautantiseptik mit alkohol basierten formulierungen mit zusatz von > , % chx (maki et al. ) bzw. mit % chx in % propan- -ol (loveday et al. ) empfohlen. zur kontinuierlichen applikation antiseptischer substanzen direkt am kathetereintritt stehen ein chx-getränkter schwamm (z. b. biopatch ™ ; roberts und cheung ) in verbindung mit einem semipermeablen folienverband sowie die direkte integration eines durchsichtigen, chx-haltigen gelkissens in einen semipermeablen folienverband (z. b . tegaderm ™ m chg) (pfaff, heithaus und emanuelsen ; scheithauer et al. ) zur verfügung. einige präventionsbündel haben antiseptisch wirksame verbände eingeschlossen (hatler et al. ; guerin et al. ; miller und maragakis ; shapey et al. ). eine metaanalyse (ho und litton ) zum einsatz des biopatch ™ am zvk und an epiduralen kathetern zeigte eine signifikante reduktion der kolonisationsdichte im bereich der eintrittsstelle und als trend eine verminderte device-assoziierte infektionsrate. in weiteren studien konnte der infektionspräventive nutzen chx-haltiger verbände am zvk bestätigt werden (camins et al. ; levy, katz und solter ; ruschulte et al. ; timsit et al. timsit et al. , . da im michigan-keystone-projekt (berenholtz et al. (berenholtz et al. , pronovost, berenholtz und needham ; pronovost et al. pronovost et al. , safdar, fine und maki ) und in anderen initiativen zur senkung der infektionsraten (krein et al. ; saint et al. ; zingg et al. zingg et al. , auch ohne den einsatz dieser kostenintensiven hilfsmittel nachhaltige effekte erreicht wurden, empfehlen die aktuellen britischen und u. s.-amerikanischen empfehlungen mit ausnahme der american pediatric surgical association (huang et a. ) den einsatz chx-haltiger verbände nur bei hochrisikopatienten oder zur reduktion anhaltend hoher infektionsraten erst nach stringenter implementierung konventioneller präventionsmaßnahmen. • der stellenwert chx-haltiger verbände bei patienten mit gleichzeitiger chx-ganzkörperwaschung ist ungeklärt. • für arterielle katheter liegen bisher nur ergebnisse einer tendenziellen reduktion der infektionsrate vor (timsit et al. ). • während beim zvk die höhere wirksamkeit von hautantiseptika mit remanentem zusatz im vergleich zu rein alkoholischen formulierungen anhand der capsi-rate gesichert ist, ist beim peripheren venenkatheter bisher nur nachgewiesen, dass durch verwendung von hautantiseptika mit remanentem zusatz die anzahl kolonisierter bzw. kontaminierter katheter reduziert wird (small et al. ). zielsetzung ist die herabsetzung der erregerlast auf der haut (popovich et al. ), um abhängig vom endemischen niveau sowohl das risiko der erregertransmission (climo et al. ) als auch einer ni (climo et al. , huang et al. durch vormals die haut des patienten besiedelnde erreger zu senken. darüber hinaus ist die antiseptische ganzkörperwaschung eine additive maßnahme zur prävention von crbsi vor allem dann, wenn die implementierung anderer präventionsstrategien die crbsi raten nicht adäquat senken können. im ergebnis einer -jährigen retrospektiven studie mit täglicher ganzkörperwäsche mit oct-haltiger seife auf einer its wurde die besiedlung mit mrsa um % reduziert, allerdings traf das nicht gleichermaßen auch für die rate von capsi zu (spencer et al. ) . zum teil erwies sich eine chx-haltige ganzkörperwäsche in unterschiedlichen its-settings auch effektiv zur prävention von trägertum und capsi durch mrsa und vre sowie zur reduktion der körperbesiedlung durch a. baumanii auf its mit endemischer situation dieses erregers bei capsi (borer et al. ). in einer multizentrischen europäischen studie auf its konnte durch verbesserte händehygiene in verbindung mit chx-körperwaschung die akquisition von mre, speziell von mrsa, signifikant reduziert werden, während aufnahmescreening und isolierung keinen signifikanten einfluss hatten (derde et al. ). als risiko bei einer zunehmenden anwendung von chx ist zu berücksichtigen, dass mrsa-stämme, die das qaca/b gen tragen, nicht beeinflusst bzw. sogar rascher verbreitet werden (batra et al. ; otter et al. ) . da intensivpatienten in jedem fall gewaschen werden müssen, kann der einsatz antiseptischer körperwaschlotionen als sinnvolle additive maßnahme der infektionsprävention bei dieser patientengruppe insbesondere zur risikominimierung der weiterverbreitung von mrsa, vre und actinetobacter spp. angesehen werden. außerdem wurde durch tägliches bad mit chx basierter ganzkörperwäsche eine signifikante senkung der rate von crbsi von , auf , pro kathetertage bzw. kontaminierter blutkulturen von . auf . pro patiententage erzielt, was sich in mehreren studien (bleasdale et al. ; climo et al. ; evans und dodge ; karki und cheng ; munoz-price et al. ; o'horo et al. ; popovich et al. ) und im ergebnis eines sys-tematischen reviews (afonso, llauradó und gallart ) bestätigt. zugleich wurde die kontamination von personal und umgebung reduziert (afonso, llauradó und gallart ) . sogar die sepsisrate konnte reduziert werden (huang et al. ) . in einer metaanalyse von studien (o'horo et al. ) auf internistischen intensivstationen mit anwendung chx-haltiger waschtücher ( %) oder ganzkörperwaschung ( %) wurde für beide anwendungen eine signifikante herabsetzung von crbsi gesichert. milstone et al. ( ) untersuchten den einfluss der täglichen ganzkörperwaschung mit chx-haltigen waschtüchern bei pädiatrischen intensivpatienten jenseits des zweiten lebensmonats in einer multizentrischen nicht verblindeten studie mit cluster-randomisiertem crossover-design mit dem ergebnis einer signifikante reduktion der inzidenz von crbsi. % der kinder mussten aufgrund einer unverträglichkeit aus der studie genommen werden. da entgegen der definition der cdc alle, meist über zvk abgenommenen, positiven blutkulturen bei patienten mit infektionszeichen als crbsi gezählt wurden und die inzidenzraten über denen von präventionsbündelstudien ohne chx-ganzköperwaschung lagen, relativiert das nach aussage der autoren die aussagekraft. dagegen wurde die rate von sekundären bsi, c.-difficile-infektionen, vap und katheter-assoziierten hwi nicht beeinflusst (popovich et al. ). präoperativ sind für die ohrmuschel alkoholhaltige hautantiseptika mit remanentem zusatz zu bevorzugen. da eine ssi der ohrmuschel der op-erfolg infrage stellt, hat es sich bewährt, die einwirkzeit auf mindestens min zu verlängern, z. b. durch auflage die ohrmuschel bedeckender getränkter tupfer. im mittelohr ist chx wegen der neurotoxizität kontraindiziert. infrage kommen wässrig basierte zubereitungen mit gehalt von , % polihexanid oder , % pvp-iod. allerdings liegen hierzu keine studien vor. da die details in den jeweiligen klinischen kapiteln behandelt werden, soll ein tabellarischer Überblick über wichtige indikationen und infrage kommende wirkstoffe genügen (› tab. . ) . für die schleimhautantiseptik ist oct vom grundsatz her wegen der höheren und rascher einsetzenden wirksamkeit polihexanid und chx überlegen. obwohl die wundbehandlung eine herausforderung für die menschheit seit der menschwerdung ist, fehlt bis heute die evidenz für ein allgemein akzeptiertes behandlungskonzept auf naturwissenschaftlicher/molekularbiologischer grundlage, dass durch rcts und metaanalysen verifiziert ist. deshalb müssen die zur verfügung stehenden befunde zur wirksamkeit und verträglichkeit antiseptischer präpa- rate von der in-vitro-testung bis zur vereinzelt existierenden rct-studie einschließlich limitierter metaanalysen zu einer plausiblen synopse zusammengeführt werden (kramer et al. c ). wundantiseptika sind nur nach sorgfältiger indikationsstellung und vorausgehender wundkonditionierung anzuwenden. andernfalls können wundheilungsstörungen verursacht werden bzw. können die antiseptika ihre wirkung nicht entfalten. grundsätzlich müssen alle wunden als kontaminiert angesehen werden. das bedeutet jedoch nicht, dass alle kontaminierten wunden eine infektion entwickeln. da die physiologische kolonisation von wunden für den wundheilungsverlauf irrelevant ist (eisenbeiß et al. ), wurde als hilfestellung für die abschätzung des infektionsrisikos der wounds at risk score entwickelt (› tab. . ) . bei der entwicklung dieses risikoscores werden sowohl die wunde exogen belastende faktoren als auch die infektionsanfälligkeit des patienten berücksichtigt. die indikation für den einsatz von antiseptika ergibt sich aus der addition unterschiedlich zu gewichtender gefährdungsursachen, für die punkte vergeben werden. bei > punkten ist eine antiseptische behandlung zu rechtfertigen (dissemond et al. ). unabhängig von der sich aus dem score ergebenden indikation ist eine dekolonisation von wunden bei nachweis von mre indiziert. verletzungen sind abhängig von der kontamination und dem ausmaß der gewebeschädigung mehr oder stark infektionsgefährdet. aus diesem grund ist die antiseptische primärversorgung ver-schmutzter wunden einschließlich verätzungen und verbrennungen notwendig. bei biss-und stichverletzungen steht die erforderliche tiefenwirkung des antiseptikums im vordergrund. in auswertung des schrifttums zum mikrobiellen spektrum und zu den risikofaktoren bei bissverletzungen wurden folgende emp fehlungen zum management bei bisswunden abgeleitet ): • bei der frischen offenen verletzung ggf. chirurgisches débridement, danach antiseptische spülung der wunde mit einem kombinationsprodukt aus pvp-iod und ethanol (z. b. betaseptic ® ), keine antibiotikaprophylaxe, primärverschluss • bei der nahezu geschlossenen frischen verletzung (z. b. katzenbiss) ggf. chirurgisches débridement, auflage antiseptisch getränkter kompressen für etwa min mit zwischenzeitlicher tränkung (z. b. betaseptic ® ), keine antibiotikaprophylaxe • bei der älteren verletzung nach etwa h ggf. chirurgisches débridement, auflage antiseptisch getränkter kompressen oder verbände für etwa min mit zwischenzeitlicher tränkung (z. b. betaseptic ® ), parallel einmalige iv. oder dosisadaptiert orale gabe von antibiotika (amoxicillin/clavulansäure) • bei der älteren verletzung nach etwa h chirurgisches débridement, danach antiseptische spülung der wunde (z. b. betaseptic ® ). bei klinisch ersichtlicher infektion/entzündung chirurgische revision mit eröffnung und antiseptik sowie antibiotikatherapie gemäß antibiogramm (empirischer beginn mit ampicillin oder amoxicillin/clavulansäure). bei jeder bissverletzung müssen der tetanusimpfstatus und das risiko der tollwutexposition abgeklärt werden. gleiches gilt bei seltenen, doch gelegentlich stattfindenden humanen bissen für die risikoabschätzung für lues, hbv, hcv und hiv. octenidin (› tab. . ) oct und pvp-iod erreichen im keimträgertest die antiseptische effektivität rascher (≥ s) als chx (≥ min) und polihexanid (> min) (schedler et al. in vorb) . durch bindung von oct an die zellmatrix wird ein signifikanter postantiseptischer effekt erzielt (müller et al. ). befunde zur höheren zytotoxizität von oct in der monolayer-zellkultur im vergleich zu iodophoren und polihexanid bedürfen der kritischen interpretation, weil sich oct im wundgewebe an die zellen bindet, wobei die wirksamkeit durch wirkstofffreisetzung in geringen mengen erhalten bleibt, während die zytotoxizität drastisch reduziert wird. durch diese art der "wundversiegelung" dürfte eine nachfolgende wundkolonisation unterbunden werden. oct wird nicht resorbiert, und es sind keine langzeitrisiken einschließlich allergien bekannt. durch oct wird die phagozytose humaner neutrophiler granulozyten gesteigert (steinhauer und goroncy-bermes ) , während der tumornekrosefaktor nicht stimuliert wird (menke et al. ). in konzentrationen von , % wird sowohl oct als auch pvp-iod von erythrozyten toleriert (wagner et al. ). dissemond et al . die relevanz von befunden zur möglichen karzinogenität ist umstritten, weil für den wirkstoff keine genotoxizität nachgewiesen ist. daher bliebe für eine karzinogene wirkung nur die erklärung einer epigenetischen nicht genotoxischen veränderung der dna übrig. im ergebnis der Überprüfung wurde weder oxidativer stress induziert, noch waren eine hydroxylierung oder hypermethylierung der dna oder eine signifikante produktion mitogener zytokine und des transkriptionsfaktors nf-κb nachweisbar. auch der status der gap-junctions (gjic) wurde nicht signifikant beeinflusst. damit waren keine eindeutigen epigenetischen einflüsse nachweisbar (creppy et al. ) und es werden die einschätzungen der epa ( , , a) und später der australischen behörde ocseh ( ) untermauert. diese leiten aus den tierexperimentellen daten von horner ( ) und milborne ( ) ab, dass kein relevantes gesundheitsrisiko für den menschen erkennbar ist. trotzdem erfolgte die gefahrstoffrechtliche einstufung des rohstoffs polihexanid im rahmen der europäischen chemikaliengesetzgebung in kategorie "kann vermutlich krebs erzeugen". produkte, die > % polihexanid enthalten, müssen danach als karzinogen klasse gekennzeichnet werden. die europäische chemikalienagentur (echa) kam auf basis der zwei zitierten nagetierstudien zu dem schluss, dass nicht jegliches gesundheitsrisiko für den menschen mit absoluter sicherheit ausgeschlossen werden könnte. zu dieser feststellung muss jedoch die einschränkung getroffen werden, dass das design der beiden studien nicht den aktuellen anforderungen entspricht und die effekte nur bei hoher dosierung (ca. ppm/ , %), die wahrscheinlich die maximale tolerierbare dosis überschreitet, auftraten. da arzneimittel oder medizinprodukte in der regel , - , % polihexanid enthalten und der wirkstoff nicht resorbiert wird, ist eine gesundheitsgefährdung bei antiseptischer anwendung des wirkstoffs auszuschließen. povidon-iod (› tab. . ) pvp-iod bindet elementares iod ohne feste chemische bindung. die eigenschaften des iods bleiben erhalten. abhängig von der umgebenden iodkonzentration wird lediglich die lösungsfähigkeit verändert, wodurch über längere zeit freies iod zur verfügung steht. es wirkt nicht remanent; die wirkung hält nur so lange an, wie die anwesenheit von iod im pvp-trägermolekül gegeben ist. pvp-iod wirkt nicht nur mikrobiozid, sondern bei längerer einwirkzeit sporozid und zusätzlich gegen eine reihe von viren. wegen der allergenen potenz, der resorptionstoxizität für die schilddrüse und der fehlenden remanenz hat pvp-iod zur wundantiseptik in deutschland an bedeutung eingebüßt (kramer et al. c (kramer et al. , c . in einem systematischen review war pvp-iod nicht antiseptisch wirksamen wundauflagen und silbersulfadiazin überlegen, aber in kombination medizinischem honig bezüglich der bakterienelimination und wundheilung unterlegen. im vergleich von studien hält sich die Überlegenheit bzw. unterlegenheit im vergleich zur kontrolle etwa die waage (vermeulen, westerbos und ubbink ) . iodophore sind besser gewebeverträglich als chx-haltige präparate. in vitro setzt bei scheinbar abgetöteten zellen nach abspülen des wirkstoffs wieder die proliferation ein, sog. revitalisierender effekt (müller und kramer ) . in vitro und tierexperimentell ist , -prozentiges pvp-iod im unterschied zu oct knorpelverträglich. genotoxische, karzinogene und teratogene gefährdungen sind nicht bekannt (kramer et al. c ). als liposomale zubereitung (repithel ® ) ist die gewebeverträglichkeit von pvp-iod bei erhaltener wirksamkeit deutlich verbessert, sodass die liposomale pvp-i-zubereitung einer chx-imprägnierten auflage bei anwendung auf mesh graft an wirksamkeit und verträglichkeit überlegen war (reimer et al. ) . bei der anwendung von iodophoren gelten folgende kontra indikationen: hyperthyreose, dermatitis herpetiformis duhring, Überempfindlichkeit gegen iod, radioiodtherapie, peritoneallavage. die anwendung ist sorgfältig abzuwägen und die schilddrüsenfunktion ist zu kontrollieren bei blander knotenstruma, gravidität, stillzeit, großflächiger anwendung bei früh-und neugeborenen sowie bei säuglingen bis zum . lebensmonat. da bei anwendung am auge (präoperativ und zur prävention der ophthalmia neonatorum) die resorbierte iodmenge unterhalb schilddrüsenkritischer werte bleibt (kramer et al. c ), ist bei dieser anwendung keine schilddrüsenfunktionsbeeinflussung zu erwarten. chlorhexidin (› tab. . ) chx und polihexanid unterscheiden sich in der molekülstruktur nur dadurch, dass chx zusätzliche p-chloranilin-reste enthält. daher ist vermutlich die nachgewiesenen abspaltung des p-chloranilins (below et al. in vorb.) für die im unterschied zu polihexanid hohe zytotoxizität, die mutagene potenz (arabaci et al. ; fda ; grassi et al. ; paldy et al. ; souza-junior und castro-prado ) , die induktion von keratosen und dysplasien (sonis, clark und shklar ) sowie die neurotoxizität (aursnes a (aursnes , b bicknell ; kramer et al. kramer et al. , c perez et al. ) verantwortlich. das wachstum von peritonealexplantaten wurde in vitro gehemmt (kramer et al. ); dementsprechend wurde bei tierexperimentellen wunden z. t. eine verzögerte heilung beobachtet (kramer et al. ). beim menschen fiel bei kontaminierten chirurgischen wunden allerdings keine heilungsverzögerung auf (crossfill, hall und london ) . in vitro war chx gegenüber humanen alveolaren knochenzellen zytotoxischer als pvp-lod (cabral und fernandes ) . , -prozentig kommt es am auge zum verlust der oberflächlichen schichten des korneaepithels und der mikrovilli der zweiten schicht (dormans und logten ) . bei irrtümlicher intraoperativer spülung bei kataraktchirurgie mit chx : bzw. : verdünnt kam es zu einer schweren toxischer keratopathie (rij et al. ) . nach -wöchiger anwendung von augentropfen mit chx , % + propamidin , % wurde eine progressive ulzeröse keratitis verursacht, wofür die autoren chx als ursache ansahen (murthy, hawksworth und cree ) . daher wird chx > , % nicht zur ophthalmologischen anwendung empfohlen. nach einer irrigation mit chx , % bei arthroskopischen eingriffen entwickelte sich als frühantwort eine schwere aggressive destruktive arthritis (van huyssten u. bracey , van huyssten . als konsequenz hat chx seine bedeutung zur wundantiseptik verloren und seit ist in der roten liste kein chx basiertes wundantiseptikum enthalten. in japan ist chx seit zur schleimhautantiseptik untersagt. veröffentlichte die medicines & healthcare products regulatory agency (mhra), uk, einen warnhinweis für medizinprodukte und arzneimittel mit gehalt an chx wegen des risikos anaphylaktischer reaktionen mit folgendem hinweis: if a patient experiences an unexplained reaction, check whether chlorhexidine was used or was impregnated in a medical device that was used. ein jahr später warnte swissmedic (swiss agency for therapeutic products) generell von anaphylaktischen reaktion durch anwendung chx haltiger produkte. bei gramnegativen klinischen isolaten wurde eine wirkschwäche nachgewiesen (kramer et al. c ). in vitro ist eine resistenzentwicklung induzierbar (s. o.). natriumhypochlorit (› tab. . ) die weltweite verwendung von naocl begann im ersten weltkrieg nach der wiederentdeckung dieses wirkstoffs durch henry drysdale dakin. wegen der ph-abhängigen instabilität der wässrigen lösung verlor die dakin-lösung ihre bedeutung in der wundantiseptik und erlebt erst jetzt ihre renaissance, nachdem mit der entwicklung einer stabilisierten kombination von naocl und hypochloriger säure (hocl) in wässriger lösung eine stabilität von jahr bzw. eine anbruchstabilität von wochen erreicht wurde. diese wirkstoffkombination (naocl/hocl) erfüllt die in-vitro-anforderungen an wundantiseptika nicht nur gegen vegetative bakterien und sprosspilze (aggarwal et al. ), sondern ist selbst gegen bakteriensporen hoch effektiv (landa-solis et al. ; tana-ka et al. ) . in vitro und bei der behandlung chronischer wunden war die wirkstoffkombination naocl/hocl effektiver und besser verträglich als pvp-iod (abhyankar et al. ; dalla paola et al. ; kapur und marwaha ) . bei der behandlung diabetischer wunden (verblindete rct) wurden die krankenhausverweildauer und die wundheilungsdauer signifikant verkürzt und die wundkategorie signifikant verbessert (hadi et al. ). die besonderheit von naocl/hocl besteht darin, dass es sich um einen physiologischen wirkstoff handelt, der von phagozyten nach auslösung des respiratory burst durch o -metaboliten mittels myeloperoxidase, eosinophiler peroxidase und superoxiddismutase gebildet und rasch durch taurin zu clund wasser entgiftet wird (kramer et al. e ). daher sind für hypochlorit keine langzeitnebenwirkungen zu befürchten und nicht nachgewiesen (gutiérrez ; hasegawa et al. ; kurokawa et al. ; morita, nishida und ito ). in Übereinstimmung dazu wird die proliferation von fibroblasten im unterschied zum zytotoxischen wasserstoffperoxid (wilson et al. ) in vitro nicht durch die noch mikrobiozid wirksame konzentration von hypochlorit gehemmt (crabtree, pelletier und pruett ) . daraus ergibt sich eine hohe therapeutische breite. zusätzlich wundheilungsbegünstigend ist die antiinflammatorische wirkung durch hemmung der zytokinfreisetzung aus mastzellen ohne beeinträchtigung anderer zellfunktionen (medina-tamayo et al. octenidin ist der wirkstoff der wahl für akute kontaminierte traumatische einschließlich mit mre kolonisierte wunden (hübner, siebert und kramer ) . in kombination mit phenoxyethanol (z. b. octenisept ® ) wird die wirkstoffpenetration in die wunde gefördert. für chronische wunden ist die gelzubereitung mit auf , % halbiertem octenidingehalt (z. b. octenilin ® ) zu bevorzugen; sie unterscheidet sich in der wundverträglichkeit nicht von ringer-lösung (eisenbeiß et al. ) . polihexanid ist der wirkstoff der wahl für chronische wunden, reduziert aber auch bei akuten traumata die ssi-rate signifikant (roth et al. in rev.) . polihexanid erreicht nicht die wirksamkeit von oct, fördert aber als einziges wundantiseptikum die wundheilung (hübner und kramer • medizinischer honig: er wurde erfolgreich zur behandlung akuter und chronischer wunden, die eine applikation zulassen, eingesetzt, auch dann, wenn diese mit resistenten bakteriellen krankheitserregern kolonisiert oder infiziert waren oder teilweise nekrotische areale aufwiesen (igelbrink et al. ; simon et al. simon et al. , . für wundauflagen, die silberionen (› tab. . ) freisetzen, kommen zwei metaanalysen und ein review zu dem schluss der unzureichenden evidenz bezüglich der prävention von wundinfektionen und der damit verbundenen wundheilungsförderung bei chronischen wunden. einige studien mit schlechter evidenz sprechen vielmehr für das gegenteil (beam ; storm-versloot et al. ; vermeulen et al. ). in einer rct war bei venösen ulzera weder für den primären noch für den sekundären endpunkt ein positiver einfluss der silberwundauflage nachweisbar (michaels et al. angesprochen wird in der leitlinie auch der umgang mit mp "kritisch b". nach rki/bfarm-empfehlung (rki ) sind diese grundsätzlich maschinell zu reinigen und thermisch zu desinfizieren. diesem grundsatz wurde auch bei der erstellung der leitlinie gefolgt. lediglich in begründeten ausnahmen und nach durchgeführter analyse und bewertung des risikos sind die manuelle reinigung und manuelle chemische desinfektion eine mögliche option. ein nicht beschafftes rdg ist kein grund, auf manuelle verfahren auszuweichen. werden mp mit einem standardisierten verfahren behandelt, sind sämtliche manuellen teilschritte zu dokumentieren; ebenso soll der erfolg überprüft werden. zur Überprüfung der reinigung werden i. d. r. bioindikatoren herangezogen, die die qualität der aufbereitung nach dem reinigungsprozess entweder visuell oder mittels proteinbestimmung belegen. da eine visuelle kontrolle erheblichen subjektiven einflüssen unterliegt, wird derzeit im arbeitskreis reinigungsmittel-testung der dg-kh an der optimierung quantitativer nachweisverfahren gearbeitet. dabei wird zurzeit die opa-und bca-proteinbestimmung favorisiert. verfahren zur Überprüfung der qualität der reinigung und desinfektion sind in der leitlinie veröffentlicht (dgkh, dgsv, aki, vah ). hände-, flächen-, instrumenten-und wäschedesinfektionsmittel die anforderungen ergeben sich aus den anwendungsgebieten, die entsprechend der normativen vorgaben des cen technical committee "chemische desinfektionsmittel und antiseptika" in der pren -"anwendung europäischer normen für chemische desinfektionsmittel und antiseptika" in den human-und veterinärmedizinischen bereich sowie den bereich lebensmittel, industrie, haushalt und öffentliche einrichtungen eingeteilt werden (cen a). (bansemir et al. ; gebel et al. ) , levurozid und begrenzt viruzid sein. sofern keine anschließende sterilisation erfolgt müssen sie zusätzlich fungizid und viruzid wirksam sein. ferner sollen instrumentendesinfektionsmittel für den benutzer ungiftig sein und empfindliche bestandteile der instrumente nicht beschädigen. wäschedesinfektionsmittel: das erforderliche wirkspektrum zur wäschedesinfektion muss bakterien, ggf. einschließlich mykobakterien, dermatophyten, sprosspilze und viren (begrenzt viruzid) umfassen. bei wahrscheinlicher oder bekannter kontamination durch besonders resistente krankheitserreger ist die erregergezielte auswahl zu beachten (rki a). materialien, die nicht gewaschen werden können, müssen mit wasserdampf, formaldehyddampf oder mittels chemischer desinfektion/reinigung desinfiziert werden. nach den deutschen regularien (rki a , hvbg ) wird die wäsche in gruppen unterteilt: • extrem gefährliche infektiöse wäsche z. b. von patienten, die an pocken oder hämorrhagischem fieber leiden. sie muss innerhalb der stationen desinfiziert und darf erst danach zusammen mit der potenziell infektiösen wäsche gewaschen werden. • infektiöse wäsche stammt von infektionsstationen, mikrobiologischen laboratorien und aus der pathologie und muss mit methoden und verfahren gemäß der rki-liste (rki ) desinfiziert werden. textilien und waschwasser müssen vor dem ersten ablassen des wassers desinfiziert werden (alexander et al. ; rki a in der vahliste sind verfahren für die routinemäßige und prophylaktische desinfektion zur verhütung von infektionen im krankenhaus, in der ärztlichen und zahnärztlichen praxis, in öffentlichen bereichen (kindertagesstätten, schulen, sportstätten usw.) sowie anderen bereichen, in denen infektionen übertragen werden können, zusammengefasst. für die aufnahme sind gutachten gemäß den standardmethoden der dghm zur prüfung chemischer desinfektionsmittel (› tab. . ) und den entsprechenden anforderungen (gebel et al. , dghm das rki hat methoden für die flächen-und instrumentendesinfektion beschrieben peters und bräuniger ; peters, bräuniger und fischer ; rki rki , a eine reduktion der testorganismen um eine zehnerpotenz bedeutet, dass bei einer ausgangskonzentration von eine inaktivierung von testorganismen, bei jedoch nur eine inaktivierung von testorganismen erfolgt. wirkungsbeeinflussende faktoren: die wirksamkeit von desinfektionsmitteln wird von den krankheitserregern (kaulfers ; mcdonnell und russell ; russell et al. ; spicher und peters ) und deren menge, von umgebungsfaktoren (organische belastung wie blut, sputum usw., vorhandensein protektiver bzw. interagierender substanzen, temperatur, ph-wert, luftfeuchtigkeit; spicher und peters , von der einbettung in biofilme (exner, tuschewitzki und scharnagel , donlan , dem kontaminierten objekt und der anwendungsmethode beeinflusst (spicher grundsätzlich unterscheidet man zwischen physikalischen und chemischen desinfektionsverfahren. als physikalische verfahren werden filtration, hitze-, plasma-und strahleneinwirkung verwendet. bei der thermischen desinfektion muss in einer bestimmten einzelne wäschestücke können durch einlegen in formaldehydlösung für h ( , %) oder h ( , %) desinfiziert werden. formaldehydabspaltende substanzen, wie paraformaldehyd, hexamethylentetramin und hexaminiumsalze, werden wegen ihrer unsicheren wirkung nicht für desinfektionszwecke empfohlen. formaldehyd wird ferner zur konservierung von immunseren und kosmetika sowie in endkonzentrationen von , - , % zur virus-und toxininaktivierung bei der impfstoffherstellung eingesetzt. der mak-wert wird derzeit bei , ml/m angesetzt. in den vergangenen jahren wurden aus tierversuchen mit hohen formaldehydkonzentrationen in der atemluft kanzerogene eigenschaften bekannt, was warnungen vor seinem gebrauch -auch als desinfektionsmittel -nach sich zog (› kap. . . ) . formaldehyd ist ein hinsichtlich seiner umfassenden wirksamkeit und deren nur unbedeutender beeinflussung durch organische belastungen sowie seiner wirkung in der gasphase zumindest in infektiologischen risikosituationen nach wie vor ein bewährter desinfektionswirkstoff. formaldehydbasierte flächendesinfektionsmittel verlieren in gesundheitseinrichtungen vor allem aufgrund der neueinstufung von formaldehyd durch die iarc, wegen der wenig anwenderfreundlichen eigenschaften und des neurotoxischen langzeitrisikos, z. b. in form des sick-building-syndroms, sowie aufgrund geeigneter alternativen zunehmend an bedeutung (schwebke et al., ) . in besonderen situationen und im zusammenhang mit außergewöhnlichen infektionskrankheiten kann im rahmen behördlicher desinfektionsmaßnahmen eine desinfektion mit formaldehyd bzw. formaldehydhaltigen desinfektionsmitteln erforderlich sein. hierbei ist durch arbeitsschutz-und organisatorische maßnahmen zu gewährleisten, dass der grenzwert eingehalten und personal sowie dritte nicht gefährdet werden (schwebke et al., ) . • formaldehyd ist ein starkes allergen und soll deshalb in konzentrationen ≥ , % nicht an der haut angewandt werden. • wegen der toxischen risiken, der lokalen reizwirkung und der verfügbarkeit von alternativen ist der einsatz von formaldehyd zur routinemäßigen flächendesinfektion nicht mehr zu empfehlen. das gilt auch für den rettungsdienst. glutaral (glutaraldehyd) wirkt besser sporozid als formaldehyd und wird deshalb in der instrumentendesinfektion eingesetzt. bei alkalischem ph ( , - , ) ist seine aktivität am höchsten, seine stabilität aber schlechter (zerfall innerhalb von wochen). die "sterilisation" von thermolabilen geräten (z. b. endoskopen) durch einlegen in eine glutarallösung ist ein unsicheres verfahren, weil nicht alle innenflächen sicher erreicht werden und das anschließend nötige abspülen mit sterilem wasser ein kontaminationsrisiko birgt. glutaral wird auch zur flächendesinfektion eingesetzt, was allerdings häufig zur geruchsbelästigung führt. für bernsteinsäuredialdehyd -zumindest in kombination mit formaldehyd und tensiden -wurde zusätzlich eine viruzide wirkung gegen hbv nachgewiesen. damit ist dieses präparat für die instrumentendesinfektion prädestiniert. glyoxal wird in desinfektionsmitteln nur als wirkungsverstärkender zusatz verwendet. oberflächenaktive stoffe (tenside) senken durch anreicherung an den grenzflächen zwischen zwei medien die grenzflächenspannung. manche dieser netzmittel sind auch antimikrobiell wirksam, sodass sie als "desinfizierende waschmittel" verwendet werden können. tenside lassen sich nach ihrem aufbau in gruppen einteilen: anionische, kationische, amphotere und nicht ionogene tenside (› tab. . ). antimikrobiell wirksam sind vor allem die kationenaktiven und amphoteren substanzen. quaternäre verbindungen (quats): sie sind durch eine positiv geladene hydrophile gruppe gekennzeichnet, die als ammonium-, sulfonium-, phosphonium-, iodonium-oder arsonium-gruppe vorhanden sein kann. am wichtigsten sind die quaternären ammoniumverbindungen wie benzalkoniumchlorid, cetylpyridiniumchlorid und didecyldimethylammoniumchlorid. die antimikrobielle wirkung dieser substanzen tritt schon in sehr niedrigen konzentrationen auf. sie ist zunächst wachstumshemmend (mikrobiostatisch), bei längerer einwirkzeit oder höheren konzentrationen mikrobiozid. die meisten grampositiven bakterien werden schon durch konzentrationen von - mg/l, gramnegative erst durch mindestens mg/l oder wie manche pseudomonas oder enterobacteriaceae spp. erst durch noch viel höhere konzentrationen abgetötet. bei diesen kann es sogar vorkommen, dass sie sich in der gebrauchsverdünnung vermehren. amphotenside vereinen elektropositive und -negative gruppen in einem molekül. je nach ph-wert der lösung verhalten sie sich als (negativ geladene) anionische (bei ph ) oder (positiv geladene) kationische tenside (bei ph < ). dazwischen sind sie elektrochemisch ausgeglichen. sie weisen den quaternären ammoniumbasen vergleichbare eigenschaften auf, wirken jedoch im gegensatz zu diesen gegen mykobakterien und sind weniger leicht durch eiweiß zu inaktivieren. wegen ihrer guten hautverträglichkeit wären sie als waschende händedesinfektionsmittel prädestiniert, sind aber für die anforderungen im medizinischen bereich zu wenig wirksam. in der lebensmittel-und getränkeindustrie werden sie vielfach eingesetzt. es existieren auch flächendesinfektionsmittel auf basis amphoterer substanzen. die halogene fluor (f), chlor (c), brom (br) und iod (i) sind mikrobiozid hoch wirksam. in der medizin werden nur cl und i zu desinfektionszwecken verwendet. hervorgerufenen oxidationsvorgänge bedingen neben mikrobioziden effekten auch das ausbleichen von farbstoffen. für die mikrobiozide wirkung, die unter geeigneten bedingungen das gesamte spektrum der viren und mikroorganismen einschließt, werden mehrere mechanismen verantwortlich gemacht: freisetzung von naszierendem sauerstoff, verbindung des chlors mit imino-und aminogruppen von im zytoplasma enthaltenen stoffen zu toxischen chloraminen, bildung unterchloriger säure, die ihrerseits oxidierend und chlorierend wirkt. in wässriger lösung ist hauptsächlich unterchlorige säure für die mikrobiozide wirkung verantwortlich. im schwach sauren bereich tritt der desinfektionseffekt wesentlich rascher ein als im alkalischen. eine temperaturerhöhung führt wie bei den meisten desinfektionsmitteln zu einer steigerung der desinfektionswirkung. organische substanzen beeinträchtigen die wirkung von chlor erheblich (chlorzehrung), sulfide, thiosulfat und eisensalze können sie völlig aufheben. chlor wird für die desinfektion gasförmig als cl oder als chlordioxid (clo ), aber auch in form von chlorabspaltenden verbindungen angewandt. die wichtigsten dieser verbindungen sind salze der unterchlorigen säure (hypochlorite) und chloramine. aus anwendungstechnischen gründen werden chlor-und chlordioxidgas nur zur wasserdesinfektion verwendet. wegen der chlorzehrung können für chlorgas keine fixen dosierungsangaben gemacht werden, sondern es muss von der nach verbrauch durch organische substanz zurückbleibenden konzentration des "restchlors" (verfügbares freies chlors) ausgegangen werden, die meist in mg/l (ppm) angegeben wird. für trinkwasser soll sich diese konzentration nach halbstündiger einwirkung um , mg/l, für schwimmbadwasser um , - , mg/l und für abwässer um - mg/l bewegen. das anstelle von chlorgas vielfach verwendete chlordioxidgas wirkt stärker bakterizid, ist in seiner wirkung stabiler gegen veränderungen des ph-werts und führt bei anwesenheit von phenolen im trinkwasser, im gegensatz zu chlorgas, nicht zur bildung von haloformen und chloraminen sowie kaum zu geschmacklich und geruchlich unangenehmen chlorphenolen. chlorabspaltende substanzen werden außer zur wasserdesinfektion im kleinen maßstab auch zur desinfektion von wäsche, flächen, händen, ausscheidungen und früchten sowie vor allem im sanitär-und küchenbereich verwendet. zur immer noch manchmal beworbenen desinfektion von fütterungsutensilien für säuglinge sind chlorverbindungen nicht zu empfehlen. mit physikalischen verfahren wie auskochen, dampfdesinfektion oder autoklavieren stehen sicherere desinfektionsverfahren für babyfläschchen und schnuller zur verfügung. hypochlorite führen zu einem rascheren eintritt des desinfektionseffekts als chloramine, zerfallen aber auch schneller. nicht stabilisierte hypochlorit-lösungen müssen deshalb sofort nach zubereitung verwendet werden! am häufigsten wird natriumhypochlo-rit (naocl), das in handelspräparaten mit stabilisatoren angeboten wird, verwendet. der billige chlorkalk, eine mischung aus calciumhypochlorit, -chlorid und -hydroxid, wird meist in krisenzeiten zur trinkwasser-und wischdesinfektion gebraucht. chloramine können als anorganische oder organische substanzen vorliegen. sie spalten chlor langsam ab, wodurch die wirkung zwar protrahiert eintritt, aber länger anhält. zu nennen ist vor allem das als "chloramin t" eingesetzte tosylchloramidnatrium. andere chlorabspalter sind z. b. di-und die antimikrobielle ausstattung von gegenständen des täglichen bedarfs und zunehmend auch im gesundheitsbereich mit metallen in nanokristalliner form hat weltweit in den letzten jahren ein starkes, teils kritikloses ausmaß erlebt. wenn auch je nach eingesetzter technologie und chemisch-physikalischen möglichkeiten der beteiligten komponenten (material, wirkstoff, imprägnierungsverfahren) eine wirksamkeit von objekten durch beschichtung oder imprägnierung mit antimikrobiellen stoffen gegen bestimmte mikroorganismenspezies erzielt werden kann, ist die bezeichnung "antimikrobiell" weder mit einer spezifischen infektionsprävention verknüpft, noch liegen ihr einheitliche kriterien zugrunde. jedes als "antimikrobiell" gekennzeichnete produkt muss neben dem nachweis der antimikrobiellen wirkung auch unter praxisrelevanten bedingungen einen belegten oder zu erwartenden vorteil im sinne der infektionsprävention für den einzelnen und das allgemeinwohl vorweisen können. der nutzen der antimikrobiellen imprägnierung oder beschichtung für den jeweils vorgesehenen anwendungsbereich muss kritisch gegen mögliche risiken und unerwünschte wirkungen für mensch und umwelt abgewogen werden. vor allem ist zu berücksichtigen, ob die wirkung mit üblichen hygienischen maßnahmen (reinigung, desinfektion) wirksamer und ungefährlicher erreicht werden kann . unter diesem aspekt ist auch die aktuelle bewerbung von kupferoberflächen in medizinischen bereichen zu betrachten. metallsalze (silber-und manche zinnsalze) wirken mikrobiozid, quecksilber-und kupfersalze vorwiegend mikrobiostatisch. silbersalze sind, nur bei unsachgemäßer anwendung (gefahr der argyrose) toxisch, können aber in hoher konzentration zu verätzungen führen. sie werden außer zur wasserdesinfektion heute nur noch in geringem ausmaß zur antiseptik verwendet (› kap. . ) . nanotechnologische silberapplikationen finden sich zunehmend als mikrobiostatische ausrüstung von kleidung und gebrauchsgegenständen, aber auch von blutgefäß-und hohlraumkathetern. quecksilber und seine anorganischen verbindungen sind stark toxisch, seine organischen verbindungen hingegen sind weniger giftig und besser hautverträglich. ihre verwendung als desinfekti-onsmittel ist obsolet, weil sie fast nur mikrobiostatisch wirken und keine sichere abtötung gegeben ist. mit organischen zinnverbindungen soll in kombination mit rasch wirkenden stoffen ein desinfektionseffekt mit lang anhaltender nachwirkung erzielbar sein. sie finden z. b. als tributylzinnbenzoat in präparaten für die flächen-und wäschedesinfektion anwendung, wobei aber toxikologische risiken nicht ausgeschlossen sind. neben den halogenen existieren einige stoffe, deren mikrobiozide wirkung ebenfalls auf oxidationsvorgänge zurückzuführen ist. es handelt sich dabei um sauerstoffreiche und leicht sauerstoff freisetzende verbindungen wie ozon, anorganische und organische peroxide sowie persäuren. das für den respirationstrakt giftige gas ist noch in verdünnungen von - an seinem charakteristischen geruch erkennbar. in wasser und bei hoher relativer luftfeuchtigkeit zerfällt es rasch. in wässrigem milieu umfasst das wirkspektrum bei anwendungskonzentrationen von maximal mg/l sämtliche formen von mikroorganismen. trockene ozon-luft-gemische haben hingegen keinen mikrobioziden effekt. wie die halogene wird auch ozon durch zahlreiche organische und anorganische verbindungen verbraucht (ozonzehrung). unter lichteinwirkung zerfällt es rascher als im dunkeln. bei niedrigen temperaturen ist sein mikrobiozider effekt besser als bei höheren. die wichtigste aussage der prüfung eines desinfektionsverfahrens ist zweifellos die über seine wirksamkeit. zur vollständigen charakterisierung eines desinfektionsverfahrens gehören allerdings auch die untersuchung und beschreibung toxikologischer, allergologischer und sicherheitstechnischer momente sowie sein einfluss auf die qualität des desinfektionsguts und anderen materials. nachfolgend wird nur auf die mikrobiologische prüfung eingegangen. prüfungen von desinfektionsverfahren werden als "typprüfungen" vor ihrer allgemeinen verwendung oder als "praxisprüfung" während und am ort der praktischen anwendung durchgeführt. in den verschiedenen ländern existieren unterschiedliche, meist von den jeweiligen fachgesellschaften für hygiene und mikrobiologie empfohlene prüfanordnungen. desinfektionsverfahren, für die durch gutachten belegbar ist, dass sie den jeweiligen anforderungen genügen, können in die "liste der geprüften und anerkannten desinfektionsverfahren" der jeweiligen körperschaft aufgenommen werden und/oder erhalten ein zertifikat (› tab. . • nachweis großer mikrobenmengen auf essgeschirr, instrumenten oder behältern, die mit schlecht reinigenden (kontamination durch schmutzige waschflotte!) und mangelhaft desinfizierenden waschmaschinen gewaschen wurden. mikrobiologische kulturen eignen sich nur bedingt für prüfungen, die der anwender selbst und ohne zuhilfenahme von fachleuten durchführt. deshalb ist es äußerst wichtig, dass der anwender seine desinfektionsverfahren mit anderen methoden regelmäßig kontrolliert (s. validierung). die von den fachgesellschaften für hygiene und mikrobiologie oder von regulationsbehörden herausgegebenen listen (› tab. . ) über gutachterlich geprüfte und für geeignet befundene verfahren (präparate mit anwendungsempfehlung) geben dem anwender eine gute orientierungshilfe für die verfahrensauswahl im krankenhaus. die empfehlungen der entsprechenden liste des rki (rki ) orientieren sich an den erschwerten bedingungen der kommunalen seuchenbekämpfung. bei der infektionsübertragung spielen die hände eine doppelte rolle: • sie dienen mikroorganismen als vehikel, indem sie mikrobielle kontaminationen aufnehmen und an anderer stelle deponieren. • sie fungieren als infektionsquelle, wenn sich erreger in den oberen schichten der haut oder auch in infizierten weichgewebeläsionen vermehren und von dort an die kontaktstelle freigesetzt werden. besondere bedeutung kommt den unmittelbaren kontaktflächen zu (bettwäsche, holme im griffbereich). eine manuell durchgeführte exakte reinigung und wischdesinfektion des bettgestells mag den hygienischen anforderungen genügen. die von manchen als unnötig aufwendig befundenen maschinellen verfahren der bettenaufbereitung erbringen, sofern sie richtig betrieben werden, gleich bleibend gute ergebnisse und unterstützen die anliegen der qualitätssicherung. als desinfektionsprinzip werden heißwasser oder wasserdampf, evtl. in kombination mit chemischen desinfektionsmitteln, eingesetzt. für die dampfdesinfektion haben sich insbesondere das dampfströmungsverfahren und das vakuum-dampf-vakuum-verfahren (vdv-verfahren) bewährt und werden vom rki anerkannt (rki ). es handelt sich um folgende gegenstände: operationsinstrumente, anästhesiezubehör, endoskope, ess-und trinkgeräte, fütterungsutensilien, auffangbehälter für sekrete, drainageflüssigkeiten, stuhl und urin; atemgas-waschflaschen, blumenvasen, irrigatoren sowie gebrauchsgegenstände der patienten. zur mehrmaligen verwendung bestimmte gegenstände müssen nach jedem gebrauch (gereinigt und) desinfiziert werden. zur einmalverwendung vorgesehene gegenstände behindern durch ihre konstruktion oft eine wirksame reinigung und desinfektion oder/und nehmen durch aufbereitung vielleicht schaden. sie dürfen deshalb nur im ausnahmefall und nur unter streng definierten bedingungen (ausschluss unerwünschter wirkungen, definiertes validiertes aufbereitungsverfahren, zertifiziertes qualitätsmanagement, › kap. . ) aufbereitet werden! aus produkthaftungsgründen dürfen nur gegenstände aufbereitet werden, für die geeignete aufbereitungsverfahren definiert sind. dabei ist auch der schutz des personals vor infektionen zu bedenken. die maschinelle reinigung und desinfektion ist manuellen verfahren grundsätzlich vorzuziehen. das hat zwei wesentliche gründe: maschinen mit kombinierten reinigungs-desinfektions-verfahren reinigen undesinfizierte güter ohne personen zu gefährden. das ist wichtig, weil nur nach guter vorreinigung ein gleich bleibend guter desinfektionseffekt mit vertretbarem aufwand sichergestellt werden kann. (verfahren der kommunalen seuchenbekämpfung, die aus epidemiologischen gründen als ersten schritt grundsätzlich eine desinfektion erfordern, bleiben hier außer betracht.) ferner können thermische und chemothermische desinfektionsverfahren wirkungsvoll in maschinelle reinigungsverfahren integriert werden. ausschlaggebend für die desinfektionswirkung solcher maschinen ist die güte ihres reinigungssystems. das gilt insbesondere, wenn der zu beseitigende schmutz stark erregerhaltig ist (z. b. stuhl). in solchen fällen können schon kleinste schmutzreste ein versagen der anschließenden desinfektion zur folge haben. die in der praxis erzielte reinigungswirkung hängt nicht nur von konstruktiven details der maschine ab, sondern auch von ihrer richtigen beschickung (spülgerechte lagerung der güter, keine Überladung der maschine, keine behinderung der beweglichen teile des reinigungssystems, keine spülschatten) und ihrer ordnungsgemäßen wartung (reinigung von düsen, schmutzfangsieben usw.) ab. hinweise auf konstruktive details der maschinen und auf die verfahren zur prüfung der reinigungswirkung finden sich z. b. in koller, a und koller, b auch zu hohe temperaturen (> °c) in der reinigungsphase beeinträchtigen das reinigungsergebnis bei organischen verunreinigungen durch koagulation nativer proteine. die in den programmablauf der maschinen integrierten thermischen desinfektionsverfahren bringen meist heißwasser (z. b. desinfizierte güter sollen grundsätzlich möglichst rasch getrocknet und trocken gelagert werden. medizinisch-technische geräte sind gesondert zu besprechen, weil sie meist neben teilen, die mit patienten in direkten oder indirekten kontakt kommen, feinmechanische, optische oder elektronische elemente besitzen, die durch desinfektionsmaßnahmen beschädigt werden können. grundsätzlich sind medizinisch-techni-sche geräte so aufzubereiten, dass sie für die anwendung am nächsten patienten sicher sind. voraussetzung dafür ist eine bauart, die wirksame aufbereitungsverfahren zulässt. viel zu oft blieb dieses gebot in der vergangenheit unbeachtet. oft wurden geräte angeschafft, die eine wirksame und sichere desinfektion nicht zulassen. im folgenden sind wichtige hygienische grunderfordernisse an bauart und beschaffenheit medizinisch-technischer geräte aufgezählt: • reinigbarkeit: teile des geräts, die mit dem patienten oder seinen ausscheidungen in kontakt treten, müssen einfach demontierbar und maschinell zu reinigen sein. die im folgenden angeführten wirkstoffe finden allein oder in kombination in vielen handelsüblichen flächendesinfektionsmitteln anwendung: glutaral, formaldehyd und glyoxal, meist in kombination untereinander und gemeinsam mit tensidischen wirkstoffen. diese produktgruppe weist ein breites wirkspektrum ohne wesentliche lücken auf und ist, insbesondere bei ausreichendem formaldehydanteil auch für situationen mit stärkerer organischer belastung des desinfektionsguts geeignet. wichtige nachteile sind schleimhautreizungen bei großflächigem einsatz und schlechter belüftung sowie hautreizungen bei kontakt mit der gebrauchslösung. die anwendung muss daher in richtiger dosierung erfolgen und nicht in heißem oder warmem wasser (geruchsbelästigung) oder ohne handschuhe. phenolderivate wirken verhältnismäßig rasch, werden durch organische begleitstoffe nur mäßig gehemmt und weisen ein breites wirkspektrum auf. gegen enteroviren ist ihre wirkung nur gering. die kombination mit waschaktiven substanzen ist möglich. wegen der gefahr einer hyperbilirubinämie bei neugeborenen und frühgeborenen werden sie in neonatologischen abteilungen nicht eingesetzt. amphotenside, quats und amine haben eine gute reinigungswirkung und sind wenig aggressiv, besitzen aber ein eingeschränktes wirkspektrum (schwächen gegenüber pilzen, mykobakterien und viren) und einen deutlichen eiweißfehler. in kombination mit guten reinigungsmethoden und bei langen einwirkzeiten ergibt sich eine akzeptable desinfektionswirkung. im krankenhaus kann ihr einsatz nur in niedrigrisikobereichen und nur im zusammenhang mit optimalen reinigungsmethoden akzeptiert werden. natriumhypochlorit und organische chlorabspalter (chloramine, di-und trichlorisocyanurate usw.) wirken rasch und besitzen ein breites wirkspektrum mit guter viruzider wirkung. wegen der starken chlorzehrung durch organische substanzen dürfen sie nur auf reinen oder vorgereinigten flächen verwendet werden. kombiniert mit scheuermitteln eignen sie sich gut zur reinigung und desinfektion im sanitärbereich. ethanol und die beiden propanole sind in konzentrationen wie zur händedesinfektion auch im wischverfahren rasch wirksame flächendesinfektionsmittel mit breitem wirkspektrum bei geringer beeinträchtigung durch organische verschmutzungen. von einer großflächigen aufbringung oder anwendung im sprühverfahren ist wegen der explosions-und brandgefahr abzuraten. peressigsäure und perameisensäure eignen sich zur anwendung an korrosionsbeständigen oberflächen (insbesondere kunststoffen) und finden in situationen einsatz, wo eine sporozide wirkung gewünscht wird (z. b. im rahmen der schutzisolierung bei knochenmarktransplantation). alternativ kommen organische peroxide in betracht. die meisten flächendesinfektionsmittel werden als konzentrate geliefert und sind in gebrauchsverdünnungen, häufig von , %, anzuwenden. in der praxis macht die richtige einstellung der desinfektionslösung oft schwierigkeiten. bei manueller herstellung müssen vom reinigungspersonal dosierhilfen, z. b. messbecher mit deutlicher markierung, dosierpumpen, die auf den konzentratbehälter aufgeschraubt werden, oder beutel und tuben, die eine auf einen eimer wasser abgestimmte portion enthalten, verwendet werden. nicht akzeptabel ist das zugeben eines "schusses" des konzentrats nach gutdünken. vorsicht ist auch bei der herstellung von konzentrationen, die nur einen oder zwei hübe der dosierpumpe benötigen, geboten, da viele dieser einfachen handpumpen erst ab dem dritten hub richtig dosieren! vielfach werden zur herstellung der gebrauchslösung des flächendesinfektionsmittels automatische zumischanlagen verwendet, die jedoch häufig nicht einwandfrei funktionieren. bei manchen anlagen hängt die konzentration der abgegebenen lösung vom wasserdruck ab oder wird übersehen, dass der konzentratbehälter leer oder die zumischdüse verstopft ist. in perioden ohne anwesenheit von desinfektionsmittel kann es zur ansiedlung von bakterien, vor allem pseudomonas-arten, im leitungssystem der zumischanlage kommen (biofilme). diese mikroben können eine erhöhte chemoresistenz entwickeln. vor allem große zentrale anlagen, die ein ganzes haus versorgen, neigen zu solchen problemen und sind daher nicht zu empfehlen. dezentrale zumischanlagen sind besser kontrollierbar und können dort, wo ein flächendesinfektionsmittel häufig verwendet werden muss, sinnvoll sein. dosieranlagen sollen den technischen anforderungen entsprechen, wie sie z. b. in deutschland (bundesanstalt für materialprüfung und bundesgesundheitsamt ) und in Österreich (friebes und dosch ) in richtlinien festgelegt sind, und müssen regelmäßig kontrolliert werden. wartung der reinigungs-und desinfektionsutensilien › kapitel . . wände, decken und einrichtungsgegenstände in medizinisch genutzten bereichen des krankenhauses müssen abwaschbar sein, um sie reinigen und bei bedarf desinfizieren zu können. wände sollen routinemäßig bis in greifhöhe gereinigt werden. eine desinfektion wird nur nach kontamination (z. b. verspritzen infektiöser sekrete) oder im rahmen der sanierung eines raums nach entlassung eines infektiösen patienten (wischdesinfektion) für nötig erachtet. patientennahe arbeitsflächen, auf denen auch saubere güter und behandlungsbehelfe abgelegt werden, sollen routinemäßig wischdesinfiziert werden. für häufig berührte gegenstände (türklinken, telefonhörer usw.) ist das zumindest in epidemischen situationen ebenfalls angezeigt. die desinfektion von wänden, decken und einrichtungsgegenständen kann die viel wichtigere nichtkontamination (berührungsfreie techniken) und die händehygiene nicht ersetzen, sondern nur ergänzen. die dekontamination der luft soll die entstehung aerogener infektionen verhüten helfen. unter aerogener infektion ist hier nicht die als tröpfcheninfektion bekannte Übertragungsart zu verstehen, bei der z. b. husten-oder sprechtröpfchen der infektionsquelle auf das infektionsziel geschleudert werden. gemeint ist die suspension und translokation von mikroorganismen durch luft. mit wenigen ausnahmen (› tab. . ) spielt dieser infektionsweg im krankenhaus gegenüber den anderen Übertragungsmöglichkeiten eine untergeordnete rolle. sofern aerogene infektionen eine rolle spielen und die streuung der erreger nicht schon an der infektionsquelle blockiert werden kann (wie bei klimaanlagen, raumluftbefeuchtern oder beatmungsgeräten), sollte die blockierung des aerogenen Übertragungswegs einen positiven effekt zeitigen. das lässt sich entweder durch filtra tion der luft oder durch physikalische oder chemische inaktivie rung der luftgetragenen mikroorganismen erreichen. schon ausgiebiges lüften eines raums kann eine keimzahlverminderung von bis zu % bewirken. verlässlicher und mit einem besser kalkulierbaren wirkungsgrad werden rlta eingesetzt, z. b. in op-einheiten. eine früher oft übliche form der luftdekontamination ist die durch uvstrahlen. diese methode ist nur unter streng definierten, standardisierten bedingungen zuverlässig und auf sehr umschriebene anwendungen beschränkt (z. b. entkeimung von werkbänken und arbeitsboxen für infektiöse oder infektionsriskante tätigkeiten). eine chemische luftdekontamination während des aufenthalts von personen im raum durch verdampfen oder versprühen von glykolen oder anderen desinfektionsmitteln ist abgesehen vom umstrittenen mikrobioziden effekt solcher maßnahmen aus grundsätzlichen Überlegungen abzulehnen. das risiko einer gesundheitsschädigung durch chemisierte atemluft steht in keinem verhältnis zum zu erwartenden nutzen. die formaldehyd-wasserdampf-raumdesinfektion im rahmen der schlussdesinfektion (› kap. . . ) ist nur in sonderfällen indiziert und keinesfalls routinemäßig anzuwenden. zunächst ist es nötig, schwerpunkte festzulegen. die verfügbaren mittel und kräfte müssen auf die wichtigen infektionsüberträger konzentriert werden. anhaltspunkte für kriterien zur beurteilung der gefährlichkeit bestimmter infektionsüberträger und beispiele finden sich in › tab. . . die desinfektion von händen, instrumenten und ausscheidungsbehältern hat einen hohen stellenwert, die von wänden oder fußböden einen niedrigen. zusätzlich zu desinfektionsmaßnahmen muss in der praxis entschieden werden, ob eine sterilisation nötig ist (bei kontakt mit gewebe, blut oder sterilen körperhöhlen) oder ob einmalware zu bevorzugen ist. bei der auswahl eines desinfektionsverfahrens werden die weichen für den späteren erfolg oder misserfolg gestellt. qualität und kapazität eines verfahrens, seine kompatibilität mit bestehenden systemen, verfügbarkeit und qualität eines kundendienstes, verfügbarkeit des notwendigen personals und verfügbarkeit der nötigen betriebsmittel sind einige faktoren, die vor der anschaffung geklärt sein müssen. jedes desinfektionsverfahren ist nur so gut wie seine gebrauchsan weisung. die wichtigsten bedienungs-, kontroll-und schutzanweisungen müssen dem anwender jederzeit in kurzer, verständlicher und leicht lesbarer form zur verfügung stehen. komplizierte maschinelle verfahren erfordern neben einer schriftlichen betriebsanleitung eine persönliche einführung oder einen eigenen ausbildungskurs für das bedienungspersonal. mikrobiologische kontrollen besitzen zwar eine hohe aussagekraft, sind aber meist zu aufwendig und beschränken sich daher in der regel auf die periodischen behördlichen kontrollen von desin- • hygienische anforderungen an räumliche gestaltung und arbeitsabläufe lassen sich leichter realisieren. • leistungsfähige rdg ersetzen eine vielzahl dezentral laufender kleingeräte und werden durch einen begrenzten, gut geschulten personalstab richtig bedient. • wartung der geräte und kontrolle der arbeitsabläufe sind wesentlich besser überschaubar. • der bedarf an spezifisch geschultem personal ist wesentlich kleiner als bei dezentraler ausführung. . ) . bei der von flächen ausgehenden risikobewertung ist zu berücksichtigen, dass sich die zur auslösung einer infektion erforderliche infektionsdosis erregerabhängig z. t. deutlich unterscheidet (› tab. . ). grundsätzlich ist zu berücksichtigen, dass der stel-lenwert der flächendesinfektion zur infektionsprävention mit zunehmender distanz zum patienten abnimmt. folgendes beispiel unterstreicht den beitrag der flächendesinfektion zur aseptik. in einem eingriffsraum konnte durch desinfektion aller flächen einschließlich des inventars nach dem letzten eingriff und anschließende abhängung nicht aus dem raum herausnehmbarer geräte und des inventars mit sterilen op-tüchern die raumluftqualität von reinraumklasse c zu reinraumklasse b verbessert werden (below et al. ). bei mutmaßlicher oder sichtbarer flächenkontamination mit blut und weiteren sekreten und exkreten ist die sog. gezielte oder anlassbezogene desinfektion durchzuführen. hierbei ist die chemoresistenz des mutmaßlichen erregers zu beachten (z. b. m. tuberculosis, c.-difficile-sporen, noroviren, ggf. prionen . ) . bei der entscheidung, ob routinemäßig eine reinigung oder eine desinfizierende reinigung durchgeführt werden soll, müssen auch praktikabilität und sichere durchführbarkeit berücksichtigt werden. in op-einheiten werden zwischen zwei operationen die flächen im arbeitsbereich um den op-tisch, die verkehrswege im op-raum und alle kontaktflächen desinfiziert. die vom vah angegebene möglichkeit, dass mit der vorbereitung der nächsten op begonnen werden kann, sobald die flächen luftgetrocknet sind, d. h. u. u. vor ablauf der vom hersteller angegebenen einwirkungszeit, ist aufgrund der prüfergebnisse im vier-felder-test kritisch zu sehen. in diesem praxistest wird bei einsatz der konzentrationen für lange einwirkungszeiten ≥ min die wirksamkeit z. t . erst nach min oder min erreicht -da sind die flächen aber schon (lange) trocken. daher sollte bei gewählten einwirkzeiten > min mit der vorbereitung der nächsten op die einwirkzeit und nicht nur die trocknung abgewartet werden, solange keine neuen erkenntnisse ein anderes vorgehen ermöglichen. sofern die wände nicht sichtbar kontaminiert sind, entbehrt die noch anzutreffende empfehlung, nach beendigung des op-programms im op-saal eine wischdesinfektion der wände bis zur höhe von m durchzuführen, ihrer experimentellen oder epidemiologischen grundlage. abhängig von der raumlufttechnik, dem op-spektrum und der experimentell ermittelbaren dynamik der mikrobiellen belastung der wände kann der krankenhaushygieniker den rhythmus festlegen (z. b. monatlich). bei nachgewiesenermaßen funktionierender verdrängungslüftung (raumklasse ia) ist die gezielte desinfektion als ausreichend anzusehen, d. h., es kann auf die fußbodenwischdesinfektion zwischen zwei eingriffen -allerdings nur in einem augen-op nachgewiesen und nur bei nicht septischem eingriff vertretbar -verzichtet werden (knochen et al. ). in op-einheiten/ eingriffsräumen sind umfang und rhythmus der desinfizierenden flächenreinigung im ergebnis des gemeinsamen risk assessments durch den jeweiligen fachvertreter und den krankenhaushygieniker festzulegen. flächen, auf denen aseptische arbeiten ausgeführt werden, sind grundsätzlich desinfizierend zu reinigen. in reinräumen (z. b. apotheke, herstellung von blutprodukten, hornhautbank, stammzellpräparation) sind die dort gültigen spezifischen vorschriften einzuhalten. in küchen und milchküchen gelten die vorgaben des lebensmittelrechts. bei erhöhter infektionsgefährdung entweder aufgrund reduzierter immunabwehr und/oder der hohen wahrscheinlichkeit fortwährender freisetzung kritischer erreger, insbesondere von mre (z. b. its, risikogruppe und immunsupprimierter) in die umgebung sowie bei sichtbarer kontamination sollte zur flächendesinfektion mindestens die konzentration des desinfektionsmittels für den -h-wert eingesetzt werden, damit die wahrscheinlichkeit der sicheren erfassung der auf den flächen unterschiedlich verteilten erreger steigt. als anlassbezogene schlussdesinfektion wird die gezielte desinfektion eines raums oder bereichs einschließlich der in ihm vorhandenen oberflächen und gegenstände nach erfolgter pflege oder behandlung eines infizierten bzw. mit hochkontagiösen erregern besiedelten patienten bezeichnet. durch organisation, auswahl der reinigungs-und desinfektionsmittel und -verfahren sowie die häufigkeit müssen im einvernehmen mit dem krankenhaushygieniker/der hfk im hygieneplan festgelegt werden. im alten-und pflegeheim gelten vom grundsatz her die gleichen anforderungen an die desinfizierende reinigung wie im patientenzimmer, wenn patienten mit erhöhter infektionsgefährdung behandelt, bei kolonisation z. b. mit mrsa saniert oder als ausscheider von infektionserregern versorgt werden. die desinfektion muss als prozess betrachtet werden. es sind standards für die reinigung und desinfektion zu erarbeiten, deren sachgerechte umsetzung durch sops, aus-, fort-und weiterbildung sowie durch geeignete auditsysteme sichergestellt wird (gebel et al . allgemeiner ablauf: reinigungswagen vor dem zu reinigenden zimmer seitlich abstellen und darauf achten, dass die wege frei bleiben. warnschild "rutschgefahr" im flur aufstellen. die reinigung eines zimmers beginnt grundsätzlich mit der müllentleerung, dann erfolgt die reinigung der oberflächen (zuerst zimmer, dann sanitärbereich), erst danach die reinigung des fußbodens. reini-gungstuch immer -fach falten; sobald eine seite verschmutzt ist, reinigungstuch wenden und nächste saubere seite verwenden grundsätzlich sind reinigungstätigkeiten von oben nach unten, von hinten nach vorn und von sauber zu schmutzig durchführen. oberflächenreinigung im patientenzimmer: abfallbeutel entleeren, verschließen und am reinigungswagen entsorgen. neuen beutel einsetzen, nicht in abfalleimer hineingreifen, abfall in den behältnissen nicht von hand eindrücken! mit vorgetränktem reinigungstuch folgende oberflächen reinigen: lichtleisten, fensterbank, tische, stühle, wandschmuck, abfalleimer außen, schalter, dosen, stromleisten, türgriffe, türen im griffbereich (desinfektion), fernseher, außenbereiche der schränke im griffbereich. falls waschbecken im patientenzimmer, mit andersfarbigem tuch reinigen. verwendete tücher sind nach jedem patientenzimmer abzuwerfen. oberflächenreinigung in der nasszelle: abfalleimer wie im patientenzimmer entsorgen. wc spülen, dann wc-reiniger in wc-becken, urinal und unter den spülrand spritzen und einwirken lassen, toilettenbürste in das wc-rohr stellen. die reinigung ist immer von oben nach unten durchzuführen. während der einwirkzeit mit reinigungstuch erst den spiegel, dann die ablage und danach waschbecken mit armatur und spritzbereich reinigen, danach alle sonstigen oberflächen, ggf. spiegel mit trockenem gelbem reinigungstuch nachpolieren, anschließend sitzhilfen und abfalleimer mit gelbem reinigungstuch reinigen. danach toilette gründlich nachbürsten und mit wasser nachspülen, dann mit andersfarbigem reinigungstuch wc-brille und becken außen sowie den spritzbereich um das becken reinigen. nach jedem sanitärraum reinigungstücher in das netz am reinigungswagen abwerfen. seife und papier auffüllen. in › tab. . ist ein muster eines leistungsverzeichnisses für die reinigung und desinfektion ausgewählter räume zusammengestellt, dass der konkreten infektionsgefährdung angepasst werden muss. desinfizierende raumverneblung: wenn sich im rahmen eines ausbruchmanagements herausstellt, dass nach der schlussdesinfektion die ursächlichen erreger noch nachweisbar sind, ist es durch raumverneblung mit wasserstoffperoxid (wpo) sinnvoll, die zeitspanne bis zum erreichen der sicheren flächendesinfektion zu überbrücken. da die qualitätsverbesserung der arbeit des reinigungsteams wochen in anspruch nehmen kann und im rahmen eines vre-ausbruchs die erreger trotz schlussdesinfektion an relevanten stellen im patientenzimmer nachweisbar waren, wurde die verneblung bis zur nachgewiesenen sicheren schlussdesinfektion durchgeführt. mit einführung der verneblung war ein kontinuierlicher rückgang der nosokomialen Übertragung von vre bis zur beendigung des ausbruchs nachweisbar (kramer et al. in vorb.) . voraussetzung für die einführung des verfahrens war dessen wirksamkeitsnachweis bei einwirkung auf mit a. brasiliensis kontaminierten prüfkörpern, die in einem versuchsraum wandständig und unter der decke platziert waren, sowie in räumen mit schimmelpilzbefall nach einem wasserschaden (koburger et al. die sichere aufbereitung ist erforderlich, weil wiederverwendbare tuchspender insbesondere bei einsatz oberflächenaktiver wirkstoffe kontaminiert waren (kampf et al. b ). die aufbereitung im rdg verhinderte ohne und mit zusatz chemischer reinigungsmittel die rekontamination der desinfektionsmittellösung, wenn eine temperatur zwischen - °c über mindestens min sichergestellt wurde. ebenso verhinderte die vorreinigung mit heißem wasser oder in form eines gründlichen reinigungsschritts mit nachfolgender wischdesinfektion mittels einmaltuch und sauerstoffabspalter die rekontamination (kampf et al. a ), müsste aber als prozess validiert werden. allerdings wurde die wirksamkeit der aufbereitung nicht nach sporenkontamination geprüft, die in praxi jedoch nicht auszuschließen ist. desinfektions-und reinigungsverfahren sowie die aufbereitung der benötigten utensilien sind regelmäßigen kontrollen zu unterziehen. die gewährleistung der qualitätsgerechten desinfizierenden flächenreinigung ist wegen der wachsenden bedeutung für die infektionsprävention ein dauerbrenner sowohl für die leitung des krankenhauses als auch für die patienten und deren besucher (carling, parry und von beheren ) . durch hygienisch-mikrobiologische untersuchungen sollte die wirksamkeit von reinigungs-und desinfektionsverfahren kontrolliert werden (krinko ) . auch wenn die ermittlung der mikrobiellen belastung trotz mangelnhafter standardisierung von methoden und bewertungskriterien (galvin et al. ) der goldstandard zur qualitätssicherung ist, eignen sich einfach durchführbare fluoreszenzmethoden zur qualitätskontrolle (blue et al. ; boyce et al. ; carling et al. ; luick et al. ; munoz-price et al. ). als quantitative, standardisierte mikrobiologische beprobungstechnik empfiehlt sich zukünftig die in der en angegebene methode. während eine sichtkontrolle nicht zielführend ist, ermöglichen audits mit detaillierten checklisten eine realistische bewertung (malik, cooper und griffith ) . häufigkeit und umfang der kontrollen werden vom krankenhaushygieniker in zusammenarbeit mit der hfk festgelegt (zu aussagewert, richtwerten und gesamtbeurteilung › kap. . . ; jülich et al. ; klein und deforest ; mahnel ; poshni ; von rheinbaben und kirschner in der praxis werden physikalische verfahren oft mit chemischen einflüssen kombiniert. am häufigsten sind chemothermische verfahren. anstelle thermischer einflüsse kann auch ultraschall oder uv-licht (in gegenwart photoinaktivierender substanzen) angewandt werden. selbst wenn bei den vertretern einer virusfamilie deutliche unterschiede in der resistenz gegenüber umwelteinflüssen und desinfektionswirkstoffen auftreten können und sogar innerhalb einer art unterschiede festgestellt wurden, ist es vertretbar, für jede virusfamilie eine zusammenfassende bewertung vorzunehmen. adenoviren ( peters, bräuninger und fischer ; rki b; ) wurden parvoviren v. a. wegen ihrer guten trockenstabilität aufgenommen. bei inaktivierungsversuchen an der fläche war parvovirus deutlich stabiler als polio-und adenovirus (eterpi, mcdonnell und thomas (thomssen et al. ). die meisten arten sind im ph-bereich - über viele tage stabil, nicht jedoch rhinoviren, die gegenüber ph-werten im sauren bereich empfindlich reagieren und bei ph in min inaktiviert werden. insbesondere polioviren und offensichtlich auch das hav sowie viele stämme der coxsackie-und echo-viren sind hydrophil. manche unter ihnen, z. b. echo-virus und , besitzen aber auch leicht lipophile eigenschaften und reagieren schwach mit lipiden. sie werden deshalb durch lipophile substanzen, v. a. durch längerkettige alkohole, inaktiviert. hydrophile picornaviren, insbesondere das poliovirus, sind stattdessen gegenüber kurzkettigen hydrophilen alkoholen empfindlich. innerhalb der picornaviren liegen die meisten experimentellen erfahrungen bei polioviren vor. in ihrer resistenz gegenüber desinfektionswirkstoffen ähneln sie den parvoviren, zeigen im gegensatz zu diesen aber keine erhöhte thermoresistenz und sind auch gegenüber austrocknen sehr empfindlich. da polioviren neben ihrer hohen desinfektionsmittelresistenz zusätzlich den vorteil einfacher handhabbarkeit bieten, findet man sie als prüfviren in vielen leitlinien und normen (en : ; rki ) . gegenüber methanol und ethanol sind polioviren sehr empfindlich. propan- -ol zeigt dagegen bei % v/v/ min keine wirksamkeit und eine exposition gegenüber propan- -ol führt unter den gleichen bedingungen selbst nach min zu keinem messbaren titerverlust. methanol verursacht bei % v/v/ min schon bei °c eine titerreduktion von mindestens zehnerpotenzen. für ethanol sind bei raumtemperatur und anwendungskonzentrationen zwischen und % einwirkungszeiten von - min notwendig, um eine titerreduktion von - zehnerpotenzen zu erzielen (van engelenburg et al. ) . auch hav gehört zu den picornavieren und zeigt eine hohe thermoresistenz und stabilität gegenüber desinfektionswirkstoffen. °c/ min werden nahezu verlustfrei toleriert, °c reichen auch während h nicht zur sicheren inaktivierung aus. , -prozentiges glutaral führt innerhalb von min zu einer reduktion von zehnerpotenzen. mit , -prozentiger lösung sind dafür min notwendig (passagot et al. ) . zur inaktivierung durch peressigsäure sind %/ min notwendig (rf > ). bei %/ min ist dagegen keine ausreichende wirksamkeit zu erwarten (rf , ). bei der auswahl von desinfektionsmitteln gegen picornaviren sollten nur mittel verwendet werden, deren wirksamkeit durch untersuchungen gegenüber poliovirus typ belegt wurde. zwar können bei den verschiedenen picornaviren unter gleichen experimentellen bedingungen unterschiede in anwendungskonzentration und/oder einwirkzeit festgestellt werden (sauerbrei et al., ) die wichtigste gruppe innerhalb der familie der reoviren (unbehüllt) sind die fäkal-oral übertragenen rotaviren. in der neonatologie und pädiatrie sind sie häufig ursache nosokomialer virusinfektionen, besitzen aber auch als erreger von reisediarrhöen und für alte menschen hohe bedeutung. rotaviren zeigen hohe trockenresistenz und sind im ph-bereich zwischen und stabil (lloyd-evans, springthorpe und sattar ). auch temperaturen von °c werden toleriert (baumeister ) . ihr komplexes kapsid macht rotaviren nicht nur gegen stark oxidierende desinfektionsmittel, sondern auch gegen lipidlösungsmittel, alkohole und alkoholische chlorhexidinlösungen sowie gegenüber phenolischen wirkstoffen empfindlich (vaughn, chen y-s und thomas ) . formaldehyd ist bei %/ min wirksam, -prozentiges v/v ethanol in s (tan und schnagel ) . propan- -ol, propan- -ol und butanol vermögen in -bis -prozentiger lösung bovines rotavirus selbst in gegenwart von stuhl in min um - zehnerpotenzen zu reduzieren (kurtz, lee und parsons ) . kurzkettige alkohole wirken aber insgesamt schlechter als längerkettige verbindungen. -prozentiges methanol ist unwirksam. ameisensäure inaktiviert rotavirus , -prozentig in min, propionsäure -bis -prozentig nach dieser einwirkzeit. essigsäure muss -prozentig für min angewendet werden. als prüfviren für den humanmedizinischen bereich hat das humane rotavirus (stamm wa) verwendung gefunden. sofern keine unter-suchungen mit reoviren/rotavirus selbst vorliegen, sollten wegen der klinischen bedeutung dieser viren bei der auswahl von desinfektionsmitteln nur viruzide mittel gewählt werden. retroviren (behüllt, lipidhaltig) stellen mit hiv- und hiv- die zurzeit wichtigsten humanpathogenen viren. zur familie zählen auch die humanen t-zell-leukämieviren. diese viren werden sexuell und durch blut-blut-kontakte übertragen und besitzen nur eine geringe umweltresistenz. das darf aber nicht dazu führen, die stabilität insbesondere in natürlichen begleitmaterialien zu unterschätzen, die unter geeigneten bedingungen mehrere wochen betragen kann. gegenüber desinfektionswirkstoffen sind keine besonderen resistenzen bekannt. trotzdem dürfen bei der behandlung viruskontaminierten materials nur neueste empfehlungen berücksichtigt werden. gerade aus der frühphase der hiv-pandemie existieren angaben, wie z. b. anwendung von -prozentigem, ja sogar -prozentigem ethanol, die nach heutigem wissen unter praxisbedingungen zu keiner sicheren inaktivierung führen! ebenso werden abhängig von der verwendung von zellfreiem oder zellgebundenem virus z. t. erhebliche unterschiede in der resistenz beschrieben (hanson et al. unkonventionelle erreger zeichnen sich durch äußerst hohe umwelt-und chemikalienresistenz aus. in der umwelt können sie über jahre persistieren. die üblichen desinfektionswirkstoffe und -verfahren wie alkohole, aldehyde, iod-und phenolhaltige präparate, beta-propiolacton, ethylenoxid und uv-oder radioaktive bestrahlung sind zur inaktivierung nicht geeignet oder zeigen nur eingeschränkte wirksamkeit (danner, ) . als sicheres verfahren gilt die dampfsterilisation im autoklaven bei °c ( h, bar) möglichst unter vorbehandlung von m naoh (riesner ). in den meisten fällen scheint das autoklavieren bei °c/ h geeignet zu sein, wenn das ausgangsmaterial nicht mit hoch erregerhaltigem material kontaminiert ist (taylor et al. ). auch die behandlung mit m naoh über h, , -bis -prozentigem natriumhypochlorit über h, kochen in -prozentigem natriumdodecylsulfat (sds) für mindestens min sowie - m guanidiumisothiocyanat ( m/ h; m/ h; m/ min) zerstören die infektiosität. bei hohem oder erhöhtem cjd-bzw. vcjd-risiko soll zuerst in dieser form desinfiziert, dann maschinell aufbereitet und abschließend bei °c h sterilisiert werden. es gibt allerdings auch alkalische reiniger, die in der lage sind, prionen gegenüber einem dampfsterilisationsverfahren zu sensibilisieren (destabilisieren), sodass eine gute vorreinigung mit diesen nicht nur eine dekontaminationswirkung, sondern auch eine reduktion der kontaktzeit von autoklavierungsverfahren ermöglicht (› kap. . ). ausgangspunkt für die in-vitro-untersuchung von präparaten auf viruswirksamkeit ist der quantitative suspensionsversuch. dieser wird nach der aktualisierten leitlinie der dvv und des rki (deutschen vereinigung zur bekämpfung der viruskrankheiten/rki, ) oder nach der europäischen norm en ( ) neben seinem bakteriziden wirkspektrum ist ethanol innerhalb von - s konzentrationsabhängig viruzid wirksam, propanole hingegen nicht. bakteriensporen werden nicht abgetötet. die bakterizide mindestkonzentration beträgt für n-propanol (propan- -ol) ca. - %, für iso-propanol (propan- -ol) % und für ethanol - % (v/v). aufgrund der lokalen und systemischen unbedenklichkeit sind alkohole mittel der ersten wahl zur händedesinfektion und hautantiseptik, können aber wegen ihrer raschen wirkung auch auf kleinen flächen angewendet werden. für ethanolhaltige händedesinfektionsmittel ist aufgrund der resorbierten menge kein risiko abzuleiten ). schwierig ist dagegen die risikobewertung bei anwendung von propanolen in der schwangerschaft. bei vergleichsweise geringer exposition wurden bei chirurgen nach einmaliger hygienischer und dreimaliger chirurgischer händedesinfektion im verlauf von operationen als höchste blutspiegelwerte für propan -ol , mg/l und für propan- -ol , mg/l und als mittlere absorbierte menge mg bzw. mg gemessen (below et al. aus toxikologischen und allergologischen gründen sind alkohole in kombination mit phenolen und chx nicht zur täglich wiederholten händedesinfektion zu empfehlen, zumal der nachweis der höheren wirksamkeit bisher aussteht. in hinblick auf die umweltverträglichkeit gibt es bei bestimmungsgemäßem gebrauch keine einschränkungen (kramer et al. f.) . obwohl unverdünnte alkoholkonzentrate brennbar sind, sind entzündungen innerhalb von krankenhäusern eine rarität und ausschließlich fahrlässig durch offenes feuer bzw. aus suizidaler absicht verursacht worden (kramer und kampf indikationen: mit ausnahme der sporozidie sind alle desinfektionsaufgaben ohne aldehyde mit unbedenklichen substituten realisierbar. voraussetzung hierfür ist aber eine hinreichende kenntnis der anwender über die eigenschaften der substituenten. dies gilt insbesondere, wenn aldehyde durch qav ersetzt werden. • peroxide und hypochlorite sind bei benötigter sporozidie bzgl. der langzeitverträglichkeit bei anwendungen mit wirkstofffreisetzung in die raumluft gegenüber peroxicarbonsäuren zu bevorzugen. • persäuren sind wegen der raschen sporoziden und umfassenden viruziden wirkung sowie der insgesamt höheren wirksamkeit im vergleich zu aldehyden für dialysegeräte und endoskope mittel der wahl. in frankreich wird zum personalschutz bei manueller aufbereitung peressigsäure anstelle von aldehyden zur endoskopaufbereitung empfohlen (hartemann et al. (dfg, ) . diese einstufungen verlangen ein Überdenken der bisherigen anwendung von formaldehyd zur flächen-, raumund instrumentendesinfektion (kramer et al. a ). • flächendesinfektion: es ist davon auszugehen, dass die sichere konzentration (bfr ) für die raumluft von , ppm bei der flächendesinfektion auch bei mischpräparaten in der regel überschritten wird (eickmann und thullner ) . demzufolge wären, insbesondere in kleinen und wenig belüfteten räumen, aufwendige arbeitsschutzmaßnahmen erforderlich (schwebke et al. ). sollen bei behördlich angeordneten desinfektionsmaßnahmen ggf. formaldehydhaltige desinfektionsmittel eingesetzt werden, muss durch arbeitsschutzmaßnahmen eine gefährdung ausgeschlossen werden. • raumbegasung: die raumbegasung wurde sowohl im krankenhaus als auch im krankentransport verlassen. nur zur gefahrenabwehr bei außergewöhnlichen seuchengeschehen (fock et al. ) ist sie noch für transportfahrzeuge vorgesehen. alternativ kommt die verneblung von wasserstoffperoxid in betracht (› kap. . ameisensäure als wirksamster vertreter ist bakterizid und viruzid wirksam. organische carbonsäuren sind ohne toxische risiken, umweltverträglich und werden zur konservierung, aber auch als kombinationspartner in desinfektionsmitteln, antiseptika und als antiparasitika eingesetzt (kramer et al. d ). (kramer et al. e sie besitzen ein breites bakterizides und fungizides wirkspektrum, sind begrenzt viruzid und z. t. askarizid die wirksamkeit kann je nach molekularmasse und struktur um den faktor variieren (widulle et al. ) . qav sind gegen einige erreger bei langsamem wirkungseintritt wirksam, gegen mykobakterien sowie bakteriensporen unwirksam. je größer das molekül und je schlechter die solubilisierenden eigenschaften der qav sind, desto besser ist ihre haut-und schleimhautverträglichkeit. anwendungsabhängig schädigen qav die haut aufgrund ihrer emulgierenden eigenschaften. sie werden dermal resorbiert, allerdings gibt es keine hinweise auf toxische, mutagene und karzinogene risiken sowie auf reproduktionstoxizität. toxikologisch ist die großflächige anwendung von qav nicht ausreichend charakterisiert. bei anwendung auf fußböden kommt es zu sichtbaren auflagerungen (anreicherung), die mit üblichen reinigungsverfahren nicht entfernt werden können. von den angetrockneten auflagerungen können sich beim begehen der fläche partikel ablösen, die eingeatmet werden. aufgrund der hohen oberflächenaktivität der qav ist davon auszugehen, dass eingeatmete staubpartikel das surfactant der lunge angreifen, wodurch die entwicklung einer chronisch obstruktiven lungenerkrankung (copd) verursacht und/oder gefördert werden könnte. hinzu kommt die zytotoxizität speziell für den oberen respirationstrakt. für die inhalative exposition spricht die inhalative auslösung einer dermal bestätigten allergie. bei schweinezüchtern war der gebrauch qav haltiger desinfektionsmittel mit asthma assoziiert. nach großflächiger ausbringung nach feuchteschaden in einem privathaushalt kam es zu massiven innenraumbeschwerden, sodass die wohnung verlassen werden musste. noch nach jahren lag die konzentration des qav im hausstaub -fach über dem . perzentil (kramer, below und assadian ) . auch eine mögliche resistenzentwicklung gegen qav mit kreuzresistenz gegen antibiotika (bragg et al. ; buffet-bataillon et al. ; hegstad et al. ; sidhu, heir und sørum ; tezel et al. ) spricht gegen eine unkontrolliert breite anwendung. der zusatz von benzalkonium-, benzethonium-und didecyldimethylammoniumchlorid zu händedesinfektionsmitteln ist als entbehrlich anzusehen. gegen den einsatz in instrumentendesinfektionsmitteln spricht bei gründlicher abschlussreinigung nichts. bei einsatz in flächendesinfektionsmitteln als hauptwirkstoff oder kombinationspartner ist die unverträglichkeit für einige kautschukbeläge zu beachten. bei großflächiger langfristiger anwendung ist ein inhalatives risiko nicht auszuschließen. da der einsatz der hauptvertreter polihexanid, chlorhexidindiglukonat und octenidinhydrochlorid wegen der günstigen nutzen-risiko-relation vor allem in der antiseptik seine berechtigung hat, wird auf charakterisierung in › kap. . verwiesen. die mathematischen gesetze für die absterbekinetik sind in den meisten bekannten sterilisationsverfahren gleich, sofern die physikalischen und/oder chemischen parameter während der sterilisation konstant bleiben. unter gleichen sterilisationsbedingungen unterscheidet sich allerdings die resistenz der organismen und kann z. b. durch unterschiedliche kultivierungs-und sporulierungsmethoden um den faktor differieren. unter der bedingung, dass es sich um identische mikroorganismen einer charge handelt und der sterilisationsprozess unter gleichen chemischen und/oder physikalischen bedingungen abläuft, ist die abtötungsgeschwindigkeit i. d. r. nur abhängig von der vorhandenen anzahl von mikroorganismen. das gilt zumindest in den bekannten heißluft-, dampf-, formaldehyd-und eo-sterilisationsprozessen und unter vorbehalt auch für wasserstoffperoxid(wpo)-verfahren. definition der reaktion . ordnung: die geschwindigkeit der abtötung wird durch den in gleichung ( ) stellt man gleichung um, integriert und wandelt man den natürlichen logarithmus in den dekadischen um, ergibt sich mit der neuen reaktionsgeschwindigkeitskonstanten k: ( ) lg(n /n f ) = k x t = if werden die sterilisationsbedingungen nach der o. g. definition so ausgelegt, dass von mio. teilen maximal teil mit einem erreger belastet ist, werden diese produkte in europa als "steril" bezeichnet. der direkte biologische nachweis für diesen wert ist experimentell nicht zu erbringen, er kann nur durch extrapolation der Überlebenskurve ermittelt werden. die folgende weitergehende betrachtung erfolgt am beispiel der dampfsterilisation. temperaturabhängigkeit des sterilisationsprozesses: die temperaturabhängigkeit ändert den d-wert und wird durch den z-wert beschrieben. er beschreibt, wie sich die abtötungsgeschwindigkeit der mikroorganismen mit der temperatur verändert. mathematisch ist der z-wert die temperaturdifferenz, die zur Änderung des d-werts um den faktor unter sonst gleichen sterilisationsbedingungen führt. werden d-werte bei verschiedenen temperaturen bestimmt und in einer halblogarithmischen skala gegen die temperatur aufgetragen, ergibt sich eine gerade, aus der der z-wert abgelesen werden kann (› abb. . ). mithilfe des z-werts lassen sich die d-werte bei unbekannten temperaturen wie folgt berechnen: /z = (lgd t -lgd t )/(t -t ) der f -wert wird bei einer sterilisationstemperatur von °c und einem z-wert von °c definiert und wird in der industrie für viele prozesse als referenz angegeben. weitere f-werte können definiert werden, müssen dann jedoch den zusatz der bezugstemperatur und des z-werts tragen. neuerdings wird im metrischen system der f c -wert bei °c und z = °c angegeben. es werden strahlen-, chemische und thermische sterilisationsverfahren unterschieden (› tab. . ) . strahlensterilisationsprozesse (› kap. . . ) werden im wesentlichen in der industrie eingesetzt. ihr einsatzbereich ist dort begrenzt, wo energiereiche β-oder γ-strahlen materialeigenschaften verändern. die verpackungen können absolut erregerdicht sein, da kein gasaustausch mit dem innern der sterilisierverpackung notwendig ist. chemische sterilisationsverfahren kommen für temperatursensitive produkte zur anwendung. die industrie verwendet am häufigsten eo (› kap. . . ), weil es nicht nur über Öffnungen in das innere von hohlkörpern eindringt, sondern sich in vielen (nicht in allen) kunststoffen löst und wände direkt durchdringen kann. nachteilig für die eo-verfahren im gesundheitswesen ist, dass die desorptionszeit bis zur gefahrlosen anwendung zu lang sein kann, wenn die instrumente kurzfristig wiederverwendet werden müssen. daher wird in den letzten jahren für niedertemperatur-sterili- instrumente und andere schwere güter, von denen kondensat abtropfen kann, sind auf den unteren beladeebenen des sterilisators oder beschickungswagens anzuordnen. im besonderen maß gilt das für instrumentencontainer, die so gebaut sind, dass sie viel kondensat abgeben. für gut in "weichen" verpackungen gilt: • es muss in sterilisierkörben sterilisiert, transportiert und gelagert werden. • bei klarsichtverpackungen darf die folienseite nicht nach unten weisen. • es muss so im sterilisator angeordnet sein, dass der dampfzutritt nicht behindert ist, auch nicht zu anderen gütern. • es soll bei der sterilisation nicht auf anderem gut liegen, hingegen können bis zu drei geeignete container mit einem zwischenraum übereinandergestapelt werden. die prozessvariablen müssen grundsätzlich aufgezeichnet werden. in der praxis wird im allgemeinen ein automatisch arbeitendes ge-rät zur registrierung der prozessvariablen (drücke, temperaturen, zeiten) verwendet, der verantwortliche bediener kontrolliert die aufzeichnungen und bestätigt bei der freigabe, dass der prozess korrekt abgelaufen ist. die aufzeichnung darf grafisch oder alphanumerisch erfolgen, sie muss sicherstellen, dass werte außerhalb der zulässigen grenzen identifiziert werden können. rubner ( ) die Überhitzungen sind insofern prozessrelevant, als sie bei der validierung gemessene temperaturen in diesem bereich bei der bewertung außerhalb des zulässigen temperaturbandes bringen können. deshalb müssen nicht nur die möglichkeit zur Überhitzung trockener, textiler güter bekannt sein, sondern auch die möglichkeiten zum gegensteuern. schwieriger ist die frage zu beantworten, inwieweit die gemessenen Überhitzungen zur verminderten abtötung führen. die arbeiten von spicher, peters und borchers ( wirkprinzip: die mikrobiozide wirkung von fa beruht auf der reaktion mit aminogruppen in eiweißmolekülen und aminosäuren (kirchhoff rubner berichtete über die verbesserung der mikrobioziden wirkung von fa in wasserdampf bei temperaturen < °c. in den er-jahren des . jahrhunderts wurden in großbritannien erstmals verfahren zur anwendung eines wasserdampf-fa-gemischs als "low-temperature-steam with formaldehyd" beschrieben (adam ; alder, brown und gillespie ; alder, gingell und mitchell ) . in deutschland führten marcy ( ) , in skandinavien handlos ( a handlos ( , b handlos ( , und nyström ( ) untersuchungen zur sterilisierenden wirksamkeit des fa-wasserdampf-gemischs durch. durch mecke ( ) wurde in deutschland ein verfahren, das im gegensatz zu bisherigen verfahrenstemperaturen zwischen und °c bei °c arbeitete, beschrieben. grundlagenuntersuchungen an den in deutschland entwickelten sterilisatoren wurden in den er-jahren von spicher und borchers ( , für die praxis ist zu fordern, dass die für das verfahren zulässigen konfigurationen der mp definiert und bei zu erwartenden diffusionsverzögerungen vor allem in hohlkörpern die grenzen durch den hersteller genau benannt werden. der jeweilige mp-hersteller muss ebenfalls angeben, ob und unter welchen voraussetzungen sein produkt mit diesem verfahren sterilisiert werden kann. zur weiteren verfahrensoptimierung sollte die penetration des sterilisiermittels an alle inneren und äußeren oberflächen verbessert werden, da derzeit der einsatz der geräte für das gesundheitswesen noch lücken offenbart. als verpackungsmaterial können nur nicht metallhaltige, hydrophobe materialien verwendet werden. normalerweise wird tyvek-folie bzw. polyprolylen-vlies verwendet. es dürfen keine zellulosehaltigen verpackungen eingesetzt werden. in tyvek-folie verpackte mp werden in offenen kunststoffkästen in die kammer eingebracht. die anforderungen an anordnung und beladungsdichte in siebkorb und kammer entsprechen im wesentlichen denen anderer sterilisationsverfahren. zusätzliche hinweise sind den herstellerangaben zu entnehmen. da die prozessführung automatisch abläuft und redundant überwacht wird, muss davon ausgegangen werden, dass die sterilisation bei ablauf des sterilisationsprozesses ohne störung ordnungsgemäß erfolgt ist. danach kann das sterilgut freigegeben werden. der geräteausdruck ist der dokumentation beizufügen. bezüglich der validierbarkeit der im gesundheitswesen eingesetzten geräte ist festzustellen, dass die hersteller der sterilisatoren fir-meneigene mikrobiologische validierungen in verbindung mit der testung von physikalischen rahmenbedingungen anbieten. ein direkter nachweis am jeweiligen konkreten mp unter praxisbedingungen (performance qualification) erfolgt nicht, d. h., der nachweis, dass vor allem an den inneren oberflächen der mp in jedem fall die physikalischen bedingungen für die aufrechterhaltung der gasphase des sterilisiermittels eingehalten werden, ist derzeit nicht gegeben. im industriellen bereich müssen entsprechende validierungen vergleichsweise am realen mp erfolgen. die vorteile der h o -gas-sterilisation, wie geschwindigkeit, rückstandsarmut, einfachheit für den anwender, können zurzeit im medizinischen alltag nur eingeschränkt genutzt werden. eine verbesserung des penetrationsverhaltens des sterilisiermittels und der penetrationsbedingungen im sterilisationsprozess würden eine Überschreitung der o. a. grenzen des verfahrens möglich machen. durch veränderte prozessführung, geeignete, vereinbarte anweisungen und technische hilfsmittel (insbes. solche zur rückstandsfreien vorreinigung der güter und zur verfahrensvalidierung) dürfte es möglich werden, das verfahren weiterzuentwickeln. während bei dampfsterilisationsverfahren den mikroorganismen durch kondensation feuchte zugeführt wird, trocknet man bei der sterilisation mit trockener hitze die mikroorganismen während der erwärmung aus und zerstört die strukturen. dabei ist es besonders wichtig, dass die sterilisiertemperatur während der einwirkzeit an allen stellen im gut gegeben sein muss (› abb. . eine weitere möglichkeit zur erregerdichten verpackung von mp sind wärmebeständige folienverpackungen. hier ist darauf zu achten, dass das jeweilige folienschweißgerät an das temperaturniveau angepasst ist, da die siegelnähte bei einer temperatur oberhalb der heißluftsterilisationstemperatur verschweißt werden müssen. beladeschema: die kammer ist so zu beladen, dass die luft ungehindert zwischen allen oberflächen der packstücke zirkulieren kann (› abb. . ) . der nutzraum darf nicht so überfrachtet werden, dass die zirkulation behindert wird. jedes einzelne teil muss derart eingelegt werden, dass es von allen seiten von heißluft umströmt wird. bei sterilisatoren mit zwangskonvektion ist die richtung des luftstroms zu berücksichtigen. größere gegenstände können einen windschatten verursachen, in dem die erwärmung beträchtlich verzögert werden kann. ein nicht selten zu beobachtender fehler ist die zusammenstellung einzelner objekte zu blöcken. weiterhin ist sicherzustellen, dass die zu sterilisierenden objekte wie bei jedem anderen sterilisationsprozess trocken beladen werden. bei nassen gegenständen wird ein teil der wärme zur verdunstung der feuchtigkeit verbraucht und deren erwärmung dadurch verzögert. die freigabe des sterilguts obliegt der dafür ausgebildeten und benannten person. die freigabekriterien einer erfolgreichen sterilisation werden in den bedienungsanleitungen der geräte benannt. entscheidend sind die stabile einhaltung der prozessabläufe und deren dokumentation. die jeweiligen chargen sind zu bezeichnen und zu dokumentieren. wirkprinzip: in gammaanlagen wird als strahlenquelle fast ausschließlich co- , sehr selten cs- eingesetzt. elektronenbeschleuniger (β-strahler) nutzen beschleunigte elektronen bis zu einer energie von mev. in röntgenanlagen wird ein target mit beschleunigten elektronen bestrahlt und die sekundärstrahlung, die röntgenstrahlen (x-rays), genutzt. die ionisierenden strahlen bewirken bei ausreichend hoher energie ionisierungen, die in der reihenfolge abnehmender empfindlichkeit bakterien, pilze, bakteriensporen und viren abtöten. durch einsatz der strahlen werden zuerst zellteilungsvorgänge beeinträchtigt, danach folgt die verlangsamung des wachstums, ehe es nach ausschaltung der atmung und fermentation zum zelltod kommt. in der regel wird die strahlensterilisation wegen der hohen investitionen, des strahlenschutzes und der hohen kapazität einer anlage nur industriell genutzt und durch serviceunternehmen angeboten. die anlagen unterliegen den bedingungen der strahlenschutzverordnung. verpackung: das sterilisiergut wird in der transport-bzw. endverpackung, z. b. in exotoxine sind gewebeschädigende proteine. sie werden von bakterien, z. b. clostridien und bazillen, aktiv in die umgebung abgegeben, sind durch erhitzung inaktivierbar und lösen typische erscheinungen aus. exotoxine können innerhalb des infizierten wirtsorganismus gebildet werden (z. b. diphtherie-, scharlachtoxin) oder nach bildung außerhalb des körpers z. b. durch nahrungsverzehr aufgenommen werden (z. b. botulinustoxin). letzteres wird seit über jahren bei schweren neurologischen leiden und neuerdings als anti-aging-mittel zur glättung faltiger haut eingesetzt (hacker ) . zu den exotoxinen gehören auch die superantigene von strepto-und staphylokokken. diese vernetzen und stimulieren spezifisch makrophagen und cd -t-lymphozyten, sodass große mengen botenstoffe gebildet werden und eine ähnliche wirkung eintritt wie bei endotoxinen. ein beispiel ist das sog. toxic-shock-toxin. endotoxine sind lipopolysaccharide (lps) der äußeren membran gramnegativer bakterien. sie werden vor allem beim absterben (lyse), aber auch bei der zellteilung vitaler bakterien freigesetzt (rietschel und brade ) . ihre wesentliche toxische komponente, das lipid a, ist hitzestabil. die wirkung ist prinzipiell unabhängig von der bakteriellen herkunft, die wirkungsbreite sehr unterschiedlich. endotoxine können als konstanter stimulus den tonus körpereigener immunabwehr aufrechterhalten (leinmüller es gibt hinweise, dass der regelmäßigen sichtkontrolle und reinigung/desinfektion des wassertanks von kleinsterilisatoren mehr aufmerksamkeit zu schenken ist. strobel ( ) beschreibt postoperativ eine reizung der augenvorderkammer, die durch endotoxineinbringung, ausgehend vom kontaminierten speisewasserbehälter des dampfkleinsterilisators, verursacht sein könnte. dazu bestimmten martin und daily ( ) die erreger-und endotoxingehalte im wasserreservoir eines dampfkleinsterilisators. whitby und hitchins ( ) die ausbildung muss sicherstellen, dass das personal der zsva die mit der aufbereitung eines mp anfallenden arbeiten selbstständig ausführen kann. weiterbildung: die schnellen veränderungen im gesundheitswesen, neue verpackungssysteme und schwieriger aufzubereitende instrumente erfordern die ständige weiterbildung. in allen abteilungen, in denen aufbereitet wird, muss jährlich eine dokumentierte einweisung des personals in den betrieb von sterilisationsgeräten und rdg erfolgen. zur gewährleistung der qualifikation im niedergelassenen bereich ist der erwerb der sachkunde für die instandhaltung von mp in der ärztlichen praxis als gemeinsame initiative von dgsv, dgkh und dem berufsverband der deutschen hygieniker eingeführt worden. marc thanheiser und martin mielke mit krankheitserregern kontaminierte mp wie z. b. chirurgische instrumente können bei erneuter anwendung zu infektionen führen. auch darf von mp bei der anwendung keine gefahr von gesundheitsschäden durch pyrogenbedingte, allergische oder toxische reaktionen sowie aufgrund veränderter technisch-funktioneller eigenschaften des mp ausgehen. aus diesen gründen müssen mp entsprechend der art der vorherigen und folgenden anwendung sowie der konstruktiven und materialtechnischen eigenschaften vor einer erneuten anwendung aufbereitet werden. die ordnungsgemäße aufbereitung von mp ist in § der mpbetreibv (medizinprodukte-betreiberverordnung, ) auch in einer rechtsnorm angesprochen. dort wird unter anderem aufgeführt, dass die aufbereitung von bestimmungsgemäß keimarm oder steril zur anwendung kommenden mp unter berücksichtigung der angaben des herstellers mit geeigneten validierten verfahren so durchzuführen ist, dass der erfolg dieser verfahren nachvollziehbar gewährleistet und die sicherheit und gesundheit von patienten, anwendern oder dritten nicht gefährdet wird. eine ordnungsgemäße aufbereitung wird vermutet, wenn die gemeinsame empfehlung der krinko am rki und des bfarm zu den "anforderungen an die hygiene bei der aufbereitung von medizinprodukten" (krinko und bfarm a) beachtet wird. die in § mpbetreibv (medizinprodukte-betreiberverordnung, ) genannte empfehlung, im folgenden als krinko-bfarm-empfehlung bezeichnet, dient als fachliche basis für die nachfolgenden ausführungen. auf den amtlichen originaltext der empfehlung wird ausdrücklich hingewiesen (krinko a). für die korrekte aufbereitung von mp ist der betreiber verantwortlich. basierend auf einer risikobewertung und einstufung (› kap. . . ), hat der für die aufbereitung verantwortliche unter berücksichtigung der angaben des herstellers schriftlich festzulegen, mit welchen verfahren (in allen einzelschritten) und unter welchen bedingungen (z. b. räume, arbeitsmittel, qualifikation des personals) seine mp aufbereitet und gelagert werden. die aufbereitung und die stete erfüllung der anforderungen setzt ein qm-system voraus, und es sind vor der aufbereitung von mp die zuständigkeiten für alle schritte der aufbereitung zu regeln und zu dokumentieren sowie die einzelschritte der aufbereitung unter angabe der jeweilig notwendigen prüfungen in standardarbeitsund betriebsanweisungen festzulegen. dabei ist zu beachten, dass der für die verschiedenen prozessschritte jeweils zuständige seine aufgabe aufgrund seiner position und qualifikation (aus-, weiterund fortbildung) auch tatsächlich erfüllen kann (s. hierzu auch die anlage "sachkenntnis des personals" der krinko-bfarm-empfehlung; rki ). voraussetzung für die aufbereitung ist, dass die eignung der zur anwendung kommenden aufbereitungsverfahren und die wirksamkeit im rahmen einer produkt-/produktgruppenspezifischen prüfung und validierung belegt wurden (din en iso : - es ist zweckmäßig, bereits vor der anschaffung eines mp durchführbarkeit und aufwand der aufbereitung zu überdenken und die anwender sowie die für die aufbereitung und für die hygiene zuständigen in die entscheidung über die beschaffung des mp sowie die erforderlichen mittel und geräte für die aufbereitung einzubeziehen. hinsichtlich der art der anwendung und des sich daraus ableitenden risikos können mp eingestuft werden in: (bertram et al., ) . einige dieser formulierungen haben auch bakterizide und viruzide eigenschaften (beekes et al., ) . von den zur verfügung stehenden sterilisationsverfahren wurde bisher nur für die dampfsterilisation (insbesondere °c, - min) und für bestimmte wasserstoffperoxid-basierte verfahren eine relevante wirkung auf prionen nachgewiesen (rogez-kreuz et al. freigabe zur anwendung: die aufbereitung von mp endet mit der freigabe zur anwendung. diese erfolgt auf der basis der Übereinstimmung der bei der aufbereitung jeweils ermittelten prozessparameter mit denen der validierungsprotokolle und schließt die durchführung sowie die dokumentation der täglichen routineprüfungen, die Überprüfung und dokumentation des vollständigen, korrekten prozessverlaufs (chargenbezogene routineprüfungen und chargendokumentation), die Überprüfung der verpackung auf unversehrtheit und trockenheit sowie die Überprüfung der kennzeichnung ein. die die aufbereitung beschreibenden sops müssen auch die art und dokumentation der freigabeentscheidung und das vorgehen bei abweichungen vom korrekten prozessablauf enthalten. dokumentation: die im rahmen der aufbereitung erfassten messwerte der prozessparameter und die freigabeentscheidung sind mit bezug auf die freigebende person und die charge zu dokumentieren und mindestens jahre aufzubewahren. sonstige rechtsvorschriften zu aufbewahrungsfristen (z. b. patientendokumentation) bleiben hiervon unberührt. dabei darf weder der ursprüngliche inhalt einer eintragung unkenntlich gemacht werden, noch dürfen Änderungen vorgenommen werden, die nicht erkennen lassen, ob sie während oder nach der ursprünglichen eintragung vorgenommen worden sind. die aufzeichnungen und nachweise sind den zuständigen behörden auf verlangen vorzulegen. transport und lagerung: transport und lagerung dürfen die eigenschaften des aufbereiteten mp nicht nachteilig beeinflussen. bei der lagerung von aufbereiteten mp sind die angaben des herstellers des mp und des verpackungsmaterials zu berücksichtigen. die lagerdauer ist abhängig von der qualität des verpackungsmaterials, der dichtigkeit der siegelnähte und den lagerbedingungen. davon abhängig sind auch lagerfristen von über sechs monaten denkbar. keimarme (semikritische) mp müssen so gelagert werden, dass eine rekontamination während der lagerung vermieden wird. . . validierung: beleg der reinigungs-, desinfektions-und sterilisationsleistung weder das mit der desinfektion angestrebte ziel der "keimarmut" noch das mit der sterilisation verfolgte ziel der "sterilität" sind an dem aufbereiteten mp unmittelbar erkennbar. auch das ziel "sauberkeit" des reinigungsprozesses ist bei mp mit nicht direkt einsehbaren, z. b. inneren oberflächen, nicht direkt beurteilbar. bei desinfektion und sterilisation, und teilweise bei der reinigung handelt es sich um prozesse, deren effektivität nur durch anwendung validierter verfahren und durch Überwachung von relevanten prozessparametern, die im rahmen der validierung definiert werden, belegt werden kann. die validierung soll dem mp und seiner risikobewertung und einstufung angemessen sein. die produktspezifische validierung von aufbereitungsprozessen wird in der regel vom hersteller durchgeführt (din en iso : - ) . soweit keine einheitlichen produktchargen gebildet werden können, müssen die dokumentierten prüfungen im rahmen der validierung an produkttypen bzw. prüfmodellen erfolgen, die nachweislich repräsentativ für alle wesentlichen merkmale der zu bildenden gruppe von mp anzusehen sind. die validierung führt zu einem dokument, aus dem hervorgeht, auf welche weise ein zuvor definierter zustand (z. b. sterilität) reproduzierbar erbracht wird. dieses dokument enthält auch angaben darüber, welche daten für die Überwachung des prozesses erforderlich sind und wie diese daten zu interpretieren sind. die qualität der maschinellen aufbereitung wird abhängig vom jeweiligen verfahren der reinigung, desinfektion und sterilisation bei reinigungs und desinfektionsverfahren sind speziell maschinelle verfahren validierbar (din en iso ) . Überwachungs-, kontroll-und warnsysteme der maschinen stellen die voraussetzungen für eine gesicherte reinigung und desinfektion und damit aufbereitung dar. manuelle reinigungs-und desinfektionsverfahren sind schwieriger zu standardisieren und daher weniger zuverlässig reproduzierbar. sofern sie eingesetzt werden, müssen sie stets nach sops und mit auf wirksamkeit geprüften und materialverträglichen mitteln und verfahren durchgeführt werden. auch diese verfahren bedürfen einer validierung und periodischer prüfungen. sterilisationsverfahren sind unter der voraussetzung ihrer anwendung bei rückstandsfrei gereinigten mp vollständig validierbar. marianne abele-horn (mitherausgeberin für dieses kapitel) hintergrund die wirksamkeit von antibiotika ist gefährdet, da resistenzen gegen antibiotika weltweit zunehmen. dies stellt ein ernst zu nehmendes problem für die gesundheit der bevölkerung dar. daher hat die who die antibiotikaresistenz als global threat eingestuft; sie wird auf eine stufe gestellt mit anderen problemen wie umweltverschmutzung oder globaler erwärmung. neue, vielversprechende wirkstoffe sind nicht in aussicht, was ein problem für die therapierbarkeit von bakteriellen infektionen in der zukunft aufwirft. die entwicklung und verbreitung von antibiotikaresistenten erregern wird von einer vielzahl von faktoren beeinflusst. neben hygienemaßnahmen spielt der umsichtige einsatz von antibiotika eine wesentliche rolle. › abb. . stellt den verbrauch von antibiotika in der humanmedizin in deutschland dar. der verbrauch in der veterinärmedizin in deutschland liegt mit tonnen noch höher (stand ). die zunahme von antibiotikaresistenzen ist eng gekoppelt an die art und quantität des antibiotikaeinsatzes sowohl in der humanmedizin als auch in tierhaltung und landwirtschaft. so können unter dem durch die antibiotikatherapie entstehenden selektionsdruck sowohl resistente erreger (gegen das verwendete antibiotikum) selektioniert werden als auch resistente mutanten des zu behandelnden erregers einen Überlebensvorteil erlangen und sich ungehindert vermehren. vielfach kommt es in abhängigkeit von bakterienspezifischen faktoren und äußeren umständen (z. b. inadäquaten hygienemaßnahmen, horizontalem gentransfer) zur weiterverbreitung in die umgebung (mensch, tier, umwelt wie z. b. wasser). durch die globalisierung insbesondere im hinblick auf den warenverkehr und die mobilität von personen können auch zunächst lokal auftretende resistenzen in kurzer zeit weit verbreitet werden. ein beispiel sind die "neu-dehli-metallo-betalaktamase (ndm )"-tragenden erreger, die vom indischen subkontinent in zahlreiche länder eingetragen wurden. ndm- resistenzgene -um bei diesem beispiel zu bleiben -sind auf mobilen plasmiden lokalisiert, die zwischen unterschiedlichen gramnegativen spezies übertragen werden können (e. coli, klebsiellen, serratien, acinetobacter spp. usw.). die antibiotikaresistenz ist somit ein globales problem, das die ökologische gesamtsituation beeinflusst. es gibt einen zusammenhang zwischen der menge an antibiotikaverordnungen und der resistenzenzwicklung. dieser ist unterschiedlich schnell und nicht unbedingt in linearer dosis-wirkungsbeziehung. daraus folgt, dass eine antibiotikaresistenz oft nicht und vor allem nicht unmittelbar reversibel ist. trotzdem kann ein sorgsamer umgang mit antibiotika den selektionsdruck reduzieren und die resistenzsituation positiv beeinflussen. antibiotic stewardship zielt auf eine verbesserte qualität der antibiotikatherapie: sie soll für den einzelnen patienten bei minimaler toxizität und resistenzentwicklung das bestmögliche klinische behandlungsergebnis erreichen. eine gute antibiotikaverordnungspraxis umfasst z. b. • den einsatz von antibiotika nur dort, wo sie therapeutisch oder prophylaktisch indiziert sind, • die optimierung der antibiotikaregime hinsichtlich der auswahl des antibiotikums, der applikationsart, der dosierung und der dauer der therapie bzw. der prophylaxe. dadurch soll der individuelle nutzen für den patienten verbessert und der selektionsdruck auf die bakterienpopulationen und die kosten für das gesundheitssystem minimiert werden. beispiele für einen nicht rationalen einsatz von antibiotika zeigt› tab. . . unter dem begriff "antibiotic stewardship" (abs) werden alle maßnahmen zusammengefasst, die einer verbesserung der antibiotikaverordnungspraxis sowohl in der stationären wie auch in der ambulanten patientenversorgung dienen (deutsche gesellschaft für infektiologie ). antibiotic stewardship erfordert eine systematische herangehensweise, in der verschiedene aktivitäten und maßnahmen in sinnvoller weise miteinander koordiniert werden. mindestens tonnen antibiotika in der humanmedizin in deutschland verbraucht ( in der s -leitlinie "strategien zur sicherung rationaler antibiotikaanwendungen im krankenhaus" werden die wesentlichen eckpunkte von abs bzw. abs-programmen beschrieben (deutsche gesellschaft für infektiologie ) . sie umfassen die schaffung und aufrechterhaltung von organisatorischen und strukturellen vor-aussetzungen. unabdingbar dafür ist die finanzielle und personelle unterstützung der klinikleitung für die etablierung eines multidisziplinären abs-teams (› abb. . ) . die leitlinie fordert als notwendige personalressource für ein abs team mindestens , vollzeitstellen pro betten. daten zu antibiotikaverbrauch, infektionenserregern und resistenz sollen mindestens einmal jährlich für das gesamte krankenhaus und aufgeschlüsselt für einzelne fachabteilungen verfügbar sein (vor allem für abteilungen mit hohem verbrauch, z. b. intensivstationen) (› abb. . ) . ohne messung der antibiotikaverordnungsdichte ist eine nachhaltige umsetzung intelligenter verordnungsstrategien nicht möglich. in der humanmedizin hat sich für erwachsene patienten als methode der verbrauchsmessung die anzahl der tagesdosen (defined daily dose, ddd nach who atc) pro einwohner oder versicherter für den ambulanten bereich und pro patiententage im stationären bereich durchgesetzt (schweickert et al. das abs-team erstellt nach aktuellem stand des wissens unter bezugnahme auf vorhandene empfehlungen von fachgesellschaften klinikinterne leitlinien. diese leitlinien zu therapie und prophylaxe müssen regelmäßig aktualisiert werden und sind ein wichtiger bestandteil der kernstrategien jedes abs-programms (› tab. . die meisten studien zur effektivität der abs belegen eine reduktion von antiinfektivaverordnungen um - %, eine verkürzte therapiedauern und eine signifikante kostenreduktion trotz initial erforderlicher investitionen. in › tab. . ist die evidenz von interventionen zusammengefasst (davey et al. ) . diese cochrane analyse zeigt auch, dass gezielte abs-interventionen bezüglich mikrobiologischer endpunkte (z. b. anteil von erregern mit speziellen resistenzen und multiresistenzen) meist erst mit einer verzögerung von mindestens monaten effektiv sind, während Änderungen in bezug auf den antibiotikaverbrauch oft bereits nach monat erreicht werden. ganz entscheidend zur eindämmung von mre und c. difficile ist die enge strukturell-organisatorische zusammenarbeit von klinischen infektiologen, mikrobiologen und krankenhaushygienikern/ hygienefachpersonal. abs-programme sind nur dann effektiv, wenn sie die verordnungspraxis systematisch und kontinuierlich verbessern. wenn sie zeitlich begrenzt sind und es dem abs-team nicht gelingt, die behandelnden Ärzte von der notwendigkeit entsprechender interventionen zu überzeugen, besteht die gefahr, dass die erreichten verbesserungen in der antibiotikaverordnung ohne nachhaltige wirkung bleiben (gerber et al. (gerber et al. und szymczk et al. ). das unterstreicht die eindeutige empfehlung der s -leitlinie, kontinuierlich ressourcen in form von facharztstellen, arbeitszeit und weiterbildung für ein erfolgreiches abs-programm zur verfügung zu stellen. in deutschland werden jährlich in krankenhäusern etwa , mio. operationen mit einer durchschnittlichen postoperativen wundinfektionsrate von % durchgeführt (gastmeier et al. ; siehe auch deutsche fassung der literaturstelle von gastmeier und v. a. bqs portal: hier werden die daten von unseren kollegen in deutschland unter cdc a -a den ssi-definitionen nach dokumentiert). uneinheitlich verwendete definitionen der ssi (barie ) und verkürzung der verweildauer erschweren die exakte erfassung, sodass vermutlich mit einer höheren ssi-rate gerechnet werden muss. sie kann nach aseptischen eingriffen bis zu % und nach intraabdominellen eingriffen bis zu % betragen (bratzler und houck ; rovera et al. ). die wundinfektionsrate (ssi-rate, entsprechend der anglo-amerikanischen literatur ssi = surgical site infection) erfasst alle infektionen nach chirurgischen eingriffen (oberflächliche und tiefe infektionen sowie infektionen von organen und körperhöhlen). empfehlungen und leitlinien sowie die einführung von kontrollsystemen können die prophylaxe verbessern, sie aber nicht flächendeckend etablieren (bratzler et al. ; forbes et al. ; kritchevsky et al. ; pan et al. ; papaioannidou et al. ; rüden et al. ; warters et al. ). vorschläge zur verbesserungen beinhalten z. b. checklisten im rahmen von anästhesieprotokollen und die lückenlose dokumentation der maßnahmen zur perioperativen prophylaxe (fry ; haynes et al. ; rosenberg et al. ; wax et al. ; willemsen et al. ). selbst bei leitlinienkonformer pap werden jedoch nicht in allen fällen ausreichende wirkspiegel erreicht (caffarelli et al. ; dalley et al. ; koopman et al. (bratzler et al. ; sign ). • ziel der pap ist das vermeiden postoperativer wundinfektionen und nicht anderer ni (z. b. gefäßkatheter-assoziierte blutstrominfektion, beatmungsassoziierte pneumonie, harnwegskatheter-assoziierte hwi). bei der indikationsstellung sind neben dem grad der bakteriellen besiedlung und der wundklassifikation (cruse und foord ; › tab. . ) je nach wundkategorie ein individuelles infektionsrisiko und patienteneigene sowie op-bedingte besonderheiten zu berücksichtigen. daher können empfehlungen nicht nur auf der basis evidenzbasierter klinischer studien und metaanalysen erarbeitet werden, sondern müssen auch gut ausgewiesene experimentelle und klinische studien, die nachweislich wundunabhängige risikofaktoren für eine ssi oder infektiöse komplikationen (z. b. pneumonie, harnweginfektion, sepsis) anderer art beinhalten, berücksichtigt werden. bei besonders schwerwiegenden infektionskomplikationen (z. b. nach intrakraniellem eingriff) wird die pap unabhängig von risikofaktoren empfohlen. unabhängig von der art des eingriffs wurden risikofaktoren aus unterschiedlichsten patientenkollektiven und studien zusammengetragen und konnten in einzelnen untersuchungen als statistisch signifikante faktoren ausgewiesen werden. es kann eine einteilung in patienteneigene, prä-, intra-und postoperative risikofaktoren vorgenommen werden (› tab. . ) . patienteneigene risikofaktoren sind natürliche, nicht änderbare risiken wie alter oder geschlecht, aber auch nicht korrigierbare defizite bei dringlichen eingriffen wie diabetes mellitus, immunabwehrschwäche, reduzierter allgemeinzustand, Übergewicht und mangelernährung. patienten mit karzinombedingter chirurgischer intervention besitzen ein signifikant erhöhtes ssi-risiko und sollten grundsätzlich eine pap erhalten. die auswahl des antibiotikums muss die lokalisation des tumors berücksichtigen. wichtige präoperative risikofaktoren sind ergänzend zu › tab. eine generelle pap bei allen aseptischen eingriffen wird nicht empfohlen. es gibt aber zahlreiche hinweise, dass besonders patienten mit infektionsrisiken bei aseptischen eingriffen von einer pap profitieren. bei aseptischen eingriffen mit fremdkörperimplantation ist die pap etabliert. jede pap birgt das risiko einer resistenzentwicklung und der selektion von erregern mit bereits bestehender unempfindlichkeit gegenüber gebräuchlichen antibiotika (ulger et al. ). initiale empfehlungen zum applikationszeitpunkt einer wirksamen pap gehen auf tierexperimentelle untersuchungen von burke zurück (burke die effektive periode, in der die pap ssi signifikant reduziert, ist stunde vor bis stunden nach beginn des eingriffs, spätestens jedoch vor wundverschluss (bates et al. , classen et al. , weber et al. ). im klinischen routineablauf bietet sich bei i. v. verabreichung der zeitpunkt der narkoseeinleitung, also etwa - minuten vor der inzision an. der späteste noch sinnvolle zeitpunkt für eine antibiotikaprophylaxe ist intraoperativ, z. b. beim auftreten von komplikationen. die ssi-rate nimmt mit jeder stunde nach dem hautschnitt signifikant zu, wenn die antibiotikagabe verzögert wird oder die applikation länger als stunde vor op-beginn erfolgt. eine antibiotikagabe nach wundverschluss hat keinen einfluss auf die ssi-rate. da das optimale zeitfenster auch von patientenabhängigen pharmakokinetischen parametern der eingesetzten substanzen und der art der applikation (bolusgabe, kurz-, dauerinfusion) abhängt, ist bei den heute verwendeten moderneren antibiotika mit kürzeren halbwertszeiten und rascher verteilung in die kompartimente eine zur inzision möglichst zeitnahe verabfolgung wünschenswert (zelenitzky et al . ) . der nutzen einer dauerinfusion von betalaktamantibiotika wird diskutiert (waltrip et al. , suffoletta et al. ). bei der dosierung sollten erhöhte oder erniedrigte verteilungsräume der patienten berücksichtigt werden. einen hinweis können körpermasse, body mass index, einlagerungen, drainagen u. a. geben. eine standarddosierung kann nur unter idealbedingungen erfolgen. bei heute üblichen substanzen sind häufig höhere dosierungen notwendig (hutschala et al. ). präoperativ intraoperativ postoperativ • alter (zunahme pro dezennium; lizan-garcia, garcia-caballero und asensio-vegas , zelenitsky et al. ) • diabetes mellitus (zelenitsky et al. ) • immuninkompetenz • reduzierter allgemeinzustand • Übergewicht (lofgren , itani et al. (centofanti et al. ) • frühe re-op wegen blutungen (centofanti et al. ) • liquorleck, externer shunt (lietard et al. ) bei einer op-dauer < stunden ist die einmalige gabe des antibiotikums für eine effektive prophylaxe ausreichend und der mehrmaligen gabe bei eingriffen unterschiedlicher kategorie (kontaminiert bis aseptisch) nicht unterlegen (carignan ; fujita et al. ; hellbusch et al. ; hutschala et al. ; su et al. ; suehiro et al. eine antibiotikagabe darüber hinaus gilt als therapie und nicht als prophylaxe. sie kann notwendig werden, wenn infektionsherde operativ nicht vollständig beseitigt werden konnten (z. b. bei septischer cholangitis, eitriger peritonitis, nach appendix-oder divertikelperforation u. a.) und ein anhaltend hohes infektionsrisiko für den patienten besteht. bei eingriffen an extremitäten in blutleere wurden üblicherweise die antibiotikagabe minuten vor anlegen der blutsperre und eine folgedosis nach eröffnen der blutsperre empfohlen. die auswahl erfolgt vorrangig nach dem erwarteten erregerspektrum, das aus der normalen bzw. pathologischen besiedlung des op-gebiets und seiner unmittelbaren haut-und schleimhautumgebung resultiert. falls möglich, sollte sich die auswahl am ergebnis der mikrobiologischen diagnostik orientieren (zutt et al. ) . antibiotika zur pap sollten ihre wirksamkeit in klinischen studien bewiesen haben, nebenwirkungsarm und kostengünstig sein. um das zeitfenster optimal für die prophylaktische wirkung des antibiotikums zu nutzen, müssen sich seine applikationsart und dosis nach seinen eigenschaften richten. es gibt nur wenige klinische studien, die pharmakokinetische daten, applikationszeitpunkt und substanzwahl mit ssi-raten korrelieren. betalaktamantibiotika: die mhk für relevante erreger werden bei parenteraler gabe eines betalaktamantibiotikums im serum und gewebe i. d. r. innerhalb weniger minuten erreicht (wittmann, welter und schassan ) . die pharmakokinetik der antibiotika im serum korreliert mit der dauer der wirksamkeit im gewebe (novelli ) . pharmakokinetische parameter ändern sich mit der substanz und den organfunktionen des patienten. betalaktamantibiotika mit halbwertszeiten von - stunden wie cefazolin, cefuroxim oder ampicillin-sulbactam (respektive amoxicillin-clavulansäure) sollten möglichst zeitnah zum eingriff gegeben und intraoperativ nach stunden op-dauer wiederholt werden (colombo et al. ). der vorteil der betalaktamantibiotika mit langer halbwertszeit (z. b. ceftriaxon) liegt in der einmalgabe auch bei länger dauernden eingriffen. aminoglykoside, falls überhaupt eingesetzt, müssen hoch dosiert (gentamicin , mg/kg körpergewicht) werden (zelenitsky et al. (zelenitsky et al. , , um effektive spiegel auch bei wundverschluss zu erreichen. der stellenwert der aminoglykoside in der pap ist heute gering. primäres ziel der pap ist die senkung der ssi-rate, sekundäres ziel die vermeidung lokaler und systemischer postoperativer infektionskomplikationen. die pap sollte risikoadaptiert und individualisiert erfolgen. eine zu frühe gabe des antibiotikums und auch die gabe nach dem wundverschluss sind nutzlos. die fortführung der pap über die op (in der herzchirurgie maximal über die ersten stunden nach op) hinaus bedarf besonderer indikation und kann eigentlich nicht mehr als pap bezeichnet werden (präventive therapie?). bei der auswahl des antibiotikums sind risikofaktoren auf seiten des patienten und ggf. auch die lokale erreger und resistenzstatistik zu berücksichtigen. ein besonderes augenmerk gilt dabei möglichen sekundären infektionen, die v. a. durch gramnegative erreger verursacht werden. es sollten nur substanzen eingesetzt werden, bei denen entsprechende indikationen nachgewiesen sind. die meisten erfahrungen liegen für den einsatz der β-lactam-antibiotika vor. die auswahl der substanzen orientiert sich in erster linie am erregerspektrum und an der pharmakokinetik. für den individuellen patienten ist das risiko der resistenzentwicklung gering. das gilt jedoch nicht für das gesamtkollektiv einer klinik. Ökonomische gesichtspunkte sind wichtig, auch wenn die kosten der pap geringer sind als die kosten postoperativer infektionskomplikationen. spätestens seit semmelweis ist klar, dass postoperative wundinfektionen (ssi) nicht "schicksalhaft" auftreten, sondern zumindest in ¼ der fälle als iatrogene komplikationen angesehen werden müssen, die bei entsprechenden hygienischen maßnahmen auf ein mindestmaß reduziert werden können. die immense sozioökonomische bedeutung der sogenannten "surgical site infections" (ssi) wird anhand bundesweit erhobener epidemiologischer daten deutlich: in der nationalen prävalenzstudie ( ) konnte zwar gezeigt werden, dass in deutschland die rate an nosokomialen infektionen (ni) mit , % im europäischen vergleich stabil niedrig ist (in vergleichsstudien international zwischen , % und , %), letztlich aber doch bei mio. stationär behandelten patienten im jahr dementsprechend ni auftreten. da ein viertel der ni wundinfektionen sind, bedeutet das jährlich etwa wundinfektionen. diese zahlen werden auch durch auswertung der daten des krankenhaus infektions surveillance systems (kiss) bestätigt. eine postoperative wundinfektion verursacht durchschnittlich € mehrkosten und verlängert den krankenhausaufenthalt um , tage. hochgerechnet bedeutet dies eine belastung für die versicherungssysteme von fast € mehrkosten und zusätzliche krankenhausbehandlungstage pro jahr in deutschland. darüber hinaus gibt es hinweise darauf, dass eine postoperative wundinfektion ein unabhängiger risikofaktor für patienten darstellt, im postoperativen verlauf zu versterben oder zumindest intensivmedizinische behandlung zu benötigen. es ist anerkannt, dass ein teil der ssi durch die strikte einhaltung entsprechender präventivmaßnahmen vermieden werden kann. ein wesentlicher beitrag zur vermeidung postoperativer wundinfektionen kann durch die korrekt durchgeführte perioperative antibiotikaprophylaxe (pap) geleistet werden. es gibt zahlreiche empfehlungen zum einsatz der pap. genannt werden sollen hier stellvertretend die empfehlungen der paul-ehrlich-gesellschaft für chemotherapie von (wacha ) und die krinko-empfehlung zur prävention postoperativer infektionen im operationsgebiet von (krinko . darüber hinaus wurde im jahr vom european centre for disease prevention and control (ecdc) eine evidenzbasierte leitlinie zur optimierung der pap veröffentlicht (bratzler et al. ; sign ) . ziel der pap ist einzig und allein die vermeidung postoperativer wundinfektionen (ssi). es gibt zwar daten, die darauf hinweisen, dass bei korrekt angewandter pap auch postoperative pneumonie und intraabdominelle infektionen (abszesse) positiv beeinflusst werden. diese daten sind aber nicht ausreichend valide und stammen meist aus der nachträglichen auswertungen von studien, deren primärer endpunkt das auftreten von wundinfektionen war. hervorzuheben ist, dass die pap weitere hygienische maßnahmen (krinko ) nicht ersetzen kann (also kein ausgleich für unzureichende hygiene ist), sondern lediglich einen mosaikstein im gesamtkonzept aller maßnahmen zur vermeidung postoperativer wundinfektionen darstellt. die indikation zur prophylaxe ergibt sich aus der wundklassifikation nach cruse, (› tab. . ) und zusätzlichen risikofaktoren (› tab. . ). demnach ist bei sauberen eingriffen eine prophylaxe nur dann indiziert, wenn ein zusätzlicher risikofaktor vorliegt (› tab. . ) . bei sauber-kontaminierten oder kontaminierten eingriffen besteht in jedem fall eine indikation für die pap, bei schmutzigen eingriffen ist eine einmalige prophylaxe nicht ausreichend, hier sollte eine antibiotikatherapie durchgeführt werden. da in einzelfällen die indikation derzeit noch nicht geklärt ist und auch regionale faktoren eine rolle spielen, wird empfohlen, dass ein interdisziplinäres team in der jeweiligen klinik/abteilung die indikationsgruppen für die pap festlegt und jährlich überprüft. dabei sind wundinfektionsraten und das lokale erreger-und resistenzspektrum bei den ssi zu berücksichtigen. das therapeutische fenster, in dem die prophylaxe sinnvoll ist, reicht von stunde vor bis h nach hautschnitt. der ideale zeitpunkt liegt bei - min vor beginn der operation und sollte demnach am besten im rahmen der narkoseeinleitung durch den anästhesisten erfolgen. die gabe wird durch die abfrage der inzwischen nahezu flächendeckend etablierten op-checklisten im sogenannten ("team time out") überprüft. ein sonderfall ergibt sich beim (selten erforderlichen) gezielten einsatz von glykopeptiden (vancomycin oder teicoplanin) zur pap bei patienten, die mit mrsa kolonisiert sind (bratzler ) . vancomycin soll zur besseren verträglichkeit über mindestens eine stunde verabreicht werden. demnach muss mit der präoperativen infusion bereits h vor der op begonnen werden. wegen des schmalen wirkspektrums und der schlechteren wirksamkeit gegen über methicillin-sensiblen s. aureus sollten die glykopeptide nur zusätzlich zur standard-pap gegeben werden (bull, worth, richards ; cranny et al erstaunlicherweise zeigte die prävalenzstudie von , dass die antibiotikaprophylaxe in über % der fälle über den ersten tag hinaus angewandt wurde. in zusammenhang mit einem signifikanten anstieg der c.-difficile-assoziierten erkrankungen (cdad) und zunehmenden resistenzen insbesondere bei den gramnegativen infektionserregern ist eine solche quote inakzeptabel. hochgerechnet könnten in deutschland allein tonnen antibiotika pro jahr eingespart werden, wenn die postoperative "verlängerung" der prophylaxe ausbliebe. die auswahl des antibiotikums richtet sich nach dem erwarteten erregerspektrum. insbesondere muss unterschieden werden, ob eher eine infektion durch hautflora am wahrscheinlichsten ist (v. a. staphylokokken, z. b. bei implantaten in der traumatologie/orthopädie) oder infektionen durch enterobacteriaceae auftreten können (z. b. elektive colonchirurgie). im letzteren fall sollte das zur pap verwendete antibiotikum auch gegen anaerobier wirksam sein. wenn diese durch das eigentliche antibiotikum der wahl nicht erfasst sind (z. b. bei den cephalosporinen), kann diese lücke problemlos durch hinzunahme von metronidazol geschlossen werden. bei verwendung von ampicillin-sulbactam oder amoxicillin-clavulansäure zur pap ist die zusätzliche gabe von metronidazol nicht erforderlich. folgende weitere kriterien sollten bei der wahl des antibiotikums berücksichtigt werden: lokale erreger und resistenzsituation: hier gibt es regional teilweise dramatische unterschiede, die eine allgemeingültige empfehlung im rahmen dieses beitrags verhindern. wirksamkeit des präparats: in einigen richtlinien findet sich noch die empfehlung, zur pap substanzen zu verwenden, die nicht in der therapie zum einsatz kommen. in einigen fällen führt dies dazu, dass bei der prophylaxe substanzen verwendet werden, die aufgrund unbefriedigender resistenzlage nicht mehr zur therapie verwendet werden. die autoren sind der ansicht, dass eine infektionspräventive maßnahme nur dann sinnvoll ist, wenn sie wirksam ist. entsprechend muss das präparat gewählt werden. operationsgebiet: bei einigen richtlinien wird die wahl des antibiotikums im rahmen der prophylaxe abhängig gemacht vom operationsgebiet. so werden untergruppen gebildet wie magen-, Ösophagus-, pankreas-, leber-, oder darmchirurgie. die antibiotika, die dann empfohlen werden, unterscheiden sich in den meisten fällen nicht. darüber hinaus ist festzustellen, dass die umsetzung einer empfehlung unmittelbar mit der komplexität korreliert. empfehlungen zur pap sollten übersichtlich und eingängig sein und sich auf ein möglichst schmales spektrum von geeigneten antibiotika beziehen. gemäß empfehlung der peg sind folgende präparate bei der pap in der viszeralchirurgie mittels studien untersucht und sinnvoll: • cephalosporine der gruppe ii + metronidazol • cephalosporine der gruppe iii a + metronidazol • aminopenicilline mit betalaktamaseinhibitor • fluorchinolone der gruppe / + metronidazol es wird darauf hingewiesen, dass die resistenzen bei e. coli (leiterreger der infektionen mit enterobacteriaceae) gegenüber ampicillin/sulbactam in zahlreichen regionen so weit angestiegen ist, dass dort eine verwendung zur prophylaxe nicht mehr vertreten werden kann. ersatzpräparate bei allergien: bei allergien gegen penicilline können unter berücksichtigung der resistenzlage cephalosporine der . (z. b. cefuroxim) oder . generation (z. b. ceftriaxon) oder fluorchinolone der gruppe / jeweils kombiniert mit metronidazol eingesetzt werden. zu erfassendes erregerspektrum: die hauptverursacher von wundinfektionen in der viszeralchirurgie sind enterobacteriaceae (e. coli > klebsiella spp. > pseudomonas aeruginosa > proteus spp.). dies deutet darauf hin, dass der ursprung der wundinfektion bei diesen patienten "aus der tiefe" kommt (d. h. endogen verursacht ist), entweder durch intraoperative kontamination, postoperative translokation oder durch fortleitung eines okkulten intraabdominellen infekts (z. b. abszess) und nicht durch unzureichende hygiene bei der postoperativen wundpflege, wie häufig ver- mutet wird. in der traumatologie sind eher kommensalen der hautflora zu finden wie koagulase-negative staphylokokken (kns), ggf. auch s. aureus mit oder ohne methicillin-resistenz. substanzwahl bei vitien: meistens lässt sich die indikation für die endokarditisprophylaxe problemlos mit der antibiotikaprophylaxe durch verwendung eines geeigneten antibiotikums kombinieren. hier wird auf die diesbezüglichen empfehlungen der fachgesellschaften verwiesen. wird bei einem patienten bereits eine antibiotikatherapie mit entsprechendem wirkspektrum durchgeführt, kann von ausreichenden wirkspiegeln ausgegangen werden, sodass eine zusätzliche pap bei diesen patienten in der regel nicht erforderlich ist. in der vergangenheit konnte gezeigt werden, dass die standardisierte durchführung der pap die postoperative wundinfektionsrate senken kann. die pap ist als eine maßnahme im katalog der infektvermeidung anzusehen und ersetzt nicht weitere erforderliche maßnahmen. häufiges problem ist die zeitgerechte anwendung - min vor hautschnitt, da hier mehrere operationsvorbereitende maßnahmen gleichzeitig ablaufen müssen. in einer exakten interdisziplinären festlegung des präoperativen ablaufs soll auch die zuständigkeiten für die pap eindeutig geregelt sein. ein lösungsansatz besteht in der verwendung präoperativer checklisten, wie sie auch von der weltgesundheitsorganisation (who) ausgearbeitet und empfohlen wurden. essenziell erscheint es, die ungerechtfertigte verlängerung der antibiotikaprophylaxe über den operationstag hinaus in zukunft zu verhindern. peter hinz, axel kramer, matthias frank und axel ekkernkamp die ssi-rate wird für geschlossene frakturen mit - % angegeben und erreicht bei offenen frakturen abhängig vom ausmaß der gewebezerstörung eine häufigkeit von bis zu %. elektive unfallchirurgische eingriffe zeigen mit bis zu % eine deutlich geringere ssi-rate (seifert et al. (seifert et al. bisswunden › kap. . . . analog wie in der chirurgie ergibt sich die indikation für die pap aus der wundklassifikation und zusätzlichen risikofaktoren (› kap. . . ) . die parenterale single-shot-pap ist indiziert und präventiv wirksam bei sauber-kontaminierten oder kontaminierten eingriffen. bei sauberen eingriffen wird die pap bei folgenden risikoeingriffen empfohlen: osteosynthesen, hep und kep, rückenmarkchirurgie sowie offene reposition und interne fixation von frakturen (prokuski ) . in der cochrane-analyse von gosselini, roberts und gillepsie ( ) die pap ist grundsätzlich bei offenen frakturen indiziert (gosselini, roberts und gillepsie ) . dauer der pap: gegenstand von analysen ist in der versorgung offener frakturen v. a. die frage einmalige pap oder verlängerte postoperative behandlung, da letztere oft noch als standard angesehen wird . hauser, adams und eachempati ( ) gelangten im ergebnis einer metanalyse zu folgenden schlussfolgerungen: • "die aktuellen pap-standards bei offenen frakturen der röhrenknochen basieren nur auf sehr wenig und in manchen fällen gar keiner evidenz." • "das infektionsrisiko wird durch die kurzzeitige gabe eines cephalosporins der . generation möglichst früh nach der verletzung signifikant gesenkt, sofern gleichzeitig ein modernes orthopädisches fraktur-und wundmanagement erfolgt." diese aussagen werden durch folgende rcts bestätigt. bei offenen frakturen der grade und ergab sich kein signifikanter unterschied zwischen der ssi-rate. sie lag bei einmaliger gabe von mg perfloxacin i. v. bei , % und bei verlängerter gabe von cefazolin über d ( × g/d, gesamtdosis g) gefolgt von oxacillin über d oral bei % ( g/d; carsenti-etesse et al. ). im ergebnis einer weiteren metaanalyse konnte auch bei geschlossenen frakturen der röhrenknochen keine Überlegenheit einer mehrfachgabe im vergleich zur single-shot-strategie nachgewiesen werden (slobogean et al. ). zur auswahl der antibiotika ist die studienlage nicht eindeutig. in einer rct betrug die ssi rate bei frakturen grad nach pap mit ciprofloxacin % und nach pap mit cefamandol (betalaktamasestabiles cephalosporin der . generation) und gentamicin , %. dieser unterschied zeigt aufgrund der kleinen stichprobengröße nur einen trend (p = , ). dagegen zeichnete sich bei den frakturen grad und mit einer ssi-rate von , % bzw. % kein unterschied ab (patzakis et al. bei hep und kep wird durch die pap im ergebnis zurückliegender und neuerer studien einschließlich einer metaanalyse eine hochsignifikante reduktion von ssi erzielt (al buhairan, hind und hutchinson ; henley et al. ; hsu und cheng ; kuper und rosenstein ; lidwell et al. ) . entscheidend ist die einhaltung des zeitpunkts der pap, was leider häufig nicht gewährleistet ist (bateman, smith und grimer ; bhattacharyya und hooper ) . die prophylaktische wirkung antibiotika-freisetzender pmma (polymethylmethacrylat)-knochenzemente hinsichtlich der entstehung periprothetischer infektionen wurde in skandinavischen prothesenregistern sowie in metaanalysen überzeugend nachgewiesen ) mit einer herabsetzung der ssi rate bei primärer hep um durchschnittlich % gesenkt (parvizi et al. im unterschied zur konventionellen hep ergab sich bei endoprothetischer rekonstruktion nach tumorresektion im ergebnis einer retrospektiven analyse bei verlängerter antibiotikaprophylaxe (im mittel , d) eine geringere ssi-rate als bei single-shot (hettwer et al. ) , womit der trend einer metanalyse bestätigt wird (racano et al. ) . hierbei ist zu berücksichtigen, dass bei diesen eingriffen ein deutlich erhöhtes ssi-risiko (ca. %) besteht und die ssi in bis zu % die amputation der extremität zur folge haben kann (hettwer et al. ) . aussagekräftige prospektive randomisierte studien liegen jedoch zu dieser frage bisher nicht vor. im unterschied zu den usa (de beer et al. ; fletcher et al. ; kuong et al. ; meehan, jamali und nguyen ) und deutschland wird die pap in den niederlanden bei hep nur bei patienten mit eingeschränkter immunabwehr durchgeführt (abraham- inpijn. inpijn. ). wurde aus der schweiz berichtet, dass bei hep ein ersatz der pap durch intraoperative antiseptische spülung im operationsgebiet mit polihexanid mit gleicher ssi-rate möglich ist (kramer und willenegger ) . auswahl der antibiotika: als antibiotika für die pap werden cefazolin oder cefuroxim empfohlen (bratzler et al. ; sign ) . clindamycin und vancomycin kommen bei einer allergie gegen betalaktame in betracht (fletcher et al. ). sofern im ergebnis eines präoperativen screenings eine kolonisation mit mrsa festgestellt wurde und die mrsa-dekolonisation nicht abgewartet werden kann, muss zusätzlich ein gegen mrsa wirksames antibiotikum ausgewählt werden. bei vancomycin ist zu beachten, dass der wirksame spiegel erst nach h gewährleistet ist. da sich die resistenzlage fortlaufend ändert und je nach lokaler resistenzlage ein zunehmender anteil von ssi z. b. durch cefazolin-resistente staphylokokken verursacht wird, muss der auswahl des antibiotikums für die pap durch eine regelmäßige interdisziplinäre Überprüfung des hausinternen standards rechnung getragen werden (norton et al. ). dies ist ein wichtiger bestandteil eines antibiotic-stewardship-programms. nicht traumatisch bedingte neurochirurgische operationen zählen zu den primär sauberen bzw. sauber-kontaminierten eingriffen. transsphenoidale zugangswege gelten als primär kontaminiert. postoperative wundinfektionen (ssi) sind insgesamt in der neurochirurgie selten ( , - %; › tab. . ) , jedoch -wenn sie auftreten -mit hoher morbidität, letalität und einem verlängerten krankenhausaufenthalt verbunden (› kap. . ). postoperative bakterielle meningitiden sind als spezielle komplikation nach neurochirurgischen eingriffen besonders gefürchtet. neben der physiologischen hautflora des patienten, die vorwiegend aus koagulasenegativen staphylokokken (kns) besteht und als hauptreservoir für postoperative wundinfektionen gilt, können die erreger von der kopfbehaarung stammen oder über kontaminierte instrumentarien und implantate in das op-gebiet gelangen. das bei neurochirurgischen ssi zu erwartende erregerspektrum umfasst vor allem staphylokokken (s. aureus, kns), deutlich seltener p. acnes (insbesondere bei shuntoperationen und in der wirbelsäulenchirurgie) sowie streptokokken der viridansgruppe. in - % werden enterobakterien, sehr selten auch p aeruginosa oder andere nonfermenter nachgewiesen (z. b. a. baumannii) . bei hirnabszessen finden sich häufig mischinfektionen (felsenstein ; mishra ). die wichtigsten erreger sind mikroorganismen der oropharyngealen flora (und der nasennebenhöhlen) wie streptokokken der viridansgruppe, angeführt von s. milleri. tab. . wundinfektionsrate ohne perioperative antibiotikaprophylaxe (petrica et al . ) kraniotomie, wirbelsäulenchirurgie - liquorfistel stellenwert der perioperativen antibiotikaprophylaxe (pap) die pap wird in der neurochirurgischen literatur kontrovers diskutiert. sie wird vor allem zur prävention der postoperativen wundinfektion eingesetzt (› tab. . ) , deren inzidenz sich mit einer pap um etwa % reduzieren lässt. im unterschied zu einer publizierten metaanalyse (barker et al. ) fanden andere studien keinen signifikanten einfluss der pap auf die rate postoperativer meningitiden, die mit und ohne pap , bzw. , % beträgt (barker ; korinek et al. ; ratilal et al. ; sharma et al. ). als eindeutige indikationen gelten aseptische implantationen von fremdkörpern, z. b. eines vp-shunts (prusseit et al. ) oder einer subkutanen baclofen-pumpe (motta und antonello ), eingriffe mit langen op-zeiten (> - stunden) offene traumata sowie rezidivoperationen innerhalb von tagen nach der erst-op. die pap ist nur eine von zahlreichen weiteren maßnahmen der perioperativen infektionsprophylaxe (krinko ; kubilay et al. ; prusseit ). zum beispiel senkt ein wechsel der sterilen op-handschuhe, bevor der ventrikelkatheter erstmals berührt und implantiert wird, das infektionsrisiko bei shunt-operationen (rehmann et al. ) . für die wirbelsäulenchirurgie gibt es eine eigene leitlinie amerikanischer fachgesellschaften (watters et al. ); hier kann bereits der einsatz minimalinvasiver op-methoden das ssi-risiko um den faktor reduzieren (o'toole et al. ). risikofaktoren für ssi (korinek et al . ; lietard et al . ) liquorfistel ja ja externe ventrikeldrainage ja ja gleichzeitige wundinfektion -ja männliches geschlecht -ja frühzeitige reoperation ja - bei neurochirurgischen eingriffen wird die präoperative einmalgabe (single-shot-gabe) der antibiotika favorisiert. betalaktame (z. b. cefazolin, cefuroxim oder ampicillin-sulbactam, in ausnahmefällen auch piperacillin/tazobactam und teicoplanin) werden in den letzten min vor der op gegeben, vancomycin min vorher, weil es über mind. eine stunde infundiert werden muss (bratzler et al. ; scottish intercollegiate guidelines network ). flucloxacillin, cefazolin oder cefuroxim sind mittel der . wahl, clindamycin oder vancomycin sind alternativen bei allergie gegen β-lactam-antibiotika. bei vorliegen eines erhöhten anteils von mrsa bzw. von methicllin-resistenten kns an allen postneurochirurgischen wundinfektionen kann der zusätzliche einsatz von glykopeptiden wie vancomycin oder teicoplanin zur pap erwogen werden. alle genannten antibiotika können, z. b. bei implantaten, mit rifampicin kombiniert werden, ob dies einen signifikanten zusätzlichen nutzen hat, ist unklar. je nach dauer der op muss eine zweite gabe des antibiotikums verabreicht werden (cefazolin h, cefuroxim h, ampicillin-sulbactam h, piperacillin-tazobactam h, clindamycin h, vancomycin h) (bratzler et al. ) ; dies gilt z. b. auch bei erheblichem intraoperativem blutverlust. bei vp-shunt-operationen und neurochirurgischen eingriffen bei tumorpatienten kann die pap auf maximal gaben in stunden ausgedehnt werden, eine darüber hinaus verlängerte antibiotikagabe bringt jedoch definitiv keinen vorteil (bratzler et al. ; rath, costa und sampaio ) . patienten mit einer passageren ventrikelsonde (externer ventrikeldrainage; evd), die z. b. zur druckentlastung, zum invasiven monitoring des hirndrucks (hierzu gibt es auch spezielle, ebenfalls invasive drucksonden) oder als passagere lösung bei patienten mit vp-shunt-infektion (nach explantation desselben) eingesetzt wird, haben ein substanzielles risiko für eine menigoventrikulitis. scheithauer et al. ( ) fanden eine inzidenzrate von , / anwendungstage bei evd. diese patienten erhalten in der praxis häufig nicht nur vor der anlage der evd (leverstein-van hall et al. ) , sondern solange die drainage liegt, eine systemische antibiotikaprophylaxe, mit dem ziel, eine evd-assoziierte infektion zu verhindern. dieses vorgehen wird vor dem hintergrund unzureichender daten kontrovers diskutiert (bratzler et al. ; scottish intercollegiate guidelines network ) und von den meisten klinischen infektiologen abgelehnt (mc-carthy et al. ) . gerade bei der anwendung dieser devices ist ein streng aseptisches vorgehen nach einem für alle verbindlichen schriftlich festgelegten standard wichtig (camacho et al. ; kubilay et al. ; leverstein-van hall ; lwin et al. ). die lokoregionäre anwendung von antibiotika wird von einzelnen neurochirurgen favorisiert, ihre wirksamkeit ist jedoch bis heute unbewiesen (alves und godoy ). in einer kleinen prospektiven, doppelblind randomisierten studie konnten rozzelle, leonardo und li ( ) zeigen, dass die ssi-rate nach neurochirurgischen shunt-operationen bei verwendung von mit triclosan imprägniertem chirurgischem nahtmaterial niedriger war ( , % vs. %), wobei die ssi-rate in der kontrollkruppe in dieser studie sehr hoch ist. zur endgültigen bewertung des klinischen vorteils von antimikrobiell imprägnierten nahtmaterial fehlen in der neurochirurgie größere bestätigungsstudien. in einer prospektiv randomisierten studie an neurochirurgischen kliniken konnte der einsatz von minocyclin/rifampicin-imprägnierten drainagen (n = ) das risiko der evd-assoziierten meningoradikulitis senken (rate positiver liquorkulturen , vs. , %, p = , (zabramski et al. ) ). inzwischen werden vermehrt vp-shunts mit rifampicin-clindamycin imprägnierung implantiert (govender, nathoo und van dellen ) von denen die genannten antibiotika nach angaben der herstellers tage lang freigesetzt werden. für den endgültigen nachweis einer signifikant reduzierten ssi-rate (hier v. a. vp-shunt-assoziierte infektionen) stehen jedoch auch hier randomisierte, prospektive multicenterstudien aus (gutiérrez-gonzález und boto ) . vereinzelt wurde über nachfolgende infektionen mit rifampicin-resistenten kns berichtet (demetriades und bassi ). wong et al. ( fanden bei patienten mit externer ventrikeldrainage (evd), dass der rifampicin-clindamycin imprägnierte katheter (als evd) einer systemischen antibiotikaprophylaxe in bezug auf den endpunkt der device-assoziierten meningitis nicht unterlegen war. bei den postoperativen wundinfektionen im bereich der eintrittsstelle gab es keinen signifikanten unterschied (wong et al. ). auch pople et al. konnten bei sehr niedrigen infektionsraten in beiden gruppen ( , % vs. , %) keinen vorteil des rifampicin-clindamycin-imprägnierten katheters gegenüber nicht imprägnierten externen ventrikeldrainagen darstellen (pople et al. ) bilal al-nawas invasive eingriffe und vergleichbare maßnahmen, z. t. sogar operationen, werden meist handelt es sich in der zahnmedizin und mkg-chirurgie um eingriffe der gruppen ii und iii, wobei ssi überwiegend durch oropharyngeale pathogene verursacht werden. grundsätzlich kann unterschieden werden zwischen der pap zur vermeidung der negativen folgen einer bakteriämie, wie sie patienten mit gelenkendoprothesen oder endokarditisrisiko betreffen kann, und der prophylaxe von ssi im engeren sinn. auch wenn die antibiotika bezüglich der infrage kommenden erreger oft identisch sind, besteht der unterschied in der konsequenz bei auftreten von problemen. so lässt sich die lokal begrenzte ssi meist gut beherrschen, während eine endokarditis per se vital bedrohlich ist. es empfiehlt sich also, für die indikationsfindung das individuelle risikoprofil des patienten zu grunde zu legen. im vergleich zur humanmedizin finden sich keine systematischen daten zur resistenzentwicklung in der zahnmedizin. berichtet wurde bei unkomplizierten abszessen über geringe resistenzraten für penicillin (eckert et al. a ), aber auch über das auftreten von - % betalaktamasen bei bakterien aus odontogenen abszessen (kuriyama et al. kuriyama et al. ) . bei schweren weichgewebeinfektionen, die typischerweise schon vorbehandelt sind, muss man demnach mit einer höheren resistenzrate gegen penicillin und clindamycin rechnen eckert et al. b ). aus den vorgenannten daten ergibt sich im odontogenen bereich eine nahezu vollständige wirksamkeit der kombination aus einem aminopenicillin mit einem betalaktamasehemmer (amoxicillin-clavulansäure oder ampicillin-sulbactam). bei der resistenzbeurteilung sollte jedoch bedacht werden, dass die pathogenetische rolle der identifizierten bakterien durchaus nicht geklärt ist (otten et al. ). da ein erregernachweis in der therapie unkomplizierter odontogener infektionen nicht praktikabel ist, bleibt der wunsch nach validen resistenzdaten in der ambulanten zahnmedizin wohl auch in zukunft unerfüllt. indikationen für die prophylaktische antibiotikagabe bzw. pap indikationen: grundsätzlich ist akzeptiert, dass bakteriämien bei vorgeschädigtem endokard zu einer infektiösen endokarditis führen können. zugleich ist unbestritten, dass bei allen zahnärztlichen behandlungen mit manipulation an der gingiva und bei wurzelka-nalbehandlungen bakteriämien auftreten. aber auch bei routineaktivitäten wie zähneputzen oder kauen sind bakterien im blut nachweisbar. beachtenswert ist, dass im tiermodell - log bakterien/ml blut zur auslösung einer endokarditis erforderlich sind (bahn et al. ) , bei zahnärztlichen behandlungen findet man jedoch nur - /ml (rahn et al. ) . in einer richtungweisenden arbeit aus frankreich wurde die effektivität der antibiotikaprophylaxe infrage gestellt (duval et al. ) . seitdem hat sich ein paradigmenwechel vollzogen (naber et al. ). demnach sollen nicht mehr alle patienten mit dem risiko für eine infektiöse endokarditis eine prophylaxe erhalten, sondern nur patienten mit einem hohen erkrankungsrisiko oder einem hohen risiko für einen lebensbedrohlichen verlauf. die auswahl der antibiotika bleibt dagegen unverändert entsprechend den erwarteten oralen pathogenen. für patienten, die bisher eine prophylaxe erhielten und bei denen diese jetzt nicht mehr indiziert ist, gibt es die möglichkeit der individuellen, fakultativen prophylaxe. als risikoprozeduren werden alle eingriffe angesehen, die zu bakteriämien führen können wie manipulationen an der gingiva, der periapikalen zahnregion, perforationen der oralen mukosa. aktuelle daten deuten darauf hin, dass diese gelockerten leitlinien nicht zu einem anstieg der endokarditisinzidenz geführt haben (desimone et al. ). die einschätzung der prophylaxe von infektionen von endoprothesen ist schwierig. jüngere metaanalysen der spärlichen literatur stellen den sinn dieser prophylaxe bei gesunden patienten infrage (legout et al. ) , zumal infektionen von hüft-oder knieendoprothesen als folge von bakteriämien nach oralen eingriffen sehr selten sind (rodgers und richards ) . als gute handlungsgrundlage existiert eine methodisch sehr hochwertige interdisziplinäre leitlinie zur prophylaxe aus den usa (watters et al. ) , in der die indikation zur prophylaxe kritisch bewertet und die bedeutung der mundhygiene betont wird es besteht konsens, dass für die meisten zahnärztlichen eingriffe bei gesunden patienten keine antibiotikaprophylaxe erforderlich ist (al-nawas ), z. b. im rahmen der endodontie (mohammadi ) und in der einfachen dentoalveolären chirurgie bei gesunden patienten (al-nawas ). im gegensatz zur einfachen zahnextraktion wird die pap vor weisheitszahnextraktion (kontaminiertes gebiet gr. iii) auf der basis von studien an über patienten empfohlen (ren und malmstrom ) . es bestätigte sich, dass die prolongierte prophylaxe keinen zusätzlichen effekt zeigte, wohl aber konnte der negative effekt einer zu späten, ausschließlich postoperativen gabe bestätigt werden. bei der insertion dentaler implantate (sauber-kontaminiertes gebiet gr. ii) sank die implantatverlustrate bei pap in einer meta-analyse um , % (al-nawas und stein ). um diesen effekt zu erreichen, muss jedoch eine hohe anzahl an patienten eine prophylaxe erhalten (number needed to treat ). ein aktueller cochrane review zu diesem thema bewertet den nutzen einer pap bei der implantatinsertion positiv (esposito et al. ) . unbestritten ist bei komplexen implantologischen eingriffen, wie z. b. augmentationen eine pap sinnvoll. auswahl der antibiotika: zur pap empfehlen die meisten autoren penicillin v oder amoxicillin. in hinblick auf gewebespiegel scheint konsens zu bestehen, dass zur prophylaxe eine etwas höhere dosierung (z. b. - g amoxicillin p. o. als einmalgabe) sinnvoll erscheint und zwar vor dem eingriff (steinberg et al. ). daher empfiehlt sich, die pap bei der planung ambulanter eingriffe mit dem patienten vorzubereiten. die prolongierte postoperative gabe hat bei einfachen invasiven eingriffen keinen einfluss auf die ssi-rate. immunsupprimierte patienten (z. b. nach radiatio oder bisphosphonattherapie) profitzieren hingegen von einer prolongierten prophylaxe über mehrere tage (grötz ) . bei den meist komplexen ops im (sauber-)kontaminierten gebiet wird fast durchgängig die pap empfohlen, z. b. zur versorgung frakturierter gesichtsknochen (knepil und loukota ) und für die lappenchirurgie (amland et al. ) . bei unterkieferfrakturen wird nicht nur die einmalgabe, sondern eine eintägige gabe diskutiert (andreasen et al. ); interessanterweise wird das durch daten der kieferorthopädischen chirurgie gestützt (danda et al. ). deutlich weniger daten liegen für die chirurgie der lippen-, kieferund gaumenspalten vor; dennoch empfehlen die meisten autoren auch hier zumindest die pap (smyth & knepil ) . bei komplexen ops im sauberen gebiet (gr. i) wird eine stündige gabe empfohlen; z. b. für die neck dissection (seven, sayin und turgut ) . eine pap über mehr als stunden (drei gaben) ist bei sauber-kontaminierten operationen (gr. ii), analog zu daten aus anderen chirurgischen fächern, ohne messbaren effekt und sollte daher vermieden werden (mottini et al. ). gemäß ifsg ( § ) sind leiter von einrichtungen für ambulantes operieren verpflichtet, ni fortlaufend aufzuzeichnen und zu bewerten. allerdings bezieht sich der begriff ambulantes operieren auf operationen ( § sgb v) und nicht auf invasive (zahnärztliche) eingriffe. grundsätzlich ist die qualitätssicherung und Überwachung der eigenen infektionsraten zu fordern, die systematische prospektive Überwachung ist für eingriffe in der kontaminierten mundhöhle jedoch nicht praktikabel. zugleich muss die resistenzentwicklung von den verschreibenden kritisch beobachtet und ein wissenschaftlich nicht gesicherter antibiotikaeinsatz kritisch hinterfragt werden. in allen empfehlungen stellen penicilline die zentrale säule der in der zahnmedizin verwendeten substanzen dar. die verbreitung von mre wird durch ungezielte antibiotikagaben in therapie und prophylaxe gefördert. deswegen ist die streng indizierte pap bei einhaltung aller hygienischen maßnahmen eine wichtige maßnahme zur minderung der resistenzentwicklung. ziel der pap ist die vermeidung von ssi, idealerweise ohne wesentliche beeinträchtigung der normalflora oder induktion eines selektionsdrucks mit der gefahr der ausbildung von antibiotikaresistenzen (peters ) . die pap ist kein ersatz für hygienemaßnahmen zur prävention von ssi! gesicherte indikationen im hno-bereich sind tumorchirurgische eingriffe mit eröffnung der schleimhäute von mundhöhle/ pharynx und/oder larynx (johnson, myers und sigler ; liu, tung und chiu ) sowie gesichtsfrakturen, insbesondere komplizierte unterkieferfrakturen (bratzler et al. ; sign ) . daneben gibt es akzeptierte indikationen (einbringen von implantaten) wie die kochlearimplantchirurgie. für zahlreiche hno-ärztliche eingriffe der ohr-, nasen-, nasennebenhöhlenchirurgie ist der nutzen einer pap noch ungeklärt! galt eine > stunden liegende nasentamponade als indikation für eine u. u. mehrtägige (ungezielte) antibiotische "prophylaxe" (therapie), zeigen neuere arbeiten keinen vorteil (biswas und mal in der gynäkologie handelt es sich meist um elektive eingriffe (ausnahmen z. b. akuter unterbauchschmerz, stielgedrehtes ovar, extrauterine gravidität; geburtshilfe: eilige bzw. notfallsektio). neben ambulanter op-vorbereitung und möglichst kurzer krankenhausverweildauer sollten prätherapeutisch vorhandene infektionen wie atemwegs-, harnwegsinfektionen oder infektionen äußerer oder innerer genitalorgane saniert werden. ebenso wichtig sind die internistische abklärung der operabilität, die optimale einstellung eines diabetes mellitus, die stabilisierung von herz-kreislauf-parametern sowie der hämoglobin-und elektrolytausgleich. andere risikofaktoren wie alter, organspezifische komorbiditäten, durchblutungsstörungen, adipositas oder insbesondere ihre kombinationen sind u. u. nicht präoperativ optimierbar. bei vorhandenen und nicht abwendbaren risikofaktoren (asa-kriterien) sollten ggf. konservative therapieoptionen (z. b. bestrahlung von tumoren, primäre chemo-oder antihormontherapie) bzw. eine möglichst kurze op-zeit mit einschränkung der radikalität der op überdacht werden. bei onkochirurgischen, häufig multiviszeralen operationen (insbesondere ovarialkarzinom, darmbeteiligung) erfolgt präoperativ die vollständige darmentleerung. bei kleineren abdominalen eingriffen ist die säuberung des enddarms ausreichend (makroklistier). vorhandene piercings sind präoperativ zu entfernen. rasieren ist nur bei op-technischer notwendigkeit unmittelbar präoperativ durchzuführen. zur verringerung von ssi gehört insbesondere bei vaginalen eingriffen die gründliche reinigung und antiseptik der mikrobiell belasteten anogenitalregion bzw. der bauch-und thoraxwand/ axilla bei abdominalen und mammachirurgischen eingriffen. hierbei ist insbesondere auf die ausreichende antiseptik von umbilikalregion, mamille und submammar-/axillarfalte zu achten. bei präpartalem vaginalem nachweis von streptokokken der sero gruppe b (gbs) sollte prophylaktisch -stündlich ab geburtsbeginn penicillin ( . wahl: ampicillin) i. v. verabreicht werden (bei penicillinallergie z. b. clindamycin) (dggh ) . auch bei drohender frühgeburt und fehlender gbs-testung wird eine prophylaktische antibiotikagabe empfohlen. die effektivität der gbs-prophylaxe ist eingeschränkt, wenn sie weniger als h vor der geburt begonnen wurde. die infektion des neugeborenen kann eine schwere allgemeininfektion mit pneumonie und schocksymptomatik bzw. neugeborenensepsis zur folge haben, wobei mit neurologischen langzeitschäden und einer letalität von % zu rechnen ist. ein gbs-screening ist daher in der schwangerschaft empfehlenswert. bei hiv infektion der werdenden mutter beträgt die transmissionsrate bis zu %. das risiko kann durch senkung der viruslast durch antiretrovirale medikation, ggf. primäre sectio, antiretrovirale pep des neugeborenen (oral zidovudin bis zu wochen) und stillverzicht auf < % gesenkt werden. daher sollte jeder schwangeren ein hiv-such-und ggf. hiv-bestätigungstest empfohlen werden. die Übertragung von hbv einer akut oder chronisch infizierten schwangeren erfolgt, abhängig von der höhe der viruslast, im letzten schwangerschaftsdrittel ( - %) bzw. während der geburt ( %) bzw. während des stillens ( %). die peripartale infektion der kindes verläuft oft asymptomatisch und geht in den meisten fällen in einen chronischen hbv-trägerstatus über (bis %); % der kinder sterben an den folgen (leberzirrhose, hepatozelluläres karzinom) (lam, gotsch und langan ) . die hbs-antigen-(mutterschaftsrichtlinien) bzw. antikörperbestimmung und weitere antigensuche im letzten schwangerschaftsdrittel ermöglichen die planung der primären sectio, eine frühzeitige aktive und passive immunisierung des neugeborenen (senkung des infektionsrisikos um % bei impfung innerhalb von h post partum). aktiv und passiv immunisierte neugeborene dürfen gestillt werden. die mutter-kind-transmissionsrate von hcv (prävalenz < %) ist gering ( - %) und durch sektio oder stillverzicht nicht weiter absenkbar (dgvs ) . ein screening bei abwesenheit von koinfektionen oder speziellen mütterlichen risikofaktoren wird in der schwangerschaft wegen fehlender suffizienter medikamentöser therapie nicht empfohlen. gesicherte risikofaktoren für frühgeburten und spätaborte sind bakterielle vaginose, aszendierende oder maternale infektionen (leitich und kiss (aus et al. ) . vorübergehende nebenwirkungen wie örtlicher schmerz, hämaturie, hämospermie, dysurie und rektale blutung werden häufig berichtet (crundwell, cooke und wallace ; djavan et al. ; loeb et al. ) . eine bakteriurie findet sich bei %- %, eine transiente bakteriämie bei bis zu % der patienten (lindert, kabalin und terris. ; thompson et al. ) . fieber in verbindung mit urogenitalen symptomen werden bei %- % und eine postinterventionelle sepsis bei bis zu % der patienten beschrieben (crawford et al. ; enlund und varenhorst ; lindert, kabalin und terris ; thompson et al. ) . die alleinige rektale instillation von pvp-iod zeigte in einer prospektiv randomisierten studie an männern nach trpb eine nichtsignifikante (wenn auch -prozentige) reduktion von infektiösen komplikationen gegenüber der unbehandelten gruppe (abughosh et al. ) . eine grundsätzlich andere strategie wäre der ersatz der ultraschall-gesteuerten trbp durch eine perineale prostatabiopsie (wagenlehner et al. ) , wobei sich auch hier die frage einer pap zur vermeidung von wundinfektionen stellte. durch die pap kann die inzidenz postinterventioneller infektiöser komplikationen nach trpb verringert werden (aron, rajeev und gupta ; aus et al. ; crawford et al. ; isen et al. ; kapoor et al. ; zani, clark und rodriguez netto ), weshalb die perioperative antibiotikaprophylaxe (pap) bei der transrektalen prostatabiopsie als standardvorgehen angesehen werden kann, sofern bestimmte voraussetzungen eingehalten werden. zeitpunkt, dauer und applikationsform der pap sind umstritten. eine metaanalyse der pap bei trpb ergab, dass eine verlängerte prophylaxe nicht wirksamer als die präinterventionelle einmalgabe ist (zani, clark und rodriguez netto ) ; dies wurde auch durch eine später publizierte literaturauswertung bestätigt (loeb et al. ) . unter welchen umständen eine einmalgabe erfolgreich bzw. nicht indiziert ist, wurde am besten in einer schwedischen studie (lindstedt et al. ) mit prostatabiopsien mit oraler einmalgabe von hochdosiertem ciprofloxacin ( mg) innerhalb h vor dem eingriff untersucht. mit dieser dosierung können ausreichend hohe urin-und prostatagewebekonzentrationen bis zu h aufrecht erhalten werden (naber, adam und kees ; naber ; wagenlehner und naber ) und in der genannten studie (lindstedt et al. ) lag die postinterventionelle infektionsrate bei etwa %, was im literaturvergleich niedrig ist (aron, rajeev und gupta ; aus et al. ; crawford et al. ; djavan et al. ; enlund und varenhorst ; isen et al. ; kapoor et al. ; raaijmakers et al. ) . für die präoperative einmalgabe kommen nur patienten infrage, bei denen zuvor eine harnwegsinfektion (hwi) und eine asymptomatische bakteriurie ausgeschlossen wurden und ferner keine der folgenden risikofaktoren vorliegen: • dauerkatheter wegen harnverhalt, • rezidivierende hwi, prostatitis oder andere fieberhafte genitalinfektion in der anamnese, • immunsuppression. zum ausschluss einer hwi/bakteriurie sollte innerhalb einer woche vor dem eingriff eine urinkultur aus mittelstrahlurin durchgeführt werden. als surrogatparameter kann alternativ auch ein urinstatus mit negativer leukozytenesterase und negativem nitrit im streifentest genutzt werden. nur ( , %) der auf diese weise voruntersuchten patienten entwickelte nach der trpb eine fieberhafte urogenitale infektion; davon mussten wegen einer schwerer infektion hospitalisiert werden. die sepsisrate lag bei , %. bei den patienten, bei denen entweder eine bakteriurie übersehen wurde oder sich trotz negativem urinstatus eine bakteriurie fand, entwickelte sich bei eine postinterventionelle symptomatische hwi, davon in fällen mit sepsis. diese rate ist deutlich höher als bei patienten mit sterilem urin, weshalb auch die asymptomatische bakteriurie als risikofaktor angesehen wird. die infektionsrate lag in etwa gleicher größenordnung wie bei transurethraler resektion der prostata (turp) bei patienten mit bakteriurie (grabe und hellsten ) . allerdings hätten von den patienten aufgrund von risikofaktoren von der antibiotika-einmalgabe ausgeschlossen werden müssen. die studie zeigt an einem großen patientenkollektiv, dass eine perioperative antibiotika-einmalgabe auch bei der trpb ausreichend ist, wenn zuvor eine bakteriurie durch urinkultur (oder zumindest durch einen negativen streifentest) weitgehend ausgeschlossen werden kann und keiner der genannten risikofaktoren vorliegt. auf die zusätzliche gabe eines gegen anaerobier-wirksamen antibiotikums wurde in der studie bewusst verzich-tet, obwohl in sehr seltenen fällen auch eine postinterventionelle infektion mit anaerobiern beschrieben worden ist (miura et al. ). die meisten untersuchungen zur wirksamkeit der pap bei trpb wurden mit fluorchinolonen (fch) zu einer zeit durchgeführt, als die prävalenz der fch-resistenz niedriger als heute war (zani, clark und rodriguez netto ) . die antibiotikaauswahl ist heute nicht mehr so leicht, da auch in deutschland bei gramnegativen erregern urogenitaler infektionen eine zunehmende resistenzentwicklung gegen fch zu beobachten ist (kresken, hafner und körber-irrgang ) . insofern erscheinen zuletzt häufiger berichte über patienten, die nach prophylaxe mit einem fch eine schwere postinterventionelle infektion bis hin zur sepsis verursacht durch einen fch-resistenten erreger (meist e. coli) erlitten haben (feliciano et al. ; miura et al. ; nam et al. ; shigehara et al. ; tal et al. ; wagenlehner et al. ; young, liss und szabo ) . die gastrointestinale kolonisation mit fch-resistenten e. coli prädisponiert für eine solche komplikation (roberts et al. ). da die prostatabiopsie in der regel transrektal erfolgt, genügt es nicht, lediglich durch eine urinkultur das vorhandensein fch-resistenter erreger in den harnwegen auszuschließen. ein zusätzlicher analabstrich ist hier wahrscheinlich von nutzen, wird jedoch bisher nicht regelmäßig durchgeführt (roberts et al. ; taylor et al. ) . bereits die prophylaktische einmalgabe eines fch kann die rate fch-resistenter e. coli in der fäkalflora deutlich erhöhen (wagenlehner et al. ) (medikamentenanamnese!). eine us-amerikanische untersuchung von patienten vor trpb, bei denen ein rektalabstrich auf selektivagar mit einer ciprofloxacin-konzentration von mg/l eingesetzt wurde, fand bei % der patienten ciprofloxacin-resistente coliforme bakterien ( % e. coli) (taylor et al. ) . risikofaktoren für diesen nachweis waren herzklappenersatz und die einnahme von ciprofloxacin innerhalb der letzten drei monate. in der gesamten kohorte erlitten ( , %) der patienten infektiöse komplikationen nach trpb, bei ( %) durch fluorchinolon-resistente coliforme bakterien. die inzidenz von infektionen in der gruppe mit präinterventionellem nachweis fch-resistenter e. coli lag bei % (taylor et al. ). diese daten zur pap bei trpb sprechen eindeutig dafür, bei patienten mit risikofaktoren fluorchinolone nur noch einzusetzen, wenn durch einen negativen rektalabstrich eine fäkale kolonisation mit fluorchinolon-resistenten coliformen bakterien ausgeschlossen wurde (wagenlehner et al. ). leider sind andere antibiotika in diesem kontext bisher nicht gut untersucht. zwar zeigte eine publizierte pap-studie für cotrimoxazol ähnlich gute ergebnisse wie für levofloxacin (wagenlehner et al. ) , in den meisten erhebungen (z. b. zur zystitis) liegt jedoch heute der anteil cotrimoxazol-resistenter e. coli über % (naber et al. ). infrage kämen demnach z. b. cephalosporine der . generation, z. b. ceftriaxon - g, oder piperacillin in kombination mit tazobactam (einzeldosis g/ , g); beide währen jedoch gegen einen esbl-bildendes isolat nicht bzw. nicht sicher wirksam (ozden et al. ). zu oralen betalaktamantibiotika fehlen entsprechende studien. die einmalgabe eines aminoglykosids (nur parenteral, z. b. amikacin) wurde ebenfalls bisher nicht an einem ausreichend großen patientenkollektiv untersucht, gentamicin war oral verabreichtem ciprofloxacin unterlegen (roach et al. ) . auch oral verabreichtes fosfomycin (als fosfomycin-trometamol; ft) wurde zur pap bei turp angewendet (di silverio, ferrone und carati ; periti et al. ) . fosfomycin hat den vorteil, dass fch-resistente, esbl-bildende e. coli nicht gleichermaßen häufig auch gegen fosfomycin resistent sind (keine parallelresistenz) (akyar ) . in einer retrospektiven auswertung des klinischen verlaufs bei patienten erhielten patienten g ft, patienten mg levofloxacin (einmalgabe) und patienten × mg/d ciprofloxacin mit beginn vor dem eingriff über d (ongün, aslan und avkan-oguz ). insgesamt entwickelten ( %) patienten eine fieberhafte hwi ( , % nach ciprofloxacin, , % nach levofloxacin und , % nach ft; unterschiede nicht signifikant). ausreichend abgesichert ist ft zur perioperativen prophylaxe bei trpb damit nicht. falls trotz antibiotikaprophylaxe eine schwere infektion auftritt, was nie vollständig zu vermeiden ist, muss in etwa % der fälle (feliciano et al. ) mit einem erreger gerechnet werden, der gegen das zur prophylaxe verwendete antibiotikum resistent ist. vor einleitung der empirischen therapie sollte eine urinkultur und -bei sepsiszeichen -auch mindestens eine blutkultur angelegt werden. empirisch sollte dann ein breitspektrumantibiotikum mit guter wirksamkeit gegen enterobacteriaceae aus einer anderen klasse (im vergleich zur pap) zur anwendung kommen. infrage kommt bei schweren infektionen z. b. piperacillin-tazobactam, ggf. auch in kombination mit amikacin bis ein erreger (und dessen in vitro empfindlichkeit) bekannt ist. besteht aufgrund der individuellen anamnese oder der örtlichen resistenzsituation der verdacht auf eine infektion durch einen esbl-bildendenden erreger ist (empirisch) ein carbapenem das mittel der ersten wahl. jörg ringel und markus m. lerch empfehlungen zur antibiotikaprophylaxe in der gastroenterologie beziehen sich im wesentlichen auf endoskopische eingriffe. dabei steht nicht mehr nur die endokarditisprophylaxe im vordergrund, sondern sollen insgesamt interventionsspezifische infektionsrisiken minimiert werden. daneben gibt es leitlinien bzw. studiendaten, die eine antibiotikaprophylaxe bei leberzirrhosepatienten und bei patienten mit pankreaspseudozysten in bestimmten situationen und vor bestimmten eingriffen empfehlen. es besteht keine generelle indikation zur endokarditisprophylaxe vor endoskopischen eingriffen. bei spezifischen patientengruppen mit besonderem risiko für eine endokarditis ist im rahmen unterschiedlicher endoskopischer prozeduren eine antibiotikaprophylaxe indiziert (› tab. . (allison et al. ; rosien ) . hochrisikopatienten, die in der vergangenheit eine antibiotikaprophylaxe gut vertragen haben, sollten über die neuen empfehlungen informiert werden und können in absprache mit dem behandelnden arzt weiterhin eine prophylaxe erhalten (rosien ) . unabhängig von der endokarditisprävention gibt es für einzelne endoskopische untersuchungsprozeduren in den leitlinien empfehlungen zur prophylaktischen antibiotikagabe (› tab. . ). das betrifft im rahmen einer endoskopischen retrograden cholangiopankreatikoskopie (ercp) patienten mit cholangitis, patienten, bei denen keine vollständige biliäre drainage erreichbar ist (z. b. bei primär sklerosierender cholangitis oder gallenwegneoplasie), sowie patienten bei z. n. lebertransplantation oder bei denen mit dem gallengangsystem kommunizierende pankreas-oder pseudozysten bestehen (allison et al. , rosien . bei schwerer neutropenie (< , × /l) und/oder fortgeschrittenen hämatologischen neoplasien wird bei untersuchungen mit erhöhtem bakteriämierisiko wie z. b. dilatationsbehandlung und sklerosierung eine antibiotikagabe empfohlen (allison et al. trotz teilweise widersprüchlicher daten empfehlen die internationalen leitlinien vor der anlage einer perkutanen endoskopischen gastrostomie (peg) unabhängig von der methode die einmalgabe eines antibiotikums (fadendurchzugmethode oder direktpunktion) (allison et al. ; rosien ) . bei leberzirrhosepatienten mit überwundener spontanbakteriel ler peritonitis (sbp) oder mit akuter gastrointestinaler blutung besteht die indikation zur antibiotikaprophylaxe. aufgrund zunehmender resistenzentwicklung sollten bestimmte risikokonstellationen beachtet werden. bei patienten mit leberzirrhose treten gehäuft bakterielle infektionen auf. sie können zu schwerwiegenden beeinträchtigungen der kardiopulmonalen, hepatischen und renalen funktion führen. die sbp stellt eine dieser schwerwiegenden komplikationen dar und ist mit deutlich erhöhter letalität assoziiert (alaniz und regal ; chavez-tapia et al. ; terg et al. (lee et al. ; terg et al. ). unter konsequenter diagnostik und sofortiger antibiotikatherapie konnte die letalität in den letzten jahren von etwa % auf - % gesenkt werden. die entscheidung darüber, welches antibiotikaregime empirisch bzw. kalkuliert eingesetzt werden soll, hängt davon ab, ob die infektion ambulant oder nosokomial erworben wurde (gerbes ). das rezidivrisiko liegt ersten jahr nach erfolgreicher behandlung der sbp bei etwa % (alaniz und regal ; chavez-tapia et al. ). deshalb wird in den leitlinien eine prophylaktische antibiotikagabe mit norfloxacin mg/d empfohlen. diese soll bis zur vollständigen aszitesrückbildung, bis zu einer lebertransplantation oder -wenn keines der beiden ziele erreicht wird -lebenslang durchgeführt werden. in diesem zusammenhang haben studien eine zunehmende resistenzentwicklung nachgewiesen, weshalb in der derzeit gültigen aszitesleitlinie eine zeitliche begrenzung empfohlen wird (gerbes ). eine nur einmal wöchentliche gabe hat sich als insuffizient herausgestellt (alaniz und regal ) . eine aktuelle studie konnte keinen vorteil hinsichtlich des auftretens einer sbp bei einer prophylaktischen gabe von rifaximin bei hospitalisierten patienten nachweisen (lutz ) eine erniedrigte aszitesproteinkonzentration (< , g/dl) wurde als risikofaktor für eine sbp ermittelt. deshalb untersuchten terg et al. ( ) die primärprophylaktische gabe von ciprofloxacin mg/d bei patienten mit erniedrigter aszitesproteinkonzentration, was zu einer reduzierten spb-rate und einer verringerten mor- talität in den folgenden -monaten führte (alaniz und regal ; terg et al. ). entsprechend der gültigen dgvs-leitlinie kann in diesem fall eine primäre antibiotikaprophylaxe durchgeführt werden. auch bei hochrisikopatienten mit zusätzlicher schwerer leberinsuffizienz (child-pugh score > ) und niereninsuffizienz (serumkreatinin > , mg/dl; harnstoff > mg/dl oder natrium < meq/l) besteht die empfehlung zur primären antibiotikaprophylaxe (gerbes ; runyon ; › tab. . ) . patienten mit leberzirrhose, die aufgrund gastrointestinaler blutung stationär aufgenommen werden, stellen eine weitere gruppe für eine antibiotikaprophylaxe dar. studien haben eine um bis zu % erhöhte infektionsinzidenz sowie ein deutlich erhöhtes rezidivblutungsrisiko gezeigt. deshalb ist die sofortige antibiotikagabe (noch vor der endoskopischen diagnostik) mit einem fluorchinolon oder einem cephalosporin der dritten generation für d indiziert (alaniz ; allison et al. ; gerbes ; rosien ). . . antibiotikaprophylaxe in der hämatologie/onkologie (erwachsene) hämatologisch-onkologische patienten können ein erhöhtes bis sehr hohes risiko für bakterielle infektionen haben, verursacht durch die erkrankung selbst und/oder als nebenwirkung der antineoplastischen therapie (donnelly, blijlevens und van der velden ; krinko ; wilson ) (› tab. . ) . der wichtigste risikofaktor für die akquisition bakterieller infektionen bei hämatologisch-onkologischen patienten ist die chemotherapie-assoziierte neutropenie (granulozytopenie). wenn eine absolute neutrophilenzahl von < /µl oder von < /µl mit innerhalb von d zu erwartendem abfall auf < /µl vorliegt, kann anhand der zu erwartenden dauer der neutropenie eine risikoklassifikation vorgenommen werden (› tab. . ) . die gefahr von infektionen ist noch höher, wenn praktisch keine granulozyten (granulozyten < µl) mehr nachweisbar sind (freifeld et al. ). eine noch übersichtlichere einteilung unterscheidet zwischen einer dauer der granulozytopenie von ≤ oder > tagen (neumann et al. die mediane dauer der granulozytopenie ist bei patienten nach hochdosistherapie und autologer stammzelltransplantation deutlich kürzer als bei allogener transplantation. eine antibiotikaprophylaxe wird in den jeweiligen behandlungsprotokollen jedoch meist ebenso empfohlen wie die gabe von granulozyten-stimulierendem faktor (g-csf) zur verkürzung der granulozytopenie (kiefer et al. ; montemurro et al. ). standard ist die gabe systemisch wirksamer fluorchinolone (fch; ciprofloxacin, levofloxacin). alternativ kann trimethoprim-sulfamethoxazol (tmp-smz, cotrimoxazol) eingesetzt werden. bei trimethoprim-sulfamethoxazol müssen resistente e. coli, die unzureichende pseudomonas-wirksamkeit, die schlechtere verträglichkeit (gastrointestinal, haut) und die verlängerte granulozytopeniedauer bei prolongierter täglicher einnahme bedacht werden. die orale gabe nicht resorbierbarer antibiotika (aminoglykoside und/oder polymyxin) ist in diesem klinischen kontext inzwischen obsolet. zur antibiotikaprophylaxe bei neutropenischen patienten gibt es umfangreiche studien und metaanalysen sowie leitlinien der fachgesellschaften (krüger et al. ; neumann et al. (imran et al. ; neumann et al. ) die prophylaktische antibiotikagabe ist mit einem nicht signifikant erhöhten auftreten von nebenwirkungen assoziiert, im ein-zelfall (sehr selten!) können fluorchinolone jedoch auch schwere unerwünschte ereignisse auslösen (z. b. lebertoxizität, neurotoxizität, achillessehnen-ruptur). ungünstige interaktionen mit der chemotherapie sind möglich (z. b. hepatotoxizität; alshammari et al. gegenwärtig gibt es keinen vollständigen internationalen konsensus zum einsatz von antibiotika zur prophylaxe bakterieller infektionen bei patienten mit chemotherapie-bedingter neutropenie, es liegen jedoch leitlinien der fachgesellschaft hierzu vor (krüger et al. ; neumann et al. ) . die arbeitsgemeinschaft infektionen in der hämatologie und onkologie (agiho) empfiehlt bei hochrisikopatienten (› tab. . ) und bei patienten unter allogener stammzelltransplantation die gabe von fch (krüger et al. ; neumann et al. ) . alternativ kann bei unverträglichkeit cotrimoxazol (tmp-smz) gegeben werden. die fch-prophylaxe ist aber überlegen und sollte bevorzugt werden (cruciani et al. ; engels, lau und barza ; gafter-gvili et al. ; neumann et al. ) . bei patienten, die analog eines studienprotokolls behandelt werden, empfiehlt sich die anlehnung an das protokoll, wobei kritische rückmeldungen von klinischen infektiologen an die jeweilige studienleitungen sicher erwünscht sind. die antibakterielle prophylaxe wird entweder nach granulozytärer regeneration oder mit beginn einer antibiotikatherapie, z. b. bei fieber unbekannter ursache, beendet (krüger et al. ; link et al. ). die kombination der fch-prophylaxe mit präparaten die eine bessere wirksamkeit gegen grampositive infektionserreger aufweisen, wird nicht empfohlen (freifeld et al. ; neumann et al. ) . zwei sonderfälle der antibakteriellen prophylaxe betreffen patienten nach allogener stammzelltransplantation: • die prophylaktische gabe von metronidazol bis zum tag + nach transplantation wird in einigen zentren zur prophylaxe einer graft-versus-host-erkrankung durchgeführt (beelen et al. ). • patienten mit chronischer gvhd und zusätzlicher immunsuppression sind auch besonders anfällig für infektionen mit grampositiven, bekapselten bakterien (atkinson et al. ; ochs et al. ) . daher kann nach individualmedizinischer abwägung auch hier eine antibiotikaprophylaxe (z. b. mit penicillin) indiziert sein (krüger et al. ) . randomisierte studien liegen für diese indikation jedoch nicht vor. ein weiterer ansatz zur reduktion von infektionen im verlauf der chemotherapie-induzierten granulozytopenie ist die verkürzung der granulozytopenie-dauer den einsatz hämatopoetischer wachstumsfaktoren. die aktuelle empfehlung der expertengruppe der agiho (vehrenschild et al. ) sieht den einsatz von g-csf bereits oberhalb eines fieberrisikos (während der granulozytopenie) von % vor, wobei ein so breiter einsatz von g-csf sicher nicht von allen onkologen befürwortet wird. aussagekräftige studien, die eine fch prophylaxe mit der gabe von g-csf vergleichen, liegen nicht vor. vor mehr als jahren haben stoutenbeek et al. ( ) die sdd als eine methode zur prävention nosokomialer infektionen in die intensivmedizin eingeführt. nosokomiale (beatmungsassoziierte) pneumonien (vap) sind in bestimmten hochrisikogruppen häufige und potenziell lebensbe-drohliche komplikationen und können zur quelle einer sekundären bakteriämie/sepsis werden (› kap. . das prinzip der klassischen sdd ist die applikation von nichtresorbierbaren antibiotika und antimykotika in den oberen gastrointestinaltrakt. dadurch wird eine lokale, selektive wirkung gegen potenziell pathogene mikroorganismen ohne beeinflussung der anaeroben darmflora erreicht. die these, die dem verfahren zugrunde liegt, ist, dass durch die sdd die kolonisationsresistenz gestärkt wird. der begriff der kolonisationsresistenz geht auf van der waaij zurück und meint, dass verschiedene faktoren von seiten des wirts und der darmflora die kolonisation durch potenziell pathogene mikroorganismen verhindern. demnach könnten durch den einsatz selektiv wirksamer antibiotika die physiologische flora geschont und gleichzeitig potenziell pathogene mikroorganismen eliminiert werden. dieses vorgehen führt nach van der waaij ( ) zur geringeren ausbreitung (multi) resistenter, potenziell pathogener mikroorganismen und zur infektionsprophylaxe bei patienten mit beeinträchtigter immun abwehr (van der waaij, berghuis-de vries und lekkerkerk ). nach einer vielzahl tierexperimenteller untersuchungen fand die sdd zunächst bei onkologischen patienten mit granulozytopenie anwendung. entscheidende klinische verbreitung erlangte das verfahren seit mitte der er-jahre bei beatmeten intensivpatienten. zum thema sdd bzw. selektive orale dekontamination (sod) existieren nunmehr mehr als randomisierte klinische studien und mehr als metaanalysen. um die primär endogenen infektionen in der prophylaxe mit zu erfassen, beinhaltet die sdd neben der topischen gabe von tobramycin, colistin und amphotericin b auch die i. v. applikation von cefotaxim über die ersten behandlungstage. medikamente und indikationen für eine antibiotikaprophylaxe bei neutropenie (krüger et al . (marshall et al. ). in der annahme, dass beim intensivpatienten durch reduzierte enterale ernährung, subileus und eine vielzahl anderer faktoren die translokation von endotoxin und bakterien aus den gastrointestinaltrakt gesteigert ist, messen viele autoren der enteralen komponente der sdd besondere bedeutung bei. zusätzlich werden die substanzen bei der klassischen sdd den beatmeten patienten als paste oral in die wangentaschen appliziert. dabei soll im falle einer stillen aspiration erregerhaltigen materials an der blockung des tubus vorbei die erregerlast als wesentlicher faktor der entstehung der beatmungsassoziierten pneumonie (vap, › kap. . ) reduziert werden. in der klinischen routine der intensivmedizin gibt es eine vielzahl von varianten der sdd, wobei die alleinige selektive orale dekontamination (sod) die am häufigsten untersuchte ist (dombrowski et al. ) . ihr ziel ist die reduktion der häufigkeit der vap und die reduktion der erregertransmission von patient zu patient aus dem oropharynx. die sdd ist wahrscheinlich die am besten untersuchte medikamentöse strategie zur infektionsprophylaxe. obwohl in einer vielzahl von studien die wirksamkeit von sod und sdd bei verschiedenen beatmeten patientengruppen nachgewiesen wurde, wird das verfahren bisher kaum in entsprechenden leitlinien empfohlen. grund ist nach ansicht der autoren der leitlinien neben der weiterhin unsicheren studienlage für einzelne erkrankungen, z. b. der sepsis, die potenzielle gefahr der selektion von mre (dellinger et al. ; guideline ; krinko ) . ebenso argumentieren die praktisch tätigen intensivmediziner. bei einer umfrage auf englischen intensivstationen gaben % der befragten an, wegen der unzureichenden evidenz und der gefahr der resistenzentwicklung auf die sdd zu verzichten (bastin und ryanna ) . inzwischen konnte in prospektiven rct gezeigt werden, dass durch sdd die sterblichkeit beatmeter intensivpatienten reduziert wird. bei chirurgischen und traumapatienten zeigten sich in der sdd-gruppe weniger infektionen, weniger organversagen und bei patienten mit apache-ii-score von - bei aufnahme auf die intensivstation eine niedrigere sterblichkeit. surveillancekulturen erbrachten keinen hinweis auf höhere resistenzraten in der sdd-gruppe, was in Übereinstimmung zu langzeitbeobachtungen mit sdd bei beatmeten patienten steht (dannemann et al. ; leone et al. , de jonge , heininger et al. ). abweichend von den meisten sdd-studien erfolgten die systemische antibiotikaprophylaxe über d mit ciprofloxacin und die topische therapie mit gentamicin und polymyxin ohne ein antimykotikum (krueger et al. ) . in einer weiteren studie bei chirurgischen und internistischen intensivpatienten zeigte sich eine signifikant geringere intensiv-und krankenhaussterblichkeit unter sdd. die randomisierung erfolgte stationsbezogen, um effekte durch geringere erregertransmissionsraten zwischen den sdd-und kontrollpatienten zu minimieren (de jonge et al. ) . ein ähnliches, allerdings multizentrisches studiendesign an über patienten untersuchte zusätzlich die wirksamkeit alleiniger sod ohne systemische antibiotikaprophylaxe. weder die sdd noch die sod zeigten in der studie einen Überlebensvorteil. in dieser studie hatten jedoch beide behandlungsgruppen ein primär höheres sterberisiko (höheres alter, höherer apache-ii-score). die logistische regressionsanalyse erbrachte einen signifikanten Überlebensvorteil für die patienten der sdd-gruppe (de smet et al. ). eine metaanalyse mit einschluss von > intensivpatienten zeigte, dass mit sdd die rate gramnegativer bakteriämien und die sterblichkeit reduziert werden können. am deutlichsten ist der effekt bei der klassischen sdd. die autoren kommen auf eine number needed to treat (nnt) von für einen geretteten patienten (silvestri et al. ). in einer weiteren metaanalyse zum nutzen des kompletten regimes der sdd, das neben der antibiotikaprophylaxe ein effektives hygieneregime und surveillancekulturen von rachen und stuhl beinhaltete, ergaben sich bei der analyse von rcts eine signifikante reduktion der mortalität und eine nnt von (silvestri et al. historie bereits in der bibel wird die absonderung von kranken mit isolierung für d bei weißen hautflecken erwähnt (leviticus : ). später wurde in anlehnung an die christliche fastenzeit von d (= quarantina di giorni), eine absonderung über diesen "reinigenden" zeitraum ("quarantenne") durchgeführt. so war eine der schutzmaßnahmen der republik venedig das festhalten von eintreffenden schiffen für d an der isola lazaretto nuovo (isolation), um sicher zu stellen, dass keine krankheiten in den lagunenstaat eingeschleppt werden. das erfolgte jedoch alles ohne kenntnis der hygienischen grundlagen von infektionserkrankungen. die pest im mittelalter ist ein beispiel für eine erfolgreiche empirische isolierung ohne wissenschaftliche grundlage. selbst in der gegenwart unterscheiden sich die reaktionen der bevölkerung und auch der krankenhausmitarbeiter kaum von denen früherer generationen. nach dem ersten ausbruch der sog. schweinegrippe flohen tausende von mexikanern in die usa. hiv-infizierte mitmenschen wurden in den anfängen der aids-pandemie sozial isoliert. die bemühungen anfang des . jahrhunderts, die ausbreitung der tbc zu reduzieren, sind ein weiteres beispiel empirischer infektionsmedizin: die meisten sanatorien liegen in den bergen mit einer starken, für mykobakterien letalen uv-strahlung. viele erkenntnisse gingen mangels dokumentation verloren und mussten z. b. im rahmen der tuberkulose-epidemien in den usa teilweise neu erarbeitet werden. sind aus den usa die ersten medizinischen dokumente zur isolierung von patienten erschienen (garner ) . krankenhäusern wurde empfohlen, patienten mit infektionskrankheiten in getrennten gebäuden (sog. pavillonbauweise) zu hospitalisieren. noch heute finden sich beispiele der pavillonbauweise aus jener zeit, z. b. ein teil der charité in berlin oder viele in der gründerzeit ( - ) erbaute krankenhäuser in wien. wissenschaftliche grundlagen der isolierung sind ein junges primär aus der pflege hervorgegangenes gebiet. dabei wurde viel an fachwissen eingebracht, das nicht aus randomisierten studien, sondern aus analysen der täglichen praxis resultierte. das erste auf erkenntnisbasis von bakteriellen erkrankungen konzipierte isolierungsmodell wurde publiziert. danach mussten sich mitarbeiter die hände nach patientenkontakt desinfizierend waschen sowie gegenstände und apparate desinfizieren, bevor sie aus dem bereich des infizierten patienten entfernt wurden. hierfür wurde erstmals der begriff "barrier nursing" verwendet. mit der einführung der sulfonamide und antibiotika wurden bakterielle infektionskrankheiten erstmals kausal behandelbar. diese entwicklung führte in den er-jahren des . jahrhunderts in den usa und vielen europäischen ländern zur schließung von isolierabteilungen. nach wurden im gegensatz zu europa, wo zumindest isolierzimmer auf stationen wieder berücksichtigt wurden, die meisten infektionskrankheiten in üblichen krankenzimmern behandelt. erschien als reaktion vor allem auf die zunahme der ni das erste detaillierte manual der cdc "isolation techniques for use in hospitals to assist general hospitals with isolation precautions". es wurde und überarbeitet und erschien zuletzt als "guideline for isolation precautions: preventing transmission of infectious agents in healthcare settings" der cdc (siegel et al. ). die regelmäßige Überarbeitung belegt die zentrale bedeutung dieser empfehlungen für die infektionsprävention. durch die definition der "standard precautions" (basishygiene) und die einführung der transmissionsbasierten isolierungstypen "airborne precautions" (Übertragung über die luft; inzwischen als "airborne infection isolation precautions" bezeichnet), "droplet precautions" (Übertragung durch tröpfchen) und "contact precautions" (Übertragung durch direkten kontakt) wurde ein klares handlungskonzept von großer praktischer bedeutung eingeführt. die protektive isolierung (umkehrisolierung) ist in die allgemeinen maßnahmen implementiert worden. darauf aufbauend erschienen empfehlun-gen und stellungnahmen zu isolierungsmaßnahmen bei speziellen erregern wie z. b. ebola und enterovirus-d (muscarella die Übertragung kann (dominierend) durch direkten oder indirekten kontakt, ferner durch tröpfchen (reichweite der > µm tröpfchen bis ≈ m), aerogen (reichweite der nuklei < µm bis ≈ m, verbleib in der raumluft mehrere stunden), parenteral oder über vektoren (sehr selten nosokomial) erfolgen. die direkte kontaktübertragung erfolgt von mensch zu mensch, die indirekte über die hände nach berühren kontaminierter gegenstände bzw. flächen bei unterlassener oder fehlerhafter händedesinfektion. zur tröpfchenübertragung kann es bei aerosol erzeugenden maßnahmen kommen. zu den über tröpfchen übertragbaren erregern gehören influenza-, adeno-, rhino-und sars-assoziierte coronaviren, b. pertussis, m. pneumoniae, n. meningitidis, legionella spp. und gruppe a-streptokokken. nasale s. aureus-träger können bei vorliegen einer virusinfektion des oberen respirationstrakts diesen erreger über m streuen (sheretz et al. ) . die vorstellung, dass durch verdunstung des flüssigkeitsanteils die im tröpfchen enthaltenen erreger als sehr kleine tröpfchenkerne (droplet nuclei) lange in der schwebephase bleiben und damit das risiko einer ansteckung erhöhen, wird für die lungentuberkulose angenommen, lässt sich aber nicht unbedingt auf andere erreger übertragen (cole und cook ) . aerogene Übertragung: nur bei wenigen erregern ist der nachweis gelungen, dass sie als partikel über die luft übertragen werden. beispiel ist das varicella-zoster-virus, bei dem ansteckungen bis zur distanz von m beschrieben sind und das noch in m entfernung von der infektionsquelle nachweisbar war (sawyer et al. ). aerogene Übertragung findet auch bei masern (bloch et al. ) , m. tuberculosis und schimmelpilzsporen (aspergillus spp.) statt (brenier-pinchart et al. ; haley et al. ). die ausbreitung von viren über den luftweg wurde u. a. für influenza-, noro- und rotaviren beschrieben (chadwick und mccann ) , allerdings nur im bereich des patientenzimmers. bei neu auftretenden krankheitserregern müssen, sofern die eigenschaften nicht genau bekannt sind, je nach der gefährlichkeit u. u. maximale präventionsmaßnahmen ergriffen werden. ein beispiel sind humane bocaviren, die atemwegsinfektionen auslösen, und sich in bezug auf ihre tenazität wahrscheinlich ähnlich wie das humane parvovirus b verhalten (schildgen et al. grundsätzlich können bei der isolierung vorliegende besonderheiten des patienten nicht berücksichtigt werden, weil das eine hohe präsenz der krankenhaushygiene vor ort voraussetzt bzw. einen hohen andauernden aufwand für die praxisanleitung des personals erfordert. deshalb wurden transmissionsbasierte isolierungsmodelle eingeführt, die sich bei gleichzeitiger einhaltung der basishygiene als ausreichend effektiv erwiesen haben. da die meisten krankenhäuser über zu wenige einzelzimmer/isolierzimmer verfügen (haertel et al. ) , müssen verschiedene gesichtspunkte bei der unterbringung der patienten berücksichtigt werden. bei begründetem verdacht auf eine übertragbare erkrankung, bei der vermutlich die maßnahmen der basishygiene nicht ausreichen, sollen entsprechend der verdachtsdiagnose auf der basis einer risikoanalyse spezifische schutzmaßnahmen eingeleitet werden. (bruns et al . ; diedrich ; kiehl , siegel et al . bei einer nosokomialen häufung (ausbruch) sollte auch die laufende desinfektion so durchgeführt werden, dass der jeweilige erreger wie bei der schlussdesinfektion erfasst wird. dies kann ggf. mit einer deutlichen raumluftbelastung verbunden sein, daher ist während und kurz nach der ausführung dieser arbeiten auf eine gründliche lüftung der patientenzimmer zu achten. alle potenziell kontaminierten materialien, die aus dem patientenzimmer entfernt werden müssen, müssen so transportiert werden, dass eine freisetzung des jeweiligen erregers außerhalb des patientenzimmers sicher unterbunden wird. bettpfannen oder urinflaschen müssen unmittelbar und direkt in das steckbecken-spülgerät gegeben werden und dürfen keinesfalls im unreinen arbeitsraum "zwischengelagert" werden. dies setzt voraus, dass steckbeckenspülgeräte in ausreichender zahl auf der jeweiligen station und möglichst in der nähe der isolierten patienten vorhanden sind. sabine wicker, axel kramer und frank-albert pitten zur prävention sowohl von ni als auch von arbeitsbedingten infektionen der mitarbeiter ist die enge zusammenarbeit von krankenhaushygiene und betriebsärzten unabdingbar. krankenhaushygiene und betriebsärzte sollten eine kooperierende einheit bilden, um erfolgreich zu sein. in der universitätsmedizin greifswald findet aus diesem grund der monatliche jour fixe des ärztlichen direktors gemeinsam mit der krankenhaushygiene, dem betriebsärztlichen dienst und der apotheke statt, um das gemeinsame vorgehen abzustimmen und zu koordinieren. am universitätsklinikum frankfurt gewährleistet die enge kooperation zwischen krankenhaushygiene und betriebsärztlichem dienst, dass schnell und effektiv auf infektionsgefährdungen reagiert werden kann und dass präventive maßnahmen sowohl für patienten als auch für das medizinische personal implementiert sind. schutzimpfungen gehören zu den wichtigsten präventiven maßnahmen in der medizin, da sie nicht nur individualschutz bewirken, sondern bei erreichen hoher impfquoten die eliminierung und sogar ausrottung (eradikation) einzelner krankheitserreger regional bzw. weltweit ermöglichen. der impfschutz reicht allerdings in der deutschen bevölkerung bei weitem nicht aus, um das auftreten bzw. die weiterverbreitung bestimmter infektionskrankheiten zu verhindern. für medizinisches personal ist die frage nach dem durchimpfungsgrad aufgrund der arbeitsbedingten infektionsgefährdung und der patientengefährdung durch ungeimpftes personal besonders brisant. leider ist die akzeptanz von schutzimpfungen im medizinischen bereich unzureichend. während die hepatitis b-impfung von den medizinischen beschäftigten meist sehr gut akzeptiert und auch aktiv nachgefragt wird, sind die impfquoten z. b. bzgl. influenza und pertussis alarmierend niedrig (› kap. . , › kap. . ) . hier liegt die wichtige aufgabe der betriebsärzte, die aufklärung bezüglich der impfpräventablen infektionen zu verbessern. in deutschland besteht keine impfpflicht. impfungen werden von den obersten gesundheitsbehörden der länder entsprechend § abs. ifsg "öffentlich empfohlen". darüber hinaus müssen al- le beschäftigten gemäß trba /bgr über notwendige immunisierungsmaßnahmen bei tätigkeitsaufnahme und aus gegebener veranlassung informiert werden. der gesundheitsschutz am arbeitsplatz wird primär durch die verordnung zur arbeitsmedizinischen vorsorge (arbmedvv) und ergänzend durch die biostoffverordnung (biostoffv) geregelt. impfungen sind bestandteil der arbeitsmedizinischen vorsorge und den beschäftigten anzubieten, soweit das risiko einer infektion tätigkeitsbedingt und im vergleich zur allgemeinbevölkerung erhöht ist und noch kein ausreichender immunschutz vorliegt; die kosten trägt der arbeitgeber. die nachfolgenden ausführungen orientieren sich an den empfehlungen der stiko ( ), die jährlich aktualisiert werden. zu den impfleistungen des arztes gehören neben der durchführung der impfung die erhebung der anamnese (frage nach kontraindikationen), die feststellung der aktuellen befindlichkeit zum ausschluss akuter erkrankungen, die umfassende aufklärung des impflings über die zu verhütende krankheit und ihre behandlungsmöglichkeiten, den nutzen der schutzimpfung für das individuum und die allgemeinheit, die art des impfstoffs, die durchführung der impfung, beginn und dauer des impfschutzes, verhalten nach der impfung, kontraindikationen, mögliche nebenwirkungen bzw. impfkomplikationen und termine für folge-und auffrischimpfungen (stiko ). die aufklärung sollte in den unterlagen des impfarztes dokumentiert werden. die kontraindikationen sind den fachinformationen der impfstoffhersteller zu entnehmen. nicht geimpft werden sollte personal mit akuten schweren erkrankungen (ausnahme postexpositionelle impfung). bei erlittenem impfschaden ist wegen der gesundheitlichen und wirtschaftlichen folgen ein antrag auf versorgung in der regel beim zuständigen versorgungsamt zu stellen. keine kontraindikationen sind z. b. banale infekte, auch mit subfebrilen temperaturen (≤ , °c), ein möglicher kontakt des impflings zu personen mit ansteckenden krankheiten, eine in der familie bekannte epilepsie und fieberkrämpfe in der anamnese des impflings, chronische erkrankungen, nicht progrediente erkrankungen des zns, ekzeme und andere dermatosen, lokalisierte hautinfektionen, behandlung mit antibiotika oder niedrigen kortikosteroiddosen, angeborene oder erworbene immundefekte bei impfung mit totimpfstoffen, schwangerschaft der mutter des impflings (varizellenimpfung nach risikoabwägung, es gilt jedoch zu bedenken, dass das risiko für ein konnatales varizellensyndrom bei einer seronegativen schwangeren mit kontakt zu ihrem ungeimpften und damit ansteckungsgefährdeten kind höher ist als das risiko einer solchen komplikation durch die impfung und ggf. die Übertragung von impfvarizellen durch ihr kind, stiko ), neugeborenenikterus und frühgeburtlichkeit (stiko ). bei applikation von lebendimpfstoffen sollte bei immundefekten die konsultation des behandelnden arztes eingeholt werden und bei evtl. gegebener indikation eine serologische kontrolle des impferfolgs erfolgen. allergien gegen impfstoffbestandteile (z. b. neomycin, streptomycin, hühnerproteine) sind potenzielle kontraindikationen. in der schwangerschaft sollten möglichst nur dringend indizierte impfungen vorgenommen werden. impfungen mit einem lebendimpfstoff, wie z. b. gegen masern-mumps-röteln (mmr) oder varizellen, sind in der schwangerschaft grundsätzlich kontraindiziert, wobei eine versehentlich in der schwangerschaft durchgeführte impfung mit lebendimpfstoffen jedoch keine indikation für einen schwangerschaftsabbruch darstellt. alle schwangere ab dem . trimenon und bei erhöhter gesundheitlicher gefährdung ab dem . trimenon sollten sich gegen influenza impfen lassen (stiko ). schwangere sind die hauptzielgruppe der who für die influenzaimpfung, da die impfung sowohl die mutter als auch später das neugeborene schützt. in mehreren ländern wird mittlerweile auch empfohlen, schwangere gegen pertussis zu impfen. als optimaler zeitpunkt wird die .- . schwangerschaftswoche angegeben. der plazentare transfer maternaler antikörper kann einen passiven schutz der neugeborenen und säuglinge gegen pertussis für ca. - monate bewirken. das amerikanische advisory committee on immunization practices (acip) der cdc empfiehlt seit , dass frauen in jeder schwangerschaft unabhängig vom impfstatus eine pertussisimpfung mit tdap erhalten sollen, um die neugeborenen vor schwerwiegenden verläufen einer pertussisinfektion zu schützen. zu den mindestabständen zwischen zwei lebendimpfungen sowie zur möglichkeit der koadministration von impfstoffen sind die fachinformationen des jeweiligen impfstoffs zu beachten. für einen lang dauernden impfschutz ist es von besonderer bedeutung, dass bei der grundimmunisierung der empfohlene mindestabstand zwischen vorletzter und letzter impfung nicht unterschritten wird (stiko ). • bei gabe von lebendimpfstoffen ist zu beachten, dass diese simultan oder in der regel in einem mindestabstand von wochen zu verabreichen sind -unter der voraussetzung, dass die impfreaktion vollständig abgeklungen ist und keine komplikationen aufgetreten sind. • bei schutzimpfungen mit totimpfstoffen müssen keine abstände, auch nicht zu lebendimpfstoffen, beachtet werden. • nach gabe von immunglobulinen sollten in einem zeitraum von monaten keine parenteral zu verabreichenden lebendimpfstoffe gegeben werden (stiko ). medizinisches personal sollte bereits vor dem ersten patientenkontakt über eine ausreichende immunität gegen impfpräventable arbeitsmedizinisch und/oder hygienisch indizierte impfungen verfügen. zum aufbau eines sicheren impfschutzes sollen die schutzimpfungen nach dem von der stiko empfohlenen impfkalender durchgeführt werden. bei nichteinhaltung empfohlener impfabstände muss mit dem impfschema nicht neu begonnen werden, da jede impfung zählt. so reicht auch nach einer über jahre zurückliegenden grundimmunisierung gegen diphtherie und tetanus eine boosterimpfung aus (cave: pertussis nicht vergessen!). mindestabstände zwischen den impfungen sind jedoch entsprechend fachinformation einzuhalten. die impfung ist einschließlich chargen-nummer und handelsname des impfstoffs im impfausweis und in der dokumentation des impfenden arztes zu dokumentieren. bei nichtvorlage des impfausweises ist eine impfbescheinigung auszustellen. jede ernsthafte gesundheitliche schädigung im zeitlichen zusammenhang mit einer impfung ist, wenn es gleichzeitig keine andere plausible erklärung für die erkrankung gibt, meldepflichtig. in extrem seltenen fällen werden schwere unerwünschte wirkungen beobachtet, die sofort diagnostisch abzuklären sind und umgehend entweder über das gesundheitsamt oder direkt dem bfarm und/oder dem paul ehrlich institut (formular oder online) gemeldet werden müssen. wird der impfende oder behandelnde arzt vom patienten bzw. dessen angehörigen auf den möglichen zusammenhang hingewiesen, ist die im ifsg festgelegte meldepflicht für alle verdachtsfälle einer impfkomplikation einzuhalten. zugleich ist der geschädigte auf die möglichkeit einer antragstellung auf versorgung hinzuweisen. die im einzelfall gebotenen maßnahmen zur immunisierung sind im einvernehmen mit dem arzt, der die arbeitsmedizinische vorsorge durchführt, festzulegen. die immunisierung ist kostenlos zu ermöglichen (› kap. . ). empfohlene schutzimpfungen: folgende impfungen werden für das gesamte medizinische personal einschließlich auszubildenden, praktikanten, studenten, reinigungspersonal, hebammen, externen dienstleistern mit patientenkontakt (z. b. fußpflege, physiotherapie) empfohlen, sofern kein impfschutz oder ein unklarer impfstatus vorliegt: tetanus, diphtherie, poliomyelitis, hepatitis a, hepatitis b, virusgrippe (influenza), pertussis, masern, mumps, röteln und varizellen. es wird allen beschäftigten im gesundheitsdienst dringend empfohlen, von der möglichkeit arbeitsmedizinisch und/oder hygienisch indizierter impfungen gebrauch zu machen. impfungen aufgrund eines erhöhten beruflichen risikos sind in den stiko-empfehlungen mit "b" gekennzeichnet. die impfungen gemäß stiko dienen sowohl dem schutz der beschäftigten als auch dem drittschutz (impfungen aus hygienischer indikation). bei medizinischem personal, das immuninkompetente patienten betreut, sollte der nachweis eines effektiven impfschutzes voraussetzung für die beschäftigung in einem risikobereich sein (wicker et al. ) für masern z. b. wird das infektionsrisiko von medizinischem personal -bis -mal so hoch geschätzt wie in der normalbevölkerung (wicker et al. ) . daher sollten alle medizinischen beschäftigten über eine sichere masernimmunität verfügen. varizellen: bei krankenhauspersonal mit unklarer varizellenanamnese muss serologisch der antikörperstatus abgeklärt werden. bei mangelndem schutz ist die impfung indiziert, das trifft insbesondere für seronegatives personal in den bereichen pädiatrie, onkologie, gynäkologie/geburtshilfe, intensivmedizin und betreuung immunsupprimierter patienten zu. pertussis: aufgrund der verlagerung der pertussis in das erwachsenenalter steigt die gefährdung für ungeimpfte, sodass wiederholt Übertragungen auf mitarbeiter im gesundheitswesen beobachtet wurden (kuncio et al. ; wicker und rose ; zivna et al. ). da bei der versorgung erkrankter kinder die exposition weitgehend unvermeidbar ist und das prä-und postexpositionelle management sehr ressourcenintensiv ist, ist die schutzimpfung die kostengünstigste und sicherste alternative (daskalaki et al. ) . pneumokokken: mitarbeiter ≥ jahren oder mit erhöhter gesundheitlicher gefährdung infolge einer grundkrankheit sollten gegen pneumokokken-infektionen immunisiert werden (stiko ). da die anzahl älterer mitarbeiter im gesundheitswesen und in der pflege in zukunft deutlich ansteigen wird, zeichnet sich erheblicher bedarf ab. die schutzimpfung gegen tbc auf der grundlage der bcg-impfung wird in deutschland nicht mehr empfohlen, da sie keinen sicheren schutz vor der infektion bietet. die schutzimpfung gegen die saisonale influenza wird für das gesamte personal jährlich dringend empfohlen. hierbei ist der jeweils aktuelle impfstoff, der die aktuellen sai- sonalen varianten umfasst, anzuwenden. die jährliche impfung wird auch dann empfohlen, wenn die antigenzusammensetzung des impfstoffs gegenüber der vorhergehenden saison unverändert ist. bei etwa % der geimpften im alter von - jahren wird eine schutzwirkung erreicht (cox, brokstad und ogra ; osterholm et al. ) . die impfquoten gegen influenza sind in den meisten einrichtungen des gesundheitswesens deutlich zu niedrig. in hessen gaben über % der befragten krankenhäuser influenzaimpfquoten beim medizinischen personal < % an, wobei lediglich rund % der befragten krankenhäuser die impfquote erfasst haben (wicker et al. ). dabei kommt einer immunisierung des medizinischen personals gerade zum patientenschutz eine besondere bedeutung zu, da gesichert ist, dass influenza-viren bereits in der inkubationszeit übertragen werden können. gewöhnlich wird seitens der betriebsärzte der krankenhäuser jeweils im herbst dem medizinischen personal die influenza-schutzimpfung angeboten. die erfahrung zeigt jedoch, dass das bloße angebot keinesfalls ausreicht, da die influenzaimpfung nur verhältnismäßig selten in anspruch genommen wird. besonders hohe impfquoten können nach eigener erfahrung erzielt werden, wenn der betriebsarzt auf die mitarbeiter zugeht, d. h. die impfung auf den stationen bzw. in den einzelnen pflegeeinheiten und funktionsbereichen (z. b. op, zna) anbietet. wenn auch die effektivität und effizienz der influenzaimpfung nicht optimal und ebenso abhängig vom impfstamm ist und selbst gegenüber dem tatsächlich zirkulierenden stamm u. u. keinen vollständigen schutz gewährleistet, war z. b. die anzahl der an a/h n erkrankten bei geimpftem gesundheitspersonal signifikant geringer (chu et al. ). personen mit anatomischer oder funktioneller asplenie sollte die impfung gegen h. influenzae typ b, pneumokokken und meningokokken empfohlen werden. meningokokken: bei ausbrüchen oder regionalen häufungen durch n. meningitidis kann von den gesundheitsbehörden in ergänzung zur antibiotikaprophylaxe eine impfempfehlung gegeben werden. bezüglich der anwendungshinweise der schutzimpfungen wird auf die stiko-empfehlungen verwiesen. hinweise zur postexpositionellen impfung bzw. anderen maßnahmen der speziellen prophylaxe übertragbarer krankheiten finden sich in den jeweils aktuellen stiko-empfehlungen. als präventionsmaßnahme werden hier die postexpositionelle impfung, die passive immunisierung durch die gabe von immunglobulinen sowie die chemoprophylaxe aufgeführt (stiko ). die jeweiligen indikationen und die anwendungshinweise sind tabellarisch zusammengefasst, um einen schnellen Überblick zu gewährleisten (aktuell tab. der stiko empfehlungen ). empfehlungen zur postexpositionellen prophylaxe (pep) einer hiv-infektion werden von der deutschen aids-gesellschaft in zusammenarbeit mit der Österreichischen aids-gesellschaft herausgegeben und regelmäßig aktualisiert (daig ). grundsätzlich sind folgende schutzmaßnahmen einzuhalten (details werden in den speziellen kapiteln erläutert): • anwendung medizinischer schutzhandschuhe und auswahl walter a. maier, weitergeführt durch michael k. faulde bei gesundheitsschädlingen im engeren sinn handelt es sich um gliederoder nagetiere, die krankheitserreger entweder als blutsaugende ektoparasiten direkt übertragen (aktive vektoren) oder als mechanische erregerverschlepper (passive vektoren bzw. hygieneschädlinge) im menschlichen umfeld verbreiten können. bei der aktiven erregerübertragung werden krankheitserreger definitionsgemäß beim hämophagen stech-(z. b. zecken) oder bissakt (z. b. milbenlarven mit paarigen mundwerkzeugen, nagetiere) in den wirtskörper eingebracht (faulde und freisel ; faulde und hoffmann ) . während bei den nagern bisse in aller regel akzidentell auftreten, fallen bei den arthropoden potenziell alle blutsaugenden arten in diese gruppe (faulde ; faulde und freisel ; faulde und hoffmann ; hoffmann die zahl der kopflausträger hat mit - % der gesamtbevölkerung relativ hohe werte erreicht, da sich p. capitis auch bei sehr gepflegten personen halten kann (burgess hygienemaßnahmen: gem. § abs. ifsg dürfen personen, bei denen ein kopflaus-befall festgestellt wurde, in den in § ifsg genannten gemeinschaftseinrichtungen keine lehr-, erziehungs-, pflege-, aufsichts-oder sonstige tätigkeit ausüben, bei denen sie kontakt zu den dort betreuten haben, bis nach der entscheidung des behandelnden arztes eine weiterverbreitung der verlausung durch sie nicht mehr zu befürchten ist. dieses verbot gilt entsprechend für die in der einrichtung betreuten kinder und jugendlichen mit der maßgabe, dass sie die dem betrieb der gemeinschaftseinrichtung dienenden räume nicht betreten, einrichtungen der gemeinschaftseinrichtung nicht benutzen und an veranstaltungen der gemeinschaftseinrichtung nicht teilnehmen dürfen. gem. § abs. ifsg haben die genannten beschäftigten und die betreuten bzw. deren sorgeberechtigte über eine verlausung der gemeinschaftseinrichtung unverzüglich mitteilung zu machen. nach abs. benachrichtigt darüber die leitung der einrichtung das zuständige gesundheitsamt. gemäß § ( ) können die landesregierungen zur verhütung und bekämpfung übertragbarer krankheiten rechtsverordnungen über die feststellung und die bekämpfung von gesundheitsschädlingen, kopfläusen und krätzmilben erlassen. sie können die ermächtigung durch rechtsverordnung auch auf andere stellen übertragen. § ifsg bestimmt außerdem, dass neben den in § ifsg genannten einrichtungen auch häuser der stationären pflege und betreuung, wohnheime und massenunterkünfte der infektionshygienischen Überwachung durch die gesundheitsämter unterliegen. treten z. b. in krankenhäusern, obdachlosenunterkünften oder gemeinschaftsunterkünften für asylbewerber, flüchtlinge und spätaussiedler läuse auf, gelten die obigen ausführungen in gleicher weise. behandlung: kopfläusekönnen nicht ohne gezielte behandlung des patienten beseitigt werden. hierzu werden primär insektizide eingesetzt, die aus der roten liste (antiparasitika) sowie der § ifsg-mittelliste zu entnehmen sind. ob als langfristige alternative eine systemische oder topische applikation des antihelminthikums ivermectin zur läusebehandlung eingesetzt werden sollte, ist offen (burgess ; habedank ; ko und elston ) . die topische behandlung sollte grundsätzlich nach d wiederholt werden, da die nissen nicht immer zuverlässig abgetötet werden (habedank ; maier ) . als wichtigster potenzieller vektor ist sie in mitteleuropa nur bei verwahrlosten personen oder personen ohne festen wohnsitz zu finden. im letzten jahrzehnt trat in den industrienationen besonders innerhalb der obdachlosenbevölkerung vor allem das wolhyni-oder -tage-fieber wieder vermehrt auf (burgess ; habedank ) . die kleiderlaus entwickelt sich weitgehend wie die kopflaus, ist aber etwas größer ( , - , mm) und robuster. sie hält sich im bereich der körperhaare zwischen körperoberfläche und unterwäsche auf, legt aber ihre nissen nicht an körperhaare, sondern an stofffasern (meist an nähten) ab. da die larven erst - wochen später schlüpfen, verhindert regelmäßiger wechsel der unterwäsche, wenigstens einmal wöchentlich, kleiderlausbefall sie ist mit , - mm die kleinste laus des menschen und hat eine gedrungene gestalt. filzläuse sind träger als kopf-und kleiderläuse und lassen ihre mundwerkzeuge oft stundenlang an derselben stelle eingestochen. daher wechseln sie weniger leicht den wirt. ihr auftreten kann dem arzt als hinweis auf möglicherweise vorhandene geschlechtskrankheiten dienen (burgess ; habedank ; ko und elston ) . besonders in alten-und pflegeheimen jedoch ist durch den engen beruflichen kontakt zwischen senioren und deren pflegepersonal eine Übertragung durch körperkontakt möglich. neben dem bevorzugten aufenthaltsort, den schamhaaren, findet man sie gelegentlich auch an den groben körperhaaren (bart-, augenbrauen-und achselhaare). bei befall bilden sich an der einstichstelle oft bläuliche hautveränderungen (maculae caeruleae), die diagnostische bedeutung haben können. die behandlung muss auf die empfindlichere haut der genitalregion rücksicht nehmen. insbesondere bei sexuell bedingter transmission müssen geschlechtspartner mitbehandelt werden. behandlung: schamläuse können nicht ohne gezielte behandlung des patienten beseitigt werden. hierzu werden primär insektizide eingesetzt, die aus der roten liste (antiparasitika) sowie der § ifsg-mittelliste zu entnehmen sind. ob als langfristige alternative eine systemische oder topische applikation des antihelminthikums ivermectin zur läusebehandlung eingesetzt werden sollte, ist offen (burgess ; habedank ; ko und elston die blinden, fußlosen, etwa mm großen flohlarven sind nicht blutsaugend und ernähren sich von hautschuppen sowie getrockneten blutresten am boden. die larven des menschenflohs (pulex irritans) finden sich außer in schweineställen auch in fußbodenritzen. in fugenlosen und sauberen böden können sie sich nicht halten. flohlarven verpuppen sich nach häutungen und einer entwicklungsdauer von etwa wochen. die puppenruhe beträgt zumindest - wochen und kann sich bis zu monaten ausdehnen. das schlüpfen erfolgt auf einen außenreiz hin, z. b. durch vibrationen, die einen potenziellen wirt ankündigen. daher ist eine hungerquarantäne in befallenen gebäuden oder zimmern nur über sehr lange sperrzeiten möglich! adulte flöhe stechen gern an körperstellen, an denen die kleidung eng anliegt. dort hinterlassen sie oft "perlschnurartige" stichfolgen (die sog. "flohstich-leiter") mit heftigem juckreiz. um das scheinbar unerklärliche, plötzliche auftreten einer flohplage erklären zu können, müssen die flöhe identifiziert werden. mit einem geeigneten bestimmungsschlüssel ist das mit einem einfachen mikroskop zumindest für die gebäudebefallenden floharten in mitteleuropa möglich (weidner aufgrund ihrer unvollständigen metamorphose saugen alle fünf larvenstadien und adulte tiere blut. ihre wirtsspezifität ist nicht streng auf den menschen begrenzt. die blutmahlzeit dauert etwa min, wonach sich die tiere wieder in ihrem schlupfwinkel verstecken. bettwanzen sind nachtaktiv und halten sich tagsüber in spalten, hinter tapeten, fußleisten, möbeln usw. auf. nach - d ist ihre entwicklung abgeschlossen. danach leben sie noch etwa jahr. bettwanzen weisen ein ausgeprägtes, wochen-bis monatelanges hungervermögen auf. durch die an den hüften der hinterbeine ausmündenden stinkdrüsen lässt sich ein bettwanzenbefall auch geruchlich feststellen. das wird beim bettwanzenmonitoring mit abgerichteten hunden genutzt, wobei die sensitivität und spezifität dieser methode noch ungeklärt ist (kuhn und van der pan ) . besonders in krankenhäusern und gesundheitseinrichtungen ist daher nie auf einen professionellen schädlingsbekämpfer zu verzichten. bei den aus tauben-und schwalbennestern vor allem in der kalten jahreszeit in bewohnte gebäude einwandernden wanzen handelt es sich in der regel um morphologisch sehr ähnliche vogelwanzen, die jedoch auch den menschen stechen können. vogelwanzen rufen keinen stationären gebäudebefall hervor, weshalb immer eine artdiagnostik erforderlich ist. die medizinische bedeutung von bettwanzen liegt vor allem in der teilweise heftigen stichreaktion, die von mensch zu mensch variieren kann, sowie in der teilweise starken psychischen belastung betroffener bei dauerbefall (harlan, faulde und baumann ) . extrem hohe befallsraten können in einzelfällen zu anämien führen. obwohl in bettwanzen bis heute etwa erreger nachgewiesen werden konnten, gibt es bislang noch keine konkreten hinweise auf eine aktive erregerübertragung über bettwanzenstiche auf den menschen (doggett et al. ; harlan, faulde und baumann ) . sie werden bis heute als reine hämophage hygieneschädlingenicht als aktive vektoren -angesehen (harlan, faulde und baumann ; kuhn, van der pan ) . argas reflexus lebt oft im dachstuhl von altbauten, die von tauben besiedelt werden oder wurden. sie saugen in allen entwicklungsstadien blut, ähnlich wie bettwanzen, und werden gelegentlich mit diesen verwechselt. in befallenen häusern können sie viele jahre ohne nahrung überleben und befallen menschen in den oberen stockwerken, vor allem wenn keine tauben mehr als blutquelle zur verfügung stehen. die taubenzeckenbekämpfung gestaltet sich sehr schwierig und muss fachpersonal vorbehalten bleiben. bei implementierung ausreichender baupräventiver maßnahmen haben taubenzecken in krankenhäusern keine bedeutung (faulde und freise ). der erreger der skabies oder krätze ist nur , - , mm groß. die milbe lebt im grunde bereits "endoparasitisch" im stratum corneum der haut. die weibchen graben bohrgänge, in denen sie vom zellsaft beschädigter zellen leben und ihre faeces absetzen. bevorzugt werden stellen, an denen die haut dünn und faltig ist, meist zwischen den fingern und am handgelenk, aber auch an ellenbogen, füßen, penis, skrotum, gesäß und achselhöhlen, bei frauen auch im bereich der mammae und mamillen (stary und stary ) . im bohrgang werden die eier abgelegt; die nach - d schlüpfenden larven häuten sich zweimal, bis nach - d die adulten milben entstehen. erst wenn die weibchen auf der haut befruchtet wurden, bohren sie sich in die haut desselben oder eines anderen wirts ein. der gesamtzyklus von ei zu ei dauert - d. ansteckung ist im regelfall nur durch intimen, persönlichen kontakt möglich, z. b. wenn gleichzeitig dasselbe bett benutzt wird. man nimmt an, dass für eine Übertragung eine mindestkontaktdauer von - min notwendig ist. eine Übertragung durch bettwäsche kann normalerweise ausgeschlossen werden, obwohl die milben - d, unter günstigen bedingungen sogar etwa eine woche, fern vom menschen überleben können. es gibt jedoch besonders heftige verlaufsformen der skabies, bei denen wegen der starken milbenvermehrung die ansteckungsgefahr bedeutend höher ist. in solchen fällen muss die wäsche entweder bei über °c gewaschen, d im plastikbeutel gelagert oder mit einem insektizid eingesprüht werden. auch das bügeln der wäsche tötet milben ab. klinik: das klinische bild der skabies ist bei wiederholter infektion ausgepräger als bei erstinfektion. die schwere hautreizung, die dabei entsteht, veranlasst zu heftigem und anhaltendem kratzen, vor allem nachts. sekundärinfektionen sind meist die folge. eine besonders schwere form ist die "norwegische krätze", die durch bildung einer dicken hornschicht über händen und füßen und papulären eruptionen an anderen körperstellen imponiert. obwohl die zahl der milben sehr hoch ist, verspürt der patient in diesem fall kaum juckreiz. epidemisches auftreten ist in asylantenheimen, altenheimen und krankenhäusern nicht selten. bei leukämischen kindern soll sie sich ebenfalls bevorzugt ausbreiten können (gröschel ) . die diagnose der skabies ist nur bei mikroskopischem nachweis der milben eindeutig gesichert. dazu sucht man das etwas breitere ende eines bohrgangs in der haut, in dem die weibchen zu vermuten sind, entfernt mit scharfer kanülenspitze die haut und überträgt die milben, die meist an der nadelspitze hängen bleiben, auf einen objektträger, evtl. mit einem tropfen immersionsöl (stary und stary ) . die behandlung der krätze muss topisch oder mit oralen antiparasitika durchgeführt werden. wegen der geringen toxizität werden heute zumeist akarizide pyrethroide, z. b. permethrin und allethrin, bevorzugt (reich ; stary und stary ) . bei aids-patienten hat sich ivermectin in einmaliger oraler dosis offenbar als medikament bewährt (stary und stary ; wolff hygieneschädlingen sind vor allem mechanische verschlepper von krankheitserregern oder um passive vektoren. sie sind nicht hämophag, in ihnen findet kein entwicklungszyklus eines pathogens und i. d. r. keine erregervermehrung statt. lia spp.) bekannt. die larven leben an verwesenden kadavern, exkrementen und in nekrotischem gewebe. daher treten sie vor allem in tropischen regionen sowie unter krisensituationen häufig auch als wundmyiasis-erreger auf; in mitteleuropa gelegentlich während der sommermonate (hogsette und amendt ). besonders angelockt werden diese fliegen durch übelriechende, eitrige geschwüre. maden von speziellen l.-sericata-stämmen werden zur behandlung chronischer wunden eingesetzt, da sie diese debridieren (durch alimentäre aufnahme und lytische zersetzung), antiseptisch effektiv sind und die wundheilung durch freigesetzte faktoren fördern (daeschlein et al. b ). sie schmeißen (werfen!) ihre larven im flug auf fleisch und wunden, legen also keine eier ab. im Übrigen verhalten sie sich wie aasfliegen. in diese nicht blutsaugende unterfamilie der kleinen ( - mm) schmetterlingsmücken (psychodinae) gehören auch die abortmücken der gattung psychoda. sie entwickeln sich vor allem in offenen fäkalien und waren zu zeiten vom wohnhausfernen toilettenanlagen deutlich verbreiteter und als verschlepper von krankheitserregern wichtiger, als heute. nach einschleppung aus dem mittelmeerraum und geografischer ausbreitung von clogmia albipunctata in deutschland änderte sich diese situation. diese vormals in den tropen und subtropen heimische schmetterlingsmücke hat sich derzeit östlich bis berlin und nördlich bis etwa kiel ausgebreitet, entwickelte einen ausgeprägten synanthropismus und ist vor allem in öffentlichen gebäuden und auch in krankenhäusern mittlerweile häufig und ganzjährig anzutreffen (faulde und spiesberge ). aus deutschen krankenhäusern wurden an ihr bakterienspezies aus gattungen isoliert. neben a. baumannii, s. maltophilia, k. pneumoniae ssp. pneumoniae wurden noch eine reihe weiterer nosokomialer pathogene identifiziert (faulde und spiesberger ) . der erstmalige nachweis von a. baumannii auf einer insektenoberfläche eröffnete völlig neue epidemiologische perspektiven sowie neue Übertragungsmöglichkeiten dieses immer wichtiger werdenden nosokomialen pathogens. außer multiresistenten ( mrgn), carbapenemase-produzierenden s. maltophilia konnten bislang keine weiteren besonderen resistenzmuster oder multiresistenzen festgestellt werden. das potenzial als mechanischer verschlepper von krankheitserregern in krankenhäusern wurde dennoch belegt (faulde und spiesberger ) . die larven von c. albipunctata entwickeln sich aquatisch inauch kleinsten -wasseransammlungen. in krankenhäusern wurden als brutplätze identifiziert: • toiletten und urinale, insbesondere wenn diese wenig genutzt werden, • duschen-und bodensiphons in duschkabinen, insbesondere, wenn diese unzureichend gereinigt und saniert wurden, (meistens lag eine verstopfung des siphons durch haarknäuel vor.) • in krankenhausküchen sowie in den sanitärräumen des küchenpersonals vorwiegend ungereinigte und verstopfte bodensiphons, • wasseransammlungen, die im zusammenhang mit dauerleckagen von wasserrohren, nicht abfließendem kondenswasser oder abläufen von ve-wasseranlagen stehen (faulde und spiesberger ) . die behebung dieser schwachstellen durch ausreichendes hygieneund wassermanagement reduziert oder eradiziert bereits einen befall. c . albipunctata tritt als sensibler indikator für unzureichendes hygieneund wassermanagement in krankenhäusern auf. schaben (blattodea) sind urtümliche insekten, die sich -dorsoventral abgeflacht -gut in ritzen und spalten verstecken können. sie lieben wärme und hohe luftfeuchtigkeit. zentren des nicht seltenen befalls in krankenhäusern sind daher meist zentral-und stationsküchen, toiletten und bäder. bei der nahrungsaufnahme sind schaben nicht wählerisch. sie bevorzugen zwar weiche, zuckeroder stärkehaltige lebensmittel, verschmähen aber auch blut, sputum, exkremente u. Ä. stoffe nicht. schon die anwesenheit von schaben kann den gesundungsprozess eines patienten stören, wenn sie mit unberechenbaren bewegungen durch den raum huschen und ihren charakteristischen, unangenehmen geruch verbreiten. außerdem können sie allergien verursachen (pospischil ; rust ) . von hygienischer bedeutung ist ihr verhalten bei der nahrungssuche. sie laufen wahllos über offen zugängliche speisen; dabei erbrechen sie gelegentlich halbverdautes futter und setzen ihren kot auf speisen, geschirr, möbeln, instrumenten usw. ab. dadurch können die verschiedensten krankheitserreger auf lebensmittel und instrumente gelangen (pospischil ; rust ) . ob im konkreten fall eine kontamination zustande kommt, hängt davon ab, ob die schaben zuvor kontakt mit nosokomialen erregern aus dem krankenhausumfeld hatten. typischerweise waren in einem klinikum alle kliniken von schaben befallen, nicht aber die zugehörigen institute, sofern sie räumlich getrennt waren, weil über die lebensmittelversorgung der patienten auch die schaben versorgt wurden (maier ) . hygienemaßnahmen: schaben, die üblicherweise mit lebensmitteln eingeschleppt werden, können sich in einem sauberen gebäude ohne schlupfwinkel nicht einnisten. ein schlechter erhaltungszustand oder konstruktionsbedingte mängel eines gebäudes gewähren ein reichliches angebot an schlupfwinkeln. schaben verstecken sich tagsüber in spalten und ritzen und kommen erst bei dunkelheit zum vorschein. durch ausbessern von rissen, losen kacheln usw. wird das verhindert (pospischil ; rust ) . werden schmutziges verbandmaterial, sputum, fäkalien und abfälle ordnungsgemäß sofort beseitigt, nimmt das risiko einer verschleppung von krankheitserregern durch schaben ab. größtmögliche sauberkeit ist ein wesentlicher faktor, um die verbreitung von krankheitserregern zu verhindern und auch die einfachste bekämpfungsmaßnahme, weil die schabenvermehrung wegen des damit verbundenen nahrungsmangels begrenzt wird. neben der konsequenten beseitigung der abfälle nach jeder mahlzeit und ihrer aufbewahrung in gut schließenden behältern, möglichst außerhalb des krankenhauses, muss bedacht werden, dass lebensmittel grundsätzlich schabensicher aufbewahrt werden müssen. exkremente und schmutziges verbandmaterial müssen sofort restlos beseitigt werden. die einhaltung dieser regeln wird zu einer entwicklungshemmung, bei konsequenter durchführung zur beseitigung der schaben führen. als schabenarten sind in krankenhäusern mitteleuropas blattella germanica, blatta orientalis und supella longipalpa von bedeutung (pospischil ; rust ) . deutsche schabe (blattella germanica): sie ist im adultstadium - mm lang und hell-bis schmutzigbraun. alle stadien zeigen auf dem thorax zwei schwarze längsstreifen. die adulten können mithilfe besonderer haftlappen über senkrechte, glatte wände laufen. nach der kopulation bildet das weibchen eipakete (ootheken), in denen sich die larven entwickeln und die nach - wochen abgelegt werden; danach schlüpfen die larven. nach häutungen der männchen bzw. der weibchen wird im günstigsten fall nach etwa - d das imaginalstadium erreicht. die optimale temperatur dafür liegt bei °c. orientalische schabe (blatta orientalis): sie fällt durch ihre größe ( - mm) und fast schwarze oder schokoladenbraune färbung auf. nur das männchen trägt flügel. erst nach häutungen ist das weibchen nach durchschnittlich d, das männchen nach nur häutungen und d ausgereift. die oothek wird nach - d abgelegt, die larven schlüpfen aber erst nach d (bei °c, bei niedrigeren temperaturen viel später). das temperaturoptimum liegt zwischen und °c. da sie also auch relativ niedrige temperaturen toleriert, findet man b. orientalis auch in kellerräumen. braunbandschabe (supella longipalpa): sie wurde nach dem zweiten weltkrieg mit lebensmitteln aus den usa nach deutschland eingeschleppt. sie ähnelt der deutschen schabe, besitzt aber keine längsstreifen auf dem thorax: stattdessen ist der thorax ist sehr dunkel mit hellem seitenrand. auffallend ist ein braunes band zwischen zwei gelblichen querstreifen auf hinterbrust und abdomen. neben küchen und ähnlichen räumen, wie sie auch von der deutschen schabe besiedelt werden, verschont sie auch wohn-und schlafräume nicht. daher findet man sie u. a. auch in schubladen von schreibtischen und kommoden (möbelschabe), wo sie ihre ootheken verstecken. die pharaoameise (monomorium pharaonis) ist zum ständigen bewohner zentralbeheizter gebäude und vieler krankenhäuser ge-worden (oi ) . sie baut ihre staaten in nestern unter fußböden und in mauerritzen. dort legen die königinnen ihre eier ab, bis der staat auf mehrere tausend ameisen angewachsen ist. die nur , - , mm großen arbeiterinnen sammeln nahrung, die in das nest gebracht wird und zur ernährung der königinnen und larven dient. bevorzugt nehmen sie zucker oder honig, aber auch proteine (fleisch, käse) oder fett auf. mit spürsinn finden sie diese nahrung auch in verschlossenen behältern, da sie klein genug sind, um durch engste ritzen zu schlüpfen. hat eine arbeiterin den zugang gefunden, folgen über markierte straßen andere nach. im krankenhaus können pharaoameisen erhebliche probleme verursachen, wenn sie in sterile verbände, geräte, bakteriologische kulturen usw. einwandern und diese kontaminieren. aber auch patienten selbst, vor allem frischoperierte, bewegungsunfähige schwerkranke und neugeborene können befallen werden. die ameisen wandern unter wund-und gipsverbände und benagen die wunden. dabei können sie verschiedenste krankheitserreger wie streptokokken, staphylococcus spp. und clostridium spp. übertragen (oi ) . die bekämpfung ist schwierig, da die königinnen im nest nicht durch insektizide erreicht werden. als vorratsschädlinge kommen eine große zahl von insekten (motten, käfer) und milben in betracht. die hygienische bedeutung dieser arthopoden ist gering, da sie normalerweise keine krankheiten verursachen. anders ist es bei synanthropen schadnagern wie ratten und mäusen, die wegen ihrer eigenschaften als mechanischer Überträger von krankheitserregern, aber auch als erregerreservoir gleichzeitig eine funktion als gesundheitsschädling besitzen (faulde ) . mäuse, ratten: sie können in der vorratshaltung schädlich werden und krankheitserreger übertragen (faulde ) . durch vorbeugende bauliche maßnahmen und regelmäßige kontrollen, z. b. anbringen engmaschiger gitter vor kellerfenstern, muss dafür gesorgt werden, dass nager nicht in krankenhausgebäude eindringen können. nagerbefall ist in kellerräumen von krankenhäusern und gesundheitseinrichtungen nicht selten, spielt aber in hygienisch gut geführten krankenhäusern nur eine untergeordnete rolle und wird daher nicht weiter betrachtet. während die topische und orale behandlung von körperungeziefer am patienten mit arzneimitteln aus der gruppe der antiparasitika durchgeführt wird, gestalten sich schädlingsbekämpfungen unter freisetzung biozider substanzen und präparate in die umwelt völlig anders. die verfügbarkeitsbreite von insektiziden und akariziden für nicht sachkundige "laien" ist in den letzten jahren und jahrzehn- ten gesetzlich stark eingeschränkt worden (faulde ) . zum schutz des verbrauchers und seiner umwelt sind für den "hausgebrauch" derzeit noch fertig formulierte "laienmittel" kommerziell verfügbar. insektizide und akarizide konzentrate in anwendungsüblichen mengen und konfektionierungen sind derzeit z. b. für die anwendung an haustieren gegen zecken-und flohbefall sowie für die bekleidungs-und moskitonetzimprägnierung für die vektorenabwehr in tropischen regionen erhältlich (faulde ) . die ausbringung professionell einzusetzender insektizide, akarizide und rodentizide ist allein entsprechend ausgebildetem fachpersonal vorbehalten. aus diesem grund wird auf mittelauswahlkriterien und toxikologische eigenschaften von bioziden nicht eingegangen. diese können für den konkreten bedarf aus der einschlägigen literatur entnommen werden (faulde ; maroni et al. ). zum schutz des menschen vor übertragbaren krankheiten dürfen bei behördlich angeordneten entseuchungen (desinfektion), entwesungen (bekämpfung von gliedertieren) und maßnahmen zur bekämpfung von wirbeltieren, durch die krankheitserreger verbreitet werden können, nur mittel und verfahren verwendet werden, die von der zuständigen bundesoberbehörde in einer liste im bundesgesundheitsblatt bekannt gemacht worden sind. auf ausreichende wirksamkeit geprüfte und anerkannte mittel und verfahren zur bekämpfung von tierischen gesundheitsschädlingen nach § ifsg werden in jeweils aktualisierten fassungen im bundesgesundheitsblatt veröffentlicht (klasen et al. ) . dem anwender steht die wahl des mittels bei schädlingsbekämpfungsmaßnahmen grundsätzlich frei, soweit es sich nicht um behördlich angeordnete maßnahmen bei entseuchungen, entwesungen oder maßnahmen gegen wirbeltiere gemäß § ifsg handelt. da bei auftreten von gesundheitsschädlingen in krankenhäusern und anderen gesundheitseinrichtungen in der regel immer der begründete verdacht einer erregerübertragung oder zumindest -verschleppung vorliegt, ist die ausschließliche nutzung dieser behördlich und unabhängig auf ausreichende wirksamkeit geprüften mittel und verfahren dringend zu empfehlen (klasen et al. ). (indirekte Übertragung durch kontaminierte kleidung möglich), cryptococcus spp ifsg hat die zuständige behörde (gesundheitsamt) anzuordnen, dass personen, die an lungenpest oder an von mensch zu mensch übertragbarem hämorrhagischem fieber erkrankt oder dessen verdächtig sind, unverzüglich in einem krankenhaus oder einer für diese krankheiten geeigneten einrichtung abgesondert werden adverse effects of isolation in hospitalised patients efficacy and safety of oxum in treatment of chronic wounds a prospective randomized trial of povidone-iodine prophylactic cleansing of the rectum before transrectal ultrasound guided prostate biopsy versuche mit sporen von b . subtilis in defibriniertem blut zur prüfung der wirksamkeit von gas-sterilisatoren versuche zur kaltsterilisation mit formalindämpfen the value of chlorhexidine gluconate wipes and prepacked washcloths to prevent the spread of pathogens -a systematic review evaluation of microbiocidal activity of superoxidized water on hospital 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gynäkologie und geburtshilfe (dggh) anforderungskatalog für die aufnahme von chemischen desinfektionsverfahren in die desinfektionsmittel-liste der dghm . wiesbaden: mhp strategien zur sicherung rationaler antibiotika-anwendung im krankenhaus . awmf-registernr empfehlungen für die validierung und routineüberwachung von sterilisationsprozessen mit sattdampf für medizinprodukte leitlinie zur validierung der manuellen reinigung und manuellen chemischen desinfektion von medizinprodukten . wiesbaden: mhp-verlag reinigung in krankenhäusern -eine umfrage der dgkh im jahr stellungnahme der deutschen gesellschaft für pädiatrische infektiologie und des paed ic projektes zur erfassung des antibiotika-verbrauches in kinderkliniken im rahmen eines antibiotic stewardship programmes leitlinie für die validierung des siegelprozesses nach din en iso - . zentr steril suppl robert koch-institut . leitlinie zur prüfung von chemischen desinfektionsmitteln auf wirksamkeit gegen viren in der humanmedizin fassung vom . august deutsche vereinigung zur bekämpfung der viruskrankheiten (dvv) . quantitative prüfung der viruziden wirksamkeit chemischer desinfektionsmittel auf nicht-porösen oberflächen liste der nach den richtlinien der dvg geprüften und wirksam befundenen desinfektionsmittel für die tierhaltung liste der nach den richtlinien der dvg ( . auflage, ) geprüften und wirksam befundenen desinfektionsmittel für den lebensmittelbereich prophylactic chemotherapy with fosfomycin trometamol during transurethral surgery and urological manoeuvres verfügbar auf www .rki .de din -prüfverfahren zum nachweis der eignung eines medizinproduktsimulators bei der dampf-sterilisation -medizinproduktsimulatorprüfung din -sterilisation -dampf-sterilisatoren din teil -sterilisation -niedertemperatur-sterilisatoren -teil : bauliche anforderungen und anforderungen an die betriebsmittel sowie den betrieb von ethylenoxid-sterilisatoren din -sterilisation -sterilgutversorgung (teilweise ersetzt durch din en ) . din en -sterilisation -dampf-sterilisatoren -groß-sterilisatoren din en -sterilisatoren für medizinische zwecke, ethylenoxid-sterilisatoren din en -sterilisatoren für medizinische zwecke -niedertemperatur-dampf-formaldehyd-sterilisatoren -anforderungen und prüfung din en -sterilisation von medizinprodukten -niedertemperatur-dampf-formaldehyd din en . chemische desinfektion und antiseptika -quantitatives prüfverfahren zur bestimmung der bakteriziden und levuroziden wirkung auf nicht-porösen oberflächen mit mechanischer einwirkung mithilfe von tüchern oder mops im humanmedizinischen bereich ( -felder-test) -prüfverfahren und anforderungen din en teil -sterilisation von medizinprodukten -anforderungen an medizinprodukte, die als "steril" gekennzeichnet werden -teil : anforderungen an medizinprodukte, die in der endpackung sterilisiert wurden teil -sicherheitsbestimmungen für elektrische mess-, steuer teil - -sicherheitsbestimmungen für elektrische mess-, steuer-, regel-und laborgeräte -teil - : besondere anforderungen an sterilisatoren und reinigungs-desinfektionsgeräte für die behandlung medizinischen materials din en teil -nichtbiologische systeme für den gebrauch in sterilisatoren -teil : festlegungen von indikatorsystemen und prüfkörpern für die leistungsprüfung von klein-sterilisatoren vom typ b und vom typ s din en teil bis -verpackungen für in der endverpackung zu sterilisierende medizinprodukte din en iso . teil -biologische beurteilung von medizinprodukten -teil teil -sterilisation von produkten für die gesundheitsfürsorge -ethylenoxid -teil : anforderungen an die entwicklung teil bis -sterilisation von produkten für die gesundheitsfürsorge -biologische indikatoren teil , und -sterilisation von produkten für die gesundheitsfürsorge -chemische indikatoren medizinprodukte -qualitätsmanagementsysteme -anforderungen für regulatorische zwecke (iso : + cor -sterilisation von produkten für die gesundheitsfürsorge -biologische indikatoren -leitfaden für die auswahl, verwendung und interpretation von ergebnissen -sterilisation von produkten für die gesundheitsfürsorge -allgemeine anforderungen an die charakterisierung eines sterilisierenden agens und an die entwicklung medizinprodukte -anwendung des risikomanagements auf medizinprodukte (iso : , korrigierte fassung din en iso teile - . reinigungs-desinfektionsgeräte din en iso . -sterilisation von medizinprodukten -vom hersteller zu stellende informationen zur wiederaufbereitung von resterilisierbaren medizinprodukten din en iso . teil und -sterilisation von produkten für die gesundheitsfürsorge sterilisation von medizinprodukten -vom hersteller bereitzustellende informationen für die aufbereitung von resterilisierbaren medizinprodukten sterilisation von produkten für die gesundheitsfürsorge -feuchte hitze -teil : anforderungen an die entwicklung sterilisation von produkten für die gesundheitsfürsorge -trockene hitze -anforderungen an die entwicklung (normentwurf) -sterilisation von medizinprodukten -niedertemperatur-dampf-formaldehyd -anforderungen an die entwicklung beschichtungsstoffe -beurteilung von beschichtungsschäden -bewertung der menge und der größe von schäden und der intensität von gleichmäßigen veränderungen im aussehen -teil : allgemeine einführung und bewertungssystem classification of wounds at risk and their antimicrobial treatment with polihexanide: a practice-oriented expert recommendation safety and morbidity of first and repeat transrectal ultrasound guided prostate needle biopsies: results of a prospective european prostate cancer detection study removal of nosocomial pathogens from the contaminated glove bed bugs: clinical relevance and control options clinical components and associated behavioural aspects of a complex healthcare intervention: multi-methods study of selective decontamination of the digestive tract in critical care biofilms and device-associated infections the effects of ophthalmic preservatives on corneal epithelium of the rabbit: a scanning electron microscopical study an outbreak of norovirus infection in a bone marrow transplant unit triclosan exposure increases triclosan resistance and influences taxonomic composition of benthic bacterial communities determination of the efficancy of sterile barrier systems against microbial challanges during transport and storage estimated risk of endocarditis in adults with predisposing cardiac conditions undergoing dental procedures with or without antibiotic prophylaxis keimspektren und antibiotika bei odontogenen infektionen -renaissance der penicilline? weichteilinfektionen in der mund-, kiefer-und plastischen gesichtschirurgie -keimspektren und antibiotika reduction of clostridium difficile and vancomycin-resistant enterococcus contamination of environmental surfaces after an intervention to improve cleaning methods berufliche expositionen gegenüber formaldehyd im gesundheitswesen prospective, double-blinded, randomised controlled trial assessing the effect of an octenidine-based hydrogel on bacterial colonisation and epithelialization of skin graft wounds in burn patients chemical disinfectants and antiseptics . virucidal quantitative suspension test for chemical disinfectants and antiseptics used in human medicine . test method and requirements (phase , step ) . en efficacy of quinolone prophylaxis in neutropenic cancer patients: a meta-analysis morbidity of ultrasound-guided transrectal core biopsy of the prostate without prophylactic antibiotic therapy . a prospective study in cases poly(hexamethylenebiguanide) hydrochloride (phmb) -case , pc code: . toxicology disciplinary chapter for the reregistration eligibility decision document . environmental protection agency document guidelines for carcinogen risk assessment (final) reregistration eligibility decision (red) for phmb anthrax spore decontamination using hydrogen peroxide vapor interventions for replacing missing teeth: antibiotics at dental implant placement to prevent complications disinfection efficacy against parvovirus compared with reference viruses opinion of the scientific panel on food additives, flavourings, processing aids and materials in contact with food on a request from the commission related to propan- -ol as a carrier solvent for flavourings, question number efsa-q- - simulation and patient safety: evaluative checklists for central venous catheter insertion juni (abl . eg nr . l s . ) zuletzt geändert durch artikel der richtlinie influence of biofilms by chemical disinfectants and mechanical cleaning allergy to chlorhexidine: beware of the central venous catheter arthropoden und nagetiere als krankheitsverursacher sowie Überträger und reservoire von krankheitserregern vorkommen und verhütung vektorassoziierter erkrankungen des menschen in deutschland unter berücksichtigung zoonotischer hospital infestations by the moth fly, clogmia albipunctata (diptera: psychodinae), in germany role of the moth fly clogmia albipunctata (diptera: psychodinae) as a mechanical vector of bacterial pathogens in hospitals krank durch arthropoden ratten und mäuse -unterschätzte Überträger und reservoire gefährlicher infektionskrankheiten? chlorhexidine official fda information, side effects and uses the incidence of fluoroquinolone resistant infections after prostate biopsy -are fluoroquinolones still effective prophylaxis? clinical and microbiologic features guiding treatment recommendations for brain abscesses in children untersuchungen von sterilverpackungsmaterial für die formaldehyd-sterilisation untersuchungen zur sterilisation mit formaldehyddampf im unterdruckverfahren, mikrobiologische und toxikologische aspekte kondensation bei der dampfsterilisation poröser güter prevention of perioperative infection glycerol accelerates recovery of barrier function in vivo rahmenkonzept zur gefahrenabwehr bei außergewöhnlichen seuchengeschehen implementation of evidence-based practices for surgical site infection prophylaxis: results of a pre-and postintervention study the house fly (musca domestica) as a potential vector of metazoan parasites caught in a pig-pen in germany comprehensive study on the occurrence and distribution of pathogenic microorganisms carried by synanthropic flies caught at different rural locations in germany human pathogens in body and head lice clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: update by the infectious diseases society of america tackling contamination of the hospital environment by methicillin-resistant staphylococcus aureus (mrsa): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination richtlinie der Österreichischen gesellschaft für hygiene, mikrobiologie und präventivmedizin (Öghmp) für apparate zur automatischen dosierung flüssiger chemischer desinfektionsmittel mupirocin and chlorhexidine resistance in staphylococcus aureus in patients with community -onset skin and soft tissue infections the repetitive irritation test (rit) with a set of standard irritants surgical site infections and the surgical care improvement project (scip): evolution of national quality measures randomized, multicenter trial of antibiotic prophylaxis in elective colorectal surgery: single dose vs doses of a second-generation cephalosporin without metronidazole and oral antibiotics how often do you wash your hands? a review of studies of hand-washing practices in the community during and after the sars outbreak in effect of quinolone prophylaxis in afebrile neutropenic patients on microbial resistance: systematic review and meta-analysis antibiotic prophylaxis for bacterial infections in afebrile neutropenic patients following chemotherapy . cochrane database syst rev systematic patients' hand disinfection: impact on meticillin-resistant staphylococcus aureus infection rates in a community hospital microbial monitoring of the hospital environment: why and how? surgical site infection in 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series and review of the literature the science behind stable, super-oxidized water do antibiotic-impregnated catheters prevent infection in csf diversion procedures? review of the literature hand-to-hand transmission of rhinovirus colds interruption of experimental rhinovirus infection medizinische bedeutung und bekämpfung . in: aspöck h (hsg .) krank durch arthropoden treating infected diabetic wounds with superoxidized water as antiseptic agent: a preliminary experience nosokomiale infektionen bei frühgeborenen -umsetzung der krinko-empfehlungen im deutschen frühgeborenennetzwerk effect of hand sanitizer use on elementary school absenteeism antibiotic stewardship formaldehyde sterilisation, i determination of formaldehyde residuals in autoclavesterilized materials formaldehyde sterilisation, ii formaldehyde sterilisation, the process and the influence on the formaldehyde residuals formaldehyde sterilisation, iii the behaviour of the loaded autoclaves and the permeability of plastic materials to formaldehyde chemical inactivation of hiv on surfaces outbreak of enterobacter cloacae related to understaffing, overcrowding, and poor hygiene practices public health significance of urban pests . world health organization concentration of bacteria passing through puncture holes in surgical gloves wann sollte in operationsräumen ein wechsel chirurgischer handschuhe erfolgen? reduction in hospital-wide incidence of infection or colonization with methicillin-resistant staphylococcus aureus with use of antimicrobial hand hygiene gel and statistical process control charts Étude risque-bénéfice de l'usage des aldéhydes comme désinfectants à l'hôpital novel pyrogen tests based on the human fever reaction carcinogenicity study of sodium hypochlorite in f rats evaluating central venous catheter care in a pediatric intensive care unit surgical infection society guideline: prophylactic antibiotic use in open fractures: an evidence-based guideline comparison of the microbiological 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cefamandole nafate in elective orthopedic surgery zur inaktivierenden wirkung organischer säuren auf parvoviren bei verschiedenen temperaturen hessische verwaltung für bodenmanagement und geoinformation (hvbg) low infection rate after tumor hip rthroplasty for metastatic bone disease in a cohort treated with extended antibiotic prophylaxis use of alcohol hand sanitizer as an infection control strategy in an acute care facility hsg .) public health significance of urban pests . world health organization high rate of qaca -and qacb -positive methicillin -resistant staphylococcus aureus isolates from chlorhexidine -impregnated catheter -related bloodstream infections use of chlorhexidine-impregnated dressing to prevent vascular and epidural catheter colonization and infection: a meta-analysis schadwirkungen durch tierische gesundheitsschädlinge, insektizide und akarizide (allergieverursachung, sachgerechte bekämpfung sowie arbeits-und betroffenenschutzmaßnahmen) public health significance of urban pests . world health organization reduced susceptibility to chlorhexidine in staphylococci: is it increasing and does it matter? polyhexamethylene biguanide: two year feeding study in rats . study performed by zeneca central toxicology laboratory practice guideline adherence and health care outcomesuse of prophylactic antibiotics during surgery in taiwan strategies for the prevention of central venous catheter infections: an american pediatric surgical association outcomes and clinical trials committee systematic review risk of acquiring antibiotic-resistant bacteria from prior room occupants targeted versus universal decolonization to prevent icu infection review on the efficacy, safety and clinical applications of polihexanide, a modern wound antiseptic octenidine dihydrochloride, a modern antiseptic for skin, mucous membranes and wounds effectiveness of alcohol-based hand disinfectants in a public administration: impact on health and work performance related to acute respiratory symptoms and diarrhoea survival of bacterial pathogens on paper and bacterial retrieval from paper to hands . preliminary results the durability of examination gloves used on intensive care units einsatz textiler aufbereitbarer unterziehhandschuhe für medizinische tätigkeiten: eine machbarkeitsstudie prospective randomized trial of % povidone-iodine versus . % tincture of chlorhexidine as cutaneous antisepsis for prevention of central venous catheter infection in vivo microdialysis to measure antibiotic penetration into soft tissue during cardiac surgery chlorhexidine and chondrolysis in the knee chlorhexidine and chondrolysis in the knee fluoroquinolone prophylaxis in patients with neutropenia: a meta-analysis of randomized placebo-controlled trials international agency for research and cancer . iarc classifies formaldehyde as carcinogenic to humans: press release: n° effect of antimicrobial prophylaxis on the incidence of infections in clean surgical wounds in hospitals undergoing renovation antibiotic prophylaxis for transrectal biopsy of the prostate: a prospective randomized study of the prophylactic use of single dose oral fluoroquinolone versus trimethoprim-sulfamethoxazole -sterilization of health care products -dry heat -requirements for the development, validation and routine control of a sterilization process for medical devices effect of body mass index and ertapenem versus cefotetan prophylaxis on surgical site infection in elective colorectal surgery risk factors for infection after knee arthroplasty . a registerbased analysis of cases antimicrobial prophylaxis for contaminated head and neck surgery efficacy of an alcohol/chlorhexidine hand hygiene program in a hospital with high rates of noso-comial methicillin-resistant staphylococcus aureus (mrsa) infection prospective, controlled study of vinyl glove use to interrupt clostridium difficile nosocomial transmission zur viruziden wirksamkeit chemischer und physikalischer 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application time and hand coverage in hygienic hand disinfection improving patient safety during insertion of peripheral venous catheters: an observational intervention study effective reprocessing of reusable dispensers for surface disinfection tissues -the devil is in the details poorly processed reusable surface disinfection tissue dispensers may be a source of infection single-dose oral ciprofloxacin versus placebo for prophylaxis during transrectal prostate biopsy evaluation of effect and comparison of superoxidised solution (oxum) v/s povidone iodine (betadine) impact of non-rinse skin cleansing with chlorhexidine gluconate on prevention of healthcare -associated infections and colonization with multi-resistant organisms: a systematic review antibiotic prophylaxis and the risk of surgical site infections following total hip arthroplasty: timely administration is the most important factor epidemiologie und ursachen mikrobieller biozidresistenzen comparison of etiology and rate of infection in different surgical wounds chlorhexidine impregnated central venous catheter inducing an anaphylatic shock in the intensive care unit the modification of high-dose therapy shortens the duration of neutropaenia by delay of leucocyte nadir zur bedeutung der listen bekannt gemachter mittel und verfahren für behördlich angeordnete entseuchungen bekämpfung von wirbeltieren aufgrundlage des § infektionsschutzgesetz disinfection, sterilization and preservation, . aufl . philadelphia: lea & febiger outcomes of prophylactic antibiotics following surgery for zygomatic bone fractures einfluss der fußbodendesinfektion auf die mikrobielle und partikulare belastung der raumluft in augen-op-räumen mit verdrängungslüftungsbereichen standardized comparison of antiseptic efficacy of triclosan, pvp-iodine, octenidine dihydrochloride, polyhexanide and chlorhexidine digluconate decontamination of room air and adjoining wall surfaces by nebulizing hydrogen peroxide reinigung und desinfektion von eßgeschirr, instrumenten und ausscheidungsbehältern im krankenhaus wallhäußers praxis der sterilisation, desinfektion, antiseptik und konservierung . . auflage kramer a, assdian o (hrsg,), wallhäußers praxis der sterilisation, desinfektion, antiseptik und konservierung . . auflage . stuttgart kommission für krankenhaushygiene und infektionsprävention am robert koch-institut . anforderungen der hygiene bei operationen und anderen invasiven eingriffen ausbruchmanagement und strukturiertes vorgehen bei gehäuftem kommission für krankenhaushygiene und infektionsprävention (krinko) am robert koch-institut (rki) kommission für krankenhaushygiene und infektionsprävention (krinko) am robert koch-institut . prävention postoperativer infektionen im operationsgebiet kommission für krankenhaushygiene und infektionsprävention (krinko) am robert koch-institut . anforderungen an die hygiene bei der medizinischen versorgung von immunsupprimierten patienten anforderungen an die hygiene bei der aufbereitung von medizinprodukten kommission für krankenhaushygiene und infektionsprävention (krinko) am robert koch-institut . hygienemaßnahmen bei infektionen oder besiedlung mit multiresistenten gramnegativen stäbchen kommission für krankenhaushygiene und infektionsprävention (krinko) am robert koch-institut . prävention der nosokomialen beatmungsassoziierten pneumonie end-of-procedure cefazolin concentrations after administration for prevention of surgical-site infection risk factors for adult nosocomial meningitis after craniotomy role of antibiotic prophylaxis integrity of vinyl and latex procedures gloves hand disinfection and antiseptic of skin, mucous membranes, and wounds kramer a, assadian o, hrsg . wallhäußers praxis der sterilisation, desinfektion, antiseptik und konservierung . qualitätssicherung der hygiene in medizinischen und industriellen bereichen use of biocidal surfaces for reduction of healthcare acquired infections prophylactic use of topical antiinfectives in ophthalmology hand rub-associated fire incidents during hospital-years in germany wallhäußers praxis der sterilisation, desinfektion, antiseptik und konservierung . stuttgart: thieme perioperative antibiotikaprophylaxedominierende möglichkeit zu infektionsprophylaxe bei chirurgischen eingriffen? health risks of surface disinfection in households with special consideration on quaternary ammonium compounds (qacs) mycotoxins in indoor and outdoor environments and human health how long do nosocomial pathogens persist on inanimate surfaces? a systematic review klinische antiseptik zielsetzung und möglichkeiten der antiseptik im genitalbereich explantationstest mit haut und peritoneum der neonatalen ratte als voraussagetest zur verträglichkeit lokaler antiinfektiva für wunden und körperhöhlen mitteilung der kommission für krankenhaushygiene und infektionsprävention am robert koch-institut limited efficacy of alcohol-based hand gels toxikologische bewertung für die händedesinfektion 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trial of povidoneiodine, alcohol, and chlorhexidine for prevention of infection associated with central venous and arterial catheters use of audit tools to evaluate the efficacy of cleaning systems in hospitals probleme bei der biologischen testung von gas-sterilisatoren public health significance of urban pests . world health organization strategies to prevent central line-associated bloodstream infections in acute care hospitals: update the gastrointestinal tract . the "undrained abscess" of multiple organ failure a preliminary investigation of the microbiology endotoxin content in the water reservoirs of bench top non-vacuum autoclaves international and specialty trends in the use of prophylactic antibiotics to prevent infectious complications after insertion of external ventricular drainage devices antiseptics and disinfectants: activity, action, and resistance ad hoc clostridium difficile surveillance working group . recommendations for surveillance of clostridium 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schwerstverbrannten the pathogenesis and epidemiology of catheter-related infection with pulmonary artery swan-ganz catheters: a prospective study utilizing molecular subtyping what is the predominant source of intravascular catheter infections? area fumigation with hydrogen peroxide vapor antibiotic consumption and resistance: data from europe and germany randomized controlled trial and cost-effectiveness analysis of silver-donating antimicrobial dressings for venous leg ulcers (vul-can trial) polyhexamethylene biguanide: two year oncogenicity study in mice . study performed by zeneca central toxicology laboratory reducing picu central line-associated bloodstream infections: -year results central line-associated bloodstream infection prevention daily chlorhexidine bathing to reduce bacteraemia in critically ill children: a multicentre, cluster-randomised, crossover trial prospective, randomized trial of two antiseptic solutions for prevention of central venous or arterial catheter colonization and infection in intensive care unit patients molecular revolution in the diagnosis of microbial brain abscesses surgical glove perforation and the risk of surgical site infection levofloxacin resistant escherichia coli sepsis following an ultrasound-guided transrectal prostate biopsy: report of four cases and review of the literature prophylactic and local applications of antimicrobials in endodontics: an update review primary central nervous system lymphoma treated with high-dose methotrexate, high-dose busulfan/thiotepa, autologous stem-cell transplantation and response-adapted whole-brain radiotherapy: results of the multicenter ostdeutsche studiengruppe hamato-onkologie osho- phase ii study biological toxicity of acid electrolysed functional water: effect of oral administration on mouse digestive tract and changes in body weigth analysis of complications in consecutive pediatric patients treated with intrathecal baclofen therapy: -year experience the role of postoperative antibiotics in facial fractures: comparing the efficacy of a -day versus a prolonged regimen . the journal of trauma and acute care surgery safety and impact of chlorhexidine antisepsis interventions for improving neonatal health in developing countries nosokomiale sepsis bei sehr kleinen frühgeborenen -diagnostik und therapie residual antimicrobial effect of chlorhexidine digluconate and octenidine dihydrochloride on reconstructed human epidermis comparative study of in vitro cytotoxicity of povidoneiodine in solution, in ointment, or in a liposomal formulation (repithel ® ) and selected antiseptics biocompatibility index of antiseptic agents by parallel assessment of antimicrobial activity and cellular cytotoxicity interaction of octenidine and chlorhexidine with mammalian cells and the resulting microbicidal effect (remanence) of the combinations finding a benchmark for monitoring hospital cleanliness prevention of bloodstream infections by use of daily chlorhexidine baths for patients at a long-term acute care hospital use of uv powder for surveillance to improve environmental cleaning bed bugs in healthcare settings progressive ulzerative keratitis related to the use of topical chlorhexidine gluconate ( . %) isolation precautions for the prevention of the transmission of ebola, enterovirus-d and other infectious agents in healthcare settings in vitro activity and concentrations in serum, urine, prostatic secretion and adenoma tissue of ofloxacin in urological patients surveillance study in europe and brazil on clinical aspects and antimicrobial resistance epidemiology in females with cystitis ( aresc): implications for empiric therapy use of quinolones in urinary tract infections and prostatitis increasing hospital admission rates for urological complications after transrectal ultrasound guided prostate biopsy stand und perspektiven der antibiotika-prophylaxe bei patienten mit künstlichem gelenkersatz primary prophylaxis of bacterial infections and pneumocystis jirovecii pneumonia in patients with hematological malignancies and solid tumors : guidelines of the infectious diseases working party (agiho) of the german society of hematology and oncology (dgho) désinfection par voie aérienne : une norme pour sonder la qualité des produits antibiotic prophylaxis in surgery - and beyond orthopedic surgical site infections: analysis of causative bacteria and implications for antibiotic stewardship antimicrobial prophylaxis in surgery: the role of pharmacokinetics late infections after allogeneic bone marrow transplantations: comparison of incidence in related and unrelated donor transplant recipients polihexanide carcinogenicity: analysis of human health risk . prepared for the australian pesticides and veterinary medicines authority guidelines for the prevention of intravascular catheter-related infections . the hospital infection control practices advisory committee, center for disease control and prevention guidelines for the prevention of intravascular catheterrelated infections mediastinal irrigation with superoxidized water after open heart surgery: the safety and pitialls of cardiovascular surgical applications the efficacy of daily bathing with chlorhexidine for reducing healthcare-associated bloodstream infections: a meta-analysis . infect contr hsg .) public health significance of urban pests regulatory action criteria for filth and other extraneous materials . iii . review of flies and foodborne enteric disease the effectiveness of single-dose fosfomycin as antimicrobial prophylaxis for patients undergoing transrectal ultrasound-guided biopsy of the prostate efficacy and effectiveness of influenza vaccines . a systematic review and meta-analysis expertisen-verzeichnis der Österreichische gesellschaft für hygiene, mikrobiologie und präventivmedizin hygiene-richtlinien für krankenhauswäsche bearbeitende wäschereien surgical site infection rates after minimally invasive spinal surgery bakterien in sekreten extra-und intraoraler operationswunden kontamination oder infektion? hydrogen peroxide vapor decontamination of an intensive care unit to remove environmental reservoirs of multidrug-resistant gramnegative rods during an outbreak selection for qaca carriage in cc , but not cc , methicillin-resistant staphylococcus aureus bloodstream infection isolates during a successful institutional infection control programme the role of contaminated surfaces in the transmission of nosocomial pathogens the survival of influenza a(h n )pdm virus on household surfaces incidence of acute prostatitis caused by extended-spectrum beta-lactamase-producing escherichia coli after transrectal prostate biopsy mutagene potenz von wofasteril, wofasept, formaldehyd, chlorhexidin und bronopol im knochenmark an der maus adherence to surgical site infection guidelines in italian cardiac surgery units quality of perioperative chemoprophylaxis in obstetrics and gynecology: preliminary results of asppoc in greece and italy incidence of microperforation for surgical gloves depends on duration of wear efficacy of antibiotic-impregnated cement in total hip replacement . a meta-analysis effect of glutaraldehyde on the antigenicity and infectivity of hepatitis a virus an evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms prospective, randomized, double-blind study comparing single-agent antibiotic therapy, ciprofloxacin, to combination antibiotic therapy in open fracture wounds vestibular and cochlear ototoxicity of topical antiseptics assessed by evoced potentials etiology and mortality of spontaneous bacterial peritonitis in liver transplant recipients: a cohort study prophylactic chemotherapy with fosfomycin trometamol salt during transurethral prostatic surgery: a controlled multicenter clinical trial associations for surgical research, angers and colombes, france . risk factors for prediction of surgical site infections in "clean surgery perioperative antibiotikaprophylaxe in der chirurgie vergleichende untersuchungen zur resistenz von mycobacterium terrae untersuchungen zur prüfung der viruziden wirksamkeit von desinfektionsmitteln für die chemische instrumentendesinfektion . . mitteilung: vergleich der ergebnisse von suspensionsversuchen und praxisnaher prüfung zur prüfung der viruziden wirksamkeit von flächendesinfektionsmitteln surgical site infections surveillance in neurosurgery patients use of a -piece chlorhexidine gluconate transparent dressing on critically ill patients university of minnesota, department of food science and nutrition and school of public health anaphylaxis to chlorhexidine . case report . implication of immunoglobulin e antibodies and identification of an allergenic determinant the integrity of latex gloves in clinical dental practice effectiveness of a hospital-wide program to improve compliance with hand hygiene learning, techniques, and complications of endoscopic ultrasound (eus)-guided sampling in gastroenterology core elements of hospital antibiotic stewardship programs from the centers for disease control and prevention comparison of infection rate with the use of antibiotic-impregnated vs standard extraventricular drainage devices: a prospective, randomized controlled trial effectiveness of routine patient cleansing with chlorhexidine gluconate for infection prevention in the medical intensive care unit relationship between chlorhexidine gluconate skin concentration and microbial density on the skin of critically ill patients bathed daily with chlorhexidine gluconate chemical inactivation of viruses . dissertation, univ . missouri dictyoptera, blattodea) -ihre bedeutung als Überträger von krankheitserregern und als verursacher von allergien . in: aspöck h (hrsg .) . krank durch arthropoden prophylactic antibiotics in orthopaedic surgery translating evidence into practice: a model for large scale knowledge translation an intervention to decrease catheter-related bloodstream infections in the icu sustaining reductions in catheter related bloodstream infections in michigan intensive care units: observational study prevention and management of ventriculoperitoneal shunt infections in children psa-benutzungsverordnung vom . dezember complication rates and risk factors of transrectal ultrasound-guided sextant biopsies of the prostate within a populationbased screening program high infection rate outcomes in long-bone tumor surgery with endoprosthetic reconstruction in adults: a systematic review bestimmung der keimzahl und kinetik der keimeliminierung bei bakteriämie nach zahnentfernung carriage by the housefly (musca domestica) of multiple-antibiotic-resistant bacteria that are potentially pathogenic to humans, in hospital and other urban environments in misurata antibiotic prophylaxis for surgical introduction of intracranial ventricular shunts: a systematic review definition der desinfektion a simple method to reduce infection of ventriculoperitoneal shunts ein neues therapiekonzept bei skabies alcohols for skin antisepsis at clinically relevant skin sites an innovative tropical drug formulation for wound healing and infection treatment: in vitro and in vivo investigations of a povidone iodine liposome hydrogel effectiveness of antibiotic prophylaxis in third molar surgery: a meta-analysis of randomized controlled clinical trials richtlinie / /eg, bekanntmachungen im amtsblatt der europäischen union juni (abl . eg nr . l s . ) zuletzt geändert durch artikel der richtlinie richtlinie / /ewg über medizinprodukte, bekanntmachungen im amtsblatt der richtlinie / /eg über druckgeräte, bekanntmachungen im amtsblatt der europäischen union richtlinien des bundesausschusses der Ärzte und krankenkassen über die ärztliche betreuung während der schwangerschaft und nach der entbindung ciprofloxacin versus gentamicin in prophylaxis against bacteremia in transrectal prostate needle biopsy richtlinie des robert koch-institutes zur prüfung der wirksamkeit von flächendesinfektionsmitteln bei tuberkulose und . der richtlinie für krankenhaushygiene und infektionsprävention -anforderungen der hygiene an die wäsche aus einrichtungen des gesundheitsdienstes, die wäscherei und den waschvorgang richtlinie des robert koch-institutes zur prüfung der wirksamkeit von desinfektionsmitteln für die chemische instrumentendesinfektion bei tuberkulose (stand . . ) richtlinie des robert koch-instituts zur prüfung der viruzidie von chemischen flächendesinfektionsmitteln und instrumentendesinfektionsmitteln, die in die liste gemäß § c des bundesseuchengesetzes aufgenommen werden sollen, fassung vom . märz empfehlungen der kommission für krankenhaushygiene und infektionsprävention empfehlung zur prüfung und deklaration der wirksamkeit von desinfektionsmittel gegen viren liste der vom robert koch-institut geprüften und anerkannten desinfektionsmittel und -verfahren biopatch -a new 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medizinprodukte) . rote liste service gmbh effect of antiseptic wound irrigation of traumatic soft tissue wounds on postinterventional wound infection rates -a longitudinal mono-centre cohort study hospital epidemiology and infection control antibiotic prophylaxis in colorectal surgery antimicrobial suture wound closure for cerebrospinal fluid shunt surgery: a prospective, double-blinded, randomized controlled trial die wissenschaftlichen grundlagen einer desinfektion durch vereinigte wirkung gesättigter wasserdämpfe und flüchtigen desinfektionsmitteln bei künstlich erniedrigtem luftdruck leipzig und wien: verlag franz deuticke nosocomial and community-acquired infections in germany . summary of the results of the first national prevalence study (nidep) aasld practical guideline: management of adult patients with ascites due to cirrhosis: update prospective, controlled, cross-over trial of alcohol-based hand gel in critical care units prevention of central venous catheter related infections with chlorhexidine gluconate impregnated wound dressings: a randomized controlled trial bacterial resistance to antiseptics and disinfectants possible link between bacterial resistance and use of antibiotics and biocides public health significance of urban pests . world health organization meta-analysis: methods for diagnosing intravascular device related bloodstream infection species-level assessment of the molecular basis of fluoroquinolone resistance among viridans group streptococci causing bacteraemia in cancer patients measuring hand hygiene compliance: a new frontier for improving hand hygiene the importance of leadership in preventing healthcare-associated infection: results of a multisite qualitative study superficial and deep sternal wound infection after more than koronary artery bypass graft (cabg): incidence, risk factors and mortality the biocide triclosan selects stenotrophomonas maltophilia mutants that overproduce the smedef multidrug efflux pump a randomized, controlled trial of a multifaceted intervention including alcohol-based hand sanitizer and hand-hygiene education to reduce illness transmission in the home nosocomial serratia marcescens infections associated with extrinsic contamination of a liquid nonmedicated soap sensitivity of human adenoviruses to different groups of chemical biocides sensitivity of poliovirus type and echovirus type to different groups of chemical biocides detection of varicella-zoster virus dnain air samples from hospital rooms microbicidal efficacy of pvp-iodine, chlorhexidine digluconate, polyhexanide and octenidine dihydrochloride in the quantitative carrier test according to en (phase /step ) external ventricular and lumbar drainage-associated meningoventriculitis: prospective analysis of time-dependent infection rates and risk factor analysis reduction of central venous line-associated bloodstream infection rates by using a chlorhexidine-containing dressing human bocavirus: passenger or pathogen in acute respiratory tract infections? pathogenesis, virulence, and infective dose die immunpathogenese der sepsis empfehlung des vah zu formaldehyd (nach anhörung der desinfektionsmittelkommission) antibiotika-verbrauchs surveillance schweizerisches heilmittelinstitut (swissmedic) a systematic review of intraoperative warming to prevent postoperative complications antibiotic prophylaxis in surgery -sign -a national clinical guideline grenzen klinischer behandlungspfade . die implantat-assoziierten infektionen epidemiologie multiresistenter erreger bei auslandsreisenden bacterial colonization of bar soaps and liquid soaps in hospital environments antibiotic prophylaxis in clean neck dissections scabies and bed bugs in hospital outbreaks central venous catheter-related bloodstream infections: improving post-insertion catheter care effect of risk-stratified, protocol-based perioperative chemoprophylaxis on nososcomial infection rates in a series of . consecutive neurosurgical 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der keimträger verfälscht die dampfresistenz von bioindikatoren bacillus subtilis und bacillus stearothermophilus als testkeime von bioindikatoren: abhängigkeit der resistenz gegenüber wasserdampf von den eigenschaften des keimträgers epidemiological role of arthropods detectable in health facilities in: aspöck h (hsg .) krank durch arthropoden die wirksamkeit der formaldehyd-gas-sterilisation bei °c im vergleich zu °c timing of antimicrobial prophylaxis and the risk of surgical site infections: results from the trial to reduce antimicrobial prophylaxis errors impact of octenidine on phagocytosis of staphylococcus aureus by neutrophils das murine norovirus -ein neues surrogatvirus für die humanen noroviren leitfaden der desinfektion, sterilisation und entwesung the use of prophylactic flucloxacillin in treatment of open fractures of the distal phalanx within an accident and emergency department: a double-blind randomized placebo-controlled trial occupational hand dermatitis in hospital 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and keratinocytes bacterial pathogens use of antibacterial prophylaxis in patients with chemotherapy-induced neutropenia antibiotic concentrations in the abdominal cavity as basis for antibacterial therapy of peritonitis: penetration of mezlocillin into the peritoneal exudate murine norovirus: a model system to study norovirus biology and pathogenesis ivermectin als orale einmalbehandlung der scabies antibiotics-impregnated ventricular catheter versus systemic antibiotics for prevention of nosocomial csf and non-csf infections: a prospective randomized clinical trial regional office for europe . guidelines for indoor air quality: selected pollutants . , kopenhagen, dänemark . world health organization . who guidelines on hand hygiene in health care . first global patient safety challenge clean care is safer care sepsis due to fluoroquinolone-resistant escherichia coli after transrectal ultrasound-guided prostate needle biopsy efficacy of antimicrobial-impregnated external ventricular drain catheters: a prospective, randomized, controlled trial antibiotic prophylaxis for transrectal prostate biopsy . cochrane database syst rev a prospective, randomized, double-blind study of single high dose versus multiple standard dose gentamicin both in combination with metronidazole for colorectal surgical prophylaxis antibiotic pharmacodynamics in surgical prophylaxis: an association between intraoperative antibiotic concentrations and efficacy molecular investigation of bacterial communities on the inner and outer surfaces of peripheral venous catheters molecular investigation of bacterial communities on intravascular catheters: no longer just staphylococcus impact of a prevention strategy targeting hand hygiene and catheter care on the incidence of catheter-related bloodstream infections hospital-wide multidisciplinary, multimodal intervention programme to reduce central venous catheter-associated bloodstream infection impact of bordetella pertussis exposures on a massachusetts tertiary care medical system operative sanierung florider venöser ulcera -wundinfektionsrate unter antibiogramm-orientierter perioperativer prophylaxe krankheitsübertragung: von herausragender bedeutung für effektivität der mechanischen erregerverbreitung ist der anpassungsgrad (synanthropiegrad) eines hygieneschädlings an den menschlichen siedlungsbereich, da dieser das ausmaß des kontinuierlichen erregerkontakts zwischen kontaminationsort und behandlungs-, wohn-und/oder arbeitsumfeld bestimmt (faulde und freise ) . vor allem in sensiblen bereichen wie krankenhäusern und großküchen ist die mechanische erregerverschleppung bedeutsam (sramova et al. ). besondere relevanz bei der Übertragung von ni haben passive vektoren, wenn sie multi-oder sogar panresistente, fakultativ oder obligat humanpathogene erreger großflächig verbreiten und gleichzeitig die verfügbare erregermenge durch vermehrung z. b. im gastrointestinaltrakt erhöhen (faulde und freise ; sramova et al. ) .multiresistente humanpathogene bakterien an synanthropen arthropoden konnten innerhalb bzw. in unmittelbarer nähe von krankenhäusern in deutschland, libyen, in afrika südlich der sahara sowie in indien an fliegen, schaben und an der schmetterlingsmücke clogmia albipunctata nachgewiesen werden (boulesteix et al. ; faulde und spiesberger ; rahuma et al. ; tilahun et al. key: cord- -o e na authors: nan title: scientific session of the th world congress of endoscopic surgery, jointly hosted by society of american gastrointestinal and endoscopic surgeons (sages) & canadian association of general surgeons (cags), seattle, washington, usa, – april : poster abstracts date: - - journal: surg endosc doi: . /s - - - sha: doc_id: cord_uid: o e na nan purpose: to evaluate the efficacy of single-incision laparoscopic surgery for totally extraperitoneal repair (sils-tep) of incarcerated inguinal hernia. patients and methods: clinical setting a retrospective analysis of patients undergoing sils-tep for incarcerated hernia from may to august at kinki central hospital was performed. exclusion criteria sils-tep was contraindicated for the following conditions in our hospital: a history of radical prostatectomy; a small indirect inguinal hernia in a young patient; and unsuitable for general anesthesia. surgical procedure laparoscopic abdominal exploration through a single, . -cm, intraumbilical incision was performed. the incarcerated hernia content was gently retracted from the hernia sac into the abdominal cavity. in some cases, simultaneous manual compression on the incarcerated hernia from the body surface was required. if no bowel resection was needed, a standard sils-tep using mesh was performed following laparoscopic abdominal exploration and incarcerated hernia reduction. if bowel resection was required, inguinal hernia repair using mesh was not performed to avoid postoperative mesh infection, and two-stage sils-tep was performed - months after the bowel resection. results: fourteen patients ( men, women) with irreducible inguinal hernias, including with unilateral hernias and with bilateral hernias, underwent surgery. the patients' median age was years (range, - years), and median bmi was . kg/m (range, . - . kg/m ). of the patients, had acute incarceration, and had a chronic irreducible hernia. seven patients with acute incarcerated hernias underwent emergency surgery, and two of the seven patients needed singleincision laparoscopic partial resection of the ileum, followed by two-stage sils-tep. twelve patients, excluding two patients who required single-incision laparoscopic partial resection of the ileum, underwent laparoscopic exploration with hernia reduction followed by sils-tep. one case of chronic incarceration out of the twelve patients who underwent sils-tep after hernia reduction required conversion to kugel patch repair. the median operative times were min (range - min) for unilateral hernias and min (range - min) for bilateral hernias. the median blood loss was minimal (range - ml). the median postoperative hospital stay was day (range - days). the median follow-up period was months (range - months). a seroma developed in % ( / ) of patients and was managed conservatively. no other major complications or hernia recurrence were noted during the follow-up period. conclusions: sils-tep, which offers good cosmetic results, could be safely performed for incarcerated inguinal hernia. objective: introduction of mis in pediatric age group has been proved feasible and safe. there is considerable evolution with introduction of a number of invovation in mis pediatric inguinal hernia repair. high ligation of sac is the basic premise of surgical repair in pediatric inguinal hernias. there are different mis techniques broadly grouped into intracorporeal or intracorporeal with extracorporeal component namely the suturing. every techniques has its own complications. the main objective of our study was to focus on different anatomical pointers which can lead inadverent complications mainly bleeding and recurrence. methods and procedures: prospective review of hernias ( male and female) ( months- years) performed laparoscopically between september and june . under laparoscopic guidance, the internal ring was encircled extraperitoneally using a - non-absorbable suture and knotted extraperitoneally. data analyzed included operating time, ease of procedure, occult patent processus vaginalis (ppv), contralateral inguinal hernia, complications, cosmesis and recurrence. results: sixteen right ( %), left ( %) and bilateral hernia ( %) were repaired. five unilateral hernias ( . %), all left, had a contralateral ppv that was repaired (p= . ). mean operative time for a unilateral and bilateral repair were . ( - ) and . min ( - min) respectively. one hernia repair still recurred ( . %) even with all precautions and another had a post operative hydrocoele ( . %). one case ( . %) needed an additional port placement due to inability to reduce the contents of hernia completely. because of our techinique we could not find any adverent peroperative bleeding. there were no stitch abscess/granulomas, obvious spermatic cord injuries, testicular atrophy, or nerve injuries. conclusion: the results confirm safety, efficacy and cost effectiveness of laparoscopic inguinal hernia repair. during our per-operative analysis we focus to address the anatomical landmark to minimize future recurrence and peroperative surgical complications. we identified and named a point as j. point at the tip of triangle of "doom". that is most important point to address peroperatively. there is high chance of recurrence if that point is not encircled well or inadequately circled because of fear of iliac vessels injury. we aslo concluded that 'water dissection technique' is effective techniques in un-experienced hand and in early stages of laparoscopic hernia repair to prevent inadvertent iliac vessels injury. medstar georgetown university hospital, georgetown university school of medicine, introduction: incisional hernias following abdominal surgery can be associated with significant morbidity leading to decreased quality of life, increase in health care spending and need for repeat operations. patients undergoing gastrointestinal and hepatobiliary surgery for malignant disease may be at higher risk for developing incisional hernias. identifying these risk factors for incisional hernia development can help decrease occurrence. this will be the largest multi-institutional study looking at incidence of symptomatic hernia rates for major abdominal operations including colectomy, hepatectomy, pancreatectomy, and gastrectomy. methods and procedures: an irb-approved retrospective study within the medstar hospital database was conducted, incorporating all isolated colectomy, hepatectomy, pancreatectomy, and gastrectomy procedures performed across hospitals between the years of to . all patients were identified using icd- and icd- codes for relevant procedures and then subdivided into either having benign or malignant disease. exclusion criteria comprised of patients who had concomitant organ resection, or those undergoing organ transplant. data validation was performed to verify the accuracy of the data set. the rate of symptomatic incisional hernia rates (ihrs) were determined for each cohort based on subsequent hernia procedural codes identified and repairs performed. descriptive statistics and chi squared test were used to report ihrs in each group. results: during this -year span, a total of , major abdominal operations were performed at all institutions, comprising of , colectomies, , hepatectomies, , pancreatectomies, and gastrectomies. malignancy was the indication for surgery in , ( . %) colectomies, ( . %) hepatectomies, ( . %) pancreatectomies, and ( . %) gastrectomies. ihr in each cohort for benign vs malignant etiologies, respectively, are as follows: ( . %) vs ( . %) in colectomy (p= . ), ( . %) vs ( . %) in hepatectomy (p= . ), ( . %) vs ( . %) in pancreatectomy (p= . ), and ( . %) vs ( . %) in gastrectomy (p= . ) patients. conclusion: symptomatic incisional hernia rates following major gastrointestinal and hepatobiliary surgery ranges from . to . %. there was no significant increase in hernia rates in patients undergoing surgery for malignancy. patients undergoing colectomy for benign disease had a high incidence of symptomatic ihrs. introduction: prosthetic infections, although relatively uncommon, are a major source of cost and morbidity. the study aimed to evaluate the influence of mesh structure including the polymer type and mean pore size on bacterial adherence in a mouse model. methods: three commercially available hernia meshes were included in the study. for each mesh type, a cm square was surgically placed intraabdominally in mice. one mouse served as a control while an enterotomy was made in the subsequent mice to introduce a bacterial load onto the mesh. after hours the meshes were harvested. the inoculated meshes were then plated on agar plates and bacterial counts were counted after hours. the bacterial counts were compared between the various mesh types. results: the mean bacterial adherence was increased in the large pore mesh was colonies, for the small pore mesh was colonies, and in the biologic mesh group it was colonies. conclusions: through the use of a mouse model, the influence of mesh type and pore size on bacterial adherence was evaluated. meshes that have larger pores with a lower prosthetic load and the biologic mesh interestingly had lower early bacterial colonization after hours following an enterotomy. further evaluation with a longer incubation time could be helpful to determine the effect of bacterial colonization of mesh. hrishikesh salgaonkar, raquel maia, lynette loo, wee boon tan, sujith wijerathne, davide lomanto; national university hospital, singapore laparoscopic repair of groin hernias is widely accepted approach over open due to lesser pain, faster recovery, better cosmesis and decreased morbidity. however, there is still debate on its use in large inguino-scrotal hernias, recurrent hernias and history of lower abdominal surgery anticipating adhesions and difficulty in dissecting extensive hernia sac. retrospective analysis of prospectively collected data was done of patients undergoing laparoscopic repair of large inguino-scrotal, incarcerated groin hernia, recurrent cases after open or laparoscopic repair and history of previous lower abdominal surgery. between january to july , patients with large inguino-scrotal hernias, recurrent hernia, history of lower abdominal surgery, incarcerated femoral hernia underwent laparoscopic inguinal hernia repair. patient characteristics, operating time, surgical technique, conversion rate, complications and recurrence up to months recorded. patients had large inguino-scrotal hernia, recurrent hernia ( previous open, previous lap) , history of lower abdominal surgery ( lscs, appendectomy, prostatectomy, midline laparotomy), incarcerated femoral hernia, meshoma removal. patients underwent total extraperitoneal (tep) repair, transabdominal pre-peritoneal (tapp), needed conversion to open. mean operation time was min for unilateral and min for bilateral hernia. seroma formation seen in patients, minor wound infections treated conservatively. we conclude that the laparoscopic approach can be safely employed for the treatment of complex groin hernias; surgical experience in laparoscopic hernia repair is mandatory with tailored technique in order to minimize morbidity and achieve good clinical outcomes with acceptable recurrence rates. mesh fixation in ventral incisional hernia is a topic of ongoing debate. permanent and absorbable tacks are acceptable and widely used methods for mesh fixation. the purpose of this study was to compare outcomes of permanent tack fixation versus absorbable when used alone or with suture fixation in laparoscopic incisional hernia repairs. a retrospective review of all patients undergoing laparoscopic ventral hernia using tack fixation (absorbable/permanent) alone or in conjunction with suture fixation was queried from the ahsqc database. outcome measures included hernia recurrence rate, pain, quality of life, wound related issues, and hospital length of stay. propensity match scoring was performed to compare patients undergoing tack only fixation versus tack and suture fixation with a p-value of . considered significant. a total of patients were identified after propensity match scoring with who underwent repair with permanent tacks alone or with sutures and who underwent repair with absorbable tacks alone or with sutures. following matching there were no differences in bmi, age, hernia width/length, or baseline pain/ quality of life. there were no significant differences found in outcome measures including recurrence rates, pain and quality of life outcomes at days, months, and year, surgical site infection (ssi), and postoperative length of stay (p[ . ). there was a significant increase in any post op complication in the permanent tack fixation group compared to the absorbable tack fixation group ( % vs %, p. ) which is likely due to the increase in surgical site occurrences noted in the permanent tack fixation group ( % vs. %, p. ). based on this large data set, there are no significant differences in postoperative outcomes in permanent versus absorbable fixation in laparoscopic hernia repair except in surgical site occurrences. further study is needed to evaluate but at the present time, there is no convincing evidence that one type of fixation is superior to another in laparoscopic ventral hernia repair. introduction: inguinal hernia repair is the most common procedure in general and visceral surgery worldwide. laparoscopic transabdominal preperitoneal mesh hernioplasty (tapp) has been also popular surgical method in japan. single incision laparoscopic surgery is one of the newest branches of advanced laparoscopy, and its indication has been spread to not only simple surgery such as cholecystectomy, but also complex surgery. we report our experience with single incision laparoscopic tapp (s-tapp) for japanese patients with inguinal hernia. case description: a consecutive series of patients ( male, female) who underwent s-tapp during june to september in a single institution. twenty eight of the patients had bilateral inguinal hernia. the mean follow-up was days. the average age of the patients was . ± . years. establishment of the ports: a -mm vertical intra-umbilical incision is made for port access. one -mm optical port and two -mm ports were placed side-by-side through the umbilical scar. surgical procedure: the procedure was carried out in the conventional fashion with a wide incision in the peritoneum to achieve broad and clear access to the preperitoneal space, and an appropriate placement of polypropylene mesh ( dmaxtm light, bard) with fixation using the tacking device (absorbatack®, covidien). the hernia sac is usually reduced by blunt dissection, or is ligated and transected with ultrasound activated device. the peritoneal flap is closed by one suture with - pds and the - tacks using absorbatack®. discussion: in one patient, we encountered a large sliding hernia on the right side having sigmoid colon as content of the sac, which required conversion to the conventional laparoscopic procedure. there were nine recurrence cases after surgery of laparoscopic or anterior approach, and two cases after prostatectomy. there was no intra-operative complication. the mean operative time was . ± . min, and blood loss was minimum in all cases. the average postoperative stay was . ± . days. there was one recurrence case ( . %) months after the surgery. there was no severe complication after the surgery, but there were seromas ( . %) and one hematoma ( . %). two patients had blunt tactile sense in the area of the lateral femoral cutaneous nerve ( . %), which improved in two months. conclusion: our results suggest that s-tapp is a safe and feasible method without additional risk. moreover, cosmetic benefit is clear. however, further evaluation for postoperative pain and longterm complications compared to standard laparoscopic tapp mesh hernioplasty should be required. manuel garcia, md, daniel srikureja, md, marcos j michelotti, md, facs; loma linda university health introduction: prosthetic mesh use has become standard practice during ventral hernia repair to reduce the risk of recurrence. the ideal mesh is macro-porous which favors rapid cellular ingrowth and tissue integration, has limited tissue reactivity, low profile and weight, and has high tensile strength to add resilience to the repair. additionally, the material is expected to have good handling characteristics. currently, there is a wide variety of options for mesh. biosynthetic material (poliglycolic acid/trimethylene carbonate -pga/tmc) has been shown to behave well in terms of early vascularization and ingrowth as well as adequate long term tissue generation. gore® synecor® biomaterial is a composite mesh including two layers of absorbable biosynthetic material (pga/tmc) with one tridimensional non-absorbable macro-porous knit of dense ptfe mesh. it has shown good vascularization and ingrowth at days in animal examination. however, there is still no evidence of long term behavior of this mesh in human tissue. we present the first histologic analysis of this mesh year after placement in a human. objective: to perform a histologic analysis of the gore® synecor® biomaterial one year after placement in the human body. methods: after incidentally finding incorporated gore® synecor® mesh in a patient with prior ventral hernia repair year ago, during open bilateral inguinal hernia repair, a sample of mesh was taken and sent to pathology lab for analysis. tissue healing, vascularization, and ingrowth of the composite mesh were analyzed. results: histologic findings significant for a biomaterial consistent with a knitted ptfe material surrounded by mature fibrovascular tissue and foreign body inflammation consistent with expected healing response for this time frame. no evidence of any other biomaterial (pga/tmc) or evidence of infection. conclusion: gore® synecor® biomaterial has shown to be well integrated into appropriately healed tissue, with pronounced vascularization and ingrowth. the pga/tmc layers have been seen to be completely absorbed and replaced by collagen. these findings, in a human months sample, replicate what had been shown in animal specimens. method: from to , patients came to hospital with renal paratransplant hernia. they were evaluated for this study. the following data were collected from their records: age, gender, weight, age at graft rejection, surgical complications, treatment method and the treatment results with composite ptfe mesh. results: for laparoscopic repair of incisional hernia after renal transplant, the median interval between kidney transplantation and developing of incisional hernia was (range to ) days. predisposing factors were obesity, age over fifty years, and female gender. in six patients, hernia was large, and the repair was performed with using composite ptfe mesh. one patient had developed serous collection in surgical site, which was managed successfully with multiple punctures. hernia recurrence or infection was not noted in these patients during to months follow-up periods. conclusion: incisional hernia is not a rare entity after kidney transplantation. predisposing factors, such as obesity, age over years, and female gender have a role in its development. repeated surgeries in kidney recipients can increase the risk of incisional hernia. managing this complication by laparoscopic approach is a safe and effective method. sujith wijerathne, raquel maia, hrishikesh salgaonkar, wee boon tan, lynette loo, davide lomanto; national university hospital, singapore introduction: a femoral hernia is a less common type of hernia. it is estimated to account for less than % of all abdominal wall hernias. only about in every groin hernias are femoral hernias. they are found more commonly in females due to wider shape of pelvis. laparoscopy by offering magnification and better vision provides us the opportunity for clear visualization of the myopectineal orifice. laparoscopy seems to be a safe and feasible approach for femoral hernia repair in an asian population. case description: between and , consecutive patients with femoral hernia who underwent laparoscopic hernia repair were prospectively studied. patient demographics, hernia characteristics, operating time, conversion rate, intraoperative, postoperative complications and recurrence were measured. discussion: total of femoral hernias were repaired, on right and on left groin. this included patients with bilateral and unilateral hernia. concomitant obturator hernia were found. there were male and female patient. no conversion was reported. one patient had injury to bowel at the mm port entry site, without contamination, identified and managed immediately. patients developed seroma, all were managed conservatively except one who needed aspiration. peri-port bruising was noticed in patients and patients had hematoma. one patient with hematoma underwent excision of the organised hematoma. of the hematoma patient was on aspirin pre-operatively. no wound infection, chronic groin pain or recurrence was documented during follow up till date. conclusion: laparoscopic repair offers accurate diagnosis and simultaneous treatment of both inguinal and femoral hernia with minimum morbidity and good clinical outcomes. better visualisation and magnification gives us an opportunity to identify occult hernias which can be repaired during the same setting, thereby reducing the chance of recurrence and possible need for second surgery. laparoscopic repair has become the procedure of choice for the treatment of the majority of groin hernia at our institution. introduction: totally extraperitoneal (tep) repair that does not require peritoneal incisions is a good procedure that involves minimal visceral damage. however, balloon-or camera-assisted blunt dissections that are performed in a haphazard manner do not follow precise dissection of the fascia layer. furthermore, they have a disadvantage in that they are difficult to understand anatomically. we therefore developed a novel preperitoneal approach to resolve this issue. methods: a -mm trocar is inserted into the rectus abdominis sheath cavity after a small incision is made below the umbilicus and the posterior rectus sheath is exposed. a -mm trocar is inserted cm towards the pubic bone from the umbilicus. using forceps from this position, narrow branches that enter the posterior rectus sheath from the inferior epigastric vessels are dissected, thereby broadly exposing the anterior surface of the posterior rectus sheath. the third mm-trocar is inserted near the lateral margin of the rectus abdominis. on the outside, local anesthetic is injected beneath the posterior rectus sheath and the preperitoneal cavity is separated in fluid so that the peritoneum is not injured during posterior rectus sheath incision. a small incision is made to the posterior rectus sheath or attenuated posterior rectus sheath at one finger width higher than the expected upper margin of the prosthetic mesh. due to the effects of local injection, a sharp incision to the fascia can be made with an electric scalpel. utilizing this mechanism, the posterior rectus sheath aponeurosis and the lining transverse fascia and superficial preperitoneal layer are individually identified. once the preperitoneal cavity is reached, the peritoneal margin is determined in the lateral direction, and the peritoneum that is pulled due to pneumoperitoneum is separated from the preperitoneal fascia on the outside from the cranial side towards the deep inguinal ring. on the inside, the pneumoperitoneum pressure pushes the peritoneum inferiorly, leading to enlargement and increased visibility of the posterior rectus sheath deep fascia, which is dissected one layer at a time from the outside. the umbilical prevesical fascia is dropped inferiorly, and the dissection of the preperitoneal cavity necessary for mesh deployment is performed. results: by individually dissecting each fascia using emphysema through pneumoperitoneum and enlargement through local injection, the method for reaching the preperitoneal cavity could be successfully completed by following the dissection of the fascia layer without proceeding with the operation blindly, thereby resulting in the elimination of intraoperative bleeding and postoperative hematoma. introduction: in the field of abdominal wall reconstruction, the utility of drain placement is of debatable value. we present outcomes evaluating drain placement vs no drain placement at the time of robotic transversus abdominis release (rtar) technique with placement of mesh in the retromuscular position, a currently understudied subject. methods: retrospective review of a prospectively maintained hernia patient database was conducted identifying individuals who received either drain placement or no drain placement during abdominal wall reconstruction via the rtar technique from august to june at a single high volume hernia center. perioperative data and postoperative outcomes between the two groups are presented with statistical analysis for comparison and quality of life (qol) measures assessed using the carolina comfort scale. results: thirty-five patients were identified for this study, of which had drains placed intraoperatively in the retromuscular position at the conclusion of rtar (drn) and underwent rtar without the placement of draining devices (nd). the drn cohort had a mean bmi, defect area, mesh area, and operative time of . , cm , cm and minutes, respectively, compared to . , cm , cm , and minutes in the nd group. all cases utilized medium weight macroporous polypropylene synthetic implantable mesh materials in both the drn and nd subgroups. there were no reported postoperative complications, including no development of hematoma, seroma, or surgical site infections in either group. hernia recurrence was not identified in either the drn or nd cohorts through a mean follow up of days ( . months). there were no statistically significant differences in postoperative qol outcomes. conclusion: our series review suggests that the use of intraoperative drains may not afford any benefits with the rtar technique when mesh is placed in the retromuscular position. additional postoperative management associated with drain care may be unnecessary. surg endosc ( ) :s -s background: appendectomy is one of the most common operations performed during emergency surgery. although laparoscopic appendectomy (la) has become the treatment of choice, there is still a debate regarding the use of la for treating complicated appendicitis. in this retrospective analysis, we aimed to clinically compare la and open appendectomy (oa) for treating complicated appendicitis. methods: we retrospectively identified patients who underwent an operation for complicated appendicitis at our hospital; these patients were operated on between and july . [editor ] in total, patients underwent conventional appendectomy and patients were laparoscopically treated. outcomes included operation time, blood loss, length of hospital stay, and postoperative complications. logistic regression analysis was performed to analyze the concurrent effects of various factors on the rate of postoperative complications. objective: small bowel perforation has conventionally been dealt with open exploration, which frequently leads to many wound-related complications. wound infection is the major reason for increasing morbidity in these patients and delay recovery. laparoscopic surgery has various benefits over open surgery like, smaller wound, lesser pain and faster recovery. the aim of this study was to relay the advantages of minimally invasive surgery (mis) to patients with small bowel perforation to decrease postoperative wound complications and duration of hospital stay. methods: it is a retrospective study, including patients with small bowel perforation from to . of these , had traumatic etiology, had typhoid-related perforation and the remaining had a duodenal perforation. of them were male, and the average age was . years. only patients who presented within hours of perforation were included in the study. laparoscopic exploration was done on introducing camera from -mm infraumbilical port after intraperitoneal carbon dioxide insufflation. the remaining two -mm working ports were then introduced depending on the site of perforation once identified. the perforations were then repaired using intracorporeal single-layer suturing using polydioxanone - suture. the peritoneal cavity was given thorough lavage and abdominal drain placed in the pouch of douglas. fecal contamination was found in all the patients. a total of patients underwent conversion to open surgery due to inability to find the site of perforation laparoscopically. of the operated patients, patients developed port-site infection, and there were no major postoperative complications in the -week follow up period. conclusion: we conclude from our study that laparoscopic intervention in early small bowel perforation is a safe approach with favorable outcomes, especially with regards to wound complications, that are a major factor in increasing the morbidity in such patients postoperatively. laparoscopic approach leads to early discharge and recovery postoperatively. with the emerging era of laparoscopic surgery, leading to its easy accessibility, more patients can advantage from this technique when they arrive in emergency with intestinal perforation. s surg endosc ( ) :s -s introduction: pneumatosis intestinalis (pi), or gas in the bowel wall, can be seen on various imaging modalities. the pathophysiology behind pi is unclear. one theory proposes a mechanical cause (e.g. small bowel obstruction) while another proposes a bacterial etiology. management of pi in adults is difficult as often there is a benign clinical course. however, when paired with specific clinical features such as hepatic portal venous gas (hpvg) on imaging, the course of management changes as the suspicion of bowel ischemia increases. hpvg alone has been associated with a high mortality rate and a poor prognosis. management in this case becomes surgical. case presentation: we present a case of -year-old latino male who presented to the emergency room with abdominal pain and altered mental status. focused physical examination revealed a non-rigid abdomen, no rebound tenderness, no guarding, and diffuse tenderness only to deep palpation. ct scan of the abdomen and pelvis demonstrated moderate portal venous gas in the right and left hepatic lobes, an upper midline dilated small bowel loop with pneumatosis intestinalis, and a moderately distended stomach with gas and fluid. laboratory studies revealed metabolic acidosis and a lactic acid level of . mmol/l. due to these findings, bowel ischemia was suspected, and the patient was taken to the operating room for a diagnostic laparoscopy. the laparoscopy was converted to an exploratory laparotomy due to extensive adhesions. intraoperatively, there was no small bowel compromise and no identifiable transition point. extensive lysis of adhesions and repair of iatrogenic enterotomy were performed. patient tolerated the procedure well, clinically improved, and was discharged from the hospital. discussion: this case illustrates the difficulty in management of a patient with pneumatosis intestinalis and, specifically, hepatic portal vein gas seen on ct imaging. hpvg has traditionally been a harbinger of morbidity and mortality, but exploratory laparotomy revealed only diffuse abdominal adhesions and the absence of bowel ischemia despite high clinical suspicion. background: ventral hernia repair is one of the most common surgical procedures facing the general surgeon. there is little consensus as to the best surgical technique for complex scenarios. often these patients have complicating co-morbid conditions such as radiation therapy, that has an inevitable effect in the abdominal wall structures, which can lead to non-traditional repairs. case report: we present a case of a year-old female who underwent a tah/bso and right hemicolectomy which was complicated by wound dehiscence. she underwent primary repair and adjuvant whole pelvis radiation for her squamous cell carcinoma. subsequently, the patient developed acute obstructive symptoms do to a stricture within her small bowel and a large ventral hernia measuring cm with non-reducible abdominal contents below the level of the fascia more prominent in the suprapubic area. the patient's bmi was . . various considerations are important in planning a surgical repair in a previously irradiated field with loss of domain which include, minimal dissection, and the use of an atraumatic surgical techniqueque with either external oblique release or transversus abdominis muscle release (tar). we chose a a tar, as it provides wider myofascial release and dissection below the arcuate line towards the space of retzius and bogros allowing for a larger sublay mesh placement. also it avoids the need of skin flaps reducing the risk for wound complications in under-perfused tissue. the tar was performed successfully and there were no intraoperative and postoperative complications. her follow-up at months revealed no wound complications or hernia recurrence. conclusion: for patients with compromised tissue and loss of domain a tar technique may be useful when reconstructing complex abdominal wall hernias. it provides the core principals of hernia repair such as primary fascial closure, wide mesh overlap, and finally it provides a reliable approach for the under-perfused tissue without need of skin and soft tissue flap creation. outcomes in the management of cholecystectomy patients in the setting of a new acute care surgery service model: impact on hospital course larsa al-omaishi, bs, william s richardson, md; ochsner medical clinic foundation introduction: the acute care surgery (acs) model, defined as a dedicated team of surgeons to address all emergency department, inpatient, and transfer consultations, is quickly evolving within hospitals across the united states due to demonstrated improved patient outcomes in the non-trauma setting. the traditional model of call scheduling consisted of one senior attending and one senior resident on call per -hour shift. attendings were responsible for consults, previously scheduled operations, as well as clinic time. multiple recent studies have shown statistically significant improvements in several parameters of patient care by using acs including but not limited to . time from emergency department to surgical evaluation . time from surgical evaluation to operating room . operative time . percent laparoscopic . length of hospital stay . intra-operative complications (blood loss, perforation rates) . post-operative complications (fever, infection, redo) . cost. one study demonstrated a statistically significant cost savings for the acute care surgery model with respect to appendectomies, but not cholecystectomies. study design: a retrospective analysis of patients who underwent cholecystectomy in the setting of non-traumatic emergent cholecystitis was performed to compare data from two cohorts: the traditional model and the acs between january , and dec , at ochsner medical center, a -bed acute care center in new orleans. parameters gathered included . time from emergency department to surgical evaluation . time from surgical evaluation to operating room . operative time . percent laparoscopic . length of hospital stay . intra-operative complications (blood loss, perforation rates, conversion to open) . post-operative complications (fever, infection, redo). demographics were also collected including age, weight, height, ethnicity, asa, etc. inclusion criteria included: age[ and having undergone cholecystectomy between jan , and december , . exclusion criteria included choledocholithiasis, gallstone pancreatitis, ascending cholangitis, gangrenous cholecystitis, septic complications precipitating further procedures and delays, or researcher discretion. results: patients were initially identified as having undergone cholecystectomy within the allotted time period [ - , - , - , - ] . were excluded due to one of the reasons above. median patient age was years old and the average patient encounter was . days. conclusion: the acs model is better suited to manage emergent non-traumatic cholecystectomies than the traditional call service at our institution, as evidenced by several parameters. s surg endosc ( ) :s -s he nailed it background: nail guns are powerful tools and are widely used. injuries with these devices may be devastating due to the significant force they can deploy. patients and methods: we herein report a first case of a self inflicted abdominal injury with a nail gun. results: a year old male with history of coronary artery disease, type dm and early signs of dementia attempted to refill a nail gun. he lodged the device against his right abdomen while the air hose was still attached and then accidently fired nails into his abdomen. after he unsuccessfully tried to pull the nails out he drove himself minutes to our emergency room. he was hemodynamically stable on arrival; pain control was achieved, antibiotics were given and he received tetanus immunization. ct-scan showed the two foreign bodies penetrating from the ruq with one reaching the transverse colon. on emergency laparoscopy, the nails were found to have penetrated the thick omentum and the puncture site of one nail into the colon was identified. the omentum was resected off the colon and the right colon was completely mobilized. no additional injuries were found. the entrance area of the nails was then used to create a loop colostomy. the postoperative course was initially uneventful but the patient developed a severe posttraumatic inflammatory reaction of the fat tissue in the right upper quadrant and had to be readmitted for pain control and antibiotics were again administered. he recovered and was discharged with a plan for laparoscopically assisted colostomy closure after weeks. discussion: to the best of our knowledge this is the first reported isolated colonic injury by a nail gun. given the tremendous force of the device with unknown collateral damage to the surrounding tissue it was decided to manage the accident with a laparoscopic assisted colostomy using the entrance point of the nails for fecal diversion. introduction: it is difficult to diagnose obturator hernias by routine physical examination. obturator hernias are frequently complicated by ileus and the diagnosis is often first made from abdominal ct. obturator hernias are difficult to reduce, and often necessitate emergency surgery. they are common in elderly people, and they often had bad general condition. so it was high in the death rate. at our hospital, we first attempt to reduce the hernia from the body surface under ultrasonographic guidance. after relieving the strangulation, we perform radical operation electively in patients who are for possible for surgery under the general anesthesia. we perform laparoscopic repair for obturator hernias. obturator hernias are often complicated by other types of hernia. in these cases, we perform total repair. herein, we present a review of the patients who underwent surgery for obturator hernia at our hospital. methods: we review the data of cases of obturator hernia encountered by us from february to december . we performed total repair in three of the cases. however, it is difficult to procure a mesh that would be adequate for all the defects (inner inguinal ring, femoral ring, obturator). no single mesh can fit, because the inguinal and pelvic curves present opposing curves near the obturator. therefore, we placed two pieces of mesh available at our hospital ( d max [bard] and onlay sheet of kugel patch [bard] ) together in the patientswe could successfully cover all the defects using these two pieces of mesh and could fit the mesh to the pelvic shape by devising an appropriate connection between the meshes. results: we reviewed a total of operated cases for obturator hernia. the hernia was bilateral in cases, and complicated by other hernias in cases. we first determined the appropriate approach for the repair. we performed total repair in cases. they were no complications and no cases of recurrence. conclusion: our approach to the repair of obturator hernias was very useful. we can use the exact area and shape of the mesh needed in individual patients by this method. we show the method of shaping the mesh to fit the pelvic form. demin aleksandr, do, ajit singh, do, noman khan, do; flushing hospital introduction: internal hernias are known complications that are well documented to involve peterson's defect. in bariatric patient's post gastric bypass there is a high index of suspicion for internal hernias as well as a low threshold to operate. there have been some debates around the closure of the potential peterson's space with several studies advocating closure versus some which show that there is no difference in the rate of symptomatic internal hernias. we present a case of an unusual cause of small bowel obstruction due to internal hernia caused by a cecal volvulus. it is an atypical presentation however the patient was triaged and brought to the or within hours of admission. although it is rare there have been reports of internal hernias caused by other structures like congenital bands or natural potential spaces. there have been reports of unusual presentations of the cecum herniating through the foramen of winslow. the anatomical rearrangements after bypass create potential areas where an internal hernia can occur. in this case a bowel resection was undertaken due to the anatomical variation of the cecal bascule and cecal volvulus due to high rate of recurrence of this cecal pathology. majority of internal hernias do not require bowel resection especially when detected earlier and prompt surgical exploration is undertaken. mortality as direct consequence internal hernia is extremely rare. however late diagnosis of internal hernias can lead to catastrophic gut loss and may require lifelong tpn and/or visceral transplantation or autologous reconstruction. conclusion: careful history and physical of our bariatric patient can elicit the signs and symptoms of internal hernias and prevent the morbidity and mortality that can come with the complications of this condition. unusual presentations and causes are reason for prompt diagnosis and complete exploration. shingo ishida , naotsugu yamashiro , satoshi taga , koichi yano ; shinkomonji hospital, shinmizumaki hospital symptomatic cholelithiasis is common disease performed with laparoscopic cholecystectomy (lc). we will hesitate to operate if the patient is pregnant in the third trimester. pregnant patients undergoing laparoscopic surgery have been reported increasingly. however, most case reports are confined to patients in the first and second trimester. we report a patient who underwent lc in the third trimester and review the relevant literature. a -year-old woman in the third trimester ( w d) of pregnancy was seen in the emergency department of our hospital with a history of upper abdominal pain. there was no problem in the course of pregnancy. the result of the examination proved to be attack of gallstone colic. she was hospitalized the same day and underwent lc the next day. the base of pregnancy uterus was cm above the navel. we needed to consider the surgical approach, for example inserting the first trocar under left hypochondrium. operative duration was minutes. she complained abdominal distension at postoperative day (pod) and but there was no abnormality in the fetus. she was discharged on pod . after that she gave birth to a healthy baby. lc in third trimester of pregnancy was safely performed with obstetrics back up. weekday or weekend hospital discharge: does it matter for acute care surgery? ibrahim albabtain , roaa alsuhaibani , sami almalki , hassan arishi , hatim alsulaim ; kamc, background: hospitals usually reduce staffing levels over weekend. this raises the question of whether patients discharged over a weekend may be inadequately prepared and possibly at higher risk for adverse events post-discharge. the aim of this study was to assess the outcomes of common acute care surgery procedures for patients discharged over weekend, and identify the key predictors of early readmission. methods: this retrospective cohort study was conducted at a tertiary care hospital between january and december . surgical procedures included were cholecystectomy, appendectomy, and hernia repairs. patients' demographic, co-morbidities, complications, readmission and follow-up details were collected from the electronic medical records. predictors and post-operative outcomes associated with weekend discharge were identified by multivariable analysis using univariable and multivariable logistic regression models controlling for potential confounders. results: a total of patients were included. overall median age was years (iqr: , ). the majority of patients were female (n= , . %). patients ( . %) underwent a cholecystectomy, ( . %) an appendectomy, and ( . %) hernia repairs. weekend discharge was . % vs. . % of weekday discharge. patients discharged during weekend were younger ( . vs. , p-value. , mean) . post-discharge -day follow-up visits were significantly lower in the weekend discharge subgroup ( . % vs. . %, p-value . ). overall, -day readmission rate was . % (n= ), and did not differ between those of weekend and weekday discharge (or= . , % ci . - . ). conclusions: patients discharged on weekends tended to be younger in age and less likely to have chronic diseases. patients discharged over the weekend were less likely to follow up compared to weekday discharge patients. however, the readmissions rate did not differ between the two groups. intrauterine device (iud) migration out of the uterine cavity is a serious complication. its incidence in the us has been reported to be about . % annually. previously published systematic review supports the use of laparoscopic surgery for elective removal of migrated iucds from the peritoneal cavity. we present the safety and efficacy of the laparoscopic approach to this complication in the acute care setting. depicted is an otherwise healthy year old female with no previous surgical history who presented to the ed with worsening abdominal pain for one week with no associated symptoms. on physical exam, patient was non toxic. abdomen was moderately distended with guarding and rebound tenderness to palpation, no rigid. patient had been seen shorlty prior to ed admission by her obgyn and recent work up with abdominal/pelvic x-ray and ultrasound has revealed a misplaced iud in the transverse position (side ways). pregnancy test was negative. based on patient clinical presentation and recent radiologic findings, we decided to proceed with diagnostic laparoscopy. after systematic review of cavity, the foreign body was found to be incorporated within the greater omentum. we procceded, laparoscopically with omentectomy+foreign body removal. there were no perioperative complications, patiet was discharged on the following day. the use of laparoscopy in elective iud retrieval within in the abdominal cavity has been considered standard of care in surgical management to date. this poster demonstrates its use as an effective approach for safe removal of intra-abdominal foreign bodies also in the acute setting. symptomatic inguinal and umbilical hernias in the emergency department: opportunity lost? andrew t bates, md, jie yang, phd, maria altieri, chencan zhu, bs, salvatore docimo, jr., do, konstantinos spaniolas, md, aurora pryor, md; stony brook university hospital introduction: patients with symptomatic inguinal and umbilical hernias often present to the emergency department (ed) when their symptoms change or increase, usually not requiring emergent surgery. however, little is known about how often these patients present prior to eventual repair and whether they undergo surgery at the initial presenting institution. the aim of this study was to assess the clinical flow of patients presenting in the ed for inguinal and umbilical hernia. methods: all patients presenting to eds in new york state from to with symptomatic inguinal and umbilical hernias were identified using the new york state longitudinal hospital claims database (sparcs). patients were followed for records of hernia repair and subsequent inpatient and outpatient visits up to . results: , patients presenting to the ed for symptomatic inguinal hernia were identified. . % ( , ) of ed presentations resulted in inpatient admissions. , ( . %) had repair later and their average time from ed presentation to inguinal hernia repair was (± ) days. . % of patients who did not have subsequent surgery had only one ed visit. of those that underwent interval repair, . % had only one ed visit prior to surgery. for those patients with only one ed visit before repair, . % had repair at a different hospital, as opposed to . % if multiple ed visits were made. , umbilical hernia patients presenting to the ed were identified. . % ( , ) resulted in inpatient admission. , ( . %) had interval repair, with the average time from ed presentation to umbilical hernia repair being (± . ) days. % of patients who did not record of later repair presented to the ed once. of those patients who underwent repair, . % did so after one ed visit. for those patients with only one ed visit before repair, . % had repair at a different hospital, as opposed to . % if multiple ed visits were made. conclusion: a majority of patients with symptomatic inguinal and umbilical hernias that present to the ed do so once with no subsequent follow-up or repair. for those patients that undergo interval repair, a significant portion willnopt for surgery at other hospitals. a significant proportion of patients with acutely symptomatic inguinal/umbilical hernias who undergo interval repair after a previous ed visit, will opt for definitive surgery at another hospital facility. this represents a missed opportunity for continuity of care for providers and healthcare systems. nikhil gupta, dr, himanshu agrawal, dr, arun k gupta, dr, dipankar naskar, dr, c k durga, dr; pgimer dr rml hospital, delhi introduction: peritonitis is the inflammation of the serous membrane that lines the abdominal cavity and the organ contained therein and is one of the most common infections, and an important problem that a surgeon has to face. reproducible scoring system that allows a surgeon to determine the severity of intra-abdominal infections are essential to prognosticate the patient. this study was done to compare apache ii scoring and mpi score to assess prognosis in perforation peritonitis. methods: all patients admitted with hollow viscus perforation from st november till st march was included in the study. it was a cross sectional observational study. apache ii and mannheim peritonitis index (mpi) scoring systems were calculated in all the patients in order to assess their individual risk of morbidity and mortality. the outcome variables were studied postoperatively -post-operative wound infection, wound dehiscence, anastomotic leak, respiratory complications, duration of hospital stay, need of ventilator support and mortality. the inferences were drawn with the use of appropriate tests of significance. results: the study comprised of patients. neither apache ii nor mpi could predict postoperative wound infection. the mean apache ii score of subjects included in the study was . ± . with range of to and the mean mpi score of subjects included in the study was . ± . with range of to . apache ii was able to predict postoperative respiratory complications, post-operative need for ventilatory support, hospital stay duration and mortality while mpi was able to predict post-operative wound dehiscence, post-operative respiratory complications, post-operative need for ventilatory support and mortality. neither apache ii nor mpi could predict postoperative anastomotic leak and postoperative wound infection. conclusion: mannheim peritonitis index is a useful and simple method to determine outcome in patients with peritonitis. mpi is comparable to apache ii in assessing the prognosis in perforation peritonitis and can well be used in emergency setting in place of apache ii scoring when time is a definite constraint. microrna- and the prognosis of human carcinomas: a systematic review and meta-analysis chengzhi huang, mengya yu; guangdong general hospital (guangdong academy of medical science) muhammad nadeem , julian ambrus, md , steven schwaitzberg, md , john butsch, md ; university at buffalo, introduction: mitochondria is a small energy producing structure of a cell. mitochondrial myopathy (mm) is mixed disorder clinically, which can affect various systems besides skeletal muscle. mm starts with muscle weakness or exercise weakness. mm patients have decreased skeletal muscle mitochondrial function than the healthy person, because of weakened intrinsic mitochondrial function and decreased mitochondrial volume density. no one has studied the mm role in gerd and constipation so far. this study is aimed to see effects of mm on the gastrointestinal system specifically gastroesophageal reflux disease (gerd), gall bladder issues, and constipation. methods: between may and june , mm diagnosed patients at buffalo general hospital were included in this retrospective study. we assessed their demeester score for gerd and wexner's constipation questionnaire for constipation. demeester score[ and constipation score[ were set points for gerd and constipation respectively. data was analyzed by using spss version . mitochondrial enzymes were assessed by using their muscle biopsy report. results: out of ( . % female, . % male) mitochondrial myopathy patients, . % and . % were suffering from gerd and constipation respectively. . %, . % and . % patients had gall bladder issues, obstructive sleep apnea (osa) and fatigue respectively. mm gerd patients ( . % female, . male) had mean demeester score . (sd: . ) more than normal although . % patients were on gerd medications and . % patients had nadh cytochrome c reductase, cytochrome c oxidase and citrate synthase abnormal mitochondrial enzyme in mm associated gerd but . % mm patients had abnormal cytochrome c oxidase enzyme only. mm along with constipation had mean wexner's constipation score . (sd: . ) more than the normal although . % were taking enema, medications or digital assistance. % patients had cytochrome c oxidase and nadh cytochrome c reductase enzymes were abnormal in those patients. . % mm associated gall bladder issues patients had cytochrome c oxidase abnormal. . % mm associated gerd and constipation patients had gall bladder issues. conclusion: in this present study, we found that mm had effects on gastrointestinal system causing gerd, constipation and gall bladder issues. gerd, constipation and gall bladder problems are common in mm patients even patients are taking medications for gerd and constipation. cytochrome c oxidase, citrate synthase and nadh cytochrome c reductase are the most commonly impaired mitochondrial enzyme in mm patients and mm associated gerd, constipation and gall bladder issues patients. objectives: gulf war illness (gwi) is a chronic, multisymptom illness marked by cognitive and mood dysfunction and disrupted neuroendocrine-immune homeostasis affecting % of gw veterans. after + years, useful treatments are lacking and its cause is poorly understood, although exposures to pyridostigmine bromide and pesticides are consistently identified among the strongest risk factors. previous work in our laboratory using an established rat model of gwi identified persistent elevation of microrna- (mir- ) levels in the hippocampus whose gene targets are involved in cognition-associated pathways and neuroendocrine function, suggesting that mir- inhibition is a promising therapeutic approach to improve the complex symptoms exhibited by gwi. the purpose of this study was to identify broad effects of mir- inhibition in the brain by profiling the expression of genes known to play a critical role in synaptic plasticity, glucocorticoid signaling, and neurogenesis in gwi rats administered a mir- antisense oligonucleotide (mir- inhibitor). methods and procedures: nine months after completion of a -day exposure regimen involving gw-relevant chemicals and stress, rats underwent intracerebroventricular infusion of mir- inhibitor (n= ) or scrambled negative control oligonucleotide (n= ) and were implanted with -day osmotic pumps delivering . nmol/day. intranasal delivery of oligonucleotides was performed on additional rats (n= per group; daily for days) to determine whether mir- inhibition is achievable using a noninvasive procedure. hippocampi were harvested and quantitative pcr arrays were used to profile the expression of focused panels of genes important for ) synaptic alterations during learning and memory, ) signaling initiated by the glucocorticoid receptor (known mir- target), and ) neurogenesis. hippocampi were also analyzed by quantitative pcr to examine expression levels of endogenous mir- . results: upregulation ([ . fold change, p. ) of synaptic plasticity genes, glucocorticoid signaling genes, and neurogenesis genes was observed in the hippocampus of gwi rats infused with mir- inhibitor compared to scrambled control, consistent with a significant reduction (p\ . ) in mir- levels detected in rats receiving mir- inhibitor. altered gene expression and a reduction in mir- levels were not observed in rats after intranasal delivery. conclusion: mir- antagonism in the hippocampus upregulates the expression of several downstream targets involved in synaptic plasticity, glucocorticoid signaling, and neurogenesis and is a promising therapeutic approach to improve cognition, emotion regulation, and neuroendocrine dysfunction in gwi. further testing is being pursued to discover the optimal dose for intranasal administration to test viability of this option for ill gw veterans. nikhil gupta, dr, ananya deori, dr, arun k gupta, dr, dipankar naskar, dr, c k durga, dr; pgimer dr rml hospital, delhi background: the ultrasonic dissector, commonly known as the harmonic scalpel, has been in use for achieving haemostasis in surgery for almost yrs. its advantages in breast surgery, especially in the dissection of axilla, have been a matter of debate as previous studies have shown inconsistent results. this study compares the outcomes of the ultrasonic dissector in axillary dissection with that of the conventional electrocautery. methods: patients who were undergoing mrm and bcs with axillary dissection from november till march were included in the study. patients were randomized into two groups, group a undergoing axillary dissection with ultrasonic dissector and group b with electrocautery. the operative time, intra-op bleeding, post-op pain, post op drain volume, hospital stay and any other complications were noted in the two groups. results: the numbers of patients in both groups were each. group a had a significantly shorter operative time, both for axillary dissection ( . min vs. . min, p. ) and the total duration ( . vs. . min, p= . ). the blood loss was significantly less in group a, as measured by the mop count. there was significant reduction in the total post-op drainage volume, which resulted in fewer days of drain in-situ and the total number days stayed in the hospital. there was no significant change in the post-op complications such as haematoma, seroma, flap necrosis, oedema, etc. conclusion: with the use of ultrasonic dissector, the operative time, blood loss and the axillary drainage was significantly reduced. the axillary drainage in turn, reduced the hospital stay. there was no significant difference in terms of complications like haematoma formation, seroma formation, skin flap necrosis or oedema. for the statistical analysis, χ or fisher's exact tests to compare proportions and the nonparametric mann-whitney u test for analysis of values with abnormal distribution were used. discussion: the study included patients. all preoperative laboratory indicators were elevated. the laboratory tests do not demonstrate any statistical significance between these two groups. the group of the patients without stones in the cbd diagnosed by ioc was also divided in patients with diameters. ?mm and with diameters≥ . ?mm of the cbd. also in these two groups, the statistical analysis of the laboratory tests does not demonstrate significant difference. all patients underwent ioc. ioc showed stones in / patients ( . %) . a comparison of patients with and without stones at ioc showed similar mean times from hospitalization to surgery ( . background: housed in a high volume tertiary referral center, our division receives a large amount of transfers and referrals from outside institutions for patients who require completion cholecystectomies. in this study "completion cholecystectomy" refers to patients that meet one of three criteria: . previous subtotal cholecystectomy, . previously aborted cholecystectomy, or . previous cholecystectomy with incidental finding of cancer on pathology. traditionally, exploration of a reoperative field in the right-upper quadrant mandates an open approach due to dense adhesions and inflammation. over the past few years, we have found that robotic-assisted surgery has allowed us to perform these completion cholecystectomies in a minimally invasive fashion. methods: case logs and operating room billing logs were reviewed from to to identify all robotic-assisted cholecystectomies performed at our institution. review of all reports identified completion cholecystectomies. all additional variables including demographics, operative variables, and postoperative outcomes were determined from manual chart review of all consultation notes, operative reports, anesthesia records, progress notes, discharge summaries, and postoperative office visits. results: of the identified robotic-assisted completion cholecystectomies, patients had a previous subtotal cholecystectomy, patients had an aborted cholecystectomy, and patients had an incidental finding of t gallbladder carcinoma on pathology. fifteen patients ( %) underwent preoperative ercp either for choledocolithiasis or to determine biliary anatomy. average time from original procedure was months with . % of previous procedures performed in an open approach. average or time was . minutes, average ebl was . cc, and average length of stay was . days. one patient ( . %) was readmitted within days for nausea that resolved with antiemetics. three patients ( . %) had minor postoperative complications (clavien-dindo grade or ) which resolved with pharmacologic therapy. no patients suffered a -day mortality. all cases were completed in minimally invasive fashion without a conversion to an open procedure. conclusions: although rare, completion cholecystectomies present a challenging surgical scenario. although traditionally performed in an open approach, we have had success in recent years at our institution with a robotic-assisted approach to completion cholecystectomy. we feel that the robotic approach offers certain advantages in a hostile, reoperative field which allows us to perform these procedures in a minimally invasive fashion with no conversions to an open procedure to date. previously limited to case reports, this report of procedures represents the largest case series of robot-assisted completion cholecystectomies to our knowledge. s surg endosc ( ) :s -s background: percutaneous cholecystostomy tube (pct) has been used as a bridge treatment for grade ii-iii moderate to severe acute cholecystitis (ac) to "cool" the gallbladder down over several weeks and allow the inflammation to resolve prior to performing interval cholecystectomy (ic) and removal of the pct, often laparoscopically. the aim of this study was to assess the impact of timing of ic after pct on operative success and outcomes. methods: a retrospective review of electronic medical records of patients who were treated for ac with a pct, and subsequently underwent ic at our institution between january to december was performed. the patients were divided into three groups (n= each), based on the duration of the pct prior to ic, and these groups were comparatively analyzed. a comparative sub-analysis of clinical outcomes between patients who underwent surgery within the first week vs. third week or later after pct was also performed. results: a total of patients met the study criteria. each group had patients. there were no statistically significant differences between the groups in regards to age, gender, bmi, imaging findings, and indications for cholecystostomy tube placement. overall, there was no statistically significant difference in outcomes between performing ic within the first weeks, - weeks and [ weeks after pct placement. the length of stay, overall morbidity, clavien-dindo grade of complications and mortality were similar between the time intervals. however, a sub-analysis showed that patients who underwent ic within the first week of pct placement had statistically significant higher mortality rate (p= . ) compared to those who underwent ic[ weeks of pct placement. the two patients who died in our sample had ic within a week after pct placement. even though there was a statistically significantly higher morbidity rate in those who had ic[ weeks after pct, the clavien-dindo grade of these complications was lower than. conclusion: delaying ic to [ weeks after pct placement for ac is not associated with any improvement in patient morbidity, length of stay or rate of conversion from laparoscopic to open cholecystectomy. cholecystectomy within the first week of pct placement is associated with higher mortality rate than after weeks likely due to associated sepsis. introduction: the effect of intraoperative bile spillage during laparoscopic cholecystectomy (lc) on operative time (or time), length of stay (los), postoperative complication rates, and day readmission rates was analyzed. laparoscopic cholecystectomy is the gold standard operation for gallbladder disease in the united states. number of studies have shown that same day discharge in elective laparoscopic cholecystectomy is feasible and safe. bile spillage during this procedure can be a common occurrence in teaching institutions, however, data on the effects of operative outcomes is lacking. methods: this is a retrospective study analyzing all of the laparoscopic cholecystectomies performed at the brooklyn hospital center (tbhc), both emergent and elective, from to . patient data was collected on demographics, comorbidities, bile spillage, operative findings, complications, los, and day readmission rates. statistical analysis was performed using imb spss statistics v. . covaried analysis of variance (ancova) was performed on continues variables and significance levels were calculated. pearson's chi square significance level was calculated for all binomial variables. results: of the patients who underwent lc during this time period, intraoperative bile spillage was encountered in patients. interestingly, bile spillage was significantly more likely to be seen in elective cases over acute cases ( . % vs . %, p. ). there was a statistically significant increase in or time in cases where intraoperative bile spillage was encountered vs. cases where no bile spillage was encountered ( vs. min, p= . ). there was a significant increase in rate of conversion to open procedure when bile spillage was encountered ( . % vs. . %, p. ). drain placement rates increased, not surprisingly, when bile spillage was encountered ( . % vs. . %, p. ). there was no statistically significant difference in los between cases with bile spillage and cases without ( . days vs. . days). there was no significant increase in complication rate or day readmission rates. conclusions: intraoperative bile spillage significantly increases or time, conversion to open procedure, and drain placement. however, there was no significant effect observed of intraoperative bile spillage on length of stay, complication, and day readmission rates. thus, intraoperative bile spillage appears to have little clinical significance on surgical outcomes. however it may have an impact on overall healthcare costs. larger prospective studies evaluating the effect of intraoperative bile spillage on los, or time, complication rates, and day readmission rates are needed to analyze these effects further. tariq nawaz, md; rawalpindi medical university study design: prospective and observational study. place and duration: from january, to july . surgical unit ll, holy family hospital, rawalpindi. patients and methods: thousand patients with a diagnosis of cholithiasis were included. exclusion criteria are patient younger than year and older than year. calot's triangle dissection was done meticulously. cystic artery and hepatic artery anomalies and variations were observed and analyzed on spss . results: the age varies from to years. on the basis of distributional variation the cystic artery was single in % cases, branched in % cases and absent in % cases. on positional variations the cystic artery was superomedial to the cystic duct in % cases, anterior in % cases, and posterior in % cases and low lying in % of the cases. on the basis of length variation results showed that ( %) cases had a normal cystic artery. a short cystic artery was found in ( %) cases and a long cystic artery was present in ( %) cases. other arterial variations are of hepatic artery i.e moynihan's hump ( %) and and right hepatic artery present in calots triangle in % conclusions: for the safety of laparoscopic cholecystectomy one should be well aware of the anatomical variations of the cystic and hepatic artery. keywords: cholelithiasis, cholecystitis, laparoscopic cholecystectomy. as small as it gets: micro-invasive laparoscopic cholecystectomy using only two mm trocars and a needle grasper background: the majority of surgeons use four ports including for laparoscopic cholecystectomy (lc). multiple efforts have been made to reduce number and size of ports. left upper quadrant (luq). patients and methods: of lcs performed from / - / , ( %) were done using three instruments including cases in which trocars and the teleflex needle grasper were used. in cases only two mm trocars were (left upper quadrant (luq) and umbilicus) with the minigrasper being placed between the two. the gallbladder (gb) serosa was incised on both sides and a window was created behind the gb midportion and widened towards fundus and infundibulum. cystic artery (ca) and cystic duct (cd) were dissected out obtaining the critical view and after the last fundus adhesion was cut, ca and cd were secured with clips or endoloop. results: median age of women and men was . (range . - . ) years. lc was done for acute cholecystitis (n= ), chronic cholecystitis (n= ), biliary dyskinesia (n= ), choledocholithiasis (n= ). three patients had an ercp with bile duct clearance prior to the lc. in one case a keith needle was used to suspend the gb fundus for better exposure. twelve patients had additional procedures together with their lc (wedge liver biopsy ( ), lysis of adhesions ( ) , umbilical hernia repair ( ) , mesenteric/lymphnode biopsies ( ) . median or time was (range - ) minutes. the specimen was removed through the luq port site in patients. there were no vascular or bile duct injuries in this series. % of cases were done as outpatient procedures, % of patients required hours observation only three patients were hospitalized for medical reasons. conclusion: in selected cases with either small stones or biliary dyskinesia, lc with only two mm ports and a needle grasper is possible. the teleflex minigrasper can completely replace a port based grasper. introduction: the standard treatment for lithiasic acute cholecystitis remains the laparoscopic cholecystectomy despite the timing of surgery is still controversial. the aim of this prospective study is to evaluate the advantages and limitations of early laparoscopic cholecystectomy in a district hospital. methods and procedure: all patients undergoing laparoscopic cholecystectomy at the surgical department of "carlo urbani" hospital in jesi (italy) from may to september were consecutively enrolled. clinical data such as gender, age, bmi, comorbidity, previous abdominal surgery, previous acute cholecystitis were collected. subsequently, the patients were arranged in two groups according to the timing of intervention (early versus elective surgery). for each group, we compared data concerning surgery, such as operative time, intraoperative and postoperative complications, length of hospital stay and cost analysis. results: this study is a part of an ongoing research. so far, we collected laparoscopic cholecystectomies. ten ( %) of them were admitted with acute cholecystitis and were operated during the hospital stay (group a). group b included patients scheduled for elective surgery (n= ; %). the two groups were comparable with respect to clinical data. conversion to open approach was performed in cases, all of them in group b. mean surgical time was . ± . minutes in group a and . ± . minutes in group b (p= . ). no significant differences in intraoperative and postoperative complications rates were seen in the two groups, just a few in both of them. mean overall length of hospitalization was . ± . days in group a and ± . days in group b (p= . ), whereas the difference in length of postoperative hospitalization was not statistically significant. due to the extended hospitalization for group a, the cost increase as compared to group b was statistically significant, too. conclusions: early laparoscopy is comparable to delayed laparoscopy in terms of postoperative hospitalization and complications in the management of acute cholecystitis. a longer hospital stay among patients scheduled for immediate surgery may be associated with a more time-consuming diagnostic work-up before surgery. however, in future research we expect to enhance our cost analysis with more data regarding the costs incurred in the first hospitalization reserved to nonoperative treatment of group b inpatients with acute cholecystitis. s surg endosc ( ) introduction: with improvements in healthcare access and technology, admissions of octogenarian population with acute cholangitis (ac) are increasing. octogenarians are vulnerable to inferior outcomes. there is no study to evaluate factors predicting outcomes of ac in octogenarians. the aim of our study is identify factors predicting outcomes, and to evaluate the quick sequential organ failure assessment (qsofa) score and tokyo guidelines (tg ) severity grading for octogenarian patients with ac. methods: a retrospective review of octogenarian patients admitted with ac from january to december was performed. demographic profile, clinical presentation and discharge outcomes were studied. systemic inflammatory response syndrome (sirs), qsofa and tg severity grading scores were calculated. mortality is defined as death within days of admission or in hospital mortality. statistical analysis was performed using spss version . results: there were a total of patients admitted for ac, of which ( %) were octogenarians. majority (n= , %) were female, with a mean age of (range - ) years. majority were secondary to gallstones (n= , %), and ( %) were due to malignancies. ( %) and ( %) patients fulfilled sirs and qsofa criteria of severity respectively. ( %) and ( %) of patients had a tg severity grading of moderate and severe respectively. nine ( %) patients required inotropic support in the emergency department (ed) and ( %) patients were admitted to critical care unit (ccu). ( %) patients underwent endoscopic retrograde cholangiopancreatography (ercp) and ( %) underwent percutaneous transhepatic biliary drainage (ptbd) for biliary decompression. patients underwent index cholecystectomy. length of stay was . (range - ) days and -day mortality of %. multivariate analysis performed showed that an abnormal glasgow coma score (p= . ) and malignancy (p. ) predicted -day mortality. the use of ed inotropic support predicted ccu admission (p= ). a positive blood culture (p= . ), presence of malignancy (p. ), use of ed inotropes (p= . ), and index cholecystectomy (p= . ) predicted a longer length of stay. qsofa (p. ) and tg severity grading (p= . ) were predictive of -day mortality. sirs criteria did not predict -day mortality. conclusion: reduced consciousness and malignancy predicted -day mortality in octogenarian patients with ac. qsofa and tg severity grading system is superior to sirs criteria in predicting mortality of octogenerians with ac. our group has performed needlescopic grasper assisted silc (nsilc) to overcome these problems. we evaluate the technical feasibility, safety and benefit of nsilc versus three-port laparoscopic cholecystectomy (tplc). methods and procedures: this prospective randomized control study was conducted to compare the advantages if any between the nsilc and tplc. one hundred and forty eight patient were randomized into two groups, with one group underwent n slic ( patients) and a control group underwent tplc ( patients). basic information about the patient and diagnosis was collected. the surgical outcome that was composed with critical view of safety (cvs) time, major procedure time and total operation time, and the comparison of postoperative complication was made. result: nsilc group was consisted of male ( . %) and female ( . %), and tplc group was consisted of male ( . %) and female ( . %) (p= . ). the average age of nsilc group was . ± . years old, and tplc group was . ± . years old (p= . ). cvs time of tplc group was shorter than silc group (nsilc: . ± . min, tplc: . ± . min, p= . ), major procedure time (skin incision to gb removal from liver bed) of tplc group was shorter than nsilc group (silc group: . ± . min, tplc: . ± . min, p= . ). however, there was no significant difference in postoperative complication (nsilc: , tlc: , p= . ). conclusion: although cvs time, major procedure time, and operation time of silc were longer than tplc, overall clinical results were similar. nsilc is feasible and safe surgical procedure in patient with benign gallbladder disease. introduction: management of malignant biliary obstruction not amenable to surgery is usually by means of ercp or pthc. however, on occasions, these routes are not accessible and the alternate decompressive technique of percutaneous cholecystostomy (pc) has to be adopted. the aim of this study was to evaluate the efficacy and outcomes of pc in a highly selected series at a tertiary referral center. methods: we retrospectively reviewed all patients that had undergone pc from to . data collected included baseline demographics, comorbidities, details of pc placement and management, etiology of mbo, and post-procedure outcomes. the charlson comorbidity index (cci) was calculated for all patients at the time of pc. results: four hundred and eight patients underwent pc placement of which patients including ( %) males and ( %) females, with malignant biliary obstruction. the mean age at the time of pc placement was . ± . years of age, and the mean cci was . ± . for all patients. of mbo in all patients was due to pancreatic malignancies (n= ), cholangiocarcinoma (n= ), primary hepatic malignancies (n= ), secondary hepatic tumors (n= ), and ampullary carcinoma (n= ). pc tube complications were reported in ( %) patients. mean number of tube exchanges was . ± . . mean duration from pc tube placement to death was ± . days. total deaths were recorded. conclusion: pc placement appears to be a viable option in mbo in elderly and frail patients. in this cohort, pc may be a potential definitive management to improve quality of life. melanie boyle, daivyd palencia, philip leggett; houston northwest medical center background: there are very few studies assessing the relationship between gastroesophageal reflux and biliary disease. this is surprising as they share presenting symptoms as well as risk factors, particularly obesity. our group previously produced a review of patients in our practice who had undergone some type of reflux procedure. conclusions showed that the prevalence of gallbladder disease in our severe reflux population is much higher compared to that found in the general population. our goal of this study is to expand on that data to include a larger sample size to investigate the incidence of biliary disease in our reflux population and decide if this should influence our pre-operative algorithm for anti-reflux surgery patients. methods: we expanded on our previously performed retrospective review of patients that underwent laparoscopic fundoplication for reflux disease. we previously reviewed data from to . we are now looking at data from to . our expected sample size will include approximately patients, of which have currently been reviewed. our previous study included only . the surgery preformed was either a toupet or nissen fundoplication, and one underwent a dor. demographic data, imaging studies, and pathology results were reviewed. results: we looked at whether each patient who underwent antireflux surgery had a prior cholecystectomy either remotely or recently, underwent concomitant cholecystectomy, or had no biliary disease in their workup. the groups had similar age and were predominantly women. we once again demonstrated that the prevalence of gallbladder disease in our severe reflux population is much higher than the general population. when approaching a patient with gastroesophageal reflux disease, attention should be paid to gallbladder symptomatology as well. we recommend that it may be beneficial to include gallbladder ultrasound in pre-operative workup for antireflux surgery so that concomitant cholecystectomy can be performed if indicated. steven schulberg, do, jonathan gumer, do, matt goldstein, vadim meytes, do, george ferzli, md; nyu langone hospital -brooklyn introduction: acute cholecystitis is a common surgical disease with roughly , cholecystectomies performed in the us annually. the current dogma revolves around the " hour rule" advocating early cholecystectomy if within the window, and if beyond hours, conservative treatment and interval operation. in patients beyond the hour window, as well as with multiple comorbidities, advanced age, and other complicating factors, cholecystostomy has become an acceptable treatment as a bridge to interval cholecystectomy. while this has become an appropriate treatment modality, it does not come without its own set of complications. we aim to evaluate the rate of complications in our institution. methods: this is a retrospective review of all patients at our institution who underwent cholecystostomy placement between and . we evaluate the comorbidities, readmission rate, overall rate of complication associated with cholecystostomy tubes, and eventual definitive cholecystectomy. results: our cohort includes patients, % of whom were male, with a mean age of . we had an overall complication rate of . %, including tube dislodgements, leaking tubes, and misplaced tubes. all cause readmission rate was % and only % of patients who had cholecystostomy drains underwent interval cholecystectomy. conclusion: there has been much interest in treatment of acute cholecystitis in patients with multiple comorbidities. in review of our data, a surprisingly large number of patients had mechanical complications involving the cholecystostomy drain. in an era focused on decreasing readmission rates and their associated costs, drains carry a high risk of malfunction which will in turn, lead to increases in these two metrics. while there is more work to be done in the evaluation of early cholecystectomy versus cholecystostomy in this subgroup of patients, we suspect that early cholecystectomy in the medically optimized patient will lead to reduced length of stay and hospital costs as well as increased patient satisfaction. does selective use of hepatobiliary scintigraphy (hida) scan for diagnosis of acute cholecystitis, following equivocal nondiagnostic gallbladder ultrasonography, affect outcomes fahad ali, ba, amir aryaie, md, eneko larumbe, phd, mark williams, md, edwin onkendi, md; texas tech university health sciences center introduction: acute cholecystitis (ac) is diagnosed by characteristic gallbladder ultrasonographic findings (high specificity, low sensitivity). hepatobiliary scintigraphy (hida) may be needed to confirm ac (higher sensitivity and specificity). the aim of this study was to assess the impact of the current selective use of hida scan for sonographically equivocal cases of ac on outcomes. methods: a retrospective chart review of patients treated for ac at our institution ( / to / ) was performed. patients were divided into groups: the ultrasound only group (us-only) and the ultrasound-hida group (us-hida). timing of us and hida, and intervention for ac since presentation to emergency room (er), and their impact on outcomes were analyzed. ac severity was graded per the tg -tokyo guidelines. results: a total of patients were analyzed. the groups were statistically similar with regards to age, body mass index, asa class ii, iii and iv, extent of leukocytosis at presentation and liver functions test levels at presentation. in the us-only group, diagnostic ultrasound was obtained sooner, [median of (interquartile range, iqr . - . ) hours] from presentation to the er compared to the us-hida group, ) hours], p= . . hida was obtained after a median delay of . (iqr . - ) hours from a nondiagnostic ultrasound. majority of patients ( %) in the us-only group had mild (tg grade i) to moderate (tg grade ii) ac, while % of the us-hida group had moderate (tg grade ii) to severe (tg grade iii) ac (p= . ). despite this, more patients in the us-hida group ( %) had a "normal" non-diagnostic ultrasound compared to the us-only group ( . %), p. . seven patients in the us-hida group had no intervention due to normal hida scan ( ) , ac misdiagnosis due to liver cirrhosis ( ) , and severe medical comorbidities ( ) . more patients ( %) in the us-only group underwent laparoscopic cholecystectomy, compared to % in the us-hida group (p= . ). between the two groups, there was no significant differences in -day morbidity, mortality and reoperations. however, the length of stay was longer by a median of . days in the us-hida group (p= . ). conclusion: patients with moderate to severe ac are more likely to need hida scan due to a "normal" non-diagnostic ultrasound, have a delay in diagnosis, not have intervention for ac due to severe medical comorbidities and have lower chance of laparoscopic cholecystectomy. the length of hospital stay is significantly longer for these patient by a median of . days. introduction: benign gallbladder disease is commonly treated with laparoscopic cholecystectomy (lc). gallbladder cancer (gbc) is a rare malignancy characterized by high invasiveness and poor survival. in our institution, all gallbladder specimens are routinely sent to pathology, to rule out gbc. the purpose of our study was to assess the efficacy for routine histopathology of gallbladder specimens after cholecystectomy (cly) for all gallbladder disease. methods and procedures: after obtaining approval from our institutional review board, a retrospective review was conducted on all patients who underwent cly from june of to may were included in the study. the data obtained include gender, age, american society of anesthesiologist score (asa), body mass index (bmi), comorbidities, length of stay (los), radiological imaging and pathology results. independent t and chi-square tests were performed using ibm® spss® software. results: there were cly performed at our institution, of which ( %) were lc. females composed of ( %) patients and the median age was . ( %) gallbladder specimens were found to be cancerous. ( %) gallbladder specimens were benign. majority ( %) were chronic cholecystitis, ( %) were acute cholecystitis and ( %) were gangrenous cholecystitis. ( %) were found to be acalculus cholecystitis and ( %) were cholelithiasis. ( %) were found to be adenomyositis, and other. conclusion: in our institution, less than % ( ) of all gallbladder specimens were found to be cancerous. it would decrease cost and work load if gallbladder specimens are selectively sent to pathology. emanuel a shapera, md we sought to determine clinical factors associated with recurrent cholangitis in two las vegas community hospitals to aid providers in management of this disease. methods and procedures: retrospective, multi-center study. over ercps were analyzed between and . patients were identified as having multiple ( ) admissions for cholangitis per tokyo criteria. univariate and multivariate analysis was conducted. results: patients with a significantly (p. ) higher albumin level on admission ( . ) were discharged home more often than patients discharged to a facility or hospice ( . ). on multivariate analysis, non-home discharge was associated with lower albumin level at admission (p= . ) and greater maximum temperature prior to decompression (p= . ). increased hospital stay was associated with lower albumin level at admission (p= . ). a majority ( / ) of recurrent episodes involved stent placement, exchange or removal. patients ( %) had either biliary malignancy, gallbladder or both. blood cultures were drawn in % of all episodes and positive in %, e coli being the most common pathogen isolated. all patients had low hdl levels ( - , mean ) . conclusions: high fevers and poor nutritional status was associated with increased length of hospital stay and fewer home discharges. tumors, gallbladders and malfunctioning stents contribute substantially to morbidity. close follow up for indicated gallbladder removal, stent management and nutritional optimization is critical to reduce the burden of this disease. we compared the surgical method in neonate choledochal cyst between oec and lec. the perioperative and surgical outcomes that were reviewed included age, operative time, postoperative hospital stay, time to diet, and surgical complications. the patients were followed up for months (range, - months) . results: there was no difference in range of bile duct excision and manner of roux-en-y hepaticojejunostomy between oec and lec groups. there was no intraoperative complication in both groups and no open conversion in the lec group except one case which was ruptured choledochal cyst. the median age of oec and lec groups were days (range, - ) and . days (range, and median body weight at the time of operation were . kg (range, . - . ) and . kg (range, . - . ) , respectively. the median operative time was minutes (range, - ) in oec and . minutes (range, in lec groups and there was no significant difference between oec and lec groups (p= . ). intraoperative bleeding was minimal in both groups. the postoperative hospital-stay, time to start diet, and time to return to full feeding had no significant differences in both groups. after discharge, of ( %) oec patients experienced readmission due to cholangitis and ileus, while there were none in the lec group. conclusions: this study revealed that lec had better prognosis compared to oec. lec provided an excellent cosmetic result. so we suggest lec could be the treatment of choice for neonatal choledochal cyst. this is a small series, therefore future studies will have to include a larger number of patients and evaluate long-term follow-up. keywords: choledochal cyst, laparoscopy, neonate. laparoscopic narrow band imaging for intraoperative diagnosis of tumor invasiveness in gallbladder carcinoma: a preliminary study yukio iwashita, hiroki uchida, teijiro hirashita, yuichi endo, kazuhiro tada, kunihiro saga, hiroomi takayama, masayuki ohta, masafumi inomata; oita university faculty of medicine introduction: determining tumor invasiveness before operation is one of the most important unsolved issues in the management of gallbladder cancer. we hypothesized that the assessment of irregular vessels on the gallbladder wall may be useful for detecting subserosal infiltration. we present an initial report on the clinical usefulness of laparoscopic narrow band imaging (nbi) for the intraoperative diagnosis of tumor invasiveness in gallbladder carcinoma. methods: thirteen patients with gallbladder cancer were included in this study. patients with tumors located in the liver bed and those with definitive invasion observed on computed tomography findings were excluded from this study. gallbladders were observed using nbi and the microvasculature was evaluated. according to previous reports of endoscopic nbi, we defined four findings as positive: vessel dilatation, tortuousness, interruption, and heterogeneity. the nbi findings were compared with postoperative pathological findings. the study protocol was approved by the institutional review board of the oita university. results: the serosal surface of the tumor site and its microvasculature were successfully observed in all patients. laparoscopic nbi detected at least one abnormal finding in seven patients, and postoperative pathology showed subserosal infiltration accompanied by vessel invasion. on the contrary, six patients with no positive nbi findings showed mild or no subserosal infiltration and no vessel invasion. conclusions: our study indicated that laparoscopic nbi may be useful for diagnosing subserosal infiltration accompanied by a vessel invasion. shuichi iwahashi, mitsuo shimada, satoru imura, yuji morine, tetsuya ikemoto, yu saito, hiroki teraoku; department of surgery, tokushima university introduction: laparoscopic cholecystectomy (lap-c) is the standard operation for the benign diseases. we have reported reduced port lap-c (rpl-c) was safely and comparable method to sils-c and conventional lap-c (sages ) . in this time, we examined the utility of rpl-c containing the post-operative adverse event. procedures: the adjustment is the benign illness including the cholecystolithiasis, and advanced obesity and the cases of the inflammation remaining have been excluded. the incision is put and cut open the abdomen to the umbilical region, and camera port was inserted. we used mm flexible scope. mm forceps for holding of the gallbladder bottom and left hand of operator were inserted directly with no port. methods: rpl-c has been introduced in this department since july, . we performed cases of lap-c, containing sils-c and american style conventional lap-c, and we performed rpl-c has been performed already cases. we compared the patient background and the operation factor between rpl-c, sils-c, conventional lap-c. operators were young surgeons, they were not specialists of gastroenterological surgery or endoscopic surgery. results: the difference was not admitted in the age, gender, the physique, and the disease, and the difference was not admitted in hospital stay after the operation (rpl-c:sils-c:conventional lap-c= . ± . days: . ± . days: . ± . days) and the amount of blood loss (rpl-c:sils-c:conventional lap-c= . ± . ml: . ± . ml: . ± . ml) and operation time (rpl-c:sils-c:conventional lap-c= ± min: ± min: ± min). and surgical wound after rpl-c was cosmetically acceptable. regarding as the post-operative adverse event, there were no patients of bile duct injury. conclusion: in the patients on reduced port lap-c, there were no bile duct injuries of postoperative adverse event. reduced port lap-c is safely for young surgeons and comparable method. introduction: acute cholangitis is an ascending infection of the biliary tree secondary to obstruction and can be severe if proper intervention and treatment are not performed in a timely fashion. the most common management of cholangitis with ductal obstruction due to choledocholithiasis is intravenous hydration, empiric antibiotic therapy, endoscopic retrograde cholangiopancreatogram (ercp) with sphincterotomy and stone extraction with or without stent placement, followed by a delayed laparoscopic cholecystectomy. we present the case of a patient with blood clot obstruction of a common bile duct (cbd) stent after ercp with sphincterotomy and stone extraction. case presentation: a year old male presented to the emergency department with jaundice, right upper quadrant abdominal pain, truncal pruritis, nausea, vomiting, and fever. biochemical analyses and liver profile demonstrated an elevated white blood cell count, hyperbilirubinemia, and elevated liver enzymes consistent with cholestasis. biliary ultrasound demonstrated multiple gallstones and dilation of the cbd with a distal obstructing calculus. he proceeded to ercp where biliary cannulation was achieved, sphincterotomy performed, and a large amount of sludge and pus was drained. an mm stone was removed from the cbd by balloon sweep with completion cholangiogram demonstrating no filling defects. a stent was then placed in the cbd with adequate flow. following the procedure, the patient continued to have increasing hyperbilirubinemia. a repeat ercp revealed a large blood clot and continued bleeding at the previous sphincterotomy that resolved with epinephrine injection. the former stent was visualized in the proper position, removed with a snare, and found to be fully occluded with blood clots. after retrieval of additional clots, a new stent was placed with adequate return of bile. the patient recovered with resolution of his symptoms and hyperbilirubinemia with laparoscopic cholecystectomy. discussion: cholangitis is characterized by charcot's triad of right upper quadrant abdominal pain, fever, and jaundice due to an ascending bacterial infection of the biliary tree coinciding with obstruction of biliary flow most commonly from gallstones. cholangiography via ercp with associated sphincterotomy, stone extraction, and stenting is both diagnostic and therapeutic. while debated by endoscopists, stent placement has shown to reduce recurrent biliary complications, decrease length of hospital stay, and lessen morbidity. although pancreatitis is the most common cause of hyperbilirubinemia post-ercp, stent occlusion secondary to stones or blood clots should be considered to effectively treat patients. proper hemostasis is important in any procedure and close patient follow-up should be performed to prevent further complications. sarrath sutthipong, md, panot yimcharoen, md, poschong suesat, md; bhumibol adulyadej hospital background: choledochal cyst (cc) is a rare disease, characterized by dilatations of the extra-or/ and intrahepatic bile ducts. ccs occur most frequently in asian and female populations. cc is associated with biliary lithiasis and considered at risk of malignant transformation. todani's classification dividing cc into types is the most useful in clinical practice. the current standard treatment is complete cyst excision with roux-en-y hepaticojejunostomy and cholecystectomy for the extrahepatic disease (todani type i and iv). in this report we present our experience using a total laparoscopic technique to treat adult patients with cc in -year period. methods: a retrospective review of the records of the patients above years who underwent laparoscopic cyst excision and roux-en-y hepaticojejunostomy in our hospital between january and may was carried out. the data included the clinical presentation, investigation, perioperative details and complication. the type of cc was classified according to todani's classification. results: seven cases of cc were reviewed, females and male with mean age years (range - years). these included cases of todani type ib and cases of type a. the predominant symptoms were chronic abdominal pain and jaundice. a case of both pancreatitis and cholangitis were also seen. investigations included ultrasound with mrcp in cases and ercp in case. the mean operative time was hours and minutes ( hours minutes to hours range) with mean intraoperative blood loss ml (range - ml). all the resected specimens showed chronic inflammation. malignancy was not seen in any patients. the early postoperative complications included bile leakage with intra-abdominal collection in patients, which were managed conservatively (evidenced by clinical status and imaging study), re-operation was not required. the median duration of hospital stay was days (range - days). there was no perioperative mortality. all patients were followed up at , , and months postoperatively, late complication were not detected during each visit. conclusion: in our opinion, laparoscopic cyst excision and hepaticojejunostomy could offer more feasible and safe methods of treatment for ccs in adult patients with potentially less postoperative morbidity, a shortened length of stay and a lower blood loss when compared to the preferred open approach. however, we would need to study this on a larger sample of patients to report the efficacy and safety of laparoscopic approach. endoscopic trans-papillary gallbladder drainage (etgbd) in acute cholecystitis: a single center experience arun kritsanasakul, chotirot angkurawaranon, jerasak wannapraset, thawee rattanachu-ek, kannikar laohavichitra; rajavithi hospital background: surgery is the mainstay of treatment for cholecystitis, however, it may not be safe or feasible in some circumstances such as severe cholecystitis or cholecystitis in extremely high-risk patients. gallbladder drainage may be an appropriate alternative or a bridging option prior to cholecystectomy. endoscopic trans-papillary gallbladder drainage (etgbd) has been proposed as a modality that is feasible and effective in cholecystitis. objective: the primary outcome of this study is to evaluate the effectiveness of etgbd. the secondary outcome is to evaluate the safety, early experience outcomes, and complications of this procedure. methods: retrospective medical records review between january -december from a single tertiary referral hospital center, rajavithi hospital, bangkok, thailand. a total of patients who was diagnosed with cholecystitis and underwent etgbd. the procedure was performed at the endoscopic suite under light sedation via total intravenous anesthesia. the patient demographic data and procedures were collected. the technical success of etgbd was defined as decompression of the gallbladder by successful cystic duct stent placement. the clinical success was defined as resolution of symptoms and/or improved laboratory data or ultra-sonographic findings. results: a total of patients underwent etgbd. among these patients, were high risk for surgery due to age or comorbidity, had concomitant jaundice and was failure of medical treatment. both technical and clinical success of etgbd was achieved in of cases ( %). the two patients that did not achieve technical success were due to failure to cannulate guidewire through cystic duct and the other had trans-cystic guidewire perforation that needed surgical intervention. there were two intra-operative complications ( %). one was the patient who had trans-cystic guidewire perforation and another had anesthesia-related complication (hypoventilation requiring endotracheal intubation). there were no -day mortality. conclusion: endoscopic trans-papillary gallbladder drainage is an alternative treatment modality for patients with cholecystitis who are at high-risk for surgery and or those who are unsuitable for percutaneous gallbladder drainage. the technique is feasible, however, careful case selection and high endoscopic skill is needed. julia f kohn, bs , alexander trenk, md , woody denham, md , john linn, md , stephen haggerty, md , ray joehl, md , michael ujiki, md ; university of illinois at chicago; northshore university healthsystem, northshore university healthsystem introduction: subtotal cholecystectomy, where the infundibulum of the gallbladder is transected to avoid dissecting within a heavily inflamed triangle of calot, has been suggested as a method to conclude laparoscopic cholecystectomy while avoiding common bile duct injury. however, some case reports have suggested the possibility of recurrent symptoms from the remnant gallbladder. this retrospective case series reports a minimum of two-year follow-up on patients who underwent subtotal cholecystectomy within one four-hospital system. methods: a retrospective chart review database containing randomly selected cholecystectomies, all of which occurred between and , was reviewed to identify all instances of subtotal cholecystectomy. charts for these patients were reviewed through / , including any documentation from other providers, including primary care. results: six patients who underwent subtotal cholecystectomy with a remnant of infundibulum left following surgery were identified. surgical approach and the choice to perform subtotal cholecystectomy were dependent on the attending surgeon; all decisions were made intraoperatively. there was an average of months of follow-up for these patients within our institution. discussion: this case series adds six cases to the literature surrounding long-term outcomes in patients who underwent subtotal cholecystectomy. although one patient was lost to follow-up, no patient had recurrent biliary colic or other complications arising from the remnant gallbladder. this may be encouraging to surgeons who feel that subtotal cholecystectomy with an infundibular remnant is the safest way to proceed with cholecystectomy in patients with severe inflammation. objective: this study aims to evaluate the utility and efficiency of icg as an alternative to routine intraoperative cholangiogram in patients undergoing cholecystectomy. introduction: common bile duct injury is an uncommon, but serious complication associated with laparoscopic cholecystectomy. current guidelines state that when used routinely intraoperative cholangiogram (ioc) can decrease biliary injury, however it is not routinely used due to increased time of operation, and inaccessibility of equipment. indocyanine green (icg) has been found to be effective for identification of biliary anatomy during cholecystectomy, however has not yet been widely adopted. we aim to assess if icg is able to overcome the obstacles of ioc, while still effectively assessing biliary anatomy. methods: we performed a retrospective analysis of laparoscopic cholecystectomies performed in a single institution from january to september . elective and emergent cases were included. we stratified patients into icg and non-icg groups. patients who had concomitant procedures performed were excluded. we analyzed patient demographic information, as well as bmi, asa classification and comorbidities in both groups. our primary outcome was operation time (skin to skin), and laparotomy conversion rate. secondary outcomes were effectiveness of icg in visualizing biliary anatomy, and cost. results: patients were included in our study, in the non-icg arm and in the icg arm. both groups were similar in background. there were no statistical differences in patient demographics, asa classification, bmi, or comorbidities. there was no statistical difference in operation time ( . vs . minutes; p. ) or conversion rate ( . vs %; p. ). icg was able to delineate biliary anatomy in % of the patients. the cost of a mg/vial kit of icg is approximately $ . conclusion: the use of icg does not increase operating time during laparoscopic cholecystectomy. icg is an inexpensive and effective tool used to delineate biliary anatomy without the inherent burden and limitations of ioc. benefsha mohammad, md , michele richard, md , steve brandwein, md , keith zuccala, md ; danbury hospital, danbury hospital department of gastroenterology, introduction: obesity is a prevalent issue in today's society, which has increased the number of gastric weight loss surgeries. this presents an anatomical challenge to biliary disease requiring endoscopic retrograde cholangiopancreatography (ercp). in gastric bypass patients, traditional ercp via the mouth in these patients is technically more challenging, requiring a longer endoscope with a reported success rate of less than %. a solution is laparoscopic assisted ercp (la-ercp) via gastrostomy. this minimally invasive technique has become increasingly more prevalent and safe. we present our experience with la-ercp at our teaching community hospital in a large cohort of patients. methods and procedures: retrospective chart review was performed on all patients with a history of prior laparoscopic gastric bypass surgery who underwent la-ercp from april to april . the procedure was performed by two different general surgeons and one gastroenterologist. a pursestring suture and transfacial stay sutures were used to bring the gastric remnant to the abdominal wall. a gastrostomy was then created and accessed by the duodenoscope to perform the ercp. biliary sphincterotomy, papillary or biliary dilation, lithotripsy, stent placement, and/or stone removal were performed as indicated. we observed the incidence of postoperative outcomes, including acute pancreatitis, reoperation, post-procedure infection, pain control, hospital re-admission and bile leak. results: thirty-two patients met inclusion criteria. six patients were male and twenty-six were female, with mean ages of (std dev ) and years (std dev ), respectively. indications for la-ercp included suspected choledocholithiasis ( / ), cholangitis with choledocholithiasis ( / ), acute pancreatitis ( / ), abdominal pain with abnormal lft ( / ), cholangitis with cholecystitis ( / ), and bile leak ( / ). la-ercp was successfully performed in all thirty-two patients. biliary cannulation, sphincterotomy and stone extraction were performed on / patients, and one patient underwent sphincterotomy and stent placement for bile leak after recent laparoscopic cholecystectomy. one patient developed acute pancreatitis with elevated pancreatic enzymes which resolved after conservative treatment. one patient required a second la-ercp for stent replacement due to a persistent bile leak. the median length of stay was days (range - days). conclusions: la-ercp is a safe and feasible alternative to open surgery, and can be safely implemented at community hospitals with adequately trained providers. obesity is a growing burden on society, increasing the incidence of weight loss surgery. our large study proves that in this minimally invasive era, la-ercp provides gastric bypass patients a safe alternative with less pain and increased satisfaction. ahmed elgeidie, elsayed adel; gastrointestinal surgery center background: endoscopic sphincterotomy (es) is an effective therapeutic procedure for common bile duct (cbd) stone clearance but it carries a substantial risk of recurrent stones at long-term outcome. aim of the study: to evaluate the rate of cbd stones recurrence after primary complete endoscopic clearance, and to identify the risk factors of recurrence. methods: between january and december , patients with cbd stones who underwent successful es and complete stone clearance were studied retrospectively. recurrent cbd stone, was defined by the confirmation of the presence of cbd stone at least months after previous complete cbd stone clearance by es. the risk factors for recurrent cbd stones and mean time interval between initial es and stone recurrence were analyzed. results: in total, patients we included. the median follow up period was months. recurrent cbd stones appeared in / ( . %) patients after a median time interval of ( - ) months following es. stone recurrences were observed on multiple occasions in patients ( . %). on the univariate analysis, the significant risk factors related to recurrent cbd stone were male sex (p= . ), previous history of cholecystectomy (p= . ) multiple cbd stones (p= . ), large cbd stone (p= . ) the presence of periampulary diverticulum (p= . ) and stone crushing using mechanical lithotripsy (p= . ) conclusion: recurrence of cbd stones is an identified long-term risk after es and stone clearance. background: laparoscopic cholecystectomy during advanced pregnancy is challenging due to the limited intraabdominal space. patients may be at increased risk for developing trocar site hernia. case report: a year old hispanic female in her th week of pregnancy came to the er with acute right upper quadrant pain. due to lack of accessibility she had poor prenatal care. she had mildly elevated amylase but normal lfts and ultrasound showed some gallbladder wall thickening suggestive for acute cholecystitis and no dilated biliary duct. fetal ultrasound was normal. she was admitted to the hospital and started on antibiotics, obstetrics was consulted. her amylase peaked at [ u/l but then normalized and indication for laparoscopic cholecystectomy was made. mrcp and ercp were not performed as it was assumed that the patient had passed a stone. five mm trocars were placed in the luq and the umbilicus and a teleflex minigrasper between the tow. the uterus was found at the umbilical level. the gb was pulled out and the serosa was incised on both sides and a window was created behind the gb midportion and widened towards infundibulum and fundus. there was gb wall thickening and edema. the critical view was obtained and the cystic artery and duct were clipped and divided. the common bile duct appeared normal and no ioc was done. the specimen was retrieved through the luq port site using a mm endobag after dilatation to . cm due to the presence of two large stones. the port site fascia was closed using a suture passer. the postoperative course was uneventful and both mother and baby were well at the two weeks follow up. discussion: in case of biliary pancreatitis during pregnancy, lc should be performed and if ultrasound shows a normal biliary system and amylase/lipase normalize, mrcp/ercp and ioc may be avoidable to protect the baby. lc with two ports is feasible during pregnancy. removal of the specimen through a lateral abdominal wall site may help prevent an umbilical port site hernia in this patient population. s surg endosc ( ) :s -s introduction: splenic abscess is a rare, potentially lethal condition, with autopsy studies showing incidence rates between . - . %. mortality rates ranging from to % making early diagnosis and prompt intervention vital. several case reports have documented post surgical splenic abscess, most notably after laparoscopic sleeve gastrectomy. to the best of our knowledge, there has not been any reported cases of splenic abscess arising after laparoscopic cholecystectomy. it is important to remember this disease process for expeditious targeted treatment in future cases. case presentation: a year-old female with past medical history significant for cholilithiasis, hypertension, and hyperlipidemia presented to the emergency department (ed) with a chief complaint of abdominal pain for two days. labs and imaging were obtained which confirmed the diagnosis of choledocholithiasis and pancreatitis. ercp was performed which showed a . cm stone causing obstruction, with several other smaller filling defects. the stones were removed after sphincterotomy. post procedurally, the patient underwent an uncomplicated laparoscopic cholecystectomy on hospital day (hd) # . post operatively, the patient had persistent leukocytosis peaking at . thousand on postoperative day (pod) # . a ct scan was performed which showed a rim-enhancing splenic collection measuring . . cm suggestive of an abscess. interventional radiology was consulted and aspirated ml of purulent fluid. cultures grew out klebsiella pneumoniae and enterobacter cloacae complex, and the patient was discharged home on zosyn. discussion: laparoscopic cholecystectomy has become the cornerstone in treatment of symptomatic biliary colic and acute cholecystitis. of the many recognized complications of laparoscopic cholecystectomy, splenic abscess has not yet been reported in current literature. the nonspecific signs and symptoms of splenic abscess make clinical diagnosis difficult. the classic triad of fever, palpable spleen and left upper quadrant pain are only seen in about two-thirds of patients. ct scan has been shown to be the most sensitive imaging modality for diagnosis of splenic abscess. current treatment options for splenic abscess are broken down into two subsets: percutaneous and surgical intervention. percutaneous treatment includes image guided aspiration with or without placement of drainage catheter. surgical intervention can be either laparoscopic or open and includes drainage of abscess with splenectomy or splenic conservation. the best treatment option remains unclear, and there is lacking prospective data demonstrating which modality is superior. introduction: laparoscopic subtotal cholecystectomy is widely accepted as a safe alternative to the conventional laparoscopic cholecystectomy in case of acute cholecystitis with frozen calot's triangle. the remnant stump of the gallbladder may be either sutured or looped. however, there are limited studies comparing the outcomes of the two techniques. the present study is aimed at comparing loop and suture closure of the gall bladder stump. methods: a retrospective analysis of our prospectively maintained database revealed that between january and december . patients underwent laparoscopic subtotal cholecystectomy for acute cholecystitis, chronic cholecystitis or empyema gallbladder with frozen calot's triangle. the decision to use endoloop or sutures for stump closure was made intra-operatively after dividing the gallbladder through the infundibulum. a no. sized drain was kept in all the cases. the patients were discharged with drain in situ, and were reviewed on post-operative day during which an ultrasound was done and drain removed if the progress was satisfactory. the intra-operative and post-operative data between the two groups were recorded and analyzed. results: endoloop closure was performed in patients and suture closure using . ethibond was done in patients. three patients from the sutured group had post operative bile leak among which one patient underwent endobiliary stenting. the other were managed conservatively while the drain had to be retained for weeks. two patients in the endoloop group were detected to have retained stone in the remnant gallbladder cuff among which one had recurrent cholecystitis requiring laparoscopic completion cholecystectomy. none of the patients had bile duct injury or surgical site infection. mean post operative stay was . + . days, did not significantly vary between the groups. suturing needed more surgical expertise and had prolonged operative time than endoloop ( + min versus + min, p= . ). conclusion: suture or loop closure of the remnant gallbladder after subtotal cholecystectomy are equally effective. suturing the stump may be associated with increased incidence of biliary leak while endoloop may have higher incidence of retained gallstones. the choice between the two may be made intra-operatively based on the surgeon's expertise and preference. background and aim: in recent years, due to the spread of laparoscopic cholecystectomy, bile duct injury as its complication has been reported at a certain frequency. current surgical treatments include ) suturing and closing the injured part laparoscopically during surgery, ) transitioning to laparotomy and closing the suture, ) inserting a tube such as t-tube under the laparotomy, ) bile duct-intestinal anastomosis under the laparotomy, etc. are taken into consideration. regardless of which treatment method, it is not a definite ideal treatment. we have developed a bioabsorbable material (caprolactone: lactic acid ( : ) polymer reinforced with polyglycolic acid fiber and designed to be absorbed in about weeks). at this conference, we would like to talk about the current state and problems of development of minimally invasive therapy for biliary damaged area using bioabsorbable materials we developed. method: in order to overcome the problem of the current bile duct injury cure method, we have been developed, a) a method of closing a perforation part endoscopically from the luminal side of a bile duct (a covered stent using a bioabsorbable material in the damaged part), b) develop a method of closing the biliary duct injury under the laparoscope from the outside of the bile duct (adhering the bioabsorbable sheet to the bile duct perforation using a biocompatible adhesive). results: experimental results of suturing the bioabsorbable material in the biliary duct in surgery of laparotomy were able to regenerate the bile duct without stenosis in the damaged area. however, various adhesives were tried to bond the sheet of this bioabsorbable material and the native bile duct under the endoscope, but at the moment, there is no glue that will allow the sheet to be adhered readily and reliably where there is moisture to a certain extent. a tool for delivering the sheet from the bile duct into the injured part is under development and good results are obtained at present. conclusion: it is possible to regenerate the bile duct without constriction using a bioabsorbable material. it is difficult to laparoscopically adhere to the injured part of the bile duct, but we hope that it will be possible in the near future to develop further adhesives. s surg endosc ( ) , - kg/m (c) and more than kg/m (d). we made a . -cm longitudinal skin incision within the umbilicus. a wound retractor and a surgical glove were applied at that incision. we used the three -mm ports technique. after retracting the gallbladder upward, the cystic duct and artery were divided and identified using pre-bending forceps through the flexible port and laparoscopic coagulating shears (lcs). the cystic artery was dissected using the lcs and the cystic duct was also dissected after clipping. the gallbladder was freed from the liver bed using the lcs, and the specimen was retrieved from the umbilical wound. results: there were conversions to open laparotomy in cases ( . %) and requirement of additional ports in ( . %). the mean age (years), operation time (min), blood loss (ml) and postoperative hospital stay (days) in group a, b, c and d were . , . , . and . (p= . [), . , . , . and . (p= . ), . , . , . and . (p= . ) , and . , . , . , and . (p= . ), respectively. there was a significant difference in age only. the complications were bile duct injury in one case ( . %) and pneumothorax in two ( . %). conclusion: obesity had no influence of surgical outcomes for performing silc. introduction: recent studies have reported mixed outcomes when comparing surgeon case volume and laparoscopic cholecystectomy (lc) outcomes. formal minimally invasive surgical training (mist) has been shown to be associated with shorter post-operative length of stay (los), but no difference in major adverse events such as bile leak, bile duct injury, intra-abdominal abscess formation, and death. we aim to determine -day rates of major adverse events after lc in a university hospital setting, to identify significant associated risk factors, and to determine if mist or surgeon volume are associated with differences in los and major adverse events. methods: we conducted a single-center retrospective review of , cholecystectomies performed over a seven-year period ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) . characteristics and outcomes were compared using chi squared or rank sum tests. multivariable regression modeling was used to determine independent associations with the two main outcomes, major adverse events and los. results: we identified , adults who underwent lc during the study period, with a median age of , and % women. about % (n= ) of patients had a los[ day and . % (n= ) were re-admitted within the first days after surgery for any reason. within days of lc, . % (n= ) of patients suffered from one or more major adverse events. this includes . % (n= ) of patients with bile duct injury, . % (n= ) of patients with bile leak, . % (n= ) of patients with intra-abdominal abscess, and . % (n= ) of patients died for reasons related to their procedure or post-operative recovery. table shows the characteristics of the patients and procedures with a comparison of the patients with an adverse event versus those without one. in univariate analysis, high annual surgical volume ( + cases/year) and procedure urgency were found to be significant predictors of adverse events and los, however, mist was not. in multivariable analysis, controlling for significant univariate predictors, urgent or emergent cases were associated with a -fold increase in odds of an adverse event (or= . introduction: laparoscopic cholecystectomy is an extremely common procedure in the united states, with over , cases performed annually. despite the procedure's overall safety, there has been some evidence that tobacco use is associated with increased risk of wound infection after lc. this retrospective chart review sought to examine whether tobacco use is associated with increased complications following laparoscopic cholecystectomy within a high-volume healthcare system. methods: after irb approval, of approximately , cholecystectomies performed within one four-hospital system between and were randomly selected, and patient charts were retrospectively reviewed. pre-, intra-, and postoperative data were collected, including all complications within days. tobacco use cohorts were defined as follows: never, former (any historical tobacco use), and current (active tobacco use within year of surgery) per the acs nsqip surgical risk guidelines. following preliminary data analysis, multivariable logistic regression models were generated to identify whether tobacco use was predictive of outcomes of interest. of the cases analyzed, patients ( . %) were never smokers; . % were former smokers, and . % were current tobacco users or had quit less than months prior to surgery. there were surgical site infections, one wound dehiscence, one port site hernia, three common bile duct injuries, and medical complications requiring prolonged hospitalization or readmission within days. current tobacco users were significantly more likely to undergo urgent surgery (following emergency admission or direct admission to the hospital) than former or nonsmokers. however, there was no difference between cohorts for prolonged duration of surgery, conversion to an open procedure, surgical site infection, wound dehiscence or hernia, common bile duct injury, or other medical complication. there was no significant difference between cohorts when all postoperative complications were pooled. conclusions: there does not appear to be a significant difference in -day surgical outcomes or complications in active tobacco users vs. former or non-users. although studies in other surgical settings have indicated a possible reduction in complications if patients abstained from smoking prior to surgery, this may not be beneficial in laparoscopic cholecystectomy. moreover, as current tobacco use appears to be associated with higher rates of urgent surgery, these patients may not be able to stop smoking prior to an elective procedure. prospective studies to further clarify whether there is any benefit towards tobacco cessation prior to lc may be valuable. , [ , [ respectively ( - ) , cyfra were . , . , . respectively ( - . ) . afp and cea were negative. as for this patient, he is of high risk of hepatobiliary system diseases. introduction: thymoma is one of the rare tumor entity benign or malignant arsisng from the epithelial cells of thymus gland, frequently associated with neuromuscular disorder myasthenia gravis. so, we are presenting this rare case of thymoma with myasthenia gravis in our institute. methods: we operated a single patient of thymoma in a case of myasthenia gravis by video assissted thoracoscopic approach. results: operative time- min, intraoperative blood loss − ml, post operative analgesia requirement in form of nsaids is for days, no ventilatory support required post operatively, with follow up reduction in achr ab from nmol/l to nmol/l and reduction in symptoms in form of reduced ptosis. conclusion: thoracoscopic thymectomy is feasible and safe in terms less operative time, less post operative pain and analgesia requirement and no post operative ventilatory support requirement. carter c lebares, md, stanley j rogers, md; ucsf background: duodenal fistulas are uncommon but morbid complications of acute necrotizing pancreatitis. if percutaneous drainage fails, surgical correction via roux-en-y diversion or pancreaticoduodenectomy can be required. while self-expanding metal stents have been tried, complications like migration and perforation have limited such use. endoscopic transmural stents have successfully treated fistulas of the stomach, particularly post-sleeve gastrectomy. here we present a case of endoscopic transmural stents used to treat a non-resolving duodenal fistula following acute necrotizing pancreatitis. methods: under general anesthesia, using a standard adult gastroscope, the fistula was identified in the second portion of the duodenum (fig. ) . a flexible-tipped guide wire was used to identify the fistula tract and two fr cm double pigtail biliary stents were deployed ( fig. ) with positioning verified under fluoroscopy. two weeks later these were removed and a single stent deployed into the visibly smaller tract (fig. ). two weeks after that, the single stent was removed and contrast medium was injected under fluoroscopic visualization, demonstrating resolution of the fistula (fig. ) . case: this patient is a year old woman with hypertension and congenital hearing loss who underwent a cholecystectomy for biliary colic and subsequent ercp with sphincterotomy for retained stone. this was complicated by acute pancreatitis which progressed to severe necrotizing pancreatitis with infected retroperitoneal necrosis. percutaneous drainage yielded initial improvement but a persistent moderate collection ( cc per day) lead to the identification of a fistula in the second part of the duodenum. repositioning and exchange of percutaneous drains over weeks did not hasten resolution. endoscopic transmural pigtail stents were tried after visualization of a large ( - mm diameter) fistula tract. stents were utilized as described in methods, with a total of three endoscopic interventions, at week intervals, resulting in resolution of the fistula as evidenced by contrast injection into the duodenum under fluoroscopy and subsequent ct scan with oral contrast. the patient's symptoms resolved and she was tolerating a normal diet. she remained thus at month follow-up. conclusion: this case demonstrates the benefit of endoscopic transmural stents for the resolution of duodenal fistulas, expanding the utility of this technique to address leaks and fistulas of the upper gastrointestinal tract. further study is warranted to clarify the timing and adjuncts to optimize the use of this promising approach. totally laparoscopic alpps combined with the microwave ablation for a patient with a huge hcc hua zhang; department of hepatopancreatobiliary surgery, west china hospital, sichuan university introduction: associating liver partition and portal vein ligation for staged hepatectomy (alpps) is a novel technique for resecting hepatic tumors that were previously considered unresectable due to the insufficient future liver remnant (flr) which may result in postoperative liver failure (plf). the procedure has been accepted and modified in many medical centers worldwide. but reports about the laparoscopic alpps were rare. this study aimed to report a totally alpps combined with microwave ablation for a patient with huge hcc and confirm the feasibility of laparoscopic alpps. methods: a -year-old man had complained of -year history of right upper abdominal pain, and the syndrome was worsened in recent month. abdominal enhanced computed tomography (ct) imaging revealed a cm solid mass in right lobe of liver with non-uniform and unclear boundary, the right posterior branch of the portal vein was invaded. in addition, a small lesion was simultaneous found in left lateral lobe of liver. the tumor was evaluated as unresectable due to the flr was only ml ( %). we decided to perform the laparoscopic alpps procedure. first stage including microwave ablation of the lesion in left lobe, cholecystectomy, ligation of the portal vein and transection of liver parenchyma. the second stage was done days later and consisted of laparoscopic right hemihepatectomy. results: the two stages were underwent by laparoscopy successfully. the operation duration was and minutes, respectively. estimated blood loss was and ml. the hospitalization time in intensive care unit was and days. there was no need for transfusion in both stages. the patient was discharged days after the second stage and the total hospitalization time was days. recovery of the patient was uneventful in addition to the incision infection after the second stage which recovered with conservative management. the patient did not show any signs of liver failure. the ct scan before the second stage showed an enlargement of left lobe, the flr was ml ( . %). there was no signs of residual liver disease in the ct scan days after the operation. the patient showed no signs of recurrence or liver failure in the following up period of six months. conclusion: totally laparoscopic alpps combined with microwave ablation is safe and feasible for the multiple hcc which was not resectable. the hypertrophy of remaining liver was fast and can achieve an adequate volume in a short time. introduction: chronic pancreatitis is a benign, irreversible inflammatory disorder characterized by the conversion of the pancreatic parenchyma into fibrous tissue. initial management should be conservative, surgery is applied in case of failure of medical treatment. the development of minimally invasive techniques has made it possible to perform these highly technical procedures in a laparoscopic manner. materials and method: we have the history of patients with and years with chronic pancreatitis and pancreatic lithiasis of difficult handling but intractable pain to those who decided to surgical management. we performed the procedure under general anesthesia, epidural analgesia catheter was placed. neumoperitoneum technique of cali, at mmhg and approach using a mm umbilical port, working ports of and a of mm port,. the pancreas was exposed by a section of the gastrocolic ligament with a mm ultrasonic scalpel, with cephalic retraction of the stomach, opening of a smaller sac and approaching the transpavity of omentum. the ventral surface of the pancreas was exposed from the neck. an incision was made in a pancreas body with a monopolar hook. primary pancreatic duct lumen was identified and the incision was extended longitudinally from the neck to the tail of the pancreas ( cm). roux's y loop was prepared cm from the treitz ligament, with a jejunum section with a mm stapler, roux's loop was transmecoscopically retrocollic, closing the gap of the mesocolon with monocryl. a -cm jejunum-jejunal anastomosis was performed with endo-gia stapler and closure of enterotomy with - polypropylene intracorporeal suture. jejunal (roux) isoperistaltic loop was placed longitudinally at the opening of the main pancreatic duct, and enterotomy was performed with monopolar in antimesenteric segment. the intracorporeal pancreatico and jejunum anastomosis was performed using a lower and an upper plane, with single points of total thickness with ethnobond - . closed drains were placed towards each anastomosis. this procedure was performed in the patients reported. operative time - min complications none operative time - days minimal bleeding drains no retired in both cases at days year follow-up of patients improved pain\ conclusions: minimally invasive surgery is a fundamental tool for the approach and management of patients with biliopancreatic pathologies. the establishment of multidisciplinary groups, offer an excellent alteranativa in the integral management of the patients. surg endosc ( ) gallbladder anatomy is highly variable, and surgeons must be prepared to identify anomalies of form, number, and position. variants include gallbladder agenesis, diverticulum, duplication, bilobed, multiseptate, phrygian cap, ectopic, and hourglass gallbladder. the hourglass gallbladder has been described from the earliest days of cholecystectomy, as morton described a congenital case in , and else thoroughly described the acquired and congenital strictures leading to the hourglass deformity in . we describe a case of an hourglass gallbladder found during one-step endoscopic retrograde cholangiopancreatography (ercp) and laparoscopic cholecystectomy. this year old male presented to an outside hospital with one day of nausea, and constant, severe, epigastric pain that radiated to his back. he endorsed a history of similar pain several times in the past. his abdomen was soft, nontender, and without murphy sign. laboratory evaluation revealed total bilirubin . mg/dl, alkaline phosphatase u/l, ast u/l, alt u/l, and no leukocytosis. ct abdomen and pelvis revealed cholelithiasis, distal choledocholithiasis, intra-and extra-hepatic ductal dilation, and a . centimeter left liver hemangioma. he was transferred for management of choledocholithiasis, and an abdominal ultrasound revealed cholelithiasis, without gallbladder wall thickening or pericholecystic fluid, and a . millimeter common bile duct without choledocholithiasis. he was taken to the operating room for a one-step ercp and laparoscopic cholecystectomy. upon laparoscopy, dense adhesions to the gallbladder were found. after initially attempting to obtain the critical view of safety, we then embarked on the retrograde "top down" dissection. this isolated a spherical structure measuring . . centimeters. two very thin tubular structures were identified, clipped, and transected after we found they were too small to place a cholangiocatheter. the common bile duct appeared to be pulled anteriorly by surrounding inflammation, though this was later found to be the proximal segment of gallbladder. the intra-operative ercp identified a remnant gallbladder with cholelithiasis and no extravasation of contrast. given the unusual anatomy, we completed the operation, ordered a post-operative ct liver and mrcp, and consulted a hepatopancreatobiliary surgeon. a small remnant gallbladder was identified on ct liver, though not on mrcp. completion laparoscopic cholecystectomy with intraoperative cholangiogram and ultrasound was performed on hospital day . this hourglass gallbladder variant likely occurred secondary to chronic fibrosis from cholecystitis, leading to a proximal and distal gallbladder lumen. in anatomic uncertainty, the "top down" dissection, intraoperative cholangiography, ct liver, and expert consultation are safe methods to avoid iatrogenic injury. introduction: endoscopic entero-enteral bypass could change our approach to small bowel obstruction in patients with prohibitively high operative risk. magnetic compression anastomoses have been well-vetted in animal studies, but remain infrequent in humans. isolated cases of successful use in humans include treatment of biliary strictures and esophageal atresia. while endoscopic gastro-enteric magnetic anastomoses have been described, the associated multicenter cohort study was terminated due to serious adverse events. since then, the technology has evolved and recently our own institution reported results of the first in-human trial of magnetic compression anastomosis (magnamosis), deployed through an open approach. here we present the first case of endoscopic delivery of the magnamosis device and the successful creation of an enteroenteral anastomosis for chronic small bowel obstruction in a patient with prohibitively high operative risk. methods: the magnamosis device has previously been approved by the food and drug administration (fda) for use in clinical trial. our institutional review board approved emergency compassionate endoscopic use of the device in this patient due to a non-resolving small bowel resection and prohibitively high operative risk. case: this is a year old man with advanced liver disease, chronic obstructive pulmonary disease, and history of emergent right colectomy with end ileostomy for cecal perforation. he presented with multiple acute on chronic episodes of small bowel obstruction with a stable transition point in the distal ileum, radiographically estimated at centimeters proximal to the ileostomy. endoscopic evaluation through the ileostomy revealed a traversable obstruction with proximally dilated small bowel. the magnets were delivered via endoscopic snare under fluoroscopic guidance and positioned in adjacent loops of bowel on either side of the obstruction (image ). by days post-procedure, healthy villi were visible through the central portion of the mated magnetic rings (image ). by days the magnetic rings were mobile and the anastomosis was widely patent allowing easy passage of the gastroscope (image ), and the patient's symptoms were completely resolved. the rings passed through the ileostomy days post-procedure. at month follow up, the anastomosis was unchanged (image ). conclusion: this case demonstrates the benefit of an endoscopically created magnetic compression anastomosis in a patient with small bowel obstruction and high operative risk. further studies are indicated to evaluate the use of this technique in similar patients or those with malignant obstruct, ion. desiree raygor, md, ruchir puri, md; university of florida health jacksonville cholecystectomy is one of the commonest operations in general surgery [ ] . occasionally chronic cholecystitis can lead to a small contracted gallbladder. this diagnosis can be misleading as it may represent congenital agenesis of the gallbladder [ ] . a -year-old female with a past history of pancreatitis presented with a three day history of right upper quadrant pain associated with nausea and vomiting. upon exam she exhibited tenderness in the right upper quadrant. her leukocyte count and liver function tests were within normal limits. ultrasound revealed a poorly visualized, contracted gallbladder without stones and a dilated common bile duct (cbd). cholescintigraphy revealed non visualization of the gallbladder after two hours, which was suggestive of acute cholecystitis. decision was made to proceed with a laparoscopic cholecystectomy. the abdomen was entered by an open hasson technique and standard trocar placement for a cholecystectomy was performed. on initial inspection, the gallbladder was not readily visible. a structure appearing to be the cbd was present and was mobilized circumferentially (fig. ) . a gauge butterfly cannula was utilized and multiple cholangiographic images were obtained (fig. ). no cystic duct or gallbladder was identified which was suggestive of congenital agenesis of the gallbladder. the patient did well postoperatively, and was discharged home on postoperative day two. the patient's symptoms resolved and she continues to be pain free one month postoperatively. congenital agenesis of the gall bladder is a rare disorder. a high index of suspicion is required especially in the setting of a small contracted gall bladder. if preoperative imaging is inconclusive then diagnostic laparoscopy should be the next step. cholangiogram should be performed routinely to confirm the diagnosis and to rule out an ectopic gall bladder. conversion to open does not offer any distinct advantage, and laparotomy should be avoided if possible given its associated morbidity. there are many reports upper abdominal major arterial aneurysms. however, an aneurysm of left inferior phrenic artery had never been reported. a -year-old woman with liver cirrhosis associated with hepatitis b viral infection was referred to department of surgery for treatment of aneurysm of left inferior phrenic artery. she underwent trans-arterial chemoembolization (tace) for treatment of hepatocellular carcinoma three times, previously. on months after last tace, mm sized highly enhancing nodular lesion of gastric fundus was found on follow-up abdomenpelvis computed tomography (a-p ct). one year later, the size of this lesion increased to mm, and an aneurysm was diagnosed. she underwent angiography and attempted embolization with an aneurysm of the left inferior phrenic artery, but access failed. we performed a laparoscopic vessel ligation. she recovered with no complication and discharged on the th postoperative day. s surg endosc ( ) :s -s yousef almuhanna, vatsal trivedi, fady balaa; university of ottawa a years old female, g and weeks pregnant, was brought to the hospital by ems, after being found on the floor in her toilette surrounded by vomitus and urine. mother-inlaw, who happens to be at the house that time, have heard severe retching followed by a loud bang sound. firefighters have found no pulse and therefore started cpr. return of spontaneous circulation was achieved, yet unfortunately, she had arrested again minutes prior to arrival to er. pocus assessment showed large rvot, and therefore tpa was started on the assumption of pulmonary embolism. upon arrival of blood work, it was found that her hemoglobin had dropped from to . fast was repeated showing moderate to severe amount of free fluid in the morrison's pouch and pelvis. she was then taken to the operating theatre, had undergone laparotomy showing liver segment ii injury. pringle's maneuver and aortic clamping did not control the bleed, therefore finger fracture and venous clips were used to temporary minimize the bleed, and head to interventional radiology suite. after multiple attempts to control the bleed, and the massive transfusion, she vital signs were not maintained, and had arrested afterwards. sarrath sutthipong, md, chumpunut chuthanan, md, chinnavat sutthivana, md, petch kasetsuwan, md; bhumibol adulyadej hospital, bangkok, thailand background: mesenteric panniculitis (mp) is a rare, benign and chronic fibrosing inflammatory disease that affects the adipose tissue of the mesentery of the small bowel and colon. the specific etiology is unknown and no clear information about the incidence. the diagnosis is suggested by ct and is usually confirmed by surgical biopsy. treatment is based on some selected drugs. surgical resection is sometimes attempted for definitive therapy, although the surgical approach is often limited. we reported a case of the mp diagnosed with ct and surgical biopsy by laparoscopic approach. case report: -year-old woman with months history of chronic abdominal pain, mainly localized in the sub-epigastrium, intermittent and mild. she had anorexia but no weight loss or change in bowel habits. no history of medical illness or surgery. the physical examination was unremarkable, except for palpation of ill-defined mass about cm at mid-abdomen, firm, smooth surface with mild tenderness. the laboratory profile and tumor marker were normal. ct of the abdomen, which showed focal heterogeneous enhancement of the mesenteric fat with stranding ( . . cm) with multiple internal subcentimeter lns in the supraumbilical area, which was probably inflammatory in origin and suggestive of mp. f-fdg pet/ct showed faint fdg uptake in multiple mesenteric lns. the patient was subsequently underwent diagnostic laparoscopy with biopsy. intra-operative finding showed a fat-like surface of yellowish mass at mesentery of jejunal segment, incisional biopsy was performed laparoscopically. the histology showed adipose tissue with areas of fat necrosis, fibrosis, foamy macrophages infiltration and predominant chronic inflammation, no evidence of malignancy. ihc studies (including cd , s- , cd and cd ) were performed and the result was compatible with reactive process. treatment was started with mg prednisone once daily and planned for follow-up with repeated ct scan. discussion: mp involves the small bowel mesentery in over % of cases. the diagnosis is made by pathologic findings: fibrosis, chronic inflammation and fatty infiltration. the differential diagnosis is broad and has been associated with malignancies such as lymphoma, well-differentiated liposarcoma and melanoma. the imaging appearance varies depending on the predominant tissue component. a definitive diagnosis is biopsy but open biopsy is not always necessary. no data of laparoscopic biopsy, which has been reported previously. treatment has been reserved for symptomatic cases with a variety of drugs. our case was started on oral corticosteroid treatment and waited for responsive evaluation. background: laparoscopic appendectomy is the gold standard for treatment of acute appendicitis. stapled closure of the appendiceal stump is often performed and has been shown to have several advantages. few prior cases have been reported demonstrating complications from free staples left within the abdominal cavity after the laparoscopic stapler has been fired. case report: a previously healthy year old female initially underwent laparoscopic appendectomy for acute uncomplicated appendicitis during which the appendix and mesoappendix were divided using laparoscopic gastrointestinal anastomosis (gia) staplers. her initial postoperative recovery was uncomplicated and she was discharged home the same day. the patient returned to the emergency department on postoperative day with one day of sharp mid-abdominal pain, obstipation, and emesis. her abdomen was distended and mildly tender but not peritoneal. she was afebrile but was found to have a leukocytosis of . . ct demonstrated twisted loops of dilated small bowel in the right lower quadrant with two transition points, suggestive of internal hernia with closed loop bowel obstruction. diagnostic laparoscopy was performed through the three prior appendectomy incisions. an adhesion was noted between the veil of treves and the mesentery of a more proximal loop of ileum caused by a solitary free closed staple, remote from the staple lines, resulting in an internal hernia containing several loops of ileum ( fig. ). the hernia was reduced, and the small bowel was noted to have early ischemic discoloration. the adhesion was lysed by removing the staple from both structures to prevent recurrence. through the remainder of the procedure, the compromised loops of bowel began to peristalse and the color normalized. the procedure was concluded without resection. the patient recovered on a surgical floor and was discharged home on postoperative day one. conclusion: gastrointestinal staplers are commonly used secondary to ease of use and low complication rate. it is not uncommon to leave free staples in the abdomen during laparoscopy as retrieval can often be more difficult and time consuming. our case is only the second in the literature reporting an internal hernia with closed loop bowel obstruction as a complication of retained staple. choosing the most appropriate size staple load, to reduce the number of extra staples after the fire, and removing as many free staples as possible can prevent potentially devastating complications. video-assisted thoracoscopic pulmonary wedge resection in a patient with hemopytsis and intralobar sequestration: a case report mary k lindemuth, md, subrato j deb, md; the university of oklahoma health science center case report: a -year-old male with history of noonan's syndrome, bronchitis, and asthma presented with acute hemoptysis. while chest x-ray was unremarkable, a computed tomography angiogram of his chest was significant for intralobar pulmonary sequestration in the right lower lobe. the aberrant pulmonary artery originated from the abdominal aorta, immediately proximal to the celiac axis, and coursed through the hiatus in the retroperitoneum. flexible, fiberoptic bronchoscopy revealed blood within the right lower lobe bronchus with no appreciable source. a right video-assisted thoracoscopic approach was taken for wedge resection of the sequestration. twoportal technique was utilized with the patient on single lung ventilation. the sequestration was easily identified; the anomalous pulmonary artery coursed directly to a large, focal area of hemorrhage noted within the lower lobe pulmonary parenchyma, as seen in image [rectangle marking the aberrant artery and oval marking the sequestration]. pathologically, the specimen was noted to be benign lung parenchyma with bronchiectasis and abundant, acute hemorrhage. discussion: pulmonary sequestration (ps) is a rare, congenital bronchopulmonary foregut malformation. literature describes the incidence of ps to be only . - . % of all pulmonary malformations. as ps is most frequently diagnosed during childhood, the occurrence of diagnosis during adulthood is estimated to be less than per , adults. two types (intra-and extralobar) are described, with intralobar sequestration most common and contained within the normal visceral pleura. both types have aberrant systemic arterial blood supply, most frequently from the thoracic aorta. likewise, both types are nonfunctioning lung tissue, as there is no direct communication with the bronchopulmonary tree. the most common presentation is pneumonia, and often patients will have had recurrent symptoms before diagnosis. it is rare to present with hemoptysis, which is understood to be secondary to elevated capillary pressure within the sequestration and then communication through the pores of kohn. while endovascular embolization of the aberrant pulmonary artery has been described as a safe alterative for surgical intervention, the subjects of these studies have primarily been children and long-term outcomes are unknown. the definitive treatment of ps continues to be surgical intervention. the surgeon should strive to leave as much normal lung parenchyma as possible. video-assisted thoracoscopic resection is well tolerated by patients when compared to thoracotomy. however, it is vital for the surgeon to be aware of the potential risk of life-threatening hemorrhage secondary to the sequestration having systemic blood supply that must be controlled and ligated. case report: a years-old female patient with history of an increased mass and weight loss of kilograms in months, associated with vomiting and nausea for eight months. abdominal ultrasound showed an irregular cyst, without solid projections and without signs of flow in doppler, measuring cm. investigation continued with ct scan that showed a large homogeneous cystic lesion with no septum in the abdominopelvic region, possibly mesenteric, measuring . . cm. a laparoscopic approach for resection of the cyst was then performed. the surgery was performed with a patient in the dorsal decubitus, using three trocars: one in the umbilical region ( -mm) for the camera, and where the pneumoperitoneum was created by the hasson open technique under direct vision; and another two located in the epigastrium ( -mm) and in the right upper quadrant ( -mm) . in addition to the mesenteric cyst, a simple cyst in the right ovary and a solid nodule with a lipomatous characteristic of approximately cm in the abdominal cavity were visualized. total resection of the mesenteric cyst with periprancreatic fibrous tissue was performed. the cyst was punctured and its contents fully aspirated. resection of the right ovarian cyst was also performed. at the end of the procedure the mesenteric and ovarian cysts, the nodule, part of the omentum, and the peripancreatic tissue were removed through the -mm trocar at the umbilicus. patient had no further complications, being discharged four days after the procedure. histopathologic result showed a serous cyst in the right ovary, serous cyst in peripancreatic mesentery with chronic inflammatory process and signs of calcification; no signs of malignancy were observed in any specimen. we aimed to present the succesul therapeutic approach utilizing laparoscopy for safely removing a gastrointestinal stromal tumor. depicted is a year old jehova's witness female who presented to the emergency department for evaluation of bitemporal headache and dizziness and found with profound anemia with hemoglobin . and hematocrit . upon arrival to ed. the patient refused blood transfusion as her religious beliefs, jehovah's witness, preclude her from taking blood products. as part of her work up, endoscopy was performed and revealed a large, approximatelly cm, prolapsed, ulcerated, nodular lesion with active bleeding in the cardia of the stomach. this was temporized but the friable tissue, with no single identifiable lesion for clip placement, left the patient at high risk for re-bleeding. she was taken to the operating room and laparoscopic partial gastrectomy with intraoperative esophagogastroduodenoscopy were succefully perfomed, with minimall blood loss and no intra operative complications. patient was discharged on post op day . we present the case of a -year-old male with a history of morbid obesity with an initial bmi of . , who underwent an elective laparoscopic single anastomosis duodenal-ileal bypass with sleeve gastrectomy (sadi-s). postoperatively he developed an anastomotic leak at the duodeno-ileal anastomosis that would not resolve despite reoperation. he was then converted to a roux-en-y gastric bypass (rygb). postoperative imaging failed to reveal any signs of anastomotic leak and the patient was discharged tolerating an oral diet. he returned to the emergency department days later with a cm sub-hepatic collection arising from the duodenal stump from the surgical conversion. interventional radiology percutaneously drained the collection and found a connection between the cavity and the duodenum. using this connection, a percutaneous decompressive duodenostomy drain was successfully inserted into the duodenum using a guidewire through the abscess cavity along with an extra-enteric drain placed within this cavity. the collection was obliterated and the duodenal leak was controlled successfully with percutaneous drainage, bowel rest with parenteral nutrition and broad-spectrum intravenous (iv) antibiotics. the patient was reintroduced to a bariatric clear diet after a week of bowel rest and the abscess drain was then discontinued during the same hospital admission. the patient was discharged with the percutaneous duodenostomy tube which was removed in clinic days later, after the patient tolerated capping trials and imaging failed to reveal any further collections, oral contrast extravasation or distal obstruction. in this article we analyze notable imaging from the case and review current literature on the different management options for a duodenal stump blowout. we also discuss the basics of the sadi-s procedure and conversion of a sadi-s procedure to a rygb. keywords: anastomotic leak, duodenal stump blowout, sadi-s, duodenostomy tube. pancreatopic heterotopia is often an incidental finding on autopsy, but in some cases can lead to abdominal pain, obstruction, or intussusception. we present a case of pancreatic herterotopia mimicking an internal hernia on radiologic imaging. a year old female with seven month history of chronic abdominal pain treated for low back pain and recurrent urinary tract infections. she was found to have a computed tomography (ct) scan concerning for internal hernia and labs consistent with acidosis. she was taken for a laparotomy and did not have an internal hernia, but an exophytic mass in the proximal jejunum. the mass was resected and a stapled side to side jejunojejunostomy was created. on pathologic review, the specimen was found to be pancreatic heterotopia. her post operative course was complicated by an ileus, but was discharged post op day three. at her two week follow up she had minimal incisional pain and at one year follow-up she had resolution of her left upper quadrant abdominal pain. prior to this report, pancreatic heterotopia has never been described as presenting on ct scan as an internal hernia. although uncommon it should remain in the differential when evaluating a patient presenting with abdominal pain and radiologic evidence of obstruction or internal hernia. case report: a -year-old male patient who was diagnosed with high blood pressure at years-old and presented tetraparesis and intense asthenia for six months. blood tests showed hypokalemia, hypernatremia, and suppressed renin activity. ultrasound of the urinary tract was normal. ct scan of the abdomen showed a hypodense nodule with regular margins, measuring . . cm with a density of hu in the non-contrast phase and heterogeneous uptake after the injection of the contrast in the left adrenal gland. thus, the diagnosis of hyperaldosteronism secondary to the left adrenal nodule was confirmed, and surgical resection was indicated. the procedure was performed with the patient in the right lateral decubitus. two -mm and one -mm trocars were used on the left flank, as well as the -mm portal for the camera in the lower right quadrant under direct vision. the pneumoperitoneum was created by the hasson open technique in the transumbilical incision. the procedure consisted of the dissection, isolation and electrocautery of the left renal capsule and the left adrenal region with ultrasonic device, as well as the periadrenal vessels, adjacent lymph nodes and periadrenal and adrenal fat tissue. the surgery was uneventful and the patient had no further complications, being discharged the next day. histopathologic result showed a completely excised adrenocortical adenoma. conclusions: the hybrid minimally invasive approach proved to be safe and effective for this procedure, and the known advantages of minilaparoscopy such as less trauma, better visualization, better dexterity, better aesthetics, and reduced hospital stay were observed. s surg endosc ( ) background: coccidioidomycosis is a fungal infection endemic to the southwestern united states, central america and south america. coccidioides is ubiquitous in many of these endemic regions, with near % seroconversion in some communities. two-thirds of these mycotic infections may be asymptomatic. the most common presentation of coccidioidomycosis consists of "flu-like" symptoms or pneumonia. less than five percent of symptomatic cases progress to disseminated coccidioidomycosis which may involve any organ system. very rarely infection may include the peritoneum. we report a case of coccidioidomycosis with peritoneal involvement in an immunocompetent individual. case: a -year-old male presented to the emergency department with progressive abdominal pain. he was seen and treated for pneumonia in the emergency department one week prior. the patient worked outdoors in arizona and was otherwise healthy with a family history of malignancy and blood disorders. fever, leukocytosis and ascites on computed tomography scan prompted a diagnostic laparoscopy which revealed peritoneal granulomas positive for coccidioides. the patient was treated outpatient with fluconazole. discussion: since this is the th reported case of peritoneal coccidioidomycosis to our knowledge. the patient described in this case report was an otherwise healthy -year-old male; this is incongruent with many of the previously recorded cases which involved disseminated disease in immunocompromised patients. the patient's family history of malignancy and blood disorders suggests a potential underlying genetic predisposition that could account for this abdominal presentation. possible mutations include genes coding for the interleukin- β receptor and the signal transducer and activator of transcription which have been implicated in increased coccidioidomycosis susceptibility. peritoneal infection presents a unique challenge in diagnosis. in these cases coccidioidomycosis may not be suspected due to nonspecific symptoms and imaging, the infrequency of this extra-pulmonary manifestation and clinical characteristics that mimic the presentation of tuberculosis and malignancy. abdominal infections have been misdiagnosed as appendicular abscesses, iliopsoas abscesses, adnexal abscesses and pancreatic masses. consequently, the diagnosis of peritoneal coccidioidomycosis is often made after laparoscopic exploration of the abdomen and histopathology, as it was in this case report. conclusions: coccidioidomycosis incidence is on the rise in endemic areas and it often falls on the surgeon to make the diagnosis in extra-pulmonary cases. the peritoneal subset of coccidioidomycosis should be considered in endemic areas when a young, otherwise healthy patient presents with abdominal pain. failure to recognize the possibility of coccidioidomycosis may lead to unnecessary treatments and procedures. indocyanine green cholangiography to detect anomalous biliary anatomy steven d schwaitzberg, md, gabrielle yee, ms; university at buffalo jacobs school of medicine introduction: common bile duct injury is the most feared complication of cholecystectomy. imaging with indocyanine green (icg) is a safe and effective technique to detect biliary anatomy in open, laparoscopic and robotic surgery. several studies report detecting aberrant biliary anatomy with the use of icg in laparoscopic cholecystectomy with high success rates. by identifying the cystic duct-common hepatic duct confluence before dissecting calot's triangle, icg allows surgeons to perform "virtual" cholangiography at the start of procedures to identify either normal anatomy or possible anatomic variants. it is clear that icg use is an effective tool to achieve the critical view of safety. however, no reports have suggested icg cholangiography as the last operative step in cholecystectomy to identify hidden biliary anomalies and avoid postoperative bile leak complications. case report: we report a novel use of icg cholangiography in visualizing anomalous biliary anatomy prior to closing, thus avoiding potential bile duct leakage. in our case, icg cholangiography was used to fluoresce the common hepatic duct, common bile duct and cystic duct. the cystic duct was transected, and the gallbladder was removed using electrosurgery. at the completion of the gallbladder removal, the liver was elevated to inspect the clips on the cystic duct and artery. at this point, near infrared imaging was reinitiated, and a small mm structure was noted to fluoresce next to the cystic artery. this structure was identified using white light and subsequently clipped. discussion: the use of icg in this context after the completion of the cholecystectomy facilitated the identification of a small hepatocystic or aberrant duct, which would have likely leaked bile sometime in the postoperative period. based on our experience, we recommend one additional routine near infrared viewing to identify small structures or potential leaks at the completion of cholecystectomy. improved visualization of the extrahepatic biliary anatomy by icg has the potential to translate into improved clinical outcomes. solitary fibrous tumors (sft) are uncommon fibroblastic mesenchymal neoplasms that display a wide range of histologic behaviors. these tumors, which are estimated to account for % of all soft tissue neoplasms, typically follow a benign clinical course. however, it is estimated that - % of sfts are malignant and demonstrate aggressive behavior with local recurrence and metastasis up to several years after surgical resection. we report a case of sft arising from the stomach, which is an exceptionally rare finding and has been reported only six times in the literature. additionally, this tumor was associated with dedifferentiation into undifferentiated pleomorphic sarcoma. to our knowledge, there are no documented cases of a malignant sft arising from the stomach to demonstrate dedifferentiation into an undifferentiated pleomorphic sarcoma. a -year-old male presented to the emergency department with vague complaints of right-sided flank pain. the patient had a history of nephrolithiasis and underwent a ct abdomen. this scan revealed a large heterogeneous mass in the left upper quadrant. the patient underwent endoscopic ultrasonography with fine needle aspiration of the mass, which stained strongly for cd . gastrointestinal stromal tumor (gist) was the favored diagnosis as it is by far the most common mesenchymal neoplasm of the stomach, especially cd positive spindle cell neoplasm. accordingly, the patient began treatment with imatinib; however, after four weeks of therapy, there was no significant radiologic regression. a second biopsy was performed and the specimen was sent for stat immunohistochemistry, which revealed diffuse strong nuclear positivity. a diagnosis of solitary fibrous tumor was provided. surgical resection of the tumor was performed, which measured . cm. the patient was to undergo surveillance imaging every to months post-operatively. surveillance scan showed solitary metastatic disease in the left lateral segment of the liver. he underwent left lateral segmentectomy with an uneventful recovery. our case was complicated by diagnostic dilemma with gist, highlighting the challenges of diagnosing and characterizing sfts. dedifferentiation, or the abrupt transition from a classic sft into a high-grade sarcoma, is a particularly concerning finding in our case, as it is associated with a worse prognosis than classic malignant sft. the stat marker by immunohistochemistry is very specific for sft and may have aided in the diagnosis earlier. therefore, it is imperative to keep solitary fibrous tumor, albeit exceedingly rare, in the differential diagnosis of mesenchymal neoplasms of the stomach. appendiceal diverticulitits is an uncommon pathology that can clinically mimic acute appendicitis. some radiographic distinctions have been reported, but final pathologic examination of the surgical specimen is required to confirm the diagnosis. symptoms are often more mild, which can lead to a delayed diagnosis, and increases the risk of severe complications such as perforation. a year old female presented with a three day history of right lower quadrant pain. she described the pain as constant and radiating to the left lower quadrant. associated symptoms included nausea and vomiting, and decreased appetite; she denied fevers or diarrhea. the patient had no significant past medical history, and surgical history was significant for a total nephrectomy for living donor kidney transplant to her mother. on physical exam she was tender in the right lower quadrant with rebound and a positive rosving's sign. all laboratory results were unremarkable, and she was hemodynamically stable. ct scan was performed and demonstrated a dilated fluid filled appendix with surrounding inflammatory change without abscess or free intra-peritoneal air. she was subsequently admitted to the hospital, made npo, started on iv antibiotics, and was taken to the operating room where she underwent an uncomplicated laparoscopic appendectomy. post-operatively, her hospital course was unremarkable. pathology revealed acute suppurative appendicitis secondary to an acutely inflamed appendiceal diverticula, consistent with a final diagnosis of acute appendiceal diverticulitis. appendiceal diverticulitis should be considered in patients presenting with acute right lower quadrant abdominal pain. although some consider appendiceal diverticulitis a variant of acute appendicitis, it is important to distinguish between the two diagnoses. appendiceal diverticulitis has a higher rate of complications, including perforation, and is associated with a higher risk of neoplasm, particularly mucinous adenomas and carcinoid tumors. appendectomy should be performed in all cases in order to obtain appropriate pathological examination and rule out coexistent neoplasms. laparoscopic appendectomy is a safe and appropriate approach to treatment of appendiceal diverticulitis. upper gi endoscopy and biopsy showed a gastrointestinal stromal tumor (gist) in the stomach. a videolaparoscopic partial gastrectomy was then proposed. the surgery was performed with the patient in the right lateral decubitus. two -mm minilaparoscopic trocars, a -mm conventional trocar for an ultrasonic instrument and a -mm trocar in the umbilical region for the camera were used. pneumoperitoneum was created using the hasson open technique under direct vision. trans-operatory endoscopy was perfomed to identify the tumor easily. initially, the ultrasonic device released the large omentum, and, then, the tumor was resected in the body of the stomach. the gastric wall was manually sutured with a - vicryl, and the tumor was removed in an endobag through the -mm incision in the umbilicus. the surgery was uneventful, with a total time of minutes. the patient had no further complications, being discharged two days after the procedure with good clinical conditions. histopathological result showed a free margins gist. conclusion: the minimally invasive approach proved to be safe and effective for this procedure. the known advantages of video-surgery such as less trauma, better visualization, increased dexterity, better esthetics, and less postoperative recovery time were confirmed. the upper gi endoscopy contributed to improve the safety and efficacy of the procedure, allowing a more precise resection of the gist, as well as the intragastric review of the suture line at the end of the surgery. background: portal vein thrombosis (pvt) is a rare post-operative complication, which has been associated with a wide range of precipitating factors. most commonly described associated conditions include; cirrhosis, bacteremia, myeloproliferative disorders and hypercoagulable states. pvt most frequently occurs as a complication after hepatobiliary surgery, and although possible, very few cases have been documented occurring after laparoscopic surgery of the gastrointestinal tract. herein, we describe a case of pvt in a patient who underwent elective laparoscopic right hemicolectomy and was treated successfully at our center. case: a year-old female with past medical history of depression, migraines and endometriosis underwent an uncomplicated laparoscopic right hemicolectomy at our facility, for recurrent rightsided diverticulitis. she had suffered previous episodes of diverticulitis and desired definitive surgical treatment. her hospital course was uneventful and she was discharged to home on postoperative day . on post-operative day , she presented to the emergency department complaining of severe abdominal pain, back pain and nausea. computed tomography of abdomen and pelvis revealed pvt. she was initiated on therapeutic anticoagulation with heparin. hematology was consulted for hypercoagulable workup. further investigation revealed that she had a family history of a brother who had had a lower extremity deep venous thrombosis, with negative hypercoagulable workup. she had also previously been taking leuprolide and conjugated estrogen and medroxyprogesterone for her endometriosis. she was ultimately found to have a heterozygous prothrombin g a gene mutation. her anticoagulation was bridged to coumadin and she was discharged home. she has recovered as expected, without any further complications. discussion: although more common in patients with cirrhosis after hepatobiliary surgery, pvt is a rare complication that can occur after virtually all types laparoscopic surgeries, including elective right hemicolectomy. patients may be completely asymptomatic, or present with a broad spectrum of symptoms including; severe abdominal pain, fever, diarrhea, or gastrointestinal bleeding. physicians should be aware of this possible complication, since early diagnosis and treatment is imperative to prevent life-threatening complications, such as intestinal ischemia and perforation. a detailed medical and family history is imperative, and all patients with post-operative pvt should undergo complete hypercoagulability workup. this is a case of a year old male with a previous history of a redo-hiatal hernia years prior who presented with two episodes of upper gastrointestinal bleeding with no identifiable source noted on both endoscopy and angiography. during his second admission, initial hemoglobin was . g/dl and endoscopy performed showed massive amount of blood in the stomach. continuous oozing was seen originating in the fundus area but no clear source could be identified. empiric epinephrine was injected to the area but failed to achieve hemostasis. angiography was also negative. repeat endoscopy performed showed no active bleeding, however, distention of the wrap into the gastric cavity was observed. the patient re-bled and was taken to the operating room emergently after failed attempt at endoscopic control. the patient underwent proximal gastrectomy after intra-operative gastrostomy and exploration was unable to identify a bleeding source. the patient was left with an open abdomen and in discontinuity while resuscitation was performed in the surgical intensive care unit. he subsequently underwent a roux-en-y reconstruction and gastrostomy tube placement via the distal gastric remnant. upper gastrointestinal series performed demonstrated absence of leak, and the patient was started on a liquid diet supplemented with tube feeding. his recovery was uneventful and he was discharged home in stable condition. pathology revealed gastric ischemia at the base of the wrap making it impossible to visualize through endoscopy. on reviewing the literature, gastric ulcers and ischemia have been previously described. incidence was up to % and their onset of presentation ranged from the early post-operative period up to years. most were located in the lesser curvature. the exact pathophysiology for its occurrence is not completely understood. factors hypothesized include technical aspect of the fundoplication causing inappropriate tension, vessel disruption and ischemia, and injury to the vagus nerve affecting gastric emptying which was thought to increase gastrin secretion. treatment includes medical management with proton pump inhibitors; however, few cases describe antrectomy with inclusion of the bleeding ulcer. our case presents failed medical and endoscopic management. we recommend take down of the fundoplication in hemodynamically stable patients to completely evaluate the gastric mucosa, identify, and address the source of bleeding. otherwise emergent cases will require staged gastrectomy including the wrap followed by roux-en-y reconstruction. acalculous cholecystitis associated with a large periampullary duodenal diverticulum: a case report peng yu, md, phd, austin iovoli, aaron hoffman, md; department of surgery, suny buffalo, kaleida health system, buffalo, ny introduction: periampullary diverticulum (pad) could compress common bile duct (cbd), and consequently cause obstructive jaundice and cholangitis as few publications have documented. here we first report an acalculous cholecystitis associated with a pad-related cbd obstruction. case: the patient was a -year-old female with a past surgical history of laparoscopic sleeve gastrectomy who presented at the emergency room with upper abdominal pain and vomiting for one day, associated with leukocytosis and left shift. serum total bilirubin raised up to . mg/dl on hospital day (hd) . ct, ultrasound, and mrcp images confirmed a distended, wall-thickening gallbladder with pericholecystic fluid, and a significantly dilated cbd at . cm of diameter ( fig. ) , without cholelithiasis or choledocholithiasis. ercp was unable to be completed due to the post-gastrectomy anatomy and the failure in cannulation into the ampulla which embedded in a large foodimpacted pad (fig. ). on hd , the patient underwent a diagnostic laparoscopy and an intra-operative cholangiogram which confirmed a mildly inflamed edematous gallbladder, and a . . cm large pad with a narrow neck that was distorting the distal cbd (fig. ). since the patient's bilirubin level had been improving, we decided to only do a laparoscopic cholecystectomy. intraoperatively an anatomic variation of the cystic artery encircling the cystic duct ( fig. ) was also identified. postoperatively the patient recovered well during the thereafter inpatient course and at the postoperative -week outpatient follow-up. the pathology of the excised gallbladder confirmed cholecystitis without cholelithiasis. discussion: lemmel's syndrome is defined, in the absence of cholelithiasis or other detectable obstacle, by obstructive jaundice due to pad. since lemmel described this duodenal-diverticulum-obstructive jaundice in , there still have been very few cases reported or investigated. to date there is no report describing the association of acalculous cholecystitis with lemmel's syndrome. this patient's mild acalculous cholecystitis probably attributed to the biliary obstruction and consequent gallbladder hydrops. her symptoms could be from either acalculous cholecystitis or intermittently worsening biliary obstruction. in this case, the contribution of the anatomic variation of the cystic artery is unclear. in the future, if this patient's symptoms recur, the treatment plans for her will be sphincterotomy, removal of the impacted food in the pad, or diverticulectomy. accidental fish bone ingestion masquerading as acute abdomen aim: to report a case of fish bone ingestion masquerading as acute abdomen. case report: a years old female patient presented with complaints of severe abdominal pain since days. there was no history of associated nausea or vomiting, fever or altered in bowel habits. on examination patient had tenderness and guarding localized to the right iliac fossa. blood investigations revealed raised inflammatory markers. ultrasound whole abdomen and contrast enhanced computed tomography (cect) were normal. patient was managed conservatively but in view of persistence of symptoms a triple puncture diagnostic laparoscopy was performed on day of admission. omental inflammation with soapy appendix was found and appendicectomy was performed. on further assessment a foreign body was also found in the ileum which was removed and identified as a fish bone. patient had a satisfactory post operative recovery and was discharged in stable condition. discussion: acute abdomen due to fish bone ingestion is not a very common occurrence. unfortunately the history is often non-specific and these people can be misdiagnosed with acute appendicitis & other pathologies. ct scans can be useful to aid diagnostics. it is however not fully sensitive in detecting complications arising from fishbone ingestion. conclusion: any patient with acute abdomen, with non-specific history and normal imaging may still benefit from a diagnostic laparoscopy. discussion: this patient presented with a bowel obstruction, partial cecal necrosis and neuroendocrine carcinoma. literature suggests that cecal necrosis in the majority of cases is caused by a vascular event, occlusive or non-occlusive. the patient had atherosclerosis and an underlying malignancy which can be associated with prothrombotic states and contributes to an overall risk of thrombosis. the cecum can sustain ischemic ischemic injury in the presence of severe or prolonged hypotension. most frequent causes being decompensated heart failure, hemorrhage, arrhythmia or severe dehydration, only of which was present in this patient. the midgut neuroendocrine tumor is generally located in the terminal ileum, as a fibrotic submucosal tumor cm or less. mesenteric metastases are often larger than the primary tumor and associated with fibrosis which may entrap loops of the small intestine and cause bowel obstruction. this may eventually encase the mesenteric vessels with resulting venous stasis and ischemia in segments of the intestine as seen in this patient. conclusion: cecal necrosis is a rare entity, but its incidence increases with age. isolated cecal necrosis may manifest as a ct-negative appendicitis or a small bowel obstruction in the absence of past surgical history. s surg endosc ( ) laparoscopic transection of the falciform and triangular ligament successfully released the entrapped loop with successful reperfusion by the end of the surgery. in the absence of any prothrombotic comorbidity, the patients were discharged asymptomatic without further anticoagulation. to date only few similar cases have been reported, and most of them described in neonates and pediatric patients. to our knowledge, this cases reporteds in the elderlys. in this patients laparoscopic approach was both diagnostic and therapeutic with the transection the ligament. roberto javier rueda esteban , andres mauricio garcia sierra , felipe perdomo ; universidad de los andes, fundacion santa fe this is a patient´s rare case of spontaneous splenic rupture associated to chronic myeloid leukemia as an uncommon complication. the case report and review of the relevant literature on symptomatology and clinical management is presented. emphasis is made about the importance of including splenic rupture as differential diagnosis for acute abdominal pain, especially in a patient with neoplastic hematopathology, since early treatment increases patient survival and prognosis. esophagectomy is a complex operation associated with serious immediate complications and long term chronic complications. gastric ulcers are a common chronic complication after esophagectomy with gastric conduit reconstruction. these are rarely complicated by significant bleeding or perforation. we report a case of delayed diagnosis of a fistula forming between a gastric conduit and right bronchial tree years after esophagectomy. this was successfully treated using multiple therapeutic approaches including endoscopic localization and resection through a right thoractomy. to the best of our knowledge, our patient is the only survivor from a chronic gastric conduit bronchial fistula. a year old male with type diabetes mellitus, dyslipidemia, asthma and smoking history presented years after an ivory-lewis esophagectomy for a gastrointestinal stromal tumor (gist) with a chronic cough starting years after his esophagectomy followed by multiple episodes of hematoptysis over the next years. the patient was known to have ulcers in his gastric conduit with a massive bleed year after his esophagectomy. repeat endoscopy revealed two large chronic ulcers that had increased in size based on comparison of pictures from endoscopies to years after his esophagectomy despite maximal medical management. the patient presented to numerous specialists at tertiary care centers in canada and the united states. ultimately, in a clinic the patient was observed to cough immediately after the ingestion of water, but not solids leading to a provisional diagnosis of a gastrobronchial fistula. a barium swallow failed to show a fistula (fig. ). however at endoscopy, instillation of saline directed at an ulcer immediately induced a cough, but this was not reproduced when the saline was directed away from the ulcer. the fistula was ultimately demonstrated by placing a wire through the ulcer and visualizing it bronchoscopically in the right superior segmental bronchus . in an effort to pursue a minimally invasive approach two attempts were made to close the fistula with over-the-scope clips (otsc). unfortunately, the patient's symptoms persisted. a wire was placed through the fistula and delivered through the patient's mouth and endotracheal tube. a right thoracotomy allowed access to the conduit, which was opened and the fistula localized using the wire. the fistula was resected and the bronchus closed. at twelve month follow up the patient did not have a recurrent cough or hemoptysis while tolerating a full diet. introduction: roux en-y gastric bypass (rygb) is one of the initial and most studied weight reduction procedures and remains the gold standard for comparison in bariatric surgery clinical outcomes. although rygb is an effective procedure for weight loss, it has been less popular over last several years because of increased morbidity compared to the more utilized vertical sleeve gastrectomy (vsg). early complications of rygb include bleeding, perforation, or leakage. late complications include internal hernias, small bowel obstruction, anastomotic stenosis, marginal ulcers, and gastrogastric fistulas. case report: a -year old female with a past medical history of morbid obesity, diabetes mellitus type , hypertension, gerd, peptic ulcer disease, cholelithiasis, liver dysfunction with ascites, asthma, and a past surgical history of rygb ( years ago) presented to our institution with acute on chronic abdominal pain associated with nausea, vomiting, dysphagia, inability to eat and maintain hydration, and an additional weight loss of about lbs. over the last year. in addition, the patient was a chronic opioid and nsaid user, had an extensive smoking history, and had not followed with her surgeon for years. at the time of presentation, the patient weighed lbs (bmi: . ), had normal vital signs, and appeared cachectic. an upper gastrointestinal study followed by an upper endoscopic examination demonstrated complete obliteration of the gastrojejunal anastomosis and revealed a -cm long gastrogastric fistula originating from the distal end of the gastric pouch to the lesser curvature of the excluded stomach. after conservative measures were initiated to hydrate and metabolically stabilize the patient, the decision was made to proceed with diagnostic laparoscopy and surgical placement of a gastrostomy tube to the gastric remnant. the patient was discharged after tolerating a full liquid diet and gastrostomy tube feedings, for plan of future revision of gastrojejunostomy when optimal nutritional status is achieved. conclusions: late complications of rygb occur at a rate of - %. major risk factors for anastomotic complications include non-compliance, smoking, and opiate and nsaid abuse. though abdominal pain, anastomotic stenosis, marginal ulcers, and fistulas are relatively common late complications of rygb, complete obliteration of the gastrojejunal anastomosis has not been well described in the literature. this case demonstrates the importance of long term follow up post rygb for early diagnosis of late complications and brings attention to this rare, but possible sequele that can arise in patients after rygb. contrast radiograms and upper endoscopic photographs will be presented. introduction: retroperitoneal sarcoma represents approximately - % of all sarcomas and less than . % of all neoplasia. radiotherapy and chemotherapy still do not represent valid therapeutic alternatives; therefore complete surgical resection is the only potential curative treatment modality for retroperitoneal sarcomas. the ability of complete resection of a retroperitoneal sarcoma with tumor grading remains the most important predictor of local recurrence and disease-specific survival. in a patient with a large fibrosarcoma and associated hypoglycemia, assays for insulin-like activity (ila) were found to be high in the extract of tumor tissue, while insulin was not detected in significant concentration neither in the same extract nor in his serum. laparoscopic surgery represents an alternative technique for radical resection of such tumors as a minimally invasive rather than traditional surgery. only few cases were reported in the literature. introduction: roux-en-y gastric bypass (rygb) is a frequently performed bariatric procedure, of which internal hernia (ih) is a known complication. we discuss a rare finding of occult gastric remnant perforation as a result of an obstructed ih in a post bypass patient. methods: we present a case report of a single bariatric surgeon's experience at a tertiary care hospital. literature review of pubmed confirms the unique presentation and operative findings in our patient, as few similar cases have been published. a -year-old male s/p rygb years ago presented to the ed with right upper quadrant pain, nausea, vomiting, and a leukocytosis of , . bmi was . ; weight was lbs. workup included an abdominal ultrasound showing gallbladder distention without signs of cholecystitis. liver function tests were normal. further imaging included a ct scan, remarkable for a paraesophageal hernia (peh) containing the gastric pouch, and an elevated left hemidiaphragm. the scan showed no evidence of ih or bowel obstruction. an upper gi series was additionally obtained, which was also negative for small bowel obstruction. due to unclear etiology for this patient's symptoms or source of leukocytosis, diagnostic laparoscopy was planned. results: intraoperative findings were significant for ih containing dilated small bowel with twisted and incarcerated omentum through the jejunojenunostomy site, as well as a distended gallbladder without acute inflammation. ih was reduced and closed without bowel resection. cholecystectomy was completed. subsequent inspection of the diaphragmatic hiatus revealed uncomplicated herniation of the gastric pouch. in attempts to dissect the left diaphragmatic crus, a large pocket of purulent material was encountered below the left diaphragm in the region of the remnant stomach fundus. methylene blue test and intraoperative endoscopy did not demonstrate any connection to gastric pouch. the purulence was attributed to an occult remnant stomach perforation related to distal obstructed ih. a drain was left in the abscess and the peh was not surgically addressed. patient was discharged on postoperative day . he has not suffered any further complications or recurrent complaints. conclusion: gastric perforation following rygb is an uncommon complication resulting from ih. this diagnosis was missed by preoperative imaging and was only found after thorough laparoscopic investigation. surgeons should maintain a high clinical suspicion of ih in post rygb patients with otherwise unexplained abdominal symptoms, fever, and leukocytosis, even in the absence of confirmatory diagnostic testing. threshold for operative exploration in this clinical setting should remain low. alejandro garza, md, robert alleyn, md, jose almeda, md, ricardo martinez, md; utrgv obesity is an epidemic condition worldwide carrying significant morbidity and mortality. surgical therapy is the only proven effective method to sustain weight loss. among the different surgical procedures gastric bypass is the most effective. during this surgery, most of the stomach is excluded from the upper gastrointestinal tract which makes future evaluation of the same very challenging. this could potentially lead to delay in diagnosis of any pathology in the bypass stomach. gastric cancer is the th most common cause of cancer and cause of cancer death in the united states. we present a case report of a patient who underwent a roux-en-y gastric bypass and went on to developed adenocarcinoma in the gastric remnant year after her surgery. she underwent an exploratory laparotomy, extended antrectomy, subtotal gastrectomy including the gastro-colic ligament, and incidental appendectomy. pathology showed grade undifferentiated adenocarcinoma that penetrated the visceral peritoneum with clear margins. there was angiolymphatic invasion and perineural invasion along with metastatic carcinoma in out of lymph nodes. introduction: polyarteritis nodosa (pan) is a systemic transmural inflammatory vasculitis that affects medium-sized arteries. inflammation of the vessel wall and intimal proliferation creates luminal narrowing which can lead to stenosis and insufficiency. the same inflammatory process causes disruption of the elastic lamina leading to aneurysm formation and possible spontaneous rupture with life-threatening bleeding. multifocal segments of stenosis and aneurysm formation are characteristically identified as a "rosary sign" or "beads on a string". unlike other vasculitides, pan does not involve small arteries or veins, and is not associated with anti-neutrophil cytoplasmic antibodies. we present the case of a year old female with a significant intra-abdominal bleed that was explored and repaired primarily. she was subsequently found on angiogram and postmortem pathology to have findings consistent with pan. case presentation: year old female who presented to the emergency department with abdominal pain followed by hemorrhagic shock and found to have a ruptured left hepatic artery aneurysm during exploratory laparotomy. this aneurysm was suture ligated with a successful outcome. a mesenteric arteriogram was performed the following day and demonstrated lesions consistent with pan including aneurysms of the left gastric branches, right and left hepatic arteries, and beaded appearance of the iliac artery. however, days after hospital discharge she developed massive pulmonary embolism from which she did not recover. postmortem examination confirmed rupture of the left hepatic artery aneurysm in addition to gross anatomical and histological findings consistent with pan. discussion: polyarteritis nodosa is a systemic inflammatory vasculitis that causes intimal proliferation and elastic lamina disruption. this multifocal disruption of the vessel results in aneurysm formation alternating with stenosis creating a characteristic "rosary sign" on imaging. spontaneous rupture of these aneurysms is rare and almost always fatal due to life-threatening hemorrhage. with acutely ruptured aneurysms, prompt diagnosis, aggressive resuscitation, and hemostasis through transarterial embolization or surgery is paramount for patient survival. while acute rupture of an aneurysm as the result of pan is exceedingly rare, it must be considered as a differential diagnosis in the setting of acute abdominal pain and hemodynamic instability. in a patient known to have a medical history of pan and aneurysm formation, routine monitoring and disease progression should be followed. introduction: , surgeries are done annually in the us for small bowel obstruction, which is most commonly caused by intraabdominal adhesions, malignancy, and hernias. . to . % of small bowel obstructions are due to paraduodenal hernias. paraduodenal hernias carry a % lifetime risk of incarceration with a mortality of to %. case report: the patient is a year old male who presented with severe upper abdominal pain for one day. he was passing flatus and had had a bowel movement the previous day. on examination, the patient was tender over the upper abdomen. computed tomography (ct) scan with iv contrast showed a mesenteric swirl sign. the decision was made to perform diagnostic laparoscopy with possible small bowel resection. intraoperatively, a mesenteric defect was noted posterior and to the right of the duodenum, through which bowel was herniating. the herniated bowel and its mesentery were edematous. the defect was sutured closed, taking seromuscular and mesenteric bites through the stomach, jejunum, and mesentery. the patient had an uneventful recovery postoperatively and was discharged on postoperative day . he returned on postoperative day with periumbilical pain which resolved with conservative management. he was followed up weeks postoperatively and was doing well. discussion: paraduodenal hernias are the most common internal hernias. they are seen more often in males. they are caused by failure of the counterclockwise rotation of the prearterial segment of the embryonic midgut in weeks to of embryonic development. paraduodenal hernias usually present with chronic intermittent abdominal pain, weight loss, nausea, and vomiting. they may present acutely with symptoms of bowel obstruction. peritoneal signs are often not appreciated due to retroperitoneal position of the hernia. ct scan of the abdomen often shows clustering of bowel loops, which cannot be displaced on repositioning the patient. if imaging is equivocal, diagnostic laparoscopy may be undertaken. surgical correction consists of reducing the bowel, resecting nonviable segments, and either closing the defect or opening the sac laterally into the general peritoneal cavity. in summary, paraduodenal hernias are a rare cause of bowel obstruction and as such present a challenge in diagnosis and early intervention. diverticulosis of the appendix is a rare disease found in . - . % of appendectomies, first described in . the clinical presentation may be acute inflammatory with or without appendicitis or it may be an incidental finding in an uninflamed appendix. the congenital type is rare and it has all the bowel wall layers. it most frequently represents as pseudo diverticulum which lacks the muscularis layer. the pathogenesis of appendiceal diverticula is not completely elucidated. its symptoms are similar to and often misdiagnosed for that early acute or chronic appendicitis. while appendectomy is curative for both entities, it is important to distinguish diverticulum of the appendix from appendicitis as it is four times more likely to perforate and may be a sign of an underlying neoplasm. we reported a very rare giant pseudo diverticulum of the appendix in a -year-old male presenting with chronic abdominal discomfort for months. abdominal x-ray showed abnormal gaseous finding. physical exam was significant for a soft rubbery mass in the periumbilical region. blood work revealed slight elevation of c-reactive protein. preoperative ct and mri showed a -centimeter-large cavity composed of thin wall, located at the tip of the appendix with peri appendicular fat stranding. in the concern of pending obstructive symptom and chronic abdominal pain, we decided to perform the resection laparoscopic. the soft mass arose from the tip of the appendix. there were dense adhesions between the appendix, mesentery, and sigmoid colon. after adhesiohedlysis, laparoscopic appendectomy was performed with endogia. the specimen was extracted through a small incision without spillage. hospital course was uneventful and the patient was discharged on post-operative day . the pathological finding was consistent with a pseudo diverticulum of the appendix which lacked muscularis layer and the inner wall of the cavity was lined with a scattered cubital epithelial layer in the continuity with the appendiceal mucosal membrane. here we report a successful laparoscopic resection of an extremely rare giant chronic pseudo diverticulum of the appendix. yvette farran, ms, jorge a miranda, ms, benjamin clapp, md, elizabeth de la rosa, md; texas tech university health sciences center introduction: sigmoid colon intussusception is rarely encountered and given its vague symptomatology diagnosis and management can be difficult. the treatment of an intussusception in adults is different than in children. lipomas as the causative etiology for intussusception are encountered up to . % of the times and up to %- % of the patients require surgical resection for treatment. methods: this is a case report about a year old male that presented with two weeks of worsening abdominal pain and distention. physical exam was only pertinent for abdominal pain on light palpation, guarding and moderate distress. ct scan of abdomen and pelvis demonstrated a lipomatous mass causing complete obstruction of the sigmoid colon with intussusception. this was managed with laparoscopic sigmoidectomy. the patient had an uncomplicated post-operative period and was discharged on post-operative day . pathology of the lipomatous mass confirmed a benign lipoma. discussion: intussusception is rarely encountered in clinical practice in adults and constitutes % of all cases. lipoma induced sigmoid intussusception with complete obstruction is rare. symptoms can be non-specific as in this case. this case report highlights the importance of timely diagnosis and treatment of an intussusception in adult patients. ct scan is the gold standard for diagnosis and often shows a "target sign". other imaging techniques like ultrasound have shown adequate results but remain less effective than ct scan. the treatment in adults is not a reduction by enema like in pediatrics but rather resection of the lead point. this can be appropriately done with a laparoscopic technique in most cases. conclusion: colonic intussusception is rare. surgery is the only treatment for an intussusception in adults since the lead point needs to be removed, and can be attempted safely with a laparoscopic approach. surg endosc ( ) :s -s joshua smith, md, kern brittany, md, amie hop, md, amy banks-venegoni, md; spectrum health case report: year-old female with no significant past medical history presents with a -year history of nocturnal cough that had worsened over the past months and had associated regurgitation. she underwent esophagogastroduodenoscopy (egd) that showed a tortuous esophagus and tight lower esophageal sphincter that required dilation. she received an upper gastrointestinal (ugi) contrast study that showed a dilated, tortuous esophagus with 'bird's beak' tapering, consistent with achalasia, as well as a large epiphrenic diverticulum measuring cm. esophageal manometry confirmed "pan-esophageal pressurization" consistent with type ii achalasia. given her symptoms in the presence of these findings, she elected to proceed with surgery. she underwent laparoscopic, trans-hiatal epiphrenic diverticulectomy, heller myotomy and dorr fundoplication. extensive dissection allowed for approximately cm of retraction down from the chest and we were able to come across it with a single blue load of a mm linear cutting stapler. post-operatively, she tolerated the procedure well with immediate improvement in her symptoms. her ugi on post-operative day showed no evidence of leak, she tolerated a soft diet and was discharged home. she was seen at -week and -year follow-up appointments with complete resolution of symptoms. discussion: epiphrenic diverticula in the presence of achalasia has an occurrence rate of %. large diverticula ([ cm), are even more rare with only a handful of case reports in the literature. historically, thoracotomy or, more recently, thoracoscopic approaches are required for resection. however, thoracic approaches are associated with a % increase in morbidity, namely due to staple line leak and the resulting pulmonary complications. only a single case report exists on our review of the literature that demonstrates successful trans-hiatal laparoscopic resection without post-operative complications of a diverticulum of this size. the shortest documented length of hospital stay postoperatively for similar cases is days, while the average is - days or longer for those with complications. our patient was able to go home on post-operative day after a normal ugi and was tolerating a soft diet. not only does this case show that a large epiphrenic diverticulm can be successfully resected via the trans-abdominal laparoscopic approach, this case makes the argument that patients undergoing any minimally-invasive epiphrenic diverticulectomy and myotomy, with or without fundoplication, may be successfully managed with early post-operative contrast studies and dietary advancement, thus decreasing their length of hospitalization and overall cost of treatment. kazuma sato, shunji kinuta, koichi takiguchi, naoyuki hanari, naoki koshiishi; takeda general hospital background: situs inversus totalis (sit) is a rare congenital condition in which the abdominal and thoracic organs are located opposite to their normal positions. few cases of laparoscopic surgery for gastric cancer with sit have been reported. we report a case of laparoscopic distal gastrectomy with d lymph node dissection performed for gastric cancer in a patient with sit. case description: an -year-old woman was admitted to our hospital for treatment of gastric cancer that was diagnosed by esophagogastroduodenoscopy (egd) at a local clinic after she experienced anemia and nausea. egd identified an irregularly shaped gastric ulcer located at the anterior side of the lesser curvature of the antrum. a biopsy revealed a moderately differentiated adenocarcinoma. she was then diagnosed with sit by chest radiography and abdominal computed tomography (ct). the abdominal ct showed that all organs were inversely positioned and that the wall of the antrum had thickened; it also showed the lymph nodes in the lesser curvature of the stomach, without distant metastasis or an abnormal course of vascularity. the patient was clinically diagnosed with t n m stage iiia gastric cancer according to the japanese classification of gastric carcinoma. a laparoscopic distal gastrectomy with d lymph node dissection in accordance with the japanese gastric cancer treatment guidelines as well as a roux-en-y anastomosis due to an esophageal hiatal hernia were performed. the surgery was safely and successfully performed, although it required more time than usual because the inverted anatomic structures were repeatedly examined during the surgery. the postoperative course was positive, and the patient was discharged on postoperative day without any complications. the final stage of this case was pt bn m stage ia. currently, the patient is doing well without recurrent gastric cancer. conclusion: gastric cancer with sit is an extremely rare occurrence. we experienced a case of laparoscopic distal gastrectomy with d lymph node dissection performed for gastric cancer in a patient with sit. we simulated the operation for sit by viewing left-right reversed ordinary surgical videos. the abdominal ct angiography with a three-dimensional reconstruction helped reveal any variation and confirmed the structures and locations of vessels before the surgery. the operation could safely be performed following the standardized surgical technique by reversing the surgeon standing position and trocar position. sternum or chest wall resection is performed for a variety of conditions such as primary and secondary tumors of the chest wall or the sternum. sternum reconstruction has been a complex problem in the past due to intraoperative technical difficulties, surgical complications, and respiratory failure caused by the chest wall instability and paradoxical respiratory movements. advances in the fields of surgery and anesthesia result in more aggressive resections. nowadays neither the size nor the position of the chest wall defect limits surgical management, because resection and reconstruction are performed in a single operation that provides immediate chest wall stability. chest wall resection involves resection of the ribs, sternum, costal cartilages and the accompanying soft tissues and the reconstruction strategy depends on the site and extent of the resected chest wall defect. here i'll present, the youngest ever case reported, years old girl with rhabdomyosarcoma involving the sternum. i will present the management challenges and the reconstruction options. introduction: neuroendrocrine malignancies constitute . % of all cancers. the gastrointestinal tract is the commonest site, followed by the lung. the last decade has seen a steady increase in their incidence. this is a case series of twenty five such tumours and their clinicopathological characteristics. materials and methods: twenty five patients with neuroendocrine tumours of the gastrointestinal tract were studied with reference to their demographic and clinicopathological characteristics. apart from routine pathological examination, these tumours were also checked for e cadherin expression as an independent marker of aggressive disease. results: the age of our patients ranged from to years. we had female and male patients, contradicting a female preponderance in literature. the vast majority of the tumours we encountered were from the stomach and duodenum, with and patients, respectively. two tumours were at the gastroduodenal junction, two from the appendix, small intestine and pancreas, each, and one each from the rectum and gall bladder. this is in contrast to literature that shows that neuroendocrine tumours of the git most commonly arise from the appendix and small bowel, followed by the rectum, stomach and duodenum. two of these tumours were functional. the diagnosis was confirmed by immunohistochemistry staining for chromogranin a and synaptophysin. grading was done using who criteria that takes into account the mitotic count, ki index and necrosis. of our cases were grade i. further, immunohistochemistry for e cadherin showed that absence of expression correlated with more aggressive clinical behavior. out of twenty five patients were operable at presentation and standard resections depending on the organ of origin with adjuvant therapies were given as required. could only be given palliative care. the functional tumours were treated with radiolabelled somatostatin analogues following uptake studies. conclusion: as neuroendocrine tumours are relatively rare, information about them is not as abundant as with other malignancies. absence of e cadherin expression is associated with more aggressive disease. more studies are required that document the pathological characteristics and clinical behavior in order to offer well rounded treatment protocols that treat not only the primary, but also the generalized effects of the secretions produced by them. targeted chemotherapy is gaining prominence, but more specific drugs directed at the plethora of receptors these tumours express, could potentially revolutionize treatment. ( ) . unfortunately there are no publications from denmark. we would like to present first to our knowledge reported case of double gallbladder in denmark. double gallbladder is a rare anomaly with a prevalence of : in autopsy studies, described first by boyden in ( ) . there are several classifications of double gallbladder that are based on relation between gallbladder, cystic duct and common bile duct ( , ) . non-specific symptoms and inadequate imaging are possible causes of lack of awareness of the condition. removal of all gallbladders, preferably laparoscopic with special attention to the biliary anatomy, is recommended ( ). method: case report with review of the literature. a -year-old female patient of polish origin was hospitalized due to upper right quadrant pain. on admission clinical manifestations and paraclinical abnormalities of pancreatitis were present. ultrasound scanning of the abdomen showed bile stones, ultrasonic manifestations of acute cholecystitis and normal intra-and extrahepatic bile ducts. because of elevated liver enzymes mrcp was performed and showed double gallbladder, double cystic duct and signs of pancreas anulare. scheduled ercp confirmed bile stones in cbd, double gallbladder with double cystic duct, h-type according to harlaftis classification ( ) . because of minor retroperitoneal perforation second ercp was needed for removal of all stones. the patient was then scheduled to laparoscopic cholecystectomy with perioperativ cholangiography. conclusion: anatomical variations of the gallbladder such as double gallbladder are rare and often remain unnoticed. they are most often identified because of clinical manifestations symptoms, diverse imaging studies, during surgery or autopsy. as most of them are not expected, they can contribute to complications during surgery. careful preoperative imaging is very important to prevent accidental bile duct injury. looking at the number of case reports, double gallbladder seems to be slightly more common than expected. the interesting question is whether a gallbladder discovered during an unrelated radiological investigation in a patient that previously underwent a cholecystectomy can represent undetected case of double gallbladder. we would like to present a review of the literature as well as images from mrcp, ercp and laparoscopy. michael jaroncyzk, md, courtney e collins, md, ms, vladimir p daoud, md, ms, ibrahim daoud, md; st. francis hospital; hartford ct introduction: several decades ago, surgical training was saturated with procedures to treated peptic ulcer disease. since the introduction of histamine- blockers and proton pump inhibitors, these procedures have dwindled significantly. however, there are still instances where patients require surgical intervention for peptic ulcer disease. perforation is one of the indications for surgery. the surgical options to treat a perforated peptic ulcer are numerous. one of the most common options is a graham patch. we are presenting a case of a patient with a perforated ulcer that did not have available omentum for the repair. methods and procedures: recently, a -year-old female with a past history of an open total abdominal hysterectomy and bilateral salpingo-oophorectomy presented as an outpatient with chronic lower abdominal pain. she underwent a work-up and imaging that did not reveal any pathology. at diagnostic laparoscopy, she had diffuse lower abdominal adhesions, which were lysed. she was discharged on the same day, but presented to the emergency department two days later with severe abdominal pain and fevers. the work-up revealed tachycardia, diffuse abdominal tenderness with peritoneal signs, leukocytosis and a large amount of free air on imaging. she was emergently brought to the operating room for a diagnostic laparoscopy. during laparoscopic exploration, the lower abdominal cavity appeared normal for a recent lysis of adhesions. attention was turned to the upper cavity to find the pathology. bile-stained free fluid and peri-gastric exudates were identified, but no perforation was visualized. intra-operative endoscopy revealed the site of perforation in the antrum on the lesser curvature. a biopsy was performed and the decision was made to perform a graham patch. however, the omentum was already densely involved with the lower abdominal cavity from the enterolysis. due to the close proximity of the falciform ligament, it was mobilized laparoscopically and the pedicle was used as a graham patch. the patient recovered without any additional issues. the biopsy was reported as a chronic gastric ulcer. conclusion: surgical history has given us many options to treat peptic ulcer disease that are not nearly as common as they were decades ago. perforated ulcers can be managed laparoscopically and graham patches are a common choice for repair. however, the lack of the omentum for a proper pedicle flap can pose a problem in some patients. we have shown in this patient that a falciform pedicle flap can be successfully used as a substitution. laparoscopic management of boerhaave's syndrome after a late presentation: a case report and literature review tahir yunus, hager aref, obadah alhallaq; imc background: boerhaave's syndrome involves an abrupt elevation in the intraluminal pressure of the oesophagus, causing a transmural perforation. it is associated with high morbidity and mortality. having a nonspecific presentation may contribute to a delay in diagnosis and results in poor outcomes. treatment is challenging, yet early surgical intervention is the most important prognostic factor. case presentation: we present a case of a thirty-two-year-old male with a long medical history of dysphagia due to benign oesophagal stricture. he presented with acute onset of epigastric pain after severe emesis. based on computed tomography scan, he was diagnosed with boerhaave's syndrome. presenting with signs of shock, mandated immediate surgical exploration. for which he was taken for laparoscopic primary repair with uneventful postoperative recovery. the golden period of the first hours of insult still applies for cases of oesophagal perforation. the rarity of these cases makes a comparison between the various treatment methods difficult. our data support that the use of laparoscopic operative intervention with primary repair as the mainstay of treatment for the management of oesophageal perforation. lipomas of the gastrointestinal tract are rare benign soft tissue tumors that are often discovered incidentally. these lesions are often asymptomatic, but have occasionally been reported to have clinical significance as will be described in this case report. a year old male initially presented to his primary care physician's office with a three week history of vague intermittent abdominal pain. his pain was located in the mid epigastrium and was associated with mild nausea. past medical history was significant for hyperlipidemia and a right-sided goiter, and he denied any previous surgeries. outpatient work up revealed a microcytic anemia, intermittent melena and hemoccult positive stools. the patient was referred to hematology and gastroenterology. endoscopies revealed gastritis, and small internal and external hemorrhoids. he underwent an outpatient ct scan which demonstrated a . . cm mass within the lumen of the jejunum causing long segment non-obstucting intussusception. subsequently, the patient was referred to surgery and underwent a diagnostic laparoscopy. at the time of surgery, an approximately twelve centimeter segment of proximal jejunum was identified intussuscepting into a distal limb. this segment was attempted to be reduced laparoscopically, however there was significant mesentery within in the intussusceptum and the segment could not be safely reduced. therefore, the section of bowel was delivered through a small periumbilical incision. the intussusceptum was then able to be manually reduced from the intussusception. at this point a large mass was palpated inside the lumen of the jejunum. a small bowel side to side, functional end to end resection and anastomosis was preformed. the bowel was returned to the abdomen and the abdomen was re-insufflated. the remainder of the small bowel was run and no additional lesions were identified. final pathology revealed a . . . cm submucosal partially obstructing lipoma with ulceration at the tip. the patient recovered uneventfully and was discharged home on the second post operative day. this case report describes a submucosal jejunal lipoma that was acting as a lead point for intermittent non-obstructing small bowel intussusception, while simultaneously causing a microcytic anemia due to ulceration at the tip of the lipoma. laparoscopic assisted reduction and small bowel resection is a safe and effective treatment for gastrointestinal tract lipomas that are unable to removed endoscopically. percutaneous endoscopic gastrostomy (peg) is an alternative to laparotomy for open gastrostomy tube placement to provide enteral nutrition for those who are unable to pass nutrition orally. despite being less invasive, the procedure is not without its complications, one of which includes the formation of a gastrocolocutaneous fistula. the case describes a year old female who presented with a peg placed months prior with reports of leakage of tube feeds from the gastrostomy site. as there was concern for possible ileus or obstruction, an upper gi series was completed which seemed to indicate dislodgement of the g-tube. the g-tube was replaced and a follow-up gastrograffin study was repeated which now indicated that the g-tube was within the lumen of the colon. soon thereafter fecal matter was noted to be draining around the g-tube site; however, patient was without clinical signs of peritonitis. the patient was managed non-surgically as she was a poor surgical candidate with multiple prohibitive co-morbidities. the g-tube was removed bedside by cutting it flush at the skin level with the anticipation that the remainder of the tube would be excreted with bowel movements. the decision was then made to attempt closure of the gastric fistula endoscopically which was accomplished with hemoclips. a follow up upper gi study hours later showed no extravasation of contrast through the gastric fistula. the colocutaneous fistula had self-resolved over the next couple days as well. placement of the peg tube through the transverse colon can present with varying ill effects including diarrhea, pneumoperitoneum, peritonitis, gram negative pulmonary infection or feculent vomiting with the formation of a gastrocutaneous fistula. treatment historically for a gastrocolocutaneous fistula has been exploration and excision of the fistula tract with resection of the involved colonic segment. however, there currently is no gold standard for the management of, and really ranges from conservative management to surgical and is dependent on the presenting symptoms. if the peg becomes dislodged with resultant spillage from the colon with resultant peritonitis, surgical exploration is needed with removal of the g-tube and repair of the stomach and colon. on the other hand, non-surgical management has been suggested in management of a well-established fistula. fistula closure may be spontaneous; however, can be inhibited due to delayed gastric emptying or leakage of gastric secretions through the fistula. endoscopic clipping of the fistula tract employing the hemoclips is a treatment option. median arcuate ligament syndrome (mals) is a rare etiology of abdominal pain caused by narrowing of the celiac artery at its origin by the median arcuate ligament with relative hypoperfusion downstream. patients suffer from post-prandial abdominal pain, abdominal pain associated with exercise, nausea, and unintentional weight loss. diagnosis is historically made by demonstrating elevated celiac artery velocities and respiratory variation on dynamic vascular studies. standard of care for mals patients is laparoscopic celiac artery dissection with release of the median arcuate ligament. at our institution, we have encountered fourteen patients (eleven female, three male) diagnosed by elevated peak velocity in the celiac artery by duplex ultrasound in conjunction with ct angiogram, mr angiogram, arteriogram, or multiple modalities. all but one patient had multiple diagnostic imaging modalities, with the most common being ct angiogram; eight patients had invasive imaging. the mean age at presentation was . years in men and . years in women. on average, male patients presented with a longer duration of symptoms, . years (range - years), as compared to women, . years (range - years). symptoms were fairly consistent between genders and included nausea, emesis, abnormal bowel habits, early satiety, post-prandial pain, and weight loss. all male patients reported at least two symptoms, most commonly nausea and post-prandial pain. in female patients, % reported having three or more symptoms. notably, post-prandial pain was universal among men and women, while weight loss was exclusive to female patients as reported by %. pre-operative peak velocities were recorded in all but one patient, with mean values more elevated in female patients as opposed to male patients, cm/s versus cm/s. post-operative duplexes were obtained in seven patients; pooled data show a mean change of negative cm/s for an average of cm/s after decompression. in all cases, the celiac artery trifurcation was visualized and noted to have a distinct change in artery caliber after division of the ligament. in total, % of patients reported significant improvement with return to normal diet and healthy weight gain post-operatively. of the three without complete resolution, two were diagnosed with motility disorders and one was lost to follow-up. our experience demonstrates that laparoscopic release of the median arcuate ligament in patients with significant flow limitation of the celiac artery on dynamic and anatomic imaging can be a successful treatment option for patients with recalcitrant pain and gastrointestinal dysfunction with no alternative diagnosis. matthew a goldstein, ma, kirill zakharov, do, sharique nazir, md; nyu langone brooklyn adhesions are fibrotic bands that form between and among abdominal organs. the most common cause of abdominal adhesions is previous surgery in the area as well as radiation, infection and frequently occurring with unknown etiology. these bands occur among abdominal organs, commonly the small bowel, and can lead to obstruction or remain asymptomatic, akin to the patient discussed here. congenital abdominal adhesions are rare and have received little attention in research and field of study. the patient described in this case is a -year-old female with a past medical history of morbid obesity, bmi of , hypertension and no past abdominal surgical procedures. the patient presented in august for bariatric surgical consultation and was ultimately taken for an attempted laparoscopic sleeve gastrectomy. upon entering the abdomen, significant adhesions were encountered and an additional attending was called to assist in identifying the stomach. the splenic flexure was found to be plastered to the diaphragm and the descending and transverse colon were adhered to the anterior surface of the stomach. additionally, small bowel adhesions encased the area between the right and left hepatic lobes as well as the caudate lobe. after extensive enterolysis, the pylorus remained the only identifiable portion of the stomach. the patient also demonstrated significant hepatomegaly and a wedge resection was performed. the amount of adhesion and matting of the small and large bowel obscured the view of the stomach and the procedure was deemed too dangerous and terminated. this case represents the uncommon scenario in which an abdomen with no prior surgical history presents with extensive, obscuring adhesions. one such recent study describes the influence of cytokines and proinflammatory states as contributors to obstruction and malrotation in children, but this patient demonstrated no significant history. further investigation is needed to determine potential etiologies of symptomatic and non-symptomatic congenital adhesions among bariatric patients who fail conservative treatment. today the patient is doing well and the surgical team will attempt to complete the procedure in the coming months. laparoscopic spenulectomy: an interesting case report riva das, md , daniel a ringold, md , thai q vu, md ; orlando health, abington jefferson health introduction: spenules, or accessory spleens, are a rare disease entity. most often, they are asymptomatic, and found incidentally during radiographic workup for an unrelated problem. torsion can cause a splenule to not only become symptomatic, but also confound the results of usual diagnostic studies. case description: a -year-old female patient with history of uncomplicated hypertension, hyperlipidemia, hysterectomy, cholecystectomy, spinal surgery, and partial left nephrectomy, presented to the hospital with a two-week history of intermittent left upper quadrant abdominal pain. she denied any similar episodes in the past, or any associated symptoms. further investigation with a ct scan of the abdomen and pelvis showed an acute inflammatory process in the left upper quadrant in same location as some colonic diverticulosis, as well as a . cm soft tissue mass. this indeterminate soft tissue mass was described as having decreased attenuation compared with the spleen. differential diagnosis for this mass included malignancy, an atypical splenule, or an infectious/inflammatory mass. an mri was recommended for further evaluation, but did not reveal any additional significant findings. nuclear medicine liver/spleen scintigraphy was performed, which showed no focal activity associated with the indeterminate left upper quadrant mass, therefore making it unlikely to reflect a splenule, and making malignancy the diagnosis of exclusion. following a period of observation with analgesia, intravenous antibiotics, and bowel rest, her abdominal pain did not resolve, and the decision was made to proceed with operative exploration. diagnostic laparoscopy revealed an approximately cm spherical mass in the left upper quadrant located just below the inferior aspect of the spleen. the superior aspect of the mass gave rise to a vascular pedicle, which upon tracing, seemed to originate from the splenic hilum. this pedicle was easily ligated, and the mass removed. pathology revealed an extensive infarcted hemorrhagic nodule with organizing thrombus and attached thrombosed artery, consistent with an infarcted splenule due to torsion along its own axis. the patient had an uncomplicated postoperative course. discussion: this case report demonstrates the unusual presentation and workup of a patient that was ultimately diagnosed with an infarcted splenule, despite imaging findings that did not correlate, and may even have confused her diagnosis. scintigraphy, which is normally the gold standard for diagnosing and localizing accessory splenic tissue, was in this case unrevealing, due to inability of the tracer to traverse the torsed vascular pedicle. operative exploration was both diagnostic and therapeutic. patients which was treated with antibiotics suggested by culture and sensitivity report and local wound care. one patient died due to sepsis at presentation. conclusion: chikungunya virus was found circulating in rodents in pakistan as early as . duodenal ulcer perforation which is a common surgical emergency in our part of the world usually presents with pinpoint perforation in ant wall of first part of duodenum unlike in already diagnosed cases of chikungunya disease where a slit like duodenal perforation is noted in the anterior wall of first part of duodenum. literature and consensus relate this perforation with the excessive use of nsaids due to usual presentation of arthritis in chikungunya disease but the unusual presentation is still to be answered. introduction: bouveret's syndrome is a rare form of gallstone ileus in which an impaction of a gallstone in the duodenum results in a gastric outlet obstruction. gallstone ileus accounts for approximately - % of all cases of small bowel obstruction. the terminal ileum is the most common location for a calculus to cause obstruction followed by the proximal ileum, jejunum and duodenum/stomach respectively. open and laparoscopic surgery has previously been the mainstay of treatment for bouveret's syndrome, however with the advent of new endoscopic techniques and instruments there has been increasing success in endoscopic management. this case report looks at a patient with a gastric outlet obstruction from a gallstone, and discusses the current literature regarding diagnosis and management. case: year old male presented with several day history of epigastric abdominal pain and multiple episodes of nonbloody, nonbilious emesis. he had previously been diagnosed with cholelithiasis, however had refused surgery at that time. on admission the patient was found to have a leukocytosis of . . an ultrasound was performed in which the images were limited due to pneumobilia. a subsequent ct scan revealed pneumobilia, and a large cm gallstone impacted in the first portion of the duodenum causing a gastric outlet obstruction. the patient underwent failed endoscopic attempts at removal and ultimately required a laparotomy, enerotomy with stone extraction. discussion: bouveret's syndrome is a rare variant of gallstone ileus. with newer endoscopic techniques and electrohydraulic lithotripsy, there has been increasing success with endoscopic retrieval of the impacted gallstones. there is some controversy in regards to the need for definitive operative management. stone extraction, without cholecystectomy and fistula repair, has been shown to have less postoperative complications as well as lower mortality rates compared to when a cholecystectomy and fistula repair has been performed. total mesorectal excision (tme) with neoadjuvant chemoradiotherapy (nacrt) is standard treatment for rectal cancer, which has resulted in a decrease in local recurrence. however, nacrt has shown no significant overall survival and some adverse effects mainly caused by radiation therapy. recently, the usefulness of neoadjuvant chemotherapy (nac) has been reported. we retrospectively assessed the efficacy and safety of the neoadjuvant mfolfoxiri compared with nacrt followed by laparoscopic surgery. a total of patients undergoing laparoscopic surgery for lower rectal cancer (clinical stage: ii or iii) from july to february in our department were retrospectively evaluated. patients underwent nac, and patients underwent nacrt. the following data were collected: pathological complete response (pcr), histological grade, down staging, radial margin (rm) and postoperative complications. histological grade was defined as follows: tumor cell necrosis or degeneration is present in less than one third of the tumor area (grade a), between one and two thirds (grade b), more than two thirds but viable cells remain (grade ), and complete response (grade ). these two groups were demographically comparable. down staging did not differ between the two groups. histological grade (?grade b) and pcr were significantly higher in the nacrt than in the nac group (p. ). rm had no significant difference in both groups, but tended to be able to secure negative rm in the nac group ( % vs. . %, p= . aims: increasing evidence suggest that cme may improve overall and disease free survival in colon cancer. our aims were to investigate the safety and efficacy of single incision laparoscopic cme colectomy (silcc) compared to multiport cme laparoscopic colectomy (mpclc) providing the first meta-analytical evidence. methods: pubmed, scopus and cochrane library were searched. studies comparing the silcc to mpclc in adults with colon adenocarcinoma were included. the studies were critically appraised using the newcastle ottawa scale. statistical heterogeneity was assessed with x and i . the symmetry of funnel plots was examined for publication bias. results: one randomized and four case control trials were included ( silcc vs sl introduction: obesity has been associated with increased morbidity following total proctocolectomies with ilealpouch anal anastomosis (tpc-ipaa). however, the incremental added risk of increasing obesity class is not known. the aim of this study was to evaluate the additional morbidity of increasing obesity class for tpc-ipaa. methods: after ethics board approval, the acs-nsqip database ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) was accessed to identify patients who underwent elective tpc-ipaa. body mass index (bmi, kg/m ) was classified as normal ( . - . ) , overweight ( . - . ), obesity class-i ( - . ), obesity class-ii ( - . ) and obesity class-iii (≥ ). primary outcomes were overall surgical site infection (ssi) and organ-space infection (osi). secondary outcomes were -day major morbidity and length of hospital stay (los aim: in curatively intended resection of sigmoid and rectal cancer, many surgeons prefer to perform ligation of the root of the inferior mesenteric artery (ima), high tie, because of oncological reasons. however, ligation of the ima has been known to decrease blood flow to the anastomosis. there are few reports of patients undergoing the reduced port laparoscopic approach (rps) including single-incision laparoscopic approach (sils) even among those undergoing laparoscopic lymph node dissection around the ima with preservation of the left colic artery (lca). our objective was to evaluate the quality of this procedure regarding application of rps for the treatment of sigmoid and rectal cancer. methods: the feasibility of this procedure was evaluated in consecutive cases of rps for sigmoid and rectal cancer. a lap protector (lp) was inserted through a . cm transumbilical incision, and an ez-access was mounted to lp and three -mm ports were placed. almost all procedures were performed with standard laparoscopic instruments using a flexible scope (sils). a mm port was inserted in right lower quadrant mainly in rectal cancer surgery (sils + ). our method involves peeling off the vascular sheath from the ima and dissection of the ln around the ima together with the sheath. results: lymph nodes around the ima were dissected with preservation of the lca in cases (group a). the ima was ligated at its root in cases (high tie, group b). in group a, patients were treated with sils and patients were treated with sils+ . in group b, patients were treated with sils and patients were treated with sils+ . median operative time was . , and . min for group a, and b, respectively. the operative time was significantly longer in group a. estimated blood loss was . and . g, and mean numbers of harvested ln were . , and . . none of the other operative results of groups a and b were different statistically. in this series, there was only one anastomotic leakage in group b. conclusion: our method allows equivalent laparoscopic lymph node dissection to the high tie technique. the operative time tends to be longer, however this procedure has a possibility to reduce an anastomotic leakage. introduction: the routine mobilization of the left colonic flexure in colorectal surgery is still a matter of debate. we present our surgical approach with data. this technique may increases the surgical expertise/confidence when the surgical maneuver is necessary. up to % of all splenectomies are for surgery-related injuries; % of those splenic injuries are treated by splenectomy. the iatrogenic splenic injury rate during colorectal surgery is . %. iatrogenic splenic injuries create: increased risk of mortality/morbidity, extended operative time/patient in-hospital stay and increased healthcare costs. risk factors for iatrogenic splenic injury are: advanced age, adhesions, underlying pathology. obesity is not a risk factor. it is debated if the left colonic flexure mobilization is a risk factor for splenic injury. the ligament over-traction is the most frequent damage mechanism. the most dangerous surgical manuever is the spleno-colic ligament surgical dissection. moreover, laparoscopy descreases by almost , times the splenic injury risk. some surgeons are reluctant to routinely take down the splenic flexure. materials and procedures: robotic left colonic/rectal cases with routine splenic flexure mobilization technique have been performed: left colectomy (n= ), rectal surgery (n= ), transverse-colectomy (n= ) and pancolectomy (n = ). conversion rate , %, ebl\ ml, postop-leak ( . %) and % iatrogenic splenic injuries. results: in our approach, there are pathways that need to be mastered for the splenic flexure mobilization:a) medial to lateral dissection (underneath the inferior mesenteric vein); b) lateral to medial (from the lateral peritoneal reflection); c) access to the lesser sac with omental detachment from the transverse colon; d) access to the lesser sac with the gastrocolic opening, following the inferior border of the pancreas. the dissection should be closer to the colon rather than to the spleen. in our experience the routine mobilization of the splenic flexure may have some advantages: a) better (without tension) distal anastomosis formation; b) better perfusion of the proxiaml stump; c) wider oncological dissection; d) no need of going back to the flexure when the proximal stump is too short; e) mastering a surgical manuver useful in other procedures (e.g. distal pancreasectomy). the theoretical drawbacks of routine splenic flexure mobilization can be:a) longer operative time, which is on average increased by minutes; b) risk of splenic injuries, in our experience, no splenic injuries have been registered. conclusions: technical accuracy with cautious dissection/visualization can reduce iatrogenic splenic damages rate. laparoscopy decreases splenic injury rate. robotic surgery may have the potential to further reduce this complications. our data suggest that the routine mobilization of the splenic flexure, has more advantages than drawbacks and it can reduce the iatrogenic splenic injury rate. more trials are needed in order confirm our findings. introduction: the robotic stapler with the endowrist™ technology (intuitive surgical, inc.) includes a larger range of motion and articulation compared to the laparoscopic device, and may provide some benefits in difficult areas like the pelvis. to date, few studies have been published on the application of robotic endowristed stapling. we present our preliminary experience using the robotic stapler in low anterior rectal resection (larr) with total mesorectal excision (tme) for rectal cancer. methods and procedures: between march and september , patients underwent elective robotic larr with tme and primary colorectal anastomosis within the eras program. patient demographic, intra-operative data and post-operative outcomes were compared between the endowrist™ robotic stapler group (rs group) and the laparoscopic stapler group (ls group). results: the two groups were homogeneous in terms of demographic and clinical characteristics. thirteen ( males) and patients ( males) were included in rs and in ls group, respectively. seven patients received preoperative chemoradiation in rs group, in ls group. there was no difference in intra-operative blood loss and total operative time. the median number of stapler fires for patients in rs group and in ls group was (range, - ) and (range, - ), respectively. loop-ileostomy was fashioned in patients in rs group ( . %) and patients in ls group ( . %). the days mortality was nil. two cases of anastomotic leaks have been detected in rs group ( . %), cases ( . %), occurred in ls group, all treated conservatively. the mean length of postoperative stay was . ± . days in rs group, . ± . days in ls group. conclusions: in our preliminary experience the application of robotic stapler during larr with tme has shown to be safe and feasible with acceptable morbidity. even if our case series is pretty small, fewer stapler fires were required in the rsg compared to lsg. we believe that the robotic stapler might lead to a more precise firing during pelvic surgery: it can explain the trend toward a decreased number of fires, that has been well documented in literature to be related to a lower risk of anastomotic leak. further high quality studies are required to confirm these findings. background and objectives: the present study was aimed at investigating the safety and feasibility of laparoscopic ultra-low anterior resection (l-ular) with total mesorectal excision (tme) and transanal specimen extraction for rectal cancer located at lower one-third rectum, and specifically understanding the oncological outcome of the operation. patients and method: a prospective designed database of a consecutive series of patients undergoing laparoscopic ultra-low anterior resection for rectal malignancy with various tumornode-metastasis (tnm) classifications from to at the texas endosurgery institute was analyzed. in this study ultra-low anterior resection is defined as low anterior resection for the malignant lesion at distal / of rectum. results: ultralow anterior resections were completed laparoscopically with tme and transanal specimen extraction. the operating time for the surgery was . ± . minutes, and estimated blood loss during the procedure was . ± . ml. the length of the lesion from the anal verge measured with intraoperative colonoscopy ranged from . cm to . cm, and shortest distance of colorectal anastomosis from the anal verge is cm. since diverting ileostomy was routinely installed after l-ular, none was found to have anastomotic leakage, however patients developed anal stenosis within -month follow-up. therefore the overall rate of postoperative complication is . %. moreover patients were reported to have local recurrence in -year followup with the rate of . %. conclusions: l-ular is safe and effective procedure for the rectal cancer at distal / rectum with comparable local recurrence and postoperative complication rates, thereby suggesting l-ular can be considered as a procedure of choice for rectal cancer at very low location in the rectum. for rectal cancer, however, local full-thickness excisions are fraught with high local recurrence rates -even if limited to early and best selected lesions. this corroborated observation is likely caused by a combination of missed nodal disease and direct implantation of tumor cells into the mesorectum, which upstages even early t lesions to at least a t lesion. the treatment of choice for invasive adenocarcinoma consists of an oncological total mesorectal resection, possibly with other modalities. rectal tumors of uncertain behavior can present a treatment dilemma between over-treatment vs under-treatment. concept: if the nature of a lesion is not certain or if contradictory results have been obtained, we propose a superficial local excision as a mucosal excisional biopsy to establish the diagnosis while avoiding interference with subsequent definitive treatment modalities by preserving the integrity of the external rectal wall and mesorectum. a benign final pathology concludes the treatment, whereas a detection of invasive cancer will be managed with a subsequent oncological resection. methods: this is a case report of a -year-old woman found to have a . cm villous lesion in the mid to distal rectum without proven or disproven invasive cancer. a tems-guided mucosal resection of the rectal mass at cm above the anal verge was performed whereby the lesion was dissected off the underlying muscularis. results: with preoperative discrepant erus and mri staging ut - vs ct lesion, a technically successful mucosal resection of the large rectal mass was carried out. pathology revealed a tubulovillous adenoma without high grade dysplasia or malignancy and a complete resection. conclusion: tems mucosal excisional biopsy of rectal tumors of uncertain behavior allows for a less invasive diagnostic approach that may (a) be definitive treatment if the lesion is proven benign, or (b) confirm the need for more aggressive treatment without having burned any treatment bridges or upstaged an early tumor by violating the mesorectal plane. an oncologic resection with appropriate (neo-)adjuvant chemotherapy can be carried out while preventing the potential for tumor seeding at initial operation. background: adequate visualization of the entire lumen of the large bowel is essential in detecting pathology and establishing diagnoses during colonoscopies. patients are provided dietary instructions and medications in order to achieve adequate bowel preparation. given the extensive amount of preparation required, some patients may be unable to adhere to the prescribed routine, resulting in rescheduling or repeat procedures and misallocation of limited resources. a number of previous quality-improvement efforts have been implemented to ensure adequate preparation prior to colonoscopy. objective: the objective of this study was to develop and assess the feasibility of a novel smart phone application in the delivery of bowel preparation instructions. methods: a novel smart phone application was developed to deliver bowel preparation instructions to patients undergoing colonoscopy for the first time. patients were included in the pilot phase of this project if they were undergoing a colonoscopy for the first time. we included patients who had access to a smart phone, had not previously had a bowel preparation for any reason. we excluded patients with a previous diagnosis of inflammatory bowel disease or colorectal cancer. patient surveys were administered at the time of colonoscopy. patients were questioned regarding the completeness of bowel preparation and adherence to bowel preparation instructions. patient questionnaires were completed to ascertain the ease of use of the smart phone application and any concerns that arose. quality of bowel preparation was assessed by the colonoscopist using the validated ottawa bowel preparation score. this is the pilot study results for the "coloprep" trial (nct ). results: a total of patients were enrolled in the pilot phase of this study. patient satisfaction, adherence to instructions and ease of use of the smart phone application were ascertained. bowel preparation, as assessed by the colonoscopist, was reported. conclusions: this study assessed the feasibility of using a novel smart phone application for delivery of bowel preparation instruction. this pilot study is the initial phase of a randomized controlled trial to compare smart phone application vs. written instructions in the delivery of bowel preparation instructions. the . median follow-up was months. there were no statistically significant differences found in clinical features and laboratory findings between the two groups. no statistically significant difference was found regarding the overall success rates and the complication rates between the conservative and the surgical arms (success rates: . % and . % (p= . ) and complication rates: . % and . % (p= . ), respectively). however, surgical treatment was better than conservative treatment in preventing recurrent diverticulitis (recurrence rates: % and . % (p= . ), respectively). conclusion: conservative management with bowel rest and antibiotics is a safe and effective treatment for right-sided colonic uncomplicated diverticulitis and may be considered as the initial option. on the other hand, laparoscopic diverticulectomy is also safe, effective and adequate. surgery is advocated to decrease the recurrence rate. introduction: it has been hypothesized that the structural and functional changes that develop in the defunctioned segment of bowel may contribute to the development of postoperative ileus (poi) after loop ileostomy closure (lic). as such, longer intersurgery interval between ileostomy creation and lic may increase poi. methods and procedures: after institutional review board approval, all patients who underwent lic at a single institution between - were identified. the primary endpoint, primary poi, was defined as either a) being kept nil-per-os on or after postoperative day for symptoms of nausea/vomiting, distension, and/or obstipation or b) having a nasogastric tube (ngt) inserted, without postoperative obstruction or sepsis. secondary endpoints included length of hospital stay (los) and non-poi related morbidity. patients who left the operating room with a ngt, had a planned laparotomy with a concomitant procedure at the time of lic, had a total proctocolectomy as their index operation, or had secondary poi, were excluded. patients were then divided into two groups based on timing from the index operation to lic (\ months vs. objective: fecal incontinence can be a debilitating problem significantly diminishing productivity and quality of life. sacral neuromodulation has emerged as a first line surgical option treatment in patients with fecal incontinence. though its efficacy has been rigorously evaluated in adult populations there is scant data available for its use in the pediatric pateints with fecal incontinence. this case study discusses the management of fecal incontinence in a pediatric patient with a history of hirschsprung's disease utilizing sacral nerve stimulation. methods: our patient is a -year-old female with a history of hirshsprung's diagnosed in infancy and treated surgically with coloanal pull through at the age of who presented with complaints of fecal incontinence. the patient was wearing pads daily, noting frequent uncontrolled bowel movements as well as having frequent missed days of school due to these symptoms. despite maximal medical management and pelvic floor physical therapy the patient continued to have - episodes of fecal incontinence daily. a ct scan with rectal contrast was used to establish her postoperative anatomy. anal manometry showed low rest/squeeze pressures, absent resting anal inhibitory reflex, and abnormal sensation. furthermore, during balloon expulsion testing the patient failed to pass device. the patient was deemed a candidate for stage testing with sacral nerve neuromodulation. during follow-up, the patient was noted to have resolution of her episodes of fecal incontinence and the second stage was completed. the patient continues to note % continence and dramatic improvement in her quality of life. conclusion: in this patient with a history of severe fecal incontinence due to hirschsprung's disease, sacral neuromodulation has had a significant impact on her quality of life. post-operatively she continues to have marked improvement in her symptoms with - bowel movements a day with no recurrence of fecal incontinence. the use of sacral neuromodulation is a promising treatment for fecal incontinence in the pediatric population. future research investigating the longterm efficacy of this treatment modality in the pediatric population is needed. cases of bowel obstruction caused by colorectal cancer recurrence and progression were excluded. surgical cases ( . %) were considered to be early bowel obstruction and ( . %) were classified as late bowel obstruction. left hemicolectomy (n= , . %) was a significantly more frequent procedure in early bowel obstruction, and abdominoperineal resection (n= , . %) was significantly more common in late bowel obstruction (p. ). both early and late bowel obstruction included adhesive small bowel obstruction (n= ), internal hernia (n= ), and strangulation obstruction (n= ). internal hernia (n= ) and strangulation obstruction (n= ) occurred after left hemicolectomy and abdominoperineal resection, respectively. there is no apparent relationship between surgical procedures and adhesion regions (abdominal wall, intestinal tract, and pelvic cavity). the incidence rate of postoperative small bowel obstruction remained low, and laparoscopic colectomy had been safely performed. however, countermeasures are needed because of the high frequency of both early and late bowel obstruction which occurred after left hemicolectomy and abdominoperineal resection, respectively. improved utilization of resources as an improvement introduction: nowadays, treatment decisions about patients with rectal cancer are increasingly made within the context of a multi-disciplinary team (mdt) meeting. the outcomes of rectal cancer patients before and after the era of multi-disciplinary team was analyzed and compared in this paper. the purpose of the present study is to evaluate the value of discussing rectal cancer patients in a multi-disciplinary team. methods and procedures: in our health institute, weekly mdt conferences were initiated in january . meetings were attended by surgeons, radiologists, radiation and medical oncologists and key nursing personnel. all rectal cancer patients diagnosed and treated in - in the general surgery division of the "carlo urbani" hospital in jesi (an, italy) were included. then, the data from rectal cancer patients in were evaluated, before the adoption of mdt and in year , after the adoption of meetings. datasets regarding demographics, tumor stage, treatment, and outcomes based on pathology after operation were obtained. during an mdt discussion patient history, clinical and psychological condition, co-morbidity, modes of work-up, clinical staging, and optimal treatment strategies were discussed. a database was created to include each patient's workup, treatments to date and recommendations by each specialty. ''demographic variables'' consisted of age at diagnosis, sex, body mass index, comorbidities, american society of anesthesiologists physical status classification system, clinical stage and pathological stage. other analyzed variables included baseline carcinoembryonic antigen (cea), the type of imaging, use of neoadjuvant chemo-radiation, restaging following neoadjuvant therapy, distance from the anal verge, operation type and use of adjuvant chemo-radiation. ''outcome variables'' consisted in a comparison for each group between clinical and pathological stage. results: sixty-five patients were included in this study: thirty patients in (pre-mdt) and thirty-five patients in . demographic variables did not differ significantly between groups. preoperative clinical stages with baseline preoperative cea and postoperative pathological stage were analysed, too. thanks to the mdt and the increased use of the neoadjuvant therapy, a statistically significant difference in reduction of the stage between the clinical and pathological stage in the patients of the mdt group was verified. conclusions: the vast majority of rectal mdt decisions were implemented and when decisions changed, it mostly related to patient factors that had not been taken into account prior to the adoption of multi-disciplinary team. analysis of the implementation of team decisions is an informative process in order to monitor the quality of mdt decision-making. purpose: in japan, lateral pelvic node dissection (lpnd) is the standard treatment for locally advanced lower rectal cancer. there are few reports of patients undergoing single-incision plus one port laparoscopic (sils+ ) lpnd even among those undergoing laparoscopic lpnd. the aim of this study is to describe our initial experience and assess the feasibility and safety of sils+ lpnd for patients with advanced lower rectal cancer. methods: a lap protector (lp) was inserted through a . cm transumbilical incision, and an ezaccess was mounted to lp and three -mm ports were placed. a mm port was inserted in right lower quadrant. a single institutional experience of sils+ lplnd for rectal cancer are presented. inclusion criteria was indications for lld were lower rectal cancer with t - , or t - rectal cancer with metastasis of lateral lymph node, as described by the japanese society for cancer of the colon and rectum (jsccr) guidelines for the treatment of colorectal cancer. perioperative outcomes including operative time, operative blood loss, length of stay, postoperative complications, and histopathological data were collected prospectively. introduction: endoscopic stenting with a self-expandable metallic stent (sems) is widely accepted procedure for malignant colorectal obstruction. we assessed the safety and efficacy of insertion of a sems followed by elective surgery as 'bridge to surgery (bts)' in our institute. methods: this study was a retrospective study in our institute. the data was collected from medical charts from january to june . results: a total of consecutive patients underwent radical surgery for colorectal malignancy during this period. in this series, patients ( . %) were diagnosed malignant colorectal obstruction and intended to a bts. the stent was successfully placed in patients and all the patients were planned to undergo radical surgery. the failed patients underwent stoma creation ( patients) and hartmann's procedure. the technical success rate was % and the clinical success rate was %. the median time from sems to surgery was days ( - days) . open and laparoscopic surgery was performed in and patients, respectively, except for one patient refused radical surgery because of a great age. the tumor could be resected in patients (bts patients) with primary anastomosis. however, diverting stoma creation was needed in patients and decompression rectal tube was placed in patient. the entire patient laparoscopically was no conversion to open surgery. there was no anastomotic leakage in bts patients. the median duration of postoperative hospital stay was days ( - days). the overall postoperative complication was % ( / ) including bowel obstruction and anastomotic stricture. the median follow-up period was days. during the follow-up period, patients were relapsed peritoneal dissemination, ovarian metastasis, and liver and pulmonary metastases, respectively. former patients were diagnosed stage iva at the time of primary surgery. one patient died from sudden death. conclusions: our data suggested that routine use of sems insertion was safe and effective procedure for malignant colorectal obstruction as a bts. moreover, laparoscopic procedure was useful procedure in bts patient. the short-and long-term surgical outcomes were also acceptable. introduction: serpin e , also known as plasminogen activator inhibitor- (pai- ) is an inhibitor of urokinase type plasminogen activator (upa) and tissue-type plasminogen activators (tpa ). pai- plays a role in the regulation of angiogenesis, wound healing, and tumor cell invasion; over expression has been noted in breast, esophageal, and colorectal cancer (crc). pai- is also a potent regulator of endothelial cell (ec) proliferation and migration in vitro and of angiogenesis and tumor growth in vivo. the plasminogen/plasmin system plays a key role in cancer progression by mediating extracellular matrix degradation and tumor cell migration. surgery's impact on plasma pai- levels is unknown. this study's purpose was to measure plasma pai- levels before and during the first month after minimally invasive colorectal resection (micr) for crc. objectives: retroflexion in the rectum at the end of a colonoscopy is a requirement for a complete endoscopic evaluation. retroflexion helps to visualize and detect polyps which would be missed otherwise. currently new endoscopes are available which can do retroflexion in the caecum. aim: our study aims to compare the rate of polyp detection rate in cecum and ascending colon with and without retroflexion in cecum. methods: this is a single center, single operator, retrospective study. a total of two hundred patients were involved. a single center irb waiver was obtained. patients were divided into two groups based on the presence/absence of retroflexion in caecum during their colonoscopy. the data was obtained from records. group a (n= ) had colonoscopy without retroflexion in caecum group b (n= ) had colonoscopy with retroflexion in caecum inclusion criteria: patients undergoing screening colonoscopy between the age of and . results: group a: total of patients were screened. a total of polyps were detected in group a. number of cecal polyps were ( . % of total polyp count). number of ascending colon polyp were ( % of total polyp). on analyzing the pathology % of the cecal polyps were tubular adenoma, % hyperplastic polyps % and % lymphoid aggregate. number of ascending colon polyps were , of which % were tubular adenoma, % tubular adenoma and % tubulovillous adenoma group b: total of patients were screened. a total of polyps were detected. number of cecal polyps detected were ( . % of total polyp count). number of ascending of ascending colon polyps were ( %). on analyzing pathology, % cecal polyps were tubular adenoma and % were sessile serrated. out of the ascending colon polyps % were tubular adenoma, % sessile serrated, % tubulovillous and % hyperplastic polyp. side events: two mass lesions were noted in both group a and b. there was incomplete colonoscopy in group a and b. conclusion: this retrospective analysis reveals a small increase in polyp detection in the cecum with retroflexion, especially in detecting sessile polyps which have more malignant potential. however, a large multicenter analysis will be required to validate the above observation. background: while uncommon, rectal prolapse is a disabling condition affecting older females. in a small subset of patients, concomitant organ prolapses with or without incarceration can lead to significant morbidity. as the field of laparoscopy has evolved, minimally invasive surgical options for rectal prolapse have led to improved quality and reduced morbidity for patients suffering this debilitating disease. methods: the - acs-nsqip databases was queried for patients undergoing a traditional or minimally invasive rectopexy based on cpt codes ( , , , and ) . emergent cases and patients with preoperative infections or inflammatory states were excluded. the primary outcome of interest was a -day postoperative composite morbidity score. statistical analysis incorporated multivariate analysis and binomial logistic regression with p. holding significance. results: these inclusion and exclusion criteria identified patients undergoing traditional ( ) and minimally invasive ( ) rectopexy for prolapse between and . patients undergoing traditional rectopexy were older (p. ), had a higher body mass index (p= . ), more comorbid conditions (diabetes, copd, hypertension) and less functional independence (p= . ). patients undergoing a traditional rectopexy had a higher composite morbidity incidence of . % vs. % for minimally invasive rectopexy (p. ). specifically, minimally invasive rectopexy patients had a . % reduction in wound complications (p= . ) and a shorter hospital stay ( . days vs. . days, p . ) compared to a traditional rectopexy. readmission rates were also . % lower in the minimally invasive group (p= . ). after controlling for the differences in the cohorts, a minimally invasive approach was a significant protective factor against the incidence of -day postoperative morbidity (or . , p. ). conclusion: a minimally invasive rectopexy has improved -day postoperative morbidity compared to a traditional rectopexy and should be strongly considered for the treatment of rectal prolapse. objectives: the short-term safety and efficacy of a self-expandable metallic stent (sems) placement followed by elective surgery, "bridge to surgery (bts)", for malignant large-bowel obstruction (mlbo) have been well described. the aim of this study was to investigate the risk factors for postoperative complications and optimal interval between sems placement and surgery in patients with mlbo. methods: retrospective examination of patient records revealed that the bts strategy was attempted in patients with mlbo from january to march in our institution. two of these patients were excluded because they had undergone emergency surgery for sems migration; thus, patients with mlbo who had undergone sems placement followed by elective surgery were included. of these patients, eight had developed postoperative complications (clavien-dindo grading≥ii) (postoperative complication: poc group) whereas patients had no such complications (no poc group). results: univariate analyses showed that the factors of asa score, number of lymph nodes resected, interval between sems and surgery, and preoperative albumin concentration were associated with postoperative complications. multivariate analysis identified only the interval between sems and surgery as an independent risk factor. furthermore, a cut-off value of days for interval between sems and surgery was identified by roc curve analysis. conclusions: an interval of ≥ days from sems placement to surgery is an independent predictive factor for postoperative complications in patients undergoing elective surgery in a bts setting. thus, an interval of over days is recommended for minimizing postoperative complications. haseeb kothar, ronan cahill; mater misericordiae university hospital current clinical advances in operative near-infrared visualisation of cells, tissues and structures are predicated on the use of commercial available near-infrared cameras to excite and visualise emission energy from non-selective, approved compounds (predominantly indocyanine green (icg)). it is expected that new generation compounds wholly selective for specific cellular components are now needed for further advance and a variety of molecular targets have been proposed and are being developed primarily for oncological imaging purposes. recent publications have however suggested icg itself is retained within malignant tissue differently to its uptake and clearance from surrounding non-malignant tissue which is important for two reasons. firstly, it exploits and makes visual the increased vascular permeability and disordered clearance associated with carcinogenesis which is a common endpoint of a variety of mediators including but not limited to vegf. this raises the useful option of targeting downstream effects of cancer compounds on a metabolic basis as opposed to tagging individual cell or antigen components. this means that a single agent could be used to target a variety of cancers rather then needing a specific one for each specific sub-type as well as obviating the issue of cancer cells heterogeneity even in a single cancer deposit. second, it is very likely that some or all of the "localisation" effect of proposed selective compounds may well be due to a similar phenomenum rather then cell-specific binding and may make distinction from other areas of similar metabolic behaviour (ie inflammatory regions) difficult. the crucial step-advance for such agent development so may well relate to timing of compound delivery and "visualisation window" at the region of interest rather then highly selective oncocellular-targeting. to illustrate this in more detail, we have been examining the tissue-specific effects and actions of near-infrared excitation in patients (n= ) with localised malignant colorectal primaries receiving an aliquot of icg before such examination at the time of resection. icg can be selectively apparent in the colorectal primary minutes after its systemic administration likely due to altered vascular dynamics. additional dose-related work has shown that early administration ( - minutes before examination) does not give useful information related to tumour fluorescence. interestingly none of these patients had fluorescence seen within their regional lymphatics but none also had malignant lymph nodes associated with their large primaries on pathological examination. however, this procedure is not usually performed in laparoscopic apr for its technique difficulty, which may lead to increased rates of complications ( fig. ) . here, we compared the feasibility and peri-operative outcomes of the laparoscopic apr with and without pelvic peritoneum closure (ppc) for lower rectal cancer. introduction: there are reports of increased operative duration, blood loss and postoperative morbidity, caused by difficulties in obtaining good visualization and in controlling bleeding when laparoscopic resection is performed in obese patients with colon cancer. purpose: the aim of this study was to investigate the impact of obesity on perioperative outcomes after laparoscopic colorectal resection performed by various operative methods in our department. patients and methods: we conducted a retrospective analysis of patients with colorectal cancer who underwent laparoscopic surgery between january to december . right colectomy was performed in patients, sigmoidectomy in patients, and low anterior resection in patients. the surgical outcomes were compared between non-obese (body mass index [bmi]\ kg/m ) and obese (bmi ? kg/m ) patients. results: right colectomy cases: the amount of blood loss was significantly increased in the obese group compared with the non-obese group, but operation time did not differ significantly between the groups. there were no significant differences between the two groups in the rate of postoperative complications and duration of post-operative hospitalization. sigmoidectomy cases: there were no significant differences between the two groups in operation time and amount of blood loss. even though the preoperative asa score and the rate of postoperative complications were higher in the obese group, the mean postoperative hospital stay did not differ significantly between the two groups. low anterior resection cases: there were no significant differences between the obese group and the non-obese groups in operation time, amount of blood loss, rate of postoperative complications, and duration of post-operative hospitalization. discussion: although there are some reports of increased operative times in obese patients, the operative procedure was not extended in any of the present study patients. the amount of blood loss was significantly increased in the obese group compared with the non-obese group when right colectomy was performed. among the patients undergoing sigmoidectomy, the postoperative rate of complications was higher in the obese group; however, the preoperative asa status was also higher in the obese group than non-obese group, indicating that factors other than obesity may be involved. conclusion: we concluded that laparoscopic colorectal resection appeared to be safe and feasible in both obese patients and non-obese patients. however, bmi may not accurately reflect the amount of visceral fat present. background: for the complete rectal prolapse (basically longer than cm), we thought sling rectopexy was most reasonable to hang up and fix the rectum, which drooped down and prolapsed due to the relaxation of supporting tissue. we considered ripstein method had enough fixed power of rectum to sacrum. however, complications of rectal stenosis, constipation, mesh infection and mesh penetration were reported. therefore, we modified ripstein method to conquer such complications. aim: a prospective study beyond the randomized control trial (rct) between our modified ( introduction: the results of the japan clinical oncology group (jcog) study suggested that total mesorectal excision (tme) and lateral lymph node dissection (llnd) could become the standard treatment for lower rectal carcinoma. however, llnd must also be performed laparoscopically if surgery for lower rectal carcinoma is to be carried out as a completely laparoscopic procedure. transanal tme (tatme) is expected to provide better results than the conventional tme, both oncologically and in terms of pelvic function, and its use has recently been spreading in japan. we started performing laparoscopic tatme+llnd in our department in july and here report the short-term outcomes. subjects and methods: we used laparoscopic tatme+llnd to treat men and women with ct or deeper rectal carcinoma in whom the inferior margin of the tumor was on the anal side of the peritoneal reflection. this was a retrospective study of short-term postoperative outcomes. surgical procedure: laparoscopic surgery was started simultaneously by two teams, one working transabdominally and the other working transanally. the transabdominal team performed the standard proximal llnd and mobilization of the splenic flexure via five ports. they then dissected the bilateral lateral lymph nodes, mainly in the obturator (# ) and internal iliac (# ) groups. during this time, the transanal team performed laparoscopic tatme. finally, both dissection layers were connected and the cancer was excised. results: six patients had clinical stage ii and two had clinical stage iii lower rectal carcinoma. all the patients underwent preoperative chemotherapy with s- +l-ohp. five underwent a sphincterpreserving surgery, and three underwent rectal amputation. the mean operating time was minutes (range, - minutes), and the mean amount of hemorrhage was g ( - g). the mean number of lymph nodes dissected was , and r resection was performed in all the cases. the mean length of hospital stay was days, and a postoperative complication of clavien-dindo grade iii or higher occurred in one patient (anastomotic failure). conclusions: laparoscopic tatme+llnd performed by two teams simultaneously is an extremely useful procedure that not only reduces operating time, but also is less invasive than laparoscopic surgery. it may also be effective for improving curative nature, nerve preservation, and anal function. objective: in laparoscopic appendectomy, the base of the appendix is usually secured by applying a roeders knot. the aim of this study was to compare the advantages of using staplers and hem-olocks for securing the base of the appendix. method: the study included patients between age of to years with acute appendicitis randomly divided into two groups. in the first group, the base of the appendix was secured using roeders knot. in the second group, mesoappendix was not dissected and was included in the endostapler jaws. the primary outcome was overall morbidity. secondary outcomes were total duration of surgery, total length of stay and ease in difficult cases. result: no morbidity was recorded in any group. the time of the operative procedure was significantly longer in the cases with roeders knot than in the stapler group (p. ) as mesoappendix was not dissected in the later. cases with unhealthy base were progressed to laparoscopic quadricolectomy. apart from the ease of applying a stapler, cases of second group with gangrenous base were easily tackled using endostapler, avoiding the need of a hemicolectomy. conclusion: all forms of closure of the appendix base are acceptable, but endostapler technique apart from providing a secure base, reduces operative time and is an essential tool in cases of gangrenous base. introduction: accurate staging is essential to estimate the prognosis of patients with colorectal cancer (crc) and lymph node evaluation is key to determine it. in non-metastatic crc, the number of harvested lymph nodes is the strongest prognostic factor for outcome and survival. additionally, it is thought that a higher lymph node yield may be representative of a higher quality of surgical care. due to the importance of the association between lymph node evaluation and outcome in crc, it is necessary to evaluate factors which may affect lymph node harvest. introduction: hatmann's procedure is commonly done in treating complicated diverticulitis, negleccted rectal trauma with sepsis and sometimes malignancy. the traditional techniques to restore the intestinal continuity after hartmann's procedure were for many years the standard of care in these operations, but in fact they carry many morbidity and even mortality and failure. laparoscopic techniques is not only carry the advantage of minimal invasive surgery, but also of better visualizationn and magnification. the aim is evaluating the outcome of using the laparoscope in reversal of hartmann's procedure as regard feasibility and safety. patients and method: forty patients were subjected to laparoscopic reversal of hatmann's procedure in tanta university hospital, there ages ranged between to years, the time elapsed after the original operation ranged from months to years, excluding advanced malignany. conversin occurred in cases due to extensive adhesions and bleeding. results: no mortality, or major morbidity in our study and only single leak treated by covering ilestomy. conclusion; laparoscopic hartmann's procedure is feasible, promising tehnique with minimal morbidity. background: minimal invasive surgery has been well established in the elective colorectal surgery and it has been proven better clinical outcome compared with open surgery. in the emergent setting, laparoscope is used mostly in the colecystectomy, appendectomy but laparoscopic emergent colorectal surgery is limited for it's complexity and difficulity. the aim of this study was to envaluate the feasibility of laparoscopic emergent colorectal surgery. methods: this study is prospective collected, observational single center study of patients undergoing laparoscopic emergent colorectal surgery from to . the patient demographics, surgery indication and detail, complication, clinical outcome and hospital stay were collected and analyzed. results: there are total emergent colorectal operations and patients were managed with minimal invasive method. among these laparoscopic emergent surgery, there are male patients and female patients. mean age of the patients was . years (range - years). the main indication for operation: perforation . % ( / ), leakage after elective colorectal surgery . % ( / ), obstruction . % ( / ), ischemia colitis . % ( / ,), bleeding . % ( / ). there are cases in asa , cases in asa , cases in asa . the qsofa score for sepsis: cases was , cases was , cases was , case was . there are cases undergoing laparoscopic lavage with diverting stomy, cases were hartmann procedure, cases were anterior resection, cases were right hemicolectomy, cases were perforation repair, cases were redo anastomosis. there are cases coversion to open method including cases were due to bowel adhesion, cases were due to bowel distension, case was due to severe shock status. mean operative time is . minutes. the overall mortality rate was . % and major complication rate (clavien-dindo grade above ) was . %. re-operation rate was . %. the mean hospital stay was . days. conclusions: this study presents evidence of an initially clinical outcome in emergent laparoscopic colorectal suregry. in the absence of large case series, the benefits of a laparoscopic approach should befall to at least a minority of these patients. confocal laser endomicroscopy (cle) can provide real-time observation of the cell structure and tissue morphology. in our study, we aim to assess the situation of anastomotic perfusion using cle. method: the experimental rabbits were separated into two groups: group a (good anastomotic perfusion, n= ), group b (poor anastomotic perfusion, n= ). the partial colectomy and anastomosis was performed for group a and b. then detection for anastomotic perfusion using cle was carried out after the surgery. during the continuous scanning, we counted the number of blood cells that cross over the certain point of anastomotic stoma in the same period. results: assistant with fluorescein sodium, the blood vessels are highlighted. we can see significant difference of imaging effect between group a and group b. the average number of blood cells are . /min of group a and . /min of group b (p. ), which has significant difference. conclusion: cle can allow real-time observation of the blood flow of anastomotic stoma in vivo. therefore, it is feasible to assess the anastomotic perfusion using cle in colorectal surgery. cigdem benlice, ahmet rencuzogullari, james church, gokhan ozuner, david liska, scott steele, emre gorgun; cleveland clinic background: intraoperative colonoscopy (ioc) is an adjunct in colorectal surgery (crs) especially in patients with malignancies in order to detect location of the primary or synchronous lesions as well as assessing anastomotic integrity. however, effects of intraoperative colonoscopy on short term outcomes during crs is a concern. this study aims to evaluate safety and feasibility and post-operative outcomes of intraoperative colonoscopy in left-sided colectomy patients for colorectal cancer patients by using the nationwide database. patients and methods: patients undergoing elective left-sided colectomy with low pelvic anastomosis without any proximal diversion for colorectal cancer were reviewed from the american college of surgeons national surgical quality improvement program (acs-nsqip) proceduretargeted database ( ) ( ) ( ) according to their primary procedure current procedural terminology (cpt) code. subsequently, patients who underwent intraoperative colonoscopy were identified from concurrent cpt codes and divided into two groups based on the simultaneous intraoperative colonoscopy. demographics, comorbidities, -day postoperative complications were evaluated and compared between the groups. multivariate logistic regression was conducted adjusting for significant factors between the groups. results: a total of patients were identified and ioc was performed for ( . %) patients. objective: laparoscopic ileostomy commonly performed for the patients with colorectal obstruction due to cancer, peritonitis with perforation of colon or the other reason. reduced port surgery is a novel technique that may be performed when considering minimally invasive surgery and desiring a cosmetic benefit. the aim of this study was to evaluate safety and feasibility of reduced port laparoscopic ileostomy for the patients with advanced colorectal cancer before chemotherapy. methods: between july and august , patients who underwent reduced port laparoscopic ileostomy were included ( male and female, age: years old. the outcomes were evaluated in terms of operation time, intraoperative blood loss and perioperative complications. sugical procedures: the patients were placed in the supine position and the operator stood left side. an access device with the wound-protector (ez access, hakko, nagono, japan) was inserted on the future ileostomy site in the right lower abdomen, inserting two of -mm trocars, maintaining pneumoperitoneum at mmhg with carbon dioxide. a -mm trocar was inserted in the left lower abdomen. a -mm flexible laparoscope was inserted from access device port. after exploring abdominal cavity, ileum end was identified. then the marking using dye was put on the ileum of cm proximal from the ileum end. the ileum marked by dye was grasped, and extracted through the access devise. then a blooke ileostomy was created. results: reduced port laparoscopic ileostomy was performed for patients with colorectal obstruction due to cancer before chemotherapy. the mean operative time was minutes, the mean blood loss was . ml. three patient received one additional port. there were no intraoperative complications. five patients ( . %) experienced postoperative complications (two of deep surgical site infection, one of pneumonia, one of outlet obstruction and one of renal dysfunction). there were no other intraoperative or postoperative complications. conclusion: reduced port laparoscopic ileostomy is a safe and feasible procedure for the patients with advanced colorectal cancer before chemotherapy. methods: we performed elective lcr on patients for primary colorectal cancers between june and june . seventy-two patients were excluded in this study following reasons: patients underwent multiple organ resection, and colorectal cancer was diagnosed with stage iv in patients. accordingly, patients were eligible for comparative analysis, with in group po (post operation) and in group c (control). in group po, past operative procedures were as follows: appendectomy ( %), digestive tract ( %), hepato-billiary-pancreatic ( %), gynecologic ( %), urologic surgery ( %), and others ( %). results: there were no significant differences between two groups in asa (grade≤ : vs. %, p= . ), bmi ( introduction: the treatment of rectal cancer requires highly skilled practice by the entire multidisciplinary team. important aims of treatment are: to reduce the risk of residual disease in the pelvis, with lower morbidity and to preserve good sphincter function. the tata procedure is transanal transabdominal radical proctosigmoidectomy with coloanal anastomosis. this technique was first developed in by dr. gerald marks to avoid a permanent colostomy for low-lying rectal cancer. this study reports the long-term results of tata procedure for low rectal cancer. methods and procedures: a prospective study was on patients with low rectal cancer between april and july in a tertiary referral university-affiliated center specializing in laparoscopic surgery. all resections were carried out by a team of dedicated colorectal surgery and standard protocol was used for all pre-and-post-operative care. all the patients underwent total mesorectal excision. results: consecutive patients ( male, female, mean age ) underwent tata procedure, of them ( , %) after neoadjuvant radiochemotherapy. the mean operation time was min (range - ) and the mean estimated blood loss was ml (range - ). the overall incidence of morbidity was , % ( / ) and the mean hospital stay was , days. the mean follow-up period was , (range, - ) months with a recurrence rate of , % ( / ), overall estimated -year survival , % and the disease-free survival rate , %. conclusion: laparoscopic total mesorectal excision with tata procedure is safe with excellent local recurrence and disease-free survival rate. jacek piatkowski, md, phd, marek jackowski, prof; clinic of general, gastroenterological and oncological surgery introduction: more than years ago, laparoscopic technique was considered to be a fully accepted surgical method for treatment of rectal cancer. the following years are a further search for a new surgical method that reduces invasiveness and improves treatment outcomes. it seems that such a method is transanal total mesorectal excision. the aim of this study was to evaluate the new method of rectal cancer surgery (tatme) after years of its use. methods: radicality of treatment (r resection, local recurrence), outcome of surgical treatment and quality of life of patients after surgery were evaluated. results: in the period from . . . - . . . patients ( men, women) were operated in the clinic. in cases the indication for surgery was lower and middle rectal cancer and in cases high grade dysplasia. all patients underwent laparoscopic rectal proctectomy with transanal access (tatme). in all cases, complete oncological radicalization (resection r ) was obtained. the average operation time was minutes. we had used two teams approach (cecil approach) with laparoscopic sets -abdominal and perineal starting at the same time. in the postoperative course, patients had signs of anastomosis leak ( of them required reoperation). the follow-up period is - months. none of the patients had any recurrence of cancer. conclusions: . transanal tme for rectal cancer surgery is an alternative method to conventional laparoscopic surgery. . in a large proportion of patients with lower and middle tumors, the rectum can avoid abdomino-perineal resection with permanent colostomy. background: the double stapling technique (dst) has widely spread colorectal anastomosis especially for anastomosis after low anterior resection. as for the colorectal cancer treatment, heald reported total mesorectal excision (tme) in , and has been accepted as the standard technique for rectal resection due to the decreased local recurrence rate and improved functional results. with advent of dst, there is a background that it has become possible to preserve anus, even in the case with the lesion at lower rectum. laparoscopic surgery for colon cancer was introduced in the s, and has had promising results including long-term outcomes. according to the spread of laparoscopic surgery, laparoscopic surgery had been applied to the rectal resection, with technical difficulty. one of the reasons for the difficulty is that the high rate of anastomotic leakage, a critical adverse effect of low anterior resection (lar). thus, risk factors for anastomotic leakage were widely discussed, including technical factors such as pre-compression and number or firing. the decisive difference in conventional lar and laparoscopic lar in dst, is the stapler used for transection of the rectum. the laparoscopic staplers which are currently available are thought to be not ideal, and there is little evidence of specific specifications of stapler for laparoscopic surgery. materials and methods: all method described in this study was approved by the institutional ethical review committee. we reviewed the colon and rectal wall thickness according to histological examination using h&e staining of distal margin of resected specimen of the patients who conclusions: rstc for severe acute uc is at least as safe as the laparoscopic approach. although the robotic cohort had more comorbidities, major postoperative complications, readmissions, and reoperation rates were less when compared to lstc. rstc was also associated with an earlier return of bowel function and shorter length of stay. a prospective study with larger numbers is needed to see if the superiority of robotic versus laparoscopic approaches is reproducible. s surg endosc ( ) introduction: complete mesocolic excision (cme) has been advocated based on oncologic superiority, but is not commonly performed in north america. furthermore, many data are limited to case series with few comparative studies. therefore the objective was to systematically review studies comparing the short-and long-term outcomes between cme and non-cme colectomy for colon cancer. methods: a systematic review was performed according to prisma guidelines of medline, embase, healthstar, web of science, and cochrane library. studies were only included if they compared conventional resection (non-cme) to cme for colon cancer. quality was assessed using the methodological index for non-randomized studies (minors). the main outcome measures were short-term morbidity and oncologic outcomes. study eligibility, data extraction and quality assessment was performed by two independent reviewers, and disagreements resolved by consensus. weighted pooled means and proportions with %ci were calculated using a randomeffects model when appropriate. results: out of citations, studies underwent full-text review and met the inclusion criteria, of which were unique series. mean minors score was . (range - ). the mean sample size in the cme group was (range - ) and (range - ) in the non-cme group. in the unique studies, included only right-sided resection, and . % ( % ci . - . ) of the remaining were right-sided colectomies. of the studies that reported surgical approach, . % ( %ci . - . ) of cme were performed laparoscopically. there were papers reporting plane of dissection, with cme plane achieved in . % ( . - . ). mean or time in cme group was minutes (range - ) and in non-cme group minutes (range - ). perioperative morbidity was reported in studies, with pooled overall complications of . % ( %ci . - . ) for cme and . ( %ci . - . ) for non-cme resections. anastomotic leak occurred in . % ( %ci . - . ) of cme versus . % ( %ci . - . ) in non-cme colectomies. cme surgery consistently resulted in more lymph nodes retrieved, longer distance to high tie, and specimen length. there were studies that compared -or -year overall or disease-free survival, or local recurrence. only studies reported statistically significant higher disease-free or overall survival in favour of cme. local recurrence was lower after cme in of reported studies. conclusions: the quality of the current evidence is limited and does not consistently support the superiority of cme. more rigorous data are needed before cme can be recommended as the standard of care for colon cancer resections. gilberto lozano dubernard, md, facs, ramon gil-ortiz, md, gustavo cruz-santiago, md, bernardo rueda-torres, md, javier lopez-gutierrez, md, facs; hospital angeles del pedregal introduction: to assess the feasibility of a single-stage colorectal laparoscopic re intervention without ostomy. colonic laparoscopic interventions on patients that previously underwent a minimally invasive procedure, constitutes the current boundary in the management of the acute colorectal pathology. that includes, patients with fecal peritonitis due to diverting procedures already treated surgically. the outcome of our patients could significantly improve if the surgical procedure is performed in one time, with no stoma. method and procedures: from september to june , one hundred thirty-two patients underwent colorectal laparoscopic surgery. five of these patients developed complications: three perforations due to colonoscopy and two due to dehiscence of the anastomosis. these five patients underwent a second laparoscopic procedure that included resection and anastomosis. no stoma required. results: all five patients underwent a second laparoscopic procedure due to an anastomosis leak. no stoma was required. the procedure consisted on resection of the previous anastomosis, re anastomosis, abdominal lavage, aspiration and drains placement. all of them supported with parenteral nutrition. there were no surgical complications. only one patient developed pneumonic symptoms that were solved. conclusion: the reported results, regarding no conversion rate, nor mortality, on our series of patients, suggest that single stage laparoscopic re intervention is feasible, despite fecal peritonitis. introduction: total mesorectal excision is known to be a gold standard surgical procedure for the rectal cancer. subsequently complete mesocolic excision (cme) is recognized as an essential surgical procedure for the colon cancer. the transverse colon is relatively minor location for colon cancer. variety of vessels and mobilization of splenic flexure and dissection close to pancreas make operations for the transverse colon cancer complicated. laparoscopic transverse mesocolic excision in our hospital is presented. method: laparoscopic surgery is conducted with five trocars under the lithotomy position. inferior mesenteric vein is cut after dissection of the descending colon with medial approach. the lower edge of pancreas is exposed near the inferior mesenteric vein and is dissected along toward the tail of pancreas. the splenic flexure is mobilized with lateral approach and the dissection between transverse mesocolon and the lower edge of pancreas is continued in the direction to the pancreas head. coming to the exposure of superior mesenteric artery and vein, the origin of middle colic artery and vein are cut. the transverse mesocolon is separated from the pancreas head and the duodenum with preserving the gastrocolic trunk of henle and the right gastroepiploic vein. the hepatic flexure is mobilized and cme for the transverse colon is finished. this method, the 'tail to head of pancreas' approach, we called, was performed from september . this method is well performed with one series of surgical view, and seems to be a simple procedure as cme with central vascular ligation for the transverse colonic cancer. there were no intraoperative complications, and one postoperative pancreatitis with grade ? of clavien-dindo classification of surgical complications. conclusion: our method, the 'tail to head of pancreas' approach, with transverse mesocoloc excision is simple, safe and feasible. the introduction: anastomotic complication after stapled anastomosis in colorectal cancer surgery is a considerable problem. there are various types of anastomotic complication and they have different severity. this study was aimed to evaluate the impact of intraoperative colonoscopy on detection of anastomotic complication, and its effectiveness in treatment of anastomotic complications after anterior resection (ar) and low anterior resection (lar) for colorectal cancer intraoperatively. methods: from dec. to jul. , a total of patients who underwent anastomosis between sigmoid colon and rectum after colorectal resection were reviewed retrospectively. intraoperative colonoscopy was performed routinely since december in our hospital after anterior resection and low anterior resection. to identify effectiveness of intraoperative colonoscopy, we compared postoperative complications with non-intraoperative colonoscopy group during previous months. intraoperative colonoscopy was performed after anastomosis to visualize the anastomosis line and to perform an air leakage test. if anastomotic defect and moderate bleeding were found in intraoperative colonoscopy, it was managed by means of reinforcement suture or transanal suture repair. we used logistic regression to analyze anastomotic complication between two groups with or without intraoperative colonoscopy. results: of the patients who were performed intraoperative colonoscopy after ar (n= ) and lar (n= ), abnormal findings including bleeding and air leak were found in patients ( . %). among those, cases were observed without any procedure, additional procedures were performed in patients ( . %, transanal suture ( ), lembert suture ( )). postoperative complication was developed in patients; patients had anastomosis bleeding ( . %), patients had ileus ( . %), patient had pneumonia ( . %), patients had minor complication ( . %, acute urinary retention, chylous drainage, laparoscopic port site bleeding). among patients who had anastomosis bleeding, patients were treated by endoscopic clipping, patients were cured by conservative treatment. there was no postoperative anastomotic leakage. the cases of ar and lar were and in non-intraoperative colonoscopy group, there was no significant difference between two group (p= . ). the proportion of laparoscopic surgery was . % and . % on intraoperative colonoscopy and non-intraoperative colonoscopy group, respectively, there was significant difference statistically (p= . ). however, there was no significant difference in anastomotic complication rate between two groups. (rr= . , % ci, . - . ). conclusions: although there was no significant difference in postoperative anastomotic complication rate between two groups, intraoperative colonoscopy may be valuable method for decreasing postoperative complication by visualizing anastomosis line and performing additional procedure. conclusion: it was suggested that lymph node dissection of both middle and left colic regions is necessary for splenic flexure colon cancer, because lymph node metastasis was recognized in both region. surg endosc ( ) :s -s the aims: laparoscopic right hemicolectomy became the standard of care for treating cecum, ascending and proximal transverse colon cancer in many centers. most centers use laparoscopic colectomy with extracorporeal resection and anastomosis (lc). single-incision laparoscopic colectomy with intracorporeal resection and extracorporeal (sc) remains controversial. the aim of the present study is to compare these two techniques using propensity score matching analysis. methods: we analysed the data of patients who underwent laparoscopic right hemicolectomy with lc or sc between december and december . the propensity score was calculated from age, gender, body mass index, the american society of anesthesiologists score, previous abdominal surgery and d lymphnode dissection. short-term outcomes were recorded. postoperative pain was evaluated using a visual analogue scale (vas) and postoperative analgesic use as outcome measure. results: the length of skin incision in the sc group was significantly shorter than in the lc group: median (range) ( . - ) cm verses ( - ) cm (p= . ). the vas score on day and day after surgery was significantly less in the sc group than in the lc group: median (range) ( - ) verses ( - ) on day (p= . ) and median (range) ( - ) verses ( - ) on day (p= . ). significantly fewer the number of requiring analgesia in the sc group on day and day after surgery: median (range) ( - ) times verses ( - ) times on day (p= . ) and ( - ) times verses ( - ) times on day (p= . ). there were no significant differences in operative time, intraoperative blood loss, the number of lymph nodes removed and postoperative courses between the groups. conclusions: sc for right colon cancer is safe and technically feasible. sc reduces the length of skin incision and postoperative pain compared with conventional lc. patients were divided into the following groups: cephalo-medial-to-lateral approach group (cml group, n= ) and medial-to-lateral approach group (ml group, n= introduction: laparoscopic technique has been widely used in the treatment of colorectal cancer, while playing its minimally invasive advantages, but also achieved a good effect of radical oncology. however, t colorectal cancer is not recommended laparoscopic surgery. methods: retrospectively collected pt colorectal cancer data from to in guangdong general hospital, all cases were undergoing radical surgery. results: a total of cases were enrolled in the pt group, including cases of laparoscopic group, cases of open group, conversion rate was . %. there was no difference in baseline data (age, sex, bmi, asa, etc.)(p. ). there was a significant difference between the two groups (p. ) in blood loss, postoperative complications and postoperative recovery index. in the pathologic t a/b, combined-organ resection, postoperative recurrence, the laparotomy group had more cases, and there was a statistically significant difference between the two groups (p\ . ). the -and -year overall survival rates were . % and . % for the lap group and . % and . % for the open group (p= . ). meanwhile, the -and -years disease-(p= . ). iiic stage, lymph node status, ca - and adjuvant chemotherapy were independent prognostic factors affecting overall survival. the age, pt a/b, iiic stage, ca - and adjuvant chemotherapy were independent influencing factors of disease-free survival. conclusions: laparoscopic surgery for pt colorectal cancer surgery, it is not only in the play of its minimally invasive but also obtained with the similar long-term effect. but we need more multicenter, prospective, and large sample clinical studies to validate our findings. introduction: lymph node (ln) retrieval after surgery is important. in the present study we evaluated the efficacy of the fat dissolution technique using fluid containing collagenase and lipase to avoid staging migration after laparoscopic colorectal surgery. methods: seventeen patients who underwent laparoscopic ln dissection for colorectal cancer were evaluated. first, unfixed lns within the resected mesentery were explored by visual inspection and palpation immediately after the operation by the surgeon, which is the most common practice in japan. subsequently, the fat dissolution technique was used on remnant fat tissue, and the lns were evaluated again. the primary endpoint was whether the second assessment increased the number of lns evaluated. results: the median number of lns identified at the first and second assessments was and , respectively, resulting in a significant increase in the total number of lns evaluated ( vs. , p\ . , paired t-test). one positive node was identified among all the additional lns identified ( . %; / ). although staging was not altered in any patient, the second assessment resulted in an increase in the originally insufficient number of lns evaluated (\ for stage ii) in three patients, whose treatment may be altered. tumor cells detected after the fat dissolution technique were stained with carcinoembryonic antigen and cytokeratin- . conclusion: using the fat dissolution liquid on remnant fat tissue of the mesentery of the colon and rectum enabled identification of additional lns. this method should be considered when the number of lns identified is not sufficient after conventional ln retrieval, and may avoid stage migration. aim: the aim of this study is to evaluate the pathological resection margin after laparoscopic intersphincteric resection for low rectal cancer. method: from to , there were eight laparoscopic intersphincteric resection cases for low rectal cancer. we evaluated the clinicopathological findings and the positivity of pathological resection margin. results: the median distance from the anal verge to the tumor was mm (range, - ), and the median diameter of the tumor was mm (range, - ). there was no case with neoadjuvant therapy. the estimated tumor depth were ct in cases ( . %) and ct in cases ( . %), and the actual tumor depth were ptis in cases ( . %) and pt in cases ( . %) and pt in cases ( . %). the median distal resection margin was mm (range, - ). pathological resection margin, such as the proximal, distal and circumferential margin was negative in all cases ( %). there was no mortality, but morbidity occurred in two cases (one case of anastomotic leakage and one case of small bowel obstruction). no recurrence nor distant metastasis was observed in the follow up period. conclusion: there was no positive resection margin case in the series. our patient selection, indication and the technique were considered to be precise and appropriate. introduction: the fistulas of the intestine to the vagina or the bladder include a highly morbid entity, with several functional limitation and loss of the quality of life, its diagnosis is complex and more than its treatment, which include a wide range of possibilities that go from the simple derivative colostomy in search of the spontaneous closure of the fistula, under the complete correction of the pathology with resections, anastomosis and mini-vasive reconstructions. give to know our experience in the minimally invasive treatment of whole vaginal and whole vesicial fistules by laparoscopic via, for the last years. results: a total of patients were operated in this period, women and men, all those by laparoscopic via, with intestinal resection, in thick intestine cases, in one small intestine and in another case with the commitment of the two, everyone restriction and intestinal anastomosis and in no matter were colostomy, primary closures of the fistula in patients were required, conversion to open surgery in a case and there was no recurrence, patients had prolonged hospitalization for localized infections, a requirement reintervencion for revision. a patient suffried a umbilical eventration for the extraction site, which was corrected one year after laparoscopy. conclusion: minimally invasive surgery in patients with this type of pathology becomes an excellent strategy for the integral management of these patients. group work guarantees good results. robbie sparks, dr, ronan cahill; mater misericordiae university hospital background: precise preoperative localisation of colonic cancer is a prerequisite for correct oncological resection. effective endoscopic lesional tattoo is vital for small, radiologically unseen tumors planned for laparoscopic resection but its practice may be imperfect. methods: retrospective review of consecutive patients with preoperative endoscopic lesional tattoo who underwent laparoscopic colonic resection identified from our prospectively-maintained cancer database with supplementary clinical chart and radiological, histological, endoscopic and theatre database/logbook interrogation. results: patients ( males, mean age years, median bmi . kg/m , left sided lesions, screen detected, benign polyps, % conversion rate). in operations ( %) tattoo visibility was documented with tattoo absence noted in ( . %) although tattoo was identifiable in the pathological specimen in four. in those with "missing tattoos", six of the lesions were radiologically occult and in three the tumor was found in a different colonic segment then had been judged at colonoscopy. four patients had on-table colonoscopy and five were converted to laparotomy ( % conversion rate, p. ). mean postoperative length of stay was . (range - ) days. one patient's segmental resection contained only benign pathology requiring a second operation to remove the cancer. on univariate analysis, time between endoscopy and surgery (but not patient age, gender, bmi, endoscopist or surgeon seniority, tumor size or location) was significantly associated with absence of tattoo intraoperatively (p= . ). conclusion: recording related to tattoo is variable but definite lack of gross tattoo visualisation significantly impacts the procedure. the mechanism of tattoo absence is multifactorial needing careful consideration but solvable. the aim of the present study was to perform a systematic review of the literature to determine the role of antibiotics in the management of acute uncomplicated diverticulitis (aud). diverticular disease is the most common disease of the large bowel and poses a significant burden on healthcare resources. in the united states alone, the cost of diverticular disease has been estimated to be over $ billion making it the fifth most important gastrointestinal disease economically. the use of antibiotics in the management of aud, however, is primarily based on expert opinion as current high-quality evidence is lacking. recent studies have not only questioned the optimal type and duration of antibiotic regimens, but whether antibiotics provide any benefit in the treatment of aud. conclusions: antibiotic use in patients with acute uncomplicated diverticulitis is not associated with a reduction in major complications, readmissions, treatment failure, progression to complicated diverticulitis, or need for elective and emergent surgery. however, it increases the length of hospital stay. given the risk of selection bias in included studies, further randomized trials are needed to clarify the need for antibiotics in uncomplicated diverticulitis. laparoscopic para-aortic lymph node resection for colorectal cancer aim: we want to highlight the feasibility of a sigmoidectomy using total laparoscopic with a transanal extraction of the specimen. methods: it is a -year-old female patient, obese (bmi= kg/m ) to the antecedents of laparoscopic cholecystectomy and chronic constipation. she was treated three months ago for a sigmoidal diverticulitis complicated with a pelvic abscess. the evolution has been favorable under antibiotic therapy and percutaneous drainage of the abscess. the colonoscopy showed a multiple diverticula located between and cm from the anal verge. prophylactic sigmoidectomy was performed laparoscopically using trocars ( mm supra ombilical, mm fid and mm right flank). the specimen was extracted transanally, thus avoiding a pubic incision. the steps of the intervention were: -mobilisation of left colon -closing of distal left colon stump -rectal stump lavage -opening on the rectum -transanal introduction of the anvil -specimen transanal extraction -closing og rectal stump -colonic positioning of the anvil -coloractal anastomosis. results: the intervention was minutes. no perioperative incidents. the liquid regime was authorized on the night of the intervention. the operating procedures were favorable with an exit to j post operative. the anapath examination of the surgical specimen confirmed the presence of sigmoidal diverticula. conclusion: laparoscopic sigmoidectomy with transanal extraction of the specimen for benign desease is a seductive technique with satisfactory results. it avoids a pubic incision with its parietal and aesthetic complications. chengzhi huang; guangdong general hospital (guangdong academy of medical science) background: colorectal cancer (crc) is one of the most common malignant diseases over the world. of the causes of the death of crc, metastasis to liver or lung are the major factors. however, there is still lack of precise tumor biomarker that precisely predict the clinical outcome of crc. the salt-inducible kinase (sik ) encodes a serine kinase of amp-activated protein kinase (ampk) family, which may play critical roles in tumorigenesis and tumor progression. this study aimed the study the expression and clinical significance of sik and crc patients. methods: the expression of sik protein was measured by western-blot and analysis of immunohistochemistry. sik mrna expression in cancerous tissue was measured by rt-pcr. results: the expression level of sik was correlated with the following factors: tumor invasion (t stages), lymph node metastasis, clinical stages (tnm) and tumor location. the down-regulated sik implies poor clinical outcome measured by kaplan-meier analysis (p-value. ), and may act as an independent risk factor of crc patients. background: surgical specimens for resected colon cancer vary in quality and there remains no universally accepted technique to guide resection margins. a minimum of lymph nodes provides some quality assurance, however this remains a crude marker of optimal oncological surgery. a tool to precisely identify lymphatic drainage within the mesentery could improve the oncologic quality of resection and better guide adjuvant treatment through more optimal mesenteric lymphadenectomy. while fluorescence imaging (fi) has been described to identify nodal disease in several other cancers, feasibility and best practices have not been established in colon cancer. we describe a novel technique of fi using indocyanine green (icg) to identify lymphatic spread and potentially guide optimal mesenteric lymphadenectomy in colon cancer. methods: three consecutive patients with colon cancer undergoing a laparoscopic resection had peritumoral subserosal injection of icg for fi after extracorporealization of the mobilized specimen. three concentrations of icg were injected − mg/ ml, mg/ ml, and mg/ ml. a total of ml was given for each patient. using a modified laparoscopic camera, the icg was excited by light in the near-infrared (nir) spectrum, for real-time visualization of the lymphatic drainage. the main outcome measure was identification of lymphatic drainage. results: three patients with right-sided primary colon cancer were evaluated. all three patients had successful identification of the lymphatic drainage pattern along the mesentery. the most successful protocol was ml (concentration mg/ ml) subserosal injection at points within close proximity ( cm) of the tumor with a -gauge needle, then waiting minutes for complete mapping. no intraoperative or injection-related adverse effects occurred with -day follow-up. the median lymph node yield was . all specimens had tumor-free margins. conclusion: from this small series, fluorescence imaging with icg is a potentially safe and feasible technique for identifying mesocolic lymphatic drainage patterns. this proof of concept and protocol will lead to future studies to examine the utility of fluoresence imaging to guide more precise surgery in colon cancer. introduction: anastomotic leakage in colon/rectal surgery is a dangerous event with an occurance rate ranging from to %. the associated mortality rate is between - %. the white-light intraoperative subjective surgical assessment (the most frequently used approach) underestimates the actual anastomotic leakage rate. intraoperative tissue perfusion assessment by indocyanine green (icg)-enhanced fluorescence has been reported in multiple clinical scenarios in laparoscopic/ robotic surgery, as well as for for bowel perfusion assessment. this technology can detect microvascular impairment, potentially preventing anastomotic leakage. we reviewed the literature and present our data to evaluate the feasibility and usefulness of icg-enhanced ?uorescence in the intraoperative assessment of vascular peri-anastomotic tissue perfusion in colorectal surgery. methods and procedures: a pubmed literature narrative review has been performed. moreover, out of a total of robotic colorectal cases, we retrospectively analyzed icg-enhanced fluorescence robotic colorectal resections ( left colectomies- rectal resections- right- transverse- pancolectomy). results: after icg-technology use, the biggest (n[ ) case-series showed a rate of . - % of cases in which they changed the level of resection based on icg. icg technology may variably reduce the anastomotic leak rate from to %. however, the threshold values to define the actual sub-optimal perfusion are still under investigation. in our experience, out of icg cases performed: the conversion, intraoperative complication, dye allergic reactionand mortality rates were all %. post-op surgical complications: case of leak ( , %) and sbo for incarcerated hernia ( . %). in cases, with normal white-light assessment, the level of the anastomosis was changed after icg showed ischemic tissues. despite the application of icg, anastomotic leak has been registered. conclusions: icg-enhanced ?uorescence may intraoperatively change the white-light assessed resection/anastomotic level, potentially decreasing the anastomotic leakage rate. our data shows that this technology is safe, feasibile and may prevent anastomotic leakage. however, the decision making is still too subjective and not data driven. at this stage icg, beside being a promising technique, doesn't have high level of evidence (most of the reports are retrospective). some randomized prospective trials with an adequate statistical power are needed. a precise injection dose and timing standardization is required. the main challange is to develop a method to objectively obtain a real-time intensity assessement. this may provide objective metric tresholds for an intraoperative evidence/data-based surgical decision making. introduction: according to the world health organization, colorectal cancer is the rd most commonly diagnosed cancer in the world. one of the main risk factors for the development of colorectal cancer is obesity. obesity is seen to increase the risk of colorectal cancer by % in women per kg/m and % in men per kg/m . bariatric surgery is one of the treatments that is considered to achieve and sustain a significant amount of intentional weight loss in patients. considering that fact that bariatric surgery decreases obesity, this intentional weight loss would seem to provide a favorable outcome in terms of diagnosis and prognosis of colorectal cancer. a systemic review of the literature was conducted via pubmed to identify relevant studies from january through may . the main outcome for this study is to assess whether patients who underwent bariatric surgery (restrictive and malabsorptive procedures) had an increased or decreased risk of colorectal cancer. all studies included in this meta-analysis are retrospective cohort studies. results were expressed as standard difference in means with standard error. statistical analysis was done using fixed-effects meta-analysis to compare the mean value of the two groups between bariatric surgery and non-surgery in patients with colorectal cancer. (comprehensive meta-analysis version . . software; biostat inc., englewood, nj). results: four out of studies were quantitatively assessed and included for meta-analysis. among the four studies, , underwent bariatric surgery and , did not undergo bariatric surgery. there is a significant decrease ( . ± . ; p= . ) in the risk in patients developing colorectal cancer in patients who underwent bariatric surgery compared to those who didn't get surgery. conclusion: bariatric surgery patients appear to have a decreased risk of colorectal cancer compared to patients who did not have bariatric surgery. guh jung seo, hyung-suk cho; department of colorectal surgery, dae han surgical clinic, gwangju, south korea introduction: the incidence of rectal carcinoid tumors is increasing due to the widespread use of screening colonoscopy. endoscopic mucosal resection (emr) is a useful method for small rectal carcinoid tumors (≤ mm) because of its simplicity, quick procedure and low complication rates. we aimed to describe our experience and evaluate the outcomes of emr for rectal carcinoid tumors. the patients enrolled in this study were patients with small rectal carcinoid tumors who underwent emr using a submucosal injection technique of epinephrinesaline mixture between august and october . all medical records, including characteristics of the patients and tumors, complications, were retrospectively reviewed. results: the patients were men and women, with a mean age of . years (range, - years). en block resection was performed by emr in all cases. the endoscopic mean size of tumors was . mm (range, - mm). the pathologically measured mean size of the resected specimens was . mm (range, - mm). the mean size of resected carcinoid tumors was . mm (range, . - mm). the tumor shape was submucosal tumor in and polyp in . histological examination revealed that cases had resection margin positive of tumor and case had undetermined resection margin of tumor. of the patients, patients underwent endoscopic treatment and patients underwent transanal excision. no residual tumor was found in additionally removed tissue. there were cases with emr-related complications: early postprocedural bleeding and postpolypectomy syndrome. there was no significant bleeding requiring blood transfusion or perforations. conclusion: endoscopic mucosal resection is considered to be a relatively safe and useful method for treatment of small rectal carcinoids in selected patients. background: disturbance of sexual function after an operation for rectal cancer has often occurred. the relationship between autonomic nerves and arteries in pelvis was examined. methods: clinical studies of male patients with resected rectal cancer were performed using snap gauge method, penile-brachial index and evoked bulvo-cavernous reflex. in canine experiments, pelvic splanchnic nerve (psn) electric stimulation, arterial flow measurement, corpus cavernosum pressure measurement and muscle strip study using drugs were evaluated. results: in clinical studies of male patients, transection of the hypogastric nerve (hgn) and the sympathetic trunk did not affect the erectile function in the postoperative course. in animal experiments transection of these nerves did not affect the increase in inner pressure of the penis cavernosum. in postoperative cases in which only one side of the lower grade branches of the psn (s ) were preserved, the erectile function was preserved. in animal experiments in which the psn of one side was disturbed, the ipa flow of the same side decreased, while the flow of the other side increased. we have evaluated the role of adrenergic components in the psn on the erectile function in the dog. the effect of norepinephrine hydrochloride on canine vascular smooth muscle was examined in vitro. vascular smooth muscle strips from the ipa relaxed longitudinally. electrical stimulation of the psn increased blood flow in the ipa and also elevated the cavernous pressure. these increases were blocked in part by phentolamine, but not by propranolol or atropine. the effects of cholinergic and adrenergic agonists and antagonists on mechanical responses were also examined in muscle strips obtained from various arteries in the intra-pelvic region including the ipa. norepinephrine induced contraction in the iliac artery and relaxation in the ipa, and both the contraction and relaxation responses were blocked by phentolamine but not by propranolol. these findings suggest that in the dog, α-adrenergic components projected through the psn may contribute to penile erection. conclusion: blood flow in the ipa was controlled significantly by the same side psn, but compensatory by the other side psn. it is also conceivable that the erectile function through the psn is controlled by the sympathetic nerve, not by the parasympathetic nerve. in postoperative cases in which only one side of the lower grade branches of the psn (s ) were preserved, the erectile function was preserved. introduction: currently, neoadjuvant chemo-radiotherapy (ncrt) followed by low anterior resection or abdominoperineal resection are the standard treatments for locally advanced rectal cancer. ncrt can improve resecability, achieve better sphincter preservation and reduce local recurrence. although total mesorectal excision is the standard treatment for advanced rectal cancer, recent trends in minimally invasive treatments led to an increase in local excision or "watch and wait" in patients with an excellent response to ncrt. the purpose of this study, part of an ongoing research, is critically evaluating the feasibility of "non-operative treatment" for rectal cancer in a district hospital. methods and procedures: a total of patients with rectal cancer, who where treated with ncrt from january to august at "carlo urbani" district hospital in jesi (italy), were retrospectively reviewed. all patients had histologically-confirmed primary adenocarcinoma of the rectum located within cm from the anal verge. the involved patients completed ncrt and had no recurrence disease, distant metastasis, synchronous malignancies. they were classified according to the mandard's tumor regression grade (trg) into two clusters: group a (trg - ) and b . results: the average age of people is . and were male. five patients underwent abdominoperineal resection and % fell within group a. six patients had lymph nodes involved. four patients suffered relevant complications, such as wound complication, anastomotic leak, operative reintervention and death. univariate analysis showed that the main predictors of tumor regression were the absence of lymph-nodes involvement from initial imaging (p. ), normal initial carcinoembryonic antigen level (p. ) and tumor downstaging in imaging (p. ). in addition, most relevant complications occurred to elderly patients although they observed a good clinical response. besides, % of patients were found to be complete pathologic responders upon examination of the surgical specimen. conclusions: the oncologic feasibility of non-operative management for the patients with complete clinical response after ncrt has been growing, but some studies have suggested lack of oncologic safety in these patients. the patients with a complete clinical response expect good survival, but they may still harbor residual disease. no consensus on "watch and wait" policy in the field of rectal cancer was obtained, yet. our data did not entirely support this policy although it might be the best strategy, based on the predictors of tumor regression, to avoid the complications associated with surgery in elderly patients with significant medical comorbidities and fear of a permanent stoma. introduction: conventional incision laparoscopic surgery procedure for rectal cancer is widely accepted as a successful alternative to laparotomy now, bestowing specific advantages without causing detriment to oncological outcome. evolving from this, single-incision laparoscopic surgery (sils) has been successfully utilized for the removal of colonic tumors, but the literature lacks sufficient data analyzing the suitability of sils for rectal cancer especially for total resection mesorectal excision (tme), particularlyon oncological outcome. we report the short-term clinical and oncological outcomes from a large cases retrospective analysis of observational study of sils for tme procedure of rectal cancer. methods: rectal cancer patients who underwent transumbilical single incision laparoscopic tme surgery were recruited in the current study. short-term perioperative clinical parameters and oncological outcomes were observed and all patients were followed up after surgery. then summarize the preliminary application results. results: operations were accomplished successfully with single incision laparoscopy, patients were converted to multiport approach, and was converted to laparotomy, no diverting ileostomy was performed. the average operative time was ( . ± . ) min, with an average blood loss of ( . ± . ) ml, the median postoperative hospital stay was ( . ± . ) days. all patients received a r resection and the surgical margin were conformed negative in all cases, the median number of harvested lymph node is ( . ± . ), the specimens met the requirement of tme. there were postoperational complications, no operation-related mortality or postoperative anastomotic leakage was observed. no patient appeared recurrent in a median follow up of months. conclusions: total mesorectal excision surgery for rectal cancer can be safely performed using transumbilical single incision laparoscopic technique, with acceptable short-term clinical and oncological outcome. surg endosc ( ) background: any surgical trauma induces an inflammatory response, which is considered as a negative factor in the general immune response, specially in malignant disease. the c-reactive protein (crp) is an acute phase protein often used as a marker of surgical trauma. stent treatment has been used as a treatment option for colonic obstruction in palliative cases for many years, and also as a bridge to surgery in selected cases. in a pilot study we compared the inflammatory response after acute stent treatment or surgery for malignant colonic obstruction. method: we compared two consecutive series of treatment of acute malignant colonic obstruction, stent treatment or emergency surgery during - . all patients were admitted with acute colonic obstruction due to colorectal cancer. choice of treatment was based on attending senior colorectal surgeons' preference, patient comorbidities and disseminated disease was considered. patient age, crp, time to first defecation and length of stay was recorded. results: a total of patients were identified in a retrospective analysis. patients had acute stent treatment and had acute surgical treatment for colonic obstruction, all due to colorectal cancer. median age was y ( - ) with no difference between the groups. there was no difference in metastatic disease between the groups. median time until first defecation after treatment was significantly shorter for the stented patients ( h ( - )) compared with those operated ( h ( - )) (p, ). median hospital stay was also shorter in the stent group, days ( - ), versus days ( - ) in the surgical group (p= , ). crp did not differ between the groups before treatment. both treatments resulted in increased crp levels at postoperative days and , but the crp levels were significantly higher in the surgical group than in the stent group at both time points (pod p= , , pod p, ) conclusion: acute stent treatment in colonic malignant obstruction seems to induce a less pronounced inflammatory response compared with surgery, as shown by a significantly reduced increase in postoperative crp resulting in shorter time to first defecation and a shorter hospital stay. introduction: meckel's diverticulum is the most common congenital abnormality in newborns, present in about - % of them. diagnostic of meckel's diverticulum requires a high index of suspicion, and even with the use of modern imaging technologies, they are often diagnosed intraoperatively. what to do when an asymptomatic diverticulum is found incidentally during surgery for other causes is a matter of discussion. objective: the aim of this article is to report symptomatic and asymptomatic incidentally found cases seen in a fourth-level hospital in colombia. the reports of the histopathologic examinations carried out in the hospital in the last years were reviewed searching for those containing meckel's diverticulum in their diagnosis. patients were divided in asymptomatic and symptomatic groups. the asymptomatic group was defined as patients who were operated for a different indication and a meckel's diverticulum was found incidentally. morbidity was divided in early and late complications after the initial surgery. results: from january to june , a total of pathology reports included the diagnosis meckel's diverticulum. a total of adult patients were retrieved. all of those patients with meckel's diverticulum a total of patients were symptomatic, being sbo the most common complication and required the surgical remove incidentally. conclusion: the correct approach of the patients with diverticular pathology allows the early identification and the appropriate management of the surgical complications that can be presented. robert j czuprynski, md, grace montenegro, md; saint louis university hospital presacral masses are a rare entity, with an incidence of . % and can be classified in several categories, including inflammatory, neurogenic, congenital, osseous and miscellaneous. in this case, a neuroendocrine tumor was identified with concern for iliac chain lymphatic and gluteal metastasis. the patient underwent abdominoperineal resection, excision of presacral mass, lymph node biopsy and omental flap. final pathology returned as a grade ii neuroendocrine tumor arising from a tailgut cyst. a year old female with a ten year history of recurrent perianal, ischiorectal and deep postanal abscesses presents with a presacral mass biopsy proven well-differentiated neuroendocrine tumor. octreotide scan demonstrated avidity for presacral mas as well as left intergluteal lymph node and two internal iliac lymph nodes. chromogranin a, neuron-specific enolase and serotonin markers were all negative. the patient was taken to the operating room and underwent abdominoperineal resection, resection of presacral mass and internal iliac nodes with an omental flap. neuroendocrine tumors arising from tailgut cysts of the presacral space are rare in nature. in a retrospective study from great britain, four of thirty one tailgut cysts had malignant transformation, so it is generally recommended to resect the cysts. in this case, the patient's tumor was a moderately differentiated, grade ii with extensive lymphovascular and perineural invasion. there are no prospective studies showing neoadjuvant therapies in neuroendocrine tumors of the presacral space. according nccn guidelines, patient is currently asymptomatic with low tumor burden. recommended treatment at this time is observation with surveillance tumor markers every - months or octreotide. anastomotic leakage has been commonly regarded as one of the toughing postoperative complications in laparoscopic mid/low rectal cancer surgery, attenuating the short-term clinical benefits. the left colic artery (lca) has been routinely central-ligated in dissection process to guarantee the oncological effects, which may potentially attribute to the postoperative ischemia-induced anastomotic leakage in the patients with left-colic vessel variation, e.g. bypass or absent of riolan arch. however, no specific study focuses on the surgical benefits of lca preservation compares to conventional ones. herein, we conduct a single center randomized controlled trial, demonstrating that lca-preserving technique shows significant reduction rate of postoperative leakage as well as overall complications comparing to the traditional central-ligation group. no difference in survival rate and recurrence in short term is found between the two groups. the lca-preserving strategy is proven to be repeatedly safe and feasible, potentially reduce the risk of anastomotic leakage with comparable short-term outcomes. further investigation is required for both the oncological safety and long-term prognosis for this innovative technique. background: three-photon imaging (tpi), which was based on the field of nonlinear optics and femtosecond lasers, has been proved to be able to provide the -dimensional ( d) morphological feature of living tissues without the administration of exogenous contrast agents. the purpose of this study is to investigate whether tpi could make a real-time histological d diagnosis for colorectal cancer compared with the gold standard hematoxylin-eosin (h-e). methods: this study was conducted between january and august . a total of patients diagnosed as colon or rectum carcinoma by preoperative colonoscopy were included. all patients received radical surgery. the fresh, unfixed and unstained full-thickness cancerous and the corresponding normal specimens in the same patient, were immediately prepared to receive tpi after surgery. for d visualization, the z-stacks were reconstructed. all tissue went through routine histological procedures. tpi images were compared with h-e by the same attending pathologist. results: the schematic diagram of tpi is shown in fig. a . peak tpi signal intensity excited at nm was detected in living tissues. the field of view (fov) was µm and the imaging deep was µm in each specimen. in normal specimens, glands lined regularly and characterized as a typical foveolar, which was comparable to h-e images ( fig. b and d ). in cancerous specimens, irregular tissue architecture and shape were identified by tpi, which was also validated by corresponding h-e images ( fig. c and e ). tpi images can be acquired with a view of d visualization. based on rates of correlation with pathological diagnosis, the accuracy, sensitivity, specificity, positive predictive value, negative predictive value were %, %, %, %, . %, respectively. conclusions: it is feasible to use tpi to make a real-time d optical diagnosis for colorectal cancer. with the miniaturization and integration of colonoscopy, tpi has the potential to make a real-time histological d diagnosis for colorectal cancer in the future, especially in low rectal cancer. erica pettke , abhinit shah , vesna cekic , daniel feingold , tracey arnell , nipa gandhi , carl winkler, md , richard whelan ; mount sinai west, columbia university introduction: alvimopan (alvim) is a peripherally acting µ-opioid receptor antagonist used to accelerate gastrointestinal functional recovery postoperatively (postop) after bowel resection. the purpose of this retrospective study was to compare the time to first flatus and bowel movement (bm) as well as length of stay (los) following elective minimally invasive colorectal resection (crr) in a group of patients (pts) who received alvimopan perioperatively (periop) vs a group that did not get this agent. methods: a data review from to from irb approved databases was carried out. operative, hospital and office charts were reviewed. routine use of alvim for elective crr cases was stared in . besides gi data, preoperative comorbidities and day postop complication rates were assessed. the results with periop alvim were compared to a no-alvim group. the students t and chi-square tests were used. results: a total of pts underwent elective crr. alvim was administered periop to pts ( %). the breakdown of indications between groups were similar. alvim pts were younger ( . vs. . years old, p= . ) and, as regards comorbidities, less likely to have heart disease (cad . % vs . %, other heart disease . % vs . %) but were otherwise similar. the rate of laparoscopic-assisted (alvim, . %; no alvim, %) and hand assisted or hybrid operations (alvim, . %; no alvim, %) were similar. alvim pts had significantly earlier return of flatus ( . vs . days) and first bm ( . vs . , p. for both) than the no alvim group. there was also a trend toward a shorter los ( . vs . days, p= . ) for the alvim group. overall complication rates were similar, however, alvim pts had lower rates of post-operative ileus ( . % vs . %, p. ), sssi's ( . vs %, p= . ), and blood transfusion ( . vs . %, p= . ) than the no alvim group. conclusion: the two groups compared were largely similar (most co-morbidities, indications, crr type) with the differences in age and cardiac issues noted. the impact of the higher rates of sssi's, blood transfusion, and mi in the no alvim group on gi function is unclear. pts who received alvim periop had an accelerated return of bowel function, decreased postoperative ileus and shorter length of stay. these results suggest that alvim is effective in reducing the postoperative ileus but further study is warranted. background: laparoscopic total proctocolectomy (tpc) is selected for minimally invasive surgical treatment of familial adenomatous polyposis (fap) and ulcerative colitis (uc). our policy of tpc is no diverting ileostomy for fap and creating ileostomy for ibd because most of the patients received steroid therapy. objective: we examined the outcome of laparoscopic tpc according to disease of fap and ibd (uc and crohn's disease). methods: twenty-three consecutive patients who underwent laparoscopic tpc between april and march were examined. the patients were divided into fap group and ibd group. results: seven patients of fap and patients of ibd (uc , crohn's disease ) underwent laparoscopic tpc or total colectomy. among them, patients (fap , ibd ) were cancerassociated cases. the procedures of the fap group was tpc with iaca in patients and hals total colectomy with ira in patient. the procedures of ibd group were tpc with iaca in patients, tpc with iaa in patients, total colectomy with ira in patients, of which hals cases. the mean operative time and blood loss were minutes, . g in the fap group and minutes, . g in the ibd group, respectively. diverting ileostomy was constructed in patients of only uc group. early complications of fap group were observed in cases (postoperative ileus , anastomotic leak with conservative treatment ), and those of ibd were observed in cases (ileus , anastomotic leak with conservative treatment , abdominal abscess , wound infection ). the median postoperative hospital stay was days in the fap group and days in the ibd group. complications requiring reoperation were cases (fap : intestinal obstruction, ibd : inflammation of stoma-closure site). no cancer recurrence and mortality were observed. one case of fap underwent additional transanal mucosal resection due to new lesion of adenoma. conclusions: laparoscopic total proctocolectomy for fap and ibd was performed safely, especially less complications occurred in fap patients without diverting ileostomy. in addition, followup of remaining mucosa is important in iaca and ira patients. treatment of complex anal fistula has always been a nightmare for surgeonsby conventional means. even the lowest and simple looking fistula at times comes out to be a complex one with high incidence of recurrence above %. most of the availability diagnostic including mri is nit conclusive and many a times the surgeon remains in a state of confusion as to what is going to come at the operation table. the conventional treatment modalities also usually leave the patient wounded needing almost to weeks to heal with a risk of sphincter damage and a high risk of recurrence. we would be presenting the technical details and results of our series of cases of complex anal fistula treated by video assisted endoscopic therapy. jun higashijima, phd, mitsuo shimada, professor, kozo yoshikawa, phd, takuya tokunaga, phd, masaaki nishi, phd, hideya kashihara, phd, chie takasu, phd, daichi ishikawa, phd; department of surgery, the university of tokushima background: one of the important causes for anastomotic leakage (al) in anterior resection is an insufficient blood flow of the stump. the hems (hyper eye medical system) and spies (laparoscopic icg system) can detect the blood flow of fresh organ intraoperatively by injection of indocyanine green (icg). and thermography also can evaluate the bloodflow less invasively. the aim of this study is to evaluate the usefulness of icg system and thermography in laparoscopic anterior resection. patients and methods: this study retrospectively included patients who underwent laparoscopic anterior resection for colon cancer with double stapling anastomosis procedure. blood flow evaluation of oral stumps was performed with measurement of fluorescence time (ft) using hems and spies. and bloodflow was also evaluated by thermography. result: evaluation by icg system: in all cases, the al rate was . % ( / cases). over ft cases, the al rate was %, higher than that of under s cases and these patinets need additional management, covering stoma or additional resection. and in border cases, ft * sec, al rate is . %, higher than under s cases. in these borderline cases, if covering stoma was performed in patinets with more than three well known risk factors, the al rate reduced to . % and false positive was . %. and under s cases, they need no additional management. evaluation by thermography: in residual intestine, the temperature was siginificantly higher than resected intestine ( . vs . ?, p. ). and the temperature in ft under s cases was significantly higher than over ft over s cases ( . vs . ?). the temperatue and ft was tended to be oppositely correlated (r = . ). conclusion: both icg system and thermography may be useful to avoid anastomotic leakage. introduction: some patients who undergo neoadjuvant chemoradiation therapy (crt) for rectal cancer achieve a pathologic complete response (pcr) in which no tumor cells are discovered during pathologic analysis of the resection specimen. achievement of pcr is correlated to improved prognoses relative to non-pcr counterparts. such correlations are not well established in the context of a community-based hospital. the study sought to examine response rates, recurrences, and survivals in locally advanced rectal cancer patients and compare patient outcomes to those achieved at major academic institutions. methods and procedures: a single-center retrospective chart review was performed at a local, community-based hospital. study population consisted of patients with locally advanced rectal cancer treated with neoadjuvant crt followed by surgical resection. patients with a history of metastasis, inflammatory bowel disease (ibd), hereditary cancer syndromes, concurrent or prior malignancy, and emergent surgery were excluded. results: patients ( . %) achieved pcr in the test population. across both groups, mean age (p =. ), gender (p=. ), and ethnicity (p=. ) were found to be comparable. mean interval between crt and or (p=. ), pre-op stage (p=. ), number of nodes (p=. ), radiation dose (p=. ), tumor location (p=. ), and days of follow-up (p=. ) presented statistically insignificant differences between groups. at years, non-pcr patients ( . %) had a recurrence with zero recurrences in the pcr group. -year mortality presented non-pcr patients ( . %) compared to pcr patient ( . %). conclusion: a multidisciplinary approach to rectal cancer consisting of standardized preoperative treatment and surgical resection can achieve patient outcomes and survival similar to those of larger academic institutions, even in the context of a community-based hospital. objective: the aim of this study was to assess safety and feasibility of total mesorectum excision (tme) within the holy plane based on embryology for rectal cancer. methods: prospectively collected data of consecutive patients with rectal cancer who underwent tatme from november to august were enrolled. surgical outcomes including tme completeness, operative time for tme completion, blood loss, complications, pathological findings and length of hospital stay were assessed. surgical procedure: after performing ractal lavage, self-retaining anal retractor was set, and anal dilators were used for an atraumatic introduction of the transanal access devise (gelpoint path). three of -mm trocars and one of -mm trocar were inserted through the gelpoint path in a quadrant shape. then the gelpoint path was introduced through the anal to rectum. after rectosigmoid colon was temporally clamped using an atraumatic endo bulldog clip, pneumoperitoneum was maintained at mmhg with carbon dioxide via an air seal platform. a purse-string suture using a polypropylen with -mm rounded needle was performed clock-wise to tightly occlude the rectum with a cm margin distal to the tumor. after irrigation with saline and marking dissection line with tattooing the rectal mucosa distal to the mucosal folds, a mucosal transection of rectum was initiated. then a full-thickness rectal transection was performed circumferentially. after dissection of rectococcygeal muscle at o'clock and rectourethral muscle in the anterior wall, circumferential sharp dissection within the holy plane was performed. dissection proceeded between the endopelvic fascia and the prehypogastric nerve fascia in the posterior plane, between the denonvilliers's fascia and the anterior mesorectum in the anterior plane, and between pelvic nerve and the mesorectum with recognition of the neurovascular bandle in the lateral plane. then the dissection connected to the abdominal plane via laparoscopic team with working together until tme completed. results: tme completion performed in ( . %) patients. thirty five ( . %) patients had negative of circumferential resection margin. mean of tme completion time and blood loss were min and g, respectively. one ( . %) patient had an intraoperative complication and ( . %) patients had postoperative complications. no other complications occurred. the length of hospital stay was days. conclusions: tatme within the holy plane on based on embryology is a safe and feasible procedure for rectal cancer. abstract: acromegaly is a debilitating condition marked by excessive production of growth hormone. this leads to disfiguration, cardiopulmonary complications, and increased risk for cancer. with up to a two-fold increased risk of developing colon cancer and worse prognosis for diagnosed patients, earlier and more frequent screening has been recommended. we present a case of a -year-old hispanic male with acromegaly who presented to our hospital with hematochezia and weight loss. a near-obstructing rectal adenocarcinoma with metastasis to the liver was discovered. after completing neoadjuvant chemoradiotherapy, he underwent laparoscopic low-anterior colon resection and simultaneous open hepatic trisegmentectomy. in this case report, we review the literature and current guidelines in screening this high-risk group of patients. introduction: in this study, we discovered that in cme for laparoscopic right hemi-colectomy starting at the ileocolic vessel and proceeds along the superior mesenteric artery (sma) achieved a better oncologic outcome compared with the conventional ones proceeding along the superior mesenteric vein (smv). methods and procedures: patients admitted to a shanghai minimally invasive surgical center were included from september to january and were randomly divided into two groups: study group (n = ) and conventional group (n = ). operation time, blood loss during surgery, liquid intake time, postoperative hospital stay, postoperative complications within days after surgery, specimen length, and number of lymph nodes harvested as well as the positive lymph node rate were observed and studied. results: there was no statistical difference between the two groups with the exception of number of lymph node dissected and the positive lymph node rate for stage iii colon cancer. the study group had more lymph node retrieved and also a higher positive rate compared with the conventional group. the mean number of lymph node retrieved of study group was . ± . , while the conventional group was . ± . (p. ). and the positive lymph node rate for study group was . %, the conventional group was . %. conclusion: when performing the laparoscopic right hemi-colectomy, dissecting the lymph node along with the left side of sma could be achievable and there were no differences of surgical outcomes compared with the conventional ways, while there was a higher number of lymph nodes dissected and positive rate probably leading to a better oncologic outcome. aims: we describe laparoscopic surgery for rectal cancer using needlescopic instruments performed at our department. methods: from to , cases of rectal cancer underwent surgery using needlescopic instruments: cases at rectosigmoid colon, at upper rectum, and at lower rectum. an umbilical camera port ( -mm) and two needlescopic instruments (endorelieftm) were directly punctured into the assistant surgical site. we started with port sites. in low rectum cancer cases, we kept the good pelvic visualization to lifting the peritoneum of the bladder onto the ventral side using the lone star retractor staystm. results: the median age was years ( - years), with males and females, and body mass index was . kg/ m ( - kg/m ). anterior resection was performed in cases, low anterior resection in cases, intersphincteric resection in cases, abdominoperineal resection in cases, hartmann's procedure in cases, and lateral lymph node dissection in case. in addition, one case of t b (bladder) was converted from laparoscopic to open surgery. however, there were no cases in which needlescopic instruments were replaced with conventional forceps. moreover, intraoperative complications related to the forceps were not observed. conclusions: in rectum cancer surgery, needlescopic instruments leave a small postoperative wound; healing is rapid and the cosmetic result is excellent. surgical safety is comparable to that using conventional forceps. there is no problem with the rigidity of needlescopic instruments. however, where the shaft is curved, operative control requires attention to mobility and directionality. in low rectum surgery, use of needlescopic instruments is limited due to the curvature of the shaft during the dissection of the anterior rectum wall, but it is possible to maintain a good field of view by using auxiliary equipment. therefore, more cases could be considered for surgeries using needlescopic instruments with the help of auxiliary equipment. introduction: anastomotic leaks are devastating complications of colorectal operations that lead to significant morbidity and potential mortality. inadequate tissue perfusion is considered a key contributor to anastomotic failure following colorectal operations. currently, clinical judgment is the most commonly used method for evaluating adequate blood supply to an anastomosis. more recently intraoperative laser angiography using indocyanine green (icg) has been utilized to assess tissue viability, particularly in reconstructive plastic surgery. this technology provides a real-time evaluation of tissue perfusion and is a helpful tool for intra-operative decisions, particularly in deciding to revise an intended colorectal anastomosis. our study aimed to determine if there is a statistical significance in colorectal anastomotic leak or abscess rate using icg compared to common clinical practice. methods and procedures: patients undergoing left-sided colorectal operations, between march and february , were retrospectively reviewed. patients' colorectal anastomoses were evaluated using icg angiography (icga) to qualitatively assess tissue perfusion (icg group). peri-operative and post-operative outcomes, including anastomotic leak and abscess rates, were compared to patients who had colorectal operations without icga (control group). the primary outcomes of intra-abdominal leak rate and intra-abdominal abscess rate were compared using exact chi-square tests. the secondary outcomes of -days or return, mortality, and readmission rate were compared using chi-square tests. all statistical analyses were performed using sas software. results: two leading indications for surgery included malignancy (n = ) and diverticulitis (n = ). the majority of patients either had a low anterior resection (n = ) or sigmoidectomy (n = ). all operations were primarily minimally invasive. no statistically significant difference was seen between the two groups in regards to patient demographics, rate of proximal diversion (p = . ), and splenic flexure mobilization (p = . ). patients in the icga group were more likely to have high ima ligation than in the control group ( . % vs. . %, p-value. ). of the icga group, of the patients underwent additional colonic resection while of the did not undergo additional colonic resection. there was no statistically significant difference in primary or secondary outcomes between the two groups. conclusion: icg angiography has become a helpful adjunct in determining adequate perfusion to an intended colorectal anastomosis. this data is unable to support any difference in patient outcome utilizing this technology over surgeons' visual and clinical assessment. our results may contribute to larger studies to determine if there is a true difference in anastomotic leak or abscess rate using this technology. objective: to investigate the feasibility and surgical strategy of complete mesocolic excision (cme) with completely medial access by "page-turning" approach (cmapa) for the laparoscopic right hemi-colectomy. the cmapa is a modified medial approach of cme, which focus on the exploration of surgical plane instead of the recognition of vessels. surgical procedures: ( ) start point: the anatomy projection of ileocolic vessel; ( ) expose the whole trunk of smv to the level of inferior edge of pancreas before ligating any branches, for the purpose of high tie and verifying their location; ( ) enter the intermesenteric space (ims) and right retrocolic space (rrcs) with cranial and right extension through transverse retrocolic space (trcs); ( ) complete mobilize the mesocolon and remove the tumor en-bloc. see figure ? . clinical outcome: from september to march , there were patients underwent cmapa in shanghai ruijin hospital. the average operation time was . ± . minutes, average blood loss was . ± . ml, number of lymph node was . ± . , average specimen length was . ± . cm, flatus time was . ± . days, fluid intake time was . ± . days and average hospital stay was . ± . days. the overall complications rate was . % ( / ). compared to traditional medial approach of cme performed in our center, the blood loss, operation time and hospital stay were significantly reduced by performing cmapa for laparoscopic right hemi-colectomy. conclusion: the advantage of the cmapa ( ) to avoid the laparoscopic "leverage effect" and "tunnel effect". ( ) to make the branches of superior mesenteric vessels more easily recognized. ( ) to offer surgeons an alternative route entering the trcs, ims and rrcs. ( ) to avoid repetitive flipping of the colon complying with the "no touch" principle, and to lower the requirements of assistants. figure : anatomy and surgical planes concerning cmapa. aim: we have reported a possibility of "one-stop shop" simulation for liver surgery by mri using gadoliniumethoxybenzyl-diethylenetriamine pentaacetic acid (eob-mri) (emerging technology, sages )., which is characterized by ( ) one-time examination, ( ) no-radiation exposure, ( ) demonstration of liver vasculatures including biliary tract, ( ) diagnosis of tumors, ( ) volumetry and ( ) estimation of liver functional reserve in each segment. the aim of this study is to investigate usefulness of "one-stop shop" simulation for liver surgery using eob-mri. methods: accuracy of liver vasculatures: d-reconstruction of dynamic eob-mri imaging was done by synapse vincent software (fujifilm medical co., ltd., japan), using a manual tracing method. visualization of hepatic vessels in eob-mri was compared with that in dynamic ct in patients. assessment of liver functional reserve: the standardized signal intensity (si) of each segment was calculated by si of each segment divided by si of the right erector spine muscle. the standardized total liver functional volume (tlfv) was calculated by ∑ [k= to ] (standardized si of segment (k) volume of segment (k)) divided by body surface area. the following formula of resection limit was established using normal liver cases ( % of the liver is resectable) and unresectable cirrhotic patients such as recipients of liver transplantation ( % of the liver is resectable). the estimated resection limit (%)= % (the standardized tlfv of the patient - )/ , . this formula was validated using other patients who underwent hepatectomy. results: accuracy of liver vasculatures: the liver simulation by eob-mri succeeded in demonstrating hepatic vasculatures including biliary tract, diagnosis of hepatic tumors, and volumetry without any radiation exposure. regarding the vessel anatomy at hilar area, biliary tract was more clearly visualized in eob-mri. regarding the hepatic artery, right and left hepatic arteries were well visualized in all cases, however, small-sized middle hepatic artery was visualized in only one out of patients. assessment of liver functional reserve: as a result of validation of the patients, one patient having resection volume with over the resection limit died of liver failure, however, the other cases within their resection limits did not suffer from liver failure. conclusion: "one-stop shop" liver surgery simulation could contribute to safety of liver surgery such as laparoscopic hepatectomy, because of no radiation exposure, accurate assessment of anatomical variations especially biliary tract, and helping decision making of resection volume. showing key steps of the procedure to be viewed. the in-studio program was hosted by an education specialist from the science center and a surgical resident from our institution, with laparoscopic instruments available for manipulation by participants. participants then viewed a video highlighting the roles of all healthcare providers involved in the specialty to be featured, including nurses, physicians, dietitians, psychologists, technologists, etc. live questions and answers were then encouraged between students and surgeons during the surgery broadcast. the program also expanded from high schools to vocational-technical colleges and nursing schools. results: during the - academic year there were sessions presented to schools, with student participants. by the - year this increased to sessions presented to schools, with participants. in sum, throughout the first years of the program, there were schools attending, with a total of , participants. of polled high school participants, % of responders acknowledged considering a career in healthcare after this experience. conclusion: over years, our program has grown steadily in popularity such that schools from several counties attend and regularly return, and we have been asked to expand the program to create a surgical summer camp for students interested in science and technology. live broadcast surgery in an elective, minimally invasive format provides unique visibility and access to surgical procedures for student audiences and promotes future interest in healthcare careers. surg endosc ( ) :s -s p improving trainees' self-assessment through gaze guidance introduction: effective learning to become competent in surgery depends on a trainee's ability to accurately recognize their strengths and weaknesses. however, a surgical trainee's self-assessment is poorly correlated with expert assessment. this study aimed to improve self-assessment by the visual gaze guidance provided through telestration in laparoscopic training. we hypothesized that visual conveyance of where to look or perform actions on the laparoscopic video enhances the trainees' awareness of the gaps in their skills and knowledge. methods and procedures: a lab-developed telestration system that enables the trainer to point or draw a free hand sketch over a laparoscopic video was used in the study (fig. ). seven surgical trainees ( surgical fellow, research fellow, pyg- and pyg- ) participated in a counterbalanced, within subjects controlled experiment, comparing standard guidance with telestration-supplemented guidance. the trainees performed four laparoscopic cholecystectomy tasks -mobilizing cystic duct and artery, clipping the duct, clipping the artery, and cutting the duct and artery, on a laparoscopic simulation. performance assessment, adapted from the global rating scale (grs) instrument, was completed by the trainers and trainees at the end of each task. the mean self-assessment scores were compared with the trainers' scores by the linear mixed model, where the trainees' performance indicated by the trainers' scores was control. the assessment alignment was evaluated by spearman's rho. results: the trainers' scores were significantly lower than the self-assessment scores in the standard guidance, while the scores of the trainers and trainees were much more similar (fig. ) . the correlation between the trainers' and trainees' assessment in telestration guidance was high (r= . , p. ), compared to the standard guidance (r= . , p= . ). the correlation comparison for each grs criterion shows a significant increase (p= . ) in the assessment alignment for depth perception in telestration guidance (r= . , p. ), compared to the standard guidance (r= . , p= . ) (fig. ) . the visual gaze guidance improved the alignment of assessment between the trainer and trainees, especially for the assessment alignment in depth perception. for visual gaze guidance to become an integrated part of the training, further work needs to be conducted to understand how gaze guidance change the nature of the training process. applying to surgical residency: what makes the best candidates? yann beaulieu, beng, louis guertin, md, frcsc, ariane p smith, md, margeret henri, md, frcsc, facs; university of montreal objective: while quotas for canadian surgical residency programs are at their lowest point in ten years, the number of canadian graduating medical students is at an apogee. this year, only spots in surgical residency programs were available for students applying to carms. undergraduate medical students individually collect anecdotal information regarding what influences admission to their surgical subspecialties of interest, as scarce literature covers the topic. we thus surveyed surgeons and residents to analyze the relative importance of modifiable factors and innate attributes in the selection of new surgical residents. methods: an electronic survey was sent to all surgeons and surgical residents affiliated with the university of montreal. participants were asked to specify their surgical subspecialty, their status, their level of experience and whether they were an active member of a residency selection committee. the subjective importance of predefined application elements and candidate qualities was assessed using -point likert-type items. results: of the surgeons and residents to whom the survey was sent, ( . %) and ( . %) completed the survey. evaluations of elective rotations and evaluations of core rotations were considered very important by . % and . % of responders respectively. regarding letters of recommendation, the content was rated very important ( . %) more often than the notoriety of the author ( . %). networking with key surgeons was considered the least important element to prioritize with % of negative assessments. with regards to the fundamental qualities of surgical candidates, the extremes were "clinical judgement" with . % and "innate technical ability" with . % of responders rating them very important. no significant differences in responses were observed between staffs and residents, between members and non-members of selection committees, between different levels of surgical experience and between surgical subspecialties. conclusion: clinical judgement and performance in core and elective rotations along with strong personalized letters of recommendation should be prioritized by medical students aiming for a surgical career. kazuhiko shinohara, phd, md; school of health science, tokyo university of technology background and objective: many types of training devices had been proposed since the early days of endoscopic surgery. however, they are too expensive for daily training of novices. we developed a simple and economical training device made of frozen fruit and agar. material and methods: to make this device, g of agar powder was added to ml of boiling water and boiled for min. the solution was then poured into a stainless steel tray containing frozen blueberries and lychees and refrigerated for h. basic maneuvers required during endoscopic dissection and resection of a tumor with laparoscopic forceps and electrosurgical devices were then performed using this agar model in a conventional laparoscopic training box. results: using this model, endoscopic dissection and enucleation of a tumor with an electrosurgical device could be practiced repeatedly with minimal expense and preparation. background: situs inversus totalis (sit) is a rare congenital anatomy and a challenging condition for laparoscopic surgeries because standardized strategy to overcome such anatomical difficulties. mirror-reversed video images of laparoscopic surgeries for patients with normal anatomy could help to develop surgical strategies for patients with sit. we had a chance to evaluate this idea with a treatment of a patient of early gastric cancer, and describe the surgical results of the case. patient and methods: seventy-two-year-old women with a history of sit was referred to our department for the treatment of early gastric cancer, and laparoscopic distal gastrectomy with d + lymphadenectomy was scheduled. a video record of the same surgery for a patient with similar physical attribute performed before then was retrieved, and was edited with a computer into full length, totally mirror-reversed images of the surgery. designated operator and assistant simulated the operation using the video several times before surgery. results: laparoscopic distal gastrectomy was performed with d + lymphadenectomy while the operator was on the left side of the patient and the assistant on the other side, being opposite positions as usual. laparoscopic b- reconstruction was followed using "delta anastomosis" technique reported by kanaya et al. total laparoscopic procedures were completed with the operation time of minutes and the blood loss below measurable limits. no appreciable complications were observed after surgery and the patient was discharged on postoperative day . no recurrence of the disease was detected until years after surgery, conclusion: although further validation is unlikely because of a rare incidence of this anatomy, the same technique would be recommended for one of the preoperative preparations for similar cases. background: surgical simulation is thought to provide a basis for improvement of resident surgical skill training, in the safety of a simulation setting. it is unclear whether surgical skills learned in a simulation curriculum actually contribute to the improvement of surgical skills when transferred to the or. methods: a ten question online survey was sent to attending surgeons and residents. the questionnaire focused on domains: confidence, independence, transferable skills, improvement of skills/knowledge and time spent on the simulation curriculum. evaluation data was collected and anonymously analyzed. background: minimally invasive surgery poses a unique learning curve due to the requirement for non-intuitive psychomotor skills. programmes such as the fundamentals of laparoscopic surgery (fls) provide mandatory training and certification for many residents. however, predictors of fls performance and retention remain to be described. this single-centre observational study aimed to assess for factors predicting the acquisition and retention of fls performance amongst a surgically naïve cohort. methods: laparoscopically naïve individuals were recruited consecutively from preclinical years of a medical university. participants completed five visuospatial and psychomotor tests followed by a questionnaire surveying demographics, extracurricular experiences and personality traits. individuals completed a baseline assessment of the five fls tasks evaluated by fls standards. subsequently, participants attended a -minute training-course over week one and two on inanimate box trainers. a post-training assessment was performed in week three to evaluate skill acquisition. participants were withdrawn from laparoscopic exposure and retested at four onemonth intervals to assess skill retention. introduction: bipolar energy can cause thermal injury to adjacent organs when used improperly. sages fuse curriculum provides didactic knowledge on principles and best practices for safety, but there is no hands-on component to practice these skills. the objective of this study is to compare the effectiveness of the vest™ bipolar training module in addition to the fuse curriculum. methods and procedures: the study was a mixed design with two groups, control and simulation. after a pre-test that assessed their baseline knowledge, the subjects were randomized to two groups. both groups were given a min presentation, reading materials from the fuse manual and an online didactic module on bipolar energy. the simulation group also practiced on the simulator for one session that consisted of five trials on the effect of activation time on thermal damage and the importance of providing a margin of safety by sealing short gastric vessels. after one week the performance of both groups was assessed using a post-questionnaire. one week after the post-test both groups performed sealing of vessels on an explanted porcine mesentery with vessels perfused. their performance was videotaped and their activation times were recorded. a total safety score was calculated by assessing the proximity of the location of activation to the intestine by two independent raters. wilcoxon -signed rank and mann-whitney u tests were used to assess difference within and between groups. results: a total of residents ( in each group) participated in this irb approved study. median test scores for both groups increased (simulation, p= . and control, p= . ). no difference was found between the two groups in their pre-test (p= . ) and post-test (p= . ) scores indicating learning. the median total activation time for control group was higher ( . s) compared to simulation ( . s) but was not statistically significant (p= . ). there was a moderate agreement between two raters for margin of safety (kappa= . , p. ). total safety scores showed no difference between the two groups (p= . ). conclusions: subjects with simulation training had lower activation time compared to control. training for margin of safety requires more simulation refinement. small sample size and variations in the explanted models contributed to variability in data but even with small sample size, simulation training along with the fuse curriculum trended towards being more beneficial than the fuse curriculum alone. the general, that aims to build educational infrastructure and standardize training and education in laparoscopy throughout mexico. ilap participants engage in didactic and hands-on modules in educational theory, laparoscopic techniques, and simulation based education (sbe), and then develop and implement a -day sbe course for local trainees. the purposes of this study were to understand the existing educational environment at a single institution in mexico and measure the changes in perceptions, attitudes, and engagement in surgical education after an intensive training course. methods and procedures: all faculty and of general surgery resident participants completed a survey that contained items designed to assess the existing educational environment at a large, public hospital in mexico. using a -point likert scale, residents self-rated the quality of faculty feedback and the learning environment within their institution ( =strongly disagree, = neutral, =strongly agree). faculty rated their perceptions of the same educational themes. upon completion of a faculty-lead simulation course, residents rated the educational environment during the course. faculty provided additional qualitative feedback. descriptive analyses were performed. irb-exemption was obtained through lurie children's hospital. results: discordance existed in perceptions of the existing educational environment. the greatest disparity between resident and faculty perceptions included "faculty provide sufficient feedback in the operating room" ( % vs. %), "faculty promote an active learning environment" ( % vs. %), and "residents may ask questions without fear of negative evaluation" ( % vs. %). faculty and residents agreed with "residents are sometimes afraid to speak up in the operating room for fear of retaliation" ( % each). post-course evaluations (n= ) revealed universal improvement in all educational themes during the simulation course. qualitative feedback revealed most faculty plan to incorporate open communication and safe learning into their practice. residents were equally positive, with % optimistic that they will see changes within the educational environment. conclusions: significant discordance exists in resident and faculty perceptions of the educational environment at a large teaching hospital in guadalajara, mexico. after participation in the ilap course, residents noted demonstrable change in the faculty approach to education and feedback, and both faculty and residents expressed optimism for increased engagement in education. the immediate successes of the ilap initiative should be followed over time, as the ultimate measure of success is sustainability and scalability throughout mexico. background: laparoscopic anterior resection is technically challenging and the learning curve is long. well-designed formative assessments can provide trainees effective and constructive feedback, an important element in efficient learning. previously reported assessments for laparoscopic colorectal procedures were developed for summative assessment. we aimed to develop a formative assessment tool to evaluate competence and provide trainees with effective feedback in laparoscopic anterior resection. methods: the assessment tool was developed by an expert panel from mcgill university affiliated hospitals. the procedure was deconstructed into a series of sequential steps including general domains, surgical principles, injury prevention and technical skills specific to laparoscopic anterior resection. the tool contains discrete items with global rating scales for each step of the operation; each domain was scored using a -point likert scale, with anchors for scores of , and . each operation was assessed through direct observation in the operating-room by the attending, a trained observer, and trainees themselves. intraclass correlation coefficients (iccs) were calculated to estimate interrater reliability for ( ) attending surgeon and trained observer, ( ) attending surgeon and self-assessment, and ( ) trained observer and self-assessment. internal consistency was measured using cronbach's alpha. comparison between training levels was done using mann-whitney u-test. the global operative assessment of laparoscopic skills (goals) was also used to assess trainees' general laproscopic skills. spearman's correlation was used to determine association between goals and this procedure-specific tool. overall usefulness of this tool was evaluated using a cm visual analog scale. results: in this pilot study, fourteen operations, performed by experienced surgeons and trainees were assessed. the icc between ( ) attending surgeon and observer was . ( % ci . to . ) ( ) observer and self-assessment was . ( % ci . to . ), and ( ) attending surgeon and self-assessment was . ( % ci - . to . ). the internal consistency of the items was excellent (cronbach's α= . ). there was a significant difference in median total score between experienced surgeons and trainees ( . ± . vs. . ± . ; p= . ). there was strong correlation (r= . ) between goals and this procedure-specific score. overall usefulness of this assessment tool was rated as . ± . . all assessments were completed in about minutes. conclusions: we present a new procedure-specific formative assessment tool for laparoscopic anterior resection and provide preliminary evidence of its reliability and validity. this formative assessment tool could be used for constructive feedback and tracking performance in competencybased surgical training. cullen introduction: one of the key challenges to the proliferation of endoscopic submucosal dissection (esd) in the west has been a lack of training platforms. therefore, the virtual endoluminal surgery simulator (vess) is being developed as a training tool for esd. the aim of our study is to inform the design of vess using cognitive task analysis (cta), which is a human factors engineering framework to describe practitioners' mental models and cognitive processes and incorporate insights into the simulator's design. methods and procedures: cta-based interview questions were developed to probe the cognitive challenges and strategies employed at each stage of the esd procedure. six esd practitioners were interviewed for varying lengths of time. two of these interviews were conducted simultaneously during an observation of a training workshop where the cta participants were instructors (total observation time was five hours, and interview time was * minutes). another interview was conducted during observation of esd procedures (total observation time was hours, and interview time was * minutes). participants had varying levels of experience in esd, with of them being 'super-experts' (exclusively esd exponents), an 'expert' and a fellow. a cta of the data is currently being conducted to systematically inform design of functionalities in the simulator. results: analysis of our data highlights a few prominent themes at each stage of esd: goals, challenges (e.g., avoiding perforation of muscularis); points of decision-making (e.g., partial or full incision for boundary demarcation); skills involved (e.g., dissection); and ambiguity (e.g., unclear lesion boundaries). participants also described risks associated with each stage of esd and strategies to prevent or overcome the same. conclusions: qualitative data for a cta were collected through observations and interviews of esd practitioners. preliminary analysis has indicated prominent themes to consider in the design of the training simulator. the next step in the study is to conduct a full-scale cta of esd based on the current data. the ultimate benefit of the cta would be to incorporate the results into informing the design of vess in a way that is compatible with the mental models of esd trainees, thus enhancing the fidelity and effectiveness of the simulator. background: colonoscopy is an important diagnostic and therapeutic procedure in the management of colonic disease; achieving competence during residency is an integral part of performing high-quality colonoscopy in-practice, regardless of specialty. there is debate and controversy however, regarding what, if any, number of procedures achieves said proficiency. furthermore, there is significant heterogeneity in the current guidelines and studies published to-date on the definition of competence in colonoscopy. objective: to determine individualized learning curves as an alternative to 'number of procedures' for assessing colonoscopy competence. methods and procedures: this is a multi-institutional prospective cohort study involving eleven surgical trainees (novice endoscopists). the main outcome, colonoscopy competence, was assessed by determining the independent colonoscopy completion rate (iccr), the number of procedures required to reach % independent colonoscopy completion and polyp detection rate. individual and overall iccr were calculated using moving average analysis. conclusions: while a benchmark for a minimum number of procedures may be necessary to allow supervisors to adequately assess performance, it is difficult to determine what number is optimal. there appears to be significant heterogeneity in both overall number of colonoscopies completed by each resident, as well as the mean iccr and the number of procedures required to reach the current benchmark for competency. the use of learning curves allows real-time tracking of progress and training tailored to the individual, as we move forward in the era of competency-based medical education. background: with the growing popularity of robotic-assisted surgery, new methods for evaluation of technical skill are necessary to determine when a surgeon is qualified to perform an operation independently. current evaluation methods are limited to point likert scales which require a degree of subjective scoring. surgeons in training need an objective method of evaluation to view progress and target areas for improvement. one method of objectively evaluating surgical performance is a cumulative sum control chart (cusum). by plotting consecutive operative outcomes on a cusum chart, surgeons can view their learning curve for a given task. another method of objective evaluation is the dv logger®, or "black box," which records objective measurements directly from the da vinci® system. methods: we followed two hpb fellows during dry lab simulation of robotic-assisted hepaticojejunostomy reconstructions using biotissues to model a portion of a whipple procedure. we simultaneously recorded objective measurements of dexterity from the da vinci® system and performed cusum analyses for each procedural step. we modeled each variable using machine learning (a self-correcting and autoregressive modeling tool) to reflect the fellows' learning curves for each task. statistically significant objective variables were then combined into a single formula to create an operative robotic index (ori). results: variables that significantly improved over the course of the simulation included completion time (p= . ), economy of motion in arm (p= . ), number of times head was removed from the console (p= . ), total time left master manipulator was active (p= . ), total time right master manipulator was active (p. ), and total time that any arm was active (p\ . ). the inflection points of our cusum charts and plots of objective variables both showed improvement in technical performance beginning between trials and [ fig. and fig. ]. the operative robotic index showed a strong fit to our observed data and improved with additional trials (r = . ). [ figure ]. conclusions: in this study we identified objective variables recorded by the da vinci® system which correlated with the technical dexterity of fellows during a robotics dry lab. we broke a complex procedure down in stepwise fashion with cusum analyses to determine targets for improvement. using variables which correlated with the improved performance of the fellows, we effectively modeled the learning curve with the creation of an operative robotics index (ori). this study successfully models the learning curve of novice robotic surgeons using a novel combination of objective measures. georg wiese, md, paula veldhuis, steve eubanks, md, facs, scott w bloom, md, frcsc, facs; florida hospital institute for surgical advancement introduction: robotic surgery is a specialized skill which requires time and resources to master. in a general surgery residency program that seeks to train competent surgeons in both open, laparoscopic and endoscopic techniques it is difficult to see where adding robotic training will be of benefit and at what cost this will be to the remaining surgical skills. we therefore sought to ascertain robotic surgery's current role in the training of new general surgeons by soliciting the opinions of current general surgery program directors on the role of robotic surgery at their respective institutions. methods: an irb approved survey was created and sent to general surgery program directors across the country to assess how robotic surgery training is being integrated into current surgical training. the survey was sent via email to publicly available email addresses from the acgme website of program directors. it was voluntary in nature and consisted of questions regarding current status of robotic training in residency as well as future goals. results: overall response from our pd survey were at % of the surgical programs with addresses available via acgme, though responses continue to be submitted at the time of this abstract. approximately % of all respondents are from independent, university based programs. % felt that robotics was an emerging skillset important for residents to master versus % feeling that it was more appropriate for fellowship. all respondents noted that robotic surgeons were present at their institution, % within the core faculty, and % indicated that they were actively recruiting robotically trained surgeons. additionally, % of programs indicated that residents were exposed to robotic surgery, % of these on core general surgery rotations. % of respondents indicated that they had a formal robotic training curriculum with % of programs taking measures to integrate robotics into the future curriculum though % lacked specific milestones for such training. finally, opinion was evenly divided among respondents as to whether one could sign off on residents to perform robotic assisted cases upon completion of pgy year with % agreeing with that statement and the remainder indicating some additional training would be necessary. conclusions: our study highlights the emerging field of robotic assisted mis surgery and its increasing role in residency training. it is evident from the data, that robotic surgery is a growing part of residency experience. importantly, however, milestones were significantly lacking for determining resident progress in robotic training. introduction: in chile, medical students have the opportunity to undertake a month-long medicine elective (me) in a community hospital, primary care center or emergency department within the country at the end of their first clinical year. due to the lack of opportunities to practice suturing in the first years, students usually do not have an optimal performance in this type of medical procedure during the me. simulation training programs in suturing improve technical skills, selfconfidence and patient safety in the medical internship. the objective of this study is to evaluate the impact of implementing a simulated suture training program earlier in the medical curriculum, before the me. methods: we conducted a prospective, randomized controlled trial with medical students at the end of their first clinical year. they were randomized into two equal groups. the intervention group received an intensive suture training program consisting in one theory class, four practical sessions and effective feedback from an expert surgeon. the control group did not receive training, remaining with the classic opportunistic learning approach during the me. after the me, all students undertook an electronic survey. statistical analysis was performed on the answers of both groups. per protocol analysis was applied. results: there were no statistical differences between groups in terms of age and sex. four students did not complete the training program. one student in the control group did not reply to the survey. higher self-confidence with regards to suturing was reported in the intervention group in comparison with the control group [ / ( %) vs / ( %), p, ]. also, a greater student desire to carry out suture-related procedures was reported in the intervention group than the control group [ / ( %) vs / ( %), p, ]. in addition, a lower rate of overseeing physician intervention was reported in the intervention group [ / ( %) vs / ( %), p, ] ( table ) . a greater number of patients requiring sutures were treated by the intervention group than the control group, with a median of patients ( - ) against ( ) ( ) ( ) ( ) . the intervention group performed a higher number of sutures with a median of ( - ) vs ( - ), with a statistically significant difference (p, ) in both cases (fig. ) . conclusion: a simulated suture training program prior to the me generates a positive impact on medical students by improving self-confidence and desire to attend patients that require sutures. this leads to a higher rate of both exposure to suture techniques and suture execution. introduction: measuring performance in the operating room (or) is challenging. performance is a multifaceted construct a complex interaction of many behaviors and actions that reflect an individual's knowledge and skill. no assessment tool to date provides an expertise-based, comprehensive evaluation of the various aptitudes necessary to excel in the or, especially with respect to advanced cognitive skills. using qualitative methodologies, we previously defined behavioral themes that guide surgeons' behaviors, decisions, and actions, within a universal framework of domains that reflect intra-operative performance. the purpose of this pilot study was to use this framework to derive a comprehensive assessment tool and to obtain evidence for its validity as a measure of intra-operative performance. methods: an assessment tool was developed by a panel of surgeons and surgical trainees based on the five-domain model of intra-operative performance: ) psychomotor skills; ) declarative knowledge; ) interpersonal skills (two items); ) personal resourcefulness, and ) advanced cognitive skills (ten items). all items were rated on an ordinal scale of (inadequate) to (expert) and equally weighted. surgical residents and surgeons from a single academic center were evaluated on their performance during standard general surgery operations, for example, open inguinal hernia repair and laparoscopic cholecystectomy. for residents, there were evaluators -the attending surgeon and an observing surgeon. attending surgeons evaluated their own performances and were also assessed by observing surgeons. internal consistency, inter-rater reliability, and correlation of total scores with training level (junior residents, senior residents, staff surgeons) were calculated. likert scale questionnaires were administered to evaluate the tool's usability, feasibility, and educational value. results: fifteen subjects ( junior residents, senior residents, surgeons) participated. the total score on the assessment demonstrated significant differences between training levels ( figure) . inter-rater reliability was high (interclass correlation coefficient= . ), as were internal consistency between each domain score (cronbach's alpha= . ), internal consistency amongst items in the advanced cognitive skill domain (cronbach's alpha= . ), and internal consistency amongst items in the interpersonal skills domain (cronbach's alpha= . ). all assessments required less than five minutes to complete. overall, evaluators agreed that the assessment tool was easy to use, was comprehensive, and should be used routinely throughout training to track performance and provide formative feedback. conclusion: in this pilot study, we developed a comprehensive assessment tool for intra-operative performance and provide preliminary validity evidence for the score. surg endosc ( ) introduction: the purpose of this study was to evaluate the validity of our developed system for assessing suturing skills in laparoscopic surgery (fig. ) . we have updated numbers of participants and a comparison method compared with the last year report. methods and procedures: fig. shows our developed computerized system for objective assessment of suturing skills by using a laparoscopic intestinal suturing model, e-lap. the system includes a new artificial intestinal model that mimics living tissue and pressure-measuring and image-processing devices. each examinee performs a specific skill using the artificial model, which is linked to a suture simulator instruction evaluation unit. the model uses internal air pressure measurements and image processing to evaluate suturing skills. five criteria, scored on a five-grade scale, were used to evaluate participants' skills ( fig. ) . the volume of air pressure leak was determined by the volume of air inside the sutured artificial intestine. for example, for the criterion "air pressure leakage", the approximate midpoint of the acceptable range was grade . values lower than the minimum acceptable value received lower grades and those above the midpoint of the acceptable range higher grades. we enrolled surgeons who participated a simulator competition event at the th annual meeting of the japan society for endoscopic surgery (jses houston methodist hosptial, baylor college of medicine introduction: the sages flexible endoscopy course for minimally-invasive surgery (mis) fellows has been shown to improve confidence and skills in performing gi endoscopy. this study evaluated the long-term retention of these confidence levels and investigated how fellows have changed practices within their fellowships as a result of the course. methods: participating mis fellows completed surveys six months after the course. respondents rated their confidence to independently perform sixteen endoscopic procedures ( =not at all; =very). while the pre-and post-course surveys identified anticipated endoscopy uses and barriers to use, the -month follow-up survey evaluated actual usage and barriers to use in each fellow's practice. respondents also noted participation in additional skills courses and status of fundamentals of endoscopic surgery (fes) certification. comparison of responses from the immediate postcourse survey to the -month follow-up survey were examined. mcnemar and paired t-tests were used for analyses. results: twenty-three of ( %) course participants returned the -month survey. % had passed the fes skills examination and % had attended another flexible endoscopy course. no major barriers to endoscopy use were identified. in fact, fellows reported less competition with gi providers as a barrier to practice compared to their original post-course expectations ( % versus %, p. ). in addition, confidence was maintained in performing the majority of the endoscopic procedures, although fellows reported significant decreases in confidence in independently performing snare polypectomy (− %; p. ), control of variceal bleeding (− %; p. ), colonic stenting (− %; p. ), barrx (− %; p. ), and tif (− %; p. ). fewer fellows used the gi suite to manage surgical problems than was anticipated post course ( % versus %, p. ). fellows without fes certification reported loss in confidence to independently perform barrx (− %; p. ) and colonic stenting (− %; p. ), and also a % decrease in the use of gi suite to manage surgical problems (p. ) fellows who passed fes noted no significant loss of independence, changes in use, or barriers to use. % of fellows made additional partnerships with industry after the course. % stated flexible endoscopy has influenced their post-fellowship job choice. % would recommend the course to other fellows. the sages flexible endoscopy course for mis fellows results in long-term practice changes with participating fellows maintaining confidence to perform the majority of taught endoscopic procedures six months later, and over % reporting that flexible endoscopy influenced their career choice. additionally, fellows experienced no major barriers to implementing endoscopy into practice. the materials and methods: at our center, we formulated a laparoscopic mentorship program where a senior consultant was paired with a particular trainee resident for a period of weeks. consultants & residents were a part of the study. the or schedules were rearranged to accommodate these pairs. an evaluation of the residents' views was performed prior to the study and once at its completion, using a simple questionnaire with each parameter scored between & . results and discussion: continuous, consistent evaluation by a consultant over an extended period of time allowed them to assess their assigned resident's laparoscopic skill set. all pairs observed an increased frequency of errors being noticed & improved upon. the consultants stressed upon shedding undesirable operative habits. there was a significant improvement in residents' scores at the end of the short study. conclusion: we found that the short-term mentorship program was easy to incorporate within our or schedule and was well received by the participants. continuous short rotations under senior consultants appear to allow residents to not only fully observe and imbibe correct operative techniques, but also helps shed unfavorable habits. we are currently amid the second cycle of our study & looking forward to the results at the end of this academic year. introduction: colorectal cancer is one of the most common cancers in the united states. endoscopic submucosal dissection (esd) is an emerging minimally invasive technique that allows complete en-bloc resection and a much lower recurrence rate at long-term follow-ups. however, performing colorectal esd is technically demanding since the colorectal wall is thin and constantly moving, and potentially higher rates of complications (e.g., bleeding and perforations). hence, an adequate training for colorectal esd is needed to acquire basic proficiency with minimum complications. objectives: a virtual reality (vr)-based simulator with visual and haptic feedback for training in colorectal esd is being developed, which the aim to allow trainees to attain competence in a controlled environment with no risk to patients. in this work, a newly developed application of the virtual simulator that promotes the endoscopists to perform and assess technical skills in esd is developed. training tasks are built based on physics-based computational models of human anatomy with tumors. methods: the main modules of the vr-based simulator for colorectal esd involve: ( ) rendering; ( ) haptic interface; ( ) physics-based simulation; and ( ) performance recording and assessment metrics. the rendering engine allows surgical tasks to be performed in the three-dimensional virtual environment. haptic feedback mechanisms allow users to physically feel the interaction forces. physics-based simulation technologies are employed to enable the complicated simulation for performing virtual surgical tool-tissue interactions. the simulator can also collect learners' performance data to offer feedback based on the built-in metrics. results: four training tasks involving marking, injection solution, circumferential cutting, and submucosal dissection are designed to practice skills with different surgical tools. the marking task aims to identify the lesion. the injection solution task minimizes the risk of bleeding and perforation to protect the muscularis. in the circumferential cutting task, the objective is initial incision of the lesion with the surgical tools. the objective of the dissection task is to remove the tumor from the connective tissue of the submucosa under the lesion. conclusions: the vr-based simulator enables realistic esd tasks to provide a possibility for developing, validating and objectively evaluating the performance metrics in colorectal esd training, and offers an opportunity to rise up the learning curve before application to patients. background: the virtual translumenal endoscopic surgery trainer (vtest) simulator is a virtual reality system that was designed to train the hybrid-notes technique. transfer of skill acquired while training on the vtest was measured in a near-real cholecystectomy procedure staged in the easie-r model. methods: sixteen medical students were divided randomly and evenly into groups: control, training. all subjects performed the cholecystectomy procedure on the vtest simulator to establish a baseline (pre-test). the training group received training sessions, over a period of consecutive weeks, consisting of trials per session or as many trials as can be accomplished in one hour, whichever was achieved first. at the end of the training period, all subjects performed one trial on the vtest simulator (post-test), and again to weeks later (retention test). two months after that, subjects performed the hybrid-notes cholecystectomy procedure on an easie-r model. performance with the easie-r simulator was video-recorded, and three tasks within the cholecystectomy procedure were isolated for evaluation: clipping, cutting, and dissecting the gallbladder. objective performance measures, such as time and error, were extracted from the videos by two independent reviewers, while subjective performance was scored by four expert surgeons who were blinded to the training conditions. expert reviewers used a modified version of the operative performance rating system by the american board of surgery and the objective structured assessment of technical skills (osats) tool. results: there was no difference in task completion time between the control and training groups, (t( )= . , p =. ) in the cutting and clipping tasks. however, there was a significant difference in the number of errors, t( )=- . , p=. . there was no difference in subjective performance between the training groups for the clipping and cutting tasks. in the gallbladder dissection task, however, there was a statistical significance in "instrument handling" based on one of the surgeons' ratings (t( )= . , p=. ), and a statistical significance in "time and motion" based on another surgeon's rating (t( )= . , p=. ). conclusions: results indicate that weeks of training on the vtest simulator did not allow the subjects to transfer their learned skills equally to the near-real environment, even though they retained the skills when tested for retention. this new insight suggests that modification of the training method for different types of surgical skills may be warranted to optimize their transfer to the real environment. examining conclusions: this study provides evidence to suggest that for bariatric surgeons, experience and skills acquired in performing non-bariatric surgery may not translate to improved outcomes in bariatric surgery. as seen in this study, improvement in bariatric surgical outcomes is likely more dependent on experience specifically performing bariatric procedures. as there may be no benefit acquired from performing surrogate procedures, this may have implications in the design of subspecialty training programs and for accreditation purposes. . a universally adjustable cellphone holder was used where smartphones could be placed inside the fls box in order to capture the task from a similar angle as the onboard camera. residents were able to use their own smartphones to record their performance on each of the five fls tasks in high definition (hd) quality. after each practicing session, they would upload their videos to a designated folder on a password-protected computer in the simulation lab. this folder was linked to a cloud-based storage system that fls instructor had exclusive access. the faculty was able to review each video in the next hours and provide immediate feedback to the residents via email, over the phone or in-person. the video library of performance also allowed the instructor to track the progress of the residents and whether they reached proficiency level in all five tasks to take the fls examination. this program was offered to all surgical trainees. results: utilization of simulation lab to practice fls tasks increased significantly across all postgraduate years after implementation of this model. six residents took the fls examination. the passing rate of the residents remained the same ( % before and after) but their scores in fls manual skills improved significantly compared to the group prior to implementation. the residents evaluated this change positively and reported that the use of videos and immediate feedback by faculty was a valuable intervention in their learning experience. conclusions: the smartphone cameras are readily available and can be used for telementoring. incorporation of telementoring in standard proficiency based fls training can promote self-directed learning and improve the access to experts for immediate feedback as a crucial element of effective training in acquisition of laparoscopic skills. background: it is important that making individual procedures a language, and an objective qualitative evaluation for the laproscopic training. recently, task training and the sham operation using the virtual simulator are carried out for medical students as the basic laparoscopic maneuver training, but there are few reports of objective qualitative evaluation for the training. in this study, we investigated rubric evaluation as the qualitative evaluation for laparoscopic training. materials and methods: one hundred and six students in th grade of tokushima univ. were participated. basic laparoscopic task training (gummy band ligation, beads transfer, delivery of beads, gauze excision) with training box and sham laparoscopic cholecystectomy with virtual simulator were performed. task execution time and rubric evaluation which includes the evaluation standard that became a language for each maneuver were performed before and after basic task training and sham operation. the group who are bad at laparoscopic maneuver was decided by time exceeded in tasks more than two from before practice. relationship between the group who are bad at laparoscopic maneuver and the group which self-evaluation was higher in a rubric evaluation was investigated. results: in basic task training, average task execution time in all students was shortened after practice compared with before practice, but investigated individual, students exceeded in more than two tasks. rubric evaluation in basic task training showed no difference between self-evaluation and evaluation by tutor before and after practice. in sham laparoscopic cholecystectomy, all students and tutor showed high score by rubric evaluation after practice compared with before practice. some students showed higher score than tutor, especially in part of extension of operation field by elevation of the gall bladder, exposure of triangle of calot, and exposure of cystic duct. students who showed high score by self-evaluation in many maneuver of sham laparoscopic cholecystectomy also exceeded in more than two basic tasks. conclusions: as rubric evaluation showed the point of the maneuver is made a language definitely, it was useful for an objective qualitative evaluation for laparoscopic training. pre introduction: bariatric surgery candidates have the opportunity to research bariatric surgeons and hospitals prior to scheduling their elective surgery. pre-operative information sessions are important tools for bariatric surgeons to provide patient education while increasing their patient population. online education is becoming increasingly popular, but its utility over in-person education is uncertain. our objective was to compare patients attending the two most commonly used educational formats: online (webinars) and in-person (seminars) and determine which were more likely to undergo bariatric surgery. methods: we conducted a retrospective cohort study of , patients who attended pre-operative information sessions from january to december by reviewing data maintained by the obesity, prevention, policy and management (oppm) database from our institution. the patients were divided into two groups: those who attended an in-person session (n= ) and those who attended an online session (n= , ). the proportion of patients who went on to have bariatric surgery was compared between the two groups. to categorize the study sample, patient demographics, surgeon providing the information session, and procedure performed were compared between groups. multivariate logistic regression model was applied to compare the effectiveness of in-person session and online session. results: of , patients analyzed, % attended online information sessions ( % female, mean age ). the remaining % attended in-person information sessions ( % female, mean age ). analysis found that . % of patients who attended online information sessions went on to have a bariatric surgical procedure, while . % of patients who attended in-person sessions went on to have a bariatric surgical procedure. after controlling for differences in age and gender, results of multivariate logistic regression analysis indicate that patients who attended inperson sessions were % more likely to have a bariatric surgical procedure than patients who attended an online session ( introduction: knot security is the ability of knots to resist slippage as force is applied, and the optimal number of throws to ensure a secure knot improves efficiency and outcome. the literature on the accepted number of throws per type of suture material has been largely anecdotal, often referring to throws for silk, for polyglactin (vicryl), five for polydioxanone (pds), and six for polyproprolene (prolene). we report a pilot knot-tying study of four suture types to determine optimal numbers of throws. materials and methods: four senior general surgery residents (pgy- and above) and four attending surgeons participated. participants viewed a standardized instructional video and a one-handed knot-tying tutorial. they were instructed to tie one-handed knots, beginning each knot with two throws in the same direction, and square the third and subsequent throws in the opposite direction. each surgeon tied knots, using differenttypes of - suture material: silk, polyglactin, polydioxanone, and polyproprolene. suture types were evaluated using , , , or throws. the participants were randomized to both suture type and order of throw numbers. the knots were then tested on the f.a.s. t knot tester (sawbones, vashon island, wa) for slippage (insecure knot) or breakage (secure knot). generalized estimating equation (gee) analysis was used to determine optimal throw number. results: knots were individually tested on the knot tester for slippage and recorded as % slipped (see table) . the percentage of slipped knots varied by participant and ranged from to %. generalized estimating equation analysis suggested that the only significant variable when determining knot security was number of throws (p= . ), not suture type or participant training level. the optimal number of throws for - silk, polydioxanone, and polypropylene was five, whereas six throws was optimal for polyglactin. conclusion: knot security is dependent on the number of throws placed, and these optimal numbers were higher in our study than the commonly accepted number of throws. evaluation of take introduction: laparoscopic skills can be learned using portable simulators and these skills are transferrable to the operating room. several training regions within the uk have therefore developed and delivered home-based laparoscopic training programmes for junior surgical trainees. although performance improved in some, overall engagement has been poor. similar results have been observed in north america. the aim of our study was to uncover the reasons for poor engagement with home-based simulation with a view to developing a future, more successful, programme. methods: this was a qualitative study utilising focus groups. interviews were undertaken with key stakeholders involved in various laparoscopic home-based simulation programmes through the uk. training equipment comprised the eosim portable simulator paired with online training tasks. the tasks were similar to those used in the fundamentals of laparoscopic surgery programme (fls). basic metric feedback was provided (eg time to complete task). a total of individuals were interviewed, including surgical trainees, consultant trainers, training directors and programme faculty. this generated approximately hours of data which was coded using nvivo software. a basic thematic analysis was performed. results: trainees cited multiple competing professional commitments as a barrier to engaging with home-based simulation. they tended to focus on scoring 'points' which contributed toward career progression rather than tasks which were interesting, or associated with personal development. this approach is perpetuated by the surgical training system, which rewards trainees with points for publications and exams, but not for operative skill. this leads to conflict between trainers and trainees, the former expecting trainees to instead focus upon developing their technical abilities. trainees were unsatisfied with metric feedback and wanted individual feedback from consultant trainers (attending equivalent). trainees generally perceived consultants as lacking interest toward the programmes and training in general. however, some consultants were in fact unaware of the programmes being delivered and others felt lacking in confidence to deliver necessary training to trainees. conclusions: our findings are widely generalizable and have implications for any institution delivering a similar programme. as a means of improving engagement, the the inception of scheduled simulation study days, providing trainees with the opportunity for personalised feedback from consultants, has been suggested. equipping trainers with the necessary competencies to deliver training can be achieved by ensuring attendance at the necessary professional development courses. tackling the 'box ticking' culture is more challenging and may involve a move toward restructuring the current surgical training scheme. introduction: to provide evidence for the face and content validity of a hybrid active-shooter team training simulation and the impact of a hybrid curricular model on learner's engagement and performance. the following study was conducted because hospitals are increasingly threatened by active-shooter incidents, and no active and noticeable training is currently available to train hospital staff members. methods: thirty-five volunteers (medical students, residents and other allied health providers) from the university of minnesota affiliated medical centers were randomly selected and divided into control and experimental groups. the control group (n= ) was given a traditional lecture-style presentation. the experimental group (n= ) participated in the hybrid curriculum which included augmented reality, kinesthetic simulation, and debriefing components. following both curriculum styles, nasa task load index (tlx) surveys were completed by each group member. a final active shooter simulation experience was presented and evaluated by active-shooter trained raters using a checklist of critical actions from the department of defense. a post-simulation nasa tlx survey and post-test were provided. to assess face and content validation of a hybrid team-training simulation exercise to prepare healthcare personnel in the event of a hospital-related active-shooter crisis, a -point likert-scale survey determined the realism, utility, and applicability of this type of training while engagement and performance during the simulation were measured using a nasa-tlx survey and contrasted with the rater's evaluation. our study provided evidence to support the face and content validation of an active-shooter simulation team training curriculum as a useful adjunct to health care institutional safety planning. we demonstrated that this type of training requires an optimal level of cognitive activation to increases learner's engagement and performance. we concluded that the hybrid design of our curriculum was successful in delivering these optimal levels of cognitive stimuli by producing engaging team training simulation experience capable of motivating our learners to acquire the tactical skills and life-preserving behaviors consistent with better survival opportunities during a hospital related active-shooter crisis. the introduction: the virtual electrosurgical skill trainer (vest) provides surgeons and trainees with a hands-on approach to learning the best practices in electrosurgery. it is comprised of five modules covering tissue effects, stray currents, bipolar tools, monopolar tools and or fire safety. the module in this study teaches the origins of stray currents and shows the learner how they can cause damage to non-target tissues via direct and capacitive coupling. the aim of this study was to assess learning using the vest system. methods: the irb approved study followed a single group pretest-posttest design and was conducted at the sages learning center. thirty-eight subjects participated and out of these, % were attending surgeons while the rest were medical students, residents and fellows. % of subjects had prior fuse exposure, while the remaining had none. subjects were asked to complete a five-question multiple choice questionnaire before and after using the simulator. it assessed their knowledge in topics such as direct coupling, capacitive coupling and insulation failure. participants then used the simulator to complete three tasks. first, the subject used direct coupling to seal a vessel and observed the desired effects and potential pitfalls. in the second task the subject was immersed inside the peritoneal cavity and was directed to use the active electrode to observe how the activation of energy can cause capacitive coupling. in the third task the subject practiced evaluating the insulation of electrosurgical tools for defects. wilcoxon's signed rank test was used to differentiate between pre-and post-test scores, and the mann-whitney u test was used to differentiate between the groups of subjects as a function of fuse experience. results: the median score on the pre-simulator assessment was % and the post-simulator median score was % (p = . ). there was no statistically significant difference in pre-assessment scores between attending surgeons and the others (p= . ). subjects with prior fuse exposure scored significantly higher on the pre-module assessment compared to those that had no prior fuse exposure ( % vs %, p= . ). in the post-assessment their median scores were % and %, respectively (p= . ). conclusions: the vest simulator module successfully increased the overall participants' knowledge of coupling in electrosurgery regardless of level of surgical experience. participants with prior exposure to the fuse curriculum had increased knowledge on this topic at baseline as compared to participants without any fuse exposure. introduction: the objective of this study was to assess the reliability of a modified notechs rating scale for the evaluation of medical students' non-technical (nt) skills. the importance of physician nt skills for the safe care of patients is receiving increasing attention in the literature. tools to assess nt skills such as notechs that addresses communication, situation awareness, cooperation, leadership, and decision-making have been shown to be valid and reliable. despite its importance, the assessment of nt skills of medical students, our future physicians, has received little attention. methods and procedures: twenty-seven medical students participated in of acute care simulated scenarios, each approximately minutes long. video recordings of student performance were reviewed and assessed using a modified notechs rating tool adapted for these scenarios with input from a team of clinicians, nurses, and human factors specialists. the rating scale ranged from to , representing very problematic behavior (e.g., not vocalizing concerns or decision process) and representing model behavior (e.g., identifies future problems and remains calm to unexpected events). two reviewers rated all videos independently on the notechs domains and specific subscales. student scores in each nt skill domain and interrater reliability were assessed. results: a summary of the scores of each notechs domain is shown in table . the highest overall average score of a participant was . while the lowest was . . the intra-class correlation (icc; two-way random model) was . , and the cronbach's α coefficient was [ . . the lowest icc agreement was in the situation awareness domain ( . ) while the highest agreement was in leadership ( . ). conclusion: medical student nt skills during acute care simulated scenarios vary significantly using a modified notechs assessment. this newly developed tool provides a framework for educators to evaluate medical students' nt skills during simulation training. it further identified domains where students scored lower, such as situation awareness, and could be targeted for education. the moderate icc, between the . - . range, shows that further refinement of the tool is needed to reliably assess the constructs. future steps to obtain validity evidence include additional raters and applying the tool in non-simulated settings. introduction: a general misperception of the real concept of robotic surgery seems to be revealed in our clinical practice. despite its introduction almost years ago, robotic surgery is still related to many myths and beliefs. before designing a trial to see if these false awareness could impact on outcome, we measured this misperception by a survey. moreover we tested if medical school is able today to give to the future doctors a necessary knowledge about robotic surgery. with the same survey we explore the feelings about the introduction of the artificial intelligence in medicine and the perception of the consequences of a larger use of technology in medicine. methods and procedures: a multiple choice survey was designed and anonymously administered via the platform surveymonkey (http://www.surveymonkey.com). a total of questions were selected from the research team and included in the survey. the questionnaire was divided in three parts: the first was to get information on participants' population; the second asked specific questions about robotic surgery; the third focused on technology use in medical education. results: we received and analyzed questionnaires, of which totally filled. many undergraduates consider robotic surgery as "experimental", will prefer open surgery on themselves and see a risk for robotic surgery in damaging the patient-surgeon relationship. this situation is better for medical students, but still a great diffidence were encountered. % of ug consider robotic surgery as "experimental" vs only . % of ms (q ). most thought robotic surgery had been used for only years or less (q ). . % of ug and . % of ms gave the right answer (p=. ). almost % of ug see robotic surgery as a risk in damaging the patient-surgeon relationship. this is not seen among ms (q ) (p=. ). % of ug are fearful of robots used to operate them. this fear is significantly reduced among medical students (p=. ). ug were less familiar with the indications and uses for robotics. ms gave a correct response more frequently (q , . % vs . %, p= . ). conclusions: our results indicates that nowadays, the robotic surgery is related a lot of misperceptions and a generally low level of information. this general picture is partially mitigated during the medical school, but the level of knowledge is still low. a big effort seems mandatory in clarify every technical aspect and an ethic debate about robotics, technology and ai as part of medical curriculum is advisable. background: learning theory states that a certain level of physiological stress or cognitive activation is required to achieve optimal task engagement and performance by the learners. our study will seek to determine if a hybrid team training curriculum inclusive of a task-oriented interactive virtual environment could help achieve the optimal level of cognitive activation required to result in a higher task engagement and performance. methods: a total of thirty-five medical professionals from the university of minnesota participated in several team training simulations. participants were randomly selected to an experimental and control groups. the experimental group (n= ) was exposed to a hybrid team training module, consisting of a task-oriented augmented reality phase followed by a second and third phase consisting of a kinesthetic simulation scenario and debriefing, respectively. the augmented reality phase presented the trainees to an interactive -degree image of the same clinical room where the simulation would take place allowing for ''situated-learning'' to take place. during the learning phase, trainees were encouraged to interact and communicate with each other while completing the tasks allowing for ''social-learning'' to effect. the control group (n= ), educational component consisted of a traditional audiovisual lecture-style introductory presentation, a simulation, and debriefing. after completing their respective educational components, each group completed a nasa task load index survey to assess the cognitive load experience of the individual educational models. subjects were then exposed to a final simulation (test simulation) similar in content and structure to the initial simulation. this was followed by a second nasa tlx survey. raters evaluated both group level of engagement and performance using a validated checklist of critical actions. results: the experimental groups showed higher weighted overall nasa cognitive load index scores than the control group (p= . ) prior to the test simulation. the weighted nasa score remained elevated in the experimental participant groups following the test simulation, whereas in the control group the post-simulation nasa assessment revealed a decrease in cognitive load (p= . ). expert raters using a validated checklist determined that . ± . % of the experimental (hybrid curriculum) group and . ± . % of the control group appeared to be more engaged and performed better during the simulation. conclusions: pre-simulation task-oriented augmented reality learning environments designed to incorporate situated, and social learning virtual experiences can provide the optimal level of cognitive boost that can result in a higher participant engagement and performance during team training simulation scenarios. introduction: despite the huge importance of laparoscopy, medical students have a brief contact with this surgical specialty during medical school in brazil. usually, they get in touch with this specialty during the surgery clerkship in the last years of medical school. therefore, few students perform clinical research or develop interest for this area during graduation. objective: to awaken the interest in laparoscopy of medical students early in medical school, improving the development of clinical research projects, and to prepare new generations of minimally invasive surgeons. discussion: the academic league of videolaparoscopy was created in under the guidance of dr. gustavo carvalho from the university of pernambuco, brazil. an academic league is a group of medical students who are guided by a tutor to develop three areas: research, teaching, and clinical practice. every year new students join the league after being selected with a multiple question test and an analysis of the curriculum vitae. the students are stimulated to participate in laparoscopic procedures as observers, learning about the techniques and instruments. moreover, there are minimally invasive surgery lectures and courses during the year. general surgery residents can also be part of the program as tutors. they are encouraged to present lectures, and to assist with research projects. medical students participated of this program in years. % pursued a surgical specialty after graduation. % did minimally invasive surgery as a fellowship. conclusions: the students who participate in several activities provided by the league have an increased interest in pursuing the path to become a laparoscopic surgeon. background: surgical education is an active and adaptive process of developing knowledge, technical and non-technical skills. the rise of social media has created a paradigm shift in surgical education, with online learning platforms offering exposure to real-time content, expert instruction, and global collaboration. while these disruptive technologies evolve, their influence on surgical education has not been investigated. our goal was to evaluate the growth and impact of an online surgical education model-the advances in surgery (ais) channel. our hypothesis was that utilization and engagement with the platform continues to grow, providing novel methods of measuring successful education. methods: assessment of the platform's membership demographic, user activity, and engagement was performed from inception in to quarter . the ais channel uniquely provides free, high quality, innovative content from elite surgeons in scheduled and continuously available formats across colorectal, bariatric and endocrine surgery service lines. users login to access content, with demographics, time spent, and content accessed recorded as measures of active account utilization and engagement. the main outcome measures were overall membership trends, utilization patterns by region, content type, and surgical specialty for the platform. results: users were predominately male ( . %), surgeons ( . %), and ranged in age from to years ( . %). the main surgical subspecialty represented was colorectal ( . %). active account usage/weekly recurrence was . % ( % industry benchmark), with users engaged for a mean minutes/session (excluding live events). since inception, steady exponential growth was seen across several dimensions. registered users and unique ip addresses increased from over , and , in to over , and . million in , respectively. the number of countries represented increased to reach across continents. at present, over live surgeries and live congresses have been broadcast from countries, with over , surgical videos available on demand to facilitate surgical education. the greatest engagement is seen with live surgical broadcasts. conclusion: our analysis demonstrated proof of concept for a unique, online surgical education model to provide effective surgical education. success was validated through the increase in overall users, sustained active account usage, and global penetration. user preferences for live surgical broadcasts were seen. knowing the utilization and preference patterns, the platform can continue to evolve and enhance the learners' experience. with this growth and penetrance, there is the potential to globally improve patient outcomes and the quality of care provided. background: a realistic simulator for transabdominal preperitoneal (tapp) inguinal hernia repair would enhance the surgeons' training experience before they enter the operating theater. the purpose of this study was to evaluate the efficacy of d-printed tapp simulator in evaluating preoperative skill before entering operative theater. methods: surgeons in our institution were enrolled in this study. they performed simulation tapp and the performance score was measured using tapp check list. the tapp simulator allows for the performance of all procedures required in tapp. the correlation between post -graduate years (pgys), age, experienced a number of laparoscopic surgery (more than , less than ), experienced number of tapp and the performance score was evaluated. results: strong correlation between experienced member of tapp inguinal hernia repair and the performance score was evaluated in this study (r= . ). however, the correlation between pgy, age and score was weak ( introduction: as the field of laparoscopic surgery grows, the need for standard measures of complex laparoscopic surgical skills is apparent. fundamentals of laparoscopic skills (fls) testing is required to complete general surgery residency, but there is no standard metric to convey expertise in advanced laparoscopic procedures. in an effort to develop a standardized assessment of laparoscopic suturing expertise, a group of experts was surveyed using delphi methodology to reach consensus on observed laparoscopic suturing skills reflective of performing at an expert level. methods: expert laparoscopic surgeons participated in serial surveys via redcap (research electronic data capture). experts included surgeons who perform[ /year laparoscopic procedures that involve intra-corporeal suturing, obtained from the authors' personal and professions networks. using a point likert scale, participants were asked to agree/disagree if different observed laparoscopic suturing skills indicate performing at an expert level. these skills were chosen from prior assessment instruments in the literature and the authors' previously published work. tasks were considered to meet criteria for consensus and eliminated from the next round of the survey after reaching % consensus as "strongly agree." results of the previous round of surveys were shared with participants at the start of the next round. the predefined endpoint for the delphi was set as maximum of rounds, reaching % consensus on each skill, or if[ % of initial respondents fail to return for subsequent surveys. results: after the first round of the delphi survey, respondents met inclusion criteria. preliminary data demonstrated skills that reached consensus ([ % of respondents chose "strongly agree"): forehand suturing, avoiding tissue trauma, having a technically acceptable final product (ie. tight closure), and tying a secure knot at the end of suturing. items did not approach consensus (\ % of respondents chose "strongly agree" or "agree"): alternating hands for each throw while tying, never missing a target when grabbing needle/suture, alternating direction of throws when tying, and backhand suturing. data from all four rounds of surveys as well as the final draft of the assessment instrument will be available at time of presentation. conclusion: preliminary data of this delphi study allowed us to reach consensus amongst a group of expert laparoscopic surgeons on the characteristics of expert laparoscopic suturing, which will allow creation of a comprehensive assessment tool for this domain. validation of such a tool will help advance the surgical field towards true competency-based credentialing and promotion. the study was designed to assess the knowledge of scp among european surgeons (specialists and residents). additionally, surgeons' opinion on usefulness of each of the rules of scp was gathered. the data were analyzed in terms of differences between residents and specialists. this is to set ground for and an educational program and increase the safety of elective laparoscopic cholecystectomy by minimizing the occurrence of cbdi. methods: the data on the knowledge of scp and opinion on usefulness of its rules were gathered in form of an anonymous questionnaire distributed among participants of several surgical conferences in poland. the questionnaire then asked about the surgeon's experience in terms of cholecystectomies performed and the number of complications in form of cbdi. it then listed the scp rules and asked the surgeon about their opinion on usefulness of each of the rules on a -point scale. gathered data were subject to statistical analysis and a comparison between specialists and residents was performed. the study has been registered in the clinicaltrials.gov-nct . , although these numbers are still low. significant differences in the mean usefulness score between residents and specialists were observed in regard to two rules: rule was found more useful by residents (mean score , vs. , , p= . ), whereas rule was found more useful by specialists (mean . vs. . , p= . ). the awareness of the sages safe cholecystectomy program in poland is still low and needs to be promoted. both surgical residents and specialists consider the rules of scp to be useful during surgery, although there are slight differences in the usefulness scores between the groups. an educational program to promote and further implement the scp should be established. introduction: transanal total mesorectal excision (tatme) has attracted substantial interest amongst colorectal surgeons throughout the world. technical challenges of the technique however have been acknowledged by early adopters and this may underpin the early reports of visceral injuries which occurred during the perineal phase. evidence from previous surgical training programs suggest that a structured proctorship programme can shorten the learning curve, operative time and most importantly reduce major complications. the aim of this study was to report on the first national pilot training initiative which was developed in the uk to ensure safe introduction of this technique. methods: a pilot training programme for the uk has been established in partnership with the healthcare industry, and supported by the association of coloproctology of great britain and ireland. the programme consists of three phases: (i) development of a consensus process on the optimum training curriculum of tatme from all relevant stakeholders, including experts, early adopters, and potential learners, to guide the training of this technique (ii) piloting of this training curriculum and (iii) assessment and quality assurance mechanisms to monitor training and measure outcomes. results: a cohesive multi-modal training curriculum has been developed providing clear guidance on case selection, supporting multi-disciplinary and multimodal training including online modules, dry-lab, purse-string simulators, cadaveric training and formal clinical proctoring programme. the uk pilot programme opened for applications in may and, after a rigorous selection process, the initiative was launched in september with trainers mentoring consultant colorectal surgeons from five centres. the selection of learners was based on suitable case volume and prior experience in laparoscopic rectal surgery. objective assessment tools were applied to an unedited video of a laparoscopic rectal surgery case for each applicant. for the selected centres, access to the ilapp tatme app was provided to access educational content including operative video footage, prior to attending a bespoke cadaveric workshop. each learner will then benefit from a structured, centrally organised and funded proctorship programme at their own institutions. a global assessment score form has been specifically designed to monitor training and a formal accreditation process will be used to sign off each learner using competency assessment tool. data on the cadaveric workshop and initial outcomes of the clinical mentorship will be presented at the conference. conclusion: a competency-based pilot training programme for transanal total mesorectal excision has been launched in the uk to support safe introduction of this technique. practicing on a fls trainer box is effective but requires large amount of consumables and is scored subjectively. the purpose of this study is to evaluate the face validity of the intracorporeal suturing task on a virtual fundamentals of laparoscopic surgery simulator (virtual fls). we hypothesize that the virtual fls will demonstrate face validity. methods and procedures: after a video demonstration and a practice period, twenty-three medical students and residents completed an evaluation of the simulator. the participants were asked to perform the standard intracorporeal suturing task on each of the virtual fls and the traditional fls box trainer. the presentation order of the devices was balanced. the performance scores on each device were calculated based on time (seconds), deviations to the black dots (mm), and incision gap (mm). the participants were then asked to finish a -question questionnaire regarding the face validity of the simulator. participants answered questions with ratings from (not realistic/useful) to (very realistic/ useful). a wilcoxon signed ranks test was performed to identify differences in performance on the virtual fls compared to the traditional fls box trainer. results: responses to of the questions ( . %) averaged above a . out of . those questions that rated the highest were the degree of realism of the target objects in the virtual fls compared to the fls ( . ) presently, most training methods for thoracoscopic esophagectomy use live porcines; this presents several problems including cost, long preparation times, and ethical issues. these problems further prevent frequent training. currently, no alternative models for thoracocopic esophagectomy training. we report, for the first time, the development and use of a non-biomaterial training model for thoracoscopic esophagectomy. methods: we collaborated with sunarrow co., ltd. (tokyo, japan) to develop the training model. we created organ models for esophagus, trachea, bronchus, aorta, vagus nerve, recurrent nerve, bronchial artery, lymph node, vertebrae, azygos vein, and thoracic duct, and filled the models with a polyvinyl alcohol hydrogel. the gaps between organs were filled with a filler material mimicking connective tissue. we chose a synthetic resin that closely mimics the characteristics (rigidity or elasticity) of each organ. after each organ was fixed, the model was covered with a filler to create a pleural membrane to allow training in peeling operations. in addition, because a patient plate was attached to the rear of the training model, excision with an energy device was possible and more closely simulated surgical conditions. results: using the training model resulted in a highly satisfactory level of experience in three trainees. the trainees were able to learn anatomical positions and sequence of surgical procedures, including endoscope handling. centre for rural health, aberdeen university introduction: as doctors become expert in a complex procedure, they develop automatic nuances of performance that are difficult to explain to a peer or a trainee (so called 'unconscious competence'). traditional methods which aim to allow sharing of expertise have limitations: concurrent reporting alters the flow of the task at hand while retrospective reporting is subject to bias and often incomplete. iview expert is a technique validated in the aerospace domain which externalises an expert's cognitive processes, without disrupting the task at hand. the aim of this project is to assess the feasibility of adapting the technique to medical training. methods: this was an observational case study in which an expert endoscopist wore a head mounted camera to capture a complex procedure (colonoscopy). captured video was reviewed during a facilitated debrief which externalised the expert's cognitive processes. the debrief was recorded and formed an audio commentary. the video and accompanying audio commentary formed a learning package which was watched by a specialty trainee. the technique differs from standard procedural videos in that it provides a more detailed insight into cognitive processes of the expert. this is achieved through the debrief, which encourages reflection upon kinaesthetic (head movement) as well as auditory and visual cues, resulting in a higher level of experiential immersion. questionnaires examined acceptability and educational value of the technique using likert scales and free text answers. quantitative data were presented using basic descriptions in terms of agreement with statements. qualitative data from free text responses were coded in order to identify key themes. results: the expert agreed that wearing the camera was acceptable and did not interfere with the procedure, nor usual decision making processes. qualitative analysis revealed the debrief process to be associated with a high level of experiential immersion: "as if they were there". both the expert and the trainee strongly agreed that the process was educationally valuable and that they learned something new. qualitative analysis demonstrated that the technique revealed useful and unique nuances of the procedure. the intervention could represent a powerful adjunct to existing training methods, especially amongst more experienced practitioners. we are currently undertaking a larger study involving a greater range of procedures with more learners. introduction: endoscopy is an important skill for general surgeons to possess. however, there is lack of training within surgery residency programs. we implemented a one-day endoscopic surgery course with the aim of improving the confidence of surgical residents in performing endoscopic procedures. we also aimed to examine the effect of the exposure to this course on self-reported confidence in performing endoscopic procedures. methods and procedures: the fundamental of endoscopic surgery course at texas tech university health science center is a one-day course consisting of both didactic training and lab training. the didactic part of the course is taught by attending physicians and focuses on the basics of endoscopy, management of upper and lower gastrointestinal (gi) bleed, and techniques to perform a variety of gi endoscopic procedures on swine esophagus and stomach explant. the lab portion of the course allows residents to perform different endoscopic surgical procedures with the attending physicians providing guidance. residents from pgy- to pgy- participated in the course. a -item questionnaire that measured the self-reported confidence in performing several endoscopic procedures on a - likert scale was administered before and after the course. results: twenty-two participants successfully completed the training and the questionnaires. a significant improvement was observed in the overall confidence in performing a variety of endoscopic procedures ( . ± . , p. ). the improvements remained significant even after controlling for the years of postgraduate surgical training (p. ). conclusion: the one-day fundamental of endoscopic surgery course enabled residents to be more confident with endoscopic procedures. overall, the residents felt that the course was helpful and would like to attend more than one session per year. this course should be held, at least, annually to allow the general surgery residents to become even more confident with this important skill. by being more confident in their surgical endoscopy skills, they will ultimately be able to provide better care for patients. introduction: a course evaluation study on the effectiveness of improving laparoscopic skills of surgical residents using swine models was evaluated through a self-report questionnaire administered before and after course completion. the purpose of the training is to provide surgical residents opportunities to practice and advance their laparoscopic proficiencies. methods and procedures: participating residents in all post-graduate year levels (pgy through pgy , n= ) were provided anesthetized pigs with which to perform a variety of simple to complex laparoscopic cases. prior to training, residents were given a questionnaire composed of eleven questions requiring the subjects to rate their confidence in performing various laparoscopic procedures on a - likert scale. after completion of the course, an identical questionnaire was distributed with two additional questions relating to the overall impact of the course. all statistical analyses were conducted using r statistical software (version . conclusion: overall, one-day hands-on training using swine models improved resident's skills, confidence, and understanding of laparoscopic surgery. the information acquired through the questionnaire emphasized the importance of providing a laparoscopic training course as a standard requirement at all medical institutions. allowing opportunities for surgical residents to practice their laparoscopic skillset will not only help in their individual academic advancements, it will allow them to provide optimum care for their patients. background: learning laparoscopy is difficult and many educational tools including simulation training are required. feedback plays a crucial role for motor skill training but require expert tutors and its time consuming. e-learning increases knowledge acquisition through a more interacting multimedia experience and reduces de costs of learning. in the last decade multiple applications (apps) have been developed for mobile medical training. a new ios app was developed using specially designed educational videos that explain the main technical aspects in advanced laparoscopy through simulation training. the aim of this study is to present the first results of its incorporation in a surgical simulation lab as a complement of effective feedback. methods: twenty-five consecutive residents were trained in our simulation lab through a session validated training program for the acquisition of advanced laparoscopic skills needed for the performance of a laparoscopic hand-sewn jejuno-jejunostomy. every session had written instructions and a basic tutorial video. the app consist two main sections, the first one explains the essential techniques needed for intracorporeal suturing and the second is a complete walkthrough of the validated training program. the trainees were divided in two groups, the first was trained without using the app (napp) and the second group was trained using the app (yapp). both groups of trainees could ask for feedback anytime they needed. trainees were assessed before and after the training program using validated rating scales and the number of necessary tutor-feedback sessions were registered. finally the yapp group answered a survey about the strengths and weaknesses of the app for learning advanced laparoscopic skills. results: twenty-five residents completed the training program; yapp and napp. both groups finalized their training with no statistical significant differences in their scores (p: . ). the number of tutor-feedback needed to complete the training in the yapp vs napp was of [ ( - ) vs ( - ) (p. )] respectively. in the questionnaire all participants considered that the app was effective for learning advanced laparoscopy. over downloads have been registered since the app was published in the apple app store in . we present a novel smartphone app that guides laparoscopic training using simulation-based educational videos with very good results. the use of app guided learning reduces de need of expert tutor feedback reducing the costs of simulated training. jemin choi, young-il choi; kosin university gospel hospital purpose: laparoscopic appendectomy (la) has been widely performed for acute appendicitis. in addition, minimally invasive surgery such as la is common surgical technique to the surgical residents. however, single incision laparoscopic surgery (sils) is a challenge to inexperienced surgical residents. we described our initial experience in teaching sils procedure for appendectomy in our medical center. methods: twenty nine cases of single incision laparoscopic appendectomy (sila) were performed by single surgical resident and cases of la were performed by surgical residents and boardcertified surgeons. a study was reviewed retrospectively. ( ) clinical stressors (i.e., vitals of patient coding). we developed a stress simulator testbed by integrating an fls box trainer with a linux computer, running custom c++ code. the code generated various stressor conditions, while recording sensor data from the trainer and human operator. we tested groups of participants in an irb approved trial including: novices (non-medical students), intermediates (medical students), and experts (pgy residents and fellows). the study consisted of subjects performing the peg transfer and the pattern cut six times (baseline, four randomized stressors, posttest). after each task, the nasa-tlx survey was administered to determine the overall workload of that stressor condition. an analysis of variance was conducted to identify significant trends in terms of stressor type. results: when compared to baseline nasa-tlx scores, the intermediate group had the greatest changes in overall workload than novices and experts (p= . ). additionally, the change between baseline and post-test workload was significantly lower than for the environmental, negative evaluative, and clinical stressors (p= . ). for pattern cutting, subjects reported a significantly lower perception of failure (p= . ) in both the positive evaluative (mean= . ) and post-test conditions (mean= . ), yet, though not statistically significant (p= . ), the measured accuracy in the task during the positive evaluative condition was actually worse ( . %), second only to the pre-test accuracy ( . %). the best accuracy for pattern cutting across all expertise levels was % for the post-test followed by . % in the negative evaluative condition. these results are interesting as they show that despite perceived improvements in performance with a positive feedback condition, performance actually degrades and is better in the negative feedback condition, which is perceived to be more difficult. these results were not found in the peg transfer task, which is arguably an easier task. conclusion: from the evidence gathered in the study, it is clear that there is a correlation between distractors and performance. further analysis is needed to identify the relationship between the type of stressor, and inherent difficulty of the tasks, in terms of which type of stressor best improves learning and outcomes. surg endosc ( ) each received credentials to perform diagnostic and therapeutic ercp from their respective hospitals in nevada, minnesota, and idaho. one continues to teach ercp to general surgery residents, and another taught the skill to fellows in an advanced endoscopy fellowship. all three continue to use ercp in their practice ( to times per month), as they each specialized in a field that utilizes ercp routinely. choledocholothiaisis is the most frequent indication, though ercp is also performed for iatrogenic biliary duct leaks, traumatic biliary or pancreatic duct leaks, chronic pancreatitis, and malignancy. conclusions: training in esophagogastroduodenoscopy and colonoscopy is required for general surgery residents, but the addition of ercp to select residents' training enables them to completely manage their patients' surgical disease. the training of select general surgery residents in this skill has been successful, evidenced by the continued use of ercp in the practices of three residents who completed this training program at our institution. the decision to train residents in this skill should be left to individual program directors and department chairs. we recommend that residents selected for this additional training should plan to practice in specialties where ercp can be implemented. conclusion: same-day discharge after nissen fundoplication and hiatal hernia repair is feasible for select patients. one major challenge for same day discharge is the current insurance provisions required for hospital reimbursement. within the parameters of this study, bmi and asa score did not differ between discharged and admitted patients, while older age and increased procedure duration were associated with need for admission. premkumar anandan, ms, facs; bangalore medical college and research institute introduction: minimal access surgery is an imperative element of enhanced recovery program and has significantly improved the outcomes. enhanced recovery program (erp) synonym "fast track" surgery "was first conceived by dr henrich kelhet. largely described for colorectal surgery and reported to be feasible and useful for maintaining physiological function and smooth the progress of recovery. most of the patients who present for surgical emergency are not adequately prepared and many are not in normal physiological state. the feasibility of enhanced recovery programs protocol in such emergency minimal access surgery remains indistinct. this study was designed to validate an enhanced recovery program in patients who undergo emergency minimal access surgery. introduction: pathways for enhanced recovery after surgery (eras) have been shown to improve length of stay and postoperative complication rates across various surgical fields, however there is a relative lack of evidence-based studies in bariatric surgery. the objective of the current study was to determine if starting a bariatric full liquid diet on postoperative day (pod) zero was associated with shorter length of stay (los) for patients who underwent laparoscopic sleeve gastrectomy (lsg) or roux-en-y gastric bypass (rygb). methods: retrospective review of a prospectively collected dataset was conducted at a single institution before and after implementation of a new diet protocol for lsg and rygb. postoperative diet orders were changed from full liquid diet on pod to pod . length of stay and -day readmissions were reviewed from june to august . independent samples t-tests were used to compare continuous variables and chi-squared tests for categorical variables before and after diet change was implemented. patients were excluded if they were undergoing revision surgery, were discharged directly from pacu, or had significant intraoperative complications or required reoperation within the same admission. introduction: data suggests value in using tap (transversus abdominis plane) neural blockade in abdominal surgical procedures. we deploy tap blockade using liposomal bupivacaine via ultrasound (us) as part of a narcotic sparing pain management pathway for patients undergoing abdominal surgery in our rural community setting. our goal was to evaluate adequacy of postoperative discomfort and the success in avoiding narcotic usage. methods and procedures: records of patients undergoing abdominal surgical procedures performed by one surgeon over an month period were reviewed under irb approval. patients taking narcotics prior to the procedure (except for discomfort due to the condition being surgically treated) were excluded from analysis, as were those admitted to the hospital for postoperative treatment. us guided lateral tap blocks were performed by the surgeon using mg of liposomal bupivacaine and mg of bupivacaine in the or prior to the incision. unilateral block was performed for unilateral procedures (e.g. inguinal hernia) and bilateral for laparoscopic or midline procedures. incisional sites were treated with a field block of mg of bupivacaine. prescriptions for medications included , mg of acetaminophen qid and mg of naproxen sodium tid for days. a prescription for tramadol ( to mg prn up to times daily; tablets with no refill) was given. patients were seen in followup two weeks postoperatively. data (following standard scales/metrics) for patient-reported-outcomes e.g. pain, nausea-vomiting, & fatigue will be analyzed with the above data and the analysis with conclusions will be presented & discussed. federico sertic, md, ashwin gojanur, dr, ahmed hammad, md; guy's and st thomas' hospital introduction: the aim of this project is to assess the quality of post-operative pain relief in colorectal surgery and identify patients in whom pain management has not been effective, in order to improve the quality of post-operative care. effective management of post-operative pain has long been recognised as important in improving the post-operative experience, reducing complications and promoting early discharge from hospital. standards: all patients should be pain free at rest, % of elective patients should be told about what analgesia they will have post-operatively, % of patients should be satisfied with their pain management and % of patients should feel staff did everything they could to control their pain. methods and procedures: questionnaires were given to patients on the day prior to discharge. questions about pre-operative and post-operative pain experience were asked. data regarding post-operative analgesia were collected from medication charts and medical notes. data were collected over a period of two months (august/september ). range of procedures: elective laparoscopic abdomino-perineal-excision-of-rectum with igap flaps, elective laparoscopic right hemicholectomy, laparotomy+bowel resection/stoma formation ( elective, emergency), elective repair of parastomal hernia, appendicectomy ( laparoscopic elective, laparoscopic emergency, laparotomy emergency) and elective reversal of ileosomy. pain scores ( - ): immediately post-operative pain, day post-operative pain, post-operative pain after day and pain on moving/coughing/straining. results: mean immediate post-operative pain score was . ( % of patients with score +), mean day post-operative pain score was . , mean post-operative pain score after day was . , mean pain score on moving was . ( % of patients with score +), mean pain score on coughing/ straining was . ( % of patients with score +). % of patients were satisfied with their post-operative pain management and felt that the staff had done everything they could to manage their pain. % of patients were not aware of their post-operative analgesia regimen and % did not know how regularly they could request analgesia. conclusions: effective management of post-operative pain is a key part of post-operative care and an important component of enhanced recovery programmes. patient satisfaction with pain management has been found to correlate with received pre-operative information. increasing ward nurses' and acute pain teams' knowledge is important in improving patients' pain experiences. interestingly, those patients who had a background of long-term opioid requirements reported that they were satisfied with their pain management. methods and procedures: a patient undergoing a standard ultrasound guided ql block by an anesthesiologist established the baseline anticipated response, and procedure time. the procedure, performed under sedation preoperatively, required over minutes. for this study, patients undergoing laparoscopic colorectal surgery were administered a lateral ql block (modified ql ) under ultrasound guidance by the operating surgeon. ml of a mixture ( ml injectable liposomal bupivacaine suspension, ml . % bupivacaine hydrochloride and ml normal saline) was injected bilaterally, after induction, skin preparation, draping, and prior to the operation. postoperative narcotic use and pain vas scores were documented. results: six patients were administered a bi-lateral ql block intraoperatively. procedures were: laparoscopic sigmoid colectomies, one end ileostomy reversal, laparoscopic completion proctectomy with ileal pouch anal anastomosis, and a laparoscopic descending colectomy. of the narcotic naïve patients, mean pain vas on post op days , and were . , . and . respectively within a multimodality pain management/enhanced recovery program, where standing orders prompting narcotic administration by nursing staff is pain vas . all were discharged on pod or without narcotic prescriptions. two of the patients were chronic narcotic users, and they were discharged on their baseline narcotics, i.e. without additional narcotics. all intraoperative blocks were performed in less than minutes. conclusion: a novel, surgeon-administered lateral ql block under ultrasound guidance, is feasible and provides post-operative pain control. patients are discharged home on no/baseline narcotics. a randomized controlled trial is being constructed based on these striking findings. keywords: lc-laparoscopic cholecystectomy, ga-general anaesthesia, sa-spinal anaesthesia. nikhil gupta, rachan kathpal, dr, arun k gupta, dr, dipankar naskar, dr, c k durga, dr; pgimer dr rml hospital, delhi introduction: cholecystectomy have shown some advantages when done under spinal anaesthesia (sa) and associated with less intra operative and post -operative morbidity and mortality. laparoscopic cholecystectomy (lc) under regional anaesthesia alone included patients with coexisting pulmonary disease, who are deemed high risk for ga. the aim of the present study is to assess the efficacy and safety of laparoscopic cholecystectomy under sa. materials: this prospective, interventional study was conducted on patients with chronic calculous cholecystitis attending general surgery out-patient department of our institution. results: in our study, intraoperative complications recorded were hypotension, bradycardia, intra op shoulder tip pain, bleeding from the liver bed, bile spillage, post-op pain and vomiting. % patients had intraoperative pain, % had shoulder tip pain, . % had bradycardia, . % had hypotension, . % had bile spillage and . % had bleeding. laparoscopic cholecystectomy under spinal anaesthesia should be promoted more even in developing countries but we need to establish well evaluated safety guidelines that could be followed faithfully for minimizing the risk of complication. background: the "opioid crisis" has taken over headlines with increasing public attention brought to the drastically increasing rates of addiction to prescription narcotics. in , the american society of addiction medicine reported million americans with an addiction to prescription pain relievers and a four-fold increase in overdose related deaths. in a medical setting, increased opiate use is associated with increased rates of delirium, ileus, urinary retention, and respiratory depression. these risks are increased in the obese/bariatric population. transversus abdominis plane (tap) block is a safe and effective approach to achieve optimum pain control. it reduces the use of opiates in patients undergoing major abdominal surgery. however, there is currently no data in the literature examining its use in the bariatric population. our study examines the use of liposomal bupivacaine for tap block in patients undergoing laparoscopic sleeve gastrectomy (lsg). methods: sixteen patients undergoing lsg with tap block were compared with historical cohort of sixteen patients undergoing lsg without tap block (standard group). the primary outcome measured was post-operative in-hospital opiate use (morphine equivalents). statistical analysis was performed using student's t test for continuous variables and fisher's exact test for categorical variables. results: both groups were well matched in regards to bmi, age, and asa class. there was a significant decrease in the post-operative use of opiates with the use of the tap block ( . mg in the tap block group vs. mg in the standard group; p . ). there was no difference in the mean length of stay between the two groups. there was an increase in the mean operative time with use of the tap block ( minutes in the tap block group vs. minutes in the standard group; p. ) conclusions: the use liposomal bupivacaine for tap block provides substantial analgesia, allowing for significant reduction in post-operative opiate use in our bariatric patients. this can be an important adjunct in pain control for the bariatric population and aid in post-operative complication risk reduction. introduction: the objective of this study was to identify variation in weight and demographics in the distribution of pre-operative clinical characteristics between super obese females compared with males who were about to undergo bpd/ds surgery. as the american obesity epidemic increases, morbidly obese patients have become integral to every surgical practice; they are no longer limited to bariatric surgeons. every clinical insight helps the surgeon to optimize outcomes when operating on and managing these medically fragile individuals. in this context, however, clinically and statistically significant differences in demographics, body mass, and in the distribution of weight-related medical problems between super-obese women and men are unknown. introduction: a transversus abdominis plane (tap) block is an ultrasound-guided injection of local anesthetic in the plane between the internal oblique and transversus abdominis muscles to interrupt innervation to the abdominal skin, muscles, and parietal peritoneum. currently there are incongruent findings on the benefit of this regional anesthetic to surgical patients, particularly the obese population. we hypothesized the addition of a tap block in an enhanced recovery pathway (eras) for bariatric patients would decrease opioid use and shorten hospital length of stay. methods: a retrospective review of all patients who underwent bariatric surgery at a single institution from january to december was performed. patients were identified as: no tap block (no tap), tap blocks that were performed after induction either pre-surgery (pre-tap) or post-surgery (post-tap). the primary outcome was time to first opioid (min) and total morphine (mg) equivalents in pacu. objective: prolonged postoperative ileus increases hospital length of stay and therefore impacts healthcare costs. although many surgeons recommend ambulation in the postoperative period to hasten return of bowel function, little evidence exists to support this practice. our hypothesis is that early ambulation does reduce the time to return of bowel function after intestinal surgery. methods: a subset of patients undergoing intestinal surgery from an ongoing, prospective trial evaluating perioperative physical activity was analyzed. preoperatively, patients wore an activity tracker for a minimum of three days to establish a baseline activity level, measured by daily steps. postoperatively, steps were recorded for days. patients were included in this study if they underwent an operation on the small bowel, colon, or rectum. resolution of postoperative ileus was defined as the postoperative day when patients were noted to meet all of the following criteria on review of nursing documentation: passing flatus, stooling or having ostomy output, and tolerating a regular diet without intravenous fluids. "early" postoperative activity was defined as the average number of daily steps during the first two postoperative days. discussion: these results suggest the patients who received an intraoperative block laparoscopically were more likely to be able to spend less time in the post anesthesia care unit and be discharged home the same day. based on these results, additional process improvement ideas will be implemented in an attempt to improve outcomes. riley d stewart, md, msc, frcsc, james ellsmere, md, msc, frcsc; dalhousie university division of general surgery introduction: oropharyngeal and gastrointestinal (gi) perforations from bbq brush bristles are being reported in the literature with increasing frequency. media attention to this problem has increased awareness by the public. most commonly, bbq bristles lodged in the gi tract can be removed endoscopically or pass without complication. rarely, surgical intervention is required for removal of the bristle or drainage of an associated abscess. we report a case of gastric perforation by a bbq bristle leading to a pancreatic abscess. case report: a -year-old male presented to a regional center with epigastric pain and malaise. his medical history included: hypertension, dyslipidemia, gerd, and smoking. his surgical history included: a tonsillectomy, excision of bronchial cleft cyst, and an umbilical hernia repair. on presentation, his laboratory investigations where unremarkable aside from an elevated white blood cell count. investigations including an abdominal x-rays and an abdominal ultrasound were unremarkable. he was initially treated with a proton pump inhibitor for presumed peptic ulcer disease. he returned to the local emergency room, no better than before. a ct scan was arranged which demonstrated a foreign body at the pylorus consistent with a bbq bristle and a peripancreatic fluid collection (figs. & ) . a gastroscopy failed to identify the bristle. he was admitted, placed on iv antibiotics and referred to our center. despite several days of antibiotics prior to arrival, the collection size on repeat ct scan had increased and the patient had ongoing pain. we repeated the endoscopy with a side viewing endoscope. the perforation was identified posteriorly at the pylorus. the bristle had migrated into the peripancreatic space. the perforation was cannulated with a jagtome. fluoroscopy was used to confirm the position of a wire in the fluid collection (figs. & ) . pus was drained from the collection into the stomach by placement of a french pigtail catheter (fig. ) . the patient was discharged pain free the following day. the patient was asymptomatic at weeks' follow-up. a repeat ct scan showed resolution of the abscess and safe migration of the bristle and stent out of the gi tract (fig. ) conclusion: to our knowledge, this is the first reported transgastric endoscopic drainage of a peripancreatic abscess caused by a bbq bristle gastric perforation. this case is a demonstration of the ever-expanding role of therapeutic endoscopy in a surgical practice. andrew w white, md, carl westcott, md; wake forest baptist medical center introduction: endoscopic balloon dilation of the gastroesophageal junction (gej) is generally limited to mm in diameter. in many stenotic or spastic disorders of the gej mm is just not big enough. larger balloon sizes are available ( and mm), although these are deployed under fluoroscopy without endoscopy. thus, these larger dilations are often not feasible at the time of the diagnostic endoscopy because different facilities and/or equipment are needed. also, fluoroscopic mm balloon dilations are associated with a percent perforation rate. to address these shortcomings we present an experience with a retroflexed "against the scope" balloon dilation of the gej. in detail, the gej is visualized while retroflexed and a balloon is then placed through the scope. the gej is cannulated next to the scope and deployed. please see the attached image for example. methods and procedures: a retrospective chart review was performed for a single surgeon during the past five years. we identified those who had retrograde dilations and evaluated the indications, repeat dilations, complications and symptomatic response. results: a total of retrograde dilations were performed on patients with gej related dysphagia. the average age was . years. of dilations were with a mm balloon while other dilations used as small as a mm balloon. dilations were performed for persistent dysphagia after cardiomyotomy between and days after surgery. other indications for dilation were dysphagia after fundoplication ( / ), dysphagia after paraesophageal hernia repair ( / ) and achalasia during pregnancy ( / ). patients required a total of repeat retrograde dilations at an average time of days after previous dilation. there were instances reported where the dilation did not improve symptoms. there was mucosal breakdown noted in instances although there were no perforations. bleeding was noted in instances although this was always minimal and selfresolving. conclusions: retrograde endoscopic dilation is safe and effective in this small series. the mm balloon against a mm scope gives a mm diameter, but a different shape and a decreased total circumference. there is a possible added safety advantage given that the balloon is inflated under visualization. it can be inflated in steps or stopped if it appears too aggressive. in addition these larger dilations were provided at the time of the initial diagnostic egd without extra equipment. more studies are needed to compare retrograde endoscopic dilation to other methods of management of gej stenosis. introduction: robot-assisted surgery allows surgeons to perform many types of complex laparoscopic surgical procedures. more and more patients are treated with this sophisticated system. however, all the instruments used in the currently available surgical robot system is rigid. therefore, there exists a limitation in the extent of reach to the deeper surgical fields. in order to overcome this difficulty, we are developing a novel flexible endoscopic surgery system (fess) which has flexible single port platform of cm in diameter, independently controlled endoscope and instruments, open architecture that is compatible with existing flexible devices and a magnified d hd camera that has sensors of both rgb and infrared. furthermore, the system is smaller and would be more cost-effective than existing robotic surgical system. a preliminary experiment was performed in surgical procedures using porcine model to evaluate effectiveness and feasibility of fess. methods and procedures: experimental protocols were approved by the animal research committees of our institution. we used a female swine of kg. an assistant forcep lifted up the fundus of gallbladder to create good visualization of surgical field. the cystic duct was ligated by laparoscopic clip device from assistant port. blunt dissection was performed by pushing the forceps and sharp dissection by monopolar electrocoagulation. results: the fess accomplished the dissection of the gallbladder from the liver bed successfully. two mm forceps had enough grasping and dissecting force and dexterity. the gallbladder was removed from single port site easily. conclusions: this experiment showed that it is feasible to intuitively operate single-site cholecystectomy with fess. in order to realize a pure fess procedure, an additional novel device to create good visualization of the surgical field is necessary for the fess platform. a prototype has already been developed for evaluation in securing the surgical field. the optimal working range, or "sweet spot" of fess is not relatively large. in addressing this issue, the feature of easy setup is being improved to enable more efficient positioning and shifting of the sweet spot for the surgical field. this mechanism could enhance the expansion of procedures suitable for fess. the target procedures of fess are those specifically suitable for single port surgery, such as transanal surgeries and transcervical mediastinoscopic surgeries. intraluminal procedures and natural orifice translumenal surgery (notes), which are not considered suitable for rigid surgical robot, are also good applications of fess. regression of anal and scrotal squamous cell carcinoma (hpv related) with imiquimod index patient is a year old hiv positive homosexual man with anal-scrotal condylomas (ain) initially resected in , then treated with radiation in for recurrence. recurred in with changes severe enough to ''…consider diagnosis of invasive squamous cell carcinoma…''. patient elected trial of imiquimod % cream three times per week to defer recommendation of abdominoperineal resection. imiquimod has no antiviral effect but stimulates interferon and cytokines to suppress hpv subtypes and , among other immune effects. no data exists as to systemic effects of imiquimod. after three months of therapy, lesions had largely regressed with only one specimen showing ''…concern for squamous cell carcinoma in situ…''. patient has elected to continue treatment pending further biopsy. this report is typical of a number of other reports of small numbers of cases of neoplasia regression with imiquimod % cream to include melanoma-in-situ, basal cell cancer of skin and other cutaneous malignancies as well as vin. a second female patient, years old, hiv+ with hpv lesions (ain ) including urethral lesions, is being treated with vulvar application of imiquimod to determine if urethral lesions will regress. there is no fda-approved indication for mucosal application of imiquimod. biopsies are pending at completion of six month trial of imiquiimod. surg endosc ( ) introduction: training in flexible endoscopy remains a critical skill for surgeons, as therapeutic endoscopy procedures continue to evolve and to supplant standard surgical operations. the role of endoscopy across surgical subspecialties is shifting, as endolumenal procedures (like per-oral endoscopic myotomy and endolumenal bariatric interventions) have become commonplace. while surgical residency minimum case volumes are mandated, little is known about the volume of endoscopic procedures surgical fellows participate in. we aimed to characterize the volume of flexible endoscopy cases logged by surgical subspecialty fellows as a measure of endoscopic platform use by surgeons. methods: operative case logs for fellows enrolled in post-graduate training programs participating in the fellowship council were de-identified (no patient or program specific information) and provided for analysis. the case log is an online, mandatory, self-reported collection of all surgeries, procedures and endoscopies performed during fellowship year. all cases listed within the category of "gi endoscopy" in which the fellow designated their role as "primary" surgeon for the procedure were further sorted based on subcategory and linked to the year of fellowship graduation. rigid endoscopy, trans-anal endoscopic procedures, and those in which the fellows roll was "first assistant" were excluded. introduction: complex pancreatic and duodenal injuries due to trauma continue to present a formidable challenge to the trauma surgeon with a described mortality of - % and morbidity of - %. duodenal fistula formation subsequent to failure of attempted primary repair is associated with significant morbidity and mortality. we present the first reported series of four patients with complex trauma-related duodenal injuries who had failure of primary repair which were managed with duodenal stenting. we compared outcomes to a matched case control cohort of patients with trauma related duodenal injuries. the aim of this study is to document our experience with enteral stents in patients with complex duodenopancreatic traumatic injuries. methods: a retrospective review at a level i trauma center identified patients who underwent endoscopically placed indwelling covered metal stents after failure of primary duodenal repair in the form of high output duodenal fistulas. a matched case control cohort was identified including patients with duodenal fistulas who were not treated with stents. drainage volumes were collected and classified according to source and phase of intervention (i.e. admission to fistula diagnosis, to stent insertion, after removal, and until discharge). results: there was a decrease in the mean combined drain output of ml/day (p= . ) after stent placement. when comparing the sum of all output sources, there was a statistically significant difference across phases (p= . ) and "after removal" was significantly less when compared to the reference phase (p= . ). there was also a change in the directionality of the slope for the sum of all drain outputs with an increase of ml/day prior to stent placement compared to a decrease of ml/day (p= . ) after stent placement. the stenting group demonstrated a decrease in mean drain output ( ml/day vs ml/day, p= . ) and increase in distal gastrointestinal output ( ml/day vs ml/day, p= . ). one patient in the stent group required later operative repair. all other patients in the stenting and control group had resolution of their fistulas over time. there were late mortalities in the control group. the stent treated patients demonstrated diversion of approximately ml/day of enteral contents distally. while all patients eventually healed their fistulas, the stent treated patients demonstrated an accelerated abatement of drain outputs when compared to the control cohort, but did not reach statistical significance. indwelling enteral-coated stents appear to be an effective rescue method for an otherwise inaccessible duodenal fistula after failure of primary repair. kevin l chow, md, hassan mashbari, md, mohannad hemdi, md, eduardo smith-singares, md; university of illinois at chicago introduction: esophageal trauma represents an uncommon but potentially catastrophic injury with a reported overall mortality of up to %. the management of iatrogenic and spontaneous perforations have been previously described with well-established guidelines which have been mirrored in the trauma setting. esophageal leaks are the most feared complication after primary surgical management and present a challenge to salvage. there has been increasing reports in the literature supporting the use of removable covered metal stents to treat esophageal perforations and leaks in the non-trauma setting. we present the first reported case series of four patients presenting with external penetrating trauma induced esophageal injuries, complicated by failure of initial primary surgical repair and leak development, successfully managed with the use of esophageal stents. materials and methods: a retrospective review was performed at a level i trauma center identifying four patients who underwent endoscopically placed removable covered metal stents, either by a surgical endoscopist or an interventional gastroenterologist, after failure of primary surgical repair of esophageal traumatic injuries. demographic information, hospital stay, additional interventions, complications, imaging studies, iss scores, and outcomes were collected. results: our cohort consisted of patients with penetrating injuries to the chest and neck with esophageal injuries ( thoracic and cervical esophageal injuries) managed with esophageal stenting after leaks were diagnosed following primary surgical repair. their initial esophageal injuries included grades , and . leaks were diagnosed on average post-operative day . two patients underwent an additional attempted surgical repair and subsequent leak development. esophageal stents were placed under endoscopic and fluoroscopic guidance within days of leak diagnosis. there was resolution of their esophageal fistulas with all patients resuming oral intake (averaging days after stent placement). three patients ( %) required further endoscopic interventions to adjust the stent due to migration or for dilations due to strictures. mortality was %, all patients survived to be discharged from the hospital with average icu length of stay of days. conclusion: the use of esophageal stenting has progressed over the last few years, with successful management of both post-operative upper gastrointestinal leaks as well as benign, spontaneous, or iatrogenic esophageal perforations. while the mainstay of external penetrating traumatic esophageal injuries remains surgical exploration, debridement, and repair with perivisceral drainage; our case series illustrates that the use of esophageal stents is an attractive adjunct that can be effective in the management of post-operative leaks in the trauma patient. results of the ovesco-over-overstitch technique for managing bariatric surgical complications introduction: since , the preferred method of enteral access has been the percutaneous endoscopic gastrostomy tube (peg). accidental removal is a common complication associated with excessive cost and possible significant morbidity. removal prior to days is considered ''early removal.'' early removal has more significant risk associated with it, and can necessitate emergent operation to prevent peritonitis and sepsis. some patients, who do not exhibit signs of peritonitis, may be simply observed. for these patients, peg replacement would typically be delayed - days to ensure closure. this delay results in prolonged npo status and worsened nutritional status. presented below is a case of early accidental removal followed by endoscopic clip closure, and immediate peg replacement. case report: a -year-old male presented after a large left middle cerebral artery infarct. a peg placement was completed without complication. eleven hours after the procedure the patient had pulled the peg tube out of the abdominal wall. at this time the patient appeared to have no abdominal pain and no signs of peritonitis. twelve hours following the accidental removal of his peg tube, the patient was taken back to the endoscopy suite, and an egd was performed. the previous peg site was identified and appeared closed and ulcerated. the mucosal defect was closed with two endoscopic metallic clips. a peg tube was then placed at an adjacent site. the following day, the patient was restarted on trickle feeds and advanced to regular tube feeding over a period of hours. since that time, his peg has been functioning well. discussion: we propose that in the case of early accidental peg removal, the patient should be examined first for evidence of peritonitis. if initial physical exam and radiographic investigation do not reveal peritonitis or significant pneumoperitoneum, the patient should undergo urgent repeat endoscopy. at this time, the gastrotomy can be closed endoscopically via metallic clips and peg can be replaced immediately. tube feeds can be initiated after a - hour period of dependent drainage with serial abdominal exams. introduction: since its inception in , poem has become a viable procedure for the treatment of achalasia and esophageal dysmotility disorders. however many institutions are in the beginning stages of implementing the procedure into their programs. in view of training, we report the successful ability to dissect and identify common landmarks during a poem procedure performed by trainees under supervision in a high volume poem center. methods: posterior poem procedures performed by trainees with experienced proctor guidance during the period between february to july were evaluated for the frequency of identifying the perforating vessels, the presence of sling fibers, and position on the lesser curvature of stomach evaluated by double scoping method during the creation of the tunnel and myotomy for procedure. results: all poem procedures were successfully completed by trainees (gi and surgery fellows). the average length of procedure was minutes. indication for procedure included patients with type achalasia ( %), with type achalasia ( %) and des ( %). average length of myotomy for all procedures was . cm. during these procedures or perforator vessels were identified in ( %) of patients, sling muscle was identified in patients ( %) of patients. myotomy extended to anterior lesser curvature of stomach on double scope exam in % of patients. no patient had a serious complication requiring intervention. conclusion: trainees performing a posterior poem procedure were able to correctly dissect and identify the sling muscle and/or perforating vessels in approximately % and % respectively of procedures. however the myotomy position was correctly placed in all procedures. this indicates that while ideally the sling fibers and perforating vessels should be identified, a correctly positioned myotomy can still be successfully performed by trainees without identification of these landmarks. introduction: gastroparesis is a rapidly increasing problem with sometimes devestating patient consequenses. surgical treatments, particularly laparoscopic pyloroplasty, have recently gained popularity but require general anesthesia, advanced skills and create risk of leaks. peroral pyloromyotomy (pop) is a less invasive alternative but is technically demanding and not widely available. we propose an hybrid laparo-endoscopic collaborative approach using a novel gastric access device to allow a endoluminal stapled pyloroplasty as an alternative treatment option for functional gastric outlet obstruction. methods and procedures: under general anesthesia six female pigs (mean weight kg) had endoscopic placement of or mm intragastric ports (taggs, kansas, usa) using a technique similar to percutaneous endoscopic gastrostomy. a mm laparoscope was used for visualization. endoflip (crospon, inc., galway, ireland) was used to measure cross sectional area (csa) and compliance of the pylorus before intervention, immediately after and at week survival. pyloroplasty was performed using a mm articulating laparoscopic stapler (dextera microcutter). after removing the taggs ports, the gastrotomies were closed by either endoscopic clip, endoscopic suture or suture under laparoscopic vision. the animals were survived for week. after - days, a second laparo-endoscopic procedure was performed to verify healing of the pyloroplasty as well as intraluminal dimensions. at the end of the protocol, animals were euthanized. results: six endoluminal linear stapled pyloroplasty were performed. the mean operative time was min. in all cases, this technique was effective in achieving optimal pyloric dilatation. median pyloric diameter (d) and median cross-sectional area (csa) pre-pyloroplasty were mm ( . - . mm) and . mm ( - mm ). after the procedure, these values were increased to . mm ( . - . mm) and . mm ( - mm ) respectively (p= . the quality of endoscopic examination depends on the quality of endoscopic equipment, experience of the endoscopist and preparation of the patient. contemporarily electronic endoscopes make feasible to transfer image directly to external device which is subsequently linked to computer network and can be transferred further. dynamic image viewed in real time is more accurately interpreted by a physician than a static one. the possibility of simultaneous voice contact makes teleconsultation sterling. the aim of this study was to present our own experience regarding endoscopic teleconsultations. materials and methods: analysis enrolled examinations performed in endoscopic centers located in lesser poland district and in denmark. consultations took place in real time, consulting physicians had more than years of experience in endoscopic procedures and over colonoscopies and therapeutic procedures performed. there were teleconsultations via standard internet connection mb/s. endoscopic centers were equipped with olympus and series linked to video card. each card had its own ip address, and the image was accessible through internet login from anywhere. consulting physicians used computers connected to internet for tracing the image synchronously and giving advice. results: teleconsultations were undertaken in . % of all endoscopic procedures. teleconsultations concerned difficulties in endoscopic image interpretation in cases and decisions regarding further treatment in cases. the consulting physician solved all problems concerning proper endoscopic image interpretation. in cases the elective procedure was rejected. the elective treatment was continued in remaining cases. patients had a complication of polypectomy that was endoscopically treated. conclusions: the opinion of independent consulting physician in difficult clinical cases regarding endoscopic procedures helps to understand the endoscopic image in real time and implicates a decrease in complications after endoscopic procedures. michelle ganyo, md, robert lawson, md; naval medical center san diego introduction: a presacral phlegmon is a contained collection of infected fluid and inflammation within the bony pelvis, posterior to the rectum and anterior to the sacrum, that usually arises as a complication of surgery, malignancy, inflammatory bowel disease, ischemic colitis or perforated viscous. symptoms include low-back pain, pelvic pain and fevers. antibiotics and supportive therapy are the mainstay of treatment. however, if abscess develops, drainage is required usually by trans-gluteal percutaneous and/or surgical methods, both of which are associated with significant morbidity and mortality. endoscopic ultrasound (eus) -guided drainage of perirectal and presacral abscesses is a well described minimally-invasive approach that permits clear definition of anatomy, real-time access to the abscess and creation of an internalized fistula through placement of one or more transluminal stents. however, to date there is no published report describing endoscopic treatment of the more complicated, clinically challenging presacral phlegmon. here we present a case of a symptomatic presacral phlegmon recalcitrant to medical management that was successfully treated with an endoscopically placed retrievable, transmural, lumen-apposing metal stent. case report: this is a case-report of a -year-old, post-partum female who presented with fevers and recurrent lower back pain radiating to her rectum and vagina. her spontaneous vaginal delivery was notable for a second-degree laceration that was primarily repaired at the time of delivery months prior to presentation. her past medical history was otherwise unremarkable. radiographic imaging revealed several perirectal and presacral abscesses that were considered too small for percutaneous drainage. iv antibiotics were started and the largest abscess was targeted for eusguided aspiration. unfortunately, her pain became constant and progressed in severity. a follow-up mri a week later revealed a -cm presacral phlegmon. results: colonoscopy revealed a luminal bulge in the rectum but was otherwise normal. to permit drainage and multiple sessions of endoscopic necrosectomy, a mm lumen-apposing metal stent (lams) was placed transrectally under eus-guidance into the presacral phlegmon. endoscopic debridement with forceps and copious irrigation was performed. over the following weeks the patient reported purulent rectal drainage and resolution of her fevers and pain. repeat endoscopy revealed a normal rectum and no sign of the stent. a follow up mri showed a -cm area of heterogenous tissue in the presacral area. conclusions: although not previously described for management of a presacral phlegmon, lams appears to be a safe and effective, minimally-invasive treatment option. introduction: flexible endoscopy has evolved to include multiple endoluminal procedures such as anti-reflux procedures, pyloromyotomy, and mucosal and submucosal tumor resections. however, these remain technically demanding procedures as they are hindered by the state of flexible technology which has difficult imaging, limited energy devices, no staplers, and cumbersome suturing abilities. an alternative approach is transgastric laparoscopy, which for almost decades has been shown to be a good procedure for pancreatic pseudocyst drainage and full-thickness and mucosal resection of various lesions. we propose to expand the indications of transgastric laparoscopy by using novel endoscopically placed transgastric laparoscopy ports (taggs, kansa, usa) to replicate endoscopic procedures such as endoluminal antireflux surgery. methods and procedures: under general anesthesia female pigs (mean weight . kg) had endoscopic placement of mm-intragastric ports (taggs, kansas, usa) using a technique similar to percutaneous endoscopic gastrostomy. a mm laparoscope was used for visualization. endoflip, (crospon, inc., galway, ireland) was used to measure cross sectional area (csa) and compliance of the gastroesophageal junction (gej) before and after intervention. laparoendoscopic-assited suture plication of the gej was performed using - sutures (polysorb®). once the taggs ports were removed, the gastrotomies were closed by using endoscopic clip. at the end of the protocol, animals were euthanized. results: five laparoendoscopic-assited sewing plication were performed. the mean operative time was , min (endoscopic evaluation: . min, tagss insertion: min, endoflip evaluation+ gej plication: , min, gastric wall closure: min). in all cases, this technique was effective in achieving adequate gej plication. median gej diameter (d) and median cross-sectional area (csa) pre-plication were . mm ( . - . mm) and . mm ( - mm ). after the procedure, these values were decreased to . mm ( . - . mm) and . mm ( - mm ) respectively (p= , ). median distensibility (d) and median compliance (c) pre-plication were . mm /mmhg ( . - . mm /mmhg) and . mm /mmhg ( , - , mm /mmhg). after the procedure, these values were decreased to , mm /mmhg ( . - . mm /mmhg) and . mm /mmhg ( . - . mm /mmhg) respectively (p= , ). no intraoperative events were observed. conclusion: a hybrid laparoendoscopic approach is a feasible alternative for performing intragastric procedures with the assistance of conventional laparoscopic instruments; especially in cases where the location of the intervention limits the access of standard endoscopy or where endoscopic technology is inadequate. further evaluation is planned in survival models and clinical trials. introduction: due to previous manipulation or submucosal invasion, colonic lesions referred for endoscopic mucosal resection (emr) frequently have flat areas of visible tissue that cannot be snared. current methods for treating residual tissue may lead to incomplete eradication or not allow complete tissue sampling for histologic evaluation. our aim is to describe dissection-enabled scaffold assisted resection (descar): a new technique combining circumferential esd with emr for removal of superficial non-lifting or residual "islands" with suspected submucosal involvement/fibrosis. methods: from to , lesions referred for emr were retrospectively reviewed. cases were identified where lifting and/or snaring of the lesion was incomplete and the descar technique was undertaken. cases were reviewed for location, prior manipulation, rates of successful hybrid resection and adverse events. results: lesions underwent descar due to non-lifting or residual "islands" of tissue. patients were % m, % f, and average age (sd ± . yrs). lesions were located in the cecum (n= ), right colon (n= ), left colon (n= ) and rectum (n= ). average size was mm (sd ± . mm). previous manipulation occurred in / cases ( % biopsy, % resection attempt, % tattoo). the technical success rate for resection of non-lifting lesions was %. there was one delayed bleeding episode but no other adverse events. approximately % of patients have been followed up endoscopically to date with no evidence of residual adenoma. conclusions: descar is a feasible and safe alternative to argon plasma coagulation and avulsion for the endoscopic management of non-lifting or residual colonic lesions, providing en-bloc resection of tissue for histologic review. further studies are needed to demonstrate long-term eradication and for comparison with other methods. results: patients underwent fully covered stent placement procedures. indications for stent placement were leak in patients ( sleeve; bypass) and stricture in patients ( bypass, sleeve). five patients had stent migration. three required surgical removal, one patient endoscopic repositioning and one passed the stent per rectum. all eight patients with enteric leak successfully underwent stent placement in conjunction with diagnostic laparoscopy and drainage. all but one of these patients developed an enteric leak perioperative to index procedure. the average duration of stent treatment in these patients was days ( - days). of the patients treated for a stricture, patients ( sleeve, bypass) failed treatment and required subsequent definitive operative revision. average length of time of stent treatment in these patients was days (range, - days) and five had severe intolerance. conclusions: endoscopic stent placement of leak may require multiple procedures and carries the risk of migration; however, this therapy seems to be an effective treatment. failure rates are higher with strictures and are not as tolerated by patients. background: colonoscopy is the most commonly performed endoscopic examination worldwide and is considered the gold standard for colorectal cancer screening. the quality of examination and endoscopic treatment is affected by a number of factors that are verified by recognized parameters such as cecal intubation rate and time (cir, cit), withdrawal time, adenoma detection rate (adr) and polyp detection rate (pdr). advanced endoscopic imaging improves accurate recognition of the nature and variety of pathologic lesions, while the endoscope tips, third eye retroscope and wide-angle endoscopy allow detection of lesions located on the proximal side of the intestinal folds. the aim of the study was to assess the suitability of wide-angle colonoscopy for the detection of colorectal lesions and to analyze the functionality of a special endoscope series regarding cir, cit and withdrawal time. introduction: leak is an uncommon but serious complication of gastrointestinal surgery. when identified post-operatively, percutaneous drains are used to manage abscesses and prevent further peritoneal contamination. if drain position is suboptimal, however, the consequences of persistent leak may necessitate a formal surgical intervention in a hostile abdomen. in select situations, we have utilized natural orifice transluminal endoscopic surgery (notes) methods to enter the abdominal cavity and place/reposition drains under direct endoscopic visualization a part of our comprehensive endoscopic management algorithm for leaks. methods and procedures: a prospectively collected database was queried for patients who had undergone transluminal endoscopic drain repositioning (tedr) as part of multimodal endolumenal therapy for leak (including interventions like defect closure, enteral feeding access, or endolumenal stent placement). inadequate drainage was identified pre-procedurally by undrained fluid collections in conjunction with clinical signs of sepsis. translumenal access was obtained via the leak site and carbon dioxide insufflation was used in all cases. the peritoneal cavity was surveilled and cleared of gross debris by irrigation and suction. intraabdominal drains were located endoscopically and fluoroscopically, grasped with an endoscopic snare or grasper and repositioned adjacent to the leak site to ensure better drainage. results: four patients ( female), average age (range - ), average body mass index (range - ) were managed with tedr as a component of endoscopic treatment of full-thickness gastrointestinal leak. two patients developed leak following revisional bariatric surgery. one patient had an acutely dislodged gastrostomy tube with intraperitoneal leak after multiple laparotomies recently closed with a granulating vicryl mesh. one patient developed a leak at an esophagojejunostomy following total gastrectomy. three patients had adequate drainage after the initial tedr, while one patient required tedr on two occasions. all patients had improved drainage demonstrated by resolution of clinical signs of sepsis and resolution of fluid collections. drains were removed as clinically indicated. conclusion: intraabdominal drains are an essential element in the management of full-thickness gastrointestinal leaks, but are not always able to be adequately positioned percutaneously. transluminal endoscopic drain repositioning via a gastrointestinal defect is a viable option to avoid surgical intervention in an otherwise hostile field and is a novel practical notes application. background: epiphrenic diverticula (ed) arise from increased intraluminal pressures, often secondary to achalasia or another underlying esophageal motility disorder which causes "pulsion" physiology. ed are traditionally thought to contribute to patients' symptoms of regurgitation and dysphagia, and are frequently resected at time of heller myotomy and fundoplication done for treatment of the primary motility disorder. ed excision carries significant risks (staple line leak, pulmonary complications, mortality), and little is known regarding patients with ed and esophageal motility disorder who undergo surgical myotomy without ed resection. the goal of this study was to compare outcomes of patients with ed and esophageal motility disorder who did and did not undergo diverticulectomy at time of myotomy and fundoplication. methods: retrospective analysis of prospectively collected database from to was performed. patients with diagnosis of ed undergoing surgical treatment of symptomatic esophageal motility disorder were included. all patients underwent laparoscopic heller myotomy with toupet fundoplication by a single surgeon at a tertiary referral hospital. patients were stratified according to whether ed was excised or not excised at time of primary surgery. patient-reported symptoms were obtained from pre/post-operative clinic evaluations and mailed surveys during the follow-up period. independent samples t-test and fisher's exact test were used to compare continuous and categorical variables respectively. results: ed was identified in patients prior to surgery. primary diagnoses included achalasia (n = ), nutcracker esophagus (n= ), and diffuse esophageal spasm (n= ). ed was excised in five patients ( . %) and not excised in ten patients ( . %), with no significant difference in frequency of preoperative dysphagia ( % vs. %, p= . ) or regurgitation ( % vs. %, p= . ) between groups respectively. reasons for non-resection included ed was too proximal (n= ), patient/surgeon preference (n= ), and small ed size (n= ). the resection group did not experience any leaks and there were no mortalities in either cohort during the follow-up period. at mean clinic follow-up of days, there was no difference in frequency of residual dysphagia in patients who did or did not undergo ed resection ( % vs. %, p= . ) and neither cohort reported residual regurgitation symptoms. conclusions: this study suggests that leaving ed in place during surgical treatment of an esophageal motility disorder may achieve similar rates of postoperative symptom control. while ed excision in this study did not cause significant excess morbidity, ed resection introduces risk of leak and requires more extensive surgery that may not provide significant benefit to patients. introduction: median arcuate ligament syndrome (mals) has been described in the literature as presenting with a constellation of symptoms including nausea, vomiting, weight loss, and post-prandial epigastric pain. while many of these symptoms are consistent with foregut pathology, a cohort of patients with mals presenting with delayed gastric emptying has not been described in the literature. in this study we report on the possible association of mals with delayed gastric emptying. methods: cases of mal release were collected between and . eight patients were identified who presented with mals and underwent subsequent mal release. all patients underwent laparoscopic or robotic surgery. patients were compiled into a retrospective database and their demographic, symptomatic, imaging, and outcomes data were analyzed. background: laparoscopic fundoplication (lf) is often performed to treat paraesophageal hernia and/or gerd. care is taken to select the right patients for the operation. some patients may not improve, and others experience dysphagia or bloating after surgery. factors associated with patient satisfaction after fundoplication would be helpful during the patient selection process. methods: a retrospective review of a prospectively collected database was performed. queried patients underwent lf from to . non-elective operations and fundoplications after heller myotomy were excluded. of this cohort, patients were included only if they responded to a two-year postoperative quality of life survey. surveys were distributed preoperatively, at three weeks, at one year, and at two years. the surveys include the reflux severity index, gerd-hrql, and dysphagia score. the gerd-hrql asks about patient satisfaction with their current state ( = dissatisfied, = somewhat satisfied, = very satisfied). the cohort was divided according to their answer to this question at two years. demographics and preoperative factors were compared between the groups with kruskal-wallis and fisher's exact tests. univariable and multivariable ordinal logistic regression was performed to identify preoperative symptoms associated with satisfaction at two years. scores on the surveys over time were were also analyzed. results: a total of patients were included in the analysis (dissatisfied = , somewhat satisfied = , very satisfied = ). the only significant demographic or preoperative difference was a high number of paraesophageal hernias in the 'very satisfied' cohort (p = . ). on univariable regression, younger age and paraesophageal hernia predicted satisfaction. several variables negatively predicted satisfaction with an or \ . multivariable regression, controlled for age and hernia type, identified throat clearing, post-nasal drip, and globus sensation as preoperative symptoms less likely to result in patient satisfaction (p = . , . , and . , respectively). subgroup analysis of patients with paraesophageal hernias revealed that patients with bloating preoperatively are less likely to be satisfied at two years. survey scores over time showed all groups improving over three weeks, but while satisfied patients continued to improved, dissatisfied patients symptomatically worsened over time. conclusion: this study confirms previous reports stating atypical symptoms of gerd are less likely to improve after lf. it also shows individuals with paraesophageal hernia tend to do quite well, unless they report bloating preoperatively. patient-centered analysis such as this can be useful when discussing postoperative expectations with patients, and may reveal opportunities to individualize operative approach. objective: the study was performed to assess whether sutured crural closure or mesh reinforcement for hiatal closure yields better results with regards to symptom resolution and recurrence post-operatively. material and methods: a prospective randomized controlled trial was carried out at grant medical college and sir j. j. group of hospitals, mumbai, india. patients were randomized to receive either sutured repair or mesh reinforcement of hiatal closure. outcomes of interest were symptom resolution, quality of life scores and recurrence in the postoperative period. results: patients were recruited for the trial ( -sutured repair, -mesh reinforcement). the two groups were comparable in terms of demographic profiles, symptom severity and findings at esophagogastroscopy and manometry in the pre-operative period as well as size of the hiatal defect measured intra-operatively. post-operatively the mesh repair group had significantly better symptom resolution in terms of early satiety, chest pain and regurgitation (p\ . ) while with respect to heartburn, dysphagia and post-prandial pain there was no significant difference between the improvements demonstrated. improvement in quality of life scores after either procedure was not significantly different. recurrence was higher in the suture repair group ( vs , p. ). recurrence lead to poorer symptom severity scores as well as quality of life scores and one patient underwent re-operation. the change in the symptom severity score from baseline after the procedure at months in the subgroup population. conclusion: mesh reinforcement results in a reduced rate of recurrence and offers excellent symptom control in the short-term without a rise in complications when compared to sutured repair for the closure of hiatal defects in laparoscopic hiatal hernia repairs. material and methods: in a period from to , patients underwent laparoscopic resection ( -gastric resection, -duodenal resection), using different techniques. all patients were investigated with upper gi endoscopy, eus and abdominal contrast-ct, which allows us to get the complete evaluation of tumor, including size, location, type of growth and the gi layer. based on the findings the decision on the type of resection was made. the majority of resections were wedge or partial resections, performed using endoscopic steplers or using ultrasound scissors followed by double-suturing of gatro/duodenotomy. in the cases of tumor location on the posterior gastric wall we mobilized the the greater curvature to get a direct approach to the tumor with extraluminal growth. in the cases with intraluminal growth we used transgastric approach with small , cm incision on the anterior gastric wall for endoscopic stepler. technically the most complex procedures were in the cases of tumor location close to anatomically narrow places and muscle sphincters (gastroesophageal junction, pylorus, duodenal bulb, duodenal flexure), with high risk of stenosis and dysfunction of anatomical sphincters. in such cases we used «lifting-technique» in which we dissect serous and muscle layers circumferentially around the tumor making partial enucleation of lesion followed by total resection preserving almost all normal tissue with minimal suturing and deformity at the site of surgery. ( : ), mean age was . years (sd ± . ), patients ( %) had mis. the type of reconstruction was predominantly with a "pull-up" technique (n = , . %) followed by the kirschner-akiyama procedure (n = , . %), stapled gastroplasty was performed in patients. all the anastomosis were performed at the level of the neck and only one of the patients had a stapled anastomosis, mean operative time was min (sd ± min) including resection of the specimen. primary neoplasms were predominantly hypopharynx (n = , . %), distal esophagus (n = , %), cervical esophagus (n = , . %) and thoracic esophagus (n = , . %). histologic types were mainly squamous cell carcinoma (n = , . %) and adenocarcinoma (n = , . %). mean of hospitalization days was . (sd ± . ). no complications were observed in patients and major complications (dindo-clavien ≥iiib) were found in patients. anastomotic leak was present in patients ( . %) and perioperative mortality ( days) was . %. progressive shift to laparoscopic surgery was evidenced through the years ( - : . %, - : . % and - : . %; p = . ) and reduction in major complications (p = , ) was observed. anastomotic leaks (p = , ) and perioperative mortality (p = . ) did not show significant differences in the present study. conclusions: results in our center show that major complications decrease with time after application of minimally-invasive surgery and no differences in anastomotic leaks and mortality were seen. current data has lead us to abandon open total esophagectomy as a first-choice procedure. introduction: minimal invasive three-fields esophagectomy for minimal invasion is the surgical standard for oncological procedures and benign diseases. cervical dissection has a risk of to % in some series, of, lesion or paralysis of the rnl, but the standard in mckeon approach is %. a high level of suspicion is needed because this type of lesion has an impact on postoperative evolution and the hospital stay. main: to describe three cases of rnl post esophagectomy paralysis in three planes by least invasion. methods: in a period of years, january to june , esophagectomies for bening disease were performed. three patients ( males female) with diagnosis of terminal achalasia and stenosis secondary to caustic ingestion consulted at the minimal invasion service fundcacion valle del lili. they were schedualed for minimal invasive three fields esophagectomy, one patient without complications and early discharge ( postoperative day) but occasional dysphagia, the other two required early reintubation after de surgery with ards, patient requiered tracheostomy, the second patient could be extubated after days but with occasional dysphagia. all three had mild hoarseness after surgery. the patient who required tracheostomy was decannulated at days without complication. results: the three patients underwent endoscopy without complication in the cervical anastomosis stenosis or disorder in the emptying of the gastric tube, swallowing study without alteration and laryngoscopy with paralysis of the left vocal cord. these patients went to speech therapy with total paralysis recovery at months corroborated with laryngoscopy, without dysphagia or hoarseness. conclusion: rnl innervates the larynx and upper esophageal sphincter, therefore lesion or paresis causes symptoms such as hoarseness, dysphagia, difficulty swallowing, aspiration, difficulty in coughing, pneumonia and ards. injury has a predecessor factor in pulmonary complications and prolongation of the hospital stay. % of these patients may require some surgical procedure to restore the function of rnl. noninvasive monitoring of the laryngeal nerve decreases the risk of injury. philip case report: multiple esophageal diverticula associated with achalasia introduction: achalasia is well defined disorder of increased lower esophageal sphincter tone ( ). epiphrenic esophageal diverticulum are a rare disorder believed to result from increased intraesophageal pressure often in conjunction with a motility disorder causing functional outflow obstruction. they are a pulsion-type pseudo-diverticulum with mucosal bulging most frequently from the right posterior esophageal wall ( ) . we present a very rare case of achalasia associated with multiple esophageal diverticula successfully treated with laparoscopic heller myotomy with dor fundoplication. case presentation: a year old woman presented with years of dysphagia, chest discomfort, regurgitation, and weight loss. esophagoscopy showed a patulous esophagus with multiple esophageal diverticula (figure ). barium esophogram demonstrated esophageal diverticula in the distal esophagus and delayed clearance of esophageal contrast (figure ). high resolution monometry revealed a hypertensive mean les, an aperistaltic body on of wet swallows, and panesophageal pressurization in of wet swallows -consistent with type ii achalasia by chicago classification ( ). we performed a laparoscopic heller myotomy with dor fundoplication. the myotomy was extended cm above the gasgtroesophageal junction and cm onto the gastric cardia. an anterior diaphragmatic defect with a moderate type hiatal hernia was repaired with two sutures, ensuring to not impinge the esophagus (figure ). at weeks post operatively the patient reports excellent results. her dysphagia and chest discomfort have entirely resolved. her eckhardt score improved from seven preoperatively to one post operatively. discussion: type ii achalasia is successfully treated in the majority of cases with laparoscopic heller myotomy and partial fundoplication ( ). however, esophageal diverticula typically require both myotomy as well as diverticulectomy for successful treatment ( ) . there is little experience with the surgical management of multiple esophageal diverticula. we propose a two stage surgical approach for these patients. we reason that the risk of esophageal leak or stenosis in the case of multiple esophageal diverticulectomies out weighs the proposed benefit. indeed epidemiologic studies indicate that the majority of esophageal diverticula are asymptomatic ( ) . in the event the patient remains symptomatic after myotomy a second stage operation with diverticulectomies would be possible. this single experience suggests that diverticulectomy may not be necessary in the case of multiple diverticula associated with achalasia. instead, treatment may be directed at relieving the functional obstruction responsible for the symptoms by performing laparoscopic heller myotomy with dor fundoplication. takahiro kinoshita, md, facs, masanori tokunaga, md, akio kaito, md, masahiro watanabe, md, shizuki sugita, md; national cancer center hospital east, japan objective: the optimal surgical approach for siwert type ii cancer is still controversial due to the anatomical complexity of the region. potential advantages of laparoscopic transhiatal approach have not been fully investigated. methods and procedures: we retrospectively analyzed consecutive patients with siewert type ii cancer who underwent laparoscopic transhiatal resection. indication of surgery is patients with siewert type ii cancer with less than cm esophageal invasion. regarding the extent of resection, basically proximal gastrectomy with the lower esophageal resection was selected, aiming at preservation of gastric reservoir function. in terms of reconstruction after proximal gastrectomy, double-tract method was performed. intraoperative peroral endoscopy was routinely employed for determination of the appropriate resection level of the stomach. esophagojejunostomy was employed by overlap method using a mm linear stapler. in order to obtain a wider operative field in the lower mediastinum, the diaphragmatic crus was dissected to widen the esophageal hiatus. results: in patients ( males and females), median operation time was minutes, and estimated blood loss was g. the rate of surgical morbidity was %, and that of anastomotic leakage was %. there was no mortality. the mean length of proximal margin was mm, and no positive margin was recorded. the -and -year overall survival rate was . % and %, respectively. conclusions: laparoscopic transhiatal resection for siewert type ii cancer is technically challenging, but appears feasible and safe when performed by an experienced surgical team. a largescale prospective study is necessary for final conclusion. introduction: mesh use for reinforcement of primary crural closure is controversial. synthetic mesh use poses a risk of erosion but there is no evidence that non-synthetic mesh is useful to minimize the risk of hernia recurrence. we evaluated a fully bioresorbable mesh made from poly- -hydroxybutyrate (p hb) for crural reinforcement after para-esophageal hernia (peh) repair. the aim of this study was to evaluate the safety and efficacy of p hb mesh at the hiatus in patients undergoing peh repair. this was a review of prospectively collected data on consecutive patients that had repair of a peh with reinforcement of the crural closure with p hb mesh. to be considered a peh at least % of the stomach was herniated into the chest. a collis gastroplasty or crural relaxing incision was added for short esophagus or crural tension when necessary. routine follow-up consisted of esophagogastroduodenoscopy (egd) at months for patients that had a collis gastroplasty and a barium upper gi study (ugi), high resolution manometry (hrm) and ph test in all patients at months. a hernia of any size identified during objective follow-up testing was considered a recurrence. overall, there was a significant difference in mean measured tension between the three subjective suture ratings by the surgeons. however, there was substantial variability and overlap amongst the surgeon's ratings (figure) . the tension necessary to approximate the crura during peh repair can be objectively measured and as expected increases progressively with anterior movement up the hiatus. while there was some correlation between a surgeon's subjective assessment of the tension necessary to bring the crura together and actual measured tension, there was wide variability and imprecision from one stitch to another. objective tension measurement may provide a more reliable assessment of when excessive force is being used to re-approximate the crura and potentially improve peh recurrence rates. ahmed introduction: paraesophageal hernia repairs are increasing in prevalence, and unfortunately carry a high recurrence rate. consequently, reoperation is expected to increase in frequency. published data on the outcomes of recurrent paraesophageal hernia (rpeh) repair is very limited. because of the technical difficulties of revisional surgery, we hypothesize that laparoscopic revisional paraesophageal hernia repairs are associated with high perioperative morbidity and poor patient outcomes. methods: all rpeh repairs performed by the foregut surgical service at our institution from to were reviewed. patients were included if their index operation was a true pehr (initial type hiatal hernia repairs were excluded, as well as multiply recurrent hernias). demographics, medical and surgical history, and operative notes from the index surgery were reviewed. details from standardized pre-operative symptom assessment, objective testing and operative details for the revisional surgery were collected. patients were routinely offered month post-operative upper gastrointestinal contrast evaluation. postoperative outcomes included a standardized symptom assessment and results of objective testing at any time after surgery. results: twenty six patients were identified who underwent repair of rpeh. demographic, operative and perioperative data was available for all patients (table ) . twenty four patients underwent followup symptom evaluation (two were lost to follow-up after the initial hospitalization). sixteen patients underwent follow-up objective testing by radiographic evaluation with contrast, endoscopy or both. these subgroups were used to calculate symptomatic and objective outcomes (table ) . conclusion: reoperative laparoscopic surgery for recurrent paraesophageal hernias is technically challenging as evidenced by long operative times. despite this, perioperative outcomes at a high volume center are good, with low morbidity and no mortality. importantly, symptomatic outcomes for this difficult problem are excellent. introduction: hypotension of the lower esophageal sphincter (hles) and the presence of hiatal hernia (hh) have both been associated with gastroesophageal reflux disease (gerd). the exact likelihood with which a hles or a hiatal hernia predict gerd continues to be defined. we hypothesize a synergistic interaction in those with hles and hh in predicting gerd as defined by a positive ph study. methods and procedures: between and , consecutive patients presenting to a surgical practice with symptoms most concerning for gerd, without prior antireflux surgery were evaluated by high resolution manometry (hrm), esophagogastroduodenoscopy (egd), videoesophagography (veg) and an ambulatory ph study. hles was defined as residual les pressure of\ mmhg, hh was defined as having been noted and measured by the radiologist, these were further categorized into any hh, - cm, [ - cm background: while clinical outcomes have been reported for antireflux surgery, there is limited data on postoperative outpatient encounters and their associated costs. the aim of this study is to evaluate the utilization of healthcare and its associated costs during the -day postoperative period following antireflux surgery. methods: we analyzed data from the truven health marketscan® research databases. patients ≥ years with an icd- procedure code or cpt code for antireflux surgery and a primary diagnosis of gerd during - were selected. only patients with continuous enrollment six months prior to the date of surgery and -days after surgery were analyzed. patients with a diagnosis of esophageal cancer or achalasia during the six-month period prior to antireflux surgery, a length of stay [ days following index procedure, a capitated plan, or patients who underwent emergency surgery were excluded. outpatient endoscopy was defined using icd- and cpt codes, and related readmission was defined by clinical classification software. introduction: the development of postsurgical gastroparesis following nissen fundoplication is poorly understood. in this study, we analyze the development of gastroparesis requiring intervention and other subsequent procedures following fundoplication and paraesophageal hernia (peh) repair procedures in the state of new york. methods: using a comprehensive state-wide administrative database (sparcs), we examined all in-patient and outpatient records for adult patients who underwent fundoplication or peh repair as a primary procedure for the treatment of gerd between the years of - . patients with an initial gastroparesis diagnosis were excluded from the analysis. through the use of a unique identifier, each patient was followed until for the subsequent diagnosis of gastroparesis or reoperation. surgical procedures for the treatment of gastroparesis included pyloroplasty, pyloromyotomy, or gastroenterostomy procedures. multivariable logistic regression models were used to identify independent predictors for having subsequent reoperation. results: a total of , patients were analyzed. this included , fundoplication patients ( . %) and , ( . %) with peh repair. in the fundoplication group, ( . %) patients had a follow-up diagnosis of gastroparesis or secondary procedure. ( . %) of the patients who underwent a primary peh repair procedure had a follow-up procedure or gastroparesis diagnosis (table ) . mean time to follow-up procedure or diagnosis was . years for the fundoplication group and . years for the peh repair group. the majority of the follow-up procedures in the fundoplication group were revisional procedures (fundoplication or peh repair) (n = , . %), while ( . %) patients were newly diagnosed with gastroparesis and/or underwent a secondary procedure for its treatment. conclusion: fundoplication and peh repair procedures have a relatively low post-operative incidence of gastroparesis following initial procedure for treatment of gerd. secondary fundoplication or peh repair was more commonly performed compared to any of the surgical procedures for gastroparesis for both procedures. further analysis of association with subsequent procedures is needed. during this procedure, gastro-esophageal reflux was evaluated and assigned to severe, moderate and slight category. if the reflux was observed slightly up to cervical esophagus, the case was assigned to moderate category. if the reflux was observed intensely up to cervical esophagus, the position was returned to head high position for the safety and the case was assigned to severe category. the anti-reflux surgery was considered in the moderate and severe categories. results: we have performed laparoscopic nissen procedure in cases. the mean operation time was min. the outcome was assessed by reflux test performed on - postoperative day, and the results showed the reflux was disappeared in every cases. median follow-up period of this study was months ( - months). in cases ( . %) ppi was restarted before months after the anti-reflux surgery. in cases ( . %) ppi was restarted after the anti-reflux surgery during the whole follow-up period of this study. the bmi of the patients had no relationship to the needed restart of ppi. to evaluate the degree of esophagitis objectively before and after the anti-reflux surgery we designed "the esophagitis score". in this scoring method, a number from - was assigned according to the degree of esophagitis along with the la classification. the results of the study have shown that the reflux esophagitis was improved obviously after the anti-reflux surgery even in the ppi restarted group (p. ). discussion: the number of gerd patients who needed anti-reflux surgery seems to be so high. to extract the patients who needed it remarkably is important. the anti-reflux surgery is most effective for the patients who really have the obvious reflux. reflux test is feasible because of its convenience and visual effects for the patients. the results of the laparoscopic nissen fundoplication were good and satisfied by the patients mostly. surg endosc ( ) :s -s introduction: fundoplication at the time of giant paraesophageal hernia repair is controversial. the proposed advantages are better reflux control and lower recurrence. disadvantages include fundoplication specific complications, might be unnecessary and may not decrease recurrence. we retrospectively reviewed giant paraesophageal hernia repairs (peh) with two point gastropexy in the fundus and body, and no antireflux procedure. data collected is postoperative gerd symptoms, postoperative proton pump inhibitors (ppis) therapy and recurrence. methods: a retrospective review of patients who underwent repair of giant peh from to december of . giant was defined as a hernia with % or more of the stomach above the diaphragm. follow up consisted of upper gi (ugi) study one year postoperatively and reflux symptom questionnaire. patients were followed every months in the surgery clinic and a ppi wean was initiated at the second postoperative visit. the primary outcome we evaluated was discontinuation of ppis. in addition, we utilized a standardized reflux scale and recurrence rates collected. chi-squared was used for statistical analysis. background: gastroesophageal reflux disease (gerd) is a highly prevalent disorder with a multitude of treatment options ranging from lifestyle modifications and medical management to surgical options. despite the numerous treatments available, there is still debate over which approach is most appropriate and effective for patients. this study aims to examine the effect of robotic hiatal hernia repair (rhhr) with the novel addition of esophagopexy in patients with gerd. methods: a single institution, single surgeon, prospectively maintained database was used to identify patients who underwent rhhr with a partial fundoplication and concomitant esophagopexy for gerd from november to july . patient characteristics, operative details and postoperative outcomes were analyzed. primary endpoint was resolution of subjective gerd symptoms and discontinuation of proton pump inhibitor (ppi). recurrence of hiatal hernia was a secondary endpoint. results: eleven patients were identified meeting the inclusion criteria (rhhr + esophagopexy) with a mean follow-up of . weeks ± . weeks. in regards to the rhhr, % underwent a partial fundoplication and the additional % underwent a re-do wrap. this patient cohort was . % female with a mean age of . ± . years. preoperative esophagogastroduodenoscopy (egd) was performed in % of patients with the study showing a hiatal hernia in . %, gastritis in . % and esophagitis in . % of patients. manometry was performed in . % of the patients showing % of these patients with esophageal dysmotility. esophagograms and ph studies were performed preoperatively in . % and . % of patients respectively. preoperatively, % of patients had a documented diagnosis of gerd and were taking a ppi and/or h blocker. after rhhr with esophagopexy, . % of patients had resolution of their gerd symptoms while . % (n = ) remained symptomatic. however, one of two patients reported a subjective decrease in symptom severity following the procedure. despite resolution of symptoms, . % remained on ppis. another % switched to h blockers and one patient discontinued all antisecretory therapy. none of the patients experienced recurrence of their hiatal hernia. conclusion: based on our data, rhhr with esophagopexy results in resolution gerd symptoms in over % of symptomatic patient. in patients with hiatal hernias and gerd, rhhr with esophagopexy does lead to resolution of symptoms, however, the majority of patients remained on ppis. long-term follow up is needed to investigate whether these patients are able to discontinue ppis and remain symptom free. chaya shwaartz, nadav zilka, mustapha siddiq, yuri goldes, md; sheba medical center, israel background: d gastrectomy for gastric carcinoma is a well-established procedure in patients undergoing surgery for gastric cancer and is the standard of care in our institution. reduced pain, early ambulation, and better cosmetics are some of the benefits of minimally invasive surgery for early gastric cancer. we aimed to describe our experience in laparoscopic d gastrectomies undertaken by a single surgeon in our institution. methods: this is a single-center retrospective review of prospectively collected d gastrectomies performed by a single surgeon. between november and february , laparoscopic subtotal/total gastrectomies were performed at sheba medical center, a tertiary center for forgut cancer. clinicopathological characteristics of the patients, surgical performance, postoperative outcomes and pathological data were collected. results: forty-five patients underwent laparoscopic gastrectomy. of these, had subtotal gastrectomy and had total gastrectomy. the median age in our series ( - ). most of the patients in our series had early gastric cancer (t - ) ( %). the mean average of dissected lymph nodes was ± . the mean operative time was ± . the postoperative complications, classified using the clavien-dindo classification. severe complications ([ cd iiia) rate was %. conclusions: laparoscopic d gastrectomy for invasive gastric cancer is safe and feasible when carried out in high-volume centers by an experienced surgeon as part of a multidisciplinary team with careful case selection and appropriate high-quality postoperative support. minimally invasive management of diaphragmatic hernias after esophagectomy: a case report introduction: esophagectomy is a common treatment for both benign and malignant pathologies of the foregut. hiatial paraconduit hernias are rare complications following esophagectomy. in this study, we review our experience with these rare diaphragmatic hernias. methods: a retrospective analysis of all patients presenting with hiatial hernia after esophageal resection at the university of oklahoma health science center between and was performed. data was abstracted from the medical record for evaluation and included demographics, symptoms, repair techniques and outcomes. no patients were excluded. results: a total of ten patients were identified to have paraconduit hernias. during this time interval, there were a total of esophageal resections performed. all patients had esophagectomy for malignant disease. seven of the patients have undergone surgery. two patients are asymptomatic and are being followed at their request, and one patient is pending elective correction. of the seven patients who underwent surgery, the median age was , with males and two females. six of the seven patients underwent minimally invasive ivor lewis esophagectomy and one had an open mckeown procedure. the median time from esophagectomy to hernia repair was months, with range from month to months. the most common presenting complaint was abdominal pain and nausea. one patient was noted to have a paraconduit hernia on postoperative day and taken to surgery for repair during the hospitalization. there was one death in a patient who presented with necrosis of the small bowel. the remaining patients all had laparoscopic approach. one patient required a hand port to reduce incarcerated colon and one patient was noted to have a cecal perforation during port closure requiring repair. all patients had herniated colon, with small intestine or pancreas herniation noted in three. repair was performed by reducing the viscera, a left phrenic relaxing incision, closure of the hiatus around the conduit and then closure of the diaphragmatic defect with mesh. at median follow up of months, there are no recurrences. conclusion: hiatal paraconduit hernias are becoming a frequent finding among survivors of esophageal cancer surgery. our study demonstrates that there is a propensity for patients who undergo minimally invasive esophagectomy to develop these hernias. the vast majority of patients can undergo laparoscopic repair. our recommendation is to perform a diaphragmatic relaxing incision and liberal use of mesh. early results appear to be favorable regarding recurrence. aim: there have been several reports illustrating the safety and efficacy of various surgical techniques in performing laparoscopic esophagojejunostomy (ej). this study aims to compare two established methods of ej anastomosis -circular stapling with purse-string suture ("lap-jack") and linear stapling technique -in laparoscopic total gastrectomy. methods: patients diagnosed with gastric cancer underwent intracorporeal ej anastomosis in laparoscopic total gastrectomy from january, to october, . cases used the circular stapler with purse-string "lap-jack" method, and patients used the linear stapling method for ej anastomosis. were matched using propensity scores, and retrospective data for patient characteristics, surgical outcome, and post-operative complications was reviewed. the two groups showed no significant difference in age, bmi, or other clinicopathological characteristics, and there was no conversion to an open procedure. after propensity score matching analysis, the linear group had significantly shorter operating time ( . ± . vs . ± . , p≤ . ) and more sufficient proximal margin ( . ± . vs . ± . , p = . ). no significant difference was found in estimated blood loss, retrieved lymph node, hospital stay, and time for first flatus. there was no postoperative mortality. early postoperative complication of the circular and linear group occurred in ( . %) and ( . %, p = . ) patients respectively. ej leakage occurred in ( . %) cases from each groups, with ( %) case from both group needing radiologic or surgical intervention. no other significant difference in early complication was found. late complication was observed in ( . %) cases (circular = linear = , p = . ) with ej anastomosis stricture in the linear group, but there was no statistical significance. conclusion: both circular stapling and linear stapling techniques are feasible and safe in performing intracorporeal ej anastomosis during laparoscopic total gastrectomy. linear-stapling technique had more sufficient proximal margin and shorter operating time. there was no significant difference in anastomosis related complication between the two groups. masahiro watanabe, masanori tokunaga, akio kaito, shizuki sugita, takahiro kinoshita; national cancer center hospital east, gastric surgery division background: although the current standard treatment for advanced gastric cancer (agc) is open gastrectomy, laparoscopic gastrectomy (lg) is increasingly performed, especially in the east. however, it is a technically demanding procedure, and the feasibility remains unclear. the aim of the present study was to clarify the feasibility of lg for agc. patients and methods: the present study included patients who underwent lg for agc between and . the indication of lg has gradually expanded in our institute, and is currently any stage gastric cancer except for gastric cancer obviously invading adjacent organs or gastric stump carcinoma. we retrospectively reviewed short-and long-term surgical outcomes of the patients. results: male/female ratio was : , and median age (range) was ( - ) years. distal gastrectomy was most frequently performed ( %), followed by total gastrectomy ( %). median operation time and intraoperative blood loss was ( - ) minutes and ( - ) g, respectively. clavien-dindo grade iii or more complication rate was . %. with a median followup period of months, the -year recurrence free survival rates of pstage ii and iii patients were % and %, respectively. conclusion: the outcomes of lg for agc are satisfactory, provided that an experienced team performs the surgery. introduction: the present study aims to evaluate the predictive value of indocyanine green (icg) for the detection and prevention of anastomotic leak following esophagectomy. anastomotic leak is a highly morbid and potentially fatal complication of esophagectomy. ensuring adequate perfusion of the gastric conduit can minimize the risk of postoperative leak. intraoperative evaluation with fluorescence angiography using icg offers a dynamic assessment of gastric conduit perfusion, and can guide anastomotic site selection. methods: a search of electronic databases medline, embase, scopus, web of science and the cochrane library using the search terms "indocyanine/fluorescence" and esophagectomy was completed to include all english articles published between and august . articles were selected by two independent reviewers based on the following major inclusion criteria: ( ) esophagectomy with gastric conduit reconstruction; ( ) use of fluorescence angiography with indocyanine green to assess perfusion; ( ) age ≥ years; ( ) sufficient outcome data for the calculation of leak rates and ( ) sample size ≥ . the quality of included studies was assessed using the quality assessment of diagnostic accuracy studies- . results: our literature search yielded potential studies, of which studies were included for meta-analysis after screening and exclusions. there were eleven prospective and three retrospective studies. the pooled anastomotic leak rate when icg was used was found to be %. pooled sensitivity and specificity for leak detection were . ( . - . ) and . ( . - . ), respectively. when studies involving intraoperative modifications were removed, pooled sensitivity and specificity were only marginally changed to . ( . - . ) and . ( . - . ), respectively. the diagnostic odds ratio was found to be . ( . - . ) across all studies and . ( . - . ) when intraoperative interventions were excluded. only three trials included a control group, giving a sample size of . in studies with a comparator group, icg was associated with an % reduction in the risk of anastomotic leak [or: . ( . - . )]. conclusions: in non-randomized trials, the use of icg as an intraoperative tool for visualizing vascular perfusion and conduit site selection, is promising. however, poor data quality and heterogeneity in reported variables limits cross-study comparisons and generalizability of findings. randomized, multi-center trials are needed to account for independent risk factors for leak rates and to better elucidate the impact of icg in predicting and preventing anastomotic leaks. objective: robotic assistance for bariatric surgery represents a novel application of a rapidly emerging technology. its safety and efficacy remains primarily characterized by smaller, singleinstitution studies. in this investigation, the influence of robotic assistance on short-term perioperative outcomes is contrasted with the more established primary multi-port laparoscopic approach for patients undergoing roux-en-y gastric bypass (rygb), using data from a national bariatric database. methods: a retrospective analysis of , robotic-assist and , laparoscopic rygb patients from the metabolic and bariatric surgery accreditation and quality improvement program national database were reviewed for differences in patient characteristics and short-term outcomes. on bivariate analysis, variables associated with primary outcomes of -day reoperation, readmission and reintervention were imputed into multivariate analyses to determine independent significance. results: robotic-assist bypass patients were older (p\. ), had a higher prevalence of comorbidities and had concomitant operations more frequently performed during surgery (p\. ). on bivariate analysis, robotic-assist patients had a higher rate of readmission than laparoscopic patients ( . % vs. . %; p=. ), but no differences in -day reoperation ( conclusion: robotic-assistance does not confer an increased rate of morbidity and mortality after rygb, and represents a feasible surgical modality for the surgeon willing to adopt the technology and accept its limitations. alicia m bonanno, md, brandon tieu, md, farah husain, md; oregon health and science university introduction: marginal ulcer is a common complication following roux-en-y gastric bypass with incidence rates between and %. most marginal ulcers resolve with medical management and lifestyle changes, but in the rare case of a non-healing marginal ulcer there are few treatment options. revision of the gastrojejunal (gj) anastomosis carries significant morbidity and mortality with complication rates ranging from to %. thoracoscopic truncal vagotomy (ttv) may be a safer alternative with decreased operative times. the purpose of this study is to evaluate the safety and effectiveness of ttv in comparison to gj revision for treatment of recalcitrant marginal ulcers. methods and procedures: a retrospective chart review of patients who required surgical intervention for non-healing marginal ulcers was performed from st september to st september . all underwent medical therapy along with lifestyle changes prior to intervention and had preoperative egd that demonstrated a recalcitrant marginal ulcer. revision of the gj anastomosis or ttv was performed. data collected included operative time, ulcer recurrence, morbidity rate, and mortality rate. statistical analysis was performed using t-test and fischer's exact test. results: a total of fifteen patients were identified who underwent either gj revision (n= ) or ttv (n= ). there were no -day mortalities in either group. mean operative time was significantly lower in the ttv group in comparison to gj revision ( . ± vs. . ± minutes respectively, p= . ). recurrence of the ulcer was not significant between groups and occurred following gj revisions and ttv. overall complication rate was not significantly different with % in the gj revision group and % in the ttv group. complications included anastomotic leak ( gj), anastomotic stricture ( gj), aspiration ( ttv), dysphagia ( gj and ttv), and dumping syndrome ( gj). conclusions: our results demonstrate that thoracoscopic vagotomy may be a better alternative with decreased operative times and similar effectiveness. however, further prospective observational studies with a larger patient population would be beneficial to evaluate complication rates and ulcer recurrence rates between groups. we present a case of a -year-old female with a history of thyroid cancer who initially presented to an outside hospital complaining of reflux, abdominal pain, early satiety, and -pound unintentional weight loss. endoscopy demonstrated a cm pre-pyloric mass; with initial biopsies of the mass demonstrating only gastric mucosa. endoscopic ultrasound and fna of the lesion also failed to elucidate its pathology. due to the pyloric location of the mass and inability to rule out invasive malignancy, we recommended a robotic-assisted transgastric submucosal resection with possible distal gastrectomy. intraoperatively we found a -degree circumferential pre-pyloric exophytic sessile tumor. frozen sections suggested a benign papillary tumor therefore we proceeded with submucosal resection. the resulting mucosal defect and gastrotomy were closed primarily with absorbable suture. final pathology showed the tumor to be a tubulovillous adenoma with high grade dysplasia arising against a background of intestinal metaplasia. the resection margins were negative for dysplasia. the postoperative course was complicated by a minor leak which did not require operative intervention and subsequent gastric outlet narrowing which required endoscopic dilation and feeding tube placement. however, the patient has recovered well and has advanced to diet as tolerated. gastric adenoma has a prevalence of . - . % in the western hemisphere. the risk of carcinomatous transformation in gastric adenomas is related to size, degree of dysplasia, and villosity. gastric adenomas are considered precancerous lesions. pre-operative pathologic diagnosis of dysplasia is often elusive as biopsies will often miss or under-grade the lesion. guidelines advocate for complete resection with either endoscopic submucosal dissection or surgical resection depending on surgeon preference and local expertise. endoscopic resection has been shown to be safe and efficacious in the removal of adenomas with good long-term outcomes. in this case the pathology of the lesion was unclear after multiple unsuccessful biopsies and required a surgical diagnosis to rule out invasive malignancy. management of gastric adenomas, while rare, may require a multidisciplinary approach between surgical endoscopy, minimally invasive surgery, and surgical oncology to achieve local control in an oncologically sound manner. we show that transgastric submucosal resection can be achieved in a minimally invasive fashion using robotic assistance. objective: parahiatal hernia is a rare type of diaphragmatic hernia with incidence of . - . %. para-hiatal hernias arises lateral to the left crural musculature adjacent to but separate from the oesophageal diaphragmatic hiatus. in view of its rare occurance and little clinical suspicion, it is almost never diagnosed clinically. the current case report is intended to depict the clinical profile of an intraoperatively diagnosed para-hiatal hernia and feasibility of laparoscopic repair of parahiatal hernias. method: laparoscopic fundoplication is frequently performed at grant medical college and sir j. j. group of hospitals, india. during one such case intraoperatively para-hiatal hernia was diagnosed. discussion: primary or true parahiatal hernias occur as a result of a congenital weakness and secondary defects follow hiatal surgery. the primary treatment of para-hiatal hernia is mesh-plasty. this is coupled with fundoplication in cases of large hernia and those symptomatic for gastroesophageal reflux disease. laparoscopic repair of these uncommon hernias is safe, effective and provides all of the benefits of minimally invasive surgery. conclusion: due to its rare occurrence, knowledge about this condition among laparoscopic surgeons is important to avoid diagnostic dilemma. knowledge about its management aids intraoperatvely to avoid performing incomplete procedure. introduction: extended indications of endoscopic resection for early gastric cancer (egc) have been widely accepted. according to current japanese guidelines, additional gastrectomy with lymph node dissection (lnd) is recommended for patients proven to have potential risks of lymph node metastasis (lnm) on histopathological findings. on the other hand, the frequency of lnm in these patients is exteremely low. the aim of this study was to elucidate the accurate risk of lnm based on the number of risk factors (rf) for possible lnm, and to compare the stratified risk of lnm with predicted risk from additional radical resection. methods and procedures: we enrolled egc patients who did not meet absolute or extended indications of endoscopic resection, and investigated the risk stratification of lnm according to the total number of lnm rfs described below; ( ) sm , ( ) lymphatic vessels invasion, ( ) undifferentiated adenocarinoma and [ mm in diameter, and ( ) [ mm in diameter and ulcer formation. we compared the stratification risk to the surgical risk that was calculated based on the japanese national clinical database (ncd) risk calculator in patients with additional gastrectomy after esd. results: the total number of lnm rfs and frequency of lnm were significantly correlated ( / rf; . %, rfs; . %, rfs, . %, rfs, . %; p. , fischer exact test). the estimated frequency of lnm was found to be lower than the predicted value of in-hospital mortality rate based on ncd in . % of / rf-patients who underwent additional gastrectomy with lnd after esd. the present study suggested that some patients must be over-indicated for additional gastrectomy with lnd, and no additional surgical treatment or less invasive surgery, such as local lnd (sentinel node navigation surgery or lymphatic basin resection), might be indicated for some patients with low number ( / rf) of lnm risk factors after esd. aims: laparoscopic proximal gastrectomy has been applied for early gastric cancer in upper third. we previously reported outcomes of laparoscopic total gastrectomy in managing this condition. in this study, we applied this modified technique for upper third early gastric cancer with double tract reconstruction. it is expected that our technique could be useful for treating these cases. methods: from april of to june of , consecutive patients with upper third early gastric cancer were assigned to undergo surgical treatment with proximal gastrectory at our hospital. we had cases of total gastrectory for upper third early gastric cancer in the same study period. background: laparoscopic total gastrectomy for remnant gastric cancer is much more difficult than common laparoscopic total gastrectomy due to severe adhesions to adjacent organs, displacement of anatomical structure. purpose: the aim was to analyze cases of laparoscopic total gastrectomy for remnant gastric cancer at the department of surgery of juntendo university urayasu hospital between november and april . method: we analyzed outcome and feasibility of laparoscopic total gastrectomy surgery for remnant gastric cancer. and we compared with laparoscopic total remnant gastrectomy ( cases) versus laparoscopic total gastrectomy ( cases) in our hospital. results: in the previous laparoscopic surgeries. we performed laparoscopic distal gastrectomy in cases, laparoscopic proximal gastrectomy in pcases, and open distal gastrectomy in cases. all cases were performed laparoscopic total gastrectomy with r-y reconstruction. case of them had been converted to open surgery due to severe adhesions. the mean operative time was min and the mean blood loss was ml. there were no intraoperative complications, and there were postoperative complications as a pancreatic fistula and a bowel obstruction. however, there were no intra-operative complications more than grade according to the clavien-dindo classification. the mean postoperative hospital stay was . days. all cases were without recurrence. thus, there were no significant differences in operative time, bleeding volumes, intra and postoperative complications and hospital stay compared with laparoscopic total gastrectomy. conclusions: laparoscopic total remnant gastrectomy can be performed with similar short-term outcomes to laparoscopic total gastrectomy, and may be feasible and safe procedure, and can become an option of therapeutic strategy. although this study was not powered to show lower recurrence rates with synthetic absorbable as compared to biologic, the . % recurrence rate is consistent with other series utilizing this mesh. it is interesting to note the difference in time to recurrence. these results suggest that while synthetic absorbable mesh may result in lower recurrence rates, recurrence seems to occur earlier. the results also suggest that deconditioning (lower bmi), and difficult cases and/or recovery may predispose to recurrence. these findings can help inform lf mesh selection and predict which patients are at higher risk of recurrence. introduction: little discussion of gastroparesis (gp) following laparoscopic paraesophageal hernia repair (lphr) has been reported in the literature. we wished to examine the incidence in our institution, and identify potential risk factors for development of gastroparesis following lphr. methods and procedures: a single institution retrospective chart review was preformed using cpt codes corresponding to paraesophageal hernia repair and fundoplication to identify patients undergoing laparoscopic paraesophageal hernia repair over a five year period ( / / - / / ) by three surgeons. emergency procedures and reoperations were excluded. in total, patients undergoing non-emergent first time lphrs were identified. size of the hiatal defect was identified when able, via either measurement between the diaphragmatic crura on ct or by medical record documentation. data obtained included sex, age, hernia type, mesh usage, and existence of specific comorbidities associated with gastroparesis. presence of gastroparesis was identified either by documentation of diagnosis via clinical judgment, or by results of gastric emptying nuclear medicine studies, with timing being no longer than months from date of surgery. independent students t-test and fisher exact test were used to determine statistical differences between the groups. results: patients undergoing non-emergent first time lphrs were identified. of these, we were able to obtain the size of the hiatal defect in patients. patients overall were diagnosed with gastroparesis, with an overall incidence of . %. when comparing all patients who developed gastroparesis to those who did not, only females comprised the group which did develop gastroparesis ( males/ females with gp, males/ females without gp, p= . ). age was also found to be greater in the group which developed gastroparesis. for patients in which the size of the hernia defect was identified, the average age was years older in the group diagnosed with gastroparesis ( step under laparoscopic view, left part of the lesser omentum was cut with preserving the hepatic branch of vagus nerve. the right crus of the diaphragma has been dissected free from the soft tissue around the stomach and abdominal esophagus. in this step the fascia of the right crus should be preserved and the soft tissue should not been damaged to avoid bleeding. after cutting the peritoneum just inside the right crus, the soft tissue was dissected bluntly to left side. then the inside margin of the left crus of the diaphragma was recognized from the right side. in this part of the procedure, laparoscope uses trocar (a), the assistant uses trocar (b) to pull the stomach to left lower side and the operator's right hand uses trocar (c). step the branches of left gastroepiploic vessels and the short gastric vessels were divided with ultrasonic coagulation and dissection device. the left crus of the diaphragma was exposed and the window at the posterior side of the abdominal esophagus was widely opened. in this part of the procedure, laparoscope uses trocar (a) at the beginning of dividing left gastroepiploic vessels, trocar (b) when dividing short gastric vessels. step the right and left crus are sutured with interrupted stitches to reduce the hiatus. from the right side, the fundus of the stomach is grasped through the widely opened window behind the abdominal esophagus. then the fundus of the stomach is pulled to obtain a degree ''stomach-wrap'' around the abdominal esophagus (fundoplication). using - non-absorbable braided suture, stitches are placed between both gastric flaps. purpose: laparoscopic gastrecomy has been widely adopted as the treatment of choice by many countries and institutions. internal hernia is a well-known complication after rouxen-y gastric bypass in the field of bariatric surgery. however, there were only a few reports of internal hernia after gastrectomy in gastric cancer patients. the purpose of this study was to analyze the incidence and clinical features of internal hernia after gastric cancer surgery in a high-volume center. method: , gastric cancer patients who underwent curative gastrectomy at seoul national university bundang hospital between january and december were retrospectively reviewed in this study. internal hernia was classified into two types, mesenteric hernia and petersen's hernia. result: patients who underwent distal gastrectomy (dg) with reconstruction by billroth ii, rouxen-y gastrojejunostomy and uncut rouxen-y gastrojejunostomy, total gastrectomy (tg) with esophagojejunostomy, and proximal gastrectomy with double tract reconstruction (pg dtr) with esophagojejunostomy and gastrojejunostomy had potential space for internal hernia. among these patients, ( . %) were determined as internal hernia by computed tomography and patients ( . %) underwent surgical treatment of internal herniation. two patients were conservatively managed. all patients suffered from abdominal pain and / ( %) patients showed nausea and vomiting. the median interval between the initial gastrectomy and surgery for internal hernia was days. mesenteric hernia was observed in cases and petersen's hernia in cases. since we started closing the mesenteric and petersen's defects from may of , there were only cases ( %) observed afterwards but there were cases ( %) before closure of the defects. conclusion: internal hernia after gastrectomy is likely underreported. although we analyzed patients with internal hernia, there might be more patients with mild symptoms who were managed conservatively by their own. a high degree of suspiciousness for internal hernia should be maintained in patients presenting symptoms like nausea, vomiting and abdominal pain after gastrectomy with potential space for internal hernia. with our experience, closure of the mesenteric and petersen's defect is helpful in reducing internal hernia. however, due to low incidence, a multicenter retrospective study is necessary. introduction: the increased incidence of anemia in patients with a hiatal hernia (hh) has been clearly demonstrated, as has resolution of anemia after hh repair in these patients. despite this, the implications of preoperative anemia on postoperative outcomes have not been well described. in this study, we aimed to identify the incidence of preoperative anemia in patients undergoing hh repair at our institution and sought to determine whether preoperative anemia had an impact on postoperative outcomes. methods and procedures: using our irb-approved institutional hh database, we retrospectively identified patients undergoing hh repair between january and april at our institution. we identified all patients with anemia, defined as serum hemoglobin levels less than mg/dl in men and mg/dl in women, measured within two weeks prior to surgery, and compared this cohort to those that had normal hemoglobin values preoperatively. specific perioperative outcomes analyzed included: estimated blood loss (ebl), operative time, need for blood transfusion, failure to extubate postoperatively, intensive care unit (icu) admission, postoperative complications, length of stay (los), and -day readmission. results: we identified patients undergoing hh repair, of which had preoperative bloodwork available for review. the average age was years and the majority of patients were female ( %, n= ). most were treated electively ( %, n= ) and with a minimally invasive approach ( %, n= ). patients ( . %) had preoperative anemia. compared to patients without anemia, patients with anemia had increased rates of failed extubation postoperatively ( . % vs. . %, p= . ), increased icu admissions ( . % vs. . %, p= . ), increased need for perioperative blood transfusions ( . % vs %, p= . ), and increased rates of postoperative complications ( . % vs. . %, p. ). although mean los ( . days vs. . days, p . ), mean operating time ( mins vs. mins, p= . ), and ebl ( ml vs ml, p= . ) were greater in the anemic group, they did not reach statistical significance, and there was no significant difference in -day readmission rate ( . % vs . %, p= . ). conclusions: anemia diagnosed on preoperative bloodwork appears to be associated with increased failure to extubate postoperatively, need for icu admissions, need for perioperative blood transfusion, and increased overall complication rate after hh repair. however, we found no significant difference in los or -day readmissions between anemic and non-anemic patients. since the majority of patients in this analysis underwent elective repairs, these results would support the preoperative treatment of anemia in patients undergoing hh repair. few studies have compared the procedures' long-term effectiveness with none looking beyond years. this study sought to characterize the efficacy of laparoscopic toupet versus nissen fundoplication for types iii and iv hiatal hernia using a telephone survey. methods and procedures: with irb approval, a review of all laparoscopic hiatal hernia repairs with mesh reinforcement performed over seven years at a single center by one surgeon was conducted. patient demographics and perioperative characteristics were recorded. hiatal hernia was classified per published sages guidelines as type iii or iv using operative reports and preoperative imaging. patients with type i or ii or recurrent hiatal hernia and patients receiving concomitant procedures were excluded. the gerd-health related quality of life survey was administered by telephone no earlier than months postoperatively. patients responded to items concerning symptom severity using a -point scale ( =no symptoms to =symptoms are incapacitating to do daily activities). symptoms surveyed included heartburn ( items), difficulty swallowing ( item) and regurgitation ( items introduction: as the thoracic esophageal carcinoma has a high metastatic rate of upper mediastinal lymph nodes, especially along the recurrent laryngeal nerve (rln), it is crucial to perform complete lymph node dissection along the rln without complications. although intraoperative neural monitoring (ionm) during thyroid and parathyroid surgery has gained widespread acceptance as the useful tool of visual nerve identification, the utilization of ionm during esophageal surgery has not become common. here, we describe our procedures focusing on a lymphadenectomy along the rln utilizing the ionm. methods and procedures: we first dissect ventral and dorsal side of the esophagus preserving the membranous structure (meso-esophagus), which contains tracheoesophageal artery, rln and lymph nodes. we next identify the location of the rln which runs in the meso-esophagus using ionm before visual contact. after that, we perform lymphadenectomy around the rln preserving the nerve. this technique was evaluated in consecutive cases (neural monitoring group; nm) of esophagectomy in prone positioning, and compared with our historical cases (conventional method group; cm background: laparoscopic hiatal hernia repair, particularly large type and type hernias, is associated with high recurrence rates. various use of overlay mesh reinforcement have been described in an attempt to improve outcomes. unfortunately, overlay use of biologic mesh continues to result in high recurrence rates, and more effective repairs employing permanent mesh raise serious erosion concerns and are therefore rarely used. we theorize that employing an interlay technique with permanent mesh (positioned between both crura) will help enhance crural closure and improve rates of hiatal hernia recurrences with minimal risk of erosion. methods: we reviewed all patients who underwent a laparoscopic hiatal hernia repair from april to august by a single surgeon from a prospectively maintained database at a tertiary care referral center (n= ). patients who underwent surgery for achalasia with concurrent hiatal repair were excluded. during this time frame, a new interlay technique of polypropylene mesh was employed upon suture closure of the crura. outcomes of repair were retrospectively reviewed. recurrence of hernia was identified by positive work up of patient's symptoms (new onset dysphagia, gerd, pain). results: a total of consecutive laparoscopic hiatal hernia repair were reported in a period of months. interlay polypropylene mesh was utilized in all repairs. patients were majority females ( . %), had a median age of and had a mean bmi of . . eleven ( . %) patients were redo repairs. majority of patients received a nissen fundoplication (n= , . %) followed by a toupet fundoplication (n= , . %). median length of stay after surgery was day. median follow up was days (range: - days). there were zero reported recurrences. conclusion: laparoscopic hiatal hernia repair with interlay polypropylene mesh appears in the short term to be a safe and durable technique to reduce the incidence of hiatal hernia recurrences. further studies are needed to assess more long term outcomes of this novel technique. zia kanani , melissa helm , max schumm , jon c gould, md ; introduction: laparoscopic fundoplication remains the current gold standard surgical intervention for medically refractory gastroesophageal reflux disease. studies suggest that on average - % of patients undergo reoperative surgery due to recurrent, persistent, or new symptoms. the primary objective of this study was to characterize the long-term symptomatic outcomes of primary and reoperative fundoplications in a clinical series of patients who have undergone one or more fundoplications. methods: patients who underwent laparoscopic primary or reoperative fundoplication between and by a single surgeon were retrospectively identified using a prospectively maintained database. patients undergoing takedown of a failed fundoplication and conversion to roux-en y gastric bypass (for morbid obesity, severe gastroparesis, or or more prior failed attempts) were excluded from the current analysis. all procedures were performed laparoscopically. patients were asked to complete the validated gerd-health related quality of life (gerd-hrql) survey prior to surgery and postoperatively at standard intervals to assess long-term symptomatic outcomes and quality of life. gerd-hrql composite scores range from (highest disease-related quality of life) to (lowest diseaserelated quality of life, most severe symptoms conclusions: patients who need to undergo reoperative fundoplication have more severe gerd-related symptoms at years post-op compared to patients undergoing primary fundoplication. however, good outcomes and morbidity rates of laparoscopic reoperation that approximate that of a primary fundoplication are possible in the hands of an experienced surgeon. adenocarcinoma of duodenum: surgical or endoscopic treatment? introduction: it is well known that the adenocarcinoma of the duodenum (adc) is a quite rare lesion infact represents % of cancer of the small bowel and % of these are localized in the periampullary area: % affect the sub-papillary tract and only % the supra-papillary segment of the duodenum. the adc may arise from duodenal polyps (familial polyposis, or gardner's syndrom or be associated with coeliac disease). until now the treatment was the pancreatoduodenectomy (for anatomo-surgical reasons and for the possibility of regional lymphonode resection). infact in my series of of such procedures, where performed for duodenal cancer. in this last years patients with adc of supra-papillary segment of the duodenum underwent endoscopic submucosal dissection (esd). the purpose of this study were to check the feasibility of the esd in treating such cases. in our experience this kind of endoscopic operation was feasible with high complication rate; perforation in cases ( . %); and bleeding occurred in case ( . %). all the complications were successfully treated endoscopically and the long-term outcomes was favorable. consitering the high rate of complications, the difficult and long procedure, the compliance of patients (c ), the general anesthesia, a very very skilled endoscopist is needed. conclusions: the esd represent a new endoscopic approach enstablished in clinical practice: end is performed following the intraluminal path ( rd space) wich, unlike the others, remain virtual and has to be created by dissecting and expanding the tissues layer between the mucosa and the muscolaris propria allowing the endoscope to gain access. the benefit of esd for treating the adc of the supra-papillary segment of the duodenum, according to our experience, must be validate in the future; a pre-operative pet-tac scan examination must be performed in order to demostred the lesion of the duodenum and if there is any limphatic involvement and no infiltration of the head of the pancreas. yoontaek lee, md, sa-hong min, md, young suk park, md, sang-hoon ahn, md, do joong park, md, phd; seoul national university bundang hospital purpose: this study summarizes the single institution experience of laparoscopic gastrectomy in advanced gastric cancer and evaluates the postoperative morbidities and long-term oncologic outcomes. methods: a total of , laparoscopic gastrectomy for advanced gastric cancer were performed at seoul national university bundang hospital between may and may . the characteristics of patients, surgical techniques, postoperative morbidities, and long-term oncologic outcomes were retrospectively reviewed using electronic medical records. results: patients required conversion to open surgery. the reasons of conversion to open surgery were advanced stage (n= ), intraoperative bleeding (n= ), adhesion due to previous abdominal operation (n= ), small abdominal cavity (n= ), associated disease (n= ), and intraoperative pleural injury (n= ). the mean hospital stay was . days for distal gastrectomy, . days for total gastrectomy, . days for proximal gastrectomy, and . days for pylorus preserving gastrectomy. the mean number of collected lymph nodes was . for distal gastrectomy, . for total gastrectomy, . for proximal gastrectomy, and . for pylorus preserving gastrectomy. the rates of postoperative complications of grade ii or more were . %. there was one case of postoperative mortality due to delayed bleeding after discharge. old age was the only independent predictor of surgical morbidities. background: intrathoracic gastric volvulus is a life-threatening condition of paraesophageal hernia. the therapeutic is a challenge because in acute volvulus it may lead to gastric strangulation and necrosis. most patients are elderly and with a significant associated medical illness which has higher morbidity and mortality of major surgery. we present a laparoscopic surgery is safe in paraesophageal hernia with acute intrathoracic gastric volvulus in a high-risk patient. case presentation: an -year-old woman with underlying of diabetes mellitus and hypertension was transferred from an outlying hospital with anemia, dysphagia, urinary tract infection and aspiration pneumonia. she had severe recurrent emesis after admission. ct scan of the chest and abdomen revealed a large esophageal hiatal hernia, and most of the stomach was in the inferior mediastinum with organoaxial gastric volvulus. endoscopy revealed flat pigmented spot gastric ulcer which compatible with cameron lesion and twisting of gastric folds without evidence of ischemia. the endoscopic reduction was unsuccessful. a laparoscopic surgery was performed and the herniated stomach was successfully reduced. the hernial sac was excised. the crura were approximated and reinforced with composite mesh. nissen fundoplication was performed along with gastropexy of the greater curve of the stomach to the abdominal wall. there was no perioperative complication. she tolerated enteral diet on a postoperative day . she had an uneventful recovery and discharged in weeks after treatment of her associated medical illnesses. she had no relapse of previous symptoms at her six-month follow-up assessment. discussion: endoscopic reduction of acute gastric volvulus may be the first option in a patient with severe comorbidities. however, if there is evidence of ischemia or failure of endoscopic reduction, surgical treatment should be considered. laparoscopic reduction and gastropexy may be a lessinvasive and viable alternative to the more aggressive surgical procedure but definitive surgery with repair hiatal hernia can be done in a selected patient. conclusion: minimally invasive treatments of acute gastric volvulus with paraesophageal hernia, either endoscopic or laparoscopic offer the option for reducing morbidity and mortality in elderly with significant comorbidities. the definitive laparoscopic surgery can be accomplished successfully and safely when it is performed with meticulous attention to the surgical technique and perioperative care. reid fletcher, md, mph, emily ramirez, rn, alfonso torquati, md, philip omotosho, md; rush university medical center introduction: the objective of this study was to evaluate the impact of an enhanced recovery after surgery (eras) program on post-operative length of stay following laparoscopic sleeve gastrectomy. eras programs have been demonstrated to improve outcomes and decrease length of stay in multiple surgical disciplines however relatively little has been published regarding the impact of eras programs in bariatric surgery. methods: an eras program for all patients undergoing bariatric surgery was implemented in february at a single institution. we retrospectively reviewed all patients undergoing laparoscopic sleeve gastrectomy between february and august . as a pre-eras historical control, we also reviewed all patients undergoing laparoscopic sleeve gastrectomy between january and december . baseline patient characteristics, additional concomitant operative procedures as well as -day readmission and complication rates were reviewed. logistic regression analysis was used in univariate and multivariate models to identify factors that predicted early post-operative discharge. data analysis was completed using stata se software (statacorp lp; college station, tx). results: eighty-five patients underwent laparoscopic sleeve gastrectomy after implementation of the eras program while patients were included in the pre-eras control group. there were no statistically significant differences in the baseline characteristics between the two groups and there were no differences in the rate of concomitant procedures performed. there was a statistically significant decrease in post-operative length of stay following implementation of the eras program from . it has been reported that laparoscopic redo surgery is effective for recurrent gerd and/or hiatal hernia after surgery. however, there has been very few reports from japan. we report an initial experience of laparoscopic surgery for japanese patients with recurrent gerd and/or hiatal hernia. among patients who had undergone laparoscopic fundoplication in our hospital from to , patients with recurrent gerd/hiatal hernia underwent redo surgery. preoperative work-up included upper gi series, endoscopy, ct, h ph-impedance and manometry. the patients consisted of women and men with a mean age of . years. the interval from the initial surgery was . months ( days- months). the types of initial fundoplication were nissen: , toupet: , anterior: . the types of recurrence were sliding hernia: and paraesophageal hernia: . one patient with recurrent sliding hernia had poor gastric motility. laparoscopic redo surgery was performed on patients. redo surgery included crural repair with mesh reinforcement: , refundoplication: (nissen-nissen: , nissen-toupet: , toupet-toupet: , toupet-lateral: ) and reduction of the incarcerated paraesophageal hernia: . additional procedure included mesh reinforcement: and pyloroplasty: . open partial gastrectomy was performed for one patient with incarcerated and strangulated hernia. operation time was min. patients was converted to open surgery. oral intake was started on the st pod and postoperative stay was . days. two patients recurred after redo surgery, one of whom underwent re-redo surgery. during the surgery, ivc was injured but rescued by open surgery. eleven patients had good outcome and patients required ppi after redo surgery. our morphological fundoplication score significantly improved after redo surgery. symptom score and acid exposure time were also significantly improved after redo surgery. laparoscopic redo surgery for recurrent gerd and/or hiatal hernia after surgery is safe and effective, although attention should be paid during surgery to avoid injury of the adjacent organs. surg endosc ( ) introduction: cameron ulcers (cu) are linear erosions or ulcerations in the gastric mucosa at the level of the diaphragmatic hiatus in patients with a hiatal hernia (hh) and are frequently associated with anemia. perioperative outcomes of patients with cu undergoing hh repair are not well described. we sought to identify the incidence of cu in patients undergoing hh repair at our institution and determine whether the presence of cu impacted postoperative outcomes. methods and procedures: using our irb-approved institutional hh database, we retrospectively identified patients undergoing repair between january and april . we identified all patients with cu found on preoperative esophagogastroduodenoscopy (egd). we compared patients with and without cu to determine if they differed in terms of preoperative anemia (defined as hemoglobin levels less than mg/dl in men and mg/dl in women). lastly, we compared outcomes between the cu group and the non-cu group, focusing on need for perioperative blood transfusion, failure to extubate postoperatively, intensive care unit (icu) admission, postoperative complications, length of stay (los), and -day readmission. conclusions: the presence of cu on preoperative egd is associated with increased rate of preoperative anemia, increased los, and increased icu admission after hh repair. although the cause of anemia in patients with hh is commonly attributed to cu, only % of cu patients were anemic, indicating that differences in outcomes may not only be attributed to a higher incidence of anemia in cu patients. the implications of cu in patients undergoing hh repair need to be further elucidated. laparoscopic heller myotomy as treatment for achalasia objective: aim of this stud was to review our experience with laparoscopic heller dor myotomy. disphagia constitutes the main symptom. diagnosis is performed by means of esophageal manometry. materials and method: over a period of years, patients were treated with heller myotomy plus dor fundoplication laparoscopically. all patients had lost weight, and there was a prevalence of females with an average age of . twenty five patients had chagas disease. they were all assessed with serial x-rays, endoscopy, esophageal manometry, and their symptoms were assessed with a - score, being the most severe. results: there was no conversion or mortality. in patients the mucosa was perforated during myotomy. the mucosa was sutured without altering the result of the treatment. average hospital stay was hours. one patient had to be reoperate because of esophageal perforation with peritonitis. sixty patients were followed up with manometric control and ph-probe testing, and only % of those had pathologic reflux. conclusions: laparoscopic treatment of achalasia is possible and reproducible, while reducing the morbility of laparotomy with relieve of patients symptoms. introduction: stent treatment in the gastrointestinal tract is emerging as a standard therapy for overcoming strictures and sealing perforations. we have started to treat patients with perforated duodenal ulcers using a partially covered stent and external drainage achieving good clinical results. stent migration is a serious complication that may require surgery. pyloric physiology during stent-treatment has not been studied and mechanisms for migration are unknown. the aims of this study were to investigate the pyloric response to distention mimicking stent-treatment, using the endoflip, investigating changes in motility patterns due to distention at baseline, after a pro-kinetic drug and after food ingestion. methods: a non-survival study in five pigs was carried out, followed by a pilot study in one human volunteer. a gastroscopy was performed in anaesthetized pigs and the endoflip was placed through the scope straddling the pylorus. baseline distensibility readings were performed at stepwise balloon distention to ml, ml, ml and ml, measuring pyloric cross sectional area and pyloric pressure. measurements were repeated after administration of a pro-kinetic drug (neostigmin) and after instillation of a liquid meal. in the human study readings were performed in conscious sedation at baseline and after stimulation with metoclopramide. results: during baseline readings the pylorus was shown to open more with increasing distention, together with higher amplitude motility waves. reaching maximum distention-volume ( ml), pyloric pressure increased significantly (p= . ) and motility waves disappeared. after prokinetic stimulation pyloric pressure decreased and motility waves increased in frequency and amplitude at , and ml distentions. after food stimulation pyloric pressure stayed low and motility waves showed increase in amplitude at distentions of , and ml. during both tests the pylorus showed higher pressure and lack of motility waves at maximum probe distention of ml. similar results were found in the human study. the pylorus seems to acts as a sphincter at low distention but when further dilated starts acting as a peristaltic pump. when fully distended, pyloric motility waves almost disappeared and the pressure remained high, leaving the pylorus open and inactive. stent placement in the pylorus results in pyloric distention, possibly changing motility. this study indicates that a duodenal stent placed over the pylorus should have a high radial force in the pyloric part in order to dilate the pylorus and diminish the contraction waves, this might reduce stent migration. introduction: cutting-edge technology in the field of minimal invasive surgery allows the application of singleincision laparoscopic surgery on gastric cancer. however, single-incision distal gastrectomy (sidg) is still technically difficult due to limited range of motion and unstable field of view-even in the hands of an experienced scopist. solo surgery using a passive scope holder may be the key in allowing sidg to be safer and efficient. we report our initial experience of consecutive cases of solo sidg. methods: prospectively collected database of patients clinically diagnosed as early gastric cancer who underwent solo sidg from october until july were analyzed. all the operations were held by a single surgeon and a scrub nurse. a passive laparoscopic scope holder was controlled by the surgeon to fix the field of view. results: the mean operation time (sd) was . (± . ) min, and the average estimated blood loss was . ± . ml. average body mass index was . ± . kg/m . the median hospital stay (range) was ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) days, and the mean number of retrieved lymph nodes was . ± . . there was no conversion to multiport or open surgery. early postoperative complication occurred on % with three delayed gastric emptying, two postoperative pneumonia, one pancreatitis, and one wound complication. conclusion: solo sidg using a passive scope holder allows sidg to become more feasible by providing a stable field of view. there were no peri-operative deaths in either group. in the elective group, age was not an independent risk factor for complications (or . , % ci . - . ). conclusions: the incidence of major complications and mortality in this series were much lower than those previously reported for elective lpehr, while morbidity after emergency repair remains high. the paradigm of watchful waiting for elderly and/or minimally symptomatic patients with giant peh should be revisited. the impact of vagal nerve integrity testing in the surgical kamthorn yolsuriyanwong, md, eric marcotte, md, mukund venu, bipan chand, md; loyola university chicago, stritch school of medicine background: thoracic and gastric operations can cause vagal nerve injury, either accidentally or intended. the most common procedure, which can lead to such an injury, includes fundoplication, lung or heart transplantation and esophageal or gastric surgery. patients may present with minimal symptoms or some degree of gastroparesis. gastroparetic symptoms of include nausea, vomiting, early satiety, bloating and abdominal pain. if these symptoms occur and persist, the clinician should have a high suspicion of a possible vagal injury. investigative studies include endoscopy, esophageal motility, contrast imaging and often nuclear medicine gastric emptying studies (ges). however, ges in the post-surgical patient have limited sensitivity and specificity. if a vagal nerve injury is encountered, subsequent secondary operations must be planned accordingly. methods: from january to august , patients who had a previous surgical history of a foregut operation, with the potential risk of a vagal nerve injury, had vagal nerve integrity (vni) test results reviewed. vni test was measured indirectly by the response of plasma pancreatic polypeptide to sham feeding. the data collected and analyzed included age, gender, previous surgical procedures, clinical presentation, results of vni testing and the secondary procedure planned or performed. vni testing was compared to other testing modalities to determine if outcomes would have changed. results: eight patients ( females) were included. the age ranged from to years. two patients had prior lung transplantation and six patients had prior hiatal hernia repair with fundoplication. seven patients presented with reflux and delayed gastric emptying symptoms. one lung transplantation patient had no symptoms but his lung biopsy pathology showed chronic micro-aspiration with rejection. the vni testing results were compatible with vagal nerve injury in patients. according to these abnormal results, the plans for nissen fundoplication in patients were modified by an additional pyloroplasty and the plans for redo-nissen fundoplication in patients were changed to redo-nissen fundoplication plus pyloroplasty in patient and partial gastrectomy with roux-en-y reconstruction in patients. the operative plans in patients with a normal vni test were not altered. all patients that had secondary surgery had improvement in symptoms and or improvement in objective tests (ie signs of rejection). conclusion: the addition of vni testing in patients with previous potential risks of vagal nerve injury may help the surgeon select the appropriate secondary procedure. . we present a single-center experience with a "myotomy first" approach for all patients, regardless of diverticular size. the hypothesis is that cardiomyotomy alone will provide satisfactory symptom abatement in some patients. and mis cardiomyotomy causes minimal scarring, so a staged mis diverticulectomy is feasible at a later date if diverticular retention/stasis continues. in order to discuss this treatment algorithm we present our experience with cardiomyotomy alone for patients with epiphrenic diverticula. methods: the electronic medical record was queried for patients with esophageal diverticula who were managed with cardiomyotomy and dor fundoplication alone. pre and post-operative reflux/dysphagia questionnaires were gathered; imaging studies, operative data, complications and follow up were reviewed. results: from march of until the present, patients with esophageal diverticula were treated using the "myotomy first" approach. intraoperative esophagoscopy was done to internally visualize the elimination of the inciting spastic esophageal muscle. preoperatively, all patients complained of regurgitation, followed by dysphagia in ( %) and weight loss ( %). postoperatively, dysphagia and weight loss resolved in all subjects. regurgitation symptoms resolved in ( %) patients. the average size of the diverticula was . cm , the range was - cm . post operative esophagream's showed persistent diverticual, however most had decreased in size. there were no perioperative complications, average length of stay was . days and there were no icu admissions or returns to the or. the average length of follow up for these patients was days where all patients reported being satisfied with their results and none of them have yet desired to pursue diverticulectomy. discussion: a "myotomy first" approach resulted in excellent short term symptomatic control. none of the have retained or re-experienced symptoms of diverticular retention worthy of surgical intervention. in the age of laparoscopic surgery, an esophageal epiphrenic diverteculectomy should be staged. this step wise approach seeks to assure surgical necessity for a morbid endeavor. surg endosc ( ) :s -s the background: the two-stage oesophagectomy (ivor-lewis procedure) remains the mainstay of curative surgery for oesophageal cancers in the uk. gastro-oesophageal anastomotic leak is a potentially devastating complication of this procedure affecting perioperative morbidity and mortality. although the leak rates have improved over the years, it still remains widely variable. intraoperative reinforcement of gastro-oesophageal anastomosis with an 'omental wrap' has been proposed as a measure to reduce anastomotic leak rates. there is some data to suggest that this additional technique reduces anastomotic leak. we reviewed our single institution data to assess if the omental wrap indeed had a 'cocoon' effect in maturing the anastomosis and reducing leak rates. methods: data for all cancer oesophagectomies (ilog) performed in our institute since april - was retrospectively analysed from a prospectively maintained database. the patients were categorised into two groups. masafumi ohira; department of gastroenterological surgery, hokkaido university graduate school of medicine background: in laparoscopic surgery, both surgical technique and adequate support and traction by an assistant are highly important. this study assessed the impact of the first assistant on shortterm outcomes of laparoscopic distal gastrectomy (ldg) and laparoscope-assisted distal gastrectomy (ladg). methods: patients who underwent ldg or ladg for gastric cancer at our hospital, between november and august , were included. ldg and ladg cases of billroth i reconstruction, performed by a single surgeon accredited in endoscopic procedures, were analyzed. the cases were categorized into the following groups according to the first assistant's postgraduate years (pgy) of experience: group a, - years; group b, - years; group c, - years; and group d, [ years. short-term outcomes were compared between the groups. results: we examined cases. operative time was significantly longer in group a than in group b (p= . ). no significant differences in operative time were found between groups b, c, and d. the cases were recategorized into groups as follows: group a, the young assistant group (group y, n= ), and groups b, c, and d, the senior assistant group (group s, n= ). significant differences in operative time and method of anastomosis (circular stapler or delta anastomosis) were observed between the groups (p= . and p= . , respectively), but no significant differences in complication rates were found (p= . ). the unadjusted analysis revealed that the group, method of anastomosis, and body mass index (bmi) were significant factors associated with longer operative time. multivariate linear regression analysis with stepwise model selection using akaike's information criterion (aic) revealed that bmi and group were significant factors associated with longer operative time (p= . and p= . , respectively). multivariate analysis using these variables and the method of anastomosis confirmed the significance of bmi and group for longer operative time, but no significance was found in the method of anastomosis (p= . , p= . , and p= . , respectively). conclusions: our study showed that operative time tended to be longer when the first assistant had experience of less than pgy, but the morbidity did not increase. as with the operator, the first assistant needs adequate training to ensure a smooth operation. steven g leeds, md, marc ward, md, brittany buckmaster, pa, estrellita ontiveros, ms; baylor university medical center at dallas background: gastric contents can reach beyond the esophagus into the larynx and pharynx causing an increasingly prevalent disease called laryngopharyngeal reflux (lpr). magnetic sphincter augmentation (msa) has been used as an alternative treatment for gerd with good success, but there is no data to support its use in lpr. methods: forty-five patients with msa implants for symptomatic relief with both gerd and lpr symptoms were examined. all patients experienced at least one typical gerd symptom as well as at least one extra-esophageal symptom. this was assessed using the gerd-hrql which is questions graded - on each question, and reflux symptom index (rsi) which is questions graded - on each question. patients filled out questionnaires preoperatively, one month postoperatively (early follow up), and at months to year postoperatively (late follow up). the responses on the gerd-hrql were clustered into questions inquiring about heartburn ( ), dysphagia ( ), and regurgitation ( ) like all surgical fields there is a push towards standardization of the post operative course while maintaining safe practices. other surgical fields have streamlined recovery processes in an effort to standardize care and minimize costs. laparoscopic hiatal hernia repair is a complex procedure, but with experience and a team approach, this operation can become a streamline process. methods: a retrospective review was done for over laparoscopic hiatal hernia repairs at a single institution. aspects of post operative care such hospital floor, nursing ratio utilized, pain medication, diet advancement, use of foley catheters and length of hospital stay were tracked. statistical analysis was done to compare utilization of resources as years went on along with complications and readmissions. results: a total of hiatal hernias were performed between and . improvements were noted in nearly every field over time, including faster foley removal, decreased length of hospital stay, decreased use of patient controlled analgesics (pcas) and faster advancement of diet. furthermore these patients are now treated on a surgical floor rather than the intensive care unit or step down with a higher nurse to patient ratio, decreasing hospital cost. there were no changes in complications, reoperations or readmissions over the course of the study. conclusions: cost, length of stay and so called "advanced recovery pathways" are all the rage in the surgical literature. anytime a procedure and its post operative course can become less of a "major undertaking" and more routine, the more streamline it becomes. this comes from making a standard protocol that deescalates treatment based on what is actually needed. nearly every aspect of post operative care was simplified; length of stay and cost to the hospital was decreased while no additional complications or readmissions were accrued. the foundation of a formalized advanced recovery pathway will be implemented from these factors which were studied. background: the obesity epidemic continues to worsen. bariatric surgery remains the most effective way to achieve weight loss and resolution of comorbidities. laparoscopic sleeve gastrectomy has become the most common bariatric operation due to excellent efficacy and low morbidity and mortality. the most common complication of sleeve gastrectomy is gastroesophageal reflux disease (gerd), which can adversely impact the quality of life and lead to additional esophageal complications. recently, esophageal magnetic sphincter augmentation (linx®) has become an acceptable alternative to fundoplication for certain patients with gerd. the use of linx® in patients who previously underwent laparoscopic sleeve gastrectomy was described in a case series in . the known complications of these devices include dysphagia, need for endoscopic dilation, and device erosion. the complication profile of linx® in the setting of sleeve gastrectomy has not been reported heretofore. methods: we present a case of a patient with prior sleeve gastrectomy who received a linx® device one year after her bariatric operation due to severe gerd refractory to medical management. initial evaluation demonstrated a hypotensive lower esophageal sphincter and hiatal hernia, but no evidence of stricture or twisting. soon after linx® implantation, the patient developed progressive dysphagia and worsened reflux. repeat evaluation showed esophagitis, a moderate stricture with angulation at the incisura, and a large amount of retained food. discussion: the patient was recommended conversion to roux-en-y gastric bypass, but was deemed to be a poor candidate due to heavy smoking. thus, laparoscopic removal of the linx® device was performed with hiatal hernia repair and gastric stricturoplasty. post-operative fluoroscopic evaluation revealed improvement in the stricture, but persistent gastroesophageal reflux. the patient experienced a significant improvement in her symptoms of dysphagia, nausea, and vomiting. however, once smoking cessation is achieved, she may still need a conversion to roux-en-y gastric bypass in order to address persistent gerd. conclusion: conversion to roux-en-y gastric bypass remains the standard approach to treatment of gerd post sleeve gastrectomy. new approaches to this problem, including placement of linx®, are promising but have not been evaluated for long-term safety and efficacy in the setting of prior bariatric surgery. careful diagnostic evaluation prior to placement of magnetic sphincter augmentation device should be routinely undertaken. postoperatively, close long-term follow up is imperative, particularly in patients with prior sleeve gastrectomy. presence of linx® in a patient with prior bariatric surgery may lead to worsening symptoms if complications of initial operation are present. kazuto tsuboi, md , nobuo omura, md , fumiaki yano, md , masato hoshino, md , se-ryung yamamoto , shunsuke akimoto, md , takahiro masuda , hideyuki kashiwagi, md , norio mitsumori, md , katsuhiko yanaga, md ; fuji city general hospital, shizuoka, japan, nishisaitama-chuo national hospital, saitama, japan, the jikei university school of medicine, tokyo, japan background: esophageal achalasia is one of the primary esophageal motility disorders, and the patients suffer from dysphagia, vomiting and chest pain. timed barium esophagogram (tbe) is a convenient method to assess esophageal clearance, which we usually performed before and after surgery. meanwhile, laparoscopic heller-dor operation (lhd) has been considered worldwide as a gold standard for the surgical management of esophageal achalasia. the aim of this study is to examine the effect of preoperative clearance rate at the lower part of the esophagus on surgical outcomes in patients with esophageal achalasia. patients and method: between august and april , patients who underwent lhd at our institution were extracted from the database. out of patients, patients met our inclusion criteria; such as the patients who underwent lhd as an initial operation with complete evaluation with preoperative esophageal clearance by tbe. these patients were divided into three groups by the degree of esophageal clearance (group a: clearance rate \ %, group b: %? clearance rate \ %, and group c: %? clearance rate). patients' background, pre-and post-operative symptom scores, and surgical results were compared. before and after surgery, the standardized questionnaire was used to assess the degree of frequency and severity of symptoms (dysphagia, vomiting, chest pain and heartburn). moreover, satisfaction with operation was evaluated using the standardized questionnaire. statistical analysis was performed by using krasukal-wallis test or chi-square test, and p-value less than . was defined as statistically different. results: their mean age was . years and of them were male ( . %). one hundred and sixty-eight patients ( . %) were in group a, ( . %) in group b, and ( . %) in group c. the maximum width of the esophagus in group c was smaller than that in other groups (p= . ). as to the pre-operative symptom score, the frequency score of dysphagia was significantly lower in group c (p= . ), whereas the severity score of chest pain was significantly higher in group c (p= . ). surgical outcomes including the incidence of mucosal injury were not different among the groups. moreover, the patient satisfaction with lhd was excellent regardless of preoperative esophageal clearance. conclusion: preoperative clearance rate at the lower part of the esophagus in patients with esophageal achalasia did not affect the surgical outcomes of lhd, but the characteristics of preoperative symptoms in patients with poor esophageal clearance was low dysphagia and high chest pain. surg endosc ( ) ( . cm . cm) was made by dissecting between submucosal and muscular layers at the anterior remnant gastric wall. after creation of the double flap, the posterior esophageal wall ( cm from the edge) and the anterior gastric wall (superior edge of the mucosal window) were sutured for fixation, and . cm from the inferior edge of the mucosal window was opened, and the wall of the esophageal edge and the opening of the remnant gastric mucosa were sutured continuously. the anastomosis was fully covered by the seromuscular flaps with suturing. in latg, roux-en-y reconstruction was performed through a small incision using a circular stapler. introduction: the purpose of this study was to clarify the long-term and short-term outcomes of consecutive patients who underwent thoracoscopic esophagectomy in the prone position using a preceding anterior approach for the resection of esophageal cancer at a single institution. this method was established to make an esophagectomy easier to perform and to achieve better outcomes in terms of safety and curativity. methods and procedures: we retrospectively reviewed a database of patients with thoracic esophageal cancer who had undergone a thoracoscopic esophagectomy (te, patients) or an esophagectomy through thoracotomy (oe, patients) between january and august . to compare the long-term outcomes of te and oe, we used a propensity score matching analysis and a kaplan-meier survival analysis. to analyze the short-term outcomes of te, patients were chronologically divided into three groups: a first period group ( patients), a second period group ( patients), and a third period group ( patients). as for thoracoscopic procedure, the esophagus was mobilized from the anterior structure during the first step and from the posterior structure during the second step. the lymph nodes around the esophagus were also dissected anteriorly and posteriorly. the intraoperative factors, the number of dissected lymph nodes, and the incidence of adverse events were compared among the three period groups using a one-way anova or chi-square test. results: one hundred and twenty-three patients from each group, for a total of patients, were completely selected and paired. background: it is also difficult to anastomose using circular stapler in the narrow neck field. to overcome the problem we modified circular stapling for anastomosis. gastric juice reflux is frequently observed at the esophagogastric anastomosis. we develop and report trapezoidal tunnel method to reduce the incidence reflux. ( ) patients one hundred thirteen cases ( in left lateral and in prone position), with esophageal carcinomas underwent vats-e, respectively. esophago-gastric anastomosis is performed for cases by modified circular stapling and cases by trapezoidal tunnel method. ( ) methods at first the patients are fixed at semi-prone position and esophagectomy is performed in prone position that can be set by rotating and ports are used at the intercostal space (ics). esophagectomy and the l.n. dissection are performed with pneumothorax by maintaining co insufflation. esophago-gastric anastomosis is performed as following, i) trapezoidal tunnel method sero-muscular layer of anterior wall in the near top of gastric conduit is peeled from submucosal layer after parallel horizontal incision of sero-muscular layer, and then trapezoidal tunnel of sero-muscular layer is created. the edge of the proximal esophagus is drawn into the tunnel and esophago-gastric submucosa anastomosis is performed. to wrap anastomosis distal side of parallel line is closed. ii) modified circular stapling at first the circular stapler is introduced into the gastric conduit and joined to an anvil, and close a little. and then a joined anvil is placed into the proximal esophagus and secured by means of a pursestring suture. the gastric conduit opening is closed by a linear stapler. purpose: mesh utilization and its impact on postoperative hernia recurrence following paraesophageal hernia repair remains a polarizing topic. this analysis evaluates the recent trends in laparoscopic paraesophageal hernia repairs and analyzes the impact of operative time on postoperative morbidity. methods: the - acs-nsqip database was queried for primary cpt code for laparoscopic paraesophageal hernia repair with and without mesh ( / ). only elective cases performed by a general surgeon were included. operative time was grouped into quartiles ( - , - , - , - min) and statistical analysis was performed using anova univariate with post-hoc testing and multivariate regression modeling controlling for age, diabetes, renal disease and weight loss. this analysis was powered to detect a greater than % difference in outcomes based on mesh utilization. the outcomes of interest were composite morbidity scores and readmission rates within days of surgery. results: the database identified a cohort of , laparoscopic paraesophageal hernia repairs performed between and . average patient age was years and average patient body mass index was . mesh was utilized in % of cases per year and did not change over the study period (p= . ) however mesh utilization was %, %, %, and % within operative time quartiles - respectively (p. ). postoperative morbidity and readmission rates for each operative time quartile were . %, . %, . %, and . % (p. ) and . %, %, . %, and . % (p= . ), respectively. post-hoc testing indicated statistically significant differences in postoperative morbidity and readmission rates between quartiles and / . multivariate regression analysis documented operative time as a risk factor for postoperative morbidities and readmission, even after controlling for covariates. mesh utilization was only significant for a reduction in the rate of venous thromboembolic complications (or . , p= . ) but did not impact other morbidities or readmission rates. conclusion: this analysis suggests that patients with higher operative times have increased postoperative morbidity and readmission while mesh utilization does not impact postoperative outcomes, after accounting for the longer operative time of a paraesophageal hernia repair with mesh. introduction: gastroparesis is a chronic gastric motility disorder defined by delayed gastric emptying and symptoms such as nausea, vomiting, bloating and abdominal pain. surgical options for refractory gastroparesis include pyloroplasty, gastric stimulator insertion, and gastrectomy. the palliation from a pyloroplasty and gastric stimulator may be synergistic, however concerns remain regarding the possibility of stimulator infection when performing both procedures simultaneously. we present our initial experience of combined laparoscopic pyloroplasty and insertion of gastric stimulator. methods: gastroparesis patients diagnosed by solid gastric scintigraphy or endoscopic evidence of retained food after prolonged npo status who underwent combined laparoscopic heineke-mikulicz pyloroplasty and gastric stimulator insertion between july and july were reviewed. patient demographics, pre-and post-operative symptom scores and outcomes were collected. results were analyzed using statistical tests as appropriate. p value . were considered significant. results: seven patients underwent the simultaneous pyloroplasty and gastric stimulator insertion. six patients ( %) were idiopathic and one patient ( %) was diabetic. one patient was male and six patients were female. charleen yeo, enming yong, danson yeo, kaushal sanghvi, aaryan koura, jaideepraj rao, myint oo aung; tan tock seng hospital introduction: gastric cancer is one of the most common cancers in the asian population, with recent literature supporting the laparoscopic approach in early disease. however, the minimally invasive approach in advanced disease is still controversial. the outcomes of laparoscopic gastrectomy in the elderly have also not been extensively studied. we aim to evaluate our institution's short term outcomes of laparoscopic versus open gastrectomy for gastric cancer-with particular focus on advanced disease and elderly patients. methodology: we prospectively collected the data of all patients who underwent gastrectomies for stomach cancer from to . all patients underwent a partial or total gastrectomy with d lymphadenectomy. the decision for open or laparoscopic approach was decided between surgeon and patient. we excluded patients who underwent palliative resection. all patients were followed up for at least one year post-operatively. introduction: it was an eye-opener when the lancet brought the attention about global surgery. it is estimated that the deaths due to lack of access to surgery is far greater than deaths due to malaria, tuberculosis and hiv/aids put together. there is greater need to stress the importance in developing countries. there is a responsibility at the medical schools to enlighten students about this necessity and arouse interest in concept of global surgery. the students or surgical residents in the future are a great resource to solve this major problem. the first step would be to educate surgical residents. we need to assess the existing awareness about global surgery problem among surgical residents. we can plan a program to train the next generation surgeons. methods and procedure: all the surgical residents in our institution (victoria hospital, bangalore, india) were enrolled for this study. a total of residents were enrolled. a multiple-choice questionnaire regarding global surgery was designed. the received questionnaire was analyzed to assess the depth of knowledge about global surgery. there were multiple choice questions (mcq) and an option was provided at the end for feedback and suggestion to improve the global surgery in our country. each question carried one mark. score more than was considered the cutoff for pass and those students were termed 'informed'. results: ( . %) students cleared the cut off score of and were termed 'informed'. among this group ( %) residents scored marks. ( . %) students did not cross the cut off and were termed 'non-informed'. among these ( . %) students scored marks and did not know anything on the topic. students provided relevant suggestions and opinions to improve global surgery issue. conclusion: there is a great lacuna in knowledge about global surgery among surgical residents. we need to plan a program integrating global surgery in the syllabus of surgical training. the awareness among residents would arouse interest and participation in the future. introduction: minimally invasive surgical techniques (mists) could have tremendous applications and benefits in resource poor environment. these include but are not limited to short hospital stay, reduced cost of care, and reduced morbidity, especially related to post operative infections. there is growing interest in mists in most low and middle income countries (lmic) but its adoption has remained limited largely due to high cost of initial set-up, lack of technological backup and limited access to training among others. one of the most limiting factors is the maintenance of the vision system. an affordable laparoscopic set-up as an example will therefore go a long way in improving access to mists. methods and procedures: a common zero-degrees mm scope is attached on the camera of a low price smartphone (samsung galaxy j , samsung®, seoul, south korea). two elastic bands are used to fix the scope right in front of the main camera on the smartphone. the device is covered with sterile transparent drapes (tegaderm®, m corporate, st. paul, mn, usa). a light source is connected with a fiber optic cable for endoscopic use. the image can be seen in real time on a common tv screen through an hdmi connection to the smartphone, with a sterile drape. holding the vision system through the scope would guarantee to keep the camera in place without issues. to operate in full screen the vision was digitally zoomed at . , without losing quality (that is more related to the intensity of the light). as a collateral project we built a low cost simulator training box with the same camera to train the surgeon, obtaining a high fidelity and affordable simulation setting. results: we were able to perform the tasks of the fundamentals of laparoscopic surgery curriculum using our vision system with proficiency. in a pig model, we performed a tubal ligation to simulate an appendectomy and we were able to perform basic laparoscopic suturing. no major issue were encountered and small adjustment only were required to have an acceptable, stable and clear view. conclusion: there is growing interest in minimally invasive surgeries among surgeons in lmic, but its adoption has remained limited due to reasons such as high cost of initial set-up, lack of technological backup and limited access to training among others. an affordable laparoscopic camera system will therefore go a long way in improving access to mis in such settings. open. there were no deaths or bile duct injuries in our series. two patients undergoing laparoscopic approach were converted to open ( . %). complications, los, and gender were similar between the two groups. the laparoscopic group were significantly younger and had a significantly longer operative duration (table) . long term outcomes were not available for analysis. laparoscopic and open cholecystectomy appear safe in the setting of short term surgical missions. neither group suffered major complications. both had similar immediate outcomes. los for both groups was surprisingly similar and shorter than larger series which may possibly due to patient selection. given similar immediate outcomes and large burden of disease, the open approach should be considered. however, this cost may be extracted in terms of greater pain or longer recovery time for patients, which may outweigh the benefits. further data is needed to study pain, long term outcomes, and return to work. introduction: minimally invasive surgery relies on optimal camera control for the successful execution of operations. one disadvantage of laparoscopic surgery is that camera control is dependent on a surgical assistant's interpretation of visual cues and ability to predict the next field of focus in addition to verbal commands from the operating physician to provide the optimal view. robot-assisted minimally invasive surgery provides the operating surgeon the advantage of dictating their field of view. this study aims to utilize a video processing algorithm to determine the incidence of improperly centered field of view in laparoscopic vs. robot-assisted surgery. methods: in this study, recordings of minimally invasive resection of rectal cancer ( laparoscopic and robot-assisted surgery) were evaluated. recordings were input into matlab® video processing to generate single frames at each second interval. a single reviewer would indicate the pixel which best determined where the camera should be centered based on positioning of instruments, current action (dissection/hemostasis/traction) depicted in the frame, and previous review of recordings. pixel locations were recorded for subsequent analysis. centered views were determined as those with the identified centered position pixel lying within the center quadrant when frames were split into a uniform grid. in addition, distance of each point to the absolute center of the frame was calculated based on the pixel's x and y positions. results: individual operation data was analyzed for percent of centered pixel locations and pixel distance from the center pixel of the frame. robot-assisted surgery demonstrated higher percentage of centered views over laparoscopic surgery ( . ± . vs. . ± . ; p. ). robot-assisted surgery also demonstrated shorter distances to frame center than laparoscopic surgery ( . ± . vs. . ± . ; p. ). conclusion: robot-assisted surgery aims to resolve conflicts of cooperation that occur between surgeon and assistant in laparoscopic surgery by enabling manual visual control of the operative field by the operating surgeon. this study demonstrates that by eliminating such conflicts, optimal surgical view is more frequently obtained. surg endosc ( ) background/objective: valveless laparoscopic insufflator systems are marketed for ability to prevent loss of abdominal collapse and desufflation during laparoscopy. however, community surgeons raised concern for possible entrainment of room air, including oxygen ( ), with these systems. this study seeks to quantify o and non-medical air entrainment by a laparoscopic valveless cannula system to understand the risk of intraoperative air embolism. a communityuniversity collaborative was created to design a model and test this hypothesis. methods: an artificial abdomen was developed and calibrated to equivalent compliance and intraoperative volume of an average adult abdomen. it was connected to a flow meter, oxygen concentration sensor, and commercially available laparoscopic valveless cannula system. background: further advance of near-infrared (nir) imaging capability into greater clinical usefulness will be helped by the development of new targetable agents. to avoid issues related to dose timing and contamination, compounds that become fluorescent only at the site being targeted would be a significant advance. here we build on earlier laboratory work to show step-wise advance of the agent towards clinical trialling. methods: a novel agent (nir-aza) was tested in ex vivo colorectal specimens using two commercially available systems to determine characteristics in biological tissue. it was then trialled in a large animal cohort (n= ) to determine its performance for both intestinal perfusion assessment and lymph node mapping (both stomach and colon) using again a commercially available optical imaging system and including a direct comparison with indocyanine green. results: the novel agent was easily detectable in biological tissue in the near infrared wavelength relevant to commercial instrumentation both as a local depot tattoo and as a lymphatic tracing agent. porcine model trialling again showing excellent detection and tracking characteristics both in the circulation and in gastrointestinal tissue with clear tracking to relevant lymph nodes within minutes evident with the latter. while these studies were non-survival, there was no evidence of local tissue or systemic system toxicity in any case. direct qualitative and quantificative comparison between in situ nir-aza and icg at both intestinal and lymph basin regions showed similar levels of fluorescence. conclusion: the trial compound underwent successful testing indicating proof of earlier projected potential. this is encouraging for further work to advance to first in human testing. introduction: enhanced imaging systems have been developed to alter laparoscopic camera output to facilitate visualization during laparoscopic surgery using several novel imaging modes: clara mode reduces overexposure and reflections while brightening darker areas of the image; chroma mode intensifies color contrast to more clearly delineate blood vessels; and a combined chroma-clara mode. the ies also allows the surgeon to change imaging modes throughout the procedure as needed to facilitate different portions of the operation. we hypothesized that this technology would enhance visualization of critical structures during laparoscopic cholecystectomy (lc) compared to standard laparoscopic imaging. methods: videos and still images from an ies (karl storz endoscopy) were assessed in patients undergoing lc using the four imaging modalities. three time points were assessed: ) after adhesions were taken down but before any other dissection; ) after partial dissection of the hepatocystic triangle; and ) after establishment of the critical view of safety (cvs). seven surgeons blinded to the imaging modalities ranked each modality from (best) to (worst) for each of time points ( dissection points for cases). structures identified on achievement of the cvs were also analyzed. all statistics were performed using spss. rank data was analyzed with the friedman and wilcoxon signed rank tests. results: the median ranks of the chroma and chroma-clara imaging modalities (median [iqr] [ ] [ ] [ ] vs ( - ), p= . ) were not significantly different from each other, but both ranked significantly higher than the clara and standard modalities (median rank [iqr] [ ] [ ] and [ ] [ ] , respectively, p. ). individual surgeon preferences varied; four surgeons preferred chroma-clara, two preferred chroma, one preferred clara, and none preferred the standard mode. in addition, the cystic artery and cystic duct were visible in all cases after achieving the cvs, but the common bile duct was visible in only % of cases. conclusion: enhanced imaging system technology provides modalities that were significantly preferred over standard laparoscopic imaging on retrospective review of still and video images during lc. enhanced imaging modalities should be evaluated further to assess their impact on outcomes of lc and other laparoscopic procedures. introduction: cholangiocarcinoma is often diagnosed at an unresectable stage. endoscopic stent placement is generally performed to release the tumor-induced biliary obstruction. however, stents misplacement and migration, tumor tissue ingrowth and cholangitis are relatively frequent complications. energy-based techniques (radiofrequency ablation and photodynamic therapy) have been proposed as alternatives or in addition to the stent placement, showing controversial results. the use of laser sources in the ablation of the biliary wall has not been investigated so far. this study aims at the evaluation of the optimal power and exposure time to achieve a controlled circumferential intraluminal laser ablation of the common bile duct (cbd). methods: through a laparotomy access, the cbd of pigs was exposed and a small choledocotomy was made. a confocal endomicroscopy (ce) scanning (cellvizio) was performed through the choledocotomy, after injection of ml of sodium fluorescein. the . mm diameter circumferentiallyemitting diode laser probe ( nm wavelength) was introduced in the cbd. laser ablation was performed at w during s (n= ) or s (n= ). the power setting was predetermined on preliminary ex-vivo tests on porcine liver specimen. local temperature control was monitored through a fiber bragg grating, embedded in the laser probe. ce scanning was then repeated. the extent of the ablation was measured on hematoxilin-eosin and nadh stained slides. results: the diameter of the probe was too small to enable a single-shot circumferential ablation. there were no full-thickness perforations. after s from turning laser on, the temperature at the application site reached a plateau with minimal oscillations, and remained at mean values of . ± . °c during both and min. histology revealed that the mucosa ablation, at the contact areas, induced a consistent cellular necrosis (nadh-). ce scanning provided real-time images with a specific aspect of the post-ablation mucosa, including an alteration of the normal glandular structure and a general lack of enhanced imaging. the local application of a circumferential laser source induced a precise and safe mucosa ablation with a long-standing increase in temperature in the cbd, in this experimental trial. however, there is a need of an adapted probe, better fitting the diameter of the cbd to enable a single-shot circumferential treatment. goutaro katsuno, md, phd , yasuhiko nakata, md, phd , nobuyuki kubota, md, phd , teruo kaiga, md, phd , takao mamiya, md , masahiro yan, md , naoaki shimamoto, md , shuichi sakamoto, md, phd ; department of gastrointestinal and minimally invasive surgery, mitsuwadai general hospital, introduction: recently major developments in video imaging have been achieved for performing complete mesocolic excisions (cme) or total mesorectum excisions (tme). indocyanine green (icg) fluorescence imaging is already contributing greatly to making intraoperative decisions for keeping an intact visceral fascial layer, making suitable mesentery division lines and identifying anastomotic perfusions. the aim of this study is to present our experience with laparoscopic procedures for colo-rectal cancers using icg fluorescence imaging (lap icg-fi). patients and methods: we usually use the near-infrared (nir) laparoscopy (stryker corporation, michigan, usa) for lap icg-fi. [indocyanine green fluorescent imaging] visualization of lymph flow: icg ( . mg/ . ml) was injected into the submucosal layer around the tumor at points with a -gauge localized injection before the lymph node dissection. visualization of blood flow: after complete colorectal mobilization, the mesocolon was completely divided at the planned proximal or distal transection line. indocyanine green was injected intravenously and the transection location(s) and/or distal rectal stump, if applicable, were re-assessed in fluorescent imaging mode. results: we experienced lap icg-fi cases with colo-rectal cancer patients. tumor was located at the rectum in of them, at the sigmoid colon in , at the transverse colon in , at the descending colon in , at the ascending colon in , and at the cecum in . tnm stage was -i in patients, ii in , iii in , and iv in . the median (range) age of the patients was ( - ) years with a median (range) bmi of . ( - . ) kg/m . the lymph flow was visualized in patients ( %) intraoperatively. however, a high-quality intraoperative icg lymphangiogram was achieved in patients ( %). in high-quality lymphangiogram, the lymphatic ducts and lymph nodes were clearly visualized in real time, and this proved useful in keeping an intact visceral fascial layer as well as in making a suitable mesentery division line even in the bmi[ patients. a high-quality intraoperative icg angiogram was achieved in all patients. anastomotic perfusion was satisfactory in all cases. in patients ( . %), the use of nir+icg resulted in revision of the proximal colonic transection point before formation of the anastomosis. there were no postoperative anastomotic leakages. no injection-related adverse effects were reported. conclusion: lap icg-fi is a simple, safe and useful tool to help us complete lap cme or tme and check real-time anastomotic tissue perfusion. introduction: recently, the spread of laparoscopic surgery as a standard treatment and the development of information & communication technology have yielded abundant video data of laparoscopic procedures. these data have been accumulated and we can access them anytime, anywhere. however, the direction of how to use the abundant video data are still unclear. conventionally, surgical procedures have been performed based on surgeon's subjective decisions and skills, so called "tacit knowledge". for the purpose of objective analysis of laparoscopic procedures in video data, automatic recognition of surgical tools and understanding of surgical workflow must be the first critical step. we used convolutional neural network (cnn) which is the current trend in machine learning and computer vision tasks. methods: using video database of laparoscopic sigmoid colectomy in our institute, we performed annotation of tools and phases in every frame of the operating videos. for the tool detection, we annotated bounding boxes for both left and right tools in the videos. furthermore, phase annotation was performed by watching the videos in consultation with laparoscopic surgeons. the laparoscopic sigmoid colectomy operation passes through phases; -placement of ports and preparation, -dissection of retrorectal space, -medial approach to ima, -isolation and division of ima, -medial-to-lateral retromesenteric dissection, -lateral mobilization of left colon, -rectosigmoid mobilization, -division of mesorectum, -rectosigmoid resection and anastomosis, -finishing. we used cnn architecture to perform surgical tool detection and workflow recognition. results: we totally labeled tools used in the procedures of laparoscopic sigmoid colectomy and successfully developed tool detection system by cnn. as for surgical workflow, average times of phase - were . , . , . , . , . , . , . , . , . , . min, respectively. workflow recognition system using cnn was also successfully developed, while we needed to extract pure operating scenes in advance for efficient recognition outcomes. we've developed tool detection and phase recognition systems using cnn. we need more datasets to improve the detecting ability for future clinical uses. introduction: surgical environments require special aseptic conditions for direct interaction with the preoperative images and surgical equipment, which hampers the use of traditional input devices. we presented the feasibility of using a natural user interface (nui) for gesture control combined with voice control to directly interact in a more intuitive and sterile manner with the preoperative images and the integrated operating room (or) functionalities during laparoscopic surgery. in this study, efficiency and face validity of using this nui for medical image navigation and remote control during the performance of a set of basic tasks in the or will be assessed. methods and procedures: twenty experienced laparoscopic surgeons participated in this study. they performed basic tasks in the or focused on the interaction with a medical image viewer (osirix; pixmeo) and with the functionalities of the integrated or (or ; karl storz). these tasks were carried out by means of traditional manual interaction, using a computer keyboard and mouse and a touching screen, and using a gesture control sensor (myo armband) in combination with voice commands. this nui is controlled by the tedcube system (tedcas medical systems). time required to complete the tasks using each interaction method was recorded. at the end of the tasks, participants completed a questionnaire for face validation and usability assessment. results: the use of the nui required significantly less time than conventional manual control to show preoperative studies and information for surgical support. however, the interaction with the medical image viewer was significantly faster using the traditional input devices. participants evaluated the nui as an intuitive, simple and versatile tool that improves sterility during surgical activity. seventy-five percent of the participants would choose the gesture control system as a method of interaction with the patient's preoperative information during surgery. conclusions: the presented gesture control system allows surgeons to directly interact with preoperative imaging studies and the functionalities of an integrated or during surgery maintaining the aseptic conditions. for the traditional manual interaction, it is necessary to take into account the possible reaction time and displacement time of the technician to execute the surgeon's requests. a more personalized medical image viewer is required and with higher integration with the capabilities of the presented gesture control system. emma k gibson, bs, jacqueline j blank, md, timothy j ridolfi, introduction: following a generous left hemicolectomy an anastomosis between the transverse colon and rectum may be required. extensive mobilization and retroileal routing is sometimes necessary to create a tension-free anastomosis. retroileal routing is a technique in which a window is created in the ilieocolic mesentery. the colon is routed through this window, beneath the ileum, prior to entering the pelvis. retroileal routing is uncommon and there is no data on this technique when performed in using a hand-assisted laparoscopic technique. the aim of this study was to review our experience with hand-assisted laparoscopic left sided colon resections including retroileal routing of the proximal colon to the rectum. methods and procedures: we performed a retrospective review of a single surgeon's experience with hand-assisted laparoscopic left sided resections over a seven-year period from - . indication for operation, basic demographics, bmi, procedure time, short-and long-term morbidity, and mortality were recorded. results: a total of patients underwent a hand-assisted laparoscopic left sided resection with a colorectal or coloanal anastomosis. of these, underwent hand-assisted laparoscopic procedures with retroileal routing of the proximal colon. in each case, operations included a midline hand port incision and two mm ports in the lower abdomen. the indications for operation were diverticular disease and neoplasm in nine and four patients respectively. procedures took an average of . ( - ) minutes to complete. postoperative morbidity included intubation for co retention in one patient and a rll effusion in another patient. there were no anastomotic leaks and there were no -day or -day mortalities. conclusion: retroileal routing of the colon following left hemicolectomy occurs infrequently. a hand-assisted laparoscopic approach appears to be a safe and efficient in these technically challenging cases. objective: approximation of the diaphragmatic crus pillars is a key step in hiatal hernia repair. the dogma of successful hernia repair requires tension free approximation of tissue. there are no techniques described to measure tension across the crus closure. aim of this study is to describe a novel technique for measuring the tension exerted on crural sutures and report initial findings. methods: data was collected at institutions by the same surgeon. after hiatus dissection was complete the crus defect was measured both anterio-posterior and transverse dimension. the crus closure sutures were placed posterior and then lateral to the esophagus. the initial suture is started posteriorly with a figure of eight fashion (# ). with each subsequent stitch placed anteriorly (# and # ) or laterally (l , l ) till adequate hiatus closure is achieved. we measured tension on each suture placed as follows. conclusions: the autolap system provides improved image stability, staff interactions, and enhanced ergonomic comfort for the surgical team. it also offers cost-savings from decreased staffing requirements for hospitals that routinely use staff camera holders. the system set up of - min was less variable after cases, representing the learning curve. in addition, our approach identified problems with the system that require improvement by the manufacturer. notably, we identified significant ergonomic problems for human camera holders, which has been previously described and can be addressed by this device. background: gastric leaks continue to be a troubling predicament for physicians and patients alike. they are especially concerning after bariatric surgery. electrolyte abnormalities and dehydration continuously pose a life threatening problem in these patients. methods: this is an irb approved retrospective review of our experience with a biologic tissue mesh plug closure of gastric leaks. our interventional radiology colleagues percutaneously accessed the perigastric collection with a wire and a straight catheter was guided through the gastric wall defect and advanced over the wire until it was intraluminal. the surgeon then placed an endoscope down to the level of the gastric defect. the wire was then retrieved by the endoscope achieving percutaneo-oral wire access. the biologic tissue matrix was then measured and cut to a square and inverted into a cone like structure with a flat straight piece on the open end. the cone patch was then secured to the wire with braided polyglactin suture loop. the wire was then withdrawn back through the gastric defect pulling the plug and patch into position and placement was confirmed by endoscopy. results: we attempted closure of a gastric leak arising after bariatric surgery in six patients. five underwent successful deployment while one had premature disconnection of the plug from the wire and could not be deployed. the five who had successful deployment had immediate success and within days resumed enteral intake of liquids and resolution of the leak. two of the six patients additionally underwent covered stent placement to stent a stenotic area at the incisura angularis from the esophagus to the antrum. this stent was typically removed - weeks later. there were no complications related to the procedure or the plug. only one patient has undergone repeat endoscopy to evaluate the status of the plug. in that patient an ulcer at the plug site was visualized one month after the procedure. three months later endoscopy showed the clean ulcer had shrunk to half of the original ulcer size. conclusion: this novel minimally invasive technique utilizing ir and endoscopic placement of a biologic mesh plug into gastric leaks after bariatric surgery has been highly successful in treating chronic and subacute gastric leaks. we recommend that these endoscopic techniques be used to close gastric defects prior to operative intervention. introduction: laparoscopic surgery has spread worldwide and become a standard procedure among many abdominal surgical fields. the incidence of postoperative adhesion, which is a typical postoperative complication, is considered low compared with that after laparotomy, but once complications develop, such as adhesion-induced intestinal obstruction and chronic abdominal pain, the low-invasiveness of laparoscopic surgery may decrease markedly. while we have previously used a sheet-type absorbable barrier to prevent adhesion, it requires a technique in many cases when it is applied in the abdominal cavity. in this study, we used a spray-type absorbable barrier, which is considered simple to apply, as an adhesion-preventing absorbable barrier following laparoscopic surgery. subjects and methods: a spray-type absorbable barrier for prevention of adhesion (ad spray type l®) was applied to the dissected surface, port region, and beneath the small incised wound in patients who underwent laparoscopic surgery of the large intestine after february . the nozzle is long ( mm in length) and the angle of the tip is adjustable to some extent, so that the spray could be applied easily to the target region, even in areas in which it would be difficult to secure a work space, by rotating the shaft and finely adjusting the angle of the tip. in order for the barrier to remain in the target region, this preparation must remain viscous after application. discussion: approaches for the insertion and affixing of a conventional sheet-type absorbable barrier for the prevention of adhesion has been reported previously by various researchers. the adhesion-preventing absorbable barrier used in this study was a spray type with a long nozzle, which may have been useful because it made the laparoscopic application easy. however, its application requires some experience and time for preparation compared with the use of the sheet type, which could be disadvantageous. further accumulation of cases, including evaluation of prevention of adhesion after use of the adhesion-preventing absorbable barrier may be necessary. christopher g yheulon, md, priya rajdev, md, s. scott davis, md; introduction: evidence has demonstrated that biosynthetic glue for laparoscopic inguinal hernia repair results in decreased pain. however, the two glue sub-types (biologic-fibrin based; synthetic -cyanoacrylate based) have never been compared. this study aims to assess the outcomes of those subtypes. method and procedures: a systematic review of the medline database was undertaken. randomized trials assessing the outcomes of laparoscopic inguinal hernia repair with penetrating and glue fixation methods were considered for inclusion and data analysis. thirteen trials involving patients were identified with eight trials utilizing fibrin and five trials utilizing cyanoacrylate. results: there were no differences in recurrence or wound infection between the glue subtypes when compared individually to penetrating fixation alone or indirectly to each other. there was a significant reduction in urinary retention with fibrin glue when compared to penetrating fixation (or . , % c.i. . - . ). no studies utilizing cyanoacrylate analyzed urinary retention as an outcome. there were non-significant trends in reduction of hematoma and seroma for both glue subtypes when compared to penetrating fixation (or . , % confidence interval . - . ). conclusions: glue fixation in laparoscopic inguinal hernia repair reduces the incidence of urinary retention and may reduce the rate of hematoma or seroma formation. as there are no differences in outcomes when comparing fibrin or cyanoacrylate glue, surgeons should choose the glue that is available at the lowest cost at their respective institution. however, improvement of the optical system is necessary to further utilize this advantage. we are developing an optical lens system covering the range from macroscopic to microscopic. methods: we developed a handheld prototype created by combining the objective lens system of an optical microscope and a telescope lens. a feasibility study using a porcine model was conducted. macroscopic observation was done at a distance followed by microscopic observation in contact with tissue. first, we observed the operative field macroscopically. we then observed the serosa of the small intestine microscopically, and effects of blood flow occlusion were studied. results: ( fig. and fig. ) the same visual field as ordinary laparoscopy was achieved during macroscopic observation, while using microscopic observation it was possible to observe the complex peristaltic movements of the intestine. the minute blood vessels of the visceral peritoneum and larger, deeper blood vessels were also observed. when the mesenteric vessels were occluded, changes in peristaltic movement were seen directly. congestion in blood vessels in the deep layers of the serosa was observed. improvement in peristalsis and congestion were confirmed by restoring blood flow. this system enables direct visual observations not possible with conventional optics. this system can be utilized in both laparoscopic and open surgery. the microscopic visual information obtained by this system may help with intra-operative decision making and serve to facilitate safe and precise surgery. introduction: accurate, real-time visualization is critical for efficient, effective and safe surgery. although optical imaging using near-infrared (nir) fluorescence has been used for visualization of anatomic structures and physiologic functions in open and minimally invasive surgeries, its efficacy and adoption remain suboptimal due to the lack of specificity and sensitivity. herein, we report a novel class of compounds, which are exclusively metabolized in liver or kidney, rapidly excreted into to biliary or urinary systems, and emitted two different nir fluorescence spectrums. methods: novel, water-soluble heptamethine cyanines; compound x (biliary) and compound y (urinary), unreactive towards gluthathione and the cellular proteome were synthesized, and visualized using real-time, dual-color nir imaging device. sprague-dawley rats (n= ) and yorkshire pigs (n= ) were used to demonstrate and validate its usefulness, distributed into a control group (icg; rat n= , irdye cw rat n= ), a biliary group (compound x; rat n= , pig n= ), a urinary group (compound y; rat n= , pig n= ), and dual-labeling group (compound x&y; rat n= , pig n= ). each rat and pig received one or two of the compounds at optimized dose of . -mg/kg intravenously, fluorescence signals and bio-distributions were monitored and recorded over time. the target to background ratio (tbr) was calculated in each target systems and compared to assess sensitivity and specificity. results: compound x was rapidly cleared from liver within min after intravenous injection while the fluorescence signals in biliary system lasted up to h both in rats and pigs. compound y showed significant renal excretion up to h and the urinary signals remained up to h. they were both highly specific to target organs with tbr values of . (biliary), . (urinary) and . (cf. icg) at peak signals. these new compounds have approximately - times higher quantum yields than icg and . - . times higher specificity to kidney and liver than irdye cw. one-way anova showed significant differences between control, biliary, and urinary group (p. .) dual-labeling results also showed a complete separation of these two metabolic systems (p= . ) and a real-time display of these two systems were clearly visualized with pseudo-colored labeling inside the animal body. conclusion: we report a new generation of organ-specific, real-time fluorescent markers for intraoperative visualization, navigation and potential geo-fencing. these new compounds have significantly higher quantum yields and higher specificity to visualize kidney and/or liver than any currently available reagents. background: porcine models have been widely accepted for gastrointestinal surgery studies, due to their similarities to human anatomy, histology and physiology. devices such as laparoscopic staplers have been widely used in bariatrics and are currently the cornerstone of bariatric. there are currently few published articles regarding surgical stapler testing in porcine models by means of a survival design. the purpose of this study is to present a new model for stapler testing in porcines. we present the following study in which we asses a novel stapler's feasibility and safety, and its compatibility to currently used stapler reloads. this novel stapler, the aeon™ endoscopic linear stapler (lexington medical inc., billerica, ma. pending fda approval), has been previously tested in-vitro and in-vivo by the lexington medical engineering department in matters of mechanical function, staple line bursting pressure, staple formation and hemostasis. duffy et al. used this instrument for small bowel anastomoses in a two-week survival study in porcine models. methods and procedures: four porcine animal model was used under iacuc protocol for a -day survival study held at the fiu (doral, fl, u.s.a) research facility. all animals underwent sleeve gastrectomy using the novel stapler handle, combined with the endo gia™ (medtronic, mansfield, ma) mm-staple reloads in two of the animals and aeon™ mm-staple reloads in the remaining two. no reinforcements or oversewing of the staple line was done. these procedures were performed by two bariatric surgeons. animals were monitored perioperatively by the facility staff as per protocol. the animals were euthanized at day . post-mortem assessments were done blindly. gross evaluation and comparison of the gastric tube and their staple lines was done, as well as patency, strictures, and staple line integrity. results: stapler function was equivalent with both reload brands, no technical issues were encountered. - firings were used per animal. no intraoperative complications related to stapler function ensued. no postoperative complications were encountered. all animals survived the full length of the study- days. all sleeves were patent, no strictures or bowel obstruction were present. conclusions: in an animal survival study, a follow-up period of weeks appears to be a good benchmark for stapler testing. the use of the novel stapler for gastric resections appears feasible and safe. further studies such as microscopic examination of the staple lines, might help confirm equivalence, safety and feasibility of these products for the sleeve gastrectomy procedure. jason m samuels, md , peter einersen, md , krzysztof j wikiel, md , heather carmichael , douglas m overby , john t moore , carlton c barnett , thomas n robinson, md , teresa s jones , edward l jones, md ; university of colorado denver, denver va medical center introduction: the purpose of our study was to evaluate the impact of smoke evacuation devices on operating room fires caused by surgical skin preps. surgical fires are rare but preventable events that cause devastating injuries. alcohol-based surgical skin prep serves as the fuel for a fire ignited by electrosurgical instruments. we hypothesized that increasing air exchanges near the tip of the active electrode will reduce the concentration of alcohol thus reducing the incidence of surgical fires. methods: a standardized, ex vivo model was created with a cm section of clipped, porcine skin. surgical skin preparations tested: % isopropyl alcohol with % chlorhexidine gluconate (chg-ipa) and % isopropyl alcohol with . % iodine povacrylex (iodine-ipa). based upon previous studies, a high-risk situation was replicated with immediate energy activation in the presence of pooled alcohol-based prep. the site was draped to simulate a small surgical procedure with approximately square cm exposed. (figure ) a standard and smoke evacuating electrosurgical pencil was activated for s on w coagulation mode in the presence of % oxygen. a standard wall suction was also tested with the tip held cm from the tip of the electrosurgical pencil. a chi-square test was used to compare differences between groups. results: surgical fires were created in % ( / ) of the tests with the chg-ipa and % ( / ; p= . ) of the tests with iodine-ipa. continuous wall suction did not change the incidence of fire. the smoke evacuation electrosurgical pencil significantly decreased the incidence of fire when compared to the standard pencil and continuous wall suction for both preparations (table ) . with chg-ipa, the smoke evacuation electrosurgical pencil decreased the frequency of fire by % (figure , p. ). similarly, when using iodine-ipa, the electrosurgical pencil with integrated smoke evacuation demonstrated a % decrease in fires (figure , p. ). conclusion: alcohol-based skin preps fuel surgical fires. the use of a smoke evacuator electrosurgical pencil reduces the occurrence of surgical fires. elimination of alcohol-based preps and the use of smoke evacuation devices decrease the risk of operating room fires. brian bassiri-tehrani, md, netanel alper, md, jeffrey s aronoff, md, yaniv larish, md; lenox hill hospital ureteral stents have historically been used in pelvic surgery when anatomical or clinical considerations warrant urological expertise to aid in identifying the ureters. in the colorectal and gynecologic surgery literature, prophylactic ureteral stents appear to increase the ability to detect ureteral injuries while not being shown to prevent such injuries. with the increasingly widespread use of laparoscopy and the robotic platform in complex colorectal and pelvic surgery, the utility of stents remains unclear. one of the limiting factors regarding the use of ureteral stents in minimally invasive surgery is the lack of tactile feedback; the inability of the surgeon to directly palpate the stents. one proposed method to overcome this deficiency has been the use of lighted ureteral stents. increased operating time, increased cost, and need for specialized equipment are potential drawbacks of lighted stents. an alternative to using lighted stents in minimally-invasive surgery is to directly inject indocyanine green (icg) into the ureters after cystoscopy-guided placement of ureteral stents. intraoperative visualization of the ureters is acheived by using either the pinpoint endoscopic fluorescence imaging system in laparoscopy, or firefly integrated with the robotic platform. it is hoped that the risk of inadvertent ureteral injuries during colorectal and pelvic operations will be minimized using this technique, due to improved visualization of the ureters throughout the procedure. in this case presentation, we describe a novel use of icg in a patient undergoing a laparoscopic surgery for resection of a . . . cm pelvic mass abutting the bladder, sigmoid colon and left ureter. preoperatively, there was concern that the mass would be intimately adherent to, or even invading, the bilateral ureters based on ct scan findings. after ureteral injection of icg, visualization of both ureters was easily achieved at the time of operation, and the procedure proceeded with careful and safe dissection of the mass with visualization of the ureters at all times. though there is a paucity of studies evaluating the use of icg in the laparoscopic modality, this technique was safe, easy to employ, inexpensive and very useful to visualize the ureters intraoperatively. indeed, larger studies with appropriate sample sizes would help to further validate this novel use of icg. university of colorado -denver, va eastern colorado healthcare system introduction: operating room fires are "never events" that expose the patient to the risk of devastating complications. our group has previously demonstrated that alcohol-based surgical skin preparations fuel operating room fires. manufacturer guidelines recommend a three-minute delay after application of alcohol-based preps to decrease the risk of prep pooling and surgical fires. the purpose of this study was to evaluate the efficacy of the three-minute dry time in reducing the incidence of surgical fires. methods and procedures: a standardized, ex vivo model was used with a cm section of clipped, porcine skin. alcohol-based surgical skin preparations tested were % isopropyl alcohol (ipa) with % chlorhexidine gluconate (chg) and % ipa with . % iodine povacrylex (iodine-ipa). nonalcohol-based solutions included % chlorhexidine gluconate and % povidone-iodine "paint." an electrosurgical ''bovie'' pencil was activated for seconds on watts coagulation mode in % oxygen, both immediately and minutes after skin preparation application, with and without solution pooling. results: no fires occurred with immediate testing of nonalcohol-based preparations ( / ). alcohol-based preps created flames on immediate testing in % ( / ) of cases when pooling was present. without pooling, flames occurred in % ( / ) of cases on immediate testing. after a -minute delay, there was no difference in the incidence of fire when pooling was present ( / vs. / , p [ ) . similarly, there was no difference when pooling was not present ( / vs. / , p= ). (table ) conclusions: alcohol-based surgical skin preparations fuel surgical fires. waiting minutes for drying of the surgical skin prep did not change the incidence of surgical fire (regardless of whether there was pooling of the prep solution). the use of nonalcohol-based skin preps eliminated the risk of fire. introduction: laparoscopic port sites are associated with a significant incidence of long-term hernia formation. in addition, closure with closed loop suture may lead to increased post operative pain thereby limiting patient mobility. the development of novel trocar closure systems could offer a pathway towards quality improvement and warrants investigation. we performed a randomized controlled trial comparing a novel anchor based system (neoclose®) versus standard suture closure. methods: a prospective randomized controlled trial of patients undergoing port site closure following robotic assisted laparoscopic sleeve gastrectomy or gastric bypass was completed ( with neoclose® device and with standard laparoscopic suture closure). each patient had both the camera port and stapling port closed ( port sites in each group). primary outcome measures included the incidence of hernia ( week ultrasound), time for port site closure, and depth of needle penetration. secondary outcome measures were analog pain scoring at post op day , week and week . results: physical exam as well as ultrasound evaluation showed no hernias in either group at weeks. when compared to suture closure, the neoclose® device was associated with shorter closure times ( . ± . versus . ± . s, p. ) and needle depth penetration ( . ± . versus . ± . cm, p\ . ). the neoclose® device was associated with decreased pain at week after the operation (analog pain score . ± . versus . ± . , p. ). no difference in pain scoring was observed on post operative day or at week . conclusions: trocar site closure with the neoclose® device is associated with decreased closure times and needle depth penetration. no difference in the incidence of hernias was identified very early after operation. the neoclose® device led to decreased pain week after trocar closure which is potentially secondary to decreased tension when compared to closure with closed loop suture. long term hernia data ( year) is pending with patients scheduled for follow up physical exams and ultrasounds. federico gheza, md, mario a masrur, md, simone crivellaro, md; uic introduction: robotic instruments provides a better ergonomics during suturing compared to standard laparoscopy. minimally invasive procedures with limited need of few suture may benefit from an economically affordable device able to overcome some limitations of laparoscopic suturing. flexdex surgical recently obtained the fda approval for human use of its articulated laparoscopic needle driver. the official training provided by the company (available at https://flexdex.com/register-for-training) is a h basic dry lab. the training curriculum as well as the accreditation process is not well structured. no literature is available today on this matter. our goal was building a dedicated training, to allow a safe and predictable early use in humans. methods and procedures: the training module design and implementation was done in our minimally invasive laboratory. in the preliminary phase we define with a small group of residents and research specialists a short list of mandatory concepts to detail showing the instrument. a simple suturing task was then performed by the same group with the new device, laparoscopically and with the robot, available in our lab for training only. a more complex task, based on a dedicated self-designed high-fidelity model of urethral anastomosis was then proposed, exploring different options (one flexdex only vs two flexdex, surgeon vs assistant holding the camera). lastly, we applied the new device in animals to evaluate the usefulness of including simple tasks or entire procedures in the training curriculum. results: we were able to define a multilevel, adaptable training module including a basic information session, a dry lab with inanimate low-and highfidelity models and a pig lab. subjects with different level of expertise (medical student, resident, fellow, expert and very expert surgeon) were involved to have an extensive feedback. however, our main focus was to design a training module for laparoscopic and robotic surgeons, to safely introduce the flexdex in their practice. the only outcome for this preliminary work was collected through a "post exposure" survey. the expert surgeon that did the entire training was able to give feedback after his first application of the device in humans as well. conclusions: flexdex is a promising device, available in the united states in approved facilities only. a minimally invasive lab with high laparoscopic and robotic training experience is the ideal setting to build a curriculum. a first adaptable, multilevel, original, high-fidelity training is proposed to be validated with further studies and could be implementable for accreditation purposes. surg endosc ( ) :s -s augmenting spatial awareness in laparoscopic surgery by immersive holographic mixed reality navigation using hololens objectives: endoscopic minimally invasive surgery provides a limited field of view, thus requiring a high degree of spatial awareness and orientation. because of a d field of endoscopic view, a surgeon's spatial awareness is diminished. this study aims to evaluate the efficacy of our novel surgical navigation system of immersive holographic mixed reality (mr) using a head-mounted smart glass display hololens to enhance spatial awareness of the operating field in laparoscopic surgery. the authors describe a method of registering and overlaying the preoperative mdct imaging localization of tumors, vessels, and organs onto the real world in the operating theatre through holographic smartglasses in augmented reality (ar). methods: in this study we included laparoscopic gi, hpb, urology, and gynecologic surgeries using this system. we developed a ct-based patient-specific holographic mr surgical navigating application using hololens, that is a pair of see-through monitors built-in head-mounted display. by reconstructing the patient-specific d surface polygons of tumors, vessels, and organs out of the patient's mdct, mr anatomy was displayed on the see-through grasses three-dimensionally during actual surgery. the hololens features an inertial measurement unit which includes an accelerometer, gyroscope, and a magnetometer for environment understanding sensors, an energy-efficient depth camera, a photographic video camera, and an ambient light sensor. results: the accurate surgical anatomy of size, position, and depth of the tumors, surrounding organs, and vessels during surgeries could be measured using build-in dual infrared light sensors. the exact location between surgical devices and patient's anatomy could be traced on the pair of mr smart-glasses by satellite tracking. the gesture controlled manipulation by surgeons' hands with surgical groves was useful for intraoperative anatomical references of tumors and vascular position under sterilized environment. it allowed the user to manipulate the spatial attributes of the virtual and real anatomies. this system reduced the length of the operation and discussion time. this could support complex procedures with the help of pre-and intra-operative imaging with better visualization of the surgical anatomy and spatial awareness with visualization of surgical instruments in relation to anatomical landmarks. conclusions: the immersive holographic mr system provides a real-time d interactive perspective of the inside of the patient, accurately guiding the surgeon. this helps spatial awareness of the surgeons in the operating field and has illustrative benefits in surgical planning, simulation, education, and navigation. enhancing scene visualization is a feasible strategy for augmenting spatial awareness in laparoscopic surgery. francisco miguel sánchez margallo, phd , juan a. sánchez-margallo, phd , andreas skiadopoulos, phd , konstantinos gianikellis, phd ; minimally invasive surgery centre, cáceres, spain, university of nebraska at omaha, university of extremadura, spain introduction: new handheld devices have been developed in order to address the technical limitations and ergonomic issues present in laparoscopic surgery. the aim of this study is to analyze the surgeon's performance and ergonomics using the radius r drive instruments (tubingen scientific medical, germany) during the execution of laparoscopic cutting and suturing tasks. methods and procedures: three experienced laparoscopic surgeons performed both an intracorporeal suturing task and a cutting task on a box trainer. both tasks were repeated three times. a maryland dissector and a pair of scissors were used for the cutting task. for the suturing task, a maryland dissector and needle holder were used. conventional laparoscopic instruments and their equivalent r drive instruments were used. the order in the use of the type of instruments was randomized. execution time and surgeon's ergonomics were assessed. for the latter, surface electromyography (trapezius, deltoid and paravertebral muscles) and the nasa-tlx index were analyzed. for the cutting task, the percentage of the area of deviation from the cutting pattern (% of error) was assessed. the suturing performance was assessed by means of a task-specific validated checklist. results: surgeons required more time to perform both laparoscopic tasks using the r drive instruments. the use of both instruments had a similar percentage of deviation from the exterior part of the cutting pattern. however, the deviation from the inner part was significantly higher using the r drive instruments (conv: . ± . % vs r drive: . ± . %; p\. ). needle driving was scored lower using the r drive instruments, but quality of knot tying was similar to conventional instruments. the use of r drive increased the muscle activity of the trapezius muscles bilaterally for both laparoscopic tasks. this muscle activity also increased for the left deltoid muscle during the cutting task. surgeons stated that the use of r drive instruments leads to a higher mental and physical workload when compared to traditional laparoscopic instruments. conclusions: despite the novel and ergonomic design of the r drive laparoscopic instruments, the results of this study suggest that an improvement in surgical performance and physical workload is required prior their use in an actual surgical setting. further studies should be done to analyze the use of these instruments during other laparoscopic tasks and procedures. we believe that surgeons need a longer and comprehensive training period with these laparoscopic instruments to reach their full potential in laparoscopic practice. background/objectives: d printing has been shown to be a useful tool for preoperative planning in various surgical disciplines. however, there are only several single case reports in the field of liver surgery. this is because of problematic visualization of anatomy, difficulties in methodology and-most importantly-high costs limiting implementation of d printing. the goal of this study is to evaluate the utility of personalized d-printed liver models as routinely used tools in planning and guidance of laparoscopic liver resections. materials and methods: contrast-enhanced computed tomography images of consecutive patients who underwent laparoscopic liver resections in a single centre were acquired and processed. proper segmentation algorithms were used to obtain virtual models of anatomical structures, including vessels, tumor, gallbladder and liver parenchyma in stl (stereolithography) format. after processing files, models in parts were subsequently printed with desktop ultimaker + (ultimaker, netherlands) d printer, using polylactic acid filaments as printing material. all parts were matched together to create a mold, which was later casted with transparent silicone. models were delivered to surgical teams prior to the surgery as well as used in patients' education. results: up to now, six full-sized, transparent, personalized liver models were created before laparoscopic liver resections and used as a tool for preoperative planning and intraoperative guidance. usefulness of these models has been evaluated qualitatively with surgeons. operative data was obtained for each patient and it will be used for quantitative analysis in further study phases. costs of one model varied between $ and $ and whole process of development took approximately days in every case. conclusions: d-printed models allow precise planning in complex cases of minimally invasive liver surgery by providing high-quality visualization of patient-specific anatomy. implementation of this technology might potentially lead to clinical benefits, such as reduction of operative time or improvement of short-term outcomes. having said that, more data is needed to decisively prove these hypotheses. introduction: modern laparoscopic graspers may risk inadvertent injury to tissues, and have been shown to produce crush and puncture injuries. in addition, the force transmitted to the tissues by grasper handles can be highly variable, dependent on the orientation and amount of tissue engaged by the grasper. we have developed a novel vacuum-based laparoscopic grasper designed to reduce tissue injury from grasping. the aim of this study is to compare the incidence and severity of tissue trauma caused by vacuum-based graspers versus standard compressive graspers while manipulating tissue. we performed an in vivo surgical porcine study to assess gross and histologic tissue injury after grasping trials. grasping trials were divided equally between two adult porcine models; samples of small bowel were grasped with a standard atraumatic laparoscopic grasper (aesculap double-action atraumatic wave grasper) and were grasped with our novel vacuum grasper with varying vacuum head designs ( for head a, each for heads b and c). following grasping, the porcine model was allowed to dwell for hours prior to harvest. gross injury was graded as follows: ) no injury, ) ecchymosis only, ) serosal injury, ) seromuscular injury, and ) perforation. histologic injury was graded as follows: ) serositis, ) partial-thickness injury to the muscularis propria (mp), ) full-thickness mp injury, and ) full-thickness mp and mucosal injury. mann-whitney u test was performed to compare both gross and histologic injury scores between the groups. results: on gross assessment, no samples were noted to have injury more severe than ecchymoses following grasping. the vacuum grasper was found to cause more ecchymosis (median= ) than the compressive laparoscopic grasper (med.= , u= , p. ). on histologic assessment, the compressive grasper caused significantly more severe injury (med.= ) compared to the vacuum grasper (med.= , u= , p= . ). subgroup analysis showed that heads a (med.= , u= . , p= . ) and b (med.= , u= , p= . ) caused significantly less injury compared to the compressive grasper. head c (med.= , u= . , p= . ) also showed less injury but did not reach statistical significance. conclusion: this study demonstrates that our novel laparoscopic vacuum grasper produces less tissue trauma than standard compressive graspers. vacuum-based grasping is a viable alterative for reducing inadvertent tissue injury in laparoscopy. minimally invasive surgery centre, cáceres, spain, university of nebraska at omaha, university of extremadura, spain introduction: the aim of this study is to analyze the surgeon's performance, workload and ergonomics using an ergonomically designed handheld robotic needle holder during laparoscopic urethrovesical anastomosis in an animal model, and comparing it with the use of a conventional laparoscopic needle holder. methods and procedures: six experienced surgeons performed an urethrovesical anastomosis in a porcine model using a handheld robotic needle holder and a conventional laparoscopic axialhandled needle holder (karl storz gmbh). the robotic instrument (dex®, dextérité surgical) has an ergonomic handle and a flexible tip with unlimited rotation, providing seven degrees of freedom. the use of the surgical instrument was randomized. for each procedure, an expert surgeon evaluated the surgical performance in a blinded fashion using the global operative assessment of laparoscopic skills rating scale. besides, the quality of the intracorporeal suture was assess by a validated suturing-specific checklist. the surgeon's posture was recorded and analyzed using the xsens mvn biomech system based on inertial measurement units. the surgeon's workload was evaluated by means of the nasa task load index, a subjective, multidimensional assessment tool. the patency of each anastomosis was assessed using methylene blue. results: all urethrovesical anastomoses were completed without complications. only one anastomosis with the robotic device failed the patency test. surgeons showed similar surgical skills with both instruments, although they presented greater autonomy with the conventional instruments (p =. ). for the suturing performance, the use of the robotic device led to an increase in the number of movements during the needle driving and lower tendency to follow its curvature during the withdrawal maneuver (p=. ). the level of workload increased with the robotic device. however, the surgeon's satisfaction with the surgical outcome did not differ using both instruments. the use of the robotic instrument led to similar posture of the shoulder and wrist and better posture of the right elbow (p=. ) when compared to the conventional instrument. conclusions: the use of the robotized needle holder obtained similar results for the surgical performance and surgical outcome of the urethrovesical anastomosis when compared to the conventional instrument. we consider that aspects such as the surgeon's autonomy, dexterity in driving the needle and workload could be improved with a comprehensive training with the new device. inertial sensors can be an alternative for actual and crowded surgical environments. surgeons acquired a better body posture using the novel robotic needle holder. surg endosc ( ) :s -s introduction: temporal and spatial tissue temperature profile in electrosurgical devises, such as ultrasonic scissors and bipolar vessel sealing system, was experimentally measured, and the incidence of postoperative complications after thoracoscopic esophagectomy was assessed according to the electrosurgical devises used. methods and procedures: experiment of thermal spread: sonicision (sonic) was used for ultrasonic scissors and ligasure (ls) was used for bipolar vessel sealing system. each device was activated in order to cut porcine muscle at room temperature. temperatures of both the device blade and porcine tissues beside the device were measured using a temperature probe. each experiment was performed at least three times. room temperature was degrees. clinical analysis: the patients who underwent thoracoscopic esophagectomy with -field lymph node dissection in the prone position were selected in the study. incidence of postoperative complications after thoracoscopic esophagectomy was compared according to electrosurgical devises. bronchoscopy was used for diagnosis of recurrent laryngeal nerve paralysis (rlnp). sonic and ls was employed in and patients, respectively. material: we compared consecutive cases using d laparoscopic surgery versus cases of d conventional laparoscopic surgery from january to june . all surgical procedures were performed by experienced laparoscopic surgeons using d (einsteinvision system) and hd conventional laparoscopic optic. d-laparoscopic surgery offers the depth perception of the surgical field that is lost with the conventional ( d) laparoscopic surgery, and in many series is reported to be better in terms of surgical performance. outcome measures was operation time, surgical performance, blood looses, complications and surgeon satisfaction with the procedure. results: cholecystectomy was the most frequent surgery performed with cases ( %); hernia surgery cases ( %); fundoplication cases ( %), appendectomy cases ( %), left colon excison with colo-rectal anastomosis cases( %), and other cases ( %) wich included ovarian cyst excision, liver biopsy, prostatectomy and pediatric surgery. we compared each d procedure with a standard laparoscopy case performed by the same surgeon during the time of the study. d vs d surgical procedures outcome measures are shown in table . we found better results in operation time, surgical performance and less blood looses in favor of three-dimensional laparoscopy (. ). conclusion: d laparoscopy reduces operation time related to better performance during the procedure. depth perception facilitates dissection, intracorporeal knotting, mesh placement and colo-rectal anastomosis. surgeons reported better surgical performance and comfort during d laparoscopy; there were any reported side effects such as headache or dizziness. background: social media (some) uniquely allows international collaboration, with immediacy and ease of access and communication. in areas where surgical management is contentious, this could be a valuable tool to frame the current state, propose best practices, and possibly guide management in a rapid, cost-effective, global scale. our goal was to determine the ability to use twitter-a some platform-as an alternative surgical research tool. methods: twitter was used to host an online poll on a pre-selected controversial topic with no current consensus guidelines-pathological complete response in rectal cancer. an influential colorectal surgeon published the survey "t n rectal cancer undergoes a complete response" on two separate occasions. both polls were open for duration of three days. two methodologies were tested to increase exposure and direct towards relevant participants: first, tagging several worldwide experts, then using the well-established hashtag #colorectalsurgery and publishing during an international surgical conference. the main outcome measure was the feasibility, validity, reproducibility, and methods to further participation of a twitter survey. results: the tweet polls were posted three weeks apart. there was no cost and the time required for the process was three minutes, demonstrating the feasibility. providing three closed options to select from facilitated validity. the poll's anonymity limited knowledge of the participant's qualifications, but public comments and "retweets" came from surgeons with experience ranging from trainee to department chair. a robust volume of respondents was observed. the st post received votes, "likes", "retweets", and comments from a diverse international group ( countries). all tagged members participated in the forum. the nd received votes, "likes", "retweets", and comments. the results were reproducible, with the majority favoring option on both occasions ( % and %, respectively; p= . ). treatment recommendations, their rationale, and open questions were identified in the thread. conclusions: some can be used as a research tool, with valid, reproducible, and representative survey results. while exposure was comparable across the two methods, tagging specific members guided experts to provide more opinions than using conference and specialty hashtags. this could expand awareness, education, and possibly affect management in a transparent, cost-effective method. the anonymous nature of respondents limited the ability to make conclusions, but interest and opinion leaders for further study can be easily identified. this demonstrates the potential for some to facilitate international collaborative research. background: despite the technological advancement of a minimally invasive approach to pylorus -preserving pancreaticoduodenectomy (pppd), the morbidity is still high. among the many complications, postoperative pancreatic fistula (popf) is reported in high incidence rate, which varies from researcher to researcher, and a fistula risk score (frs) has been developed to predict the popf. the aim of this study is validate the fistula risk score in minimally invasive approach of pppd and find the other meaningful parameter for prediction of popf. method and materials: from january to august , laparoscopy attempted right-sided pancreas resection was performed on patients including robotic reconstruction in the division of hepatobiliary and pancreas at yonsei university health system. among them, patients were excluded due to total pancreatectomy (n= ), open conversion (n= ), pancreaticogastrostomy and hybrid manual anastomosis (n= ), non-measurable drain and missing datas (n= conclusions: fistula risk score is significant prediction factor of popf including biochemical leaks. in addition to the previously known frs variables, our data showed that bmi is an important predictor of popf with clinical relavancy in a minimally invasive approach of pppd. laparoscopic hemi-hepatectomy for liver tumor satoru imura, hiroki teraoku, yuji saito, shuichi iwahashi, tetsuya ikemoto, yuji morine, mitsuo shimada; tokushima university introduction: with progress of surgical technique and devices, laparoscopic liver resection became a realizable option for patients with liver tumor. major liver resection such as anatomical left or right hemi-hepatectomy has also been introduced in many centers. herein, we evaluate surgical results of laparoscopic hemi-hepatectomy for liver tumor. patients and methods: until march , consecutive patients who underwent laparoscopic or laparoscope-assisted hemi-hepatectomy (left: , right: ) were reviewed and the surgical data such as operation time, blood loss, postoperative complications were analyzed retrospectively. results: of the patients underwent left hemi-hepatectomy, cases were primary liver cancer, cases were metastatic tumor, and cases were benign tumor. pure laparoscopic surgery was performed in cases. the mean blood loss was ( - ) ml, mean operating time was ( - ) minutes and mean postoperative hospital stay was ( - ) days. the rate of postoperative complications was . % (wound infection; n= ). all right hemi-hepatectomy was performed by laparoscope-assisted method. of the patients underwent right hemi-hepatectomy, cases were primary liver cancer, cases were metastatic tumor, and cases were benign tumor. the mean blood loss was ( - ) ml, mean operating time was ( - ) minutes and mean postoperative hospital stay was ( - ) days. the rate of postoperative complications was . % (biliary stenosis; n= ). the patients with hepatocellular carcinoma were followed up for a median of ( - ) months. recurrence occurred in cases and none of them had died at the time of follow-up. conclusion: laparoscopic hemi-hepatectomy is a safe and effective procedure for the treatment of benign and malignant liver tumors. ibrahim a salama, professor; department of hepatobiliary surgery, national liver institute, menoufia university abstract background: iatrogenic biliary injuries are considered as the most serious complications during cholecystectomy. better outcome of such injuries have been shown in cases managed in a specialized center. objective: evaluatation of biliary injuries management in major referral hepatobiliary center. patients and methods: four hundred seventy two consecutive patients with post-cholecystectomy biliary injuries were managed with multidisciplinary team (hepatobiliary surgeon, gastroenterologist and radiologist) at major hepatobiliary center in egypt over years period using endoscopy in patients, percutaneous techniques in patients and surgery in patients. results: endoscopy was very successful initial treatment of patients ( %) with mild/moderate biliary leakage ( %) and biliary stricture ( %) with increased success by addition of percutaneous (rendezvous technique) in patients ( . %). however, surgery was needed in ( %) for major duct transection, ligation, major leakage and massive stricture. surgery was urgently in patients and electively in patients. hepaticojejunostomy was done in most of cases with transanastomatic stents. one mortality after surgery due to biliary sepsis and postoperative stricture was in cases ( . %) treated with percutaneous dilation and stenting. conclusion: management of biliary injuries was much better with multidisciplinary care team with initial minimal invasive technique to major surgery in major complex injury encouraging for early referral to highly specialized hepatobiliary center. introduction: simple liver cyst is the solitary non parasitic cystic lesion of the liver. teatment of symptomatic liver cyst varies from simple aspiration to hepatic resection. each treatment has its own merits and associatied complications. laparoscopic unroofing (fenestration) offers the best balance between efficacy and safety. polycystic liver disese (pcld) treatment by this method are less clear because of high failure rate. liver resection though more effective carries higher risks. treatment of hydatid disease are controversial. materials and method: simple cyst may be asymptomatic and picked up as incidental findings on ultrasound examination for other abdominal complaints. few cyst have symptoms of mass effect or with complication effect due to haemorrage, rupture, infection. on examination liver is palpable. compression over bile duct give rise to jaundice. the commonest symptoms are pain, early satiety, nausea and vomiting. simple cyst are more common in female after years of age. the cyst located antriorly inferiorly and laterally are the ideal case. investigation like ultrasonography is important. it will helps us to detect the cyst nature, will help to differentiate bet ween simple cyst from poly cystic liver disease, from neoplastic liver. in endemic area of hydatid liver disease serological test is mandatory. ct scan is important regarding details information about to localise the cyst, to identify the liver tissue arroud the cyst, relationship of cyst with the nearby vital structures, number of cyst, calcification and carcinomatous changes in its wall. aspiration of cystfluid, biological and cytological examination to rule out the presence of infection, biliary communication and malignancy. recently, ca - estimation is helpful for the differentiating the simple cyst from the cystadenoma or carcinoma. for jaundice patient ercp is impotant to locate the intraductal polyp causing the biliary obstruction or cyst causes the compression of the biliary tree. for bleeding in cyst mri is helpful. carcinoma at epithelial lining may occur. result: laparoscopic de-roofing (fenestration) less radical procedure ensures adequate drainage of cyst content into the peritoneal cavity. the cyst wall can be removed using harmonic scalpel so smoked produced and fogging of lens can be minimized. the interior surface inspected with care to exclude neoplastic growth and biliary communication. whole operative procedure, duration of postoperative recovery, hospital stay is much shorter in this procedure. large cevron incision can be avoided. no recurrence in two years follow up period. liver resection and total cystectomy theoretically minimizes the recurrence risk but invoke the a real risk of postoperative complications and death. conclusion: careful case selection and meticulous surgical skills are the two major determinants of the outcome. in the llr group, the first port was placed with an alexis® wound retractor (applied medical, usa) and free access® (top corporation, japan) at the abdominal defect made by previous sc. an additional or trocars were placed as needed. results: all patients in the llr group were treated using the laparoscopic approach. there were no other significant differences in patient background and characteristics. operative duration was similar for these groups. blood loss, complication rate, and hospital stay in the llr group were significantly decreased compared with the olr group. conclusion: in concurrent liver resection and sc, the open approach may require multiple large incisions, but the laparoscopic approach can complete procedures with a stoma wound and a few port wounds. additionally, use of a platform on the wound for sc enhances safety and efficacy for dissection of intraabdominal adhesions and a clear operative view. primary hepatic lymphoma: the importance of liver biopsy diego t enjuto , carlos ortiz , laura casanova , jose luis castro , pablo sánchez , jaime vázquez , norberto herrera , benjamín tallon , carmen jimenez ; hospital severo ochoa, hospital san rafael, hospital henares primary hepatic lymphoma (phl) is a very uncommon lymphoproliferative malignancy. it accounts for only . % of all extranodal non-hodgkin lymphoma and . % of all cases of non-hodgkin disease. the diagnosis is made when there is only liver involvement or when there is minimal non-liver disease. bone marrow, spleen, or hematologic affection should be excluded to confirm the diagnosis. we present our experience with two phl's that were correctly diagnosed thanks to laparoscopic liver biopsy. -year-old male admitted because of a -month history of right upper quadrant pain and nonmeasured weight loss. liver function tests and cholestasic enzymes showed normal values. serologic tests showed negative results for both hbv (hepatitis b virus) and hcv (hepatitis c virus). ct (computed tomography) scan showed three intrahepatic lesions in segments v, vi, and vii. ct-guided fine needle did not reach the diagnosis so a laparoscopic hepatic biopsy was performed. the final diagnosis was burkitt-like lymphoma. chemotherapy with r-chop (rutiximab, cyclophosphamide, adriamycin, vincristine, and prednisone) modality was started and completed after cycles. it is currently years since the patient was diagnosed and there are no clinical or radiological signs of recurrence. -year-old male who complained of diarrhoea and abdominal pain. chronic hb infection with no viral charge was detected. ultrasound showed heterogeneity of the whole left hepatic lobe and an mri was performed. a ten by segen centimeters lesion occupying the left hepatic lobe enhanced in arterial phase was seen suggesting adenoma. laparoscopic hepatic biopsy was completed to reach a definitive diagnosis. non-hodgkin lymphoma follicular type has just been confirmed with the histology and immuno-histochemistry. chemotherapy with r-chop should be started in the following weeks. phl's diagnosis is hard to achieve. fine needle biopsies are frequently negative because of the large area of necrosis. surgical biopsies are sometimes indispensable to get enough tissue to reach the diagnosis. phls are sometimes misdiagnosed as hepatocellular carcinoma because of its relation to hcv meaning a major hepatic resection. that is the reason why we consider that all diagnostic measures should be undertaken to rule out a different type of tumor. surgical resection is normally not needed in phls; as they are chemosensitive lesions. surgical options usually add unnecessary morbidity and mortality to these patients. chemotherapy standard treatment for phl consists on r-chop combination. pancreatic neoplasm enucleation -when is it safe? case report and review of the literature elaine jayne buckley , k molik , j mellinger ; siu-som, hshs pediatric surgery introduction: solid pseudopapillary tumors are rare neoplasms accounting for - % of pancreatic malignancies with a low risk of recurrence and metastasis. pancreatic malignancies are less common in pediatric populations, though small case series have identified that pseudopapillary tumors comprise between and % of pediatric pancreatic neoplasms. as these tumors have a low risk of metastasis, the mainstay of treatment has remained surgical excision. several surgical approaches have been described from extensive resections such as pancreaticoduodenectomy to local enucleation. we present a case of enucleation of a large pseudopapillary tumor from the pancreatic head complicated by pancreatic fistula. a literature review was performed given the rarity of this tumor to review surgical approaches, to compare complications and long-term outcomes, and to identify specific strategies to decrease the risk of pancreatic fistula. case description: a year-old female presented with months of abdominal pain. computed tomography identified a right upper quadrant mass felt to be consistent with a lipoma. follow up ct at months suggested the mass was more likely a gastrointestinal stromal tumor (gist), and surgical resection was recommended. enucleation of the mass was chosen in view of a wellcircumscribed appearance, clear operative tissue planes, and concern for long-term morbidity of a more extensive resection given the patient's young age. pathology demonstrated an . cm pseudopapillary tumor with negative margins. her post-operative course was complicated by a grade b pancreatic fistula, managed with nutritional support, external drain maintenance, and endoscopic stenting. the patient achieved healing of the pancreatic fistula after four months. results: our literature review demonstrates no difference in recurrence, mortality or morbidity between types of surgery. pancreatic fistula contributed to the majority of postoperative morbidity in all cases. recommendations for enucleation include small ( - cm) tumors with between and mm margin from the main pancreatic duct. techniques identified to minimized post-operative pancreatic fistula include preoperative imaging of the duct anatomy, preoperative pancreatic stent placement, and intraoperative ultrasound to identify the pancreatic duct. some literature supports preservation of pancreatic parenchyma, particularly in younger patients, to reduce endocrine and exocrine dysfunction given the low rates of recurrence and metastasis with this rare neoplasm. conclusion: our case demonstrates complications of enucleation of a large pseudopapillary tumor with successful multidisciplinary post-operative management. with the risk reduction strategies identified, we suggest that enucleation may be considered for pseudopapillary tumors in younger patients to preserve pancreatic parenchyma and long-term pancreatic function. introduction: recent advancements in minimally invasive techniques led to increased effort and interest in laparoscopic pancreatic surgery. laparoscopic distal pancreatectomy is a widely accepted procedure for left-sided pancreatic lesions. in other cases, the adoption of laparoscopic pancreaticoduodenectomy has been hindered by the technical complexity of laparoscopic reconstruction. hybrid laparoscopy-assisted pancreaticoduodenectomy (hlapd) in which pancreaticoduodenal resection is performed laparoscopically, while reconstruction is completed via a small upper midline minilaparotomy, is combines the efficacy of open approach, and the benefits of laparoscopic approach. the purpose of this study is to report our experience of hlapd and to define the learning curves. methods: patients with benign and malignant periampullary lesion underwent hlapd by a single surgeon between july and may were retrospectively reviewed. the clinicopathologic variables were prospectively collected and analyzed. the learning curve for hlapd was assessed using cumulative sum (cusum) and risk-adjusted cusum (ra-cusum) methods. results: the most common histopathology was pancreatic ductal adenocarcinoma (n= , . %), followed by intraductal papillary mucinous neoplasms (n= , . %), ampulla of vater cancer (n= , . %), and common bile duct cancer (n= , . %). the median operation time was min (range, - min) and the median estimated blood loss was ml. based on the cusum and the ra-cusum analyses, the learning curve for hlapd was grouped into four phases: phase i was the initial learning period (cases - ), phase ii was the technical stabilizing period (cases - ), phase iii was the second learning period (cases - ) and phase iv represented the second stabilizing period (cases - ). there was a statistical difference in terms of surgical indication between phase ii and iii (p= . ). conclusions: hlapd is a technically feasible and safe procedure in selected patients. this procedure has benefits of both open and minimally invasive procedure, and could be a stepping-stone for transition from open to purely minimally invasive pancreaticoduodenectomy. in silico investigation of the background: wilson's disease is a rare autosomal recessive genetic disorder of copper metabolism, which is characterized by hepatic and neurological disease. the gene atp b (on chromosome ) leads to wilson's disease is highly expressed in the liver, kidney, and placenta and encodes a transmembrane protein atpase (atp b), which functions as a copper-dependent p-type atpase. methods: here, the rare codons of atp b gene and their location in the structure of atp b protein was studied with rare codon calculator (racc) (http://nihserver.mbi.ucla.edu/racc/), atgme (http://atgme.org/), latcom (http://structure.biol.ucy.ac.cy/latcom.html) and sherlocc program (http://bcb.med.usherbrooke.ca/sherlocc.php). racc server identified arg, leu, ile, and pro codons as rare codons. results: results showed that cyp a gene have single rare codons of arg. additionally, racc detected two rare codons of leu, single rare codons of ile and rare codon of pro. atp b gene analysis in minmax and sliding_window algorithm resulted in identification of and rare codon clusters, which shows the difference features of these algorithms in detection of rcc. analyzing the d model of atp b protein show that arg residue constitute hydrogen bonds with glu and glu that with mutation of this residue to ser this hydrogen bonds were disrupted and may interfere in the proper folding of this protein. moreover, the side chain of arg don't forms any bond with others residues that with mutation to thr form new hydrogen bond with the side chain of arg . these addition and deletion of hydrogen bonds effects on the folding mechanism of atp b protein and interfere with the proper function of the atp b position. his forms the hydrogen bonds with the his and it seems that this hydrogen bond close together two region of this protein and it seems that has a critical role in the final folding of atp b protein. conclusions: computational study of diseases such as wilson's disease and involved genes (atp b) help us in understanding of disease's physiopathology and finding new approaches for detection and treatment. pancreatic stump leak and fistula formation are significant causes of morbidity in patients undergoing distal pancreatectomy (dp), with incidence of % to as high as % in a large systematic review. we present a case of a year old female, four months status post distal pancreatectomy and splenectomy for pseudopapillary neoplasm of pancreatic tail. patient presented to our institution with day history of left upper quadrant pain and general malaise. differential diagnosis on admission was abdominal wall abscess vs incarcerated incisional hernia. physical exam was positive for severe tenderness to palpation over a * cm cm non reducible mass in left upper quadrant with surrounding skin erythema. patient underwent a diagnostic laparoscopy and intraoperative findings revealed extensive adhesions to the anterior abdominal wall and a loop of small bowel was found adhered to the previous incision site in left upper quadrant. upon further dissection we entered a large cm cavity with saponified caseous material. the saponified material and thick tan fluid were evacuated into an endocatch bag and two large bore jackson pratt drains were left within the cavity. further examination showed that the small intestine was normal with no signs of obstruction or ischemia. fluid studies and cultures were sent and showed yeast like organisms and negative for acid fast bacillus. we report an unusual presentation of a distal pancreatectomy stump leak in the formation of an intra-abdominal saponified fluid collection four months after the primary procedure. given the high incidence of pancreatic stump leak and fistula formation after distal pancreatectomy, much effort has been made to identify factors associated with higher incidence of leaks and their usual and unusual presentations, which will be reviewed in this report. initial concerns regarding healthy donor's safety and graft integrity, need for acquiring surgical expertise in both laparoscopic liver surgery and living donor transplantation (ldlt) have delayed the development of laparoscopic donor hepatectomy in adult-to-adult ldlt. however, decreased blood loss, less postoperative pain, shorter length of stay in hospital, and excellent cosmetic outcome have well been validated as the advantage of laparoscopic hepatectomy. hence, the safety and feasibility for laparoscopic donor should be further investigated. we present initial experiences and safety for totally laparoscopic living donor right hepatectomy. in cases who received elective living donor right hepatectomy for adult-to-adult ldlt, totally laparoscopic approach was applied from may up to august . the anatomical variation of portal vein was not considered as an exclusion criteria, but all donors were with type i portal vein variation. the bile duct anomaly was preoperatively evaluated with magnetic resonance cholangiopancreatography (mrcp) and was never excluded for totally laparoscopic approach. d conventional rigid º rigid laparoscopic system was used in cases and the remaining cases used d flexible laparoscopic system. in about %, hepatic duct anomalies (type , a, b) were identified. the operation time was from hours to hours. and the time for the graft removal was within minutes. the hepatic duct transection was performed under operative cholangiography via a cystic duct and the patency of left hepatic duct was also confirmed by operative cholangiography. however, during postoperative period, bile leakage was identified in only case and resolved after the biliary stent insertion by ercp. during operation, there was no transfusion and the inflow control like pringle maneuver was not used at all. v or v were reconstructed in cases and large right inferior hepatic vein was prepared for anastomosis in cases. all grafts were removed through the suprapubic transverse incision. most donors were discharged at days after hepatectomy. during the short-term follow-up period in the donors except this case, complications were not identified. conclusively, totally laparoscopic right donor hepatectomy in elective adult-to-adult ldlt can be initially attempted after enough experiences of laparoscopic hepatectomy and ldlt. however, the true benefits of totally laparoscopic living donor right hepatectomy should be fully assessed through various experiences from multi-institutes. background: the role of neoadjuvent chemotherapy on the treatment of pancreatic cancer remains widely controversial. studies have evaluated its effect on resectability and survival; however, few have studied the consequence of neoadjuvent therapy on surgical outcomes and complications. methods and procedures: a retrospective analysis was performed utilizing the targeted pancreas module of the national surgical quality improvement project (nsqip) for patients undergoing pancreaticoduodenectomy. neoadjuvent therapy was defined by chemotherapy and/or radiation in the -days before surgery. patient demographics, operative characteristics, and -day outcomes were compared amongst patients undergoing neoadjuvent chemotherapy, radiation, chemoradiation, and no neoadjuvent therapy. both univariable and multivariable analysis were completed. results: pancreaticoduodenectomy was completed in , patients. , patients had no neoadjuvent therapy; underwent both chemotherapy and radiation; underwent chemotherapy alone, and underwent radiation alone. there were no differences in demographics or comorbidities. no difference in -day mortality was found; however pancreatic fistula formation was affected by neoadjuvent therapy. neoadjuvant radiation increased fistula formation (or: . , % ci: . - . ) while neoadjuvent chemotherapy (or: . , % ci: . - . ) was protective. conclusion: neoadjuvent therapy significantly impacts surgical outcomes following pancreaticoduodenectomy. given that pancreatic fistula formation can delay post-operative chemotherapy, it may be reasonable to refrain from neoadjuvent radiation therapy for patients with resectable and borderlineresectable disease. the influence of thickest background: the use of stapling devices for distal pancreatectomy remains controversial, due to concerns about the development of postoperative pancreatic ?stula (popf). pancreas thickness might be associated with popf, but suitable thickness of stapler remains also inconclusive in view of reducing popf. methods: we routinely use thickest endo gia™ reloads with tri-staple™ (covidien, north haven, ct) for pancreas closure during laparoscopic left side pancreatectomy (lp) since . we compared short term surgical results of the consecutive ten patients underwent lp using new stapler (ns) and patients with lp using other type of stapler (os) focusing on popf. results: no patients developed clinically relavent (cr)-popf in ns group and two patients ( . %) with os group experienced cr-popf. however, there was no difference of cr-popf between two groups. pancreas thickness on stapling point were not different between two groups ( . mm vs . mm, p= . ). in ns group, patients ( . %) developed a popf, whereas in os group, patients ( . %) developed a popf. there was also no difference of popf between groups. conclusion: the gia™ reloads with the thickest tri-staple™ allows effective prevention of cr-popf after distal pancreatectomy. however, there was no advantage over thinner stapler for lp. introduction: single-incision laparoscopic hepatectomy (silh) has been showed feasible and safe in experienced hands for selected patients with benign or malignant liver diseases. there were only small series reported and most of the procedures were minor liver resections. we herein present our experience of silh during a period of months. methods and procedures: consecutive patients underwent silh which were performed by two experienced laparoscopic surgeons with straight instruments. patient characteristics and surgical outcomes were analyzed by reviewing the medical charts. results: the patient age was . ± . ( - ) years with male predominance ( patients, . %). six patients ( . %) had liver cirrhosis proved by pathologic examinations. nine procedures ( . %) were indicated for malignancy. four major hepatectomies (over two segments) and nine minor ones were performed including seven anatomical resections. the abdominal incisions were para-or trans-umbilical except one which was along the old operative scar at lower midline, while most of them (n= , . %) was within cm in length. inflow control was carried out by either individual hilar dissection or extraglissonian approach instead of pringle maneuver. the operations were all accomplished successfully without additional ports or open conversion. the operative time was . ± . ( - ) min and the estimated blood loss was . ± . ( - ) ml. five ( . %) patients encountered complications and four of them were classified as clavien-dindo grade i. the postoperative length of hospital stay was . ± . ( - ) days. there was no mortality. conclusion: silh can be performed safely and efficaciously for selected patients with benign and malignant liver diseases including cirrhosis. not only minor but also major liver resections are feasible. this innovative procedure provides low postoperative pain and fast recovery. before adopting this demanding technique, surgeons should be familiar with both single-incision laparoscopic surgery and laparoscopic hepatectomy. better outcomes after the learning curve could be anticipated. background: laparoscopic distal panreatectomy (ldp) has been replacing the open procedure for benign or malignant diseases of the pancreas. however, it is often difficult to apply ldp for pancreatic ductal adenocarcinoma (pdac) because its aggressive invasion to adjacent organs or major vessels. objectives: the objective of this study was to report our experiences for laparoscopic extended pancreatectomy with en-bloc resection of adjacent organs or major vessels for left-sided pdac. methods: we reviewed data for all consecutive patients undergoing ldp for left-sided pdac at asan medical center (seoul, south korea) between april and december . the patients who underwent laparoscopic extended panreatectomy with en-bloc resection of adjacent organs or major vessels were included in analyses. results: of total patients, underwent laparoscopic extended pancreatectomy. there were male and female patients with a median age of . years. resected adjacent organs or vessels were as following: stomach in , duodenum in , colon in , kidney in , superior mesenteric vein in , and celiac axis in . median operative duration was minutes, and median length of hospital stay was days. pathological reports revealed the following: a median tumor size of . cm, the tumor differentiation (well differentiated in , moderately differentiated in , and poorly differentiated in ), t stages (t in , t in , and t in ) , and n stages (n in and n in ). r resection was achieved in patients, and most r resection were tangential retroperitoneal margins. postoperatively, clinically relevant postoperative pancreatic fistula was occured in patients, and there was no -day mortality. median overall survival was . months and year survival rate was . %. conclusions: although laparoscopic surgery has limitations in treating extensive diseases, some selected patients can be applicable for laparoscopic extended pancreatectomy with acceptable complication and survival rates. who underwent hepatic resection was included. these patients were divided into llr or olr. demographics, tumor characteristics, recurrence rates and over-all survival were compared between the groups. results: patients were included and grouped into llr (n= ) and olr (n= ). the average tumor number was ± for both groups, while the mean tumor size was . cm and . cm for the llr and olr group, respectively. when compared with olr, llr had lower post-operative complication rates ( . % vs . %, p= . ) and shorter hospital stay ( vs days, p= . ), although the difference was not statistically significant. overall, recurrence-free and disease-free survival was comparable between llr and olr. introduction: single port surgery has been described since with cholecystectomy, colectomy, gastrectomy, and others. nevertheless, few cases are still reported in field of hbp surgery. herein, we report single port pancreatic surgery developed from our previous experience. we had started single port surgery in , since then we have done more than cases of single port surgery using surgical glove port including cholecystectomy, appendectomy, and colectomy. because we consider this experience should develop to pancreatic surgery, cases of single port staging laparoscopy for potentially resectable and borderline resectable pancreatic cancer and cases of single port plus one port distal pancreatectomy (spop-dp) have been done in our institution. single port staging laparoscopy for pancreatic cancer. resectability was proved in ( %) out of patients while patents had unresectale factor such as small liver and peritoneal metastases that was not able to detect pre-operatively. the length of hospital days were . ± . days and the days to chemotherapy were . ± . days. single port plus one port distal pancreatectomy (spop-dp) spop-dp starts with . cm skin incision on umbilicus. subsequently, a wound retractor is installed at umbilical wound. then, a non-powdered surgical glove ( . inches) is put on the wound retractor through which three -mm slim trocars and one -mm trocar are inserted via each finger tips. a semi-flexible laparoscopic camera is inserted via the middle finger port. -mm port is used when laparoscopic us, mechanical stapler, endo intestinal clip or retrieval bag were needed. an additional -mm port is inserted at left subcostal lesion mainly used for surgeon's right hand instrument. gastric posterior wall is fixed to abdominal wall by suture instead of manual retraction. pre-compression before transection of the pancreas was done using endo intestinal clip before firing. discussion: as we have seen in these two decades, surgery has dramatically been changed by laparoscopic surgery or robotic surgery. nevertheless, because of technical difficulty and relatively high post-operative complication rate, introduction of reduced port surgery to hbp surgery has just started. spop-dp using endo intestinal clip, glove port and gastric wall hanging method is feasible. but its advantage is not clear so far, multicenter rct is highly desired to clear the benefit of reduced port surgery for pancreas. introduction: scoring systems (ss) are an essential pillar of care in acute pancreatitis (ap) management. we compared six ss (acute physiology and chronic health examination (apache-ii), bedside index for severity in ap (bisap), glasgow score, harmless ap score (haps), ranson's score and sequential organ failure assessment (sofa) score) for their utility in predicting severity, intensive care unit (icu) admission and mortality. methods: ap patients treated between july and september were studied retrospectively. demographic profile, clinical presentation and discharge outcomes were recorded. predictive accuracy of six ss was assessed using areas under receiver-operative curve (auc) with pairwise comparisons. results: patients were treated for ap. twenty-two ( . %) patients were excluded for insufficient data. / ( . %) were male and mean age was . ( - ) years. most common aetiology was gallstones ( . %). mean length of stay was . ( - ) days. ( . %) patients had severe ap, ( . %) required icu admission and ( . %) died. table below shows positive predictive value (ppv), negative predictive value (npv) and auc of six ss in predicting outcomes. pairwise comparisons revealed ranson's (p. ) and sofa (p. ) scores were superior than other ss in predicting all three outcomes. auc of sofa was greater than ranson's score in predicting severity (p. ), but similar in predicting icu admission (p= . ) and mortality (p = . ). conclusion: sofa score is superior to classical ss in predicting severity, icu admission, and mortality in ap. introduction: necrotizing pancreatitis is often a devastating sequelae of acute pancreatitis. historically several approaches have been described with variable outcome. open necrosectomy is associated with higher morbidity ( %) and mortality ( %). endoscopic necrosectomy often is tolerated well but associated with stent migration and multiple procedures. video-assisted retroperitoneal debridement is tolerated well but associated with severe bleeding if adjacent blood vessels are injured during the procedure leading to severe complications. methods: in our series, we perform a step up approach by involvement of a multidisciplinary group consisting of general surgeons, gastroenterologists, infectious disease physicians, critical care internalist, interventional radiologist and nutritional services to formulate a management plan. the necrotized pancreas is initially drained with an ir guided drain, fluid cultures sent for microbiology and treatment with appropriate antibiotics if deemed necessary. the drain is gradually upsized to a fr sized drain to form a well-defined tract for surgical debridement; a preoperative ct scan of the abdomen with iv contrast to access the location and proximity of the vasculature around the necrotized pancreas. a collaboration with the interventional radiologist to discuss possible ir embolization of splenic artery prior to surgical debridement. the patient would then undergo video assisted retroperitoneal pancreatic necrosectomy and a sump drain left in-situ at the pancreatic fossa. post-operative management in the surgical icu would be lead by the critical care internalist. results: three patients were managed by this multidisciplinary approach with excellent outcomes. one patient underwent preoperative ir embolization followed by surgical debridement; second patient underwent embolization immediately following debridement; one patient did not require any embolization but had ir on standby if needed to intervene. post-operatively all three patients recovered well. they all were tolerating good oral intake and were discharged to rehabilitation facilities. conclusion: our preliminary experience demonstrates that an early multidisciplinary plan by various subspecialties can result in a pragmatic and successful approach to this potentially catastrophic condition. introduction: liver resection with preservation of as much liver parenchyma as possible is called parenchymal sparing hepatectomy (psh). psh has been shown to improve overall survival by increasing the re-resection rate in patients with colorectal liver metastases (crlm) and recurrence. the caudal-cranial perspective in laparoscopy makes the cranial segments ( , a, , and ) more difficult to access. the objective of this systematic review is to analyze feasibility, safety, morbidity, and oncologic outcomes of laparoscopic psh. methods: a systematic review of the literature was performed. medline/pubmed, scopus, and cochrane databases were searched. a search strategy was published with the prospero registry. a systematic review was conducted on all cases reported, they were categorized by area of resection and quantitative meta-analysis of operative time, blood loss, length of hospital stay, complications, and r resection was performed. results: of the studies screened for relevance, studies were selected. because interventions or endpoints were noncontributory or reporting incomplete, were excluded. only publications remained, reporting data from patients who underwent laparoscopic psh. the highest oxford evidence level was b and selective reporting bias was common due to single center and noncontrolled reports. among them, ( . %) resections were in the cranial segments ( . %), a ( . %), ( %), and ( . %), which previously would have required laparoscopic hemi-hepatectomies or sectorectomies. the most common tumor type was crlm ( %) and the second most common tumor type was hepatocellular carcinoma ( %). feasibility of laparoscopic psh was %, conversion rate was %, and complications were seen in % of cases. no perioperative mortality was reported. no standardized reporting format for complications was used across studies. meta-analysis revealed a weighted average operating time of minutes, estimated blood loss of cc, and length of stay of days. r resections were achieved in % of cases. conclusion: laparoscopic psh of difficult to reach liver tumors are feasible with acceptable conversion and complication rate, but relatively long operating times and relatively high blood loss. in future studies, data on long term survival and specific tumor type recurrence should be reported and bias reduced. yangseok koh , eun-kyu park , hee-joon kim , young-hoe hur , chol-kyoon cho ; chonnam national university hwasun hospital, chonnam national university hospital purpose: laparoscopic surgery has become the mainstream surgical operation due to its stability and feasibility. even for liver surgery, the laparoscopic approach has become an integral procedure. according to the recent international consensus meeting on laparoscopic liver surgery, laparoscopic left lateral sectionectomy ( conclusion: this study showed that laparoscopic lls is safe and feasible, because it involves less blood loss and a shorter hospital stay. for left lateral lesions, laparoscopic lls might be the first option to be considered. keywords: laparoscopy, left lateral sectionectomy. outcome analysis of pure laparoscopic hepatectomy for hcc and cirrhosis by icg immunofluorescence in.-a propensity score analysis introduction: in laparoscopic hepatectomy, the surgeon cannot use their hand to palpate the liver lesion and estimate margin of resection. the use of icg immunofluorescence technique can show up the liver tumour and has the potential to facilitate a throughout assessment during the operation. method: between and , there were patients undergone pure laparoscopic liver resection for hcc in our hospital. patients had undergone surgery by the conventional laparoscopic approach. patients had laparoscopic hepatectomy with additional icg immunofluorescence augmented technique. the surgical outcome was compared with propensity score analysis in a ratio of : . result: patients had icg immunofluorescence assisted laparoscopic hepatectomy (group ). patients using conventional laparoscopic liver resection with propensity-matched were selected for comparison (group ). the median operation time was minutes vs minutes p= . , the median blood loss was ml vs ml (p= . ). additional tumours were identified by icg technique. patients had suspicious lesion picked up by icg technique but proven to be benign pathology on frozen section examination. the sensitivity of tumour detection by group was %. % r resection was achieved in group and group respectively. hospital stay was days vs days (p= . ), post-operative complication was ( %) vs ( . %) (p= . ) none of the patient developed icg related complication. conclusion: in the current study, the new technique showed equally good short-term outcome when compared with conventional laparoscopic hepatectomy. icg immunofluorescence augmented reality is a promising technique that might facilitate easier identification tumour during laparoscopic hepatectomy. surg endosc ( ) :s -s taking the training wheels off: transitioning from robotic assisted to total laparoscopic whipple introduction: there is a substantial learning curve to performing minimally invasive pancreatoduodenectomy (mis-pd) for surgeons who are trained in open pd. the learning curve to transition from robotic assisted pd (rapd) to total laparoscopic pd (tlpd) is not well established. methods: mis-pds performed between january and june performed by sc as a surgeon or co-surgeon were included for analysis. mis-pds were performed using a robotic assisted technique prior to august , and tlpds were performed subsequently. rapds performed prior to were excluded to limit the comparison to rapds after the initial learning curve. demographics, clinical and pathologic outcomes, operative and post-operative outcomes were compared. results: a total of rapds and tlpds were scheduled during the study period. there was no statistically significant difference in age, body mass index, or prior abdominal surgery. median time from initial clinic consultation to surgery was days for the rapd group versus days in the tlpd group (p= . ). conversion to laparotomy was required in of patients ( there were no operative complications or mortality. the mean hospital stay was ± . hours. there was no postoperative jaundice, bile leak, intra-abdominal collections or mortality. conclusion: when surgery is indicated for difficult acute calculous cholecystitis, laparoscopic subtotal cholecystectomy with control of the cystic duct is safe with excellent outcomes. however, if the critical view of safety can't be achieved due to obscured anatomy at calot's triangle, conversion to open surgery or cholecystostomy must be performed to prevent bile duct injury. scott revell, md , joshua parreco , rishi rattan, md , alvaro castillo, md ; u. miami -jfk gme consortium, university of miami, miller school of medicine introduction: over the last two decades the increasing incidence of benign liver tumors has led to the expanded need for clinicians to make therapeutic decisions regarding the utilization of open, minimally invasive and ablative techniques. the purpose of this study was to compare outcomes of the management of benign liver disease based on operative approach and pathology. methods: patients aged years or older who underwent liver surgery for benign liver tumors from to were identified in the nationwide readmissions database. patients were compared based on liver pathology, resection versus ablation, and an open versus laparoscopic/robotic approach. the outcomes of interest were in-hospital mortality, prolonged length of stay (los) [ days, and readmission within -days. univariable analysis was performed for these outcomes and multivariable logistic regression was performed using the variables with a p-value . on univariable analysis. results were weighted for national estimates. results: there were , patients undergoing surgery for benign hepatic tumors in the us during the study period. the most common pathology was benign neoplasm ( . %) followed by hemangioma ( . %), and congenital cystic disease ( . %). resection alone was performed in . %, ablation alone in . %, and resection with ablation in . %. a laparoscopic/robotic approach was used in . % of cases. the overall mortality rate was . %, a prolonged los was found in . %, and readmission within days occurred in . %. an increased risk for mortality was found with hemangioma (or . , p= . ) and congenital cystic disease (or . , p= . ). resection with ablation was associated with an increased risk of prolonged los (or . , p. ), while a laparoscopic/robotic approach was a protective factor for prolonged los (or . , p. ). patients treated with ablation alone were at decreased risk for readmission (or . , p. ). omar m ghanem, md , desmond huynh, md , tomasz rogula, md ; mosaic life care, cedars sinai, introduction: laparoscopic sleeve gastrectomy is the most commonly weight loss procedures performed worldwide. as such, there is great diversity in the techniques utilized. this study aims to identify and categorize the differences in techniques and assess the need for guidelines in this field. case description: surgeons were surveyed on the techniques they employ on biweekly basis using the international bariatric club facebook group. the survey included sleeve staple line reinforcement, preoperative work up, intraoperative hiatal dissection, bougie size, distance from pylorus to distal staple line, and intraoperative leak testing. surveys were conducted between may and july . each survey was active for weeks after which data was collected. participants were required to select a single answer per question. discussion: when surveyed on staple line reinforcement (n= ), surgeons used no reinforcement, over-sewed, buttressed, clipped as necessary, over-sewed as necessary. for preoperative work up (n= ), utilized routine endoscopy, routinely obtained upper gi series, routinely obtained both endoscopy and upper gi, and employed endoscopy or upper gi series only in patients who were symptomatic. for hiatal dissection (n= ), surgeons dissected the hiatus routinely, dissected only when obvious hernias intraoperatively, dissected only if the hernia was detected on preoperative work up, and dissected in the setting of gerd symptoms. for sleeve caliber sizing (n= ), bougie \ f was used by surgeon, bougie size f, f, f were utilized by , bougie size f and f were utilized by , bougie[ f were used by , and gastroscopes ( f) were used by . with regards to distance from pylorus to where the sleeve staple line was initiated (n= ), participants started \ cm away from pylorus, between and cm, and started [ cm from pylorus. finally, for preferred intraoperative leak test during sleeve (n= ), methylene blue was used by surgeons, air leak test by , used both, and opted for none. conclusion: this study characterizes the wide varieties in the techniques used during sleeve gastrectomy. a great number of variations exist in every parameter surveyed; however, there is little evidence comparing the effectiveness and safety of these variations. in this setting, further randomized controlled trials are necessary and should be used to construct guidelines to best optimize outcomes in this extremely common and necessary operation. yen-yi juo, md, mph, yas sanaiha, md, yijun chen, md, erik dutson, md; ucla introduction: bariatric surgeries are commonly performed in accredited centers of excellence, but no consensus exists regarding the optimal readmission destination when complications occurred. our study aims to examine the impact of care fragmentation on post-operative outcome and evaluate its causes and consequences among patients undergoing -day readmission after bariatric surgery. methods: the metabolic and bariatric surgery accreditation and quality improvement program (mbsaqip) database was used to identify patients who experienced -day unplanned readmission following bariatric surgery. non-index readmission was defined as any readmission occurring at a hospital other than the one where initial surgery was performed. primary outcome was -day mortality after surgery. logistic regressions were used to identify risk factors for nonindex readmission and to adjust for confounders in the association between non-index readmission and -day mortality. results: a total of , patients were identified as experiencing -day unplanned readmission following bariatric surgery, among whom ( . %) were non-index readmissions. occurrence of postoperative complication during initial hospitalization was the most significant risk factor for non-index readmission (or . , % ci . - . , p= . ) in our multivariate logistic regression. the three most common reasons for readmission were similar within the two comparison groups, including nausea/vomit, abdominal pain and anastomotic leakage. similar proportion of patients underwent reoperation among the two comparison groups ( . vs . %, p= . ). even after adjusting for occurrence of complications, being readmitted to a non-index facility was still associated with a . -fold odds of -day mortality ( % ci . - . , p\. ). conclusion: non-index readmission significantly increases the risk of -day mortality following bariatric surgery. patients were more likely to visit a non-index facility if complications occurred during their initial hospitalization. further patient education is required to re-inforce the importance of continuity-of-care during management of bariatric complications and guide patient's decision making in choosing readmission destinations. introduction: sleeve gastrectomy has become the most performed bariatric surgery. removing part of the stomach causes weight loss by restricting food intake and regulating the production of incretins, particularly ghrelin. however, prognostic factors to weight loss after sleeve gastrectomy have been difficult to find. the goal of this research was to study the correlation between the volume of resected stomach and weight loss. methods and procedures: volume of resected stomach of patients undergoing sleeve gastrectomy was measured. a standard laparoscopic technique was used. calibration was performed tightly around a fr bougie, and stapling started - cm from the pylorus. the standardized technique for measurement involved insufflation with a g catheter with saline solution to a pressure of cm h o immediately after removal of the specimen. resected stomach's volume, gender, age, bmi, height and % of total weight loss (%twl) at months and year were prospectively recorded. correlation between variables was analyzed with pearson's test and linear regression models. conclusion: removed stomach was larger on men than women and its size slightly correlated to height. however, volume of resected stomach did not seem to have an incidence on short termweight loss. gastric size should not be considered as a prognostic factor for weight loss in patients undergoing sleeve gastrectomy. revisional bariatric surgery after initial laparoscopic sleeve gastrectomy: what to choose salman alsabah, eliana al haddad, ahmad almulla, khaled alenezi, shehab akrouf, waleed buhamid, mohannad alhaddad, saud al-subaie; amiri hospital introduction: bariatric surgery has been shown to produce the most predictable weight loss results, with laparoscopic sleeve gastrectomy (lsg) being the most performed procedure as of . however, inadequate weight-loss may present the need for a revisional procedure. the aim of this study is to compare the efficacy of laparoscopic re-sleeve gastrectomy (lrsg), laparoscopic roux-en-y gastric bypass (lrygb) and gastric mini-bypass surgery (mgbp) in attaining successful weight loss following initial lsg. methods: a retrospective analysis was performed on all patients who underwent lsg at amiri and royale hayat hospital, kuwait from to . a list was obtained of those who underwent revisional bariatric surgery after initial lsg, and their demographics were analyzed. introduction: the aim of this study is to identify potential risk factors or early indicators, specifically related to perioperative blood pressure, and its association with perioperative hemorrhage in the bariatric population. laparoscopic bariatric surgery in the united states has been steadily increasing over the past several years. between and , the annual number of cases has increased by %. although rare, hemorrhagic complications (hc) occur at a rate of - % and can lead to significant morbidity and mortality. by identifying factors which may place a patient at higher chance of hc, surgeons can potentially mitigate those risks. these modifications could reduce morbidity and limit the requirement of transfusions or reoperations. methods and procedures: a retrospective case-control series was performed to include all patients who underwent either laparoscopic sleeve gastrectomy (sg) or laparoscopic roux-en-y gastric bypass (gb) in at a single bariatric center of excellence. a total of patients were identified with perioperative hc. each patient was matched : for procedure, body mass index, and medical comorbidities. peak systolic, diastolic, and mean arterial pressures were compared between groups at time of admission, intraoperative, and during remainder of initial hospital stay. welch's t-tests were used for comparison between groups. results: a total of procedures were performed with de novo sg, and de novo gb. revisional bariatric cases were excluded from the study. hc occurred in ( . %) total patients, gs and gb. four patients required operative treatment for hc, were treated laparoscopically and required laparotomy. the mean diastolic pressures at time of arrival on day of surgery was higher in patients who develop hc (p= . ) and mean peak diastolic pressure intraoperatively was lower in patients who develop hc (p= . ). there was no statistical difference in peak systolic or mean arterial pressures throughout the hospital stay. conclusions: bariatric surgical patients with elevated preoperative diastolic blood pressures are at an increased risk of postoperative hc. additionally, decreased peak diastolic blood pressures may be an early indication of an hc in bariatric patients. introduction: bariatric surgery in the adult population is recognized as one of the most effective treatments for obesity and its comorbidities. nonetheless, the safety, efficacy, and substantial outcomes of bariatric surgery in young adults are still not well documented. the aim of our study is to evaluate the safety and efficacy of laparoscopic sleeve gastrectomy (lsg) in young adults (\ years old) versus older adults (≥ years old). methods: we retrospectively reviewed all patients who underwent bariatric surgery at our institution from to. propensity score matching was used in order to balance covariates, matching for common demographics and comorbidities between the younger patient population (\ years old) and the control group ([ years old). all tests were two-tailed and performed at a significant level of . . statistical software r, version . . ( - - ) was used for all analyses. results: of patients, . % (n= ) met our inclusion criteria after matching. we found . % (n= ) patients under years old and . % (n= ) patients greater or equal to years old (control group). we observed that our younger population distribution was predominantly caucasian and female, . % (n= ) and . % (n= ) respectively. the mean age was . ± . years with a preoperative body mass index (bmi) of . ± . kg/m in the younger group compared to . ± . years and a bmi of . ± . kg/m in the control group. diagnosis of diabetes and hypertension were present in . % (n= ) and . % (n= ) of our younger group, respectively. no statistical significance was found when assessing the percentage of bmi loss (% ebmil) at and months follow-up as shown in table . when comparing the % ebmil at months follow-up, the younger group had . % more ebmil than the control group (p= . ). when assessing post-operative complications we observed no statistical significance. conclusions: bariatric surgery is equally effective and safe in young adult population demonstrating a significant better %ebmil at months following bariatric surgery. following prospective studies are needed to elucidate the resolution and behavior of comorbidities in a younger bariatric population. minimally invasive conversion of sleeve gastrectomy to rouxen-y gastric bypass for intractable gastroesophageal reflux disease: short term outcome background: surgical management recommendations for intractable gastroesophageal reflux disease (gerd) after sleeve gastrectomy (sg) remain controversial. this case series demonstrates our experience with treatment of post-operative intractable gerd using minimally invasive conversion of sg to roux-en-y gastric bypass (rygb). patients and methods: this is a retrospective review of a prospective data registry (mbsaqip) from jan through sept . eleven patients, female and male, were evaluated. of the surgeries, were laparoscopic, assisted with xi da vinci robot, and assisted with si da vinci robot. all patients presented with intractable reflux on high dose ppi. three had a history of aspiration pneumonia. ± . %, respectively. one was omitted due to pending results. conclusion: several solutions exist for operative management of intractable gerd after sg including redo-sleeve gastrectomy, combined gastrectomy with fundoplication, conversion to gastric bypass or anti-reflux procedures such as linx. reports remain small in series and require further study to evaluate the consistency of results. we found minimally invasive conversion of sg to rygb is a highly effective and safe option for treatment of intractable gerd. setthasiri pantanakul, chotirot angkurawaranon, ratchamon pinyoteppratarn, poochong timrattana; rajavithi hospital background: obesity is an important health problem affecting more than million people worldwide. esophageal dysmotility is a gastrointestinal pathology associated with obesity; however, its prevalence and characteristics remain unclear. esophageal dysmotilities have a high prevalence among obese patients regardless of gastrointestinal symptoms. objective: to identify the prevalence of esophageal motility disorder in asymptomatic obese patient. materials and methods: prospective study was performed between june and march . a total of of morbid obese patients who visited the bariatric and metabolic clinic at rajavithi hospital (bangkok, thailand) underwent preoperative evaluation with high resolution esophageal manometric test with manoscantm eso (smith medical). tracings were retrospective analysis and reviewed according to chicago classification criteria for esophageal motility disorders. results: among asymptomatic obese participants, twenty five of them were female. the mean age was . ( - ) years old. most of the participants were classified as class three obesity or over. the mean bmi was . kg/m . no hiatal hernia was found and the anatomy of esophagus was normal in all patients. the mean irp was . mmhg. twenty-one patients ( . %) demonstrated high irp over normal limit ([ mmhg) . four patients demonstrated premature contraction (dl\ . second). hypercontractile esophagus was identified in patients and ineffective motility disorder was found in patients. two patients were diagnosed as distal esophageal spasm (des). two patients were compatible with type achalasia and patients ( . %) have esophageal outflow obstruction. none of the patient demonstrate incomplete bolus clearance even high irp or abnormal motility. conclusion: this study reveals a high prevalence of esophageal dysmotility in asymptomatic thai obese patients. the most common abnormality were esophageal outflow obstruction and ineffective motility. the chicago classification of esophageal motility disorder may not suitable among obese population. sitembile lee, ms , chike okolocha , aliu sanni, mdfacs ; philadelphia college of osteopathic medicine ga campus, eastside bariatric and general surgery introduction: roux-en-y gastric bypass (rygb) is the most popular bariatric procedure performed worldwide, accounting for % of all bariatric procedures. however, in patients with a body mass index (bmi) ≥ kg/m (super-super obese) the rygb procedure can be technically challenging. this has led to the adoption of a single-stage treatment such as one anastomosis (mini) gastric bypass (oagb/mgb) in the super-super obese patients. proponents of the oagb/mgb claim the clinical outcomes are comparable to the rygb. the aim of this study is to compare the outcomes of the two procedures by examining the literature. methods: a systematic review was conducted through pubmed to identify relevant studies from to with comparative data on rygb versus oagb/mgb on super-super obese populations. the primary outcome was the percentage excess weight loss (%ewl). other outcomes include operative times, complication rates and length of hospital stay. results were expressed as standard difference in means with standard error. statistical analysis was done using randomeffects meta-analysis to compare the mean value of the two groups (comprehensive meta analysis version . . software; biostat inc., englewood, nj introduction: obesity is becoming more prevalent in patients with inflammatory bowel disease (ibd). the obese body habitus increases the complexity of surgeries that are often needed to treat ibd. some surgeons may delay definitive surgical treatment because of obesity. little data exists on bariatric surgery in the obese patient with ibd. methods: we retrospectively identified patients who had known diagnosis of ibd who underwent bariatric surgery from to . demographics and post-operative outcomes were assessed. results: patients were identified: with ulcerative colitis (uc) and with crohn's disease (cd). of the uc patients, none of the patients had surgery for uc and only one was on a biologic. of the uc patients, had adjustable gastric band (agb), had gastric bypass and had sleeve gastrectomy. one patient with agb had it replaced for slip and subsequently removed for dysphagia. uc preoperative bmi average was . . postoperative bmi was . with excess weight loss (ewl) of %. average follow up was months. of the cd patients, patients had ileocolic resections and one had total proctocolectomy with end ileostomy. one was on remicade and one on mp. of the cd patients, had agb, had gastric bypass and had sleeve gastrectomy. one agb patient had conversion to gastric bypass because of dysphagia and poor weight loss. a second abg patient had band removal because of dysphagia. cd patients' preoperative bmi average was . . postoperative bmi was . with average ewl of %. average follow up was months. overall, agb patients had % ewl, sleeves % and gastric bypass %. two uc patients had post-operative flares, one immediately post op and one month post-operative. four of the band patients had dysphagia, with one replacement, two removals and one conversion to bypass. there were no leaks, intraabdominal infections, fistulas or wound infections. conclusions: uc patients appear to have higher excess weight loss compared to crohn's patients; ewl % compared to % but was not statistically significant. agb had poor results in both uc and cd patients. sleeve gastrectomy and gastric bypass results in effective weight loss for obese patients with ibd. gastric bypass in ibd patient is controversial, but may be appropriate in the right clinical setting. introduction: previous studies suggest that modest preoperative weight loss is associated with improved weight loss following bariatric surgery. however, there remains a need to investigate factors which may successfully predict preoperative weight loss among bariatric patients. methods and procedures: this analysis included patients who underwent laparoscopic roux-en-y gastric bypass (rygb), sleeve gastrectomy, or gastric banding at an academic medical center in california. data were measured at patients' consult and preoperative clinical visits. preoperative weight loss outcomes were categorized as follows: no weight loss, lost weight, or gained weight. associations between categorical sociodemographic and surgical characteristics and preoperative weight loss outcomes were assessed using the chi-square test of association. associations between continuous measures and preoperative weight loss outcomes were assessed using anova. a sub-group analysis was completed among participants who lost weight prior to bariatric surgery. wilcoxon-rank-sum and kruskal-wallis tests were used to evaluate associations between patient characteristics and the number of pounds lost. results: patients (n= , ) were predominately ages - ( %), female ( %), white ( %), and privately insured ( %). patient race was significantly associated with weight loss outcomes (p = . ): whereas % of white patients lost weight prior to surgery, only % of black patients lost preoperative weight. among privately insured patients, % lost weight. in contrast, % of patients insured by medi-cal/medicaid lost weight (p= . ). on average, lower baseline excess body weight was associated with no weight loss. patients who lost preoperative weight (n= , ) were included in the sub-group analysis. male sex (p\. ), black race (p. ), undergoing laparoscopic rygb (p= . ), no previous abdominal surgeries (p= . ), upper tertile baseline weight (p. ), waist circumference (p\. ), percent body fat (p\. ), bmi (p. ), excess body weight (p. ), and systolic blood pressure (p= . ) were associated with more pounds lost. conclusions: this study demonstrates various associations between sociodemographic and clinical patient characteristics and preoperative weight loss. given previous literature indicating the positive relationship between preoperative and postoperative weight loss following bariatric surgery, the results of this study suggest an opportunity to improve preoperative weight loss among specific groups. yen-yi juo, md, mph , usah khrucharoen, md , yijun chen, md , yas sanaiha, md , peyman benharash, md , erik dutson, md ; background: besides rate and extent of weight loss, little is known regarding factors predicting interval cholecystectomy following bariatric surgery, which are important factors in a surgeon's consideration during decision-making regarding whether to perform prophylactic cholecystectomy. in addition, no previous studies have quantified the incremental costs associated with ic. we aim to identify risk factors predicting interval cholecystectomy (ic) following bariatric surgery and quantify its costs. methods: a retrospective cohort study was performed using the national readmission database - . cox proportional hazard analyses were used to identify risk factors for ic. linear regression models were constructed to examine associations between cholecystectomy timing and cumulative hospitalization costs. background: patient-reported outcomes after bariatric surgery are important in understanding the longitudinal effects of surgery. the impact of hospital practices and surgical outcomes on followup rates remains unexplored. objective: to assess the effect of hospital-level practices and -day complication rates on -year follow-up rates of a standardized patient-reported outcomes survey. methods: bariatric surgery program coordinators in a statewide quality improvement collaborative were surveyed in june about their practices for obtaining patient-reported outcomes data one year after surgery. hospitals were ranked based on their follow-up rates between and (accounting for overall performance and improvement). univariate analysis was used to identify hospital practices associated with higher follow-up rates. multivariable regression was used to identify independent associations between -day outcomes and follow-up rates after adjusting for patient factors. results: overall, follow-up rates improved from ( . %± . ) to ( . %± . ) though there was wide variability between hospitals ( . % vs . % in ) . coordinator survey response rate was %. sixty-one percent of all surveyed coordinators perceived that surgeons prioritize high follow-up rates. when asked how long were their patients followed for, % of coordinators noted their programs provided lifelong follow-up. patient reminders about the -year survey were used by % of programs, mostly during clinic visits ( %). most programs ( %) had implemented strategies to improve follow-up rates, such as handing out the survey ( %) during clinic visits. follow-up providers included surgeons ( %), nurse practitioners ( %), and/or registered dietitians ( %). patient disinterest ( %), loss to follow-up ( %), survey length ( %), and lack of staff/ resources ( %) were the factors most commonly perceived as barriers to high follow-up rates. when compared to programs in the bottom quartile of follow-up rates, those in the top quartile were more likely to hand out the survey to patients during clinic visits ( % vs . %; p= . ) and had lower rates of risk-adjusted severe complications ( . % vs . %; p= . ), readmissions ( . % vs . %; p= . ), and reoperations ( . % vs . %; p= . ). conclusions: hospitals vary considerably in their -year follow-up rates when seeking patientreported outcomes data after bariatric surgery. there were also significant differences in programspecific practices for obtaining these data. hospitals with higher -year follow-up rates were more likely to physically hand surveys to patients during a clinic visit and had lower -day severe complication, readmission, and reoperation rates. improved -year patient-reported outcomes follow-up after bariatric surgery may be a proxy for higher quality perioperative care. david merkle , kazim mohommed , danielle r rioux , dilendra weerasinghe, md, facs ; nova southeastern university, herbert wertheim college of medicine, bariatric surgery is gaining popularity not only for its weight loss benefits, but also for its metabolic effects. we present a -year-old female patient with symptoms of neuroglycopenia, occurring -years post roux-en-y gastric bypass surgery. during one of her syncopal episodes, her blood sugar was noted to be mg/dl. continuous glucose monitoring demonstrated post prandial hypoglycemia, averaging episodes per day, with a maximum of episodes in one day. upon further evaluation, the lab results of the hba c, chromogranin a, somatostatin, and urinary sulfonylurea levels were all normal, with the c-peptide level within the upper limit of normal. ct scan of the abdomen and pelvis did not show any obvious masses in the pancreas, and since the chromogranin a level was normal, it lead to the empiric diagnosis of nesidioblastosis by exclusion. we placed the patient initially on medical management which included a carbohydrate restricted diet of g per meal, eating - small meals per day, and taking mg of acarbose three times per day. overall, symptoms have improved, and she has - episodes per month, compared with about episodes per day. we will also present the data with regards to other invasive treatment options, which are available when medical treatment options have failed, such as gastric bypass reversal versus distal gastrectomy. vertical banded gastroplasties (vbgs) were a common bariatric procedure in the s but have largely fallen out of favor due to unsatisfactory weight loss and a relatively high incidence of longterm complications such as dysphagia and severe gastroesophageal reflux disease (gerd). one of the ways to address these undesirable effects is to convert to a roux-en-y gastric bypass (rygb). the aim of this study was to assess the safety and efficacy of vbg-to-rygb conversion. outcomes of vbg revisions performed at an academic center between and were reviewed. of the vbg revisions, gastrogastrostomies were created in two patients, two underwent a planned -stage conversion, and vbgs were converted to rygbs. patients were operated on an average of years after their initial vbg. presenting symptoms were weight regain (n= , . %), dysphagia (n= , . %), or severe gerd (n= , . %). fourteen patients ( %) had a gastric staple line dehiscence. of the vbg to rygb conversions, were laparoscopic, were converted to open, were open, and were robotic-assisted. average operative time and length of hospital stay were . minutes and . days, respectively. within the first months post-operatively, twelve ( %) patients required readmission directly related to surgery, while eight ( %) visited the emergency department. eight patients ( %) required at least one unplanned operation due to complication(s) during the entire follow-up: small bowel obstruction (n= , at -week, -months, and -months), necrosis/leak of remnant stomach requiring remnant gastrectomy (n= ), tracheostomy for prolonged respiratory failure (n= ), bleeding (n= ), anastomotic leak (n= ), and hemothorax requiring vats (n= ). four patients ( %) had a contained perforation that was medically managed and five ( %) developed a gastrojejunal anastomosis stricture requiring endoscopic intervention. one patient ( . %) developed pulmonary embolism. there was no mortality directly related to surgery. complete resolution or improvement of gerd/dysphagia was appreciated in all patients in the short term follow-up. patients who presented with weight regain had a mean bmi loss of . ± . points in the median follow-up time of . months up to a year after conversion to rygb. in summary, reoperative bariatric surgeries after vbgs are complex, requiring longer operative times and length of stay. our study found % risk of severe complications requiring reoperations, compared to the previously cited % in short and long-term complications. conversion of vbg to rygb provides excellent relief of severe gerd and dysphagia and is a viable option for significant weight reduction. introduction: bariatric surgery is a safe and effective treatment for severe obesity and its comorbidities. however, concomitant splenectomy is sometimes required due to uncontrolled bleeding during the surgery. limited literature exists regarding the effects of concurrent splenectomy on outcomes of bariatric surgery. this study aimed to determine these outcomes. methods: adult patients with obesity who underwent primary, elective laparoscopic roux-en-y gastric bypass (lrygb) or laparoscopic sleeve gastrectomy (lsg) with concomitant splenectomy were identified from the metabolic and bariatric surgery accreditation and quality improvement program (mbsaqip, ) and national surgical quality improvement program (nsqip, (nsqip, - datasets. using propensity scores (based on baseline variables), patients who underwent primary bariatric surgery were matched : to a control group (primary lrygb/lsg without concomitant splenectomy) and thirty-day postoperative outcomes were compared. continuous variables and categorical variables were categorized as medians with interquartile range (iqr) and counts with percentages, respectively. background: several previous studies have suggested a correlation between weight loss and age after bariatric surgery. objective: the aim of our study is to further address age as a preoperative factor to determine the amount of weight loss after bariatric surgery. materials and methods: we performed a retrospective analysis of outcomes of a prospectively maintained database of , obese patients who underwent either sleeve gastrectomy (sg) or roux-en-y gastric bypass surgery (rygb) at our hospital between and . we analyzed the -month, -month, and -year postoperative percent total body weight loss (%tbwl) of obese patients who underwent bariatric surgery based on their preoperative age. results: the average age of patients included in the study was years old with a range of - years. an inverse relationship between preoperative age and postoperative weight loss was observed. younger patients achieved a higher % tbwl than older patients at the -month, -month, and -year postoperative follow-up. the average %tbwl for all patients at the -month, -month, and -year postoperative follow-up periods were . %, . %, and . %, respectively. at the -year follow-up, for every decade increase in age (above the average age of ), patients lost % less tbwl. conclusion: in our study, younger patients tend to lose a greater amount of %tbwl than older patients after bariatric surgery. results: patients participated in the survey. the median age was yo (iqr: - ) and . % were females. the following responses were encountered when asked about the importance of surgery-related factors: the study population indicated the following responses regarding expectations from magnetic surgery compared to conventional laparoscopy: there was no significant evidence of different responses by demographic groups. additionally, . % of the population indicated that a surgeon performing magnetic surgery should be more skillful than a surgeon performing conventional laparoscopy. conclusion: this study represents the first report of bariatric patient's perception regarding surgery-related factors. notably, nearly % of the cohort indicated that cosmesis after surgery is an important factor, whereas the responses regarding the rest of the factors were indicated as expected. the bariatric population included in this study had a positive perception of magnetic surgery. furthermore, the population perceived that this technique is associated with better outcomes, better cosmetic results, and higher surgeon dexterity. introduction: although much is known regarding medical outcomes of metabolic surgery, less is known regarding quality of life outcomes. we hypothesized that the collection of patient-reported outcomes (pros) could help us understand quality of life in this patient population. we chose to primarily use patient reported outcomes measurement information system (promis) instruments because of their broad applicability, low cost, and ability to use computer-adapted technology to survey. methods: we implemented the routine collection of pros as part of clinical care in december, . patients were offered tablets in clinic, and were asked to complete the surveys at most of their visits. we used computer-adapted technology to decrease the length of time needed to survey. we collected the following promis instruments: depression, pain interference, physical function, and satisfaction with social roles. we also collected the gerd-hrql, a general health question, and a current health visual analog scale (vas). we retrospectively reviewed our results from december through september . results: our response rate was % over the last year of collection. in total, assessments were completed by patients. the mean scores in our total patient population were as follows: vas , gerd-hrql , general health , depression , pain , physical function , and social roles . for promis instruments, the mean for the national population is , with as the standard deviation. for the depression and pain scores a higher score is worse, while a higher score indicates better quality of life for social roles and physical function. conclusions: routine collection of patient reported outcomes can be implemented in a metabolic surgery clinic. health-related quality of life appears to be decreased in this patient population compared to the general public. further work is ongoing to learn about postoperative trends, as well as differential effects of metabolic procedures. the effect of peri-operative antibiotic drug class on the resolution rate of hypertension after roux-en-y gastric bypass and sleeve gastrectomy. results: in total, rygb and sg were included in our analysis. no significant differences were found between cefazolin and clindamycin regarding hypertension resolution rates after sg. there was a significant difference in the resolution of hypertension after rygb with the use of prophylactic clindamycin or cefazolin. as shown in figure , patients who underwent rygb and received clindamycin had a significantly higher rate of hypertension resolution compared to cefazolin. this effect started at weeks post-operatively ( . % vs . % respectively, p= . ) and persisted up to the -year ( . % vs . % respectively, p= . ). we found no significant differences in patient age, sex, number of pre-operative hypertensive medications, pre-operative bmi, or %bmi change after year to account for the significant effect of antibiotic choice on hypertension resolution. conclusion: this study represents the first clinical report to suggest an impact of the type of antibiotic administered at the time of rygb on co-morbidity resolution, specifically hypertension. future studies will be needed to confirm that the mechanism of action for this novel finding is due to the differing modifications of the gastrointestinal microflora population based on the specific peri-operative antibiotic administered. introduction: laparoscopic adjustable gastric band with plication (lagbp) is a novel bariatric procedure which combines the adjustability of the laparoscopic adjustable gastric band (lagb) with the restrictive nature of the vertical sleeve gastrectomy (vsg). the addition of plication of the stomach to lagb should provide better appetite control, more effective weight loss, and greater weight loss potential. objective: the purpose of the study was to analyze the outcomes of lagbp at months. setting: this is a retrospective analysis from one surgeon at a single private institution. methods: data from all patients who underwent a primary laparoscopic lagbp procedure from december to june were retrospectively analyzed. data collected from each patient included age, gender, weight, body mass index (bmi), and excess weight loss (ewl). results: sixty-six patients underwent lagbp. the mean age and bmi was . ± . years and . ± . kg/m, respectively. all patients were beyond the -month postoperative mark. no patient was lost to follow-up. the patients lost an average of % and . % excess weight loss (ewl) at months ( . % follow-up) and months ( . % follow-up), respectively. also, the patients lost a mean bmi of . kg/m and . kg/m at months and months, respectively. the total number of fills during the study period was , and the mean fill volume was . ± cc. dysphagia was the most common long-term complication. the mortality rate was %. conclusions: lagbp is a relatively safe and effective bariatric procedure. in light of recent studies demonstrating poor outcomes following lagb, lagbp may prove to be the future for patients desiring a bariatric procedure without resection of the stomach. the median interval between (lrygb) and reoperation is months in group a and months in group b. the median percentage of excess weight loss (%ewl) is % vs %, respectively (p= . ). patients % ( in group a) were admitted in an emergency with an acute abdomen pain. ct scan was performed in patients % and has shown signs of occlusion in all cases. the most common symptoms were abdominal pain and vomiting. the surgery was performed by laparoscopy in patients % and by laparotomy or conversion in patients %. in all cases internal hernia was reduced and closed all defects. in only one patient in (group a) small bowel at jja was resected. there was no mortality and one patient had pneumonia with acute respiratory distress which was treated medically. conclusions: the closure of mesenteric defects at (lrygb) by tight non-absorbable continued sutures is recommended because it is associated with a significant reduction in the incidence of internal hernia. introduction: laparoscopic roux-en-y gastric bypass (rygb) is a common and effective form of bariatric weight loss surgery. however, a subset of patients will fail to achieve the expected total body weight loss (tbwl) greater than % after months or experience significant weight regain despite dietary, psychiatric, and behavioral counseling. although alternative procedural interventions exist for operative revision after suboptimal rygb weight loss, laparoscopic adjustable gastric banding (lagb) provides an option with short operative time, low morbidity, and effective results. we have previously demonstrated that short-term ( -month), and mid-term ( -month) weight loss is achievable with lagb for failed rygb. the objective of this study is to report the long term year outcomes of lagb after rygb failure. methods and procedures: a retrospective review of prospectively collected data before and after rygb when available, and before and after revision with lagb was performed. background: saline filled intragastic balloons have become a common outpatient procedure for the treatment of obesity. acute dilation, ischemia and necrosis of the stomach has been described in the medical literature. gastric necrosis from acute gastric dilation is a rare but life-threatening condition, which requires timely diagnosis and management. we present a case of partial gastric ischemia with necrosis hours following placement of a saline filled intragastric balloon. postoperative complaints of bloating, nausea and vomiting are common complaints following placement of saline filled intragastric balloons and can lead to a delay in diagnosis. early diagnosis and management is essential in avoiding this life threatening complication. case report: a year old woman, bmi , comorbid conditions of diabetes mellitus underwent uncomplicated placement of a saline filled intragastric balloon for treatment of obesity. hours after placement the patient complained of cramping and bloating. hours following placement the patient developed vomiting and presented to an emergency room for evaluation. she was found to have blood glucose exceeding and a severely dilated stomach with pneumotosis on ct evaluation. ng tube decompression and icu management of the severe hyperglycemia was initiated. removal of the intragastric balloon was delayed - hours until an appropriate endoscopic retrieval kit could be obtained. endoscopic retrieval was performed without incident and near complete necrosis of the gastric mucosa was noted. the antrum was the only area spared. hours after retrieval a laparoscopic evaluation of the stomach revealed full thickness necross of the entire fundus and greater curve. indocyanine green (icg) fluorescent dye was used to assess vascular integrity of the remaining stomach and to define lines of resection. resection of the greater curvature was performed using icg florescent dye to ensure that the angle of hiss was viable and well perfused. the patient had a full recovery and subtotal gastrectomy was avoided. conclusions: spontaneous gastric distension exacerbated by gastric outlet obstruction following placement of a saline filled intragastric balloon can occur. unrecognized this condition can lead to ischemia, necrosis and perforation of the stomach. appropriate evaluation of patients following placement of intragastric balloons is essential. recognition of this condition can be delayed due to the complaints of cramping, bloating and vomiting which are typical following placement of saline filled intragastric balloons. untreated, gastric ischemia and necrosis can lead to early perforation which is associated with a high mortality rate. introduction: morbid obesity has become a growing health risk in the united states with up to % of americans suffering with obesity. bariatric surgery remains the best treatment for morbid obesity. the recent use of laparoscopic sleeve gastrectomy (lsg) as a single stage procedure has met with great success because of its quick learning curve and minimal postoperative complication rates. however, there are concerns if the lsg is an effective procedure for long-term weight loss. although criticized at first, the mini-gastric bypass (mgb) surgery has become a great option for morbidly obese patients because of the ability to lose weight with minimal post-op complications. the aim of this review is to assess the outcomes of lsg as it compares to mgb for the management of morbid obesity. introduction: we hypothesize that a jejunoileal anastomosis and partial diversion using magnamosis, a novel magnetic compression device, is technically feasible and will improve insulin resistance and metabolic syndrome similarly to patients who underwent bariatric surgery. metabolic surgery has demonstrated improvements in various parameters including insulin resistance, triglyceride levels, and cholesterol. it may be technically feasible to perform a less-invasive operation through partial diversion, and thereby stimulate an increase in incretins from the l-cells of the ileum to glean these benefits. methods and procedures: we performed a laparotomy and jejunoileal partial diversion using magnamosis in five rhesus macaques with induced insulin resistance through dietary modifications. after surgery, weight was monitored and a metabolic laboratory evaluation was performed weekly. timed tests were performed at baseline and again at and weeks postoperatively for triglyceride levels, glp- , insulin, glucose, and bile acids. the primates were followed for weeks prior to euthanasia. results are represented as mean±sem and all p-values were calculated using a two-sample students' t-test. introduction: many studies concerning individuals seeking bariatric surgery indicate a higher prevalence of psychiatric disorder in this population, both before and after surgery, however results are not conclusive. the aim of this study was to investigate changes in psychiatric health after gastric bypass surgery. methods: patients within the catchment area of the department of psychiatry of the south alvsborg hospital, operated with gastric bypass surgery during - were identified through the scandinavian quality registry (soreg). patients files were examined and psychiatric diagnoses and alcohol/drug abuse were recorded preoperatively and with a follow up time of years. results: a total of operated patients were identified. of these patients had been in contact with the psychiatric department before or after surgery. patients had attempted suicide preoperatively, but no attempts were made postoperatively, all women. patients attempted suicide postoperatively without a previous history of suicidal attempts, men woman. four patients with a preoperative history of alcohol abuse were identified, all women. these individuals did not seem to abuse alcohol/drugs postoperatively. postoperatively patients with an alcohol/drug abuse were identified, men, women. none of them had a former history of abuse. of the patient performing suicidal attempts postoperatively, men woman, had a postoperatively emerging alcohol/drug abuse. conclusion: preoperatively known alcohol/drug abuse or suicidal attempts do not seem to predispose for postoperative abusive problems or suicidal behavior. preoperative identification of individuals prone to alcohol/drug abuse or suicidal attempts seems difficult. introduction: in the past, our group has popularized models for gastric bypass, sleeve and gastric imbrication. there are currently no models to predict weight loss following single anastomosis duodenal switch. surgeons who offer this procedure are left to guess based on their limited experience how their patients will do following surgery we have developed a simple office based algorithm to predict weight loss following this procedure. method: patients met the criteria for this study. these patients underwent surgery at a single institution from june to december . non-linear regression analysis was performed to interpolate weight loss at one year. a multilinear regression was run to determine the significant variables. a model was then constructed to predict weight loss after single anastomosis duodenal switch. results: bmi, htn, gender, and the interaction between htn and dm were found to affect weight loss. the model achieved a r value of . and the average error of prediction in the model was . %ewl. conclusion: today too many surgical practices offer procedures tailored to surgeon instead of the needs of the patient. using our models predicting postoperative weight loss can be a straightforward process using easily gathered data. all surgeons should be doing this currently in their own practice to allow patient to choose targeted healthcare interventions based on patient's personal goals. surg endosc ( ) introduction: there is a long-standing practice of testing anastamosis both in upper and lower gi surgery. post-operative leaks in bariatric surgery are an uncommon but serious compilation increasing morbidity and risk of mortality. the present study looks at the practice of performing an intra-operative leak test during roux-en-y gastric bypass (rygb) and sleeve gastrectomy (sg). methods and procedures: the study was divided in two independent phases of six months and months. data was collected from all patients undergoing sg, rygb or revision rygb within those two periods. to confirm the integrity of the staple line all patients underwent a methylene blue and air test intra-operatively. this was followed by a gastrograffin swallow the morning post procedure. results: total number of patients in the study was . there were four positive intraoperative tests. one patient was a primary rygb and three patients were undergoing revision rygb. all were reinforced and subsequent recovery and gastrograffin swallow showed no leak. one revision rygb had an undetected small bowel injury distal to jejuno-jejunostomy that was not identified on intraoperative or next day imaging. we used multivariate statistical analysis to study our population sample and classified the impact of each factor or their combination with the use of principal component analysis. we used systematic clustering to identify subpopulations that have significant differences in statistical distribution. result: the main determinant of total operative time was the surgeon and the level of his assistant. prior surgeries, bmi and smoking history had a statistically significant impact on the laparoscopic time (p value. ). removing the impact of various surgeons, we detected four clusters of patients based on more than patient characteristics. we noticed total or time had two different clusters: one with a standard-deviation of - min while the other had over min. conclusion: this study may have practical implications on improving scheduling. the different comorbidities of these bariatric patients helped to stratify patients into these main cluster groups. better predictability on length of operative procedure can lead to more efficient use of or time and staff, thus ultimately leading to savings for the hospital. in addition, we used automated noninvasive tracking methods to identify phases of bariatric procedures that will allow more accurate estimated or time to efficiently schedule cases. the smart or, which is equipped with multiple noninvasive sensors, allows for error free tracking and monitoring without human interference. objectives: successful outcomes after bariatric surgery (bs) require a comprehensive educational program (cep) focused on post-surgical dietary and lifestyle changes. at our institution, patients must comply with a -week life-after-surgery program prior to surgery. since many patients are not able to participate in-person, an online cep was created to improve accessibility. to evaluate comprehension, a -question test is administered at the last preoperative visit to participants of both classes. the primary objective of this study is to evaluate the effectiveness of online versus inperson cep in terms of comprehension and post-operative weight loss. methods: patients who underwent bs from august -may were retrospectively reviewed at a single institution. all patients who underwent the in-person or online cep, completed the -question test, and had post-operative follow-up for at least months were included. baseline demographic, operative, and weight data were obtained using the electronic medical record. background: body weight loss after bariatric surgery is affected by several factors. diabetes status or preoperative body mass index (bmi) would affect the body weight loss after surgery. age and sexuality may also be the predictor. furthermore, the malabsorptive procedure is considered more effective for body weight loss than the restrictive procedure alone. we investigated the contribution of preoperative background data and procedures to the body weight loss after surgery. methods: this was a multicenter, retrospective study to validate the efficacy of bariatric surgery for morbidly obese patients in japan. patients underwent sleeve gastrectomy (lsg) or lsg with duodenal-jejunal bypass (lsg/djb) in each institution from january to december , and whose bmi was kg/m or more at the first visit were included in this study. we investigated the percent excess body weight loss (%ewl) at months after surgery. univariate and multivariate analyses were done to evaluate the predictive factors of body weight loss. we defined that %ewl more than % as well response (wr background: despite its known safety and efficacy, bariatric surgery is an underutilized treatment for morbid obesity in the united states. objective: our goal was to identify factors associated with failing to proceed with surgery despite being considered an eligible candidate by a bariatric surgery program. methods: this is a retrospective study that includes all patients (n= ) who attended a bariatric surgery informational session (bis) at a single center academic institution in . eligible candidates were identified after clinical evaluation and multidisciplinary candidacy review (mcr). we compared patients who underwent surgery to those who did not (i.e. dropped out) by evaluating patient-specific, insurance-specific, and bariatric surgery program-specific variables. univariate analysis and multivariable regression were performed to identify risk factors associated with failing to undergo surgery among eligible candidates. introduction: the elderly are a special subset of the population due to their limited physiological reserve with aging. revisional bariatric surgery is becoming more common with increase in primary bariatric procedures. data on safety, weight loss, and metabolic effects of revisional bariatric surgery in elderly is limited. the aim of this study was to assess the safety and efficacy of revisional bariatric surgery in the elderly. methods: clinical data of all elderly patients ( years and above) who underwent elective revisional bariatric surgery at an academic institute between and were reviewed. demographic data, perioperative variables, and postoperative outcomes were studied. results: a total of patients were identified with a female predominance ( : ). mean age was ± . years. mean bmi at the time of revisional surgery was . ± . kg/m . the primary indication for revisional surgery included management of postoperative adverse events (n= , . %) and weight recidivism (n= , . %). in patients with postoperative complications, the most common indications for revisional surgery were dysphagia (n= , . %), marginal ulcer (n= , . %), gastric outlet obstruction (n= , . %), and fistula formation (n= , . %). the most common type of revisions included conversion of vertical banded gastroplasty to roux-en-y gastric bypass (rygb, n= ), revision of rygb (n= ), conversion of adjustable gastric banding to sleeve gastrectomy (sg, n= ), and sg to rygb (n= ). two out of seven ( . %) patients with -day postoperative readmissions had serious complications that required reoperation. one of them underwent small bowel resection for ischemia and the other had thoracotomy for hemothorax evacuation developing secondary to a gastropleural fistula. while there was no mortality over the first days postoperatively, two patients died months after surgery due to infectious complications. in the median follow-up time of (interquartile range, - ) months, mean weight and bmi changes of − . kg and − . kg/m were observed. twenty-three ( . %) patients had diabetes at time of revisional surgery. a mean reduction of . mg/dl in fasting blood glucose and . % in glycated hemoglobin were noted between baseline and last follow-up. conclusion: revisional bariatric surgery in elderly is associated with high complication rates. our data indicate that revisional bariatric surgery can potentially alleviate symptoms and resolve complications of primary bariatric surgery. elderly patients should have their risk stratified and weighed against the benefits of surgery. anne-marie carpenter, bs, alexander l ayzengart, md, mph; university of florida introduction: bariatric surgery is the most effective treatment for morbid obesity. of all available procedures, laparoscopic sleeve gastrectomy (lsg) is now the most popular worldwide. common complications of lsg include gastroesophageal reflux, stricture, and staple-line leak. although rare, portomesenteric venous thrombosis (pmvt) and liver retractor-induced injuries are increasingly reported. we present a case of isolated left portal vein thrombus after routine lsg that was likely caused by prolonged compression of left liver lobe by the nathanson retractor. case presentation: a -year-old female with a bmi of and biliary colic due to cholelithiasis underwent lsg with hiatal hernia repair and cholecystectomy. she tolerated the procedure without complication and was discharged home on the following day. on postoperative day , she presented to the emergency department with fever and epigastric pain. contrast ct revealed an isolated filling defect within the proximal left portal vein; abdominal doppler demonstrated an acute thrombus occluding the left portal vein with normal flow in the main and right portal veins. the patient was treated with a -month course of therapeutic anticoagulation with lovenox. a complete hematologic workup did not uncover any hypercoagulable conditions. the patient recovered well and remained asymptomatic at her follow-up visit weeks after operation. discussion: pmvt is a rare surgical complication with multifactorial etiology. in bariatric surgery, evidence suggests lsg elicits more frequent pmvt compared with roux-en-y gastric bypass. a systematic review cited the incidence rate of pmvt as . - % after lsg. the mechanisms are thought to be due to pneumoperitoneum, procoagulant obese state, manipulation of portomesenteric venous system during division of the gastrocolic ligament, and postoperative dehydration. liver retraction is paramount during laparoscopic bariatric surgery to provide adequate visualization of the upper stomach and diaphragmatic hiatus. most methods of liver retraction produce significant pressure on the liver parenchyma by compressing it against the diaphragm. three types of liver injury have been documented in literature: minor congestion, traumatic parenchymal rupture, and delayed liver necrosis. uniquely, we propose an additional type of injury-left portal vein thrombosis due to compression of left liver lobe with the nathanson retractor. conclusion: the case described herein represents the first documented report of isolated left portal vein thrombosis after lsg. this is a unique presentation of retraction-related liver injury causing pmvt by mechanical compression of liver parenchyma. as surgical procedures increase in duration, intermittent release of liver retraction should be performed at regular intervals. introduction: up to % of patients experience internal hernia (ih) after laparoscopic roux-en-y gastric bypass (rygb). studies have shown that antecolic roux limb orientation, and closure of the mesenteric defect reduce, but do not eliminate, the incidence of ih. we hypothesize that despite operative differences, ih occur more frequently in patients who experience significant weight loss. this study aims to determine whether those patients who present with ih following rygb experience greater than % excess body weight loss (ebwl). methods: a retrospective chart of all patients who underwent ih repair following rygb at our institution between sept and sept was performed. all applicable cpt codes to encompass ih repair were reviewed (n= ). patients with ih repair after rygb were identified. results: of the patients, were female. the mean pre-rygb weight was lbs (sd± . ), bmi . kg/m (sd± . ). all procedures but one were performed in an antecolic configuration; the other retrocolic-antegastric. fifteen cases were laparoscopic and two were open; nine had the jejunal mesenteric defect closed, eight did not. the average weight loss from the time of rygbp to ih presentation was . lbs (sd± . ) and %ebwl from rygb to the nadir weight was % (sd± ). when evaluated by t-test, there was no statistical difference in bmi at the time of program initiation, rygb, or ih presentation, as well as number of pounds lost, %ebwl, or time to ih presentation, when comparing patients for whom the mesenteric defect was closed or not. average time from rygb to ih presentation was . years (range - days) . conclusion: in our limited cohort of patients who have presented with internal hernia after rygb, there was an average of % ebwl. this is greater than the average expected %ebwl at our institution and others, suggesting that ih may occur in patients with greater weight loss at a higher frequency. mesenteric defect closure did not appear to have any influence in this limited cohort, suggesting that weight loss is a stronger factor in ih development. we plan a more extensive evaluation in a larger cohort of patients to determine if greater %ebwl is a predictor of ih formation in patients undergoing rygb. introduction: introduction of enhanced recovery after surgery (eras) pathways has led to early recovery and shorter hospital stay after laparoscopic roux-en-y gastric bypass (lrygb) and laparoscopic sleeve gastrectomy (lsg). this study aims to assess feasibility and outcomes of postoperative day (pod) discharge after lrygb and lsg from a national database. methods: patients who underwent elective primary lrygb and lsg and were discharged on pod and were extracted from metabolic and bariatric surgery accreditation and quality improvement program (mbsaqip) dataset. a : propensity score matching was performed between cases with pod vs pod discharge, and the -day outcomes of the propensity-matched cohorts were compared. high risk patients were excluded from the analysis. purpose: the aim of this study was to evaluate a large volume, multi surgeon bariatric surgery center producing the largest sample size to date proving efficacy (% weight loss) and safety of sleeve gastrectomy following band removal in one or two step procedures. methods: all patients undergoing conversion of lagb to lrygb ( ) and lsg ( ) regardless of one step vs two step conversion from january to january were included. a retrospective analysis of our prospectively maintained database was performed to compare outcomes in patients undergoing conversion to lrybg vs lsg after lagb to identify the outcomes. introduction: the purpose of the study was to describe the use of intraoperative indocyanine green (icg) fluorescence angiography to identify the blood supply patterns of the stomach and gastroesophageal junction (gej). we hypothesized that identifying these vascular patterns may help modifying the surgical technique to prevent ischemia-related postoperative leaks. methods: patients underwent laparoscopic sg and were examined intraoperatively with icg fluorescence angiography at an academic center from january to september . prior to the construction of the sg, ml of icg was injected intravenously and pinpoint® technology was used to identify the blood supply of the stomach. afterwards, the sg was created with attention to preserving the identified blood supply to the gej and gastric tube. finally, ml of icg were injected and pinpoint® technology was used again to ensure that all the pertinent blood vessels were preserved. results: patients successfully underwent the procedure with no complications. the following blood supply patterns to the gej were found: the incidence of overall accessory blood supply to the right-side dominant pattern was more common than expected. in about half of the cases where an accessory vessel was found in the gastrohepatic ligament, the blood flow was toward the stomach (and not the liver). furthermore, the incidence of accessory blood supply from the left side was found in % of the cases. % of patients had both the left side accessory and accessory gastric artery pattern. in these particular patients, if a concurrent hiatal hernia repair is performed, these accessory blood supplies are at risk of being injured if care is not taken to preserve them, rendering the gej relatively ischemic. conclusion: icg fluorescence angiography allows determining the major blood supply to the proximal stomach prior to any dissection during sleeve gastrectomy so that an effort can be made to avoid unnecessary injury to these vessels. background: morbid obesity, a common medical concern with significant health risks, has a prevalence of . % among u.s. adults. bariatric surgery provides effective weight loss for morbidly obese patients with improvement in their comorbid conditions. traditionally, routine intraoperative drain placement (idp) and postoperative esophagram (ugis) were thought to identify early postoperative complications. recently, these interventions have been scrutinized for their effectiveness. we hypothesized that idp and postoperative ugis do not alter outcomes in bariatric surgery and only increase hospital length of stay (los). methods: two cohorts, each consisting of patients from either or were analyzed from our institution. in the cohort, all patients had idp and an ugis on postoperative day , prior to starting a clear liquid diet. in the cohort, no patients had idp or ugis, but instead were started on a clear liquid diet on postoperative day , in the absence of vomiting. all patients in each cohort underwent either a laparoscopic sleeve gastrectomy or a roux-en-y gastric bypass. a retrospective study was performed to analyze whether there was a significant difference in postoperative complications, length of stay, and operating room time between these two cohorts. those who underwent t dm remission were less likely to be vdd at all time points. the rates of vdd appear to be slightly higher in rygb at each time points. the rates of macrocytic anemia, microcytic anemia and hypoalbuminemia were low and varied depending on surgical procedure, with no relevant increase following surgery (see figure ). conclusions: vitamin d deficiency is prevalent among diabetic patients with obesity presenting for bariatric surgery. the postoperative management was successful in addressing vdd following surgery; those who experienced t dm remission after surgery were less likely to be vdd. further prospective studies are needed to explore this relationship. surg endosc ( ) :s -s introduction: it is well known that morbid obesity is strongly associated with high blood pressure. cardiovascular risk reduction is a well studied and described result of bariatric surgery. the objective of this study is to quantify hypertension resolution in patients who underwent bariatric surgery at our institution. methods: we retrospectively reviewed all the patients who underwent either laparoscopic sleeve gastrectomy (lsg) or laparoscopic roux en y gastric bypass (lrygb) at our institution between and . we selected those patients who were on antihypertensive medical treatment and had a -month follow-up. hypertension resolution was defined as the interruption of any blood pressure medications within the follow-up period. we compared the patients who had resolution of hypertension (group ) with patients who did not (group ), based on demographics, comorbidities, and outcomes. chi-square and student t-test were used for categorical and continuous variables respectively. results: out of patients, ( . %) patients met the inclusion criteria, out of which, ( . %) had a complete resolution of hypertension within months. the patient population included in group was predominantly female n= patients ( . %), diabetic (n= , %), with a mean bmi of . ± . kg/m , a mean age of . ± . years, and a preoperative systolic blood pressure mean of ± . mmhg. the most common procedure performed was lsg with n= ( %). comparison between group and group based on age, gender, bmi, and diabetes showed no statistically significant difference. estimated bmi loss % at months, type of procedure and % ebmil showed no statistically significant difference between the groups. conclusions: rapid weight loss is associated with a drastic reduction of blood pressure. besides weight loss, we did not identify a clear correlation between risk factors when we compared patients who had resolution of hypertension with patients without resolution. further prospective studies should be done for better understand these findings. the mount sinai hospital, university of chicago introduction: for many patients, hiv has transformed from a life-threatening illness into a manageable chronic disease. reflecting trends in the general population, obesity is increasingly prevalent among hiv-positive patients. surgical intervention has shown the greatest effectiveness in treating obesity. it is unknown, however, whether physician attitudes reflect the changing trends in obesity care for hiv-positive patients. methods and procedures: medical students from the first, second, and fourth years of training were invited to participate in an irb-approved survey, handed out during didactic sessions, which was designed to assess their knowledge and attitudes regarding bariatric surgery in hiv-positive patients. self-reported demographic information of respondents was also collected. the outcome of interest was the proportion of correct responses. univariate and multivariate regression analyses were performed. results: surveys were completed by medical students. demographic covariates included the following: age, sex, race, bmi, and year of training. age, sex, race, and bmi were not statistically significant in the multivariate model. however, in both univariate and multivariate models, each additional year of training was associated with a significant increase in the proportion of correct responses (multivariate model beta coefficient= . , p. ). conclusions: obese and hiv-positive patients suffer from well-documented stigma in health care. these findings suggest that medical training corrects common misperceptions of obese and hivpositive patients, and may lead to a better understanding of the appropriateness of bariatric surgery for hiv patients. whether these attitudes are predictive of referral practices remains to be seen. introduction: obesity is a common problem worldwide with numerous associated comorbidities and is associated with an increased risk of developing some cancers. despite bariatric surgery being associated with a risk reduction for cancer development, some will develop cancer after surgery and little is known about complications which might arise during multimodality cancer treatment. here we report the case of a year-old female who developed an unusual giant marginal ulcer (mu) post laparoscopic roux-en-y-gastric bypass (lrygb) while receiving systemic chemotherapy for an early stage breast cancer. case report: in summary, a year-old female with a preoperative bmi of kg/m had an uncomplicated lrygb one year prior to her presentation. she was a non-smoker, was abstinent of alcohol and did not use nsaids, steroids or other ulcerogenic medications. eight months post procedure with a bmi of . kg/m she was diagnosed and treated with bcs plus slnb for a pt n m er/pr +ve her −ve breast cancer. one week following her third cycle of docetaxel and cyclophosphamide, she presented with two days of melena, small volume hematemesis and abdominal discomfort. the patient was resuscitated with prbc, started on a ppi infusion and had free air ruled out on a cxr. upper endoscopy was complete showing a giant mu at the gastrojejunal anastomosis, biopsies ruled out malignancy and h. pylori. subsequent ct abdomen/pelvis identified contrast extravasation from the anastomosis confirming a free perforation. broad spectrum antibiotics were started and a diagnostic laparoscopy complete. a graham patch repair utilizing omentum and abdominal washout were complete with placement of surgical drains. the patient was supported with parenteral nutrition while npo. diet was advanced after an upper gi series on post operative day showed no ongoing leak. the patient was discharged on post operative day , recovered and although further chemotherapy was discontinued she completed whole breast radiotherapy. conclusion: leaks and hemorrhage are early postoperative complications that are not seen intraoperatively in our experience. furthermore, endoscopy significantly increases mean operative time. routine use should be left to the discretion of the surgeon but should not be considered an essential step of the sleeve gastrectomy. the objective of the study: surgical site infection (ssi) following bariatric surgery contributes to patient morbidity and additional use of health care resources. we investigated whether a ssi quality control initiative in the form of a refined preoperativeantimicrobial protocol affected the rate of ssi following laparoscopic roux-en-y gastric bypass (lrygb). we reviewed all lrygb procedures performed between june and december at a single bariatric surgery centre of excellence. two preoperative antimicrobial protocols were compared. patients undergoing surgery prior to february received g of cefazolin whereas patients undergoing surgery after february , received a new antimicrobial protocol consisting of g cefazolin, mg metronidazole and ml oralchlorhexidine rinse. the primary outcome was day ssi including superficial ssi, deep incisional ssi and organ/space infection as defined by the centre for disease control. clinic charts and provincial electronic medical records were reviewed for emergency department visits, microbiology investigations and physician dictations diagnosing ssi. outcomes were assessed using a students t-test. results: two hundred seventy six patients underwent lrygb of which received the refined antimicrobial protocol and received cefazolin. the refined antimicrobial protocol significantly decreased the rate of deep incisional ssi compared to cefazolin (n= , . % vs n= , . %; p\ . ). the refined antimicrobial protocol resulted in an insignificant overall reduction in the rate of superficial ssi (n= , . % vs n= , . %; p[ . ) and organ/space infection (n= , . % vs n= , . %; p[ . ) respectively. conclusions: a preoperative antimicrobial protocol using cefazolin, metronidazole and chlorhexidine oral rinse appears to reduce the rate of ssi following lrygb. this protocol may be most effective to prevent deep incisional ssi. additional patient cases or alternative study design including a randomized control trial is required to better understand the efficacy of this protocol. background: for many years, the roux-en-y gastric bypass (rygb) was considered a good balance of complications and weight loss. according to a several short-term studies single anastomosis duodenal switch or stomach intestinal pylorus sparing surgery (sips) offers similar to weight loss to rygb with fewer complications and better diabetes resolution. however, no one has substantiated complication and nutritional differences between these two procedures over the midterm. this paper seeks to substantiate previous studies and compare complication and nutritional outcomes between rygb and sips. methods: a retrospective analysis of patients who either had sips or rygb from to . complications were gathered for each patient. nutritional outcomes were measured for each group at , , and years. regression analysis was applied to interpolate each patient's weight at , , , , , , and months. these were then compared with t tests, fisher exact tests, and chi squared tests. results: rygb and sips have statistically similar weight loss at , , , , and months. they statistically differ at and months. at months, there is a trend for weight loss difference. there were only statistical differences in nutritional outcomes between the two procedures with calcium at and years and vitamin d at year. there were statistically significantly more long term major complications, minor complications, reoperations, ulcers, small bowel obstructions, nausea, and vomiting with the rygb than sips. conclusion: with comparable weight loss and nutritional outcomes, sips has fewer short and long-term complications than rygb and better type diabetes resolution rates. introduction: the purpose of this study is to determine the risk factors that contributed to increased postoperative complications, as noted in prior studies within the publicly funded insurance population undergoing bariatric surgery. methods and procedures: data was collected via a retrospective review of the medical records of patients who underwent laparoscopic roux en y gastric bypass or laparoscopic sleeve gastrectomy from to at a single institution. for each patient, data was collected in the following categories: baseline demographics, insurance status, medical comorbidities, immediate complications, re-admissions and associated complications, and follow up out to years. results: a total of patient charts were reviewed, patients were categorized as private insurance and patients were categorized as public insurance. there was no statistically significant difference in mean patient age (private . years vs public years), sex (male:female %: % for both groups), or bmi ( vs ). there was a statistical significance in relationship status in the categories of single ( % vs %), married ( % vs %) or living with a partner ( % vs %), as well as employment status ( % vs %). when comparing comorbid conditions preoperatively there was no difference except for diabetes which was less common in the private insurance group % vs %. readmission rates for complications were significantly different as well at % vs % with public insurance patients having increased complication rates and readmissions. there was no difference in follow up percentages at each time point for the two groups. interestingly postoperative bmi was significantly different in the two groups until year out ( vs ) when the difference disappears. conclusions: our current data set confirms prior research that documented higher complication rates in public insurance patient populations without differences in long term results in regards to weight loss. it also shows that the public insurance group is possibly at higher risk for complications and readmissions postoperatively due to the lack of social support at home given that a much higher percentage of them are single or divorced, and lack employment. it is likely that this lack of support at home prompts more frequent readmissions and associated complications. introduction: gastric bypass has been an acceptable treatment for the morbidly obese patient, with proven efficacy on weight loss and remission of co morbidities, especially diabetes (t dm). laparoscopic sleeve gastrectomy (lsg) is gaining momentum as an alternative procedure for the morbidly obese patient. the aim of this study is to assess the resolution of t dm by examining hba c, bmi, fat %, and % excess weight loss in t dm patients in our lsg patients. methods: we performed a retrospective chart review of t dm patients before and after lsg, analyzing hga c, bmi, % weight loss, fat %, and diabetic medications. data was analyzed by using spss version . paired t-test was applied to see the significance of bmi, weight, fat % and hba c before and after the procedure. introduction: gastroesophageal reflux disease (gerd) is a known risk following laparoscopic sleeve gastrectomy (lsg), with up to % of patients affected by the disease postoperatively. of these patients, an unknown number progress to medically refractory gerd. due to their postsurgical anatomy, these patients have limited options for intervention. while endoluminal therapies are available, surgical revision to roux-en-y gastric bypass (lrygb) has become an accepted revisional treatment. despite this therapeutic option, many payors deny coverage for this treatment. in this study, we report outcomes of revision of lsg to lrygb and difficulties in obtaining insurance approval for the operation. methods: we conducted a retrospective review of all patients who underwent a revisional bariatric operation at a single institution between january and august . we analyzed all patients who underwent conversion of lsg to lrygb. we collected data on -day mortality and morbidities, pre-and postoperative antacid use, and the insurance approval process. results: within the study period, we identified patients undergoing revisional bariatric surgery. seventeen patients had undergone conversion of lsg to lrygb. all of these patients underwent revision due gerd refractory to maximal medical therapy. the average body mass index was kg/m , and our average operative time was minutes. one patient required laparoscopic cholecystectomy within days due to acute cholecystitis, and another patient required reoperation for control of staple line bleeding. there were otherwise no -day morbidities or readmissions. fifty nine percent stopped all antacid medication by six months, and % stopped by months. of the % percent of patient still on proton pump inhibitor therapy, none of those patients complained of reflux symptoms. of non-medicare patients, % were initially denied insurance coverage for revision. only one plan accounted for all initial approvals. twenty five percent of denied patients eventually paid out of pocket, and the remaining % ultimately secured coverage after an appeal process. with no significant differences in mortality or hospital stay. significantly shorter operative times were observed in the adolescent group ( . ± vs . ± , p. ). in univariate analysis blood transfusions and vte rates were significantly lower in the adolescent group but there was no difference after risk-adjusted logistic regression analysis. analysis of readmission data showed lower rates in adolescents compared to young adults ( . % vs . % p= . ). however, adolescents are more frequently readmitted secondary to gallstone disease ( . % vs . %, p. ). the most common reason for readmissions in both groups was nausea and vomiting with fluid/electrolyte depletion, followed by abdominal pain. conclusion: adolescent bariatric surgery is feasible and safe, with outcomes similar to that of young adults. lsg is currently the most common bariatric procedure performed in adolescents which is reasonable given the relative lack of co-morbid conditions within this group. nausea and vomiting are the most common reason of readmission in both groups, but gallstone disease is significantly higher in adolescents, suggesting that this population should be carefully screened for gallbladder disease preoperatively. further studies regarding long-term results are needed to elucidate long-term outcomes, such as the durability of comorbidity resolutions in adolescent patients. introduction: revision bariatric surgery is always considered to be associated with higher complication rates. there is currently controversy in the literature regarding one stage and two stage revisions. methods: the present study is ongoing longitudinal prospective analysis of data of revision surgery in a single unit. the revision surgery was offered after initial failed or complicated gastric band, sleeve gastrectomy and roux-en-y gastric bypass (rygb). results: there were forty-two individuals who had revision bariatric surgery. the age of the cohort of patients ranged from twenty-six to seventy-five years. thirty-three were females and nine males. all patients who were hypertensive or diabetic at the time of their initial bariatric operation had a relapse of their co-morbidity prior to their revision surgery. the two stage revisions patients had their band removed at another facility, had a compilation from the band itself or did not wish for revision surgery initially. of the two failed bypasses one had a large pouch and very short limbs. the other had a gastro-gastric fistula and ultra short limbs. there were no deaths in this study. one patient who underwent one stage revision of a gastric band to bypass had an iatrogenic small bowel injury that required a second operation. amelioration of diabetes and hypertension was seen in all who had relapsed. weight loss was good in all patients except for the those undergoing revision from short limbed to long limbed bypass. conclusion: there is enough evidence that revision surgery is feasible, and can ameliorate metabolic co-morbidities after failed band and sleeve. two staged surgery is not necessarily safer compared to one stage revision. in the present study an inadvertent iatrogenic injury occurred in one stage revision group but is not true reflection of increased complications. the association between preoperative endoscopic esophagitis and post operative gerd in sleeve gastrectomy patients samer elkassem, md; medicine hat regional hospital introduction: gerd is a common complication after sleeve gastrectomy (sg). the purpose of this study is assess the relationship between pre-operative findings of endoscopic esophagitis and postoperative gerd in sg patients. the hypothesis of this study is that patients with pre-op esophagitis are more likely to have gerd post-op than patients with no esophagitis pre-op. methods: a retrospective review of sg patients who had pre-operative endoscopy and followed prospectively for at least one year was preformed. patients were divided into two groups based on pre-op endoscopic findings: those with no findings of esophagitis (ne), and those with endoscopic esophagitis, including barretts (ee). patients were followed for at least one year, and assessed for usage of a proton pump inhibitor (ppi) usage. the two groups were compared using both student t-test and chi square test. results: a total of patients did not have any findings of esophagitis on pre-op endoscopy (ne group), and patients had findings of endoscopic esophigitis (ee). there was no difference in preoperative demographics and post-op weight loss at one year (table i) . follow-up ranged from one to years post-op. the dependency on ppi usage and de novo reflux are shown in table ii . introduction: patients with "super-super obesity", defined as a bmi≥ , are at higher risk of weight-related health problems and might benefit more than others from metabolic and bariatric surgery. however, these benefits need to be weighed against the potential for increased operative and perioperative risks. accurate data regarding these patients is critical to guide procedure choice and informed, shared decision-making. the metabolic and bariatric surgery accreditation and quality improvement program (mbsa-qip) is a national accreditation and quality improvement program, which captures clinically-rich specialty-specific data for the majority of all bariatric operations in the united states. this is the first analysis of the mbsaqip participant use file (puf) focusing on this at-risk subpopulation. introduction: sleeve gastrectomy represents one of the most common surgical procedure used in bariatric surgery. the most feared complication following laparoscopic sleeve gastrectomy is the leak that occurs at the staple line. one method to reduce the risk of leak is the use of reinforcement material at the suture line. in this study, the efficacy of sutures and fibrin glue in the prevention of staple leak has been compared retrospectively. materials and methods: a total of patients undergoing lsg between october and august at the medical faculty of firat university were retrospectively assessed using the hospital database system records. results: there were males ( %) and ( %) females, with a mean age of years (range: - y), and body mass index of kg/m . while no reinforcement material was used in patients ( %) at the suture line, reinforcement sutures or fibrin glue were used in ( %) and ( %) patients, respectively. postoperative leak occurred in patients ( . %), and ( . %) of these had no use of reinforcment material for leak prevention, while additional sutures or fibrin glue had been used in patients, one in each group ( . %). one patient died due to leak and the consequent development of sepsis ( . %). discussion: lsg is increasingly more frequently used in bariatric surgery practice. however, an increase also occurs in the rate of complications. a discrepancy exists in the published literature regarding the benefit of reinforcment the suture line on the risk of leak risk. in our patient series, patients without the use of additional material in the staple line had a significantly increased risk of leak. conclusion: despite some controversy, strong evidence exists on the effectiveness of fibrin glue in the prevention of leaks in patients undergoing laparoscopic sleeve gastrectomy. background: laparoscopic bariatric surgery has been performed safely since . in a persistent search for fewer and smaller scars, single port and acuscopic surgery or even notes have been implemented. the goal of this study is to analyze the safety and feasibility of using a low cost incisionless liver retraction compared to a standard laparoscopic retractor for sleeve gastrectomy. methods and procedures: candidates for sleeve gastrectomy that fulfilled nih criteria for bariatric surgery were selected. those younger than and/or with prior upper-left quadrant surgery were excluded. all patients signed written consent. patients were randomized : to either a standard port technique with a fan-type liver retractor through a mm port (group a); or a port technique with the liver retracted by a polypropylene suture passed through the right crura and retrieved at the epigastrium with the use of a fascia closure needle (group b). all surgeries were performed by the same surgeon. surgery length from insertion of first port to withdrawal of the last was the primary endpoint. anthropometric data, % of pre-surgical total weight loss (%ptwl), visualization of the surgical field, complications inherent to liver retraction and postoperative morbidity were recorded. background: comprehensive web and hospital based preparative patient education allow the morbidly obese patients to understand weight loss surgery, its benefits, the necessity of follow up and the risk of weight regain. while the inhouse seminars provide a face-to-face interaction with the bariatric program staff, the online seminars are easily accessible and more cost effective. the primary objective of this study is to compare demographics and weight loss surgery outcomes between patients who participated in the online vs in-house preparative seminars. methods: after obtaining institutional review board approval, a retrospective chart review was performed involving patients who underwent bariatric surgery between january and december at a tertiary care center. the patients were divided into two groups based on their choice of educational seminar, online or in-house, prior to their initial consult with a surgeon. data was collected on age, type of insurance, length of stay (los), longest follow up and change in bmi to assess weight loss. results: one hundred and eighteen patients were included in this study. eighty patients attended in-house seminar while completed online seminar. the various types of surgery (laparoscopic gastric bypass, sleeve gastrectomy, and band) were similarly represented between the two groups. there was no difference in the type of insurance policy between the groups. patients who elected to take the in-house seminar were on average years older than those who chose the online course, which was statistically significant (p. ). there were no differences in los, longest follow up after surgery, and weight loss at months between the groups. conclusions: based on mbsaqip registry data, patients age or over did not have higher odds of a -day readmission compared to younger patients after lsg or lrygb. rates of -day readmission, reoperation, and death were similar, but rates of complications (e.g. pneumonias, unplanned intubations) were higher in the older group. bariatric surgery in the elderly should therefore be performed only after careful and patient-centered selection processes. introduction: revisional bariatric surgery has become more common in recent years. it is to address short and long-term complications of primary bariatric surgery as well as the issue of weight regain. the aim of this study was to retrospectively analyze the indications for reoperation and short-term outcomes in our institution. methods and procedures: between and , patients who underwent bariatric surgery in our center were included in a prospectively collected database. demographic data, primary and revisional bariatric procedures, reasons for revisions and outcomes were recorded and reviewed retrospectively. results: a total of patients underwent bariatric surgery at our institution and % of these (n= ) were revisional bariatric surgery. we identified groups of patients according to their primary procedures: adjustable gastric band (agb), roux-en-y gastric bypass (rygbp), vertical band gastroplasty (vbg), and sleeve gastrectomy (sg). of the patients, ( %) had abg as primary procedure. of those, % had their band removed due to food intolerance and severe dysphagia and % had a conversion to either rygbp or sleeve gastrectomy (sg) due to weight recidivism. in the rygpbp group (n= ), % of the patients presented with late complications. of these, % had an acute presentation (small bowel obstruction, internal hernia, or perforated marginal ulcer) requiring emergency surgery. only % patients needed gastric bypass takedown due to severe hypoglycemia. weight recidivism was noted in % of the patients that necessitated either revising the anastomosis, trimming of the gastric pouch or gastrogastric fistula takedown. in the vbg group (n= ), % of the patients experienced weight recidivism that required conversion to rygb and % of the patients required the vbg to be taken down due to obstructive symptoms. in the sg group (n= ), % of the patients experienced early complications needing a second procedure. weight recidivism was found as the most common reason for conversion ( %) to rygbp. twenty nine percent of the patients in this group underwent conversion to a rygbp due to severe de novo gerd. introduction: our aim was to systematically review the literature to compare weight loss outcomes and safety of secondary surgery after sleeve gastrectomy (sg), particularly between roux-en-y gastric bypass (rygb) and biliopancreatic diversion with duodenal switch (bpd-ds). sg was originally developed as the first part of a two-stage procedure for bpd-ds. however, it is now the most common standalone bariatric surgery performed in the united states. the majority of sg are done as the sole bariatric operation but in %, a second operation is necessary, due to insufficient weight loss, weight regain or reflux. the most common second-stage operations are rygb at % and bpd-ds at %. there are a few small case series comparing rygb to bpd-ds as a secondary surgery after sg. these studies suggest that after failed sg, bpd-ds results in greater weight loss but higher early complication rates than rygb. we had one mortality, related in part to supra-therapeutic anticoagulation perioperatively. one patient underwent successful heart transplantation and additional patients were reactivated on the transplant list. conclusion: laparoscopic sleeve gastrectomy is effective in advanced heart failure patients for meaningful weight loss, reactivation to the transplant wait list, and ultimately cardiac transplantation. however, this complex population carries a high perioperative risk and close multidisciplinary collaboration is required. more data is needed to best optimize perioperative management of these patients. the introduction: bariatric surgery is a highly effective treatment for severe obesity. while its effect on improvement of the metabolic syndrome is well described, its effect on intrinsic bone fragility and fracture propagation is unclear. therefore, the aims of this systematic review of the literature were to examine ( ) the incidence of fracture following bariatric surgery, ( ) the association of fracture with the specific bariatric surgical procedure ( ) conclusion: it appears that the overall risk of sustaining a fracture of any type after undergoing bariatric surgery is approximately percent after an average follow up of . years. the greatest risk of fractures is associated with the bpd, with the rygb being the most favorable. fractures following bariatric surgeries tend to follow osteoporotic and fragility patterns. post-operative supplementation of vitamin d, calcium and weight bearing exercises need to be optimized, and long term follow-up studies will be needed to confirm that these interventions will indeed reduce fracture risk following bariatric surgery. background: the effect of sleeve gastrectomy on gastroesophageal reflux (gerd) remains controversial. it is currently common practice to perform a hiatal hernia repair (hhr) at the time of the sleeve gastrectomy, however, there are few data on the outcomes of gerd symptoms in these patients. the aim of this study was to evaluate the effect of performing an esophagopexy hiatal hernia repair on gerd symptoms in morbidly obese patients undergoing robotic sleeve gastrectomy (rsg). methods: a single institution, single surgeon, prospectively maintained database was used to identify patients who underwent rsg and concomitant esophagopexy for hiatal hernia repair from november to july . patient characteristics, operative details and postoperative outcomes were analyzed. primary endpoint was subjective gerd symptoms and recurrence of hiatal hernia. results: thirty-seven patients were identified meeting the inclusion criteria (rsg+hhr+esophagopexy) with a mean follow-up of . over the past years there have been several bariatric surgeries cancelled secondarily to abnormal pre-operative test results within eastern health. these surgeries are often cancelled the day before their scheduled surgery, which does not provide sufficient time to book other patients. the end result is that the or gets underutilized and the bariatric surgery waitlist grows. prior to any major surgery patients are often subjected to a routine screening process, which includes a history and physical along with diagnostic screening tests and screening blood work. a preliminary analysis was done of the first patients through the bariatric surgery program at eastern health assessing the coagulation study results and outcomes. analysis showed that out of the first patients % were found to have a history of bleeding, % were using anticoagulants preoperatively, another % were noted to have a family history of bleeding. in the preoperative blood work that was done, % were found to have an elevated ptt/ inr for which hematology ended up being consulted in % of the patients. overall this did not change the preoperative management of these patients and they went on to have their surgery. intraoperatively patient was noted to have excessive bleeding and this was found not be associated with any preoperative elevation in their coagulation studies or family history of bleeding disorders. post operatively there was bleeding in patient which required transfusion, however this too was found not to be associated with any preoperative elevation in their coagulation studies or family history of bleeding disorders. overall this initial analysis showed no difference in operative management or delay in surgery secondarily to abnormal preoperative assessment findings. further analysis of a larger population of the bariatric surgery program patients is needed in order to determine whether any changes should be made to the preoperative assessment protocol. introduction: patients undergoing bariatric surgery frequently present with various obesity-related psychiatric comorbidities, including depression. furthermore, previous literature has demonstrated a positive association between depression and cardiovascular disease, and obesity serves as an independent risk factor for cardiovascular disease. however, the relationship between preoperative depression and cardio-metabolic risk factors following bariatric surgery remains unknown. methods and procedures: this retrospective analysis utilized data obtained from patients (n= , ) who underwent bariatric surgery at a single academic medical center in california. patients underwent either laparoscopic roux-en-y gastric bypass or sleeve gastrectomy. using medical record data, patients were preoperatively categorized as follows: not depressed, history of depression but not currently on anti-depressive medication, and history of depression and presently taking anti-depressive medication. patient demographic characteristics were obtained preoperatively. clinical and biochemical risk factors for cardiovascular disease were evaluated preoperatively and and months following bariatric surgery. anova, kruskal-wallis, and chisquare tests were applied where appropriate. results: in this sample, % of patients were not depressed, % had a history of depression but were not taking anti-depressive medication preoperatively, and % had a history of depression and were taking anti-depressive medication preoperatively. at baseline, depressive history was positively associated with female sex (p\. ), older age (p\. ), white race (p\. ), medicare insurance (p\. ), previous abdominal surgery (p\. ), length of stay (p\. ), requiring an inferior vena cava filter (p=. ), total cholesterol (p\. ), and triglycerides (p =. ). on average, patients with a history of depression taking anti-depressive medication weighed less than patients with a history of depression not on medication and patients without depression preoperatively (p=. ) and (p=. ) and (p=. ) months after surgery. after six months of follow-up, preoperative depressive history was positively associated with total cholesterol (p=. ), triglycerides (p\. ), hba c (p=. ), and fasting serum concentrations of insulin (p=. ). after months of follow-up, preoperative depressive history was positively associated with higher levels of total cholesterol (p=. ), ldl cholesterol (p=. ), and triglycerides (p= . ). conclusion: a history of depression prior to surgery was associated with higher levels of total cholesterol and triglycerides at baseline and and months postoperatively. after months, preoperative depressive history was also associated with higher levels of ldl cholesterol. this study suggests that, on average, bariatric patients with comorbid depression have worse lipid profiles prior to-and up to one year after-bariatric surgery relative to counterparts without depression. yen-yi juo, md, mph, yas sanaiha, md, erik dutson, md, yijun chen, md; ucla introduction: anastomotic leak is one of the most morbid complications of roux-en-y gastric bypass (rygb), yet its risk factors are ill-defined due to the rarity of the complication. we aim to identify both patient-and operative-level risk factors for anastomotic leak after rygb using a national clinical database. methods: a retrospective cohort study was performed using the metabolic and bariatric surgery accreditation and quality improvement program (mbsaqip) database. all adult patients who underwent laparoscopic or open rygb were included. multivariate logistic regression models were used to identify patient-and operative-level variables associated with development of anastomotic leakage. clinically relevant anastomotic leakage is defined as those that required readmission, intervention, or reoperation. introduction: hyperammonemia secondary to ornithine transcarbamylase (otc) deficiency is a rare and potentially lethal disorder. the prevalence of otc deficiency is reported to be : , to : , in the general population. otc deficiency has been reported in patients presenting with neurological symptoms after roux-en-y gastric bypass (rygb), and less than cases have been reported in the literature. the aims of this study are to examine the apparent incidence of this uncommon disorder in patients after bariatric surgery and to examine potential predictors of mortality. methods and procedures: this is a single center, retrospective study in a large, urban teaching hospital of postbariatric surgery patients who developed hyperammonemia from january to august . elevated plasma ammonia with an elevated urinary orotic acid level is accepted as consistent with a diagnosis of otc deficiency. all patients in our program are instructed on a post-operative diet containing grams/day of protein. descriptive and correlative statistics are calculated for all variables. results: between january and august , bariatric surgical procedures were performed at this single medical center. seven women with neurological symptoms had plasma ammonia levels above the upper limit of normal range. their average bmi is kg/m . two patients underwent vertical sleeve gastrectomy (vsg), underwent vsg with duodenal switch, and underwent rygb. all patients were hospitalized. the mean peak plasma ammonia level is umol/l (range: - ). the mean urinary orotic acid level is . mmol/mol creatinine (range: . - . ). there were patients with no orotic acid level checked, secondary to demise. no patient had clinical features or findings of progressive hepatic failure. there are four mortalities ( . %). serum folate and peak lactic acid levels are predictors of mortality with p-values of . and . respectively. the apparent incidence of otc deficiency is : in post-operative patients. conclusions: in our post-operative population, hyperammonemia results in a high mortality. its apparent incidence, secondary to otc deficiency, amongst bariatric surgery patients is higher than that reported in the general population. since otc deficiency is identified after multiple bariatric surgical procedures, further investigation will be important to examine potential mechanisms for its development which may include a genetic predisposition (possibly triggered by nutritional deficiencies), upper gut bacterial overgrowth (supported by elevated serum folate levels), or preexisting, subclinical hepatic dysfunction. introduction: the use of closed suction drains is associated with poor outcomes in many anastomotic operations and routine use is not recommended. in this context, intraoperative drain placement for primary bariatric surgery remains controversial. recent studies demonstrate that drains confer no benefit to patients; however, data are limited to descriptive single center experiences with low sample size. in order to characterize this practice gap, and implement evidence based recommendations, we sought to evaluate the use of closed suction drain and outcomes following primary bariatric cases using the mbsaqip registry. methods: we used data from the metabolic and bariatric surgery accreditation and quality improvement program (mbsaqip) public use file for patients who underwent a non-revisional laparoscopic roux-en-y gastric bypass (rygb), laparoscopic sleeve gastrectomy (lsg), or laparoscopic adjustable gastric banding (lagb). we excluded patients with asa status greater than or conversion to an open procedure. we analyzed demographics, preoperative comorbidities, procedure type for patients who did and did not undergo drain placement. adjusted rates of postoperative complications and mortality were then compared based on receipt of postoperative drain placement. results: of the , included patients who underwent laparoscopic bariatric surgery, , ( . %) underwent intraoperative drain placement. drains were more often placed in patients who underwent lrygb, were older, had higher preoperative bmi, had higher preoperative asa status, and had more comorbid conditions. after patient level risk adjustment, there was no difference in rates of leaks requiring intervention ( . % versus . %, p= . ) or mortality ( . % versus . %, p= . ) for patients with and without drains. in patients who underwent drain placement, there were higher rates of transfusion ( . % versus . %, p. ), reoperations for bleeding ( . % versus . %, p= . ), all reoperations ( . % versus . %, p. ), and surgical site infections (ssi) ( . % versus . %, p. ). conclusion: our analysis demonstrates that nearly one quarter of all laparoscopic bariatric surgery patients undergo drain placement. we found that drain placement is more common in preoperatively higher risk patients and following higher complexity procedures as suggested by associated increased rates of transfusion and reoperations for bleeding. we found no benefit to drain placement in terms of interventions for clinically significant leaks or mortality. finally, patients who underwent drain placement were more likely to develop ssi suggesting routine placement is not without risk. although further prospective studies are warranted, our analysis demonstrates that drains have the potential for harm with minimal protective benefit for patients after primary bariatric surgery. sleeve gastrectomy ( % n= ) and laparoscopic roux-en-y gastric bypass ( % n= ) were the two types of surgeries done in our population. the risk of developing atrial fibrillation was calculated preoperatively and found a -fold higher risk in females and -fold greater risk in males when compared with the ideal risk for each category. at months follow-up the preoperative risk was . ± . % with an absolute risk reduction of . % corresponding to a relative risk reduction of . % with males having a more significant change at months follow-up. these findings and the electrocardiographic changes at months follow-up are better described in background: the sleeve gastrectomy (lsg) is the most popular procedure worldwide to treat obesity. among those that are obese, gerd has a prevalence of . percent. many surgeons do not perform lsg in these patients because only . percent of symptomatic patients showed resolution of gerd-like symptoms after concomitant sleeve gastrectomy with hiatal hernia repair. many surgeons perform the gastric bypass on gerd patients with hiatal hernias because they believe its superior for the resolution of gerd. when they do this they overlook the many long term complication associated with gastric bypass. also, many patients do not want the gastric bypass under any circumstances. surgeons need to be open to finding better way to reduce the high recurrent rates of gerd after lsg. materials and methods: this is a single institution, multi-surgeon, retrospective study involving morbidly obese patients in a prospectively kept data base from january of through july of . these patients all had gerd with preoperatively identified hiatal hernias on egd. all patients were dependent on anti-reflux medications. there were ( . %) males and ( . %) females. bmi ranged from to . hiatal hernias measured from cm to cm. all lsg patients received a primary crural closure, with or without gore bio a mesh placement, at least weeks prior to the sleeve gastrectomy. post-operatively, patients were interviewed for gerd symptomatology and anti-reflux medication dependency. results: of the patients, ( . %) patients had resolution of gerd-like symptoms and off all anti-reflux medications after the staged hiatal hernia repair and sleeve gastrectomy. patients ( . %) had improvement of gerd but still dependent on anti-reflux medication. patients ( . %) had no resolution or improvement of gerd. there was one post-operative complication of laryngospasm with pulmonary edema status post extubation. there were no mortalities in the series. conclusions: in this study, staged hiatal hernia repair, at least weeks prior to sleeve gastrectomy, doubled the published rate of gerd resolution from % to %. % showed improvement in symptoms at one year. this rate is comparable to gerd resolution after gastric bypass. this may be an alternative approach to hiatal hernias in the morbidly obese patient with gastroesophageal reflux disease who do not want a gastric bypass. background: bariatric surgery is a common procedure in general surgery. gastric bypass has been performed laparoscopically for over two decades and multiple techniques are described. the circular stapled anastomosis, one of the earliest methods for gastrojejunostomy, is performed in two ways: a transoral method to introduce the anvil and a transabdominal approach developed later. the former technique requires passing the anvil of the circular stapler through the mouth, down the esophagus, and into the gastric pouch. in the latter method, a gastrotomy is made, the anvil is introduced, and the gastrotomy is stapled off, creating the gastric pouch. this study aims to objectively compare the two methods of circular stapled gastrojejunostomy in terms of surgical site infection (ssi) rate. methods: a retrospective chart review of patients undergoing laparoscopic roux-en-y gastric bypass with one of two surgeons at a bariatric center of excellence in an academic hospital from january introduction: laparoscopic sleeve gastrectomy (lsg) has become the most commonly performed procedure in the treatment of morbid obesity, but there is significant variability in its performance. from national database analysis, more restrictive sleeve construction, based on smaller bougie size, has not correlated with greater weight loss. we hypothesize that bougie size is not reflective of actual restriction, or that sleeve restriction does not correlate with weight loss. we performed qualitative and volumetric analysis of immediate post-sleeve contrast studies to determine the association of sleeve restriction with post-operative weight loss and complications. methods: between and , patients underwent immediate post-sleeve contrast studies. based on standardized vertebral body height assessment by preoperative chest radiograph, sleeve diameter at intervals (including the narrowest point) was measured in mm, and the volume above the narrowest point of the sleeve was calculated. sleeve shape was assumed as dual-tiered or simple truncated cone based on morphology. sleeve restriction, morphology and volumetric analysis were associated with clinical outcomes including complications, post-op symptoms, and weight loss at months. background: variability in surgical technique resulting in narrowing at the incisura angularis, twisting along the staple line, and retention of the gastric fundus has been implicated in increased gastroesophageal reflux disease (gerd) following laparoscopic sleeve gastrectomy (lsg). standardizing creation of the sleeve based on anatomic landmarks may help produce more consistent sleeve anatomy and improve outcomes. methods: a retrospective review of all patients undergoing lsg from january to november at a single institution specializing in bariatric surgery was performed (n= ). patients underwent either traditional lsg with use of a f suction bougie to guide creation of the sleeve (n = ) or anatomy-based sleeve gastrectomy (abs, n= ). abs was performed using a gastric clamp to maintain predetermined distances from key landmarks ( cm from gastroesophageal junction, cm from incisura angularis, cm from pylorus) during stapling. patient demographics, perioperative characteristics, and post-operative outcomes were compared using chi-square and student's t-tests as required. helicobacter pylori (hp) is prevalent in up to % of the population worldwide with increased rates observed in the bariatric population. bariatric surgery has seen a rapid expansion over the last years with the growing rates of severe obesity. higher hp rates are thought to be associated with increased rates of postoperative complications including increased marginal ulceration and leak rates. accordingly, some bariatric centers have adopted routine pre-operative screening and hp eradication programs. yet, while hp correlation with gastritis and malignancy has now been well defined, its impact on patients undergoing bariatric surgery remains unclear. background: the risk of developing a hiatal hernia in the obese population is . fold compared to patients with a bmi \ . most hiatal hernias after bariatric surgery are asymptomatic and when symptoms are present they may be difficult to differentiate from overeating or maladaptive eating habits. the aim of this study was to define the risk and symptoms associated with a hiatal hernia in the post-bariatric surgery cohort. methods: a retrospective review of prospectively collected data for patients who underwent laparoscopic hiatal hernia repair who previously had primary roux-en-y gastric bypass (rygb) or sleeve gastrectomy (sg). data collection spanned a five-year interval ( / - / ). preoperative and follow up data were collected from medical records and questionnaires in the clinic or by telephone. variables obtained include age, gender, psychiatric history, pre-index procedure bmi, pre-hiatal hernia repair bmi, post-hernia repair bmi, pre and post operative symptoms, and associated morbidity. all hiatal hernia repairs were done laparoscopically, with posterior cruroplasty after circumferential hiatal dissection. results: we identified patients with a symptomatic hiatal hernia who had previously (range: - years) underwent bariatric surgery. fourteen rygb patients presented at a mean of . years compared to sg patients who presented at a mean of . years after index procedure. diagnosis was by a combination of ugi ( %), ct scan ( %) and egd ( %). mean follow up was . months (range: - months). laparoscopic hiatal hernia repair was successfully performed in all patients with % mortality. dysphagia and regurgitative symptoms markedly improved in [ % of patients however, nausea, vomiting and abdominal pain were not changed in - % of patients ( figure) . conclusion: hiatal hernia following bariatric surgery is a rare but important cause of bloating manifested as nausea and vomiting, abdominal pain, regurgitation or reflux, and food intolerance or dysphagia (barf)-and should be further evaluated with imaging or endoscopy when present. laparoscopic repair of hiatal hernia is warranted and results in resolution of symptoms in the majority of symptomatic patients. mid-term outcomes of sleeve introduction: obese patients suffer from multiple organ comorbidities which contribute to a shortened lifespan. one of the effects of obesity is thought to be pseudotumor cerebri, which is secondary to increase in intracranial pressure (icp) in the absence of an obstruction. over the past two years, we have measured icp after insufflating with a laparoscopy device. we found that icp increases dramatically and it correlates with the amount of insufflation in the abdomen. over the years, there have been studies in obese patients and intra-abdominal pressure. these studies have shown that some obese patients have an intra-abdominal pressure of - mmhg. increasing intraabdominal pressure is thought to escalate intracranial pressure (icp). the objective of this pilot study was to observed change in icp after the raising intra-abdominal pressure. method: in this retrospective chart review preliminary study, pressure in each of the patients either normal pressure hydrocephalous or high pressure hydrocephalous receiving a ventricle shunt were measured by manometer. once the shunt was placed into the ventricle, we attached a manometer to measure the opening pressure. after we accessed the abdominal cavity using the standardoptiview technique, we created a pneumoperitoneum. after achieving an intraabominal pressure of mmhg, were measured the icp using the manometer. spss software version was used for data analysis. paired t-test was applied on icp before and after the procedure. introduction: postoperative bleeding represents an infrequent, yet serious complication after bariatric surgery. differences in the rate of postoperative bleeding reported for the two most common weight loss procedures-laparoscopic roux-en-y gastric bypass (lrygb) and laparoscopic sleeve gastrectomy (lsg)-are ostensibly confounded by patient and surgeon specific preoperative, intraoperative and postoperative factors, in particular, by the utilization of staple line reinforcement or oversewing. with this understanding, we aim to use a large national database to definitively characterize differences in bleeding rates between lsg and lrygb. conclusions: after appropriate risk-matching, lsg patients have a reduced likelihood of a postoperative bleeding event compared to those undergoing lrygb. this difference is likely more pronounced with intraoperative securing of the staple line via oversew, buttress or an alternative method. these findings from a large national database represent an important consideration for surgeons and patients alike when evaluating the appropriate bariatric operation. background: bariatric surgery has shown to be the most effective treatment, with documented improvement in obesity-related comorbidities. the type of health insurance coverage plays an important role in the access to bariatric surgery, but might also affect postoperative outcomes. the objective of this study is to determine whether there is a difference in outcomes based on the type of insurance months after bariatric surgery. methods: we retrospectively reviewed all the patients that underwent bariatric surgery at our institution from to . we divided the patients into two groups, based on the type of insurance, private (group one), and public (group two). we compared demographics and months outcomes between the groups, using t-test for continuous variables and chi-square for categorical variables. we also compared months estimated bmi loss between different private insurances using anova. introduction: bariatric surgeons are now performing primary and revisional procedures on the extremes of age. there is controversy surrounding the safety and effectiveness of bariatric surgery among older age groups compared to younger age groups. to address this knowledge gap, we designed a study assessing short-term bariatric surgery outcomes among various age groupings across a large national database. methods and procedures: de-identified patient data across from the mbsaqip registry was used. age groupings were organized into young, middle-aged, and older adults (in years) as follows: \ , - , and [ , respectively. the following -day outcomes were evaluated between all possible pairwise age groupings: mortality, surgical site infection (ssi), and readmission; logistic regression was used to compare outcomes between age groupings controlling for primary vs. revisional index operation, patient factors, and procedure factors. a p value of . was deemed statistically significant. results: a total of , patients were identified (age range: to [ ); % (n= , ) underwent primary bariatric operations while % (n= , ) underwent revisional cases. older adults had significantly worse outcomes than middle-aged and younger adults, respectively, for over comparisons across all outcomes; in contrast, younger adults had significantly worse outcomes than middle-aged adults for only comparisons across ssi and readmission. for primary bariatric cases, older adults had significantly higher mortality rates than middle-aged and younger adults, respectively, in the following categories: asa , laparoscopic sleeve gastrectomy (lsg), or laparoscopic roux-en-y gastric bypass (lrygb). for revisional cases, older adults had significantly higher mortality rates than middle-aged and younger adults, respectively, in the setting of female gender, caucasian race, or asa . regarding ssi, older adults undergoing primary lrygb had significantly higher organ space infections compared to younger adults. in addition, older adults who had revisional lrygb had significantly higher deep surgical site infections compared to middle-aged adults. following primary bariatric cases, older adults had significantly higher readmission rates compared to younger adults in the presence of male gender, caucasian race, asa , copd, or after lsg. following revisional cases, older adults had significantly higher readmission rates than middle-aged and younger adults, respectively, in the setting of pre-operative chronic steroid use. conclusions: overall, older adults had worse short-term outcomes compared to their younger counterparts following primary and revisional cases. further research is required to investigate these findings with the goal of targeting interventions to improve outcomes among bariatric surgical patients. background: the obesity epidemic in the united states has been accompanied by surge in bariatric surgery. nearly , bariatric procedures were performed in the us in , % of which involved roux-en-y gastric bypass (rnygb). while rnygb has proven an effective tool in combating obesity, it also alters a patient's anatomy in a way that makes traditional ercp a difficult, if not impossible option for interrogating the common bile duct. one way to approach the post-rnygb patient with obstructive jaundice is to access the peritoneal cavity via a laparoscopic/ robotic approach followed by direct cannulation of the gastric remnant with a laparoscopic port, allowing passage of an endoscope. the aim of this study was to evaluate our single center experience with minimally-invasive transgastric ercp (tg-ercp) from to . methods: we compiled a list of all patients who underwent laparoscopically or robotically assisted tg-ercp at our institution from - . we then examined patient demographics, procedural details, postoperative outcomes, and success rate, with success defined as cannulation of the ampulla, clearance of obstruction if present (stones/sludge/stenotic ampulla), and completion imaging of the biliary and pancreatic ducts. results: patients were included in the study. cases were performed robotically ( %), and laparoscopically ( %). ercp was successful in cases ( %). all unsuccessful attempts were aborted when the endoscopist was unable to pass the scope through a tight pylorus. median time of operation was minutes ( minutes if concomitant cholecystectomy was performed, minutes if not). median length of stay after operation was days (range - days). median estimated blood loss (ebl) was ml. post ercp pancreatitis occurred in patients ( . %), and was mild and self limited in all cases. patients had postoperative bleeding requiring transfusion. both of these had concomitant cholecystectomy. discussion: in patients with biliary obstruction and anatomy not suitable for traditional ercp, tg-ercp is a viable option. it can be performed with in a minimally invasive fashion (either laparoscopically or robotically) with a high success rate and low morbidity. as the population of patients who have undergone rnygb continues to grow, so does the likelihood of encountering one with obstructive jaundice. tg-ercp, therefore, should be thought of as an essential tool in the armamentarium of the general surgeon. introduction: primary palmar hyperhidrosis (ph) is a pathological condition of over perspiration caused by body produces an excessive amount of sweat. this disorder affects to decrease quality of life of patients. thoracoscopic sympathectomy is minimally invasive and an effective procedure to treat hyperhidrosis. different of level of sympathectomy has been debate for the best outcomes. many researchers studied about short term outcomes but no empirical research evidences long term outcomes of thoracoscopic sympathectomy in thailand. this study purposed to evaluate and compare the long term clinical outcomes between patients who underwent t and t thoracoscopic sympathectomy for ph with particular attention to patient satisfaction and quality of life. methods and procedures: sixty patients with ph underwent thoracoscopic sympathectomy. patients were divided into two groups by the level of thoracoscopic sympathectomy as t group and t group. they were investigated the improvement of sweating, compensatory sweating, satisfaction and quality of life. the long-term investigation was designed to examine clinical outcomes at before surgery, six months after surgery, year after surgery, years after surgery, and last follow up days were compared within group and between of t and t group. they were subjected to telephone interview using multiple questionnaires to investigate surgery outcomes, degree of satisfaction, and quality of life improvement. results: sixty patients responded to the telephone interview. patients demographic data and also recurrence rate of ph between t and t group was not significant different (p= . ). both groups improved severity of sweating without any statistical significant. but the t thoracoscopic sympathectomy led to significantly lower incidence of compensatory hyperhidrosis when compared with t group at back and trunk sites. the t group had higher overall satisfaction than t group with was not significantly different. long term result are followed after years. conclusions: there was no difference in decreasing severity of sweating between t and t level of thoracoscopic sympathectomy. both group equally archived patient satisfaction. but the t level of thoracoscopic significantly had lower severity of ch and better quality of life in long term period. introduction: acute pancreatitis due trauma is commonest cause of pseudocyst in pediatric age. due to limited literature available and under diagnosis by pediatricians, the true incidence of pseudocyst in - age group is not known. material and methods: retrospective analysis of pediatric age ( - years) patients who underwent laparoscopic cystogastrostomy at distric teaching hospital was done. patients data, presentation, investigations, opetation done and post operative course was studied. result: total of patients ( males & females) had mean age of . years, mean weight of kg. etiollogies included blunt abdominal trauma ( ), idiopathic ( ), gallstones ( ) . average cyst diameter was . cm. laparoscopic cystogastrostomy by transgastric approach was successfully possible in cases with no conversion. cystogastrostomy was performed using sutures in patients and ultrasonic energy device in patients. gastrotomy was closed with sutures in all cases. mean operative time was minutes. post operative imaging at months revealed no persistence or recurrence of cyst. conclusion: minimally invasive laparoscopic approach for chronic pancreatic pseudocyst in pediatric age group is safe and effective strategy and should be adopted as primary modality of treatment. introduction: videoscopic neck surgery is developing despite the fact that only potential spaces exist in the neck. gagner first described the endoscopic subtotal parathyroidectomy with constant co gas insufflations for hyperparathyroidism in . the cervical approach utilizes small incisions in the neck thus making it cosmetically unacceptable and cannot be used for lesions greater than cm. the axillary approach makes it difficult to visualize the opposite lobe. the anterior chest wall approach utilizes port access at various positions on the anterior chest wall depending on the surgeon. this technique also allows bilateral neck exploration. hence we have been able to perform total thyroidectomies with central compartment clearance for papillary carcinoma and near-total thyroidectomies for large multinodular goiters, materials and methods: three incisions subplatysmal plane pneumoinsufflation with carbon dioxide (co ) ports creating a subplatysmal palne dissection begins at the inferior pole posterior dissection clipping superior thyroid vessels specimen freed up thyroid lobectomy was performed in the twenty cases. the average blood loss was ml mean operative time was min there were no complications and no cases were converted to open. there were no cases of recurrent laryngeal nerve injury or postoperative tetany. no subcutaneous emphysema, ecchymosis or hypercarbia was observed in any patient. all patients were discharged on the second postoperative day except the first on the fifth day. in conclusion this approach seems to be safe in case of unilateral lobectomy but early to say it is superior to conventional thyroidectomy especially in total thyroidectomy. introduction: laparoscopic sleeve gastrectomy (lsg) is one of the most commonly performed weight loss surgeries. prolonged hospital admissions are associated with both increased morbidity and mortality and increased strain on the health care system; studies are now investigating the safety and feasibility of outpatient lsg. this study examined a single surgeon's postoperative admission trends for patients who underwent lsg. the patients were divided into two cohorts based on the date of surgery, and we hypothesize institutional experience has a significant impact on postoperative stay and hospital readmission rate. methods: this is a retrospective study on lsgs performed by a single surgeon in a tertiary center from - . inclusion criteria: patients [ years old, bmi [ with comorbidities or bmi [ , and patient approval by the bariatric surgical program in victoria, british columbia. patients with prior weight-loss surgery were excluded. patients were discharged home on a care plan involving: nurse and surgeon telephone follow-ups within one week post-surgery. patients were divided into two cohorts: cohort a (procedures between - inclusive) and cohort b (procedures between - inclusive). results: patients were included in this study: females ( . %) and males ( . %). the mean preoperative age was . ± . years, and the mean preoperative bmi was . ± . kg/m . the average postoperative discharge day for the population was day . ± . and the average or time was . ± . minutes. one patient in cohort b was re-admitted pod with a diagnosis of postoperative edema managed conservatively and is included in the analysis as pod . a second patient in cohort b returned to hospital (pod ) for abdominal pain and was managed conservatively as outpatient. conclusion: there was a significant difference in the average postoperative discharge day between patients in cohort a and cohort b who underwent lsg with patients in cohort b requiring a shorter average admission time. this study suggests that with increasing institutional experience and a postoperative discharge plan, patients undergoing lsg may be discharged on postoperative day one safely. surg endosc ( ) introduction: minimally invasive techniques have revolutionized the art of the surgical practice. the laparoscopic approach to cholecystectomy has become the gold standard and is the most common laparoscopic general surgery procedure worldwide. in an effort to further enhance the advantages of laparoscopic surgery, even less invasive methods have been attempted, including smaller and fewer incisions. the objective of this study was describing our results of years of needlescopic cholecystectomy. methods: since march all patients that underwent to needlescopic cholecystectomy micro-laparoscopic procedure with instruments of mm were included in this study in a prospective database and the information was analyzed. results: between march and september , needlescopic cholecystectomies have been done at texas endosurgery institute in san antonio, texas by a single surgeon. % of the patients were female. the average age was . (range of - years old). average operating time was . minutes (range of - minutes). the minute operation required laparoscopic cbd exploration, accounting for the extended time. average estimated blood loss (ebl) was cc (range of - cc). % of cases required conversion to standard mm cholecystectomy and was completed without incidents. all patients were followed up at weeks, weeks, and months after the procedure. only patient presented with a hernia at the umbilical site. otherwise no wound, bile duct, bile leak, bleeding or thermal injury complications were identified. conclusions: micro-laparoscopic procedures with mm instruments in this specific procedure of needlescopic cholecystectomy is safe and feasible, and is a cosmetic alternative to the standard laparoscopic cholecystectomy. there's still less report about thyroid cancer cases in toetva. this study reviews all cases of thyroid cancer which surgery were performed. there were cases of toetva in thyroid cancer and cases of opened thyroidectomy. objective: to review and report in terms of surgical outcome, complication, post-surgical treatment and recurrence in all cases of thyroid cancer surgery, especially in toetva technique. material and methods: from march -july in police general hospital, a total of patients underwent toetva with cases of toetva in thyroid cancer and cases of opened thyroid surgery in thyroid cancer. all patients were recorded in multiple parameters. results: this study have total of thyroid cancer cases which cases ( %) were male and cases ( %) were female, with an average age of . most clinical presentation was thyroid mass or nodule which was at cases ( . %), case ( . %) was non-toxic goiter and case ( . %) was grave disease. the clinical presentation mean time was . years ( weeks- years). there were cases ( . %) with a mass at right lobe, cases ( . %) with a mass at left lobe, and cases ( . %) with mass at both lobes. the size of thyroid mass was . ± . centimeters ( - centimeters). there were cases ( . %) had euthyroid, case ( . %) had subclinical hyperthyroid, cases ( . %) had subclinical hypothyroid, and cases ( . %) had hyperthyroid. for type of surgery, there were cases ( . %) of toetva surgery and cases ( . %) of opened total thyroidectomy. most patients at cases ( . %) didn't have any post-operative complication. and there were hypothyroid cases ( . %), transient hypocalcemia with no symptom cases ( . %), and transient hoarseness cases ( . %). after toetva surgery performed, cases ( . %) were redo completion thyroidectomy, cases ( . %) were transaxillary completion thyroidectomy, cases ( . %) were redo toetva, and case ( . %) deny for reoperation. and cases ( %) didn't have any complication after redo surgery, cases ( . %) were hypothyroid, cases ( . %) were hypocalcemia and hypoparathyroid, and case ( . %) was transient hoarseness. after did thyroidectomy, ultrasound neck shown that cases had no residual or recurrence thyroid mass, cases had residual thyroid tissue. all cases received radioactive iodine ablation. radionuclide total body scan showed no evidence of distant functioning metastasis. conclusion: three-year short-term followed up toetva in thyroid cancer has shown less complication and no recurrence cancer. objective of the study: sentinel node navigation surgery (snns) in gastric cancer has been investigated for almost two decades in an effort to reduce operative morbidity. indocyanine green (icg) with enhanced infrared visualization is one technique with increasing evidence for clinical use. we are the first to systematically review and perform metaanalysis to assess the diagnostic utility of icg and infrared electronic endoscopy (iree) or near infrared fluorescent imaging (nifi) for snns exclusively in gastric cancer. methods and procedures: a search of electronic databases medline, embase, scopus, web of science and the cochrane library using search terms "gastric/stomach" and "tumor/carcinoma/cancer/neoplasm/adenocarcinoma/malignancy" and "indocyanine green" was completed in may . all human, english language randomized control trials, non-randomized studies, and case series were evaluated. articles were selected by two independent reviewers based on the following major inclusion criteria: ( ) diagnostic accuracy study design; ( ) indocyanine green was injected at tumor site; ( ) iree or nifi was used for intraoperative visualization. the primary outcomes of interest were identification rate, sensitivity and specificity. titles or abstracts were screened after removing duplicates. the quality of all included studies was assessed using the quality assessment of diagnostic accuracy studies- . results: ten full text studies were selected for meta-analysis. a total of patients were identified with the majority of patients possessing t tumors ( . %). pooled identification rate, diagnostic odds ratio, sensitivity and specificity was . ( . - . ), . ( . - ), . ( . - . ) and . ( . - . ) respectively. the summary receiver operator characteristic for icg+iree/nifi demonstrated a test accuracy of . %. subgroup analysis found improved test performance for studies with low risk quadas- scores, studies published after and submucosal icg injection. iree had improved diagnostic odds ratio, sensitivity and identification rate compared to nifi. heterogeneity among studies ranged from low (i \ %) to high (i [ %). conclusions: the idea of snns in gastric cancer is intriguing because of the potential to limit operative morbidity. we found encouraging results regarding the accuracy, diagnostic odds ratio and specificity of the test. the sensitivity was not optimal but may be improved by a carefully planned and strict protocol to augment the technique. given the limited number and heterogeneity of studies, our results must be viewed with caution. objective: to evaluate the feasibility, cost effectiveness and safety of single incision laparoscopic surgery using routine laparoscopy instruments. method: cases of acute appendicitis and cases of symptomatic gallstone disease were included in study. cases were enrolled in study and prospective observational study was performed. ruptured appendicitis/abscess formation were excluded from study. similarly empyema gallbladder/gallbladder perforation were also excluded. results: total cases included; cases of appendicitis and cases of symptomatic cholelithiasis. mean age of appendectomy group was . ± . years and mean age of cholecystectomy group was . ± . years. in our study, mean operative time for sil appendectomy was . ± . min. post-operative fever was noted in cases ( . %). mean post-operative pain as per vas score taken after hours, on pod was . . average post op stay in hospital was . days, port site infection occurred in one case ( . %). patient satisfaction score obtained on the scale of - on one month follow up was . , while scar cosmesis score was . . in our study, cases underwent sil cholecystectomy, of which were male ( . %) and were females ( . %), and mean age of patients was . yrs. mean operative time in our study was . min, mean post-operative pain taken on pod as per vas score was . , mean post-operative hospital stay was . days, port site infections occurred in cases. post-op fever was noted in cases, post-operative patient satisfaction score obtained at month follow up was . and scar score of . on the scale of - . no case required drain placement and conversion. conclusion: sils can be performed using conventional laparoscopic instruments especially in a government setup where per capita economic burden to patient will be less. though it has more operative time, it has comparably less post-operative hospital stay, causes less pain, and has significantly more patient satisfaction regarding post-operative scar and cosmesis. since sils has more patient acceptance and satisfaction, it can be offered to all patients undergoing laparoscopic surgery. it is very useful in government setup where lower economic class of patients will also benefit, irrespective of unavailability of special instruments and financial constraints, as it can be performed using routine laparoscopic instruments. in the year we started to practice the pericardic window by laparoscopy to diagnostic of head injury hidden in precausal trauma, although lucketally for our society, this type of injury has decreased considerably, we have achieved an important number of patients and in the last year we have performed the procedure for another type of pathologies and also diversified the approach route according to the case. objective: sharing accumulated experience in years in the pericardic window practice by laparoscopy or thoracoscopy. material and methods description of cases results: during this period, we have accomplished cases of laparoscopic pericardal window with two unique ports for the diagnosis of head injury in trauma precordial, additionally there were practiced windows through traumatic trauma of which have been derived in treatment of cardiac injury on this way, without performing open approach. in another scenario, we have performed pericardial spill treatments for different causes by minimally invasive via. no complication or mortality associated with the procedure has been presented. conclusions: the pericardic window performed by a minimally invasive surgery is an effective, replicable strategy for the management of diagnosis and the medical and traumatic treatment of this pathology. patient selection is key and work in multidisciplinary groups guarantees good results. introduction: for the transabdominal preperitoneal repair (tapp) for groin hernia, single port surgery (sps) has been reported to reduce the abdominal wall damages. to reduce the length of the umbilical scar and to keep the view of triangulation, we use one needle forceps plus sps. patients and methods: from may to july , consecutive tapp patients were retrospectively investigated. there were male and female. we use two mm ports ( for the scope and for the operator's right hand forceps) through an umbilical multi-channel port and additional mm needle instrument is pierced above the pubic bone. a mm flexible scope allowed us to keep the triangular formation easily. we studied the safety and usefulness of this method from the viewpoints of operation time and the complications. results: median operation time of single side hernia ( cases) was min ( - ) and the bilateral case ( cases) was min ( - ). five cases needed one or two additional mm ports, and one case with severe preperitoneal adhesion due to the previous prostate cancer surgery was converted to open method because of the venous bleeding. other complications were spermatic cord injury and postoperative seroma that required the percutaneous puncture. umbilical scars and the pierced needle instrument scars became gradually invisible within or months. there were no incisional hernia nor wound infections in our series. these data was comparable to the conventional laparoscopic hernia repairs. conclusions: operation scars of this method had better cosmesis than the conventional tapp or sps tapp, and there were no differences between our sps-tapp with one needle foerceps and conventional method in operation time and the complication rate. our method was demonstrated as a less invasive approach for laparoscopic groin hernia repair. clinical application: fj clip is a stainless steel that can be used to hold organs in the abdominal cavity. it is available in two sizes: mm and mm. the device is short, it has a strong grasp, and it causes no or only negligible organ damage. we have used fj clip in the performance of local gastric excision (n= ), colectomy (n= ), and cholecystectomy (n= ) with no resulting difficulty. f loop plus is a g stainless steel loop-like device into which we can insert φ . mm nt alloy thread, which we draw out extracorporeally via simple puncture. laparoscopic total and proximal gastrectomy. we made a small incision at the umbilicus and inserted a -mm camera port and -mm metal cannula. we placed two (left and right) epigastric ports. retraction of the left hepatic lobe was easy with use of the -mm fj clip and a -mm penrose drain. for # lymph node dissection, we used the fj clip to grasp the upper part of the stomach, inserted the f loop plus from the upper right abdomen. for # dissection, we grasped the pyloric vestibule and pulled it leftward. for dissection of the upper edge of the pancreas, we grasped the left gastric arteriovenous pedicle and pulled it toward the abdomen. the fj clip's grasp and traction exerted on the stomach wall were strong and effective, and there was little organ damage. reconstruction (roux-y) or double tract were performed within the abdominal cavity by hand-sewn purse string suture of the esophageal stump, insertion of an anvil, and use of an automated anastomosis device. we have experienced total and proximally cases to date, but there have been no complications, and both intraoperative bleeding and operation time were within normal limits. conclusion: we believe the fj clip and f loop plus will replace conventional forceps for various tasks in reduced port gastrectomy. introduction: pulmonary anatomical resection is considered as standard treatment for early staged lung cancer. uniportal video-assisted thoracoscopic surgery (uvats) has recently showed favorable surgical outcomes, but remains technically demanding, especially in a complex procedure such as anatomic segmentectomy. needlescopic instruments facilitates complex laparoscopic surgeries with nearly painless and scarless postoperative outcomes, however, its utilization of thoracoscopic surgery were mostly for minor procedures such as bullectomy and sympathectomy. we presented our initial experience of lung cancer surgery performed by uniportal vats and additional needlescopic instruments, and we also compare the operative results with conventional uniportal vats. methods: from december to august , consecutive patients with lung cancer undergoing anatomical lung resections including lobectomies and segmentectomies were reviewed retrospectively. of these patients, patients received conventional uniportal vats (uvats), and patients received needlescopic-assisted uniportal vats (na-uvats). we compared the peri-and post-operative outcomes in these groups. results: there was no significant difference in demographic, anesthetic, or operative characteristics in two groups except for age. the mean operation time was statistically less in the na-uvats group ( . ± . min vs . ± . min, p= . ). the intraoperative blood loss was significantly less in the na-uvats group ( . ± . ml vs . ± . ml, p= . ). there were two major pulmonary arterial bleeding events and one conversion to thoracotomy in the uvats group. the hospital stay, duration of chest tube drainage and post-operative pain scale were comparative in the two groups. conclusion: under the assistance of additional needlescopic instruments, uniportal vats can be performed more efficiently and safely without compromising its benefit in less postoperative pain and early recovery. purpose: we applicated the v-loc into abdominal wall closure in single incision laparoscopic appendectomy (sila) from . the aim of our study is to present our experience of abdominal wall wound closure technique using barbed suture in sila and comparision of perioperative outcomes with conventional method of layer by layer abdominal wall closure after sila. methods: from august to june , sila was performed on patients with acute appendicitis at the department of surgery, hallym sacred heart hospital. under approval of institutional review board, data concerning demographic characteristics, operative outcomes, postoperative complications were compared between both v-loc closure group and conventional layer by layer closure procedures. in v-loc closure group, after removing the appendix, divided linear alba was closed using unidirectional absorbable barbed suture v-loc - with continous running fashon. begins at the end of incision, and coming back with reinforced running. subcutaneous closure was also done using same thread, and the subcuticular suture along incision line was performed with remaning portion of v-loc. results: the demographic data of patients's characteristics were similar between the two groups. the use of barbed suture significantly reduced the suturing time for abdominal wall closure (p= . ) compared with conventional suture. the postoperative incision length was significantly shorter in v-loc group than conventional group (p= . ). the rate of surgical site infection were similar in both group. no incisional hernia were noted in both group with median follow up periods of . months. the total costs of the procedure were comparable in both group under korean drg system. the use of barbed suture in abdominal wall closure in single port laparoscopic appendectomy is safe, and feasible method, reduces the suturing time, thereby decreasing the total operation time, and incision length with cosmetic effect. angela m kao, md, michael r arnold, md, julia e marx, paul d colavita, md, b todd heniford; carolinas medical center introduction: morgagni hernia is an anteromedial congenital diaphragmatic hernia seen in approximately in live births and rarely identified in adulthood. patients may be asymptomatic, have intermittent symptoms, or present acutely with incarceration/obstruction. given this, surgical repair is recommended, but a standardized technique has not yet been described. methods: a prospectively collected hernia-specific database was queried for all adult morgagni hernias performed at a tertiary hernia center. demographics and peri-operative data were compared. ( ) repair. the most common ( . %) method of repair included suturing mesh to the diaphragmatic portion of the defect and securing the anterior-inferior edge to anterior abdominal wall with transfascial sutures and/or tacks. four patients ( . %) underwent primary repair. average defect and mesh size was . cm and . cm , respectively. three patients ( %) underwent a concomitant paraesophageal hernia repair. mean ebl and length of stay was ml (range - ml) and . days (range - days). postoperative morbidity included transient postoperative hypoxemia ( patients) and pleural effusion ( ) . there was no mortality, mesh complications or recurrences with a mean follow-up of months. conclusions: morgagni hernias patients were more often older, obese, and women. these hernias remained unrepaired in % of patients despite their having had previous abdominal surgery. a laparoscopic or robotic approach offers an effective hernia repair with minimal complications, short hospital stay, and excellent long-term results for both elective and acute operations. mesh repair, sutured to the diaphragm and sutured/tacked to the abdominal wall, appears to be a very successful means to repair larger defects. introduction: hydatidosis is a zoonotic disease caused by echinococcus granulosus. it is endemic in the mediterranean, south america and middle east. it is a systemic disease wherein lungs are the second most common organ involved, after liver. radio-imaging plays an important role in diagnosing and determining the extent of the disease. surgical enucleation of cyst has been the classical treatment for this disease. bilateral lung involvement has been traditionally treated by median sternotomy or a bilateral thoracotomy. video assisted thoracoscopic surgery (vats) is an effective surgical approach in such settings. materials and methods: at our center, we have operated cases of pulmonary hydatidosis thoracoscopically over the past years. in all cases, area around the cyst was cordoned off with . % cetrimide soaked gauze pieces. a pericystotomy is performed with ultrasonic shears & the germinal membrane is delivered en masse into an endo-bag. an air leak test after saline instillation into the cavity, is a standard part of the procedure. for those cases with cysto-bronchiolar communications, the defect was sealed by either suturing or glue application. traditionally, bilateral cases & cysts larger than cm in size were tackled by an open approach. but, in our experience, cyst size, bilaterality & presence of complications are not contraindications for vats. all cases are administered perioperative albendazole ( mg twice a day, administered for three cycles of days each, with a gap of days in between) which helps in preventing recurrence and also takes care of any inadvertent intra-operative spillage. introduction: minimally invasive surgery (mis) is the standard approach for most of the surgical procedures performed by general surgeons. traditionally the majority of operations for trauma are performed open due to the complexity of the cases, however, trauma surgeons are expanding their armamentarium to include mis in a variety of acute procedures. we report our experience with the application of laparoscopy in a variety of trauma cases. methods: a retrospective review of trauma cases performed between / - / . during that time laparoscopic cases were performed after traumatic injury. patient demographics, injury severity (iss), injury mechanisms, the types of procedures and outcomes will be described. means and standard deviations were calculated and t test were performed. a p value of . was statistically significant. results: demographics-a total of trauma cases were performed laparoscopically during the study period. the majority were male, n= and the age was sd . obesity was documented in %, hypertension or cad was in %, and substance abuse was in %. blunt trauma was in % and penetrating %. the iss was sd . surgical procedures-the majority, %, of the procedures were completed laparoscopically. non-therapeutic laparoscopy was performed in %. repair of diaphragmatic or traumatic abdominal wall hernias were %. hematoma evacuation and control of bleeding was %. control of solid organ bleeding and repair was performed in %. intestinal repair occurred in %. for the cases that required open conversion iss was sd vs. laparoscopic cases iss was sd , p= . . outcomes: the overall length of stay was days sd . there was n= late death in a poly-trauma patient that required open conversion for complex solid organ and intestinal injuries. there was n= case of a community acquired pneumonia, and n= case of a recurrent pneumothorax. conclusions: a descriptive series of trauma operations approached with mis techniques is described. this cohort had high injury severity and a predominance of comorbid conditions. laparoscopy was successfully applied in the majority of cases for a variety of therapeutic procedures and mortality and morbidity was low. mis is safe and is gaining momentum for application in traumatic injury. objectives: laparoscopic distal gastrectomy for early gastric cancer is a standard treatment in japan described in guidelines. the surgical procedure has been shifting from laparoscopic assisted to complete laparoscopic surgery. in this study, we evaluated the outcomes and safety of the laparoscopic assisted distal gastrectomy. methods: for the marking of the oral side transecting line, the clipping at oral side of cancer lesion was performed by gastro-endoscopy before surgery. the lymph node dissection (d +/d ) is performed laparoscopically. as the dissection of the pancreatic superior region, the assistant hold the left gastric artery and keep the good view by retracting the pancreas. the common hepatic artery and proximal side of splenic artery are exposed. both sides of the left gastric artery and vein are exposed. left gastric vein and left gastric artery are cut after clipping and sealing. lymph node dissention of hepato-duodenal ligament is done and right gastric artery is cut after clipping and sealing. minor curvature of upper gastric wall is exposed (no , dissection). billroth i reconstruction by the circular stapler (cdh) is performed. through the upper median incision with cm, operator pulls out the stomach and transects the oral side of stomach with linear stapler after palpating the clips. duodenum is transected after purse string suture. gastroduodenal anastomosis is performed by cdh. results: two hundred cases were analyzed. the operation time, blood loss and the conversion to open surgery rate were minutes, ml, and . %, respectively. as postoperative complications, anastomotic failure, pancreatic fistula and postoperative bleeding were %, . % and %, respectively. the reoperation rate was %. one surgical death due to cerebral infarction was experienced. there were no patients with ppm (pathological proximal margin) positive and too much pm distance. frequency of abdominal wall incisional hernia and ileus were % and %, respectively. conclusion: although there is the disadvantage that small laparotomy can be made in the upper abdomen, laparoscopic assisted distal gastrectomy with billroth i reconstruction in our procedure is enough good from the viewpoint of the precision of proximal margin, and the incidence of serious complications. introduction: minilaparoscopy (mini) is a modality of minimally invasive surgery that attempts to produce less surgical trauma to the abdominal wall by reducing the diameter of surgical instruments to mm. searching for better outcomes in inguinal hernia repair, surgeons have looked for new and less invasive alternatives such as single-incision surgery, single-port surgery and mini. minilaparoscopic transabdominal preperitoneal hernia repair (mini-tapp) demonstrates some of the known advantages of mini general surgery procedures such as enhanced visualization, improved dexterity and great cosmetic outcome. it is safe and reproducible since it does not differ from standard laparoscopy. introduction: the celiac plexus is a structure located in the retroperitoneum, at the level of the lumbar vertebra, which is located in the prevertebral region and has sympathetic fibers. patients with advanced gastrointestinal cancer and associated pain, one of the management strategies is pain control. neurolysis of the celiac pleural by laparoscopy was first reported in humans in in patients with advanced pancreatic adenocarcinoma with excellent results. experience will be shown in the simplification of the technique for the procedure. method: neurolysis of the celiac pleura was performed in patients with advanced gastrointestinal cancer, stomach %, pancreas % liver % other %, no complications associated with the procedure, pain improvement was achieved in % of patients after process. the standardization of the technique by laparoscopy and its simplification, has made this procedure that is replicable and safe. description of the technique: patient in french position, technique of trocars, umbilical trocar mm and trocars of mm paraumbilical, staging laparoscopy is performed and sampling if necessary, is identified in the region of the lowercurvature of the stomach, the celiac trunk and the emergence of the left gastric artery are identified and cc of % alcohol diluted to the medium in the lateral fatty bearing are instilled through a pericranial under direct vision, verifying the non-arterial instillation of the alcohol. there were no complications related to the procedure. results: we report the experience of one group who underwent celiac pleura neurolysis in patients with advanced gastrointestinal cancer, gastric cancer %, pancreatic cancer %, liver cancer % and another %. the most frequent pathology report was adenocarcinoma, % of the patients were managed at hours with sustained effects, up to months of follow-up. with a significant decrease in pain medication. only patient required new laparoscopic neurolysis because of difficult-to-manage pain. the operative time of this procedure was minutes. the standardization of the technique, the use of low cost inputs, makes this type of procedure easily replicable with goodresults in pain management in cancerpatients. conclusions: mis is offered as one of the fundamental tools for the management of palliative procedures in gastrointestinal cancer. neurolysis of the celiac pleura with standardization of the technique, use of low cost elements, and the surgeon's skills make this procedure an option of management and control of pain in patients with advanced gastrointestinal cancer, is easily replicable, economical and insurance. background: the non-absorbable polymer clip offers a solution to the disadvantage of traditional metallic clip. due to its metallic property, it is not only expensive but also causes artifacts on imaging studies and often migrates into cbd. this study compares the traditional standard metallic clip with hem-o-lock used in laparoscopic cholecystectomy (lc) in regard of the safety and efficacy?. material and methods: this study includes patients who underwent lc implementing metallic clip (mc) and patients implementing hem-o-lock clips (h )?. both clips were applied to cystic duct and artery, then the gallbladder was dissected from the liver bed by diathermy. the intraoperative and postoperative parameters were collected including duration of the operation and complications?. results: the median operative time was not statistically different between the mc and the hc group ( . vs . minutes, respectively; p= . ) with no significantly less incidence of bile spillage ( vs. , p= . ) . no statistically significant difference was found in the incidence of postoperative complications between both groups ( vs. , p= . ). no postoperative bile leakage was encountered in both groups. conclusion: hem-o-lock clip provides a complete hemobiliary stasis and a secure cystic duct and artery control. its cost effectiveness is also attractive while provides efficacy equivalent to that of the standard metallic clip. introduction: most of the blunt thoracoabdominal injury patients always have multiple organ injuries. plan of definite treatment depends on the preoperative diagnosis. in isolating diaphragmatic traumatic injury without others organ injury laparoscopic approach is helpful, decrease a length of hospital stay as well as decrease a wound complication. authors describe the laparoscopic treatment of the patient who had rupture of a diaphragm from blunt trauma in an emergency setting. methods and procedures: a years old man presented with motor vehicle accident and mechanism of injury was blunt thoracoabdominal injury. he complains about chest tightness and tachycardia. complete evaluation and ct scan ware performed. stomach was herniated to the left chest and diaphragmatic ruptured was found neither others great vessels nor solid organs injury. the laparoscopic approach was desired and left diaphragm was repair by non-absorbable sutured without intraoperative complication. results: the patient has been discharged days post-operative with full recovery. chest x-ray was taken before discharge, in out-patient department weeks as well as months after discharge which shown no diaphragmatic herniation. conclusion(s): laparoscopic approach in isolated traumatic ruptured diaphragm patients is safe and should be considered. short-term outcome of laparoscopy-assisted distal gastrectomy with roux-en-y reconstruction through mini-laparotomy for gastric cancer since , we have introduced laparoscopy-assisted distal gastrectomy (ladg) with b-i reconstruction through mini-laparotomy. regarding to reconstruction, roux-en y reconstruction are also one of the choice in ladg, however, the technical feasibility has not been well documented so far. the purpose of this study was to compare the short-term outcome of ladg with roux-en-y reconstruction through mini-laparotomy compared to that of ladg with b-i anastomosis. between and , patients who underwent ladg for gastric cancer in oita university were enrolled in this retrospective study. since , the roux-en-y reconstruction has been performed as a standard method in our department. these patients were divided two groups based on anatstomosis; roux-en-y (r-y) group (n= ) and billroth i (b-i) group (n= ). baseline characteristics, operative results (including complications) and pathological results were evaluated. there were a considerably greater number of patients with advanced clinical stage and having ≥t invasion in the r-y group. estimated blood loss was lower in r-y than in b-i (p. ) and operative time was longer in r-y than in b-i (p. ). there were no significant differences in all grade intra-operative complications (p= . ). in addition, there were no significant differences in all grade post-operative complications between the two groups except internal hernia. hospital mortality was % in each group. ladg with r-y reconstruction through mini-laparotomy was technically feasible as well as ladg with b-i anastomosis. utilization of laparoscopy associated with blunt abdominal trauma: the nationwide inpatient sample - kenneth w bueltmann , marek rudnicki ; advocate illinois masonic medical center, chicago, il, university of illinois introduction: the incidence of trauma and its heavy burden upon the healthcare system remain strong. paradigm shifts in the management of these cases has, however, improved the mortality in such cases. it can be expected that improvements in management, when combined with the benefits of laparoscopy, will demonstrate positive impacts upon treatment outcomes. methods: the nationwide inpatient sample was referenced for inpatient stays for the years to . abdominal trauma cases were selected and identified as hollow (ho) or solid organ (so) type, and as blunt or penetrating. the trauma subset was then scanned for the presence of discrete laparoscopic procedures, laparotomy, and converted cases, and flagged accordingly. conclusion: utilization of laparoscopy in treatment of intraabdominal solid and hollow organs injury increases over time. although current analysis based on available hcup nis data include any procedures done during post-traumatic hospitalization, its results can lead to conclusion that minimally invasive technique is being utilized in increased fashion. introduction: single incision laparoscopic (sil) surgery is a laparoscopic procedure which leaves a single small incision in navel, and has been reported to be less invasive than and as safe and efficient as the conventional multiport laparoscopic (mpl) surgery. the long-term rate of incisional hernia after sils colectomy is unknown, and the risk factors of incisional hernia formation is not fully elucidated. methods and procedures: this is a retrospective from a prospectively collected database. the investigation took place in a high-volume multidisciplinary tertiary private hospital in japan. introduction: laparoscopic approach in the acute surgical care setting continues to be underutilized. we aim to report the successful diagnostic and therapeutic use of laparoscopy in the management of a nontoxic patient presenting with acute abdomen and to highlight the benefits of a minimally invasive approach without added morbidity. case report: presented is a -year-old male with history of cad s/p cabgx two years prior and no abdominal surgical history who presented to the ed with sudden onset severe, diffuse, abdominal pain of six-hour duration with n/v. there was no trauma to the abdomen. he had mildmoderate hypertension, but was otherwise hemodynamically stable. on examination, the patient was in severe distress and writhing in pain. fast exam was unable to be performed secondary to pain. cta of the abdomen revealed mesenteric abnormalities with associated small bowel edema in the rlq suspicious for small bowel ischemia. he was taken to the or for diagnostic laparoscopy. he was found to have an omental adhesive band to the abdominal wall with herniation of the small bowel through the small opening. approximately cm of ischemic, nonviable small bowel was resected and anastomosed intracorporeally. he tolerated the procedure well and was discharged home on post-operative day . discussion: primary omental related internal herniation of small bowel is exceedingly rare. there have been only few cases reported in the literature ( , , , ) . two were diagnosed on exploratory laparotomy, one on diagnostic laparoscopy and one at autopsy. the one who underwent diagnostic laparoscopy did not require bowel resection. in presenting this case, we hope to illustrate the role of laparoscopy in the management of acute abdominal pain due to bowel compromise. introduction: morgagni hernias are a rare finding in the adult population, and represent - % of all congenital diaphragmatic hernias. multiple approaches to these rare hernias have been described in the literature. here we present a novel technique of laparoscopic trans-abdominal repair using a combination of the endo-close device (medtronic, minneapolis, mn) and the ti-knot (lsi solutions, victor, ny.) methods: in a patient with a large left anterior diaphragmatic defect we performed trans-abdominal suturing utilizing the endo-close to perform primary closure of the defect, using the ti-knot to secure the pledged sutures along the anterior fascia. due to the size of the defect ( cm) this primary repair was buttressed with polyester mesh. in a second patient with a smaller ( cm) classic right-sided anterior diaphragmatic defect we similarly performed laparoscopic trans-abdominal suturing using the endo-close to traverse both the anterior and posterior fascia and the ti-knot to secure the sutures in order to perform a primary repair of the hernia. both patients presented had an uneventful postoperative course and no indication of recurrence at months. conclusions: morgagni hernias present unique technical challenges. in our experience the combined use of trans-abdominal suture with laparoscopic knot replacement device allowed for completion of both cases laparoscopically with minimal tension on the repairs. feasibility of concomitant laparoscopic splenectomy and cholecystectomy in situs inversus totalis: first case report worldwide ibrahim a salama, md, phd; department of hepatobiliary surgery, national liver institute, menoufia university introduction: situs inversus totalis is a rare anomaly characterized by transposition of organs to the opposite site of the body. combined laparoscopic splenectomy and cholecystectomy in those patients is technically more demanding and needs reorientation of visual-motor skills. presentation of case: herein, we report a year old girl presented with yellowish discoloration and left hypochondrium and epigastric pain diagnosed as hereditary spherocytosis (hs). the patient had not been diagnosed as situs inversus totalis before. the patient exhibit a left sided "murphy's sign" and spleen palpable in right hypochondruim. diagnosis of situs inversus totalis was confirmed with ultrasound, computerized tomography (ct) and magnetic resonant image (mri) with enlarged right sided spleen and presence of multiplegall bladder stones with no intra or extrabiliary duct dilatation. the patient underwent combined laparoscopic splenectomy and cholecystectomy as treatment of hereditary spherocytosis (hs). discussion: feasibility and technical difficulty in diagnosis and treatment of such case pose challenge problem due to the contra lateral disposition of the viscera. difficulty is the laparoscopic technique encountered in skelatonizing the structures in calot's triangle, which consume extra time than normally located gall bladder with right sided standing surgeon and the position changed to left sided standing surgeon during splenectomy. in review up to date medical literature this is the first case reported worldwide. conclusion: provided that the technique is performed by an experienced surgical team, concomitant laparoscopic splenectomy and cholecystectomy in situs inversus totalis is a safe and feasible procedure and may be considered for coexisting spleen and gallbladder disease as in hereditary spherocytosis (hs) as changes in anatomical disposition of organ not only influence the localization of symptoms and signs arising from a diseased organ but also imposes special demands on the diagnosis and surgical skills of the surgeon. objective: to identify the preference among medical students of the following surgical approaches: open surgery, conventional laparoscopy, minilaparoscopy (mini), single incision laparoscopic surgery (sils), natural orifice transluminal endoscopic surgery (notes), and robotic surgery. methods: an online google questionnaire was filled by medical students of different years in medical school. before answering the questionnaire, they watched an online video showing the different techniques, its advantages and disadvantages. the questionnaire consisted of questions about the hypothetical situation where the participants were going to be submitted to an elective cholecystectomy and they could decide which technique they would prefer. all statistical analysis was performed using the r software program, version . . . the chi-squared test was performed for categorical variables where appropriate. a p value . was statistically significant. results: one hundred and eleven medical students answered the survey. ( . %) were female and men. most of the students were between to years old ( . %). they were in the first four years of medical school. when asked if they would consider notes or single incision even if they know that they are new procedures and with not completely established security standards, . % ( ) answered that they wouldn´t consider with no difference between gender (p= . ). when asked if only conventional laparoscopy, robotics or mini were offered, which one they would choose: % of women and . % men chose mini first (p= . ). about the factors that they would consider the most important when choosing the surgical technique, they answered safety first ( . %), followed by the surgeon´s experience with the procedure ( . %), with no statistically significant result between genders (p= . ). when asked if they would consider an open technique even with the other techniques available and compared according to their year in medical school, students closer to finishing medical school would not consider it, with a statistically significant result (p= . ). regarding the most important factors they would consider and compared by year in medical school, safety and experience of the surgeon performed best, with a statistically significant result (p. ). conclusion: among the available surgical approaches, minilaparoscopy tends to be the preference among women medical students who considered safety the most important aspect. the closer they get to the end to medical school, the less they consider the open technique. background: extension of the single incision for the purpose of specimen removal in singleincision plus one additional port laparoscopic surgery (sils+ ) can undermine the merits of sils + , either by increasing wound-related morbidity or by destroying cosmesis. methods: we retrospectively analyzed the clinical outcomes of patients underwent elective sils + anterior resection, either with transanal specimen extraction (tase, n= ) or transumbilical specimen extraction (tuse, n= ), for colorectal cancer from january to june . this study included patients with a tumor diameter less than cm, measured by preoperative computer tomography. results: both groups were similar in patient's basic information and oncologic condition. most surgical data and postoperative clinical variables were comparable between tase and tuse group, except for increasing operative time in tase ( . + . vs. ± . min, p= . ) and reducing wound complications in tase ( % vs . %, p= . ). dosage requirement of narcotic analgesics was not inferior in tase group compare to tuse group. no significant differences were observed in conversion rate, perioperative and overall morbidity between the two groups. conclusion: although sils+ with tase prolonged operative time compare to with tuse, implement of tase is expected to provide benefit of reduced wound-related morbidity in patients with a tumor diameter less than cm. medhat ibrahim, md; al-azhar university, naser city, cairo, egypt purpose: morgagni hernia (mh) is a rare condition. mh is less than % of surgically treated diaphragmatic hernias in infants. there is no specific symptom for the maorgagni hernia. open surgical repair was the golden stander before the introduction of the laparoscopic surgery in the children and infant. there are many different laparoscopic techniques for mh repair have been reported. i report laparoscopic repair of mh in five infants using primary sutures closure with inrta-corporeal knot tying and ethicon secure strap device. this study is an evaluation of the safety and efficacy of this new laparoscopic technique of mh repair in infants with it is short-term outcomes follow up. patients and methods: five infants with mhs underwent laparoscopic repair by hernia sac excision then two primary sutures, non-absorbable proline through the full thickness of the anterior abdominal wall and the posterior rim of the defect, intra corporeal sutures knot tying, ethicon secure strap device which was used to complete the colures of the defect. there was no insertion of chest tube or drain. results: five infants with mh were operated upon. there were males and female. all cases were left side mh, male-female ratio was : . intraoperative and postoperative analgesia requirement was minimal (paracetamole mg/kg/rectal suppository/ hours for the first hours). ceftriaxone mg/kg single dose at the anesthesia induction. all operations were completed laparoscopic. all infants started and tolerated oral regular feeding with in hours from surgery. none of the patients developed intraoperative or postoperative complications. the maximum follow-up was months (mean, months). all patients are in good health without recurrence or port site compilation. conclusion: this easy save technique of mh repair is reducing the operative time and postoperative hospital stay. it is minims the need of postoperative analgesia, anti biotic. the early oral feeding is also a good benefit. the introduction: transumbilical single port laparoscopic appendectomy (tspla) is the most popularized single port surgery in the world. it provides more cosmetic benefits than conventional laparoscopic surgery. however, single port appendectomy requires longer operation time and advanced surgical skills. we aimed to investigate the learning curve for tspla. material and methods: data were collected from patients who underwent tspla by single surgeon between march and february . the learning curve were analyzed using a cumulative sum control chart (cusum) for operation time and complication. results: a total of patients were included in this study. mean operation time is . ± . minutes. there was no open or multi-port conversion. based on cusum for operation time, learning curve were cases. conclusions: tspla is a safe and effective alternative procedure. the learning curve could be overcome safely without major complications. our results suggest that the cases are sufficient to achieve surgical skills for tspla. introduction: anastomotic leakage (al) is a life threatening complication after minimally invasive ivor lewis esophagectomy (tmie ile) and has diverse treatment strategies such as conservative treatment, endoscopic treatment and surgery. however, there is no consensus on which treatment strategy is best. the aim of this study was to analyse various therapeutic strategies for al and their outcomes. methods and procedures: this retrospective multicentre study was performed in three highvolume hospitals. all patients that developed al after tmie ile in the period of january -july were included. the different endoscopic (stenting, clipping and suction-drainage) and surgical treatments and their success-rate were described; success was defined as clinical improvement after primary treatment. primary endpoint was the time until oral feeding was resumed. secondary endpoints were hospital stay and the total amount of surgical, endoscopic and radiologic interventions. results: in total patients that developed al were identified; four patients received antibiotics only. in the remaining patient, endoscopic treatment was performed as primary treatment in %; % received primary surgical treatment. basic variables were similar in these groups. median postoperative day of diagnosis of al was day in the endoscopic-group and day in the surgical-group (p= . ). admission to the icu as a result of the leakage was necessary in % in the endoscopic-group versus % in the surgical-group (p. ). however, median icu-stay was significantly shorter in the endoscopic-group ( days versus days, p= . ). success-rate of the primary treatment was similar; % and % respectively (p= . ). primary and secondary endpoints were comparable for both the endoscopic-and surgical-group; median time until oral feeding was resumed was days and days respectively (p= . ), median total hospital stay days and days respectively (p= . ) and the median number of interventions was in both groups (p= . ). conclusion: endoscopic treatment appears to be a safe and efficient therapy for al after tmie ile. a patient-tailored approach based on the condition of the patient and the morphology of the leak can be adapted to avoid surgery in a selection of patients. this may prevent surgical reoperations and reduce icu admissions. background: lymph node (ln) dissection around recurrent laryngeal nerve (rln) is one of the most important and difficult procedure in esophageal cancer surgery because of high rate of ln metastasis and risk of rln palsy. especially around left rln, the surgical area is far and narrow by thoracic approach which tends to results in insufficient ln dissection. therefore, we tried to remove this ln by imaging lymphatic chain to dissect sufficient ln. surgical procedure: we perform thoracoscopic esophagectomy by semi-prone position using - mmhg thoracic air pressure. after dissection of right rln ln, middle and lower esophagus, encircle the esophagus at the level of bifurcation of bronchus and pull toward right side by tape to dissect the dorsal and left side of upper esophagus. dissect the tissue including left rln ln from trachea by pulling esophagus up to dorsal side and try to move this tissue toward dorsal side of left rln so that this rln ln tissue can recognize as the "lymphatic chain". to increase the mobility of esophagus, cut the esophagus at the level of aortic arch and pull further up this upper esophagus to dorsal side. cut the esophageal branch of rln and separate this lymphatic chain from rln. at the end of thoracic procedure, this lymphatic chain is attached to upper esophagus. after the upper esophagus has pulled out from cervical site, lymphatic chain can easily recognize at the esophageal wall. result: we performed this lymphatic chain procedure in cases. to evaluate this procedure, cases of conventional method by same prone positioned esophagectomy was used for control. there was no statistical difference between these two groups in amount of blood loss (lymphatic chain: conventional= ml: ml, p= . ), rate of rln palsy ( . %: . %, p= . ). although the thoracic operation time was extended in some degree ( min: min, p= . ), number of dissected ln was increased ( . : . , p= . ) and recurrence along left rln has been relatively fewer by this method ( . %: . % p= . ). conclusion: ln dissection around left rln would be easy and sufficient by imaging lymphatic chain. further improvement is needed to secure this procedure and further evaluation should be done to support this data. introduction: to evaluate the role of robotic assisted surgery as part of an appropriate patient work-up and treatment of ipmn and its consistency in terms of perioperative and long term results. few reports described singular minimally invasive procedures for ipmn. this study aims to describe a comprehensive, oncologically adequate treatment of ipmn in a minimally invasive unit with an extremely high robotic penetrance. methods and procedures: we retrospectively analyze our database of resected ipmn between and . this case series includes consecutive, unselected patients: all candidates with a preoperative diagnosis of ipmn were approached robotically. results: among robot assisted pancreatic resections, we identified patients with ipmn. one was excluded for having less than months follow-up, so patients were included and analyzed. they underwent duodenopancreatectomy in cases, distal pancreatectomy in cases and central pancratectomy in . all but one indications followed the most updated available guidelines (sendai from to and fukoka from to ; american gastroenterology association guidelines were used for comparison only). one patient was operated even if the guidelines were suggesting to follow up, because of a strong familiar cancer history. the final pathology for this patient was high grade dysplasia. in another patient we were inside fukoka's recommendations, but outside aga guidelines and the final pathology was adenoma in chronic pancreatitis. postoperative morbidity was . ( low grade complications, one grade a pancreatic fistula, now considered a biochemical leakage only) and mortality was zero. one conversions to open surgery occurred only: a dp in jehowah's witness with a bulky mass behind the portal vein. the mean follow up was months (range: - ), with only one loss to follow up after months for a high grade dysplasia. conclusion: in hepatobiliary pancreatic minimally invasive centers the treatment of ipmn can be grant following the same principles of major cancer centers, with comparable results. large unbiased studies are needed to evaluate if a minimally invasive approach could modify the ratio between operated and surveilled patients. reducing the use of catheters, tubes and imaging after hiatal hernia surgery significantly reduces length of hospital stay sophia s oswald, candice l wilshire, md, brian e louie, md, ralph w aye, md, alexander s farivar, md; swedish medical center introduction: historically, standard post-operative management of patients undergoing laparoscopic hiatal hernia surgery has been placement of a foley catheter and nasogastric tube (ngt) at the time of surgery with removal early on postoperative day (pod) one, at which time an upper-gastrointestinal series study (ugi) would be performed. we initiated a quality improvement project, seeking to assess if we could safely forego placement of foley and ngt along with the ugi, unless clinically indicated. our aim was to determine if this decreased overall length of stay (los), and how often and which demographic of patients needed placement of foley or ngt postoperatively. methods and procedures: we reviewed patients who had undergone laparoscopic hiatal hernia surgery between and under a single thoracic surgeon. patients were excluded for poor esophageal motility (peristalsis \ %), previous esophageal surgery, and presence of a paraesophageal hernia (peh) with over % of the stomach contained in the chest. eligible patients were further stratified into two groups: fast track and non-fast track. fast track was defined as patients who left the operating room (or) with no foley or ngt, and did not receive a routine ugi on pod one. non-fast track was defined as patients who left the or with a foley and ngt and received a routine ugi on pod one. los was measured in hours from the start of surgery to the time of discharge. results: of the patients included, were categorized as fast track and as non-fast track. the two groups were similar in terms of age, gender, bmi and asa; however, the fast track group had fewer paraesophageal hernias and shorter surgery times [table] . the hospital los, however, was significantly shorter in the fast track group, even though there were more postoperative urinary catheters utilized. no patients in fast track group needed an ngt placed or ugi ordered during initial stay. conclusion: in more straightforward laparoscopic hiatal hernia surgery, surgeons can safely forego ngt and foley placement, as well as ugi evaluation the following morning. these initiatives may translate to a quicker discharge from the ward, and may allow safe transition to performing these cases in hour ambulatory outpatient setting. further evaluation of additional interventions and patient education to decrease los are underway. the conclusion: laparoscopic surgery seems to be a safe and feasible option, with long-term benefit for primary tumor resection with metastatic colorectal cancer, but optimal treatment has yet to be defined. the canadian association of gastroenterology (cag) has implemented the colonoscopy skills improvement (csi) program across canada with a goal of improving colonoscopy quality. the programs' efficacy has not yet been formally assessed. this retrospective cohort study was performed on fourteen endoscopists practicing in a tertiary referral center who have undergone csi training between october and december . procedural data were collected before and after csi training. data were extracted from the electronic medical record (emr) and entered into spss version . for analysis. student's t-test was used to compare groups for continuous data; chi-squared tests were used for categorical data. data were collected for a total of procedures; were done before csi training and procedures since csi training. our sample size provided % power to detect a mean difference in adr improvement of %. the most common indication for colonoscopy was family history of colorectal cancer in ( . %) patients. while age ( . yrs v. . yrs, p. ) and gender ( . % male v. . % male, p= . ) were similar, they were statistically different between groups. groups were comparable in terms of indication, and completion rate ( . % v. . %). adr improved significantly after completing the course ( . % v. %, p. ). an improvement was also noted in both polyp detection ( . % v. . %, p. ) and polyp removal ( . % v. . %, p\ . ). we have seen a significant increase in adr at out institution since implementing the csi program. gastric stomach cancer is a rapid major cause of cancer-related death globally, have higher incidence in men and it is noticeable by its heterogeneity. a lot of studies have expressed out the molecular basis of this cancer, include pathogenesis, invasion and metastasis. the invention of new technologies has help to bring out several novel biomarkers that have diagnostic and prognostic value. therefore, this review centers on biomarkers for the early diagnosis, treatment and prognosis of gastric cancer, elaborate the clinical important of serum tumor markers in a patient with this cancer as well as checking the growths, prognosis together with epigenetic changes and genetic polymorphisms. a deep and rigorous search was carried out in pub med/medline using specific words; "gastric cancer", with "tumor marker". our search yielded important reports about related topic from books and articles that were published before the end of september . conclusively, scientists are utilizing time and resource to salvage this nemesis which is of global burden. classical and novel biomarkers are important for treatment as well as pre-post diagnosis of gc. major causes for this disease are cigarette smoking, infection by helicobacter pylori, atrophic gastritis, male sex, and high salt intake. the treatment of which early diagnoses is of important to the management, after pathological diagnoses by stage prognosis and metastatic setting, although the outcome proved not so good includes chemotherapy, and oral medication are oxaliplatin, capecitabine, cisplatin and -fluorouracil ( -fu). introduction: emergent appendectomy is the standard of care in usa based on tradition rooted in theory that delaying surgery allows for progression of disease and poorer outcomes. antibiotic treatment alone has been shown feasible in the treatment of uncomplicated appendicitis. in clinical practice surgical treatment can be delayed due to a multitude of medical and logistical reasons. this study evaluates the relation between timing of surgery to outcomes. methods and procedures: consecutive adult patients undergoing appendectomy in a teaching community hospital were risk stratified using the acs risk calculator. time from imaging to incision defined early and delayed groups. statistical analysis was used to determine association between risk level, timing of surgery and outcomes. results: % of patients in this study were considered high risk. average time to incision was . hours. shorter time to incision was associated with a statistically significant lower length of stay (p. ). for every hours in surgery delay, one day was added to the length of stay. no statistical difference was found between time to incision and other outcome variables of clinical complications, conversion to open appendectomy or frequency of complicated appendicitis. length of stay was longer than predicted by acs risk calculator in both high and low risk groups. a multidisciplinary, obesity-focused approach improves diagnosis of obesity-related illnesses: a new paradigm for the care of patients with obesity roderick olivas, aaron brown, md, racquel s bueno, md, cedric s lorenzo, md; university of hawaii -department of surgery introduction: patients suffering from the burden of obesity are at significant risk for medical problems that lead to premature death and disability. we hypothesize that a multidisciplinary bariatric team will be better equipped to recognize and diagnose these conditions. this study hopes to quantify that a patient focused approach leads to increased recognition of obesity-associated comorbidities, thus improving quality of care and surgical outcomes. methods and procedure: a retrospective medical chart review of patients who underwent bariatric surgery from / / to / / was performed comparing patient problem lists obtained from their primary care providers upon entry into the bariatric program, and the final problem list generated after evaluation by the program's multidisciplinary team. the total number and specific comorbidities identified before and after multidisciplinary team evaluation was analyzed with a paired t-test and manova, respectively. comparison of the number of comorbidities identified against specific patient demographics was conducted using paired t-test. results: a total of patient charts were selected and met inclusion criteria. the sample consisted of % women and % men; the mean age was . ; the mean bmi was . ; % were morbidly obese (bmi ) and % were obese . the total number of comorbidities identified after evaluation by a multidisciplinary team was significantly greater (p=. ), with the average number of comorbidities diagnosed before and after being . and . , respectively. a significant increase (p. ) in the identification of comorbidities before and after evaluation were noted for all demographics, and no disparities regarding gender, age, marital status, employment status, bmi, or ethnicity where identified. conclusion: patients with obesity unknowingly suffer from many obesity-associated comorbidities simply because their health care providers have failed to recognize the existence of these conditions. surprisingly, this include diseases that are highly associated with obesity, such as osa and t dm, for which obese patients should be screened. although the root of this dereliction is yet to be determined, insufficient obesity-focused education and inherent weight bias among providers must be considered. assessment by a multidisciplinary bariatric team resulted in the identification and treatment of an increased number of comorbidities in this patient population. increased recognition of obesity-related comorbidities improves quality of care, which can translate into improved surgical outcomes. introduction: it is known that surgical residents suffer from sleep deprivation. no recent study evaluated the type and number of calls received at night. lately, burn out, depression and suicide have been the subject of interest in studies and media because of the higher rate among the residents compared to general population. the objective of our study is to evaluate junior resident's level of fatigue and the quantity and quality of calls received during on-call nights in general surgery at chus. methods and procedure: transversal study conducted on junior residents that were on-call in general surgery at the chus between april and august , . the participants detailed all the calls received between pm and am on an database created on the application handbase and completed a daily calendar of their on-call night noting all the tasks they did every half hour (surgery/consultation/sleep). the level of fatigue was evaluated at the end of the night at am with a visual analog of sleep scale on a score over points. results: the level of fatigue / (tired) or / (exhausted) was reached in closed to % of the oncall nights. the median number of calls by night was and the median duration of sleep was only . hours. the median lenght of uninterrupted sleep was . hours by night. among the total nights and calls analyzed, % were ''not pertinent'' and % were ''reportable in the morning''. more than % of the nights had at least one call ''not pertinent'' or ''reportable in the morning'' that have interrupted the junior resident's sleep. the level of fatigue was significantly correlated to the number of calls received during the night (spearman's rho=+ . , p. ) and to the number of uninterrupted hours of sleep (spearman's rho=− . , p. ). conclusion: the level of fatigue is very high among the junior residents in general surgery. many of the calls received during the night are not pertinent or could have been delayed to the morning. our results lead us to the conclusion that interventions and recommendations should be made to raise nurses and resident's awareness about the situation to reduce the unnecessary calls and the level of fatigue of the residents. we hope that on-call resident sleep will be better preserved and that will result in fewer health issues for them (burn out, depression, suicide). without interruptions: does twitter level the playing field? heather j logghe, md , laurel milam, ma , natalie tully, bs , arghavan salles, md, phd ; thomas jefferson university, washington university, introduction: frequent interruption of women in conversation has long been noted anecdotally, and studies confirm that women are interrupted more often than men. such interruptions can diminish perceptions of authority and compromise women's self-confidence. on twitter, users cannot be interrupted in the same way they can be in live conversation. thus the platform may provide a means for women to overcome this obstacle. to determine the degree to which women surgeon leaders utilize twitter compared to their male colleagues, we examined the twitter accounts and activity of the leaders of three national surgical societies. methods and procedures: lists of surgeons holding leadership positions in three surgical societies; the american college of surgeons, the academic association of surgery, and the society of american gastrointestinal and endoscopic surgeons, were obtained and duplicate names were deleted. table details the organizations and leadership positions included. the twitter accounts of these leaders were then identified and confirmed by reviewing the accounts for surgical content. account duration was calculated from the join date. the number of tweets, accounts following, followers, and likes were recorded for each account. outliers were defined as two standard deviations from the mean. results: one hundred sixty-eight men and women surgeon leaders were identified. forty-nine percent of the men and % of the women were found to have twitter accounts. mean account durations for men and women were similar, . years and . years, respectively. outliers for total tweets ( men, women), accounts following ( men), followers ( men), and likes ( men) were excluded from analyses. almost all positive outliers were men. there were no negative outliers. overall, excluding the outliers, there were no significant differences between men and women in any metric. conclusion: among leaders in the surgical organizations analyzed, a higher percentage of women than men have twitter accounts. those with the greatest number of tweets, accounts following, followers, and likes, however, are overwhelmingly male. thus, although women in this sample were more likely than the men to have twitter accounts, men were more likely to gain influence through their accounts. increasing women's influence in this public forum may position them as much-needed role models for the current and next generations. surgical societies may help reduce the disparity in women's representation in surgical fields through education of their members on how to use social media. introduction: the aim of this study was to report the perioperative morbidity and short-term outcomes of a case series of robotic-assisted laparoscopic transabdominal preperitoneal (tapp) inguinal hernia repairs. methods and procedures: a retrospective review (january through december ) of patients who underwent either unilateral or bilateral robotic-assisted laparoscopic tapp inguinal herniorrhaphy by two attending surgeons was performed. patient demographics, perioperative morbidity, operative time, and follow-up data were analyzed. results: patient demographics are summarized in table . mean operative times for unilateral and bilateral inguinal herniorrhaphy were . ± . and . ± . minutes, respectively. mean robot console times for unilateral and bilateral inguinal herniorrhaphy were . ± . and . ± . minutes, respectively. postoperative complications included urinary retention ( . %), conversion to open repair ( %), and delayed reoperation ( . %). no major bleeding, surgical site infection (ssi), or mortality was observed. at first follow-up visit ( ± days), symptoms/signs included groin/scrotal swelling ( %), seroma ( %), groin pain ( %), burning ( %), numbness ( %), and persistent urinary retention ( %). % of patients required a second follow-up visit. two patients underwent reoperation for suspected recurrence but instead a cord lipoma was found without a hernia defect. conclusions: robotic-assisted tapp inguinal herniorrhaphy can be performed with operative times and short-term outcomes similar to those published for open technique. the robotic-assisted tapp inguinal herniorrhaphy is a safe and an efficient minimally invasive surgical option with lower ssi risk and better cosmetic results. gunnar nelson, nathan lau, phd; virginia polytechnic institute & state university introduction: the fundamentals of robotic surgery (frs) and fundamentals skills of robotic surgery (fsrs) are universal curriculums covering a range of topics to assure a high level of surgical skills for optimal patient outcomes. this assurance of skills should include management and response to adverse events. thus, we reviewed frs and fsrs to identify any gaps in educational contents pertaining to how surgical teams are trained to handle adverse events in robotic surgery. methods and procedures: we conducted a literature search through google scholar, journal of robotic surgery, and plos one on frs and fsrs from to . we reviewed articles on preparing medical professionals in handling adverse events during robotic surgeries. besides the two curriculums, we also surveyed the literature on the characteristics of the adverse events and responses of the medical team. this literature survey provided a basis for recommending additional education contents to frs and fsrs. results: in our review, the frs contains modules consisting of an introduction to robotic surgery, with cognitive, psychomotor, and team training/communication skills. meanwhile, the fsrs contains different tasks, half of which on human-machine interaction and another half on operative interaction. both curriculums appear to lack contents on managing adverse events in robotic surgery. according to fda data, , adverse events were reported per , surgeries, of which (i) % relates to broken pieces of surgical instruments falling into patients, (ii) . % pertains to burning holes in tissue from electric arching, and (iii) . % relates to unexpected operations of the instrument such as power outage and issues with electrosurgical units. thus, medical professionals should be trained to manage common adverse events in robotic surgery. for frs, augmenting the five current scenarios in the communication section with common adverse events (i.e., broken pieces falling into patients) would minimize complications under abnormal circumstances. for fsrs, the most logical method would be augmenting the operative interaction tasks with adverse events to train medical professionals. conclusion: we discovered universal curriculums on robotic surgery lack education contents for training medical professionals to manage adverse events and out of the , procedures, ( . %) pertained to device malfunction. to protect the patient's health, universal curriculums must incorporate contents preparing medical professionals in responding to adverse events, particularly device malfunctions, during robotic surgeries. introduction: this retrospective study was performed to evaluate the safety and feasibility of the new senhance robotic system (transenterix) for laparoscopic cholecystectomies. we report the first single-institutional experience utilizing this new robotic platform. methods: approximately robotic cholecystectomies were performed using the senhance robotic system. the senhance surgical system is a new robotic platform that consists of a cockpit, manipulator arm and a connection node ( figure ). this new system provides robotic surgery with numerous advantages including eye-tracking camera control system, haptic feedback, reusable endoscopic instruments, and a high configuration versatility due to total independency of the manipulator arms. patients were between and years of age, eligible for a laparoscopic procedure with general anesthesia, had no life-threatening disease with a life-expectancy of less than month and a bmi\ . a retrospective review of a variety of prospectively collected pre-, peri-and postoperative data including but not limited to patient demographics, intraoperative as well as postoperative complications was performed. cholecystectomies were performed by expert level laparoscopic surgeons. results: the standard laparoscopic technique and setup was easily applicable to the senhance robotic system for this particular surgery. operative time and perioperative complications were comparable to reports of standard laparoscopic cholecystectomies. there was no significant learning curve detected in our case series. conclusion: we report the first experience with laparoscopic cholecystectomies using the new senhance robotic system. there were no major perioperative complications and operative time was comparable to standard laparoscopic cholecystectomies well reported in the literature. this case series suggests that the senhance robotic system can be safely and easily used for laparoscopic cholecystectomies by experienced laparoscopic surgeons. background: the ergonomic benefits or robotic surgery for the health of the surgeon are widely touted as benefits of this technique, though concern remains over a perception of increased risk of injury to patients, particularly in the novice robotic surgeon. injury to the bedside surgeon and assistants due to robotic movement can also occur, though not previously reported. we describe a finger fracture to the bedside surgeon due to entrapment between robotic arms and discuss potential risks to the surgeon in robotic procedures. procedure: a distal pancreatectomy and splenectomy was performed utilizing the davinci si system (intuitive surgical, inc., sunnyvale, ca). during the operation, hemorrhage was encountered which required an instrument exchange that was delayed by self-testing failures. after the instrument was validated and advanced into the field by the bedside surgeon, the operator abruptly took control of the device to reposition. the external portion of the active arm was then rapidly and forcefully propelled laterally toward a stationary retracting arm. the bedside surgeon's hand was still engaged on the instrument being inserted and became trapped between the two arms, leading to a right middle finger crush injury. results: the bedside surgeon sustained a fracture to the distal phalanx at the insertion of the flexor tendon with significant hyperextension of the joint. there was temporary paresthesia of the fingertip. while flexor tendon function was preserved and surgery was not required, the surgeon was required to maintain continuous splinting and was unable to return to full duty for a total of weeks. the surgeon has mild residual hyperextension. conclusions: while complications to the patient have previously been attributed to the robotic platform, this case demonstrates that there are other inherent hazards to members of the operative team. as is natural with all indirect visual surgical techniques, the operator becomes intensely focused on the internal view and instruments in the field. this spatial separation is accentuated on the robotic platform as the isolated console provides a complete visual field immersion, no tactile feedback, and a disconnect between the rapid, sizeable outward arm motions need to produce small internal movements. given the need for maximum dexterity internally, the device doesn't have external proximity sensors to prevent arm-arm or arm-operator collisions. while many bedside operators report anecdotes of collisions with the device, this case reveals the forces involved at the human-machine interface can lead to more significant injuries. robtic approach to non-midline abdominal wall hernias: a single institution experience from a high volume center emily benzer, do, j. stephen scott, md, facs; university of missouri introduction: the objective of our study was to evaluate our experience with robotically repaired non-midline abdominal wall hernias at a high-volume robotic surgery program. we also will discuss the technical advantages of the use of robotic technology in repair of these unusual hernias which have typically had higher recurrence rates then midline hernias. laparoscopic approach for lateral ventral abdominal wall hernia (spigelian) and lumbar hernia has been described, however the success of robotic assisted repair for these hernias has yet to be determined. methods: a retrospective case analysis of all robotic abdominal hernia cases between june and june at an academic institution with a single high volume robotic surgeon was performed. the operative details of robotic repair of non-midline abdominal hernias, patient demographics, length of stay and smoking status were recorded and analyzed. the technical advantages of the use of robotic technology for example circumferential fixation of the mesh, ease of intracorporeal suturing, and the use of wristed instruments to gain better angles for posterior fascial release were evaluated. results: a total of cases were identified. the average age of the patients was . years (range - years) and patients were predominantly female ( %). spigelian hernias represented % (n = ) and lumbar hernias % (n= ). all patients had primary closure of their defect and patients ( %) had a posterior myofascial release performed. mesh types placed included polypropylene uncoated (n= ), polypropylene coated (n= ), and biologic (n= ). with uncoated polypropylene mesh placed had peritoneum closed over the mesh. the average length of stat was . days (range - days). there were no recurrences identified over a mean follow up period of . months (range . - . months). conclusion: robotic assisted repair of non-midline abdominal wall hernias is a viable option in the elective setting with no recurrences noted in this case series. the technical advantages of using robotic technology were identified and discussed in detail. these advantages theoretically improve outcomes in these patients however further analysis on long-term outcome and costs will have to be determined in future studies. the inguinal hernia repair has seen several critical improvements in recent times due to the implementation of new techniques, including laparoscopic repair, as well as robotic repair. with over , inguinal hernia repairs performed annually, it is important to identify the safest and most patient-friendly method. for surgeons, robotic assisted laparoscopic surgery is gaining in popularity for its dexterity and d visualization. but despite the growing interest in robotic hernia repairs, there is a scarcity of literature to support its superiority over open inguinal hernia repair. this study hypothesizes that patients who undergo robot assisted laparoscopic inguinal hernia repair will have decreased immediate post-operative pain, shorter recovery room stays, decreased narcotic requirement, and overall decreased pain at follow up compared to open inguinal hernia repair. in this study, we performed a retrospective analysis of patients who underwent either an open or robotic assisted laparoscopic inguinal hernia repair at stamford hospital, from july -july . the following characteristics were analyzed for both subsets of patients: gender, bmi, type of repair, operative time, recovery room time, immediate post-operative pain, and post-operative pain at follow up. our study demonstrated longer average operative time for patients undergoing robotic hernia repair compared to open repair, which was statistically significant (p value=. ). patients who underwent robotic inguinal hernia repair spent less time in the recovery room compared to patient who underwent open repair. in addition, patients in the robotic hernia group required less narcotics in the recovery room compared to patients who underwent open repair (p value = . ). there was no statistically significant difference between lengths of hospital stay between the two groups. this study highlights several possible advantages of robotic inguinal hernia repair, including lower post-operative pain scores, less narcotic usage required in the post-operative period, as well as shorter recovery room time. the results from this study should increase interest in investigating the superiority of robotic inguinal hernia repair. future plans for study involve comparing robotic to laparoscopic repair. in addition, we plan to continue to follow the study patients to look at additional qualitative metrics, including time to return to work and time to return to daily activities. introduction: buccal mucosal grafts (bmg) are traditionally used in urethral reconstruction. there may be insufficient bmg for applications requiring large amounts of graft, such as urethral stricture after gender affirming phalloplasty. rectal mucosa is an alternative with less post-operative pain, no impairment in eating and speaking, and larger graft dimension. laparoscopic transanal minimally invasive surgery (tamis) has been described by our group. due to the technical challenges of harvesting a sizable graft within a confined space, we adopted a new approach using the intuitive da vinci xi® system. we demonstrate the feasibility and safety of a novel technique of robotic tamis (r-tamis) in the harvest of rectal mucosa for the purpose of onlay graft urethroplasty. methods and procedures: irb approval was obtained. three female-to-male transgender adults (age range: - years) presenting with post-phalloplasty urethral strictures underwent robotic rectal mucosal harvest. the procedure was first rehearsed on an inanimate model using bovine colon. the surgery was performed under general anesthesia with the patient in lithotomy position. the gelpoint path transanal access platform was used. the rectal mucosa was harvested by the robotic instruments after submucosal hydrodissection. specimen size harvested correlated with clinical surface area needed for urethral reconstruction. following specimen retrieval, flexible sigmoidoscopy was used to ensure hemostasis. the rectal mucosa graft was placed as an onlay for urethroplasty. results: there were no intraoperative or postoperative complications. average graft size was cm (range: - cm). every case had excellent graft take for reconstruction. all patients recovered without morbidity or mortality. they reported minimal postoperative pain and all regained bowel function on the first postoperative day. all reported significantly less postoperative pain and greater quality of life in comparison to prior bmg harvests. the procedure has been refined to increase efficiency and decrease operative time by maintaining adequate insufflation, retraction of the mucosal graft, and maintaining graft integrity. conclusions: to our knowledge, this is the first use of r-tamis for harvest of rectal mucosal graft. our preliminary series indicates the robotic approach is feasible and safe. it constitutes a promising minimally-invasive technique to employ in urethral reconstruction. demonstrated feasibility and avoidance of the challenging recovery associated with bmg harvest warrants further application and long-term evaluation of this procedure. prospective studies evaluating graft success, donor site morbidity and long-term outcomes are needed. introduction: the proportion of robotic minimally invasive procedures that are being performed annually is growing rapidly, specifically in the field of general surgery. a robotic approach to minimally invasive procedures potentially confers a number of benefits ranging from a magnified viewing field to greater attenuation and translation of hand movements leading to improved stability and maneuverability. it is paramount that a robust curriculum is designed for training surgical residents in robotic techniques. the aim of this project is to assess the current state of robotic surgery training at the ohio state university, with specific regard to whether it is currently temporally effective in addition to establishing a baseline against which the robotic surgery curriculum can be compared. methods and procedures: data were obtained for cases performed at the ohio state university hospital east, between january and september of . case time, date, type, and attending surgeon were recorded and tracked for review. of the cases, were cholecystectomies, were unilateral inguinal hernia repairs, and were bilateral inguinal hernia repairs-for a total of procedures included in the analysis. chief residents were trained in two-month blocks, beginning in january of . mean console operative times for the first and second months were compared for cholecystectomies as well as unilateral and bilateral inguinal hernia repairs. results: mean console time decreased for cholecystectomies (− . %; n= ), bilateral (− . %; n= ) and unilateral (− . %; n= ) inguinal hernia repairs from month one to month two. there was a large amount of variance across training blocks, but there was a systematic improvement in operative time across the training period. average operation length was shortest for cholecystectomies (m= . min), followed by unilateral inguinal hernia repairs (m= . min), and finally bilateral inguinal hernia repairs (m= . min). discussion: this preliminary data suggests that residents are able to decrease their robotic operation time over the course of the two-month rotation. although sample sizes were relatively small for each block, the consistency of the trend supports this conclusion. further data collection will allow for more precise estimates in the future, and stronger conclusions to be drawn. these results show that rapid improvement is possible and provide motivation to establish robotic surgery curricula for general surgery residents nationally. robotic pancreas-sparing treatment of pancreatic neuroendocrine tumors: three case reports and review of the literature alessandra marano, giorgio giraudo, stefano giaccardi, desiree cianflocca, diego sasia, felice borghi; santa croce e carle hospital introduction: pancreas-sparing resections would be the ideal procedure in case of small pancreatic neuroendocrine tumors (p-nets) reducing the risk of exocrine and endocrine insufficiency. compared to standard resection, this type of surgery is safe and feasible without increasing the risk of postoperative complications except the overall rate of clinical pancreatic fistula (pf), which did not result in higher mortality or overall morbidity. robotic surgery for pnets enucleation has been rarely described but initials experiences have shown that this approach is associated with favorable outcomes. the aim of this study is to describe three cases of dv®si™ pancreatic enucleation for p-nets located in the uncinate process, in the body and in the posterior aspect of the tail of the pancreas, respectively. a brief review of the literature regarding the application of robotics for pnets enucleation is also included. methods and procedures: this study includes patients undergoing dv®si™ enucleation for pnets with a maximum diameter no more than cm and a distance between tumour and main pancreatic duct (mpd) greater than mm. at surgery, exposure of the pancreas was achieved by separation and traction of the gastrocolic and gastropancreatic ligaments. the pancreas was explored: an intraoperative ultrasound was used ensuring negative margins and leaving the mpd intact. thus, a cross-stitch through the tumour was made routinely in order to pull the tumour. enucleoresection was carried out with monopolar scissors and bipolar forceps. the tumour was placed into a specimen bag and removed from the trocar port. a drain was always left. results: median total operative time was min. no conversion neither intraoperative complications occurred. median length of stay was . days. two patients presented a pf grade a (classification isgpf) while a pf grade b occurred in case of pancreatic tail net enucleation. final pathology revealed two insulinomas and one non-functioning net of the pancreatic body. at a median follow-up of months no pancreatic insufficiency, reoperation or tumour reoccurrence was observed in all cases. the robotic approach for the treatment of p-nets is safe and feasible and, in selected cases, it may extend the indications of minimally invasive pancreatic-sparing surgery. in particular, the robotic approach provides a more precise dissection and may ensure negative margins and the mpd intact. these preliminary results are consistent with literature data about over robotic pancreatic enucleations for p-nets that shows favourable surgical outcomes, especially if compared with those of open surgery. introduction: rectal cancer continues to be a surgical challenge. new technologies must be incorporated into practice and, at the same time, oncologic surgery and overall outcomes must be improved. the use of da vinci robotic surgery systems has spread rapidly in the field of rectal cancer treatment showing several technical advantages and favorable outcome compared to laparoscopy. since the introduction of the robotic platform in our institution in , we have adopted a single-docking robotic technique for rectal resection. the aim of this study is to present our standardized technique and to analyse the clinical outcomes of the first robotic rectal procedures. methods and procedures: prospectively collected data reviewed from consecutive patients who underwent single docking totally robotic (da vinci® si™) dissection for rectal cancer resection between june and august under eras program. robotic rectal surgery was performed without changing the position of the robotic cart but only the robotic arms are repositioned between two phases: ) vascular ligation, and sigmoid colon to splenic flexure mobilization; and ) pelvic tme. results: there were men ( %) and the median age was years (range- - ). thirty-five patients had neo-adjuvant chemoradiotherapy whilst patients had bmi [ . procedures performed included anterior resection (n= ) and abdominoperineal resection (n= ). protective ileostomy was performed in patients. the median operating time was min (range- - ). there was one conversion and two intra-operative complications (one bladder lesion and one ureteral lesion, respectively). median length of stay was . days (range, , and readmission rate was %. thirty-day mortality was zero. anastomotic leak rate was %, and all patients except by one were managed conservatively. the mean lymph node harvested was (sd± . ). radial margin was negative in all patients. at median follow-up of months, there were no local recurrences. the single docking robotic technique is a safe and feasible approach for rectal surgery: in our study it has demonstrated favourable clinical outcomes and the adoption of a standardized stepwise approach was useful especially during the initial learning phase. to the best of our knowledge, this is the largest series from italy to report this standardized approach and the short-term clinical and oncological outcomes. in the complex laparoscopic surgical procedure, there is a problem such as that the laparoscope and the surgical instruments interfere with each other because multiple instruments is concentrated in one place. this problem is significantly appear in the laparoendoscopic single site surgery. therefore we suggested multi degrees of freedom (dof) manipulator with mantle tube for assisting laparoendoscopic surgery, which manipulator has two flexion and one telescopic mechanisms actuated by wire. it is possible to insert any thin surgical instruments such an endoscope the mantle tube of the multi dof manipulator, which the manipulator can let those surgical instruments access the operative field from different axis with other instruments. the use of this manipulator has two advantages, one of which is avoidance of fighting between instruments and laparoscope. the other is that become possible to ensure a satisfactory field of vision in the operative field. in this report, we assumed that this multi-dof manipulator is used as laparoendscope. in order to evaluate the performance of this manipulator, the operation time of the test in the abdominal cavity simulator (fasotec inc.) was measured. the test is a contact test to multiple-targets, which is a test that bring a forceps contact multiple-targets in the abdominal cavity simulator according to the defined pattern. as a general comparison and evaluation target for this measurement result, it is compared with the case using the same access method as the conventional rigid endoscope. in this test, the number of contacts between forceps and laparoendoscope were recorded by using electrical device. subjects (n= ) are adult men who trained the peg transfer in the above simulator. it was compared of total operating times of the test and the field of vision obtaining each device. from these results, using the suggested manipulator device rather than using rigid laparoscope a satisfactory field of vision is obtained, and it is possible to short the operating time approximately seconds, and to small the number of contacts significantly. therefore it was shown that the effectiveness using the suggested manipulator device. for this reason, use of this device is expected to facilitate the complex surgical operation. additionally, it is performed para ablative operation of swine liver tissue in the abdominal cavity simulator, as previous step of clinical test. the operative field in this test was surveyed, the refinements of this manipulator for improvement performance were described in this report. yoshiyuki usui, md, phd, ichiro akiyama, md, phd, hironori kunisue, md, phd, hideaki mori, md, phd, tetsuya ota, md, phd; okayama medical center background and methods: we have performed approximately cases of gasless endoscopic thyroid surgery since for years. this surgery was performed through a small subclavian incision and using a wire traction and inserting an endoscope. we have modified and improved our surgical techniques by inventing various surgical instruments. here we introduce four newly invented surgical instruments, chronologically. results: we made u-retractor ( ), u-trocar ( ), u-kelly forceps ( ), and u-suction tube retractor ( ). all surgical instruments were modified from conventional surgical instruments. the u-retractor was a piercing retractor, each end of which had a sharp tip and a retractor. this retractor was inserted from the -cm working port outside the body and retracted the muscles effectively. the u-trocar was reversely set from inside to outside to make the working space wider. the u-kelly forceps which had a special ratchet were made to dissect loose connective tissue around the thyroid gland avoiding injury of the recurrent laryngeal nerve. the u-suction tube retractor facilitated a wider working port and eliminated the mist created by the ultrasonically activated scalpel effectively. recent data showed no difference of operative time, hoarseness, blood loss and hospital stay between conventional thyroid lobectomy and gasless endoscopic lobectomy. conclusion: gasless endoscopic thyroid surgery has been improved in the last years. this procedure made the excision of not only benign thyroid tumors but also small thyroid carcinomas. this operation is still cost effective, because almost all surgical instruments are reusable and is a satisfactory experience to both the patients and surgeons. objective: to put forward the importance of complete (r ) resection for the treatment of retroperitoneal tumors increasing overall survey. methods: in this study; patients having the diagnosis of retroperitoneal tumors with different histopathological subtypes whom were hospitalized in emergency surgery department of istanbul medical faculty between the years of and were evaluated retrospectively. the database of the department was analyzed. operational backgrounds, histopathological results, radiological evaluations, and assesments about relapses, and overall survey were obtained from the medical archieve. results: the average follow-up time was , years. all of the patients included into the study were undergone operations. the average time of hospital stay was calculated as days. of the patients were found to have positive surgical margins in their histopathological evaluations. overall mortality rate of the study was % ( / ). we have observed a direct correlation between complete (r ) resection and disease-free survival. patients having relapses had worse prognosis in terms of overall survey ( % mortality rate). after having done the statistical evaluation, surgery was found to be the main determining factor for the assesment of overall survey. conclusion: reference to an experienced and multidisciplinary surgical center after an early diagnosis has upmost importance for the treatment of retroperitoneal tumors. surgical approach constitutes the main element in the management. overall survey is directly correlated with complete (r ) resection. novel fluorescent dyes for real-time, intraoperative, organ-specific visualization of biliary and urinary systems using dual-color near-infrared imaging ; children's national health system, nih/nci p multidisciplinary approach for management of necrotizing pancreatitis: a case series prabhu senthil-kumar university of alberta, centre for the advancement of minimally invasive surgery introduction: the objective of this study was to systematically review the bariatric surgery literature to understand how weight loss is reported. the incidence of obesity has increased globally. according to the world health organization more than million were obese in . in the last decade, bariatric surgery has been increasingly utilized as an effective treatment option for severely obese patients. currently, bariatric surgeries are among the most commonly performed operations. the primary outcome of such procedures is weight loss which has been shown to vary according to the type of surgery. however, there are different methods used to report weight loss which makes it difficult to directly compare outcomes between studies. a previous review by dixon et al. in revealed a wide heterogeneity in weight loss reporting. however, there have been no recent reviews on the reporting of weight loss in bariatric surgery. methods: a search of the medline electronic database was performed for studies published in using search terms gastric bypass/sleeve gastrectomy, weight, human, and english. articles were selected by two independent reviewers based on the following inclusion criteria: ( ) adult participant ≥ years predictive factors for excess body weight loss after bariatric surgery in japanese obese patients takeshi naitoh hypertension resolution after rapid weight loss: a single institution experience cristian milla matute reoperative bariatric surgery: analysis of indications and outcomes: a single center experience iman ghaderi objective: to observe the effects of duodenal-jejunal transit on glucose tolerance and diabetes remission in gastric bypass rat model. method: in order to verify the effect of duodenal-jejunal transit on glucose tolerance and diabetes remission in gastric bypass, twenty-two type- diabetes sprague-dawley rat model established through high fat diet and low dose streptozotocin (stz) administered intraperitoneally were assigned to one of three groups: gastric bypass with duodenal-jejunal transit (gb-djt n= ), gastric bypass without duodenal-jejunal transit (rygb n= ) and sham (n= ). body weight, food intake, blood glucose, as well as meal-stimulated insulin, and incretin hormones responses were assess to ascertain the effect of surgery in all groups. oral glucose tolerance test (ogtt) and insulin tolerance test (itt) were conducted three and seven weeks after surgery. results: comparing our gb-djt to the rygb group, we saw no differences in the mean decline in bodyweight, food intake, and blood glucose -weeks after surgery. gb-djt group exhibited immediate and sustained glucose control throughout the study outcomes with sham operation did not differ from preoperative level. conclusion: preserving duodenal-jejunal transit does not impede glucose tolerance and diabetes remission after gastric bypass in type- diabetes sprague-dawley rat model is bariatric surgery effective for comorbidity resolution in super obese patients? methods: a retrospective analysis of outcomes of a prospectively maintained database was done on obese patients with a diagnosis of at least one or more of the following comorbidities-t dm, htn, osa, or hld-at the time of initial visit who had undergone either a sleeve gastrectomy (sg) or a roux-en-y gastric bypass (rygb) at our hospital between and . the patients were stratified based on their preoperative body mass index (bmi) class: bmi methods: we retrospectively reviewed all patients that underwent laparoscopic sleeve gastrectomy (lsg) at our institution from - . common demographics and comorbidities were collected as well as creatinine, preoperatively and up to hours after surgery. the renal function was calculated using the ckd-epi formula, derived and validated by levey et al. acute kidney injury was defined as an increase in serum creatinine by ≥ . mg/dl within hours after surgery. all tests were two-tailed and performed at a significant level of . . statistical software r, version . . ( - - ) was used for all analyses. results: of the patients reviewed conclusion: the impact of laparoscopic sleeve gastrectomy in renal function is evident within the first hours after surgery. patients undergoing lsg, especially patients with baseline chronic kidney disease stage ≥ are at increased risk of developing acute kidney injury in the perioperative setting the body mass index (bmi), fasting plasma glucose (fpg), glycosylated hemoglobin (hba c), serum triglyceride, serum cholesterol and blood pressure of all patients were measured before and at months after surgery. the results were collected and analyzed. results: patients suffered from metabolic disease undertook lsg surgery successfully (a mean age of years), were male and were female. all of patients suffered from obesity and the mean bmi of them was . ± . kg/m before surgery. among them, patients had type diabetes mellitus (t dm), patients had hypertriglyceridemia (htg), patients had hypercholesterolemia (hc) and patients had hypertension. the mean bmi of patients at months after surgery was . ± . kg/m and decreased significantly (p. ). the mean excess weight loss (ewl%) of patients was . %± . %( %* %) at months after surgery. the average levels fpg, hba c of t dm patients at months after surgery were . ± . mmol/l, . %± . % methods: we retrospectively reviewed all patients who underwent bariatric surgery from to . we assessed kidney function using the chronic kidney disease epidemiology collaboration (ckd-epi) and cardiovascular risk using framingham risk score (frs) equation pre-operatively and at and months of follow-up. our population was divided into two groups: patients with ckd stage ≥ (gfr\ ml/min) and patients with normal gfr. significance. results: of the , patients reviewed, . % (n= ) met the criteria for ckd-epi glomerular filtration rate (gfr) and framingham risk score (frs) calculations. after matching, patients ( . %) were left to analyze, % (n= ) of which had a laparoscopic sleeve gastrectomy. eighty-six patients ( %) had an impaired kidney function (ckd≥ ) (group ) and patients ( %) had a normal gfr (group ). common demographics and comorbidities after matching are described in table . the mean creatinine in group was . ± . mg/dl versus . ± . mg/ dl in group (p
). glomerular filtration rate was . ± . ml/min in group and ± . ml/min in group . furthermore, when the frs was calculated at months follow-up, patients with impaired kidney function had an absolute risk reduction of . % corresponding to a relative risk reduction (rrr) of group . the percentage of estimated bmi loss was found to be similar in both groups ( . ± . and . ± . respectively p= . ). conclusions: bariatric surgery, especially lsg, has a positive impact on kidney function particularly in patients with chronic kidney disease stage or greater. despite these patients having a higher preoperative cardiovascular risk, they showed similar risk reduction when compared to patients with normal kidney function at months of follow-up the impact of socioeconomic factors and indigenous status jerry t dang only ( . %) patients underwent urgent conversion for management of complications after sg. three patients had intraoperative complications necessitating blood transfusion. fourteen ( . %) patients required readmission within days postoperatively. six patients ( . %) required surgical interventions including for gastrointestinal leak, for hemodynamic instability, for a cecal perforation, and for a small bowel obstruction. there were no mortalities within the first year of revisional surgery. in patients with bmi[ kg/m at the time of revisional surgery, at the median postoperative follow-up of (interquartile range, - ) months, a median (interquartile range, - ) kg/m reduction in bmi was observed. overall, ( . %) patients had persistent type diabetes at time of revisional surgery. improvement of diabetes was observed in patients ( . %) after conversion of sg to rygb. among patients with gerd symptoms, subjective symptomatic relief was reported at the last follow-up. conclusion: weight recidivism is the most common indication for revision of sg objective: to evaluate laparoscopic mini-gastric bypass in the treatment of morbid obesity. method: three hundred patients with a mean bmi of . . kg/m underwent a laparoscopic mini-gastric bypass between to . a laparoscopic approach with five trocar incisions was used to create a long narrow gastric tube; this was then anastomosed ante-colically to a loop of jejunum cm. distal to the ligament of treitz peri-operative and short-term follow-up results up to does age or preoperative bmi influence weight loss after bariatric surgery? one-way anova or the kruskal-wallis test was used to compare continuous data across all groups. subsequent analysis of categorical data was achieved by chi-square or fisher's exact test. statistical significance was accepted as p. . results: a total of patients ( % male) were analyzed. average age and preoperative bmi were . ( . ) years and . ( . ) kg/m , respectively. preoperative comorbidities included: diabetes ( . %), hypertension ( . %), hyperlipidemia ( . %), previous myocardial infarction ( . %), obstructive sleep apnea ( . %), chronic obstructive pulmonary disease ( . %), gastroesophageal reflux ( . %), tobacco use ( . %). the asa classes of patients undergoing sg were ii ( . %), iii ( . %), and iv ( . %). the follow up rate at , and months was . %, . %, and . %, respectively. the -day mortality and readmission rate were % and . %, respectively. the %ewl was not different among age groups at , or months for the total, male, or female cohorts. among preoperative bmi groups, %ewl was not different in any cohort at or months, but was different at months for the total cohort (p. ) and female cohort (p\ . ), and trended toward significance in the male cohort (p= . ). the highest %ewl was found to be in patients with preoperative bmi of - . there was no difference in -day mortality or readmissions among groups a crp≥ mg/dl had a sensitivity for a complication of % and a specificity of %. primary bariatric surgery patients with a post-operative complication had higher crp levels compared to those who did not ( . ± . mg/dl vs . ± . mg/dl; p= . ). there was no difference in crp levels for patients with a -day reoperation or readmission. there were no mortalities. conclusions: bariatric surgery patients with elevated post-operative crp levels are at increased risk for -day complications. the low sensitivity of a crp≥ mg/dl suggests that a normal crp methods and procedures: the patients, who formed the previously published cohort, were contacted and their charts were reviewed. follow-up visits, symptom severity scores, and any subsequent medical or surgical interventions were collected. symptoms were assessed using the symptom severity score (sss) and the gastroparesis cardinal symptom index (gcsi) questionnaires. success was defined as a sss of or less. results: out of original patients, patients ( males, females) were available for follow-up ( patients declined participation, were lost to follow-up, patient was deceased, and was excluded after undergoing esophagectomy for unrelated indication) mbbs ; grant government medical college and sir jj government hospitals methods and procedures: twenty-six nh patients with dm were prospectively randomized to undergo either lrygb or lsg. patients were followed for -years with primary end points consisting of total weight loss (twl), percent excess body weight loss (%ebw) and impact on dm as measured by fasting blood glucose (fbs) and hba c. in addition, baseline, week, and , , , , and months post-operative levels of glucagon-like peptide (glp- ), peptide yy (pyy), leptin, and ghrelin were collected. results: a total of / patients completed follow-up. the %ebw at year for lrygb and lsg were % and %, respectively. resolution of dm occurred in / patients, the remaining three subjects were in the lgs arm. pre-operative fbs in lrgyb and lsg groups, were and , respectively. pre-operative hba c in the lrygb and lsg groups, were . and . , respectively. fbs at year for lrygb and lsg were and , while hba c for lrygb and lsg were . and . , respectively. a consistent post-operative decrease in fbs was only seen in lrygb. lrygb ghrelin percentages increased at , , and months, while levels decreased in lsg. leptin percentages decreased in both groups. the ppy levels remained relatively unchanged in both groups. lrygb glp- levels increased at week, , , and months. lsg glp- trends were similar except at months where glp- levels decreased. conclusion: lrygb and lsg resulted in equivalent post-surgical weight loss and resolution of dm in the nh population video assisted thoracoscopic thymectomy (vats) has emerged as a minimally invasive alternative to the standard transsternal approach. we present herewith the surgical and neurological outcomes after vats their operative time, blood loss, conversion rate and post operative parameters like intensive care unit (icu) stay, inter-costal drainage (icd) indwelling time, hospital stay were recorded. neurological outcomes were assessed based on myasthenia gravis foundation of america (mgfa) post intervention status classification. statistical analysis was done using stata software. results: ninety patients underwent thoracoscopic thymectomy during the study period. vats was done through right approach in ( . %), left approach in ( %) bilateral approach in patients ( %) and subxiphoid approach in ( . %). there was conversion to open approach in ( . %) patients due to dense adhesions at westchina hospital of sichuan university were included. all of the operations were performed by a single skilled surgeon. we divided our patients into two groups based on whether isao was used. of them, patients received isao for lps and patients received lps without isao. surgical skills and safety were evaluated. results: there were no significant differences in preoperative patients characteristics of the two groups. significantly less intraoperative blood loss( . ± . ml vs . ± . ml; t=− . , p= . ) were observed in group of isao conclusions: isao is technically feasible, safe surgical skills for patients reveived lps, and its represents an effective method to decreased intraoperative blood loss. p modular laser-based endoluminal ablation of early cancers: in-vivo dose-effect evaluation and predictive numerical modelling giuseppe endoscopic submucosal dissection enables en-bloc removal of early gastrointestinal neoplasms. however, it is technically demanding and time-consuming. laser-based ablation (la) techniques, are limited by the lack of depth penetration control and thermal damage (td) prediction. our aim was to evaluate a predictive numerical modelling (pnm) of the td to preoperatively select the optimal power and exposure time enabling a controlled ablation down to the submucosa (sm). additionally, the ability of confocal endomicroscopy (ce) to provide information on the td was assessed at the histology, there was an increased damage depth per higher j applications. the r value at . j was . ± . , and was significantly lower when compared to energies from j (r= . ± . ; p. ) up to j ( . ± . ; p\ . ). safe m and sm ablations were achieved applying lower p settings ( . and w), at different t values, leading to an mp impairment only in and % of the cases, respectively. ce provided relevant images of the td, consisting in architecture's distortion and disappearance of the gland's contours. the predicted damage depth we also analyzed early gastric cancer patients who received lpg-ip with cm jejunal interposition. anastomosis procedure was overlap method for eshophagojejunostomy and gastrojejunostomy, feea for jejuno-jejunostomy. results: the comparison between otg/opg-ip shows no significant difference in perioperative complications and qol scores, significant smaller body weight loss in opg-ip group. lpg-ip group also shows good result in short term outcomes. consideration: as comparison in open surgery implies superiority in jejunal interposition, we have introduced lpg-ip. esophagogastrostomy after proximal gastrectomy is simple but has a risk for sever gerd symptoms, no optimal procedure for reconstruction after proximal gastrectomy has yet been established. although laparoscopic jejunal interposition is relatively complicated in procedure, we can safely perform in combination with common anastomosis techniques. conclusion: body weight loss in otg-ip group is smaller compared to otg group consecutive patients with early gastric cancer underwent solo spdg (n= ) and mldg (n= ) performed by same surgical team. solo spdg can be defined as practice in which a surgeon operates alone using camera holder. mldg usually requires two or three surgical assistants. the inclusion criteria in this study were (i) pathologic proven stage i-ii gastric cancer (ii) no other malignancy (iii) more than d lymph node dissection (iv) r surgery. one-to-two propensity score matching was performed to compensate for the differences between two groups. results: after the propensity score matching, solo spdg (n= ) and mldg (n= ) patients were selected. mean operation time ( ± . vs ± . mins, p= . ) and estimated blood loss (ebl) ( . ± . vs . ± . ml, p= . ) were significantly lower in the solo spdg group than in the mldg group. the hospital stay and the use of pain control were similar between the two groups. although the initiation of semi fluid diet was similar, the time to first flatus was earlier in the solo spdg adhesional omental hernia: a case report an unexpected cause of small intestinal obstruction in crohn's disease strangulation inguinal hernia due to an omental band adhesion within the hernia sac: a case report omental adhesion, intestinal herniation, and unexpected death in the elderly small bowel obstruction secondary to greater omental encircling band-unusual case report the median operative time was min. the median postoperative hospital stay was . d. histological examination of the tumors revealed carcinomas, adenomas, and carcinoid. complications occurred in ( %) patients, viz., ssi (two patients), pancreatic fistula (two patients), bleeding (two patients), passing failure (one patient), and cholangitis (one patient). however, no severe postoperative complications (clavien-dindo classification grade or higher) were reported in these cases. conclusion: our cases showed that duodenal tumor resection using lecs enables curability through a minimally this study aimed to compare the outcomes of tltg with those of latg by using a meta-analysis. methods: we searched pubmed, embase, and cochrane library in may, to locate prospective or retrospective studies on surgical outcomes of tltg versus latg. the outcome measures were postoperative complications such as anastomosis leakage and anastomosis stenosis, operation time, blood loss, time to flatus, time to first oral intake, and postoperative hospital stay endoscopic thyroid lobectomy: our early experience at tertiary care hospitals of lahore univariate analysis was performed followed by logistic regression to identify independent predictors for the primary outcome. results: forty-six out of ( %) patients referred for gp required jt insertion to treat malnutrition. etiology of gp included: % idiopathic, % diabetic, % post-surgical. thirty-six patients ( %) reported severe daily symptoms. twenty-five patients ( %) had successful return to oral intake while ( %) required prolonged feeding access, reinsertion of a jt or tpn initiation. on multivariate analysis patients who had a pyloroplasty (p= . , or . ) and those who were married (p= . , or . ) were found to be independent predictors of successful discontinuation of tube feedings. on subgroup analysis -hour gastric emptying time normalized after pyloroplasty (p= . ) in patients which had a successful re-initiation of oral intake while persistent gastric emptying refractory to pyloroplasty was associated with failure. the group of patients who underwent pyloroplasty did not differ in terms of demographics, marital status (p= . ) and preoperative gastric emptying (p= . ) from those who did not. gp etiology (p= . ) psychiatric conditions (p= . ) and substance abuse laparoscopic transabdominal repair of morgagni hernia rebekah macfie average procedure length was . minutes. average hospital length of stay was . days, with all patients tolerating a regular diet prior to discharge. our -day readmission rate was / ( . %). / ( . %) patients required repeat egd evaluation for either recurrence of symptoms or impacted food bolus. at week follow-up, / patients ( %) complained of dysphagia and / patients ( %) had eliminated ppi from their daily medication regimen. at month follow-up, / patients ( %) complained of dysphagia and / patients ( %) had eliminated ppis. at year follow-up, / patients ( %) complained of dysphagia and / patients ( %) had eliminated ppis. conclusion: as a recently introduced surgical option, no long-term data exists detailing the linx procedures ultimate success rates and complication profile mini-laparoscopic vs traditional laparoscopic cholecystectomy: preliminary report deniz atasoy since the introduction of minilaparoscopic cholecystectomy (mlc) in , it gained little interest that could be attributed to decreased durability of the reduced size instruments, poorer optical resolution and smaller jaws of the instrument tips. our aim was to compare the outcomes of mlc with traditional laparoscopic cholecystectomy (tlc) one developed choledocholithiasis on postoperative day one and after ercp the course was uneventful. the other patient developed choledocholithiasis and acute pancreatitis on the sixth postoperative day and was treated conservatively. the stone in the ampulla had fallen by itself without a need for ercp single-incision plus one additional port laparoscopic surgery for colorectal cancer with transanal specimen extraction: a comparative study two patients had a previous attempt of hernia repair, one with mesh. one patient did not have any immunosuppression due to hiv infection, whereas the other were on cyclosporine, tacrolimus and/or mycophenolate mofetil. there were two laparoscopic and two open cases, mean operative time was . minutes ( - ), mean blood loss was ml ( - ). mesh used were biological porcine dermis in one case, polypropylene with absorbable hydrogel barrier in three cases. mean mesh length and width were cm ( - ) and . cm ( - ) respectively. one patient underwent a component separation, though none of the patients had the fascial defect closed. there were no intra-operative complications. three patients were readmitted for hyperkalemia, abdominal pain, and seroma respectively. neither recurrences nor reoperations were reported. mean follow-up was . days ( - ) conclusion: post liver transplant incisional hernia repair is feasible either laparoscopic or in an open fashion. because of the size and location of the defect, fascial closure is unlikely achievable. the use of standard techniques and materials give a similar result of the non-transplant population. p technique of esophagojejunostomy using orvil after laparoscopy assisted total gastrectomy for gastric cancer shinichi sakuramoto there was a significant difference in mortality between the two time-periods, / patients died during - and / died during - (p= . ). those who died were significantly older ( years ( - )) than the survivors ( y ( - )) (p= . ). five of the patients who died in the previous group died without any intervention. / of those who had an acute open necrosectomy died. surgical necrosectomy correlated significantly with mortality (p= . ). the only patient who died in the recent group died without any intervention. none of the patients receiving minimal invasive drainage in this group died until now only cases in adults and fewer than cases in children have been reported in world literature, with surgical management being the only option. an innovative, minimally invasive laparoscopic excision of the abdominal sac was performed and the scrotal component was managed by jaboulay's procedure. this is probably the first case report in world literature describing laparoscopic management of hydrocele-en-bissac. case report: a year old male presented with complaints of bilateral hydrocele and swelling in right lower abdomen since one year. computed tomography of the abdomen revealed an encysted hypodense lesion with enhancing walls along the right side of pelvis, anterior to the psoas muscle and extending through the internal ring into the right inguinal region upto the scrotal sac; measuring . cm . cm suggestive of an encysted hydrocele of cord associated with hydrocele of both scrotal sacs excessive gastric resection may result in postoperative deformity of the stomach, with consequent gastric stasis in food uptake. to minimize the resection of stomach tissue, especially for lesions close to the esophagogastric junction or pyloric ring, we have developed laparoscopic wedge resection (lwr) with the serosal and muscular layers incision technique (samit) for gastric gastrointestinal stromal tumors. this samit is simple and does not require special devices. purpose: the purpose of this study was to clarify whether lwr with samit for gastric gists is technically feasible in term of short-term outcome methods: all patients who went through lsg in our department between / to / have been evaluated for bleeding complications, after implementation of anti-bleeding policy: blood pressure was controlled to mmhg during stomach resection and staple line was reinforced throughout it's length with a running - absorbable v-lock suture. drains were used selectively. results: out of patients who went through the procedure ( . %) suffered hemorrhagic complications: patients had? hb[ gr%. patients received - red blood pc's. no patients were re-operated for bleeding. patients were readmitted for infected hematoma and had ct guided drainage. one patient ( . %) suffered from leak. conclusion: implementation of anti-bleeding policy in lsg is very effective. there is no need to use expensive buttress material to achieve these results. drains can be used selectively. the impact of this policy on leak rate needs to be fifty procedures immediately prior to, immediately after, and eight months after completion of training were included for each endoscopist. data were extracted from the electronic medical record and entered into spss for analysis. student's t-test was used to compare groups for continuous data, and chi-squared tests were used for categorical data. data were collected for procedures. patient groups pre, post, and eight months after csi training were comparable in terms of age ( . yrs, . yrs, and . yrs), sex ( it's in the bag; can stoma output predict acute kidney injury in new ostomates? robert fearn colostomy output stabilised rapidly, whilst ileostomy output increased progressively throughout the first postoperative days as can be seen in chart . twelve patients ( %) developed aki during index admission. length of stay was significantly greater in the aki group at ( % ci - ) days vs ( - ) days. highest daily stoma output was non significantly higher in the aki group ml ( % ci - , ml) vs , ( - , ml) as was mean daily stoma output at ml ( - , ml) vs ml ( - ml) (chart ). seventeen patients ( %) were readmitted for any reason, ( %) specifically for aki. in total patients ( %) developed aki within three months of their stoma surgery only of whom had developed aki during their index admission. all patients who developed aki following their index admission were ileostomy patients. conclusion: acute kidney injury in new stoma patients is associated with prolonged hospital stay and readmissions with associated morbidity and healthcare costs consecutive laparoscopic bariatric operations were performed, including primary roux-en-y gastric bypasses (lrygb), primary adjustable gastric bands (lagb), primary sleeve gastrectomies (lsg) and secondary bariatric surgeries and revisions. all bariatric procedures were approached laparoscopically ( procedures were stapled and were nonstapled). the mean patient age was years ( - ), females represented % and mean bmi was . kg/m ( - ). there were no perioperative mortalities, no conversions to open surgery and no intraoperative blood transfusions. there we two major intraoperative complications (hypopharyngeal perforation- , malignant hyperthermia- ). mean hospital stay was . days ( - days). eleven patients ( . %, in gastric bypass group and one in lsg group) required -day reoperations for postoperative complications (staple line gastrointestinal bleeding- , anastomotic leak- , strangulated port site hernia- , unexplained severe abdominal pain- , intestinal obstruction- , and intraabdominal abscess- ). there were no long term ( -year) mortalities in patients that required reoperation. there was one transfer to another institution. the dynamics of further improving safety was such that there was no complication on the recent consecutive stapled procedures and the mean hospital stay was . days ( - days). detailed subgroup analyses will be provided. conclusions: with well-controlled and structured pre-, intra-, and post-operative care, laparoscopic bariatric surgery can be performed with minimal reoperations and zero mortality in a teaching institution does concomitant placement of a feeding jejunostomy tube during esophagectomy affect quality outcomes? md, facs; icahn school of medicine at mount sinai background: placement of a feeding jejunostomy tube (fj) is often performed during esophagectomy. few studies, however, have sought to determine whether concomitant placement affects postoperative outcomes of esophagectomy of these, ldg was performed patients and odg was performed . we compared elderly patients (aged years or more) with younger patients in each operative procedure. (ldg: elderly , younger ; odg: elderly , younger ) preoperative comorbidity and surgical results were analyzed. multivariate analysis was performed to detect predictive factors for postoperative complications. results: in both ldg and odg groups, the operative time and amount of blood loss did not differ, while comorbidity was more common in elderly patients than in the nonelderly, and there were fewer retrieved lymph nodes in elderly patients. the incidence of all postoperative complications did not differ between both groups in each procedure, and there were no significant differences in the time to first flatus or postoperative hospital stay. however, in terms of specific postoperative complications, respiratory complications were more frequently observed in eldery group with odg significantly (p= . ), while not with ldg group. in multivariable analysis, age was not independent predictor of postoperative complications. conclusion: odg for eldery patients requires attention particularly in postoperative respiratory complications. ldg is a safe and less invasive treatment for gastric cancer in elderly patients who have greater comorbidity. p examining the role of preoperative ineffective esophageal motility in laparoscopic fundoplication outcomes tyler hall there were no significant differences in complications or recurrence rates. preoperative quality of life measures did not vary between the cohorts nor did postoperative scores at three weeks or six months. patients with % ineffective clearance exhibited worse gerd-hrql scores one and two years postoperatively conclusion: preoperative ineffective esophageal motility was shown to result in comparable short-term quality of life following ars. however, gerd-hrql scores at one and two yearsshowed worse outcomes in patients with preoperative iem robotic surgery as part of oncologically adequate ipmn treatment: indications, short and long term results federico gheza eligible patients who had minimally invasive surgery were stratified in multiport laparoscopic and robotic cohorts, and included if they had poi/sbo after surgery. comparative analysis assessed the demographic, perioperative, and postoperative outcomes. the main outcome measures were the incidence rate, associated variables, and time to ileus/ sbo across the mis platforms. results: during the study period total patients were reviewed- laparoscopic and robotic. postoperatively, ( . %) laparoscopic and ( . %) robotic patients suffered from poi/sbo laparoscopic sbo occur significantly later after the index procedure than robotic sbo ( conclusions: the rate of poi/ sbo is considerable and comparable across laparoscopic and robotic approaches. however, there are distinct differences in the severity, time to occurrence, and impact on quality measures, such as los and readmissions between laparoscopic and robotics. this information could be an important factor in which approach the surgeon choses laparoscopic surgical procedure was standard with using laparoscopic linear stapler. responses to surgery were evaluated a month after the operation based upon the american society of hematology evidence-based practice guidelines for itp. results: there was no open conversion in this study. the mean operation time and blood loss were min and g, respectively. there was no case using blood transfusion during and after operation. with regard to complications, one patient ( %) had a postoperative pancreatic fistula that did not require percutaneous drainage. positive responses, including the complete and partial remissions, were achieved in % ( / ). the mean follow-up duration was months, and the -, -, and -year relapse-free survival rates were % for all three time points. conclusions: the present study demonstrated that ls for itp can provide good long-term outcomes two cases of conversion from sp-c to open surgery were excluded. all procedures were followed postoperatively for a minimum of months, and wound complications such as bleeding, fat lysis, infection, or hernia were recorded. patients were classified as having a wound complication or not. results: pure transumbilical sp-c was completed . %, additional trocars were used in . %, and the rate of conversion to open surgery was . %. after a median follow-up of . (range, - ) months few cases performed with hand assist, notes, or single-incision. utilization of robotics was highest for bpd/ds ( of , cases, . %). the greatest number of robotic-assisted cases were sleeve gastrectomy ( , of , , . %) and gastric bypass ( , of , cases, . %). relatively few operations were converted to a different approach (see table). operative time was longer when using robotic approaches for both sleeve ( . vs . minutes, p. ) and bypass ( . vs . , p\ . ). postoperative los was no shorter when using robotic-assistance (see table). unadjusted -day outcomes revealed slightly higher rates of readmission for both operations when using robotic-assistance (see table), and slightly higher rates of complications after robotic sleeve gastrectomy p comparision of perioperative and survival outcomes of laparoscopic versus open gastrectomy after preoperative chemotherapy: a propensity score-matched analysis adjustment for potential selection bias in the surgical approach was made with propensity score-matched (psm) analysis. perioperative and survival outcomes were compared between the lag and og groups. results: in total, patients were identified from the database. after psm analysis, patients who underwent og were one-to-one matched to patients who underwent lag in the setting of nact. these two groups had similar outcomes in terms of intra-and postoperative complications and -year overall survival. however, the lag group had a longer operation time (p= . ) and lower estimated blood loss (p= . ). moreover, compared with patients in the og group, those in the lag group had fewer days until first ambulation conclusion: the present study indicates that lag performed by well-qualified surgeons for treatment of locally advanced gastric cancer after preoperative chemotherapy is as acceptable as og in terms of oncological outcomes. p outcomes of laparoscopic antireflux surgery for gastroesophageal reflux disease: effectiveness and economic benefits kyung won seo, phd; kosin university college of medicine purpose: laparoscopic antireflux surgery (ars) is an alternative treatment option for gastroesophageal reflux disease (gerd) in the world. however, the effectiveness and economic feasibility of ars versus medical treatment is unknown. this study was performed to evaluate the effectiveness and economic benefits of ars. methods: nine patients with gerd were treated using laparoscopic ars between and . surgical results and total cost for surgery were reviewed. results: seven men and women were enrolled. preoperatively, typical symptoms were present in patients, while atypical symptoms were present in patients. one patient underwent partial fundoplication due to absent peristalsis and the other underwent nissen fundoplication. postoperatively, typical symptoms were controlled in of patients, while atypical symptoms were controlled in of patients. overall, at months after surgery, reported partial resolution of gerd symptoms, with achieving complete control. the average cost of ars for nine patients was usd. conclusion: laparoscopic ars is effective for controlling typical and atypical gerd symptoms. the cost of ars may be more economical over the long term compared to medical treatment since laparoscopic surgery is reported to affect respiration and circulation, we should take indication of lag for elderly patients into consideration carefully. indication of lag for elderly patients, however, is still controversial. the aim of this study is to assess the safety and validity of lag for elderly patients. method: medical records were retrospectively reviewed for patients who underwent lag for gastric cancer between and . in this study, patients over years of age were defined as elderly patients. patients were divided into two groups according to age; group a (age ≥ , n= ), group b (age \ , n= ). preoperative characteristics and postoperative outcomes were analyzed. two-tailed student's test and/or pearson's chi-square test were used for statistical analysis. results: there were no significant differences in male/female ratio and body mass index between two groups. number of patients whose asa physical status was ≥ , and/or performance status was ≥ did not differ total gastrectomy ( . vs . %, p= . ), proximal gastrectomy ( vs . %, p= . ). intra-operative blood loss, operating time, and number of harvested lymph nodes did not differ between the two groups. as for postoperative complications such as intra-abdominal abscess ( . vs . %, p= . ), anastomotic leakage ( vs . %, p= . ), significant difference was not observed between the two groups. in addition, respiratory and cardiovascular complication was not observed in elderly patients. incidence of clavien-dindo classification ≥grade ( . vs . %, p= . ), and postoperative hospital stay ( . vs . days, p= . ) did not differ. conclusion: short-term outcomes of lag in elderly patients were not different from those in young patients the essential role of the transcystic duct tube (c-tube) during laparoscopic common bile duct exploration (lcbde) towakai hospital introduction: laparoscopic common bile duct exploration (lcbde) is a standard surgical procedure for the treatment of common bile duct stones (cbds). however, there are some problems associated with cbd drainage after operations even if performing with the primary closure. therefore, we developed a new drainage tube, c-tube, which contributes to shorter drainage periods and reduces perioperative complications. method: c-tube is a type of bile drainage tube which is fixed to the cystic duct with an elastic band. closing the duct with an elastic band as soon as c-tube is removed prevents bile leakage from the stump of the cystic duct. the essential roles of this tube include: . assisting suturing during operations, . use during intra-and post-operative cholangiograpy, . assisting post-operative endoscopic sphincterotomy when necessary we included patients from -years prior to our intervention and compared this with patients who had follow-up after implementation. we excluded patients having revisions, gastric banding, and patients whose primary surgeon had left during the data collection period. we analyzed demographics and follow-up rates at , , , , and months. chi-square test was used to evaluate for significance, and results were corrected for multiple comparison. results: patients met inclusion criteria in the pre-intervention group, and in the postintervention group. of those, were analyzed for the year follow-up visit. the pre-intervention group had males, females, and an average age of . approximately / of the surgeries performed were sg, / were rygb. the post-intervention group had males, females, average age of . approximately half of the post-intervention cases were sg while the rest were rygb. conclusion: bariatric surgery is a useful tool in aiding weight loss and improving comorbidities. it is essential that patients receive long-term follow-up and monitoring to achieve these goals. our program now uses a system of phone call reminders for scheduled visits, as well as calls and letters for annual visits surgeon's evaluation of an intraoperative microbreaks web-app workload questions were modified nasa task load index (physical demand, mental demand, and complexity) and procedural difficulty on - ( =maximum impact) scales. primary outcomes were the impact of microbreaks on surgeons' physical performance, mental focus, pain/discomfort and fatigue with checkboxes for improved, no change and diminished. secondary outcomes were microbreaks impact on distraction level and workflow disruption using a - ( =maximum impact) scale. descriptive statistics were calculated for median and interquartile ranges (iqr) of these responses. results: seven surgeons ( male, female), with a median (iqr) surgical experience of ( . , ) years, completed ten surgical days with a median (iqr) operative duration of ( , ) minutes/surgical day. the median number of microbreaks/surgical day was . the median (iqr) for mental demand, physical demand, surgical complexity and difficulty are shown in table . following each surgical day, surgeons reported / improved physical performance situs inversus totalis (sit) is inherited in an autosomalrecessive fashion with complete abnormal transposition of thoracic & abdominal viscera. its incidence varies from in to live births. for those undergoing surgery, laparoscopic approach is preferred as it avoids inappropriate incisions. however, due to mirroring of the viscera, the surgeon faces constant visio-spatial disorientation during laparoscopy. p ''how to be a surgeon and not dying trying'' control of basic physiological parameters in perioperative phase second main variable: blood pressure (bp) with manual measurement sleeve. preoperative bp and immediate postoperative bp were measured, we were not able to measure intraoperative bp due to the lack of consent of the surgeons involved for the use of other devices different from the heart rate band. secondary variables: years from graduation, years of practice, age, body mass index (bmi), number of medical co-morbidities, number of jobs, sleeping hours the night before. we took measurements to surgeons during a laparoscopic cholecystectomy. results: the mean preoperative heart rate was . bpm. the mean minimum intraoperative heart rate was bpm. the mean maximum intraoperative heart rate was . bpm ( % with tachycardia at the surgery). the mean immediate postoperative heart rate was . cpm. the mean heart rate minutes after the postoperative phase was . cpm. at the immediate preoperative phase % of surgeons had elevated bp level (usual normotensives) articles were randomly selected and the gender of the first and last authors determined. results: of the bariatric surgery publications reviewed, only % of first authors and . % of last authors were female surgeons. even though the proportion of female authors has increased over time, this is not proportional to the increase in the number of female surgeons or surgery residents (figure ). discussion: female surgeons are under-represented in bariatric surgery research. the number of female surgeons and residents has a continuous up trend over the last few decades our survey also included the validated quick-dash (disabilities of the arm, shoulder, and hand) questionnaire for upper-limb symptoms and the ability to perform certain physical activities. the quickdash is scored into two components: disability/symptom score, and the optional work module, which represent the impact of disability on daily activities and work responsibilities, respectively. both scores range from - , with a higher score indicating greater disability. surgeons were grouped according surgical focus (open, lap, or ra), and comparisons were made between groups. surveys with more than % of responses missing were excluded. statistical analysis were done using spss . , with α= . . results: completed surveys were evaluated (open: n= , lap: n= , ra: n= ). the survey response rate was %. . % of respondents were general surgeons, and mean age was ± . years. surgeons reported an average of ± . cases performed per month ra: . %, p= . ). likewise, there were no differences in the mean disability similarly, there was a positive correlation between mean work scores and reported pain in the upper-limb for lap and ra, both p. . conclusions: this nationwide survey revealed a similar prevalence of pain in the upper-limb among surgeons performing open, laparoscopic and robotic-assisted procedures. likewise, similar disability scores were reported between the three surgical groups. older surgeons performing laparoscopic and robotic-assisted approaches reported a higher impact of upper-limb problems interfering with their daily activities, unlike open surgeons. among all surgeons who reported pain in the upper-limb, laparoscopic and robotic surgeons were more likely to report that this pain interferes with their work activities an analysis of subjective and objective fatigue between laparoscopic and robotic surgical skills practice p d laparoscopic versus robotic gastrectomy for gastric cancer: comparisons of short-term surgical outcomes lin chen, xin guo patients who underwent d-lag (n= ) or rag (n= ) for gastric cancer were enrolled. the clinicopathological factors and short-term surgical outcomes were compared with retrospectively analysis. results: the clinicopathological factors between the two groups were well matched. postoperative recovery factors including the days of first flatus, days of eating liquid diet and hospital stay were similar. the rate of postoperative complications between the two groups were with no statistical differences in the subgroups of patients with total gastrectomy, d-lag had less blood loss and shorter operative time than rag (p= . and p. ), while for distal gastrectomy, blood loss and operative time showed no statistical differences. conclusions: this study suggests that d-lag is a novel and acceptable surgical technology in terms of surgical and oncological outcomes. d-lag is a promising approach for gastric cancer therapy methods: patients underwent robotic surgery between the beginning of to first half of in turkey were included. data were obtained from a prospectively maintained database. patient, surgeon and hospital identifiers were encrypted. parameters were operation type, operation year, robotic system used (s, si, xi), hospital volume and surgeon volume. high volume robotic colorectal hospital and surgeon was defined as the caseload within the forth interquartile ( th- th) based on the median value. results: there were colorectal procedures. surgeons performed robotic colorectal surgery at hospitals. ( . %) and ( . %) procedures were performed with the s-si and xi platforms respectively. hospitals have both of the si and xi platforms. hospitals are the si, hospitals are the xi hospital currently. the number of robotic colorectal operations increased gradually by years (figure ). the median numbers of colorectal procedures were (range - ) and (range - ) per hospital and per surgeon respectively among those hvrcs, the numbers of si and xi users were and respectively. the surgeons who performed more than procedures continued to use robot in their practice except one surgeon who stopped at . only left colectomies and no right colonic resection were performed before introduction of the xi platform first robotic cases and implementation of a robotics curriculum in a general surgery residency domenech asbun armonk ny) and utilized student's t test and chi-square. we also performed a linear regression analysis to determine the effect of or time, robotic surgery, and diagnosis on operating room costs and postoperative length of stay. results: laparoscopic and robotic cholecystectomies were performed. demographic parameters (age, gender, medical comorbidities, preoperative albumin and bmi, surgical history and smoking) were comparable. primary diagnosis was significantly different (chi-square . ), driven by more acute cholecystitis in the laparoscopic group. / robotic cases and / ( . %, p = . ) laparoscopic cases were converted to open ( for adhesions, for failure to progress, and for visualization of anatomy after adjusting for or time and diagnosis, robotic surgery was associated with a $ increase in costs robotic surgery is independently associated with increased or cost, but individual hospital systems must decide if this additional cost outweighs increased robot utilization and training benefits for physicians and staff robotic abdominal wall hernia repairs: technical considerations and lessons learned inguinal hernia repairs (ihrs) comprised the majority ( . %) of cases ( . % male, mean age . , mean bmi . ). there were unilateral ihrs with an average operative time of . ± . min and an average ebl of . ml. there were bilateral ihrs with an average operative time of . ± . min and average ebl of . ml. thirteen ihrs were combined with umbilical hernias and two with incisional hernias. average operative time for combined procedures was . min and average ebl was . ml. fifty-five incisional hernias were repaired robotically ( . % male, mean age . , mean bmi . ), four of which were retrorectus and two of those required transversus abdominis release. median hernia size was cm ( - cm). mean operative time was . ± . min and average ebl was . ml. twenty-three ventral/umbilical hernias were repaired robotically ( . % male, mean age . , mean bmi . , median size . cm ( - cm), mean operative time . ± . min, average ebl . ml). one spigelian hernia (operative time min, ebl ml) and one parastomal hernia (operative time min, ebl ml) were repaired robotically. there were no major complications and only groin seroma requiring percutaneous aspiration. nine patients required conclusion: this study demonstrates improved outcomes of robotic inguinal hernia repair compared to an open or laparoscopic approach. robotic hernia repair showed overall lower -day complication and readmission rates, and shortened los. while open approach had the highest rate of opiate use we retrospectively investigated consecutive overweight gc patients (bmi≥ ) underwent distal gastrectomy with d lymphadenectomy ( for rag and for lag) performed by two surgeons. the clinicopathological and surgical features were compared between groups. the cutoff point for initial phase (phase i) and stable phase (phase ii) were determined by cumulative sum (cusum) curve of operation time. results: generally, the surgical outcomes including postoperative complication rate, duration of postoperative hospital stay and lymph nodes harvest in the overweight patients have comparable results between rag and lag groups. the cutoff determining phase i and ii according to the cusum figure for rag group was and cases for surgeon a and b, respectively. and comparison analysis showed that the operation time of phase ii rag was significantly shorter robotic-assisted transabdominal preperitoneal inguinal herniorrhaphy: a single-center experience including perioperative morbidity and short-term outcomes patient factors, treatment factors, and outcome measures were collected in an attempt to gain insight and to generate ideas to potentially improve outcomes. results: there were no operative complications. six patients ( %) had failed gastric pacemaker placement prior to intervention. nine patients ( %) reported improvement in their symptoms and overall quality of life. four patients ( %) reported no improvement in symptoms and required additional intervention for symptom control and supportive care (one underwent roux-en-y gastric bypass, three underwent laparoscopic jejunostomy feeding tube placement to maintain nutrition). conclusion: robotic-assisted pyloroplasty is a safe option that improves symptoms and quality of life in % of our patients patients were matched into cohorts by procedure type. outcomes were analyzed using unpaired t-test and fisher's exact test. results: cost data was available for patients undergoing ras or la procedures. significant increases in equipment, labor, and overhead costs resulted with ras vs. la. variable-labor and variable-overhead costs were significantly higher in la procedures. higher supply costs and longer procedure time was seen with ras in all cohorts however, total -day costs were not significantly different in any group. conclusion: ras led to significant increases in fixed clinical, operative and pathologic factors were reviewed and analyzed. results: seventy patients underwent robotic surgery for rectal cancer during the study period. the locations of tumor were upper rectum, lower rectum. the procedure were as follow, high anterior resection in , low anterior resection in , isr in , apr in patients. eight patients underwent bilateral lymph nodes dissection (llnd). the procedures were performed successfully in all cases. mean age was . years, and % of the patients were men, and the mean body mass index was . (range, . - . ) kg/m . median operative duration was ( - ) minutes. median blood loss was ( - ) ml. median postoperative stay was ( - ) days. mean harvest lymph node number was . ( - ). surgical margins were negative in all cases. there was one conversion due to bleeding during the llnd and anastomotic leakage occurred in two patients. morbidity was %. there was no mortality postoperatively in this series. conclusion: in early series of the selected patients, this technique appears to be fesible and safe when performed by surgeons skilled in laparoscopic colorectal surgery the inactive electrode was placed touching small bowel to simulate accidental thermal injury. the bowel tissue at the site of temperature change was immediately resected and examined histologically for tissue injury. student t-tests were used for all comparisons with a p-value less than . considered statistically significant. results: comparison of the laparoscopic and robotic techniques are displayed in table . energy transfer was quantified using energy leak (per ma), which in these tests averaged . degree celsius change ( % ci . - . ) at the inactive electrode. surface temperature heated to a maximum of . degrees celsius, more in the robotic system than laparoscopy but still clinically negligible. pathology results from in vivo testing showed only thermal injury to the serosa without deeper mural injury. conclusions: stray energy transfer occurs in both laparoscopic and robotic surgery in amounts that are measurable but without clinical relevance. the average change in tissue temperature is less than degrees celsius laparoscopically and less than degrees robotically. while the robotic surgery appears to transfer more stray energy, no significant bowel injuries were caused in either group. p robot assistance can improve the performance of laparoscopic extensive concomitant adhesiolysis: results from a large observational study federico gheza outcomes compared were operative time, conversion rate, overall complications, gastrointestinal (gi) related complications (wound infection, abdominal abscess, anastomotic leak, ileus and small bowel obstruction), hospital length of stay, and -day re-admission rate. two sample t-test was used and p. was considered statistically significant. results: fifty-five robotic colectomies were matched with laparoscopic counterparts based on type of operation: right colectomy (n= ), sigmoidectomy (n= ), low anterior resection (n= ), proctocolectomy (n= ), transverse colectomy (n= ), abdominoperineal resection (n= ), and total abdominal colectomy (n= ) we assessed if technical obstacles of laparoscopic suturing were decreased and if laparoscopic skills overall were improved. surgical outcomes were compared relative to our historic values; we assessed procedure time and operating room efficiency, including set up and turn-over times. results: overall, the d/flexdex system permitted a greater improvement in working speed, superior optical visualization, and better suture handling compared to standard laparoscopy. all surgeries were completed without any complications. historically, we considered laparoscopic suturing to be complicated and inefficient. we relied on tacking devices for mesh fixation, suturing was previously completed with large cumbersome straight laparascopic devices. however, with flexdex and endoeye flex d, tacking devices have been eliminated and suturing technique improved. the mean total procedure times remained comparable for inguinal and hiatal hernia surgeries, and slightly longer for ventral hernias. operating room efficiency, including mean set up and turn-over times also remained unchanged. the acquisition cost for both the olympus endoeye flex d laparoscopic imaging system we performed a cost analysis which showed an average total cost of $ , for laparoscopic sleeve gastrectomy and an average of $ , for robotic assisted. the total reimbursements were $ , for laparoscopic sleeve gastrectomy and $ , for robot assisted. this translated to an average contribution margin of $ , for laparoscopic vs $ , for robot assisted. we analyzed these differences for bypasses as well. laparoscopic bypasses averaged minutes laparoscopically vs robotically. we found an average cost of laparoscopic $ , vs robot assisted $ , , with a contribution margin of $ , laparoscopic vs $ , robot assisted. conclusions: in our study we noted increased operative times with robot assisted operations, especially bypasses which could be explained by increased use of the robotic system for difficult cases such as revisional bypasses. the impact of cost is especially important in this financial climate, and judicious use of resources becomes important when determining surgical approach average or time for rih was minutes compared to lih which was minutes. average intraoperative cost for rih was $ , compared to lih which was $ . of note, one lih was converted to open, whereas none of the rih required conversion. average los was . hours for rih compared to . hours for lih. postoperative pain at one week follow up was the same between both groups. two postoperative surgical site occurrences (sso) occurred in the lih group ( groin seromas), whereas no ssos occurred in the rih group. eleven ventral hernia repairs were examined, were robotic (rvh) and were laparoscopic (lvh). average or time for rvh was minutes compared to minutes for lvh. average intraoperative cost for rvh was $ , compared to lvh which was $ , . no procedure from either group required conversion to open. average los was . hours for rvh, and . hours for lvh. again, postoperative pain was the same at one week follow up for both groups. there were no postoperative complications noted in either cohort. conclusion: operative time and procedural costs for rvh and rih repairs were shown to be longer and more expensive when compared to their laparoscopic counterparts. however, with increased operative experience using the robotic platform, surgical time did show a decreasing trend does robotic system have advantages over laparoscopic system for distal pancreatectomy? results: a total of consecutive patients underwent minimally invasive distal pancreatectomy (ldp n= ; ra-ldp n= ). most common pathologic finding was pancreatic ductal adenocarcinomas ( cases). there was no in-hospital mortality or cases of conversion to open surgery in this study. spleen-preserving approach was performed more often in the ra-ldp ( %) than in the ldp ( . %) groups (p= . ) both groups showed no significant differences in the total number of lymph nodes, number of positive lymph nodes, tumor differentiation, tumor stage, and resection margins. conclusions: ra-ldp is a safe and feasible approach that has an advantage of performing spleenpreserving distal pancreatectomy, with perioperative and short-term oncologic outcomes comparable to those of ldp. p robot-assisted alpps technique mike fruscione right portal vein embolization was not feasible secondary to the proximity and size of the right hemi-liver tumor burden relative to the right portal vein. the pre-operative planned procedure was a right trisectionectomy and microwave ablation of the segment lesion. results: using the da vinci xi surgical system (intuitive surgical, inc.) the right portal vein was dissected, doubly-ligated, and divided. the liver parenchyma was split from the inferior edge to the dome mm medial to the falciform ligament and down to the middle hepatic vein which was preserved to maintain adequate venous outflow. the patient was discharged home on post-operative day two. on post-operative day six, ct volumetrics demonstrated a flr of %. on post-operative day seven, a second stage alpps procedure was performed where the right hepatic artery, middle and right hepatic veins and right hepatic duct were ligated and divided. segments a/b, , , and were removed. the patient was discharged home on post-operative day five they were asked to answer demographic questions and rate their comfort level ( =not comfortable, =very comfortable) with aspects of robotic surgery. paired t-tests and wilcoxon tests were used to assess whether there were changes in comfort level before and after labs, and chi-square goodness of fit tests were used to assess whether dry lab (using inanimate objects), wet lab (using a porcine model), or simulator modules were thought to be most helpful in obtaining specific robotic skills. results: the survey response rate was % (n= ). ninety-one percent of residents felt that robotic surgery is not intuitive. prior to simulation, % of residents felt inadequately prepared to safely operate on the robotic console. following simulation, % felt better prepared and more confident to participate in robotic surgery for the first patients whom we treated (the first-stage group), we invited a visiting expert from a high-volume center to perform the procedure jointly with our hospital's surgeons by using a dual console. for the subsequent patients (the second-stage group), the procedure was performed by our hospital staff alone. in this report, we describe our experience of introduction of robotassisted colectomy and discuss issues for the future. patients and methods: the operative procedure was sigmoid colectomy, low anterior resection, and intersphincteric resection. the median number of lymph nodes dissected was . . the mean operating time was minutes for the first-stage group and minutes for the second-stage group. the median console time was minutes for the first-stage group and minutes for the second-stage group, with no significant differences between the two groups. the mean operating time other than console time was minutes for the first-stage group and minutes for the second-stage group, significantly longer in the latter group. the mean amount of hemorrhage was . g in the first-stage group and g in the second-stage group. no significant differences were found between the two groups in the mean length of postoperative hospital stay. none of the patients in either group developed a complication of clavien-dindo grade iii or higher. conclusions: the use of dual console system was particularly useful for the introduction of robotassisted surgery in our hospital. for the patients whom we treated, we found almost no difference in console time between the first-and second-stage groups. the high-quality instruction received via the dual console was considered to have had a beneficial effect on the operators' learning curve. however, the operations that were set up other than console time, such as roll-in and docking, took significantly longer in the second-stage group when the proctor was not present select specimens from each trial were immediately resected and evaluated for histologic thermal injury. experiments were repeated times based to detect an expected difference of five degrees. student t-tests were used for all comparisons with significance set at . . results: stray energy transfer was higher in the single incision setup compared to the traditional setup (figure ). stray energy in the assistant grasper caused . ± . °c of temperature change in the standard configuration, and . ± . °c in the single incision configuration (p= . ). doubling energy output to w amplified the same finding robotic single-site cholecystectomy of cases: surgical outcomes and comparing with laparoscopic single-site procedure jae hoon lee incisional hernia occurred one case in each group. rssc is safe and feasible procedures. with accumulating of experience, rssc had more short operative time than sslc. comparing to sslc, rssc is relatively suitable to acute gallbladder disease and high bmi and requires a minimal learning curve to transition from traditional multiport to single-port robotic cholecystectomy. p initial experience using da vinci xi robot in colorectal surgery anna r spivak, do, john marks, md; lankenau medical center introduction: the xi robot has been developed to facilitate multiquadrant abdominal surgery. this report presents initial experience to evaluate feasibility and safety of xi robot in colorectal surgery. methods: all cases performed on xi robot were prospectively entered into a robotic database that was queried for colorectal cases performed from intraoperative complications were encountered in cases ( . %), requiring conversion to laparoscopy. none were converted to open. mean length of largest incision . cm. median ebl ml. there was no mortality. there were ( . %) immediate postoperative morbidities: postoperative abscess, bowel perforation, two postoperative bleeds, two hernias, two hematomas, smv thrombosis, small bowel obstruction. perioperative blood transfusions were required in . % of cases. there was one anastomotic leak. median time from surgery to low residue diet and discharge was days. conclusion: initial experience shows robotic colorectal resection with da vinci xi learning curve for robotic sleeve gastrectomy and roux-en-y gastric bypass: achieving equivalence to laparoscopy residents and fellows participated in an analogous fashion in both arms of the study, and patients undergoing re-operative bariatric surgery were excluded. results: a total of patients undergoing rsg (n= ) or rrygb (n= ) were included. for the overall robotic cohort, median age was (range - ), % were american society of anesthesiologists (asa) score , % were asa score , and mean body mass index (bmi) was ± with no differences between procedures. there were no conversions to open. there was one patient with portal vein thrombosis after rsg which occurred in the th rsg and one patient who underwent re-operation in the immediate post-operative period for hemorrhage at the gastro-jejunal anastomosis in the rrygb group; this occurred in the th rrygb. there were no leaks, strictures, or mortalities in either group. mean length of stay was days± for rsg with no difference based on number of procedures performed. in the rrygb group, los decreased after the first five procedures from days± to days±(p= . ). for both procedures, operative time decreased by number of procedures performed (figure). equivalence to lsg in operative time ( minutes± ) was reached after eight robotic procedures were included. the da-vinci xi® was used for the operations. age, gender, body mass index (bmi), asa score, indication for surgery, urgency of procedure, type of procedure, docking number, operation time, estimated blood loss, complications, short (≤ days) and long term ([ days) complications were evaluated. results: patients ( females) were included. median age was . median bmi was , median asa score was . total and completion rrp-ipaa were performed for and patients respectively. the indications were as follows: medical refractory uc (n= ), cancer/dysplasia (n= ), fulminant colitis (n= ), toxic megacolon (n= ), medical treatment resulting in growth retardation (n= ), medical treatment refractory bleeding (n= ). patient with toxic megacolon had an emergent operation. the median docking number was and for completion and total rrp-ipaa respectively. median operative time was minutes. median blood loss was ml. all patients had a stapled ileal j pouch anal anastomosis. all patients had a diverting loop ileostomy at the time of ipaa creation. no intraoperative complications were observed. no conversion to open surgery was needed. the median time to flatus was day. the median time to oral intake was day. patient had a laparotomy on postoperative day due to intra-abdominal bleeding. patient had a bleeding from ileostomy which was treated endoscopically. superficial surgical site infection was observed in patients. patient had a pouchitis managed with oral antibiotics. patient had an ileus responded to conservative treatment. patient had a per-anal bleeding stopped spontaneously. patient had a urinary tract infection responded to antibiotics. patients had pouchitis, patient had a perianal fistula requiring a loop ileostomy and a parastomal hernia was developed in another patient in long term follow up ) were significantly different between the two groups. , pairs undergoing primary and pairs undergoing revisional procedures were successfully matched. robotic gastric bypass was associated with a significantly longer operation length than laparoscopic gastric bypass for both primary (median difference minutes, p. ) and revisional (median difference minutes, p. ) procedures overall, there were no significant differences in anastomotic/staple line leak, -day readmission, reoperation, re-intervention, total event, and mortality rates between matched cohorts. conclusion: when controlling for patient characteristics, those undergoing primary and revisional lrygb and rrygb had no difference in early morbidity. despite the prolonged operative duration, the robotic approach was not associated with any clinical benefit or increased complications for primary or revisional gastric bypass surgery preoperative risk factors were collected. we focused on perioperative outcomes and in hospital complication rate. results: thirty-three patients underwent robot assisted giant hiatal hernia repair at our institution. patients ( %) were years and older and patients ( %) had a bmi higher then. there were no significant differences in patient characteristics between the groups. no patient underwent conversion to open or standard laparoscopy. no mortality was observed and no transfusions were needed. four patients ( %) had a complication, two of them were older than years old. three of the four patient ( %) that had a complication were obese. there were no statistical differences in mortality % and . % of them were with s-si and xi platforms respectively. the median numbers of procedures were (range - ) and (range - ) cases per hospital and per general surgeon respectively. the high volume surgeons (higher than th percentile) performed ( %) of the cases. the xi platform has been the main tool for colorectal surgery only (figure ). conclusions: while xi platform significantly increased caseload in general surgery by facilitating performance of colorectal surgery, its preference in other general surgical fields is not superior to si laparoscopic inguinal hernia repair (tapp) -first experience with the new senhance robotic system robin schmitz ; intuitive surgical inc, loma linda university medical center introduction: crohn's disease is an incurable inflammatory disorder that can affect the entire gastrointestinal tract. while medical management is considered first-line treatment, approximately % of patients with crohn's disease require surgery within years of their initial diagnosis. traditionally, surgery has been performed via an open approach with poor adoption of minimally invasive technique. the aim of this study is to demonstrate the feasibility of robotic-assisted approach as a minimally invasive option for surgical management of crohn's disease and compare the perioperative outcomes with traditional laparotomy. methods: patients who underwent elective resection of the intestine for crohn's disease by roboticassisted or laparotomy approach from to q were identified using icd- codes from premier healthcare database. all the procedures were performed by either general surgeons or colorectal surgeons. since hospital characteristics were comparable between the two cohorts before propensity-score matching, : matching was performed using patient characteristics such as age, gender, race, charlson index score and year of the surgery to create comparable cohorts. sample selection and creation of analytic variables were performed using instant health data (ihd) platform (bhe methods: we conducted a retrospective analysis of , mis inguinal hernia repairs ( , robotic, , laparoscopic) from through with data collected in the premier hospital database. patient, surgeon, and hospital demographics of robotic and laparoscopic inguinal hernia repairs were compared. the adjusted odds ratio of receiving a robotic procedure was calculated for each of the demographic factors using a multivariable logistic regression model. statistical significance was defined as p. . sas software version . was used for statistical analysis. results: the odds of a procedure being robotic increased from inguinal hernia repair is one of the most common general surgery procedures with over , performed annually in the united states. when compared to traditional open inguinal hernia repair (oihr), laparoscopic inguinal hernia repair (lihr) has been associated with faster postoperative recovery rates and lower postoperative pain. with advances in the robotic platform, robotic inguinal hernia repair (rihr) is an available technique that is currently being explored. this study examines lihr and rihr as described in literature to see if one is superior to the other. study design: search terms: ''inguinal hernia repair surgical complications including hematomas ( . %), seromas ( . %), and trocar site infection ( . %) resolved with antibiotics, with a . % postoperative complication rate. conclusion: rihr repair is a safe alternative to lihr, with fewer postoperative complications and a faster recovery time. however, operative time as well as or room time is significantly longer, which may increase overall cost laparoscopic or robotic approach were chosen on a schedule availability basis. data was collected prospectively and it involved anthropometric data, presence of type diabetes mellitus (t dm), % of preoperative total weight loss (%ptwl), surgical time, postoperative length of stay, -day complications, and need for readmission or reoperation. comparison between groups was carried on with t-test for continuous data and with chi-square test for dichotomous variables. a p lower than . was considered significant. results: overall sagb were performed, laparoscopic and robotic. a long and thin gastric pouch was created calibrated by a fr bougie and a . cm antecolic antegastric gastrojejunal (gj) anastomosis was groups (laparoscopic vs robotic) were comparable regarding age ( vs . years, p= . ), bmi ( . vs kg/m , p= . ), %ptwl ( . vs . %, p= . ) and % with t dm ( vs there were fewer men in the laparoscopic group ( . vs % there were ( . %) major complications in the laparoscopic group: bleedings from the gj anastomosis, one of which required reoperation, severe dumping syndrome, gerd requiring revision and gj stricture that underwent relaparoscopy. the only complication ( %) in the robotic group was an acute pancreatitis. readmission rate was % in both groups and reoperation rate was % for laparoscopic and % for robotic surgeries. conclusions: totally robotic sagb with manual gastro jejunal anastomosis was safe and feasible in this early experience compared to laparoscopic approach multi degrees of freedom manipulator with mantle tube for assisting endoscopic and laparoscopic surgical operations masataka nakabayashi, phd , yuta hoshito, masters student p step by step anatomic mapping during laparoscopic transabdominal adrenalectomy lateral flank approach ranbir singh steps analyzed were: right adrenalectomy: step ) mobilize liver; ) medial dissection; ) adrenal vein isolation; ) inferior dissection; ) adrenal off kidney; ) detachment. left adrenalectomy: step ) division splenorenal ligament; ) develop plane pancreas/kidney; ) mobilization medial/lateral borders adrenal; ) adrenal vein isolatoin; ) dissection adrenal off kidney; ) detachment. structures were identified as yes/no and results expressed as percentage total n of cases seen at each step. results: structures identified at each step are shown (table) incisions were made at the oral vestibule under the inferior lip. a -mm trocar was inserted through the center of the oral vestibule with two -mm trocars above incisors. the subplatysmal space was created down to the sternal notch, and carbon dioxide was insufflated at pressure mmhg to maintain the working space. parathyroidectomy was performed using laparoscopic instruments. intraoperative parathromone levels were measured minutes after excision of gland. primary end-points were the success rate in achieving the cure from hyperparathyroid state and hypocalcemia rate. secondary end-points were operating time, scar length, pain intensity assessed by the visual-analogue scale, analgesia request rate, analgesic consumption, quality of life within postoperative days (sf- ), cosmetic satisfaction, duration of postoperative hospitalization, and cost-effectiveness analysis. result: one patient experienced a transient recurrent laryngeal nerve palsy which was spontaneously resolved within month. no permanent recurrent laryngeal nerve injury was found no mental nerve injury or infection was found. conclusion: with highly sensitive localising sestamibi and ct scans, focussed exploration is the current standard of treatment. among all minimally invasive surgeries, toepva is a feasible, safe, and almost pain-free surgical option when combined with intraoperative parathormone monitoring for patients with hyperparathyroidism indocyanine green is a water soluble nontoxic compound exhibiting near infrared renal function and long-term survival. indocyanine fluorescence helps in assessing vascular flow, tissue perfusion and aberrant anatomy and thereby leads to lower conversion rates in partial nephrectomy. we aim to present our experience in patients who underwent partial nephrectomy over years. materials and methods: of the partial nephrectomies performed at our institution, were done by laparoscopic approach alone and rest by patients who underwent llr for whole hepatoma in our facility, underwent llr for a solitary hepatoma and were divided into "before standardization" (bs; n= ) and "after standardization" (as) groups (n= ). patient background, characteristics, and perioperative outcomes were compared between these groups. procedure: we chose the devices according to phases of liver transection. a soft-coagulation monopolar device was used for marking surface. an ultrasonically activated device was used for transection of the liver surface within a -cm depth. crash and sealing with biclamp were indicated for deep-phase transection. the cavitron ultrasonic surgical aspirator was used if the lesion was close to the major glisson's sheath or the major hepatic vein. results: no significant differences in the patients' background were found between the two groups. the operative durations were min ( - min) and min ( - min) in the as and bs groups, respectively, with a significant difference (p. ). the blood loss volumes were cc ( - cc) and cc ( - cc), respectively (p= . ). the lengths of hospital stay after llr were days (range, - days) and days ( - days), respectively, with a significant difference iwao kitazono, phd , kentaro gejima , hizuru kumemura , akira hiwatashi , yuichiro nasu , fumisato sasaki , akio ido , yutaka imoto ; cardiovascular and gastroenterological surgery, kagoshima university graduate school of medical and dental science, digestive and lifestyle disease, kagoshima university graduate school of medical and dental science introduction: in locally-treatable gastrointestinal tumors, laparoscopic endoscopic cooperative surgery (lecs) is a minimally-invasive technique that can avoid excessive resection of the gastrointestinal tract. objective: to share our therapeutic guidelines and surgical technique of lecs for gastroduodenal tumors. subjects: nineteen patients who underwent lecs for gastroduodenal tumors ( patients with gastric tumor and patients with duodenal tumor).[results] ) gastric tumors ( gist, glomus): . site of lesion was u ( patients), m ( ), or l ( ), . operative procedure was acquired in a stepwise manner from classical lecs ( patients) to inverted lecs ( ) to non-exposed endoscopic wall-inversion surgery: news ( ). . operative outcome revealed no postoperative complications. ) duodenal tumors ( adenoma, m cancer, ectopic pancreas): . site of lesion was bulbus duodeni ( patient), superior part ( ), or descending part ( ); . operative procedure was esd followed by laparoscopic continuous suture in a single seromuscular layer for patients with preoperatively confirmed or suspected cancer, or full-thickness resection followed by albert-lembert suture along the short axis for patients unable to undergo esd. in all cases, c-tube was placed to prevent bleeding and perforation at the site of resection due to exposure to bile; . operative outcome included successful endoscopic hemostasis upon bleeding from exposed vessel on postoperative day in patient and anastomotic leak in patient. the event of anastomotic leak resolved after days of bile drainage through c-tube and conservative therapy. compared with patients who underwent esd alone, those who underwent lecs had significantly larger diameters of resected specimens and tumors (p. ) but no significant difference in the incidence of postoperative bleeding and delayed perforation. conclusion: for gastroduodenal tumors, lecs is a minimally-invasive and safe therapeutic option as it combines advantages of both laparoscopy and endoscopy. in particular, c-tube placement for bile drainage was effective in reducing exposure of the suture site to bile as well as supporting drainage after anastomotic leak. introduction: in japan, transurethral balloon catheters (tuc) are currently inserted in most surgical patients to maintain a urine outflow route and to measure the urine output both intraoperatively and postoperatively. however, tuc insertion not only causes postoperative pain but can also lead to urinary tract infections. temporary suprapubic catheters (spc) are used in the field of obstetrics and gynecology as a method of postoperative management to avoid performing transurethral procedures. in the field of surgery, especially in laparoscopic surgery, spc also considered how it would be a useful way to reduce patient suffering. here we report our prospective study on whether an spc can be safely inserted as a substitute for tuc during laparoscopic-assisted colectomy. subjects and methods: the subjects in this study were patients who underwent laparoscopic surgery for primary colorectal cancer from to , and who would normally have had their urinary balloon catheter removed early after surgery. during surgery, an angiomed cystostomy set was installed for patients who gave their consent to participate in this study as an alternative to a urinary balloon catheter. we prospectively collected patient information including sex and age, in addition to other perioperative data, such as, time required for cystostomy, complications accompanying cystostomy, sense of discomfort or pain associated with the vesical fistula after surgery, the time of the removal of the vesical fistula, the frequency of releasing the vesical fistula, postoperative complications. results: our subjects included cases who gave their informed consent to have an spc inserted. an spc was inserted into the remaining case. the mean surgical duration was min, and the spc insertion was performed at a mean of min after the start of surgery. insertion required a mean duration of . s. the bladder of one case ( . %) was perforated, and hematuria was observed at the time of insertion in two cases ( . %), but surgery completed without any incident. six out of cases ( . %) demonstrated neither urinary urgency nor independent urination on the day the catheter was clamped. however, the clamp was released two to four times, and draining of an average of ml urine, urinary urgency, and independent urination were confirmed - days later. conclusion: spc is a procedure that avoids crossing the urethra and its associated disadvantages. here we were able to demonstrate that the procedure can be safely used in laparoscopic surgery patients.our objective is to devise methods for proper port placement to overcome the ergonomic challenges. procedure: patients with sit were operated laparoscopically in our hospital in the period of may to november , males suffering from cholelithiasis without cholecystitis and female with acute appendicitis. after thorough review of literature and proper planning, the patients were posted for surgery. for laparoscopic appendectomy, a thorough initial diagnostic survey is performed on introducing a scope through the umbilical port and confirming the exact location of the appendix. the two working ports are introduced accordingly, which is usually a mirror image of the standard port sites. the appendix was visualised in the left iliac fossa and after meticulous dissection, the appendix and mesoappendix were divided using an endostapler. the operative time was minutes and there were no intraoperative or postoperative complications.the port placement for laparoscopic cholecystectomy in such a case is trickier as the anatomical variation and the contralateral disposition of the biliary tree demand an accurate dissection and exposure of the biliary structures to avoid iatrogenic injuries. it is important to conform to the principles of triangulation during port placement. the mirror image of -port placement is convenient for left-handed surgeons. whereas, to make the procedure comfortable for right-handed surgeons, the working ports need to be shifted caudally with the surgeon standing between the patient's legs. the mean operative time was minutes and there were no minor or major intraoperative or postoperative complications.conclusion: ergonomic comfort is vital to a smooth procedure. while mirroring ports suffices for appendectomy, all other procedures require forethought for port placement. it should be noted that ambidexterity is a desirable skill in the operating room for a laparoscopic surgeon.priscila r armijo, md, chun-kai huang, phd, gurteshwar rana, md, dmitry oleynikov, md, ka-chun siu, phd; university of nebraska medical center introduction: the aim of this study was to determine how objectively-measured and self-reported fatigue of the upper-limb differ between laparoscopic and robotic surgical training environments. methods: surgeons at the sages conference learning center, and at our institution were enrolled. two surgical skills practical environments were utilized: ) a laparoscopic training-box environment (fls) and ) the mimic® dv-trainer (mimic). two standardized surgical tasks were chosen for both environments: peg transfer, and needle passing. each task was performed twice. objective fatigue was evaluated by muscle activation and fatigue, and comparisons were made between fls and mimic, for each surgical task. muscle activation of the upper trapezius, anterior deltoid, flexor carpi radialis, and extensor digitorum were recorded during practice using surface electromyography (emg; trignotm, delsys, inc., boston, ma). the maximal voluntary contraction (mvc) was obtained to normalize muscle effort as %mvc. the median frequency (mdf) was calculated to assess muscle fatigue. subjective fatigue was self-reported by completing the validated -scale score piper fatigue scale- (pfh- ) before and after practice. statistical analysis was done using spss v . , with α= . . results: this abstract represented the performance of trainees (fls: n= , mimic: n= ) as part of larger cohort of the study. for peg transfer, emg analysis revealed that mimic had a significant increase in mean muscle activation for the upper trapezius and anterior deltoid, both p\ . . conversely, practice with fls led to significantly more muscle fatigue than mimic for the same muscle groups (upper trapezius: p= . , anterior deltoid: p= . ), represented by a significantly lower mdf. similarly, for needle passing, mimic had a significant increase in mean muscle activation for the upper trapezius (p= . ) and anterior deltoid (p= . ), but practice with fls significantly induced more muscle fatigue effort for anterior deltoid (p= . ). survey analysis revealed a significant decrease in self-reported fatigue after performing fls tasks (before: . ± . , after: . ± . , p= . ), but no difference after mimic tasks (before: . ± . , after: . ± . , p= . ). conclusions: although different muscle groups are preferentially required in the performance of fls and mimic, our analysis for both surgical tasks showed practice with mimic required more activation of shoulder muscles, whereas practice with fls could lead more muscle fatigue for the same muscle groups. interestingly, surgeons reported improved or no change in perceived fatigue after the tasks, despite of having an increase in muscular activation and effort. subjective selfreport fatigue might not truly reflect the level of fatigue when trainees practice surgical tasks using fls or mimic. objective: to investigate the prevalence of musculoskeletal (msk) injuries in bariatric surgeons around the world. background: as the popularity of bariatric surgery increases, efforts into improving its patient safety and decreasing its invasiveness have also been on the rise. however, with this shift towards minimal invasiveness, surgeon ergonomic constraints have been imposed, with a recent report showing a - % prevalence of physical complaints in surgeons performing laparoscopic surgeries. methods: a web-based survey was designed and sent out to bariatric surgeons around the world. participants were queried about professional background, primary practice setting, and various issues related to bariatric surgeries and msk injuries. results: there were responses returned from surgeons from countries around the world. . % of the surgeons have had more than years of experience in laparoscopic surgery, . % in open and . % in robotic surgery. % of participants reported that they have experienced some level of discomfort/pain attributed to surgical reasons, causing the case load to decrease in . % of the surgeons. it was seen that the back was the most affected area in those performing open surgery, while shoulders and back were equally as affected in those performing laparoscopic, and the neck for those performing robotic, with . % of the surgeons reporting that this pain has affected their task accuracy/surgical performance. a higher percentage of females than males reported pain in the neck, back and shoulder area when performing laparoscopic procedures. supine positioning of patients evoked more discomfort in the wrists, while the french position caused more discomfort in the back region. only . % sought medical treatment for their msk problem, of which . % had to undergo surgery for their issue, and . % of those felt that the treatment resolved their problem. conclusion: msk injuries and pain are a common occurrence among the population of bariatric surgeons, and has the ability to hinder performance at work. therefore, it is of importance to investigate ways in which to improve ergonomics for these surgeons as to improve quality of life.introduction: the use of robotic technology is rapidly increasing among general surgeons but is not being routinely taught in general surgery residency. we aimed to evaluate our first robotic cases during which time we developed a robotic surgery curriculum incorporating residents. methods: the first robotic cases performed at our institution from - by two surgeons were analyzed. a residency curriculum was developed and instituted after the first months. it consisted of online modules offered by intuitive surgical resulting in certification, simulator training, hands on workshops for cannula placement, docking, instrument exchange, camera clutching and other introductory tasks. patient demographics, type of procedure, resident involvement, total operative and console times, comorbid conditions and complications were evaluated. unpaired t tests were performed for statistical analysis. results: females and males comprised this series with an average age of years ± . the majority of patients, % had comorbidities, with a predominance of hypertension, % and diabetes, %. the bariatric patients had an average bmi of ± . a variety of procedures were performed including hernias, foregut and bariatric. residents participated in % of cases. there were no differences in total operative and console times in cases with residents except bariatric procedures. there were complications in this series; postoperative ileus, gallbladder fossa hematoma and an enterotomy. there was one early conversion to open in a complex foregut case and no deaths in this series.conclusions: we report our initial experience of robotics in a variety of general surgery and complex foregut cases. the implementation of a robotic surgery program and residency curriculum was safe with similar outcomes related to operative times and complications. as mis expands with the application of robotics in general surgery, residency curriculums will need to be revised. further data is needed to determine residency learning curves between robotics and laparoscopy.background: robotic surgery has made a large impact in the fields of urology and gynecology. its use is significantly increasing in the fields of general and bariatric surgery. evidence remains unclear as to the clinical impact on outcomes, and significant questions remain as to the impact of cost. our goal was to evaluate the economic impact of robotic surgeries in general and bariatric surgery at our institution. methods: this study is a retrospective analysis of minimally invasive general and bariatric procedures done at a single institution from january through june . we performed a cost and reimbursement analysis of robotic versus conventional laparoscopic surgery. the cost evaluation included operative time, operating room costs, length of stay and overall hospital expenses. in addition, we looked at reimbursement and the contribution margin per cpt code. results: our study included a total of patients who underwent laparoscopic and robot assisted general and bariatric surgeries. the average time duration for laparoscopic surgeries was minutes vs minutes for robot assisted. we performed a cost analysis which showed an average total cost of $ , for laparoscopic and an average of $ , for robot assisted. the total reimbursements were $ , for laparoscopic and $ , for robot assisted. this translated to an average contribution margin of $ , for laparoscopic vs $ , for robot assisted. for general surgery we found an average cost of laparoscopic $ , vs robot assisted $ , , with a contribution margin of $ , laparoscopic vs $ , robot assisted. for bariatric surgeries we found an average contribution margin of $ , for laparoscopic vs $ , for robot assisted. conclusions: robotic surgery has been associated with higher costs and longer operative times. in this economic climate of increased cost awareness with institutions under increasing financial pressures, judicious use of resources becomes important when determining surgical approach. although cost of robot assisted surgery may decrease with time, other quality factors may be important in patient selection. although there is no clear evidence that institutions lose money with robot assisted surgery, in our experience the contribution margin is lower with robot assisted surgery as compared to conventional laparoscopy.introduction: this retrospective study was performed to evaluate the safety and feasibility of the new senhance robotic system (transenterix) for inguinal hernia repairs using the transabdominal preperitoneal approach. our series is the first experience in the field of general surgery utilizing this new robotic platform. methods: from march to september , inguinal hernia repairs in patients were performed using the senhance robotic system. the senhance surgical system is a new robotic platform that consists of a cockpit, manipulator arm and a connection node (figure ). this new system provides robotic surgery with numerous advantages including eye-tracking camera control system, haptic feedback, reusable endoscopic instruments, and a high configuration versatility due to total independency of the manipulator arms. patients were between and years of age, eligible for a laparoscopic procedure with general anesthesia, had no life-threatening disease with a life-expectancy of less than month and a bmi \ . a retrospective chart review was performed for a variety of pre-, peri-and postoperative data including but not limited to patient demographics, hernia characteristics, intraoperative and postoperative complications. results: male and female patients were included in the study. median age was . years (range - years), and median bmi was . (range . - . kg/m ). median docking time was minutes (range - minutes), and median operative time was minutes (range - minutes). two cases were converted to standard laparoscopic surgery due to robot malfunction and intraoperative bleeding respectively. one patient developed a postop seroma that did not require any further intervention. conclusion: we report the first series of laparoscopic inguinal hernia repairs using the new senhance robotic system. compared to previously published conventional laparoscopic or robotic tapp hernia repairs these data suggest similar outcomes in operative time and perioperative complications. additionally there was no significant learning curve detected due to its intuitive applicability. therefor the senhance robotic system can be safely and easily used for tapp hernia repairs by experienced laparoscopic surgeons. this is a video presentation of years old female, who presented with suprapubic pain and mass to gynecology office. she has a history of robotic hysterectomy and sbladder sling operation years ago. this was complicated with peritonitis and long icu stay, due to what she was called ''bowel injury'' but treated only conservatively with antibiotics and subsequent abscess drainages at that time. she has occasional appearing nodule and pain at the left suprapubic region. ct ordered by gynecology read as abdominal wall hernia with long sigmoid diverticuli in hernia. also there was small amount of subcutaneous air at the tip of herniated diverticuli. after antibiotic treatment and improvement, colonoscopy shows, actually the diverticuli is the limb of the sling going through the simoid and anchored in subcutaneous fat on abdominal wall ahich represents clocutaneous fistula as gets infected. clip was placed on sling and repeat imaging comfirmed that the localion of this sling fits to location of so called ''hernia'' the sling limb was resected robotically and colon was repaired with side stapling of clolonic wall. the abdominal wall defect is repaired with long term absorbable suture. as far as we have found, the presentation and treatment of this complication is unique and could not find a similar case to guide us for the plan. background: robot-assisted surgery using da vinci surgical system (dvss) is thought to have many advantages over conventional laparoscopic surgery. it was reported that the use of the surgical robot might reduce surgery-related complications, then a multi-institutional historically controlled prospective cohort study on the feasibility, safety, effectiveness and economical efficiency of robotic gastrectomy (rg) for resectable gastric cancer was conducted in japan. this study evaluated the safety of rg using dvss xi. methods: this single-center, prospective phase ii study included patients with resectable gastric cancer (umin ). the primary endpoint was the incidence of post-operative complications greater than grade iii according to clavien-dindo classification during one month after surgery. the secondary endpoints included all adverse events and completion rate of robotic surgery. results: from oct to jan , patients were enrolled for this study. the incidence of post-operative complication greater than grade iii was %. the overall incidence of adverse events was . % (grade i; . %, grade ii; . %). no patient required conversion to laparoscopic or open surgery; thus, the rg completion rate was %. conclusion: this study suggested the introduction of rg using dvss xi for gastric cancer seems to be safe and feasible. priscila r armijo, md , dmitry oleynikov, md , sages robotic task force* ; university of nebraska medical center, sages robotic task force introduction: while robotic companies continue to aggressively market and promote the use of robots in general surgery, little is known about how this technology is employed by general surgeons, and what is expected of this technology from both novice and experts in the field. the aim of this study is to evaluate the needs of general surgeons who are new to robotic surgery and the needs of established robotic surgeons. methods: the sages robotic task force survey, a one-page survey, was designed and sent electronically to all sages members. questions regarding fellowship training, area of expertise, robotic simulation and in clinical case use, services offered in the current hospital, mentorship, likelihood of switching to a different approach, and expectations for the robot were included in the survey. two groups were created based on previous use of davinci® system in a clinical scenario, or not. statistical analysis was conducted using ibm spss v. . . , using fischer's exact and pearson's chi-squared tests where appropriate. results: sages members answered the survey. surprisingly, respondents ( %) had used the davinci® in a clinical setting. among these, ( %) had additional fellowship training, compared to ( %) in the non-clinical use group, p= . . of all surgeons with additional fellowship training, the great majority ( %) had specialization in advanced gi, mis and bariatric surgery, followed by colorectal ( %). most surgeons are performing less than cases per month using the robotic system, and with the majority of cases performed using the platform being hernia repairs ( %), followed by foregut-related procedures ( %). interestingly, from all the surgeons who replied the survey, only . % are planning to switch from open procedures to its robot counterpart, whereas . % are planning to adopt robotic-assisted procedures rather than laparoscopy. conclusions: the majority of sages members who responded to the survey have used the davinci® in a clinical setting in the past. surgeons who stated they perform mainly laparoscopic procedures were likely to continue to adopt robotic techniques, whereas those who perform open hernia repair for example were not very likely to switch to robotic approach. while the use of the robot may be enabling surgeons who used to perform mostly open procedures in the urology or gynecology fields, laparoscopic skills predict robotic utilization in general surgery. hernia and foregut appear to be the most common procedures that are being utilized.aim: while conventional multiport laparoscopic splenectomy has become gold standard for some hematological or splenic diseases, reduced-port laparoscopic splenectomy (rpls) including singleincision laparoscopic splenectomy (sils) is regarded as highly challenging. herein, we describe the technical refinements for safe rpls especially for patient with splenomegaly. methods: in all cases, access was achieved via a . -cm mini-laparotomy at the umbilicus into which a sils tm port or e-z access ® with three -mm trocars was placed. a -mm flexible scope, an articulating grasper, and straight instruments were used. our rpls is characterized by the followings: a) early ligation of the splenic artery to shrink the spleen, b) application of our original "tug exposure technique," which provides good exposure of the splenic hilum by retracting (tugging) the spleen with a cloth tape, and c) safe introduction of stapler under the guidance with a flat drain into the splenic hilum. results: rpls patients ( men and women, ± years old) comprised hematological disorder (n= ), splenic disease (n= ), and liver cirrhosis (n= ). in patients ( %), rpls was successfully completed: sils in and sils plus one additional port only in patients. conversion to open surgery was necessary in patients including liver cirrhosis with remarkable collateral varicose veins around the spleen. operation time and blood loss were ± min and ± g, respectively. weight of the extracted spleen was heavier than normal and ± g (maximum g). no intra-or postoperative complication occurred. the postoperative scar was nearly invisible. conclusions: rpls might safely be performed even for splenomegaly (up to , g). however, care should be taken for cirrhotic patient with collateral veins. rpls can be the procedure of choice even in the patients with splenomegaly and who are concerned about postoperative cosmesis. the aim of this feasibility study was to evaluate laparoscopic sn biopsy for laparoscopic snns in early gastric cancer patients. subjects and methods: this study includes patients with ct n m (primary tumor \ cm) gastric cancer who underwent laparoscopic sn biopsy in conjunction with radioisotope and dye methods between jan. and jul. . first, we looked for green-dyed sns after injection of indocyanine green (icg) without near-infrared light system, and then tried to detect the radioactivity of sns using a hand-held gamma probe inserted through a small incision at the umbilical port. after the areas where sns were distributed were resected, a gastrectomy with prophylactic lymphadenectomy was performed according to the gastric cancer treatment guidelines of the japanese gastric cancer association. we looked for undetected sns in the resected specimen at the back table. results: among cases, there were ( %) in which sns were not detected in the resected specimen. there were cases in whom sns were detected in the resected specimen. in both cases, the primary tumors were located in the middle and greater curvature of the stomach. in case , laparoscopic sn biopsy identified the left ( sb) and right ( d) greater-curvature lymph node (lns) as sns, however, lesser-curvature ( ) and infrapyloric ( ) lns remained as sns in the resected specimen. in case , the left ( sb) and right ( d) greater-curvature lns were identified as sns intraoperatively, while the lesser-curvature ( ) ln remained as an sn in the resected specimen. the sns overlooked with laparoscopic sn biopsy method were detected by radioisotope only. no cases had ln metastasis, and the -year relapse-free survival rate of these patients was %. conclusions: our feasibility study of laparoscopic sentinel node biopsy for early gastric cancer showed that we should search for sns of the lesser curvature carefully even if the primary lesion is located at the greater curvature. key: cord- -fr uod authors: nan title: saem abstracts, plenary session date: - - journal: acad emerg med doi: . /j. - . . .x sha: doc_id: cord_uid: fr uod nan objectives: we sought to determine if the ocp policy resulted in a meaningful and sustained improvement in ed throughput and output metrics. methods: a prospective pre-post experimental study was conducted using administrative data from community and tertiary centers across the province. the study phases consisted of the months from february to september compared against the same months in . operational data for all centres were collected through the edis tracking systems used in the province. the ocp included main triggers: ed bed occupancy > %, at least % of ed stretchers blocked by patients awaiting inpatient bed or disposition decision, and no stretcher available for high acuity patients. when all criteria were met, selected boarded patients were moved to an inpatient unit (non-traditional care space if no bed available). the primary outcome was ed length of stay (los) for admitted patients. the ed load of boarded patients from - am was reported the editors of academic emergency medicine (aem) are honored to present these abstracts accepted for presentation at the annual meeting of the society for academic emergency medicine (saem), may to in chicago, illinois. these abstracts represent countless hours of labor, exciting intellectual discovery, and unending dedication by our specialty's academicians. we are grateful for their consistent enthusiasm, and are privileged to publish these brief summaries of their research. this year, saem received abstracts for consideration, and accepted . each abstract was independently reviewed by up to six dedicated topic experts blinded to the identity of the authors. final determinations for scientific presentation were made by the saem program scientific subcommittee co-chaired by ali s. raja, md, mba, mph and steven b. bird, md, and the saem program committee, chaired by michael l. hochberg, md. their decisions were based on the final review scores and the time and space available at the annual meeting for oral and poster presentations. there were also innovation in emergency medicine education (ieme) abstracts submitted, of which were accepted. the ieme subcommittee was co-chaired by joanna leuck, md and laurie thibodeau, md. we present these abstracts as they were received, with minimal proofreading and copy editing. any questions related to the content of the abstracts should be directed to the authors. presentation numbers precede the abstract titles; these match the listings for the various oral and poster sessions at the annual meeting in chicago, as well as the abstract numbers (not page numbers) shown in the key word and author indexes at the end of this supplement. all authors attested to institutional review board or animal care and use committee approval at the time of abstract submission, when relevant. abstracts marked as ''late-breakers'' are prospective research projects that were still in the process of data collection at the time of the december abstract deadline, but were deemed by the scientific subcommittee to be of exceptional interest. these projects will be completed by the time of the annual meeting; data shown here may be preliminary or interim. on behalf of the editors of aem, the membership of saem, and the leadership of our specialty, we sincerely thank our research colleagues for these contributions, and their continuing efforts to expand our knowledge base and allow us to better treat our patients. david background: two to ten percent of patients evaluated in the emergency departments (ed) present with altered mental status (ams). the prevalence of non-convulsive seizure (ncs) and other electroencephalographic (eeg) abnormalities in this population is not known. this information is needed to make recommendations regarding the routine use of emergent eeg in ams patients. objectives: to identify the prevalence of ncs and other eeg abnormalities in ed patients with ams. methods: an ongoing prospective study at two academic urban ed. inclusion: patients ‡ years old with ams. exclusion: an easily correctable cause of ams (e.g. hypoglycemia, opioid overdose). a -minute eeg with the standard electrodes was performed on each subject as soon as possible after presentation (usually within hour). outcome: the rate of eeg abnormalities based on blinded review of all eegs by two boardcertified epileptologists. descriptive statistics are used to report eeg findings. frequencies are reported as percentages with % confidence intervals (ci), and inter-rater variability is reported with kappa. results: the interim analysis was performed on consecutive patients (target sample size: ) enrolled from may to october (median age: , range - , % male). eegs for patients were reported uninterpretable by at least one rater ( by both raters). of the remaining , only ( %, %ci - %) were normal according to either rater (n = by both). the most common abnormality was background slowing (n = , %, %ci - %) by either rater (n = by both), indicating underlying encephalopathy. ncs was diagnosed in patients ( %, %ci, - %) by at least one rater (n = by both), including ( %, %ci - %) patients in non-convulsive status epilepticus (ncse). patients ( %, %ci - %) had interictal epileptiform discharges read by at least one rater (n = by both) indicating cortical irritability and an increased risk of spontaneous seizure. inter-rater reliability for eeg interpretations was modest (kappa: . , %ci . - . ). objectives: to define diagnostic sbi and non-bacterial (non-sbi) biosignatures using rna microarrays in febrile infants presenting to emergency departments (eds). methods: we prospectively collected blood for rna microarray analysis in addition to routine screening tests including white blood cell (wbc) counts, urinalyses, cultures of blood, urine, and cerebrospinal fluid, and viral studies in febrile infants days of age in eds . we defined sbi as bacteremia, urinary tract infection (uti), or bacterial meningitis. we used class comparisons (mann-whitney p < . , benjamini for mtc and . fold change filter), modular gene analysis, and k-nn algorithms to define and validate sbi and non-sbi biosignatures in a subset of samples. results: % ( / ) of febrile infants were evaluated for sbi. . % ( / ) had sbi ( ( . %) bac-teremia, ( . %) utis, and ( . %) bacterial meningitis). infants with sbis had higher mean temperatures, and higher wbc, neutrophil, and band counts. we analyzed rna biosignatures on febrile infants: sbis ( meningitis, bacteremia, uti), non-sbis ( influenza, enterovirus, undefined viral infections), and healthy controls. class comparisons identified , differentially expressed genes between sbis and non-sbis. modular analysis revealed overexpression of interferon related genes in non-sbis and inflammation related genes in sbis. genes were differently expressed (p < . ) in each of the three non-sbi groups vs sbi group. unsupervised cluster analysis of these genes correctly clustered % ( / ) of non-sbis and sbis. k-nn algorithm identified discriminatory genes in training set ( non-sbis vs sbis) which classified an independent test ( non-sbis vs sbis) with % accuracy. four misclassified sbis had over-expression of interferon-related genes, suggesting viral-bacterial co-infections, which was confirmed in one patient. background: improving maternal, newborn, and child health (mnch) is a leading priority worldwide. however, limited frontline health care capacity is a major barrier to improving mnch in developing countries. objectives: we sought to develop, implement, and evaluate an evidence-based maternal, newborn, and child survival (mncs) package for frontline health workers (fhws). we hypothesized that fhws could be trained and equipped to manage and refer the leading mnch emergencies. methods: setting -south sudan, which suffers from some of the world's worst mnch indices. assessment/intervention -a multi-modal needs assessment was conducted to develop a best-evidence package comprised of targeted trainings, pictorial checklists, and reusable equipment and commodities ( figure ). program implementation utilized a trainingof-trainers model. evalution - ) pre/post knowledge assessments, ) pre/post objective structured clinical examinations (osces), ) focus group discussions, and ) closed-response questionnaires. results: between nov to oct , local trainers and fhws were trained in of the states in south sudan. knowledge assessments among trainers (n = ) improved significantly from . % (sd . ) to . % (sd . ) (p < . ). mean scores a maternal osce and a newborn osce pre-training, immediately post-training, and upon - month follow-up are shown in the table. closed-response questionnaires with fhws revealed high levels of satisfaction, use, and confidence with mncs materials. participants reported an average of . referrals (range - ) to a higher level of care in the - months since training. furthermore, . % of fhws were more likely to refer patients as a result of the training program. during seven focus group discussions with trained fhws, respondents (n = ) reported high satisfaction with mncs trainings, commodities, and checklists, with few barriers to implementation or use. conclusion: these findings suggest mncs has led to improvements in south sudanese fhws' knowledge, skills, and referral practices with respect to appropriate management of mnch emergencies. no study has compared various lactate measurements to determine the optimal parameter to target. objectives: to compare the association of blood lactate kinetics with survival in patients with septic shock undergoing early quantitative resuscitation. methods: preplanned analysis of a multicenter edbased rct of early sepsis resuscitation targeting three physiological variables: cvp, map, and either central venous oxygen saturation or lactate clearance. inclusion criteria: suspected infection, two or more sirs criteria, and either sbp < mmhg after a fluid bolus or lactate > mmol/l. all patients had an initial lactate measured with repeat at two hours. normalization of lactate was defined a lactate decline to < . mmol/l in a patient with an intial lactate ‡ . . absolute lactate clearance (initial -delayed value), and relative ((absolute clearance)/(initial value)* ) were calculated if the initial lactate was ‡ . . the outcome was in-hospital survival. receiver operating characteristic curves were constructed and areas under the curve (auc) were calculated. difference in proportions of survival between the two groups at different lactate cutoffs were analyzed using % ci and fisher exact tests. results: of included patients, the median initial lactate was . mmol/l (iqr . , . ), and the median absolute and relative lactate clearance were mmol/l (iqr . , . ) and % (iqr , ). an initial lactate > . mmol/l was seen in / ( %), and / ( %) patients normalized their lactate. overall sutures on trunk and extremity lacerations that present in the ed. the use of absorbable sutures in the ed setting confers several advantages: patients do not need to return for suture removal which results in a reduction in ed crowding, ed wait times, missed work or school days, and stressful procedures (suture removal) for children. objectives: the primary objective of this study is to compare the cosmetic outcome of trunk and extremity lacerations repaired using absorbable versus nonabsorbable sutures in children and adults. a secondary objective is to compare complication rates between the two groups. methods: eligible patients with lacerations were randomly allocated to have their wounds repaired with vicryl rapide (absorbable) or prolene (nonabsorbable) sutures. at a day follow-up visit the wounds were evaluated for infection and dehiscence. after months, patients were asked to return to have a photograph of the wound taken. two blinded plastic surgeons using a previously validated mm visual analogue scale (vas) rated the cosmetic outcome of each wound. a vas score of mm or greater was considered to be a clinically significant difference. results: of the patients enrolled, have currently completed the study including in the vicryl rapide group and in the prolene group. there were no significant differences in the age, race, sex, length of wound, number of sutures, or layers of repair in the two groups. the observer's mean vas for the vicryl rapide group was . mm ) and that for the prolene group was . mm ( %ci . - . ), resulting in a mean difference of . mm ( %ci- . to . , p = . ). there were no significant differences in the rates of infection, dehiscence, or keloid formation between the two groups. conclusion: the use of vicryl rapide instead of nonabsorbable sutures for the repair of lacerations on the trunk and extremities should be considered by emergency physicians as it is an alternative that provides a similar cosmetic outcome. objectives: to determine the relationship between infection and time from injury to closure, and the characteristics of lacerations closed before and after hours of injury. methods: over an month period, a prospective multi-center cohort study was conducted at a teaching hospital, trauma center and community hospital. emergency physicians completed a structured data form when treating patients with lacerations. patients were followed to determine whether they had suffered a wound infection requiring treatment and to determine a cosmetic outcome rating. we compared infection rates and clinical characteristics of lacerations with chisquare and t-tests as appropriate. results: there were patients with lacerations; had documented times from injury to closure. the mean times from injury to repair for infected and noninfected wounds were . vs. . hrs (p = . ) with % of lacerations treated within hours and % ( ) treated hours after injury. there were no differences in the infection rates for lacerations closed before ( . %, %ci . - . ) or after ( . %, %ci . - . ) hours and before ( . %, % ci . %- . %) or after ( . %, % ci . %- . %) hours. the patients treated hours after injury tended to be older ( vs. yrs p = . ) and fewer were treated with primary closure ( % vs. % p < . ). comparing wounds or more hours after injury with more recent wounds, there was no effect of location on decision to close. wounds closed after hours did not differ from wounds closed before hours with respect to use of prophylactic antibiotics, type of repair, length of laceration, or cosmetic outcome. conclusion: closing older lacerations, even those greater than hours after injury, does not appear to be associated with any increased risk of infection or adverse outcomes. excellent irrigation and decontamination over the last years may have led to this change in outcome. background: deep burns may result in significant scarring leading to aesthetic disfigurement and functional disability. tgf-b is a growth factor that plays a significant role in wound healing and scar formation. objectives: the current study was designed to test the hypothesis that a novel tgf-b antagonist would reduce scar contracture compared with its vehicle in a porcine partial thickness burn model. methods: ninety-six mid-dermal contact burns were created on the backs and flanks of four anesthetized young swine using a gm aluminum bar preheated to °celsius for seconds. the burns were randomized to treatment with topical tgf-b antagonist at one of three concentrations ( , , and ll) in replicates of in each pig. dressing changes and reapplication of the topical therapy were performed every days for weeks then twice weekly for an additional weeks. burns were photographed and full thickness biopsies were obtained at , , , , and days to determine reepithelialization and scar formation grossly and microscopically. a sample of burns in each group had % power to detect a % difference in percentage scar contracture. results: a total of burns were created in each of the three study groups. burns treated with the high dose tgf-b antagonist healed with less scar contracture than those treated with the low dose and control ( ± %, ± %, and ± %; anova p = . ). additionally, burns treated with the higher, but not the lower dose of tgf-b antagonist healed with significantly fewer full thickness scars than controls ( . % vs. % vs. . % respectively; p < . ). there were no infections and no differences in the percentage wound reepithelialization among all study groups at any of the time points. conclusion: treatment of mid-dermal porcine contact burns with the higher dose tgf-b antagonist reduced scar contracture and rate of deep scars compared with the low dose and controls. background: diabetic ketoacidosis (dka) is a common and lethal complication of diabetes. the american diabetes association recommends treating adult patients with a bolus dose of regular insulin followed by a continuous insulin infusion. the ada also suggests a glucose correction rate of - mg/dl/hr to minimize complications. objectives: compare the effect of bolus dose insulin therapy with insulin infusion to insulin infusion alone on serum glucose, bicarbonate, and ph in the initial treatment of dka. methods: consecutive dka patients were screened in the ed between march ' and june ' . inclusion criteria were: age > years, glucose > mg/dl, serum bicarbonate or ketonemia or ketonuria. exclusion criteria were: congestive heart failure, current hemodialysis, pregnancy, or inability to consent. no patient was enrolled more than once. patients were randomized to receive either regular insulin . units/kg or the same volume of normal saline. patients, medical and research staff were blinded. baseline glucose, electrolytes, and venous blood gases were collected on arrival. bolus insulin or placebo was then administered and all enrolled patients received regular insulin at rate of . unit/kg/hr, as well as fluid and potassium repletion per the research protocol. glucose, electrolytes, and venous blood gases were drawn hourly for hours. data between two groups were compared using unpaired t-test. results: patients were enrolled, with being excluded. patients received bolus insulin; received placebo. no significant differences were noted in initial glucose, ph, bicarbonate, age, or weight between the two groups. after the first hour, glucose levels in the insulin group decreased by mg/dl compared to mg/dl in the placebo group (p = . , % ci . to . ). changes in mean glucose levels, ph, bicarbonate level, and ag were not statistically different between the two groups for the remainder of the hour study period. there was no difference in the incidence of hypoglycemia in the two groups. conclusion: administering a bolus dose of regular insulin decreased mean glucose levels more than placebo, although only for the first hour. there was no difference in the change in ph, serum bicarbonate or anion gap at any interval. this suggests that bolus dose insulin may not add significant benefit in the emergency management of dka. ihca; . return of spontaneous circulation (rsoc). traumatic cardiac arrests were excluded. we recorded baseline demographics, arrest event characteristics, follow-up vitals and laboratory data, and in-hospital mortality. apache ii scores were calculated at the time of rosc, and at hrs, hrs, and hrs. we used simple descriptive statistics to describe the study population. univariate logistic regression was used to predict mortality with apache ii as a continuous predictor variable. discrimination of apache ii scores was assessed using the area under the curve (auc) of the receiver operator characteristic (roc) curve. results: a total of patients were analyzed. the median age was years (iqr: - ) and % were female. apache ii score was a significant predictor of mortality for both ohca and ihca at baseline and at all follow-up time points (all p < . ). discrimination of the score increased over time and achieved very good discrimination after hrs (table, figure) . conclusion: the ability of apache ii score to predict mortality improves over time in the hours following cardiac arrest. these data suggest that after hours, apache ii scoring is a useful severity of illness score in all post-cardiac arrest patients. background: admission hyperglycemia has been described as a mortality risk factor for septic non-diabetics, but the known association of hyperglycemia with hyperlactatemia (a validated mortality risk factor in sepsis) has not previously been accounted for. objectives: to determine whether the association of hyperglycemia with mortality remains significant when adjusted for concurrent hyperlactatemia. methods: this was a post-hoc, nested analysis of a single-center cohort study. providers identified study subjects during their ed encounters; all data were collected from the electronic medical record. patients: nondiabetic adult ed patients with a provider-suspected infection, two or more systemic inflammatory response syndrome criteria, and concurrent lactate and glucose testing in the ed. setting: the ed of an urban teaching hospital; to . analysis: to evaluate the association of hyperglycemia (glucose > mg/dl) with hyperlactatemia (lactate ‡ . mmol/l), a logistic regression model was created; outcome-hyperlactatemia; primary variable of interest-hyperglycemia. a second model was created to determine if concurrent hyperlactatemia affects hyperglycemia's association with mortality; outcome- -day mortality; primary risk variablehyperglycemia with an interaction term for concurrent hyperlactatemia. both models were adjusted for demographics, comorbidities, presenting infectious syndrome, and objective evidence of renal, respiratory, hematologic, or cardiovascular dysfunction. results: ed patients were included; mean age ± years. ( %) subjects were hyperglycemic, ( %) hyperlactatemic, and ( %) died within days of the initial ed visit. after adjustment, hyperglycemia was significantly associated with simultaneous hyperlactatemia (or . , %ci . , . ). hyperglycemia with concurrent hyperlactatemia was associated with increased mortality risk (or . , %ci . , . ) , but hyperglycemia in the absence of simultaneous hyperlactatemia was not (or . , %ci . , . ) . conclusion: in this cohort of septic adult non-diabetic patients, mortality risk did not increase with hyperglycemia unless associated with simultaneous hyperlactatemia. the previously reported association of hyperglycemia with mortality in this population may be due to the association of hyperglycemia with hyperlactatemia. the background: near infrared spectroscopy (sto ) represents a measure of perfusion that provides the treating physician with an assessment of a patient's shock state and response to therapy. it has been shown to correlate with lactate and acid/base status. it is not known if using information from this monitor to guide resuscitation will result in improved patient outcomes. objectives: to compare the resuscitation of patients in shock when the sto monitor is or is not being used to guide resuscitation. methods: this was a prospective study of patients undergoing resuscitation in the ed for shock from any cause. during alternating day periods, physicians were blinded to the data from the monitor followed by days in which physicians were able to see the information from the sto monitor and were instructed to resuscitate patients to a target sto value of . adult patients (age> ) with a shock index (si) of > . (si = heart rate/systolic blood pressure) or a blood pressure < mmhg systolic who underwent resuscitation were enrolled. patients had a sto monitor placed on the thenar eminence of their least-injured hand. data from the sto monitor were recorded continuously and noted every minute along with blood pressure, heart rate, and oxygen saturation. all treatments were recorded. patients' charts were reviewed to determine the diagnosis, icu-free days in the days after enrollment, inpatient los, and -day mortality. data were compared using wilcoxon rank sum and chi-square tests. results: patients were enrolled, during blinded periods and during unblinded periods. the median presenting shock index was . (range . to . ) for the blinded group and . ( . - . ) for the unblinded group (p = . ). the median time in department was minutes (range - ) for the blinded and minutes (range - ) for the unblinded groups (p = . ). the median hospital los was day (range - ) for the blinded group, and days (range - ) in the unblinded group (p = . ). the mean icu-free days was ± for the blinded group and ± for the unblinded group (p = . ). among patients where the physician indicated using the sto monitor data to guide patient care, the icu-free days were . ± for the blinded group and . ± for the blinded group (p = . ). background: inducing therapeutic hypothermia (th) using °c iv fluids in resuscitated cardiac arrest patients has been shown to be feasible and effective. limited research exists assessing the efficiency of this cooling method. objectives: the objective was to determine an efficient infusion method for keeping fluid close to °c upon exiting an iv. it was hypothesized that colder temperatures would be associated with both higher flow rate and insulation of the fluid bag. methods: efficiency was studied by assessing change in fluid temperature ( c) during the infusion, under three laboratory conditions. each condition was performed four times using liter bags of normal saline. fluid was infused into a ml beaker through gtts tubing. flow rate was controlled using a tubing clamp and in-line transducer with a flowmeter, while temperature was continuously monitored in a side port at the terminal end of the iv tubing using a digital thermometer. the three conditions included infusing chilled fluid at a rate of ml/min, which is equivalent to ml/kg/hr for an kg patient, ml/min, and ml/min using a chilled and insulated pressure bag. descriptive statistics and analysis of variance was performed to assess changes in fluid temperature. results: the average fluid temperatures at time were . ( % ci . - . ) ( ml/min), . ( % ci . - . ) ( ml/min), and . ( % ci . - . ) ( ml/min + insulation). there was no significant difference in starting temperature between groups (p = . ). the average fluid temperatures after ml had been infused were . ( % ci . - . ) ( ml/min), . ( % ci . - . ) ( ml/min), and . ( % ci . - . ) ( ml/min + insulation). the higher flow rate groups had significantly lower temperature than the lower flow rate after ml of fluid had been infused (p < . ). the average fluid temperatures after ml had been infused were . ( % ci . - . ) ( ml/min), . ( % ci . - . ) ( ml/min), and . ( % ci . - . ) ( ml/min + insulation). there was a significant difference in temperature between all three groups after ml of fluid had been infused (p < . ). conclusion: in a laboratory setting, the most efficient method of infusing cold fluid appears to be a method that both keeps the bag of fluid insulated and is infused at a faster rate. fluid bolus. patients were categorized by presence of vasoplegic or tissue dysoxic shock. demographics and sequential organ failure assessment (sofa) scores were evaluated between the groups. the primary outcome was in-hospital mortality. data were analyzed using t-tests, chi-squared test, and proportion differences with % confidence intervals as appropriate. results: a total of patients were included: patients with vasoplegic shock and with tissue dysoxic shock. there were no significant differences in age ( vs. years), caucasian race ( % vs. %), or male sex ( % vs. %) between the dysoxic shock and vasoplegic shock groups, respectively. the group with vasoplegic shock had a lower initial sofa score than did the group with tissue dysoxic shock ( . vs. . points, p = . ). the primary outcome of in-hospital mortality occurred in / ( %) of patients with vasoplegic shock compared to / ( %) in the group with tissue dysoxic shock (proportion difference %, % ci - %, p < . ). conclusion: in this analysis of patients with septic shock, we found a significant difference in in-hospital mortality between patients with vasoplegic versus tissue dysoxic septic shock. these findings suggest a need to consider these differences when designing future studies of septic shock therapies. background: the pre-shock population, ed sepsis patients with tissue hypoperfusion (lactate of . - . mm), commonly deteriorates after admission and requires transfer to critical care. objectives: to determine the physiologic parameters and disease severity indices in the ed pre-shock sepsis population that predict clinical deterioration. we hypothesized that neither initial physiologic parameters nor organ function scores will be predictive. methods: design: retrospective analysis of a prospectively maintained registry of sepsis patients with lactate measurements. setting: an urban, academic medical center. participants: the pre-shock population, defined as adult ed sepsis patients with either elevated lactate ( . - . mm) or transient hypotension (any sbp < mmhg) receiving iv antibiotics and admitted to a medical floor. consecutive patients meeting pre-shock criteria were enrolled over a -year period. patients with overt shock in the ed, pregnancy, or acute trauma were excluded. outcome: primary patientcentered outcome of increased organ failure (sequential organ failure assessment [sofa] score increase > point, mechanical ventilation, or vasopressor utilization) within hours of admission or in-hospital mortality. results: we identified pre-shock patients from screened. the primary outcome was met in % of the cohort and % were transferred to the icu from a medical floor. patients meeting the outcome of increased organ failure had a greater shock index ( . vs . , p = . ) and heart rate ( vs , p < . ) with no difference in initial lactate, age, map, or exposure to hypotension (sbp < mmhg). there was no difference in the predisposition, infection, response, and organ dysfunction (piro) score between groups ( . vs . , p = . ). outcome patients had similar initial levels of organ dysfunction but had higher sofa scores at , , and hours, a higher icu transfer rate ( vs %, p < . ), and increased icu and hospital lengths of stay. conclusion: the pre-shock sepsis population has a high incidence of clinical deterioration, progressive organ failure, and icu transfer. physiologic data in the ed were unable to differentiate the pre-shock sepsis patients who developed increased organ failure. this study supports the need for an objective organ failure assessment in the emergency department to supplement clinical decision-making. background: lipopolysaccharide (lps) has long been recognized to initiate the host inflammatory response to infection with gram negative bacteria (gnb). large clinical trials of potentially very expensive therapies continue to have the objective of reducing circulating lps. previous studies have found varying prevalence of lps in blood of patients with severe sepsis. compared with sepsis trials conducted years ago, the frequency of gnb in culture specimens from emergency department (ed) patients enrolled in clinical trials of severe sepsis has decreased. objectives: test the hypothesis that prior to antibiotic administration, circulating lps can be detected in the plasma of fewer than % of ed patients with severe sepsis. methods: secondary analysis of a prospective edbased rct of early quantitative resuscitation for severe sepsis. blood specimens were drawn at the time severe sepsis was recognized, defined as two or more systemic inflammatory criteria and a serum lactate > mm or spb< mmhg after fluid challenge. blood was drawn in edta prior to antibiotic administration or within the first several hours, immediately centrifuged, and plasma frozen at ) °c. plasma lps was quantified using the limulus amebocyte lysate assay (lal) by a technician blinded to all clinical data. results: patients were enrolled with plasma samples available for testing. median age was ± years, % female, with overall mortality of %. forty of patients ( %) had any culture specimen positive for gnb including ( %) with blood cultures positive. only five specimens had detectable lps, including two with a gnb-positive culture specimen, and three were lps-positive without gnb in any culture. prevalence of detectable lps was . % (ci: . %- . %). the frequency of detectable lps in antibiotic-naive plasma is too low to serve as a useful diagnostic test or therapeutic target in ed patients with severe sepsis. the data raise the question of whether post-antibiotic plasma may have a higher frequency of detectable lps. background: egdt is known to reduce mortality in septic patients. there is no evidence to date that delineates the role of using a risk stratification tool, such as the mortality in emergency department sepsis (meds) score, to determine which subgroups of patients may have a greater benefit with egdt. objectives: our objective was to determine if our egdt protocol differentially affects mortality based on the severity of illness using meds score. methods: this study is a retrospective chart review of patients, conducted at an urban tertiary care center, after implementing an egdt protocol on july , (figure) . this study compares in-hospital mortality, length of stay (los) in icu, and los in ed between the control group ( patients from / / - / / ) and the postimplementation group ( patients from / / - / / ), using meds score as a risk stratification tool. inclusion criteria: patients who presented to our ed with a suspected infection, and two or more sirs criteria, a map< mmhg, a sbp< mmol/l. exclusion criteria: age< , death on arrival to ed, dnr or dni, emergent surgical intervention, or those with an acute myocardial infarction or chf exacerbation. a two-sample t-test was used to show that the mean age and number of comorbidities was similar between the control and study groups (p = . and . respectively). mortality was compared and adjusted for meds score using logistic regression. the odds ratios and predicted probabilities of death are generated using the fitted logistic regression model. ed and icu los were compared using mood's median test. results: when controlling for illness severity using meds score, the relative risk (rr) of death with egdt is about half that of the control group (rr = . , % ci [ . - . ], p= . ). also, by applying meds score to risk stratify patients into various groups of illness severity, we found no specific groups where egdt is more efficacious at reducing the predicted probability of death (table ) . without controlling for meds score, there is a trend in reduction of absolute mortality by . % when egdt is used (control = . %, study = . %, p = . ). egdt leads to a . % reduction in the median los in icu (control = hours, study = hours, p = . ), without increasing los in ed (control = hours, study = hours, p = . ). conclusion: egdt is beneficial in patients with severe sepsis or septic shock, regardless of their meds score. background: in patients experiencing acute coronary syndrome (acs), prompt diagnosis is critical in achieving the best health outcome. while ecg analysis is usually sufficient to diagnose acs in cases of st elevation, acs without st elevation is reliably diagnosed through serial testing of cardiac troponin i (ctni). pointof-care testing (poct) for ctni by venipuncture has been proven a more rapid means to diagnosis than central laboratory testing. implementing fingerstick testing for ctni in place of standard venipuncture methods would allow for faster and easier procurement of patients' ctni levels, as well as increase the likelihood of starting a rapid test for ctni in the prehospital setting, which could allow for even earlier diagnosis of acs. objectives: to determine if fingerstick blood samples yield accurate and reliable troponin measurements compared to conventional venous blood draws using the i-stat poc device. methods: this experimental study was performed in the ed of a quaternary care suburban medical center between june-august . fingerstick blood samples were obtained from adult ed patients for whom standard (venipuncture) poc troponin testing was ordered. the time between fingerstick and standard draws was kept as narrow as possible. ctni assays were performed at the bedside using the i-stat (abbott point of care). results: samples from patients were analyzed by both fingerstick and standard ed poct methods (see table) . four resulted in cartridge error. compared to ''gold standard'' ed poct, fingerstick testing has a positive predictive value of %, negative predictive value of %, sensitivity of %, and specificity of %. no significant difference in ctni level was found between the two methods, with a nonparametric intraclass correlation coefficient of . ( % ci . - . , p-value < . ). conclusion: whole blood fingerstick ctni testing using the i-stat device is suitable for rapid evaluation of ctni level in prehospital and ed settings. however, results must be interpreted with caution if they are within a narrow territory of the cutoff for normal vs. elevated levels. additional testing on a larger sample would be beneficial. the practicality and clinical benefit of using fingerstick ctni testing in the ems setting must still be assessed. background: adjudication of diagnosis of acute myocardial infarction (ami) in clinical studies typically occurs at each site of subject enrollment (local) or by experts at an independent site (central). from from - , the troponin (ctn) element of the diagnosis was predicated on the local laboratories, using a mix of the th percentile reference ctn and roc-determined cutpoints. in , the universal definition of ami (ud-ami) defined it by the th percentile reference alone. objectives: to compare the diagnosis rates of ami as determined by local adjudication vs. central adjudication using udami criteria. methods: retrospective analysis of data from the myeloperoxidase in the diagnosis of acute coronary syndromes (acs) study (midas), an -center prospective study with enrollment from / / to / / of patients with suspected acs presenting to the ed < hours after symptom onset and in whom serial ctn and objective cardiac perfusion testing was planned. adjudication of acs was done by single local principal investigators using clinical data and local ctn cutpoints from different ctn assays, and applying the definition. central adjudication was done after completion of the midas primary analysis using the same data and local ctn assay, but by experts at three different institutions, using the udami and the manufacturer's th percentile ctn cutpoint, and not blinded to local adjudications. discrepant dignoses were resolved by consensus. local vs. central ctn cutpoints differed for six assays, with central cutpoints lower in all. statistics were by chi-square and kappa. results: excluding cases deemed indeterminate by central adjudication, cases were successfully adjudicated. local adjudication resulted in ami ( . % of total) and non-ami; central adjudication resulted in ( . %) ami and non-ami. overall, local diagnoses ( %) were either changed from non-ami to ami or ami to non-ami (p < . ). interrater reliability across both methods was found to be kappa = . (p < . ). for acs diagnosis, local adjudication identified acs cases ( %) and non-acs, while central adjudication identified acs ( %) and non-acs. overall, local diagnoses ( %) were either changed from non-acs to acs or acs to non-acs (p < . ). interrater reliability found kappa = . (p < . ). conclusion: central and local adjudication resulted in significantly different rates of ami and acs diagnosis. however, overall agreement of the two methods across these two diagnoses was acceptable. occur four times more often in cocaine users. biomarkers myeloperoxidase (mpo) and c-reactive protein (crp) have potential in the diagnosis of acs. objectives: to evaluate the utility of mpo and crp in the diagnosis of acs in patients presenting to the ed with cocaine-associated chest pain and compare the predictive value to nonusers. we hypothesized that these markers may be more sensitive for acs in nonusers given the underlying pathophysiology of enhanced plaque inflammation. methods: a secondary analysis of a cohort study of enrolled ed patients who received evaluation for acs at an urban, tertiary care hospital. structured data collection at presentation included demographics, chest pain history, lab, and ecg data. subjects included those with self-reported or lab-confirmed cocaine use and chest pain. they were matched to controls based on age, sex, and race. our main outcome was diagnosis of acs at index visit. we determined median mpo and crp values, calculated maximal auc for roc curves, and found cut-points to maximize sensitivity and specificity. data are presented with % ci. results: overall, patients in the cocaine positivegroup and patients in the nonusers group had mpo and crp levels measured. patients had a median age of (iqr, ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) , % black or african american, and % male (p > . between groups). fifteen patients were diagnosed with acs: patients in the cocaine group and in the nonusers group. comparing cocaine users to nonusers, there was no difference in mpo (median [iqr, ] v ng/ml; p = . ) or crp ( [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] v [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] mg/l; p = . ). the auc for mpo was . ( % ci . - . ) v . ( % ci . - . ). the optimal cut-point to maximize sensitivity and specificity was ng/ml which gave a sensitivity of . and specificity of . . using this cutpoint, % v % of acs in cocaine users vs the nonusers would be identified. the auc for crp was . ( % ci . - . ) in cocaine users vs . ( % ci . - . ) in nonusers. the optimal cut point was . mg/l with a sensitivity of . and specificity of . . using this cutpoint, % v % of acs in cocaine users and nonusers would have been identified. conclusion: the diagnostic accuracy of mpo and crp is not different in cocaine users than nonusers and does not appear to have sufficient discriminatory ability in either cohort. results: hrs of moderate pe caused a significant decrease in rv heart function in rats treated with the solvent for bay - : peak systolic pressure (psp) decreased from ± . mmhg, control to ± . , pe, +dp/dt decreased from ± mmhg/sec to ± , -dp/dt decreased from ) ± mmhg/sec to ) ± . treatment of rats with bay - significantly improved all three indices of rv heart function (psp ± . , +dp/dt ± , -dp/dt ) ± ). hrs of severe pe also caused significant rv dysfunction (psp ± , -dp/dt ) ± ) and treatment with bay - produced protection of rv heart function (psp ± , -dp/dt ) ± ) similar to the hr moderate pe model. conclusion: experimental pe produced significant rv dysfunction, which was ameliorated by treatment of the animals with the soluble guanylate cyclase stimulator, bay - . hospital of the university of pennsylvania, philadelphia, pa; cooper university hospital, camden, nj background: patients who present to the ed with symptoms of potential acute coronary syndrome (acs) can be safely discharged home after a negative coronary computerized tomographic angiography (cta). however, the duration of time for which a negative coronary cta can be used to inform decision making when patients have recurrent symptoms is unknown. objectives: we examined patients who received more than one coronary cta for evaluation of acs to determine whether they had disease progression, as defined by crossing the threshold from noncritical (< % maximal stenosis) to potentially critical disease. methods: we performed a structured comprehensive record search of all coronary ctas performed from to at a tertiary care health system. low-tointermediate risk ed patients who received two or more coronary ctas, at least one from an ed evaluation for potential acs, were identified. patients who were revascularized between scans were excluded. we collected demographic data, clinical course, time between scans, and number of ed visits between scans. record review was structured and done by trained abstractors. our main outcome was progression of coronary stenosis between scans, specifically crossing the threshold from noncritical to potentially critical disease. results: overall, patients met study criteria (median age , interquartile range [iqr] ( . - ); % female; % black). the median time between studies was . months (iqr, . patients did not have stenosis in any vessel on either coronary cta, two studies showed increasing stenosis of < %, and the rest showed ''improvement,'' most due to better imaging quality. no patient initially below the % threshold subsequently exceeded it ( %; % ci, - . %). patients also had varying numbers of ed visits (median number of visits , range - ), and numbers of ed visits for potentially cardiac complaints (median , range - ); were re-admitted for potentially cardiac complaints (for example, chest pain or shortness of breath), and received further provocative cardiac testing, all of which had negative results. conclusion: we did not find clinically significant disease progression within a year time frame in patients who had a negative coronary cta, despite a high number of repeat visits. this suggests that prior negative coronary cta may be able to be used to inform decision making within this time period. . - . ) compared to non tro ct patients. there was no significant difference in image quality between tro ct images and those of dedicated ct scans in any studies performing this comparison. similarly, there was no significant difference between tro ct and other diagnostic modalities in regards to length of stay or admission rate. when compared to conventional coronary angiography as the gold standard for evaluation of cad, tro ct had the following pooled diagnostic accuracy estimates: sensitivity . conclusion: tro chest ct is comparable to dedicated pe, coronary, or ad ct in regard to image quality, length of stay, and admission rate and is highly accurate for detecting cad. the utility of tro ct depends on the relative pre-test probabilities of the conditions being assessed and its role is yet to be clearly defined. tro ct, however, involves increased radiation exposure and contrast volume and for this reason clinicians should be selective in its use. background: coronary computed tomographic angiography (ccta) has high sensitivity, specificity, accuracy, and prognostic value for coronary artery disease (cad) and acs. however, how a ccta informs subsequent use of prescription medication is unclear. objectives: to determine if detection of critical or noncritical cad on ccta is associated with initiation of aspirin and statins for patients who presented to the ed with chest pain. we hypothesized that aspirin and statins would be more likely to be prescribed to patients with noncritical disease relative to those without any cad. methods: prospective cohort study of patients who received ccta as part of evaluation of chest pain in the ed or observation unit. patients were contacted and medical records were reviewed to obtain clinical follow-up for up to the year after ccta. the main outcome was new prescription of aspirin or statin. cad severity on ccta was graded as absent, mild ( % to %), moderate ( % to %), or severe ( ‡ %) stenosis. logistic regression was used to assess the association of stenosis severity to new medication prescription; covariates were determined a priori. results: patients who had ccta performed consented to participate in this study or met waiver of consent for record review only (median age, , % female, % black). median follow-up time was days, iqr - days. at baseline, % of the total cohort was already prescribed aspirin and % on statin medication. two hundred seventy nine ( %) patients were found to have stenosis in at least one vessel. in patients with absent, mild, moderate, and severe cad on ccta, aspirin was initiated in %, %, %, and %; statins were initiated in %, %, %, and % of patients. after adjustment for age, race, sex, hypertension, diabetes, cholesterol, tobacco use, and admission to the hospital after ccta, higher grades of cad severity were independently associated with greater post-ccta use of aspirin (or . per grade, % ci . - . , p < . ) and statins (or . , % ci . - . , p < . ). conclusion: greater cad severity on ccta is associated with increased medication prescription for cad. patients with noncritical disease are more likely than patients without any disease to receive aspirin and statins. future studies should examine whether these changes lead to decreased hospitalizations and improved cardiovascular health. background: hess et al. developed a clinical decision rule for patients with acute chest pain consisting of the absence of five predictors: ischemic ecg changes not known to be old, elevated initial or -hour troponin level, known coronary disease, ''typical'' pain, and age over . patients less than required only a single troponin evaluation. objectives: to test the hypothesis that patients less than years old without these criteria are at < % risk for major adverse cardiovascular events (mace) including death, ami, pci, and cabg. methods: we performed a secondary analysis of several combined prospective cohort studies that enrolled ed patients who received an evaluation for acs in an urban ed from to . cocaine users and stemi patients were excluded. structured data collection at presentation included demographics, pain description, history, lab, and ecg data for all studies. hospital course was followed daily. thirty-day follow up was done by telephone. our main outcome was -day mace using objective criteria. the secondary outcome was potential change in ed disposition due to application of the rule. descriptive statistics and % cis were used. results: of visits for potential acs, patients had a mean age of . ± . yrs; % were black and % female. there were patients ( . %) with -day cv events ( dead, ami, pci). sequential removal of patients in order to meet the final rule for patients less than excluded patients based upon: ischemic ecg changes not old (n = , % mace rate), elevated initial troponin level (n = , % mace), known coronary disease (n = , % mace), ''typical'' pain (n = , % mace), and age over (n = , . % mace) leaving patients less than with . % mace [ % ci, . - . %]. of this cohort, % were discharged home from the ed by the treating physician without application of this rule. adding a second negative troponin in patients - years old identified a group of patients with a . % rate of mace [ . - . ] and a % discharge rate. the hess rule appears to identify a cohort of patients at approximately % risk of -day mace, and may enhance discharge of young patients. however, even without application of this rule, the % of young patients at low risk are already being discharged home based upon clinical judgment. background: a clinical decision support system (cdss) incorporates evidence-based medicine into clinical practice, but this technology is underutilized in the ed. a cdss can be integrated directly into an electronic medical record (emr) to improve physician efficiency and ease of use. the christopher study investigators validated a clinical decision rule for patients with suspected pulmonary embolism (pe). the rule stratifies patients using wells' criteria to undergo either d-dimer testing or a ct angiogram (ct). the effect of this decision rule, integrated as a cdss into the emr, on ordering cts has not been studied. objectives: to assess the effect of a mandatory cdss on the ordering of d-dimers and cts for patients with suspected pe. methods: we assessed the number of cts ordered for patients with suspected pe before and after integrating a mandatory cdss in an urban community ed. physicians were educated regarding cdss use prior to implementation. the cdss advised physicians as to whether a negative d-dimer alone excluded pe or if a ct was required based on wells' criteria. the emr required physicians to complete the cdss prior to ordering the ct. however, physicians maintained the ability to order a ct regardless of the cdss recommendation. patients ‡ years of age presenting to the ed with a chief complaint of chest pain, dyspnea, syncope, or palpitations were included in the data analysis. we compared the proportion of d-dimers and cts ordered during the -month periods immediately before and after implementing the cdss. all physicians who worked in the ed during both time periods were included in the analysis. patients with an allergy to intravenous contrast agents, renal insufficiency, or pregnancy were excluded. results were analyzed using a chi-square test. results: a total of , patients were included in the data analysis ( pre-and post-implementation). cts were ordered for patients ( . %) in the pre-implementation group and patients ( . %) in the post-implementation group; p = . . a d-dimer was ordered for patients ( . %) in the pre-implementation group and patients ( . %) in the post-implementation group; p = . . in this single-center study, emr integration of a mandatory cdss for evaluation of pe did not significantly alter ordering patterns of cts and d-dimers. identification of patients with low-risk pulmonary emboli suitable for discharge from the emergency department mike zimmer, keith e. kocher university of michigan, ann arbor, mi background: recent data, including a large, multicenter randomized controlled trial, suggest that a low-risk cohort of patients diagnosed with pulmonary embolism (pe) exists who can be safely discharged from the ed for outpatient treatment. objectives: to determine if there is a similar cohort at our institution who have a low rate of complications from pe suitable for outpatient treatment. methods: this was a retrospective chart review at a single academic tertiary referral center with an annual ed volume of , patients. all adult ed patients who were diagnosed with pe during a -month period from / / through / / were identified. the pulmonary embolism severity index (pesi) score, a previously validated clinical decision rule to risk stratify patients with pe, was calculated. patients with high pesi (> ) were excluded. additional exclusion criteria included patients who were at high risk of complications from initiation of therapeutic anticoagulation and those patients with other clear indications for admission to the hospital. the remaining cohort of patients with low risk pe (pesi £ ) was included in the final analysis. outcomes were measured at and days after pe diagnosis and included death, major bleeding, and objectively confirmed recurrent venous thromboembolism (vte). results: during the study period, total patients were diagnosed with pe. there were ( %) patients categorized as ''low risk'' (pesi £ ), with removed because of various pre-defined exclusion criteria. of the remaining ( %) patients suitable for outpatient treatment, patients ( . %; % ci, . % - . %) had one or more negative outcomes by days. this included ( . %; % ci, % - . %) major bleeding events, ( . %; % ci, % - . %) recurrent vte, and ( . %; % ci, % - . %) deaths. none of the deaths were attributable to pe or anticoagulation. one patient suffered both a recurrent vte and died within days. both patients who died within days were transitioned to hospice care because of worsening metastatic burden. at days, there was bleeding event ( . %; % ci, % - . %), no recurrent vte, and no deaths. the average hospital length of stay for these patients was . days (sd ± . ). conclusion: over % of our patients diagnosed with pe in the ed may have been suitable for outpatient treatment, with % suffering a negative outcome within days and . % suffering a negative outcome within days. in addition, the average hospital length of stay for these patients was . days, which may represent a potential cost savings if these patients had been managed as outpatients. our experience supports previous studies that suggest the safety of outpatient treatment of patients diagnosed with pe in the ed. given the potential savings related to a decreased need for hospitalization, these results have health policy implications and support the feasibility of creating protocols to facilitate this clinical practice change. background: chest x-rays (cxrs) are commonly obtained on ed chest pain patients presenting with suspected acute coronary syndrome (acs). a recently derived clinical decision rule (cdr) determined that patients who have no history of congestive heart failure, have never smoked, and have a normal lung examination do not require a cxr in the ed. objectives: to validate the diagnostic accuracy of the hess cxr cdr for ed chest pain patients with suspected acs. methods: this was a prospective observational study of a convenience sample of chest pain patients over years old with suspected acs who presented to a single urban academic ed. the primary outcome was the ability of the cdr to identify patients with abnormalities on cxr requiring acute ed intervention. data were collected by research associates using the chart and physician interviews. abnormalities on cxr and specific interventions were predetermined, with a positive cxr defined as one with abnormality requiring ed intervention, and a negative cxr defined as either normal or abnormal but not requiring ed intervention. the final radiologist report was used as a reference standard for cxr interpretation. a second radiologist, blinded to the initial radiologist's report, reviewed the cxrs of patients meeting the cdr criteria to calculate inter-observer agreement. patients were followed up by chart review and telephone interview days after presentation. results: between january and august , patients were enrolled, of whom ( %) were excluded and ( . %) did not receive cxrs in the ed. of the remaining patients, ( %) met the cdr. the cdr identified all patients with a positive cxr (sensitivity = %, %ci - %). the cdr identified of the patients with a negative cxr (specificity = %, %ci - %). the positive likelihood ratio was . ( %ci . - . ). inter-observer agreement between radiologists was substantial (kappa = . , %ci . - . ). telephone contact was made with % of patients and all patient charts were reviewed at days. none had any adverse events related to a background: increasing the threshold to define a positive d-dimer in low-risk patients could reduce unnecessary computed tomographic pulmonary angiography (ctpa) for suspected pe. this strategy might increase rates of missed pe and missed pneumonia, the most common non-thromboembolic finding on ctpa that might not otherwise be diagnosed. objectives: measure the effect of doubling the standard d-dimer threshold for ' 'pe unlikely'' revised geneva (rgs) or wells' scores on the exclusion rate, frequency, and size of missed pe and missed pneumonia. methods: prospective enrollment at four academic us hospitals. inclusion criteria required patients to have at least one symptom or sign and one risk factor for pe, and have -channel ctpa completed. pretest probability data were collected in real time and the d-dimer was measured in a central laboratory. criterion standard for pe or pneumonia consisted of cpta interpretation by two independent radiologists combined with necessary treatment plan. subsegmental pe was defined as total vascular obstruction < %. patients were followed for outcome at days. proportions were compared with % cis. results: of patients enrolled, ( %) were pe+ and ( %) had pneumonia. with rgs£ and standard threshold (< ng/ml), d-dimer was negative in / ( %, % ci: - %), and / were pe+ (posterior probability . %, % ci: - . %). with rgs£ and a threshold < ng/ml, d-dimer was negative in / ( %, - %) and / ( . %, . - . %) were pe+, but / missed pes were subsegmental, and none had concomitant dvt. the posterior probability for pneumonia among patients with rgs&# ; and d-dimer< was / ( . %, - %) which compares favorably to the posterior probability of / ( . %, - %) observed with rgs& # ; and d-dimer< ng/ml. of the ( %) patients who also had plain film cxr, radiologists found an infiltrate in only . use of wells£ produced similar results as the rgs&# ; for exclusion rate and posterior probability of both pe and pneumonia. conclusion: doubling the threshold for a positive d-dimer with a pe unlikely pretest probability can significantly reduce ctpa scanning with a slightly increased risk of missed isolated subsegmental pe, and no increase in rate of missed pneumonia. background: the limitations of developing world medical infrastructure require that patients are transferred from health clinics only when the patient care needs exceed the level of care at the clinic and the receiving hospital can provide definitive therapy. to determine what type of definitive care service was sought when patients were transferred from a general outpatient clinic operating monday through friday from : am to : pm in rural haiti to urban hospitals in port-au-prince. methods: design -prospective observational review of all patients for whom transfer to a hospital was requested or for whom a clinic ambulance was requested to an off-site location to assist with patient care. setting -weekday, daytime only clinic in titanyen, haiti. participants/subjects -consecutive series of all patients for whom transfer to another health care facility or for whom an ambulance was requested during the time period of / / - / / and / / - / / . results: between / / - / / and / / - / / patients were identified who needed to be transferred to a higher level of care. sixteen patients ( . %) presented with medical complaints, ( . %) were trauma patients, ( . %) were surgical, and ( . %) were in the obstetric category. within these categories, patients were pediatric and non-trauma patients required blood transfusion. conclusion: while trauma services are often focused on in rural developing world medicine, the need for obstetric care and blood transfusion constituted six ( . %) cases in our sample. these patients raise important public health, planning, and policy questions relating to access to prenatal care and the need to better understand transfusion medicine utilization among rural haitian patients with non-trauma related transfusion needs. the data set is limited by sample size and single location of collection. another limitation of understanding the needs is that many patients may not present to the clinic for their health care needs in certain situations if they have knowledge that the resources to provide definitive care are unavailable. background: the practice of emergency medicine in japan has been unique in that emergency physicians are mostly engaged in critical care and trauma with a multi-specialty model. for the last decade with progress in medicine, an aging population with complicated problems, and institution of postgraduate general clinical training, the us model emergency medicine with single-specialty model has been emerging throughout japan. however, the current status is unknown. objectives: the objective of this study was to investigate the current status of implementation of the us model emergency medicine at emergency medicine training institutions accredited by the japanese association for acute medicine (jaam). methods: the er committee of the jaam, the most prestigious professional organization in japanese emergency medicine, conducted the survey by sending questionnaires to accredited emergency medicine training institutions. results: valid responses obtained from facilities were analyzed. us model em was provided in facilities ( % of facilities), either in full time ( hours a day, seven days a week; facilities) or in part time (less than hours a day; facilities). among these us model facilities, % have a number of beds between - . the annual number of ed visits was less than , in %, and % have ambulance transfers between , - , per year. the number of emergency physicians was less than in % of the facilities. postgraduate general clinical training was offered at us model ed in facilities, and ninety hospitals adopted us model em after , when a -year period of postgraduate general clinical training became mandatory for all medical graduates. sixty-four facilities provided a residency program to be a us model emergency physician, and another institutions were planning to establish it. conclusion: us model em has emerged and become commonplace in japan. the background including advance in medicine, aging population, and mandatory postgraduate general clinical training system are considered to be contributing factors. erkan gunay, ersin aksay, ozge duman atilla, nilay zorbalar, savas sezik tepecik research and training hospital, izmir, turkey background: workplace safety and occupational health problems are increasing issues especially in developing countries as a result of the industrial automatisation and technologic improvements. occupational injuries are preventable but they can occasionally cause morbidity and mortality resulting in work day loss and financial problems. hand injuries are one-third of all traumatic injuries and are the most injured parts after occupational accidents. objectives: we aim to evaluate patients with occupational upper extremity injuries for demographic characteristics, injury types, and work day loss. methods: trauma patients over years old admitted to our emergency department with an occupational upper extremity injury were prospectively evaluated from . . to . . . patients with one or more of digit, hand, forearm, elbow, humerus, and shoulder injuries were included. exclusion criteria were multitrauma, patient refusal to participate, and insufficient data. patients were followed up from the hospital information system and by phone for work day loss and final diagnosis. results: during the study period there were patients with an occupational upper extremity injury. total of ( . %) patients were included. patients were . % male, . % between the age to , and mean age was calculated . ± . years. . % of the patients were from the metal and machinery sector, and primary education was the highest education level for the . % of the patients. most injured parts were fingers with the highest rate for index finger and thumb. crush injury was the most common injury type. . % (n = ) of the patients were discharged after treatment in the emergency department. tendon injuries, open fractures, and high degree burns were the reasons for admission to clinics. mean work day loss was . ± . days and this increases for the patients with laboratory or radiologic studies, consultant evaluation, or admission. the - age group had a significantly lower work day loss average. conclusion: evaluating occupational injury characteristics and risks is essential for identifying preventive measures and actions. with the guidance of this study preventive actions focusing on high-risk sectors and patients may be the key factor for avoiding occupational injuries and creating safer workplace environments in order to reduce financial and public health problems. background: as emergency medicine (em) gains increased recognition and interest in the international arena, a growing number of training programs for emergency health care workers have been implemented in the developing world through international partnerships. objectives: to evaluate the quality and appropriateness of an internationally implemented emergency physician training program in india. methods: physicians participating in an internationally implemented em training program in india were recruited to participate in a program evaluation. a mixed methods design was used including an online anonymous survey and semi-structured focus groups. the survey assessed the research, clinical, and didactic training provided by the program. demographics and information on past and future career paths were also collected. the focus group discussions centered around program successes and challenges. results: fifty of eligible trainees ( %) participated in the survey. of the respondents, the vast majority were indian; % were female, and all were between the ages of and years (mean age years). all but two trainees ( %) intend to practice em as a career. one-third listed a high-income country first for preferred practice location and half listed india first. respondents directly endorsed the program structure and content, and they demonstrated gains in self-rated knowledge and clinical confidence over their years of training. active challenges identified include: ( ) insufficient quantity and inconsistent quality of indian faculty, ( ) administrative barriers to academic priorities, and ( ) persistent threat of brain drain if local opportunities are inadequate. conclusion: implementing an international emergency physician training program with limited existing local capacity is a challenging endeavor. overall, this evaluation supports the appropriateness and quality of this partnership model for em training. one critical challenge is achieving a robust local faculty. early negotiations are recommended to set educational priorities, which includes assuring access to em journals. attrition of graduated trainees to high-income countries due to better compensation or limited in-country opportunities continues to be a threat to long-term local capacity building. background: with an increasing frequency and intensity of manmade and natural disasters, and a corresponding surge in interest in international emergency medicine (iem) and global health (gh), the number of iem and gh fellowships is constantly growing. there are currently iem and gh fellowships, each with a different curriculum. several articles have proposed the establishment of core curriculum elements for fellowship training. to the best of our knowledge, no study has examined whether iem and gh fellows are actually fulfilling these criteria. objectives: this study sought to examine whether current iem and gh fellowships are consistently meeting these core curricula. methods: an electronic survey was administered to current iem and gh fellowship directors, current fellows, and recent graduates of a total of programs. survey respondents stated their amount of exposure to previously published core curriculum components: em system development, humanitarian assistance, disaster response, and public health. a pooled analysis comparing overall responses of fellows to those of program directors was performed using two-sampled t-test. results: response rates were % (n = ) for program directors and % (n = ) for current and recent fellows. programs varied significantly in terms of their emphasis on and exposure to six proposed core curriculum areas: em system development, em education development, humanitarian aid, public health, ems, and disaster management. only % of programs reported having exposure to all four core areas. as many as % of fellows reported knowing their curriculum only somewhat or not at all prior to starting the program. conclusion: many fellows enter iem and gh fellowships without a clear sense of what they will get from their training. as each fellowship program has different areas of curriculum emphasis, we propose not to enforce any single core curriculum. rather, we suggest the development of a mechanism to allow each fellowship program to present its curriculum in a more transparent manner. this will allow prospective applicants to have a better understanding of the various programs' curricula and areas of emphasis. background: advance warning of probable intensive care unit (icu) admissions could allow the bed placement process to start earlier, decreasing ed length of stay and relieving overcrowding conditions. however, physicians and nurses poorly predict a patient's ultimate disposition from the emergency department at triage. a computerized algorithm can use commonly collected data at triage to accurately identify those who likely will need icu admission. objectives: to evaluate an automated computer algorithm at triage to predict icu admission and -day in-hospital mortality. methods: retrospective cohort study at a , visit/ year level i trauma center/tertiary academic teaching hospital. all patients presenting to the ed between / / and / / were included in the study. the primary outcome measure was icu admission from the emergency department. the secondary outcome measure was -day all-cause in-hospital mortality. patients discharged or transferred before days were considered to be alive at days. triage data includes age, sex, acuity (emergency severity index), blood pressure, heart rate, pain scale, respiratory rate, oxygen saturation, temperature, and a nurse's free text assessment. a latent dirichlet allocation algorithm was used to cluster words in triage nurses' free text assessments into topics. the triage assessment for each patient is then represented as a probability distribution over these topics. logistic regression was then used to determine the prediction function. results: a total of , patients were included in the study. . % were admitted to the icu and . % died within days. these patients were then randomly allocated to train (n = , ; %) and test (n = , ; %) data sets. the area under the receiver operating characteristic curve (auc) when predicting icu background: at the saem annual meeting, we presented the derivation of two hospital admission prediction models adding coded chief complaint (ccc) data from a published algorithm (thompson et al. acad emerg med ; : - ) to demographic, ed operational, and acuity (emergency severity index (esi)) data. objectives: we hypothesized that these models would be validated when applied to a separate retrospective cohort, justifying prospective evaluation. methods: we conducted a retrospective, observational validation cohort study of all adult ed visits to a single tertiary care center (census: , /yr) ( / / - / / ). we downloaded from the center's clinical tracking system demographic (age, sex, race), ed operational (time and day of arrival), esi, and chief complaint data on each visit. we applied the derived ccc hospital admission prediction models (all identified ccc categories and ccc categories with significant odds of admission from multivariable logistic regression in the derivation cohort) to the validation cohort to predict odds of admission and compared to prediction models that consisted of demographic, ed operational, and esi data, adding each category to subsequent models in a stepwise manner. model performance is reported by areaunder-the-curve (auc) data and %ci. signs, pain level, triage level, -hour return, number of past visits in the previous year, injury, and one of chief complaint codes (representing % of all visits in the database). outputs for training included ordering of a complete blood count, basic chemistry (electrolytes, blood urea nitrogen, creatinine), cardiac enzymes, liver function panel, urinalysis, electrocardiogram, x-ray, computed tomography, or ultrasound. once trained, it was used on the nhamcs-ed database, and predictions were generated. predictions were compared with documented physician orders. outcomes included the percent of total patients who were correctly pre-ordered, sensitivity (the percent of patients who had an order that were correctly predicted), and the percent over-ordered. waiting time for correctly pre-ordered patients was highlighted, to represent a potential reduction in length of stay achieved by preordering. los for patients overordered was highlighted to see if over-ordering may cause an increase in los for those patients. unit cost of the test was also highlighted, as taken from the medicare fee schedule. physician times. however, during peak ed census times, many patients with completed tests and treatment initiated by triage await discharge by the next assigned physician. objectives: determine if a physician-led discharge disposition (dd) team can reduce the ed length of stay (los) for patients of similar acuity who are ultimately discharged compared to standard physician team assignment. methods: this prospective observational study was performed from / to / at an urban tertiary referral academic hospital with an annual ed volume of , visits. only emergency severity index level patients were evaluated. the dd team was scheduled weekdays from : until : . several ed beds were allocated to this team. the team was comprised of one attending physician and either one nurse and a tech or two nurses. comparisons were made between los for discharged patients originally triaged to the main ed side who were seen by the dd team versus the main side teams. time from triage physician to team physician, team physician to discharge decision time, and patient age were compared by unpaired t-test. differences were studied for number of patients receiving x-rays, ct scan, labs, and medications. results: dd team mean los in hours for discharged patients was shorter at . ( % ci: . - . , n = ) compared to . ( % ci: . - . , n = ) on the main side, p < . . the mean time from triage physician to dd team physician was . hours ( % ci: . - . , n = ) versus to . hours ( % ci: . - . , n = ) to main side physician, p < . . the dd team physician mean time to discharge decision was . hour ( % ci: . - . , n = ) compared to . hours ( % ci: . - . , n = ) for main side physician, p < . . the dd team patients' mean age was . years ( % ci: . - . , n = ) compared to main side patients' mean age of . years ( % ci: . - . , n = .) the dd team patients (n = ) received fewer x-rays ( % vs. %), ct scans ( % vs. %), labs ( % vs. %), and medications ( % vs. %) than main side patients (n = ), p < . for all compared. conclusion: the dd team complements the advanced triage process to further reduce los for patients who do not require extended ed treatment or observation. the dd team was able to work more efficiently because its patients tended to be younger and had fewer lab and imaging tests ordered by the triage physician compared to patients who were later seen on the ed main side. ed objectives: to evaluate the association between ed boarding time and the risk of developing hapu. methods: we conducted a retrospective cohort study using administrative data from an academic medical center with an adult ed with , annual patient visits. all patients admitted into the hospital through the ed / / - / / were included. development of hapu was determined using the standardized, national protocol for cms reporting of hapu. ed boarding time was defined as the time between an order for inpatient admission and transport of the patient out of the ed to an in-patient unit. we used a multivariate logistic regression model with development of a hapu as the outcome variable, ed boarding time as the exposure variable, and the following variables as covariates: age, sex, initial braden score, and admission to an intensive care unit (icu) from the ed. the braden score is a scale used to determine a patient's risk for developing a hapu based on known risk factors. a braden score is calculated for each hospitalized patient at the time of admission. we included braden score as a covariate in our model to determine if ed boarding time was a predictor of hapu independent of braden score. results: of , patients admitted to the hospital through the ed during the study period, developed a hapu during their hospitalization. clinical characteristics are presented in the table. per hour of ed boarding time, the adjusted or of developing a hapu was . ( % ci . - . , p = . ). a median of patients per day were admitted through the ed, accumulating hours of ed boarding time per day, with each hour of boarding time increasing the risk of developing a hapu by %. conclusion: in this single-center, retrospective study, longer ed boarding time was associated with increased risk of developing a hapu. queried ed and inpatient nurses and compared their opinions toward inpatient boarding. it also assessed their preferred boarding location if they were patients. objectives: this study queried ed and inpatient nurses and compared their opinions toward inpatient boarding. methods: a survey was administered to a convenience sample of ed and ward nurses. it was performed in a -bed academic medical center ( , admissions/yr) with a -bed ed ( , visits/yr). nurses were identified as ed or ward and whether they had previously worked in the ed. the nurses were asked if there were any circumstances where admitted patients should be boarded in the ed or inpatient hallways. they were also asked their preferred location if they were admitted as a patient. six clinical scenarios were then presented and their opinions on boarding queried. results: ninety nurses completed the survey; ( %) were current ed nurses (ced), ( %) had previously worked in the ed (ped). for the entire group ( %) believed admitted patients should board in the ed. overall, ( %) were opposed to inpatient boarding, with % of ced versus % of current ward (cw) nurses (p < . ) and % of ped versus % of nurses never having worked in the ed (ned) opposed (p < . ). if admitted as patients themselves, overall ( %) preferred inpatient boarding, with % of ced versus % of cw nurses (p < . ) and % of ped versus % ned nurses (p = . ) preferring inpatient boarding. for the six clinical scenarios, significant differences in opinion regarding inpatient boarding existed in all but two cases: a patient with stable copd but requiring oxygen and an intubated, unstable sepsis patient. conclusion: ward nurses and those who have never worked in the ed are more opposed to inpatient boarding than ed nurses and nurses who have worked previously in the ed. nurses admitted as patients seemed to prefer not being boarded where they work. ed and ward nurses seemed to agree that unstable or potentially unstable patients should remain in the ed. weeks. staff satisfaction was evaluated through pre/ post-shift and study surveys; administrative data (physician initial assessment (pia), length of stay (los), patients leaving without being seen (lwbs) and against medical advice [lama] ) were collected from an electronic, real-time ed information system. data are presented as proportions and medians with interquartile ranges (iqr); bivariable analyses were performed. results: ed physicians and nurses expected the intervention to reduce the los of discharged patients only. pia decreased during the intervention period ( vs minutes; p < . ). no statistically/clinically significant differences were observed in the los; however, there was a significant reduction in the lwbs ( . % to . % p = . ) and lama ( . % to . % p = . ) rates. while there was a reduction of approximately patients seen per physician in the affected ed area, the total number of patients seen on that unit increased by approximately patients/day. overall, compared to days when there was no extra shift, % of emergency physicians stated their workload decreased and % felt their stress level at work decreased. conclusion: while this study didn't demonstrate a reduction in the overall los, it did reduce pia times and the proportion of lwbs/lama patients. while physicians saw fewer patients during the intervention study period, the overall patient volume increased and satisfaction among ed physicians was rated higher. provider-and hospital-level variation in admission rates and -hour return admission rates jameel abualenain , william frohna , robert shesser , ru ding , mark smith , jesse m. pines the george washington university, washington, dc; washington hospital center, washington, dc background: decisions for inpatient versus outpatient management of ed patients are the most important and costliest decision made by emergency physicians, but there is little published on the variation in the decision to admit among providers or whether there is a relationship between a provider's admission rate and the proportion of their patients who return within hours of the initial visit and are subsequently admitted ( h-ra). objectives: we explored the variation in provider-level admission rates and h-ra rates, and the relationship between the two. methods: a retrospective study using data from three eds with the same information system over varying time periods: washington hospital center (whc) ( - ), franklin square hospital center (fshc) , and union memorial hospital (umh) . patients were excluded if left without being seen, left against medical advice, fast-track, psychiatric patients, and aged < years. physicians with < ed encounters or an admission rate < % were excluded. logistic regression was used to assess the relationship between physician-level h-ra and admission rates, adjusting for patient age, sex, race, and hospital. results: , ed encounters were treated by physicians. mean patient age was years sd , % male, and % black. admission rates differed between hospitals (whc = %, umh = %, and fshc = %), as did the h-ra (whc = . %, umh = . %, and fshc = . %). across all hospitals, there was great variation in individual physician admission rates ( . %- . %). the h-ra rates were quite low, but demonstrated a similar magnitude of individual variation ( . %- . %). physicians with the highest admission rate quintile had lower odds of h-ra (or . % ci . - . ) compared to the lowest admission rate quintile, after adjusting for other factors. no intermediate admission rate quintiles ( nd, rd, or th) were significantly different from the lowest admission rate quintile with regard to h-ra. conclusion: there is more than three-fold variation in individual physician admission rates indicating great variation among physicians in hospital admission rates and h-ra. the highest admitters have the lowest h-ra; however, evaluating the causes and consequences of such significant variation needs further exploration, particularly in the context of health reform efforts aimed at reducing costs. background: ed scribes have become an effective means to assist emergency physicians (eps) with clinical documentation and improve physician productivity. scribes have been most often utilized in busy community eds and their utility and functional integration into an academic medical center with resident physicians is unknown. objectives: to evaluate resident perceptions of attending physician teaching and interaction after introduction of scribes at an em residency training program, measured through an online survey. residents in this study were not working with the scribes directly, but were interacting indirectly through attending physician use of scribes during ed shifts. methods: an online ten question survey was administered to residents of a midwest academic emergency medicine residency program (pgy -pgy program, annual residents), months after the introduction of scribes into the ed. scribes were introduced as emr documentation support (epic , epic systems inc.) for attending eps while evaluating primary patients and supervising resident physicians. questions investigated em resident demographics and perceptions of scribes (attending physician interaction and teaching, effect on resident learning, willingness to use scribes in the future), using likert scale responses ( minimal, maximum) and a graduated percentage scale used to quantify relative values, where applicable. data were analyzed using kruskal-wallis and mann-whitney u tests. results: twenty-one of em residents ( %) completed the survey ( % male; % pgy , % pgy , % pgy ). four residents had prior experience with scribes. scribes were felt to have no effect on attending eps direct resident interaction time (mean score . , sd . ), time spent bedside teaching ( . , sd . ), or quality of teaching ( . , sd . ), as well as no effect on residents' overall learning process ( . , sd . ). however, residents felt positive about utilizing scribes at their future occupation site ( . , sd . ). no response differences were noted for prior experience, training level, or sex. conclusion: when scribes are introduced at an em residency training site, residents of all training levels perceive it as a neutral interaction, when measured in terms of perceived time with attending eps and quality of the teaching when scribes are present. the effect of introduction of an electronic medical record on resident productivity in an academic emergency department shawn london, christopher sala university of connecticut school of medicine, farmington, ct background: there are little available data which describe the effect of implementation of an electronic medical record (emr) on provider productivity in the emergency department, and no studies which, to our knowledge, address this issue pertaining to housestaff in particular. objectives: we seek to quantify the changes in provider productivity pre-and post-emr implementation to support our hypothesis that resident clinical productivity based on patients seen per hour will be negatively affected by emr implementation. methods: the academic emergency department at hartford hospital, the principle clinical site in the university of connecticut emergency medicine residency, sees over , patients on an annual basis. this environment is unique in that pre-emr, patient tracking and orders were performed electronically using the sunrise system (eclipsys corp) for over years prior to conversion to the allscripts ed emr in october, for all aspects of ed care. the investigators completed a random sample of days/evening/night/weekend shift productivity to obtain monthly aggregate productivity data (patients seen per hour) by year of training. results: there was an initial . % decrease of in productivity for pgy- residents on average from . patients per hour on average in the three blocks preceding activation of the emr to . patients seen per hour compared in the subsequent three prior blocks. pgy performance returned to baseline in the subsequent three months to . patients per hour. there was no change noted in patients seen per hour of pgy- and pgy- residents. conclusion: while many physicians tend to assume that emrs pose a significant barrier to productivity in the ed, in our academic emergency department, there was no lasting change on resident productivity based on the patients seen per hour metric. the minor decrease which did occur in pgy- residents was transient and was not apparent months after the emr was implemented. our experience suggests that decrease in the rate of patients seen per hour in the resident population should not be considered justification to delay or avoid implementation of an emr in the emergency department. emory university, atlanta, ga; children's healthcare of atlanta, atlanta, ga background: variation in physician practice is widely prevalent and highlights an opportunity for quality improvement and cost containment. monitoring resources used in the management of common pediatric emergency department (ed) conditions has been suggested as an ed quality metric. objectives: to determine if providing ed physicians with severity-adjusted data on resource use and outcomes, relative to their peers, can influence practice patterns. methods: data on resource use by physicians were extracted from electronic medical records at a tertiary pediatric ed for four common conditions in mid-acuity (emergency severity index level ): fever, head injury, respiratory illness, and gastroenteritis. condition-relevant resource use was tracked for lab tests (blood count, chemistry, crp), imaging (chest x-ray, abdominal x-ray, head ct scan, abdominal ct scan), intravenous fluids, parenteral antibiotics, and intravenous ondansetron. outcome measures included admission to hospital and ed length of stay (los); -hr return to ed (rr) was used as a balancing measure. scorecards were constructed using box plots to show physicians their practice patterns relative to peers (the figure shows an example of the scorecard for gatroenteritis for one physician, showing resources use rates for iv fluids and labs). blinded scorecards were distributed quarterly for five quarters using rolling-year averages. a pre/post-intervention analysis was performed with sep , as the intervention date. fisher's exact and wilcoxon rank sum tests were used for analysis. results: we analyzed , patient visits across two hospitals ( , pre-and , post-intervention), comprising . % of the total ed volume during the study period. patients were seen by physicians (mean patients/physician). the table shows overall physician practice in the pre-and post-intervention periods. significant reduction in resource use was seen for abdominal/pelvic ct scans, head ct scan, chest x-rays, iv ondansetron, and admission to hospital. ed los decreased from min to min (p = . ). there was no significant change in -hr return rate during the study period ( . % pre-, . % post-intervention). conclusion: feedback on comprehensive practice patterns including resource use and quality metrics can influence physician practice on commonly used resources in the ed. billboards, via iphone application, twitter, and text messaging. there is a paucity of data describing the accuracy of publically posted ed wait times. objectives: to examine the accuracy of publicly posted wait times of four emergency departments within one hospital system. methods: a prospective analysis of four ed-posted wait times in comparison to the wait times for actual patients. the main hospital system calculated and posted ed wait times every twenty minutes for all four system eds. a consecutive sample of all patients who arrived / over a -week period during july and august was included. an electronic tracking system identified patient arrival date and the actual incurred wait time. data consisted of the arrival time, actual wait time, hospital census, budgeted hospital census, and the posted ed wait time. for each ed the difference was calculated between the publicly posted ed wait time at the time of patient's arrival and the patient's actual ed wait time. the average wait times and average wait time error between the ed sites were compared using a two-tailed student's t-test. the correlation coefficient between the differences in predicted/ actual wait times was also calculated for each ed. results: there were wait times within the four eds included in the analysis. the average wait time (in minutes) at each facility was: . (± . ) for the main ed, . (± . ) for freestanding ed (fed) # , . (± . ) for fed # , and . (± . ) for the small community ed. the average wait time error (in minutes) for each facility was (± . ) for the main ed, (± . ) for fed # , (± . ) for fed # , and (± . ) for the community hospital ed. the results from each ed were statistically significant for both average wait time and average wait time error (p < . ). there was a positive correlation between the average wait time and average wait time error, with r-values of . , . , . , and . for the main ed, fed # , fed # , and the small community hospital ed, respectively. each correlation was statistically significant; however, no correlation was found between the number of beds available (budgeted-actual census) and average wait times. conclusion: publically posted ed wait times are accurate for facilities with less than ed visits per month. they are not accurate for eds with greater than visits per month. reduction of pre-analytic laboratory errors in the emergency department using an incentive-based system benjamin katz, daniel pauze, karen moldveen albany medical center, albany, ny background: over the last decade, there has been an increased effort to reduce medical errors of all kinds. laboratory errors have a significant effect on patient care, yet they are usually avoidable. several studies suggest that up to % of laboratory errors occur during the pre-or post-analytic phase. in other words, errors occur during specimen collection and transport or reporting of results, rather than during laboratory analysis itself. objectives: in an effort to reduce pre-analytic laboratory errors, the ed instituted an incentive-based program for the clerical staff to recognize and prevent specimen labeling errors from reaching the patient. this study sought to demonstrate the benefit of this incentive-based program. methods: this study examined a prospective cohort of ed patients over a three year period in a tertiary care academic ed with annual census of , . as part of a continuing quality improvement process, laboratory specimen labeling errors are screened by clerical staff by reconciling laboratory specimen label with laboratory requisition labels. the number of ''near-misses'' or mismatched specimens captured by each clerk was then blinded to all patient identifiers and was collated by monthly intervals. due to poor performance in , an incentive program was introduced in early by which the clerk who captured the most mismatched specimens would be awarded a $ gift card on a quarterly basis. the total number of missed laboratory errors was then recorded on a monthly basis. investigational data were analyzed using bivariate statistics. background: most studies on operational research have been focused in academic medical centers, which typically have larger volumes of patients and are located in urban metropolitan areas. as cms core measures in begin to compare emergency departments (eds) on treatment time intervals, especially length of stay (los), it is important to explore if any differences exist inherent to patient volume. objectives: the objective of this study is to look at differences in operational metrics based on annual patient census. the hypothesis is that treatment time intervals and operational metrics differ amongst these different categories. methods: the ed benchmarking alliance has collected yearly operational metrics since . as of , there are eds providing data across the united states. eds are stratified by annual volume for comparison in the following categories: < k, - k, - k, and over k. in this study, metrics for eds with < k visits per year were compared to those of different volumes, averaged from - . mean values were compared to < k visits as a reference point for statistical difference using t-tests to compare means with a p-value < . considered significant. results: as seen in the table, a greater percentage of high acuity of patients was seen in higher volume eds than in < k eds. the percentage of patients transferred to another hospital was higher in < k eds. a higher percentage arrived by ems and a higher percentage were admitted in higher volume eds when compared to < k visits. in addition, the median los for both discharged and admitted patients and percentage who left before treatment was complete (lbtc) were higher in the higher volume eds. conclusion: lower volume eds have lower acuity when compared to higher volume eds. lower volume eds have shorter median los and left before treatment complete percentages. as cms core measures require hospitals to report these metrics, it will be important to compare them based on volume and not in aggregate. does the addition of a hands-free communication device improve ed interruption times? amy ernst, steven j. weiss, jeffrey a. reitsema university of new mexico, albuquerque, nm background: ed interruptions occur frequently. recently a hands-free communication device (vocera) was added to a cell phone and a pager in our ed. objectives: the purpose of the present study was to determine whether this addition improved interruption times. our hypothesis was that the device would significantly decrease length of time of interruptions. methods: this study was a prospective cohort study of attending ed physician calls and interruptions in a level i trauma center with em residency. interruptions included phone calls, ekg interpretations, pages to resuscitation, and other miscellaneous interruptions (including nursing issues, laboratory, ems, and radiology). we studied a convenience sampling intended to include mostly evening shifts, the busiest ed times. length of time the interruption lasted was recorded. data were collected for a comparison group pre-vocera. three investigators collected data including seven different addendings' interruptions. data were collected on a form, then entered into an excel file. data collectors' agreement was determined during two additional four hour shifts to calculate a kappa statistic. spss was used for data entry and statistical analysis. descriptive statistics were used for univariate data. chi-square and mann whitney u nonparametric test were used for comparisons. results: of the total interruptions, % were phone calls, % were ekgs to be read, % were pages to resuscitation, and % miscellaneous. there were no significant differences in types of interruptions pre-vs. post-vocera. pre-vocera we collected hours of data with interruptions with a mean . per hour. post-vocera, hours of data were collected with interruptions with a mean . per hour. there was a significant difference in length of time of interruptions with an average of minutes pre-vocera vs. minutes post-vocera (p = . , diff . , % ci . - . ). vocera calls were significantly shorter than non-vocera calls ( vs minutes, p < . ). comparing data collectors for type of interruption during the same -hour shift resulted in a kappa (agreement) of . . conclusion: the addition of a hands-free communication device may improve interruptions by shortening call length. '' talk background: analyses of patient flow through the ed typically focus on metrics such as wait time, total length of stay (los), or boarding time. however, little is known about how much interaction a patient has with clinicians after being placed in a room, or what proportion of the in-room visit is also spent ''waiting,'' rather than directly interacting with care providers. objectives: the objective was to assess the proportion of time, relative to the time in a patient care area, that a patient spends actively interacting with providers during an ed visit. methods: a secondary analysis of audiotaped encounters of patients with one of four diagnoses (ankle sprain, back pain, head injury, laceration) was performed. the setting was an urban, academic ed. ed visits of adult patients were recorded from the time of room placement to discharge. audiotapes were edited to remove all downtime and non-patient-provider conversations. los and door-to-doctor times were abstracted from the medical record. the proportion of time the patient spent in direct conversation with providers (''talk-time'') was calculated as the ratio of the edited audio recording time to the time spent in a patient care area (talk-time = [edited audio time/(los -door-to-doctor)]). multiple linear regression controlling for time spent in patient care area, age, and sex was performed. results: the sample was % male with a mean age of years. median los: minutes (iqr: - ), median door-to-doctor: minutes (iqr: - ), median time spent in patient care area: minutes (iqr: - ). median time spent in direct conversation with providers was minutes (iqr: - ), corresponding to a talk-time percentage of . % (iqr: . - . %). there were no significant differences based on diagnosis. regression analysis showed that those spending a longer time in a patient care area had a lower percentage of talk time (b = ) . , p = . ). conclusion: although limited by sample size, these results indicate that approximately % of a patients' time in a care area is spent not interacting with providers. while some of the time spent waiting is out of the providers' control (e.g. awaiting imaging studies), this significant ''downtime'' represents an opportunity for both process improvement efforts to decrease downtime as well as the development of innovative patient education efforts to make the best use of the remaining downtime. degradation of emergency department operational data quality during electronic health record implementation michael j. ward, craig froehle, christopher j. lindsell university of cincinnati, cincinnati, oh background: process improvement initiatives targeted at operational efficiency frequently use electronic timestamps to estimate task and process durations. errors in timestamps hamper the use of electronic data to improve a system and may result in inappropriate conclusions about performance. despite the fact that the number of electronic health record (ehr) implementations is expected to increase in the u.s., the magnitude of this ehr-induced error is not well established. objectives: to estimate the change in the magnitude of error in ed electronic timestamps before and after a hospital-wide ehr implementation. methods: time-and-motion observations were conducted in a suburban ed, annual census , , after receiving irb approval. observation was conducted weeks pre-and weeks post-ehr implementation. patients were identified on entering the ed and tracked until exiting. times were recorded to the nearest second using a calibrated stopwatch, and are reported in minutes. electronic data were extracted from the patient-tracking system in use pre-implementation, and from the ehr post-implementation. for comparison of means, independent t-tests were used. chi-square and fisher's t-tests were used for proportions, as appropriate. results: there were observations; before and after implementation. the differences between observed times and timestamps were computed and found to be normally distributed. post-implementation, mean physician seen times along with arrival to bed, bed to physician, and physician to disposition intervals occurred before observation. physician seen timestamps were frequently incorrect and did not improve postimplementation. significant discrepancies (ten minutes or greater) from observed values were identified in timestamps involving disposition decision and exit from the ed. calculating service time intervals resulted in every service interval (except arrival to bed) having at least % of the times with significant discrepancies. it is notable that missing values were more frequent post-ehr implementation. conclusion: ehr implementation results in reduced variability of timestamps but reduced accuracy and an increase in missing timestamps. using electronic timestamps for operational efficiency assessment should recognize the magnitude of error, and the compounding of error, when computing service times. background: procedural sedation and analgesia is used in the ed in order to efficiently and humanely perform necessary painful procedures. the opposing physiological effects of ketamine and propofol suggest the potential for synergy, and this has led to interest in their combined use, commonly termed ''ketofol'', to facilitate ed procedural sedation. objectives: to determine if a : mixture of ketamine and propofol (ketofol) for ed procedural sedation results in a % or more absolute reduction in adverse respiratory events compared to propofol alone. methods: participants were randomized to receive either ketofol or propofol in a double-blind fashion according to a weight-based dosing protocol. inclusion criteria were age years or greater, and asa class - status. the primary outcome was the number and proportion of patients experiencing an adverse respiratory event according to pre-defined criteria (the ''quebec criteria''). secondary outcomes were sedation consistency, sedation efficacy, induction time, sedation time, procedure time, and adverse events. results: a total of patients were enrolled, per group. forty-three ( %) patients experienced an adverse respiratory event in the ketofol group compared to ( %) in the propofol group (difference %; % ci ) % to %; p = . ). thirty-eight ( %) patients receiving ketofol and ( %) receiving propofol developed hypoxia, of whom three ( %) ketofol patients and ( %) propofol patient received bag-valve-mask ventilation. sixty-five ( %) patients receiving ketofol and ( %) receiving propofol required repeat medication dosing or lightened to a ramsay sedation score of or less during their procedure (difference %; % ci % to %; p = . ). procedural agitation occurred in patients ( . %) receiving ketofol compared to ( %) receiving propofol (difference . %, % ci % to %). recovery agitation requiring treatment occurred in six patients ( %, % ci . % to . %) receiving ketofol. other secondary outcomes were similar between the groups. patients and staff were highly satisfied with both agents. conclusion: ketofol for ed procedural sedation does not result in a reduced incidence of adverse respiratory events compared to propofol alone. induction time, efficacy, and sedation time were similar; however, sedation depth appeared to be more consistent with ketofol. with propofol and its safety is well established. however, in cms enacted guidelines defining propofol as deep sedation and requiring administration by a physician. common edps practice had been one physician performing both the sedation and procedure. edps has proven safe under this one-physician practice. however, the guidelines mandated separate physicians perform each. objectives: the study hypothesis was that one-physician propofol sedation complication rates are similar to two-physician. methods: before and after, observational study of patients > years of age consenting to edps with propofol. edps completed with one physician were compared to those completed with two (separate physicians performing the sedation and the procedure). all data were prospectively collected. the study was completed at an urban level i trauma center. standard monitoring and procedures for edps were followed with physicians blinded to the objectives of this research. the frequency and incremental dosing of medication was left to the discretion of the treating physicians. the study protocol required an ed nurse trained in data collection to be present to record vital signs and assess for any prospectively defined complications. we used chi-square tests to compare the binary outcomes and asa scores across the time periods, and two-sample t-tests to test for differences in age between the two time periods. results: during the -year study period we enrolled patients: one-physician edps sedations and (- to ) also received bag-valve-mask ( ) [ . to ) ( ) [ . to ] (- to ) two-physician. all patients meeting inclusion criteria were included in the study. total adverse event rates were . % and . %, respectively (p = . ). the most common complications were hypotension and oxygen desaturation, and they respectively showed one-physcian rates of . % and . % and two-physician rates of . % and . % (p = . and . .) the unsuccessful procedure rates were . % vs . % (p = . ). conclusion: this study demonstrated no significant difference in complication rates for propofol edps completed by one physician as compared to two. background: overdose patients are often monitored using pulse oximetry, which may not detect changes in patients on high-flow oxygen. objectives: to determine whether changes in end-tidal carbon dioxide (etco ) detected by capnographic monitoring are associated with clinical interventions due to respiratory depression (crd) in patients undergoing evaluation for a decreased level of consciousness after a presumed drug overdose. methods: this was a prospective, observational study of adult patients undergoing evaluation for a drug overdose in an urban county ed. all patients received supplemental oxygen. patients were continuously monitored by trained research associates. the level of consciousness was recorded using the observer's assessment of alertness/sedation scale (oaa/s). vital signs, pulse oximetry, and oaa/s were monitored and recorded every minutes and at the time of occurrence of any crd. respiratory rate and etco were measured at five second intervals using a capno-stream monitor. crd included an increase in supplemental oxygen, the use of bag-valve-mask ventilations, repositioning to improve ventilation, and physical or verbal stimulus to induce respiration, and were performed at the discretion of the treating physicians and nurses. changes from baseline in etco values and waveforms among patients who did or did have a clinical intervention were compared using wilcoxon rank sum tests. results: patients were enrolled in the study (age , range to , % male, median oaas , range to ). suspected overdoses were due to opioids in , benzodiazepines in , an antipsychotic in , and others in . the median time of evaluation was minutes (range to ). crd occurred in % of patients, including an increase in o in %, repositioning in %, and stimulation to induce respiration in %. % had an o saturation of < % (median , range to ) and % had a loss of etco waveform at some time, all of whom had a crd. the median change in etco from baseline was mmhg, range to . among patients with crd it was mmhg, range to , and among patients with no crd it was mmhg, range to (p = . ). conclusion: the change in etco from baseline was larger in patients who required clinical interventions than in those who did not. in patients on high-flow oxygen, capnographic monitoring may be sensitive to the need for airway support. how reliable are health care providers in reporting changes in etco waveform anas sawas , scott youngquist , troy madsen , matthew ahern , camille broadwater-hollifield , andrew syndergaard , jared phelps , bryson garbett , virgil davis university of utah, salt lake city, ut; midwestern university, glendale, az background: etco changes have been used in procedural sedation analgesia (psa) research to evaluate subclinical respiratory depression associated with sedation regiments. objectives: to evaluate the accuracy of bedside clinician reporting of changes in etco . methods: this was a prospective, randomized, singleblind study conducted in ed setting from june until the present time. this study took place at an academic adult ed of a -bed ( in the ed) and a level i trauma center. subjects were randomized to receive either ketamine-propofol or propofol according to a standardized protocol. loss of etco waveforms for ‡ sec were recorded. following sedation, questionnaires were completed by the sedating physicians. digitally recorded etco waveforms were also reviewed by an independent physician and a trained research assistant (ra). to ensure the reliability of trained research assistants, we compared their analyses with the analyses of an independent physician for the first recordings. the target enrollment was patients in each group (n = total). statistics were calculated using sas statistical software. results: patients were enrolled; ( . %) are males and ( . %) are females. mean age was . ± . years. most participants did not have major risk factors for apnea or for further complications ( . % were asa class or ). etco waveforms were reviewed by ( . %) sedating physicians and ( . %) nurses at the bedside. there were ( . %) etco waveforms recordings, ( . %) were reviewed by an independent physician and ( %) were reviewed by an ra. a kappa test for agreement between independent physicians and ras was conducted on recordings and there were no discordant pairs (kappa = ). compared to sedating physicians, the independent physician was more likely to report etco wave losses (or . , % ci . - . ). compared to sedating physicians, ras were more likely to report etco wave losses (or . , % ci . - . ). conclusion: compared to sedating physicians at the bedside, independent physicians and ras were more likely to note etco waveform losses. an independent review of recorded etco waveform changes will be more reliable for future sedation research. background: comprehensive studies evaluating current practices of ed airway management in japan are lacking. many emergency physicians in japan still experience resistance regarding rapid sequence intubation (rsi). objectives: we sought to describe the success and complication rate of rsi with non-rsi. methods: design and setting: we conducted a multicenter prospective observational study using the jean registry of eds at academic and community hospitals in japan during between and . data fields include ed characteristics, patient and operator demographics, method of airway management, number of attempts, and adverse events. we defined non-rsi as intubation with sedation only, neuromuscular blockade only, and without medication. participants: all patients undergoing emergency intubation in ed were eligible for inclusion. cardiac arrest encounters were excluded from the analysis. primary analysis: we described rsi with non-rsi in terms of success rate on first attempt, within three attempts, and complication rate. we present descriptive data as proportions with % confidence intervals (cis). we report odds ratios (or) with % ci via chi-square testing. results: the database recorded intubations (capture rate %) and met the inclusion criteria. rsi was the initial method chosen in ( %) and non-rsi in ( %). use of rsi varied among institutes from % to %. success cases of rsi on first and within three attempts are intubations ( %, %ci %- %) and intubations ( %, %ci %- %), respectively. the success cases of non-rsi on first and within three attempts are intubations ( %, %ci %- %) and intubations ( %, %ci %- %). success rates of rsi on first and within three attempts are higher than non-rsi (or . , %ci . - . and or . , % ci . - . , respectively). we recorded complications in rsi ( %) and in non-rsi ( %). there is no significant difference of complication rate between rsi and non-rsi (or . , % ci . - . ). conclusion: in this multi-center prospective study in japan, we demonstrated a high degree of variation in use of rsi for ed intubation. additionally we found that success rate of rsi on first and within three attempts were both higher than non-rsi. this study has the limitation of reporting bias and confounding by indication. (originally submitted as a ''late-breaker.'') methods: this was a prospective, randomized, singleblind study conducted in the ed setting from june until the present time. this study took place at an academic adult ed of a -bed ( in the ed) and a level i trauma center. subjects were randomized to receive either ketamine-propofol or propofol according to a standardized protocol. etco waveforms were digitally recorded. etco changes were evaluated by the sedating physicians at the bedside. recorded waveforms were reviewed by an independent physician and a trained research assistant (ra). to ensure the reliability of trained ras, we computed a kappa test for agreement between the analysis of independent physicians and ras for the first recordings. a post-hoc analysis of the association between any loss, the number of losses, and total duration of loss of etco waveform and crp was performed. on review we recorded the absence or presence of loss of etco and the total duration in seconds of all lost etco episodes ‡ seconds. ors were calculated using sas statistical software. results: patients were enrolled; ( . %) are males and are ( . %) females. . % participants were asa class or . waveforms were reviewed by ( . %) sedating physicians. there were ( . %) waveforms recordings, ( . %) were reviewed by an independent physician and ( %) were reviewed by ras, where there were no discordant pairs (kappa = ). there were ( . %) crp events. any loss of etco was associated with a non-significant or of . ( % ci . - . ) for crp. however, the duration of etco loss was significantly associated with crp with an or of . ( % ci . - . ) for each second interval of lost etco . the number of losses was significantly associated with the outcome (or . , % ci . - . ). conclusion: defining subclinical respiratory depression as present or absent may be less useful than quantitative measurements. this suggests that risk is cumulative over periods of loss of etco , and the duration of loss may be a better marker of sedation depth and risk of complications than classification of any loss. background: ed visits present an opportunity to deliver brief interventions (bis) to reduce violence and alcohol misuse among urban adolescents at risk for future injury. previous analyses demonstrated that a brief intervention resulted in reductions in violence and alcohol consequences up to months. objectives: this paper describes findings examining the efficacy of bis on peer violence and alcohol misuse at months. methods: patients ( - yrs) at an ed reporting past year alcohol use and aggression were enrolled in the rct, which included computerized assessment, and randomization to control group or bi delivered by a computer (cbi) or therapist assisted by a computer (tbi). baseline and months included violence (peer aggression, peer victimization, violence related consequences) and alcohol (alcohol misuse, binge drinking, alcohol-related consequences). results: adolescents were screened ( % participation). of those, screened positive for violence and alcohol use and were randomized; % completed -month follow-up. as compared to the control group, the tbi group showed significant reductions in peer aggression (p < . ) and peer victimization (p < . ) at months. bi and control groups did not differ on alcohol-related variables at months. conclusion: evaluation of the saferteens intervention one year following an ed visit provides support for the efficacy of computer-assisted therapist brief intervention for reducing peer violence. violence against ed health care workers: a -month experience terry kowalenko , donna gates , gordon gillespie , paul succop university of michigan, ann arbor, mi; university of cincinnati, cincinnati, oh background: health care (hc) support occupations have an injury rate nearly times that of the general sector due to assaults, with doctors and nurses nearly times greater. studies have shown that the ed is at greatest risk of such events compared to other hc settings. objectives: to describe the incidence of violence in ed hc workers over months. specific aims were to ) identify demographic, occupational, and perpetrator factors related to violent events; ) identify the predictors of acute stress response in victims; and ) identify predictors of loss of productivity after the event. methods: longitudinal, repeated methods design was used to collect monthly survey data from ed hc workers (w) at six hospitals in two states. surveys assessed the number and type of violent events, and feelings of safety and confidence. victims also completed specific violent event surveys. descriptive statistics and a repeated measure linear regression model were used. results: ed hcws completed monthly surveys, and violent events were reported. the average per person violent event rate per months was . . events were physical threats ( . per person in months). events were assaults ( . per person in months). violent event surveys were completed, describing physical threats and assaults with % resulting in injuries. % of the physical threats and % of the assaults were perpetrated by men. comparing occupational groups revealed significant differences between nurses and physicians for all reported events (p = . ), with the greatest difference in physical threats (p = . ). nurses felt less safe than physicians (p = . ). physicians felt more confident than nurses in dealing with the violent patient (p = . ). nurses were more likely to experience acute stress than physicians (p < . ). acute stress significantly reduced productivity in general (p < . ), with a significant negative effect on ''ability to handle/ manage workload'' (p < . ) and ''ability to handle/ manage cognitive demands'' (p < . ). conclusion: ed hcws are frequent victims of violence perpetrated by visitors and patients. this violence results in injuries, acute stress, and loss of productivity. acute stress has negative consequences on the workers' ability to perform their duties. this has serious potential consequences to the victim as well as the care they provide to their patients. a randomized controlled feasibility trial of vacant lot greening to reduce crime and increase perceptions of safety eugenia c. garvin, charles c. branas perelman school of medicine at the university of pennsylvania, philadelphia, pa background: vacant lots, often filled with trash and overgrown vegetation, have been associated with intentional injuries. a recent quasi-experimental study found a significant decrease in gun crimes around vacant lots that had been greened compared with control lots. objectives: to determine the feasibility of a randomized vacant lot greening intervention, and its effect on police-reported crime and perceptions of safety. methods: for this randomized controlled feasibility trial of vacant lot greening, we partnered with the pennsylvania horticulture society (phs) to perform the greening intervention (cleaning the lots, planting grass and trees, and building a wooden fence around the perimeter). we analyzed police crime data and interviewed people living around the study vacant lots (greened and control) about perceptions of safety before and after greening. results: a total of sq ft of randomly selected vacant lot space was successfully greened. we used a master database of , vacant lots to randomly select vacant lot clusters. we viewed each cluster with the phs to determine which were appropriate to send to the city of philadelphia for greening approval. the vacant lot cluster highest on the random list to be approved by the city of philadelphia was designated the intervention site, and the next highest was designated the control site. overall, participants completed baseline interviews, and completed follow-up interviews after months. % of participants were male, % were black or african american, and % had a household income less than $ , . unadjusted difference-in-differences estimates showed a decrease in gun assaults around greened vacant lots compared to control. regression-adjusted estimates showed that people living around greened vacant lots reported feeling safer after greening compared to those who lived around control vacant lots (p < . ). conclusion: conducting a randomized controlled trial of vacant lot greening is feasible. greening may reduce certain gun crimes and make people feel safer. however, larger prospective trials are needed to further investigate this link. screening for violence identifies young adults at risk for return ed visits for injury abigail hankin-wei, brittany meagley, debra houry emory university, atlanta, ga background: homicide is the second leading cause of death among youth ages - . prior studies, in nonhealth care settings, have shown associations between violent injury and risk factors including exposure to community violence, peer behavior, and delinquency. objectives: to assess whether self-reported exposure to violence risk factors can be used to predict future ed visits for injuries. methods: we conducted a prospective cohort study in the ed of a southeastern us level i trauma center. patients aged - presenting for any chief complaint were included unless they were critically ill, incarcerated, or could not read english. recruitment took place over six months, by a trained research assistant (ra). the ra was present in the ed for - days per week, with shifts scheduled such that they included weekends and weekdays, over the hours from am- pm. patients were offered a $ gift card for participation. at the time of initial contact in the ed, patients completed a written questionnaire which included validated measures of the following risk factors: a) aggression, b) perceived likelihood of violence, c) recent violent behavior, d) peer behavior, e) community exposure to violence, and f) positive future outlook. at months following the initial ed visit, the participants' medical records were reviewed to identify any subsequent ed visits for injury-related complaints. data were analyzed with chi-square and logistic regression analyses. results: patients were approached, of whom patients consented. participants' average age was . years, with % female, and % african american. return visits for injuries were significantly associated with hostile/aggressive feelings (rr . , ci . , ) , self-reported perceived likelihood of violence (rr . , ci . , . ) , recent violent behavior (rr . , ci . , . ) , and peer group violence (rr . , ci . , . ) . these findings remained significant when controlling for participant sex. conclusion: a brief survey of risk factors for violence is predictive of return visit to the ed for injury. these findings identify a potentially important tool for primary prevention of violent injuries among young adults visiting the ed for both injury and non-injury complaints. background: sepsis is a commonly encountered disease in ed, with high mortality. while several clinical prediction rules (cpr) including meds, sirs, and curb- exist to facilitate clinicians in early recognition of risk of mortality for sepsis, most are of suboptimal performance. objectives: to derive a novel cpr for mortality of sepsis utilizing clinically available and objective predictors in ed. methods: we retrospectively reviewed all adult septic patients who visited the ed at a tertiary hospital during the year with two sets of blood cultures ordered by physicians. basic demographics, ed vital signs, symptoms and signs, underlying illnesses, laboratory findings, microbiological results, and discharge status were collected. multivariate logistic regressions were used to obtain a novel cpr using predictors with < . p-value tested in univariate analyses. the existing cprs were compared with this novel cpr using auc. results: of included patients, . % died in hospital, % had diabetes, % were older than years of age, % had malignancy, and % had positive blood bacterial culture tests. predisposing factors including history of malignancy, liver disease, immunosuppressed status, chronic kidney disease, congestive heart failure, and older than years of age were found to be associated with mortality (all p < . ). patients who developed mortality tended to have lower body temperature, narrower pulse pressure, higher percentage of red cell distribution width (rdw) and bandemia, higher blood urea nitrogen (bun), ammonia, and c-reactive protein level, and longer prothrombin time and activated partial thromboplastin time (aptt) (all p < . ). the most parsimonious cpr incorporating history of malignancy (or . , % ci . - . ), prolonged aptt ( . , . - . ), presence of bandemia ( . , . - . results: there was poor agreement between the physician's unstructured assessment used in clinical practice and the guidelines put forth by the aha/acc/acep task force. ed physicians were more likely to assess a patient as low risk ( %), while aha guidelines were more likely to classify patients as intermediate ( %) or high ( %) risk. however, when comparing the patient's final acs diagnosis and the relation to the risk assessment value, ed physicians proved better predictors of high-risk patients who in fact had acs, while the aha/acc/acep guidelines proved better at correctly identifying low-risk patients who did not have acs. conclusion: in the ed, physicians are far more efficient at correctly placing patients with underlying acs into a high-risk category, while established criteria may be overly conservative when applied to an acute care population. further research is indicated to look at ed physicians' risk stratification and ensuing patient care to assess for appropriate decision making and ultimate outcomes. compartative conclusion: the amuse score was more specific, but the wells score was more sensitive for acute lower limb dvt in this cohort. there is no significant advantage in using the amuse over the wells score in ed patient with suspected dvt. background: the direct cost of medical care is not accurately reflected in charges or reimbursement. the cost of boarding admitted patients in the ed has been studied in terms of opportunity costs, which are indirect. the actual direct effect on hospital expenses has not been well defined. objectives: we calculate the difference to the hospital in the cost of caring for an admitted patient in the ed and in a non-critical care in-patient unit. methods: time-directed activity-based costing (tdabc) has recently been proposed as a method of determining the actual cost of providing medical services. tdabc was used to calculate the cost per patient bed-hour both in the ed and for an in-patient unit. the costs include nursing, nursing assistants, clerks, attending and resident physicians, supervisory salaries, and equipment maintenance. boarding hours were determined from placement of admission order to transfer to in-patient unit. a convenience sample of consecutive non-critical care admissions was assessed to find the degree of ed physician involvement with boarded patients. results: the overhead cost per patient bed-hour in the ed was $ . . the equivalent cost per bed-hour inpatient was $ . , a differential of $ . . there were , boarding hours for medical-surgical patients in , a differential of $ , , . for the year. for the short-stay unit (no residents), the cost per patient hour was $ . and the boarding hours were , . this resulted in a differential cost of $ , . , a total direct cost to the hospital of $ , , . . review of consecutive admissions showed no orders placed by the ed physician after decision-toadmit. conclusion: concentration of resources in the ed means considerably higher cost per unit of care as compared to an in-patient unit. keeping admitted patients boarding in the ed results in expensive underutilization. this is exclusive of significant opportunity costs of lost revenue from walk-out and diverted patients. this study includes the cost of teaching attendings and residents (ed and in-patient) . in a non-teaching setting, the differential would be less and the cost of boarding would be shared by a fee-for-service ed physician group as well as the hospital. improving identification of frequent emergency department users using a regional health information background: frequent ed users consume a disproportionate amount of health care resources. interventions are being designed to identify such patients and direct them to more appropriate treatment settings. because some frequent users visit more than one ed, a health information exchange (hie) may improve the ability to identify frequent ed users across sites of care. objectives: to demonstrate the extent to which a hie can identify the marginal increase in frequent ed users beyond that which can be detected with data from a single hospital. methods: data from / / to / / from the new york clinical information exchange (nyclix), a hie in new york city that includes ten hospitals, were analyzed to calculate the number of frequent ed users ( ‡ visits in days) at each site and across the hie. results: there were , ( % of total patients) frequent ed users, with , ( %) of frequent users having all their visits at a single ed, while , ( %) frequent users were identified only after counting visits to multiple eds (table ) . site-specific increases varied from % to % (sd . ). frequent ed users accounted for % of patients, but for % of visits, averaging . visits per year, versus . visits per year for all other patients. . % of frequent users visited two or more eds during the study period, compared to . % of all other patients. conclusion: frequent ed users commonly visited multiple nyclix eds during the study period. the use of a hie helped identify many additional frequent users, though the benefits were lower for hospitals not located in the relative vicinity of another nyclix hospital. measures that take a community, rather than a single institution, into account may be more reflective of the care that the patient experiences. indocyanine background: due to their complex nature and high associated morbidity, burn injuries must be handled quickly and efficiently. partial thickness burns are currently treated based upon visual judgment of burn depth by the clinician. however, such judgment is only % accurate and not expeditious. laser doppler imaging (ldi) is far more accurate -nearly % after days. however, it is too cumbersome for routine clinical use. laser assisted indocyanine green angiography (laicga) has been indicated as an alternative for diagnosing the depth of burn injuries, and possesses greater utility for clinical translation. as the preferred outcome of burn healing is aesthetic, it is of interest to determine if wound contracture can be predicted early in the course of a burn by laic-ga. objectives: determine the utility of early burn analysis using laicga in the prediction of -day wound contracture. methods: a prospective animal experiment was performed using six anesthetized pigs, each with standardized wounds. differences in burn depth were created by using a . · . cm aluminum bar at three exposure times and temperatures: degrees c for seconds, degrees c for seconds, and degrees c for seconds. we have shown in prior validation experiments that these burn temperatures and times create distinct burn depths. laicga scanning, using lifecell spy elite, took place at hour, hours, hours, hours, and week post burn. imaging was read by a blinded investigator, and perfusion trends were compared with day post-burn contraction outcomes measured using imagej software. biopsies were taken on day to measure scar tissue depth. results: deep burns were characterized by a blue center indicating poor perfusion while more superficial burns were characterized by a yellow-red center indicating perfusion that was close to that of the normal uninjured adjacent skin (see figure) . a linear relationship between contraction outcome and burn perfusion could be discerned as early as hour post burn, peaking in strength at - hours post-burn. burn intensity could be effectively identified at hours post-burn, although there was no relationship with scar tissue depth. conclusion: pilot data indicate that laicga using lifecell spy has the ability to determine the depth of injury and predict the degree of contraction of deep dermal burns within - days of injury with greater accuracy than clinical scoring. the objectives: we hypothesize that real-time monitoring of an integrated electronic medical records system and the subsequent firing of a ''sepsis alert'' icon on the electronic ed tracking board results in improved mortality for patients who present to the ed with severe sepsis or septic shock. methods: we retrospectively reviewed our hospital's sepsis registry and included all patients diagnosed with severe sepsis or septic shock presenting to an academic community ed with an annual census of , visits and who were admitted to a medical icu or stepdown icu bed between june and october . in may an algorithm was added to our integrated medical records system that identifies patients with two sirs criteria and evidence of endorgan damage or shock on lab data. when these criteria are met, a ''sepsis alert'' icon (prompt) appears next to that patient's name on the ed tracking board. the system also pages an in-house, specially trained icu nurse who can respond on a prn basis and assist in the patient's management. months of intervention data are compared with months of baseline data. statistical analysis was via z-test for proportions. results: for ed patients with severe sepsis, the preand post-alert mortality was of ( %) and of ( %), respectively (p = . ; n = ). in the septic shock group, the pre-and post-alert mortality was of ( %) and of ( %), respectively (p = . ). with ed and inpatient sepsis alerts combined, the severe sepsis subgroup mortality was reduced from % to % (p = . ; n = ). conclusion: real-time ed ehr screening for severe sepsis and septic shock patients did not improve mortality. a positive trend in the severe sepsis subgroup was noted, and the combined inpatient plus ed data suggests statistical significance may be reached as more patients enter the registry. limitations: retrospective study, potential increased data capture post intervention, and no ''gold standard'' to test the sepsis alert sensitivity and specificity. ) . descriptive statistics were calculated. principal component analysis was used to determine questions with continuous response formats that could be aggregated. aggregated outcomes were regressed onto predictor demographic variables using multiple linear regression. results: / physicians completed the survey. physicians had a mean of . ± . years experience in the ed. . % were female. eight physicians ( %) reported never having used the tool, while . % of users estimated having used it more than five times. % of users cited the ''p'' alert on the etb as the most common notification method. most felt the ''p'' alert did not help them identify patients with pneumonia earlier (mean = . ± . ), but found it moderately useful in reminding them to use the tool ( . ± . ). physicians found the tool helpful in making decisions regarding triage, diagnostic studies, and antibiotic selection for outpatients and inpatients ( . ± . , . ± . , . ± . , and . ± . , respectively). they did not feel it negatively affected their ability to perform other tasks ( . ± . ). using multiple linear regression, neither age, sex, years experience, nor tool use frequency significantly predicted responses to questions about triage and antibiotic selection, technical difficulties, or diagnostic ordering. conclusion: ed physicians perceived the tool to be helpful in managing patients with pneumonia without negatively affecting workflow. perceptions appear consistent across demographic variables and experience. objectives: we seek to examine whether use of the salt device can provide reliable tracheal intubation during ongoing cpr. the dynamic model tested the device with human powered cpr (manual) and with an automated chest compression device (physio control lucas ). the hypothesis is that the predictable movement of an automated chest compression device will make tracheal intubation easier than the random movement from manual cpr. methods: the project was an experimental controlled trial and took place in the ed at a tertiary referral center in peoria, illinois. this project was an expansion arm of a similarly structured study using traditional laryngoscopy. emergency medicine residents, attending physicians, paramedics, and other acls-trained staff were eligible for participation. in randomized order, each participant attempted intubation on a mannequin using the salt device with no cpr ongoing, during cpr with a manual compression, and during cpr with an automatic chest compression. participants were timed in their attempt and success was determined after each attempt. results: there were participants in the trial. the success rates in the control group and the automated cpr group were both % ( / ) and the success rate in the manual cpr group was % ( / objectives: our primary hypothesis was that in fasting, asymptomatic subjects, larger fluid boluses would lead to proportional aortic velocity changes. our secondary endpoints were to determine inter-and intra-subject variation in aortic velocity measurements. methods: the authors performed a prospective randomized double-blinded trial using healthy volunteers. we measured the velocity time integral (vti) and maximal velocity (vmax) with an estimated - °pulsed wave doppler interrogation of the left ventricular outflow in the apical- cardiac window. three physicians reviewed optimal sampling gate position, doppler angle and verified the presence of an aortic closure spike. angle correction technology was not used. subjects with no history of cardiac disease or hypertension fasted for hours and were then randomly assigned to receive a normal saline bolus of ml/kg, ml/kg or ml/kg over minutes. aortic velocity profiles were measured before and after each fluid bolus. results: forty-two subjects were enrolled. mean age was ± (range to ) and mean body mass index . ± . (range . to ). mean volume (in ml) for groups receiving ml/kg, ml/kg, and ml/kg were , , and , respectively. mean baseline vmax (in cm/s) of the subjects was . ± . (range to ). mean baseline vti (in cm) was . ± . (range . to . ). pre-and post-fluid mean differences for vmax were ) . (± . ) and for vti . (± . ). aortic velocity changes in groups receiving ml/kg, ml/kg, and ml/kg were not statistically significant (see table) . heart rate changes were not significant. background: clinicians recognize that septic shock is a highly prevalent, high mortality disease state. evidence supports early ed resuscitation, yet care delivery is often inconsistent and incomplete. the objective of this study was to discover latent critical barriers to successful ed resuscitation of septic shock. objectives: clinicians recognize that septic shock is a highly prevalent, high mortality disease state. evidence supports early ed resuscitation, yet care delivery is often inconsistent and incomplete. the objective of this study was to discover latent critical barriers to successful ed resuscitation of septic shock. methods: we conducted five -minute risk-informed in-situ simulations. ed physicians and nurses working in the real clinical environment cared for a standardized patient, introduced into their existing patient workload, with signs and symptoms of septic shock. immediately after case completion clinicians participated in a minute debriefing session. transcripts of these sessions were analyzed using grounded theory, a method of qualitative analysis, to identify critical barrier themes. results: fifteen clinicians participated in the debriefing sessions: four attending physicians, five residents, five nurses, and one nurse practitioner. the most prevalent critical barrier themes were: anchoring bias and difficulty with cognitive framework adaptation as the patient progressed to septic shock (n = ), difficult interactions between the ed and ancillary departments (n = ), difficulties with physician-nurse commu-nication and teamwork (n = ), and delays in placing the central venous catheter due to perceptions surrounding equipment availability and the desire to attend to other competing interests in the ed prior to initiation of the procedure (n = and ). each theme was represented in at least four of the five debriefing sessions. participants reported the in-situ simulations to be a realistic representation of ed sepsis care. conclusion: in-situ simulation and subsequent debriefing provides a method of identifying latent critical areas for improvement in a care process. improvement strategies for ed-based septic shock resuscitation will need to address the difficulties in shock recognition and cognitive framework adaptation, physician and nurse teamwork, and prioritization of team effort. the background: the association between blood glucose level and mortality in critically ill patients is highly debated. several studies have investigated the association between history of diabetes, blood sugar level, and mortality of septic patients; however, no consistent conclusion could be drawn so far. objectives: to investigate the association between diabetes and initial glucose level and in-hospital mortality in patients with suspected sepsis from the ed. methods: we conducted a retrospective cohort study that consisted of all adult septic patients who visited the ed at a tertiary hospital during the year with two sets of blood cultures ordered by physicians. basic demographics, ed vital signs, symptoms and signs, underlying illnesses, laboratory findings, microbiological results, and discharge status were collected. logistic regressions were used to evaluate the association between risk factors, initial blood sugar level, and history of diabetes and mortality, as well as the effect modification between initial blood sugar level and history of diabetes. results: a total of patients with available blood sugar levels were included, of whom % had diabetes, % were older than years of age, and % were male. the mortality was % ( % ci . - . %). patients with a history of diabetes tended to be older, female, and more likely to have chronic kidney disease, lower sepsis severity (meds score), and positive blood culture test results (all p < . ). patients with a history of diabetes tended to have lower in-hospital mortality after ed visits with sepsis, controlling for initial blood sugar level (aor . , % ci . - . , p = . ). initial normal blood sugar seemed to be beneficial compared to lower blood sugar level for in-hospital mortality, controlled history of diabetes, sex, severity of sepsis, and age (aor . , % ci . - . , p = . ). the effect modification of diabetes on blood sugar level and mortality, however, was found to be not statistically significant (p = . ). conclusion: normal initial blood sugar level in ed and history of diabetes might be protective for mortality of septic patients who visited the ed. further investigation is warranted to determine the mechanism for these effects. methods: this irb-approved retrospective chart review included all patients treated with therapeutic hypothermia after cardiac arrest during at an urban, academic teaching hospital. every patient undergoing therapeutic hypothermia is treated by neurocritical care specialists. patients were identified by review of neurocritical care consultation logs. clinical data were dually abstracted by trained clinical study assistants using a standardized data dictionary and case report form. medications reviewed during hypothermia were midazolam, lorazepam, propofol, fentanyl, cisatracurium, and vecuronium. results: there were patients in the cohort. median age was (range - years), % were white, % were male, and % had a history of coronary artery disease. seizures were documented by continuous eeg in / ( %), and / ( %) died during hospitalization. most, / ( %), received fentanyl, / ( %) received benzodiazepine pharmacotherapy, and / ( %) received propofol. paralytics were administered to / ( %) patients, / ( %) with cisatracurium and / ( %) with vecuronium. of note, one patient required pentobarbital for seizure management. conclusion: sedation and neuromuscular blockade are common during management of patients undergoing therapeutic hypothermia after cardiac arrest. patients in this cohort often received analgesia with fentanyl, and sedation with a benzodiazepine or propofol. given the frequent use of sedatives and paralytics in survivors of cardiac arrest undergoing hypothermia, future studies should investigate the potential effect of these drugs on prognostication and survival after cardiac arrest. background: the use of therapeutic hypothermia (th) is a burgeoning treatment modality for post-cardiac arrest patients. objectives: we performed a retrospective chart review of patients who underwent post cardiac arrest th at eight different institutions across the united states. our objective was to assess how th is currently being implemented in emergency departments and assess the feasibility of conducting more extensive th research using multi-institution retrospective data. methods: a total of charts with dates from - were sent for review by participating institutions of the peri-resuscitation consortium. of those reviewed, eight charts were excluded for missing data. two independent reviewers performed the review and the results were subsequently compared and discrepancies resolved by a third reviewer. we assessed patient demographics, initial presenting rhythm, time until th initiation, duration of th, cooling methods and temperature reached, survival to hospital discharge, and neurological status on discharge. results: the majority of cases of th had initial cardiac rhythms of asystole or pulseless electrical activity ( . %), followed by ventricular tachycardia or fibrillation ( . %), and in . % the inciting cardiac rhythm was unknown. time to initiation of th ranged from - minutes with a mean time of min (sd . ). length of th ranged from - minutes with a mean time of minutes (sd ). average minimum temperature achieved was . °c, with a range from . - . °c (sd . °c). of the charts reviewed, ( . %) of the patients survived to hospital discharge and ( . %) were discharged relatively neurologically intact. conclusion: research surrounding cardiac arrest has always been difficult given the time and location span from pre-hospital care to emergency department to intensive care unit. also, as witnessed cardiac arrest events are relatively rare with poor survival outcomes, very large sample sizes are needed to make any meaningful conclusions about th. our varied and inconsistent results show that a multi-center retrospective review is also unlikely to provide useful information. a prospective multi-center trial with a uniform th protocol is needed if we are ever to make any evidence-based conclusions on the utility of th for post-cardiac arrest patients. serum results: mean la was . , sd = . . mean age was . years old, sd = . . a statistically significant positive correlation was found between la and pulse, respiratory rate (rr), wbc, platelets, and los, while a significant negative correlation was seen with temperature and hco -. when two subjects were dropped as possible outliers with la > , it resulted in non-significant temperature correlation, but a significant negative correlation with age and bun was revealed. patients in the higher la group were more likely to be admitted (p = . ) and have longer los. of the discharged patients, there was no difference in mean la level between those who returned (n = , mean la of . , sd = . ) and those who did not (n = , mean la of . , sd = . ), p = . . furthermore, mean la levels for those with sepsis (n = , mean la of . , sd = . ) did not differ from those without sepsis (n = , mean la of . , sd = . ), p = . . conclusion: higher la in pediatric patients presenting to the ed with suspected infection correlated with increased pulse, rr, wbc, platelets, and decreased bun, hco -, and age. la may be predictive of hospitalization, but not of -day return rates or pediatric sepsis screening in the ed. background: mandibular fractures are one of the most frequently seen injuries in the trauma setting. in terms of facial trauma, madibular fractures account for - % of all facial bone fractures. prior studies have demonstrated that the use of a tongue blade to screen these patients to determine whether a mandibular fracture is present may be as sensitive as x-ray. one study showed the sensitivity and specificity of the test to be . % and . %, respectively. in the last ten years, high-resolution computed tomography (hct) has replaced panoramic tomography (pt) as the gold standard for imaging of patients with suspected mandibular fractures. this study determines if the tongue blade test (tbt) remains as sensitive a screening tool when compared to the new gold standard of ct. objectives: the purpose of the study was to determine the sensitivity and specificity of the tbt as compared to the new gold standard of radiologic imaging, hct. the question being asked: is the tbt still useful as a screening tool for patients with suspected mandibular fractures when compared to the new gold standard of hct? methods: design: prospective cohort study. setting: an urban tertiary care level i trauma center. subjects: this study took place from / / to / / in which any person suffering from facial trauma presented. intervention: a tbt was performed by the resident physician and confirmed by the supervising attending physician. ct facial bones were then obtained for the ultimate diagnosis. inter-rater reliability (kappa) was calculated, along with sensitivity, specificity, accuracy, ppv, npv, likelihood ratio (lr) (+), and likelihood ratio (lr) (-) based on a · contingency tables generated. results: over the study period patients were enrolled. inter-rater reliability was kappa = . (se + . ). the table demonstrates the outcomes of both the tbt and ct facial bones for mandibular fracture. the following parameters were then calculated based on the contingency table: sensitivity . (ci . - . ), specificity . (ci . - . ), ppv . (ci . - . ), npv . (ci . - . ), accuracy . , lr(+) . ), lr (-) . (ci . - . ). conclusion: the tbt is still a useful screening tool to rule out mandibular fractures in patients with facial trauma as compared to the current gold standard of hct. background: appendicitis is the most common surgical emergency occurring in children. the diagnosis of pediatric appendicitis is often difficult and computerized tomography (ct) scanning is utilized frequently. ct, although accurate, is expensive, time-consuming, and exposes children to ionizing radiation. radiologists utilize ultrasound for the diagnosis of appendicitis, but it may be less accurate than ct, and may not incorporate emergency physician (ep) clinical impression regarding degree of risk. objectives: the current study compared ep clinical diagnosis of pediatric appendicitis pre-and post-bedside ultrasonography (bus). methods: children - years of age were enrolled if their clinical attending physician planned to obtain a consultative ultrasound, ct scan, or surgical consult specific for appendicitis. most children in the study received narcotic analgesia to facilitate bus. subjects were initially graded for likelihood of appendicitis based on research physician-obtained history and physical using a visual analogue scale (vas). immediately subsequent to initial grading, research physicians performed a bus and recorded a second vas impression of appendicitis likelihood. two outcome measures were combined as the gold standard for statistical analysis. the post-operative pathology report served as the gold standard for subjects who underwent appendectomy, while post -week telephone follow-up was used for subjects who did not undergo surgery. various specific ultrasound measures used for the diagnosis of appendicitis were assessed as well. results: / subjects had pathology-proven appendicitis. one subject was pathology-negative post-appendectomy. of the subjects who did not undergo surgery, none had developed appendicitis at the post -week telephone follow-up. pre-bus sensitivity was % ( - %) while post-bus sensitivity was % ( - %). both pre-and post-bus specificity was % ( - %). pre-bus lr+ was ( - ), while post-bus lr+ was ( - ). pre-and post-bus lr-were . and . , respectively. bus changed the diagnosis for % of subjects ( - %). background: there are very little data on the normal distance between the glenoid rim and the posterior aspect of the humeral head in normal and dislocated shoulders. while shoulder x-rays are commonly used to detect shoulder dislocations, they may be inadequate, exacerbate pain in the acquisition of some views, and lead to delay in treatment, compared to bedside ultrasound evaluation. objectives: our objective was to compare the glenoid rim to humeral head distance in normal shoulders and in anteriorly dislocated shoulders. this is the first study proposing to set normal and abnormal limits. methods: subjects were enrolled in this prospective observation study if they had a chief complaint of shoulder pain or injury, and received a shoulder ultrasound as well as a shoulder x-ray. the sonographers were undergraduate students given ten hours of training to perform the shoulder ultrasound. they were blinded to the x-ray interpretation, which was used as the gold standard. we used a posterior-lateral approach, capturing an image with the glenoid rim, the humeral head, as well as the infraspinatus muscle. two parallel lines were applied to the most posterior aspect of the humeral head and the most posterior aspect of the glenoid rim. a line perpendicular to these lines was applied, and the distance measured. in anterior dislocations, a negative measurement was used to denote the fact that the glenoid rim is now posterior to the most posterior aspect of the humeral head. descriptive analysis was applied to estimate the mean and th to th interquartile range of normal and anteriorly dislocated shoulders. results: eighty subjects were enrolled in this study. there were six shoulder dislocations, however only four were anterior dislocations. the average distance between the posterior glenoid rim and the posterior humeral head in normal shoulders was . mm, with a th to th inter-quartile range of . mm to . mm. the distance in our four cases of anterior dislocation was ) mm, with a th to th interquartile range of ) mm to ) mm. conclusion: the distance between the posterior humeral head to posterior glenoid rim may be mm to mm in patients presenting to the ed with shoulder pain but no dislocation. in contrast, this distance in anterior dislocations was greater than ) mm. shoulder ultrasound may be a useful adjunct to x-ray for diagnosing anterior shoulder dislocations. conclusion: in this retrospective study, the presence of rv strain on focus significantly increases the likelihood of an adverse short term event from pulmonary embolism and its combination with hypotension performs similarly to other prognostic rules. background: burns are expensive and debilitating injuries, compromising both the structural integrity and vascular supply to skin. they exhibit a substantial potential to deteriorate if left untreated. jackson defined three ''zones'' to a burn. while the innermost coagulation zone and the outermost zone of hyperemia display generally predictable healing outcomes, the zone of stasis has been shown to be salvageable via clinical intervention. it has therefore been the focus of most acute therapies for burn injuries. while laser doppler imaging (ldi) -the current gold standard for burn analysis -has been % effective at predicting the need for second degree burn excision, its clinical translation is problematic, and there is little information regarding its ability to analyze the salvage of the stasis zone in acute injury. laser assisted indocyanine green dye angiography (laicga) also shows potential to predict such outcomes with greater clinical utility. objectives: to test the ability of ldi and laicga to predict interspace (zone of stasis) survival in a horizontal burn comb model. methods: a prospective animal experiment was performed using four pigs. each pig had a set of six dorsal burns created using a brass ''comb'' -creating four rectangular · mm full thickness burns separated by · mm interspaces. laicga and ldi scanning took place at hour, hours, hours, and week post burn using novadaq spy and moor ldi respectively. imaging was read by a blinded investigator, and perfusion trends were compared with interspace viability and contraction. burn outcomes were read clinically, evaluated via histopathology, and interspace contraction was measured using image j software. results: laicga data showed significant predictive potential for interspace survival. it was . % predictive at hours post burn, % predictive hours post burn, and % predictive days post burn using a standardized perfusion threshold. ldi imaging failed to predict outcome or contraction trends with any degree of reliability. the pattern of perfusion also appears to be correlated with the presence of significant interspace contraction at days, with an % adherence to a power trendline. ventions, isolation, testing, treatment, and ''other'' category intervention were identified. one intervention involving school closures was associated with a % decrease in pediatric ed visits for respiratory illness. conclusion: most interventions were not tested in isolation, so the effect of individual interventions was difficult to differentiate. interventions associated with statistically significant decreases in ed crowding were school closures, as well as interventions in all categories studied. further study and standardization of intervention input, process, and outcome measures may assist in identifying the most effective methods of mitigating ed crowding and improving surge capacity during an influenza or other respiratory disease outbreak. communication background: the link between extended shift lengths, sleepiness, and occupational injury or illness has been shown, in other health care populations, to be an important and preventable public health concern but heretofore has not been fully described in emergency medical services (ems objectives: to assess the effect of an ed-based computer screening and referral intervention for ipv victims and to determine what characteristics resulted in a positive change in their safety. we hypothesized that women who were experiencing severe ipv and/or were in contemplation or action stages would be more likely to endorse safety behaviors. methods: we conducted the intervention for female ipv victims at three urban eds using a computer kiosk to deliver targeted education about ipv and violence prevention as well as referrals to local resources. all adult english-speaking non-critically ill women triaged to the ed waiting room were eligible to participate. the validated universal violence prevention screening protocol was used for ipv screening. any who disclosed ipv further responded to validated questionnaires for alcohol and drug abuse, depression, and ipv severity. the women were assigned a baseline stage of change (precontemplation, contemplation, action, or maintenance) based on the urica scale for readiness to change behavior surrounding ipv. participants were contacted at week and months to assess a variety of pre-determined actions such as moving out, to prevent ipv during that period. statistical analysis (chi-square testing) was performed to compare participant characteristics to the stage of change and whether or not they took protective action. results: a total of , people were screened and disclosed ipv and participated in the full survey. . % of the ipv victims were in the precontemplative stage of change, and . % were in the contemplation stage. women returned at week of follow-up ( . %), and ( . %) women returned at months of followup. . % of those who returned at week, and % of those who returned at months took protective action against further ipv. there was no association between the various demographic characteristics and whether or not a woman took protective action. conclusion: ed-based kiosk screening and health information delivery is both a feasible and effective method of health information dissemination for women experiencing ipv. stage of change was not associated with actual ipv protective measures. objectives: we present a pilot, head-to-head comparison of x and x effectiveness in stopping a motivated person. the objective is to determine comparative injury prevention effectiveness of the newer cew. methods: four humans had metal cew probe pairs placed. each volunteer had two probe pairs placed (one pair each on the right and left of the abdomen/inguinal region). superior probes were at the costal margin, inches lateral of midline. inferior probes were vertically inferior at predetermined distances of , , , and inches apart. each volunteer was given the goal of slashing a target feet away with a rubber knife during cew exposure. as a means of motivation, they believed the exposure would continue until they reached the goal (in reality, the exposure was terminated once no further progress was made). each volunteer received one exposure from a x and a x cew. the exposure order was randomized with a -minute rest between them. exposures were recorded on a hi-speed, hi-resolution video. videos were reviewed and scored by six physician, kinesiology, and law officer experts using standardized criteria for effectiveness including degree of upper and lower extremity, and total body incapacitation, and degree of goal achievement. reviews were descriptively compared independently for probe spread distances and between devices. results: there were exposures ( pairs) for evaluation and no discernible, descriptive reviewer differences in effectiveness between the x and the x cews when compared. background: the trend towards higher gasoline prices over the past decade in the u.s. has been associated with higher rates of bicycle use for utilitarian trips. this shift towards non-motorized transportation should be encouraged from a physical activity promotion and sustainability perspective. however, gas price induced changes in travel behavior may be associated with higher rates of bicycle-related injury. increased consideration of injury prevention will be a critical component of developing healthy communities that help safely support more active lifestyles. objectives: the purpose of this analysis was to a) describe bicycle-related injuries treated in u.s. emergency departments between and and b) investigate the association between gas prices and both the incidence and severity of adult bicycle injuries. we hypothesized that as gas prices increase, adults are more likely to shift away from driving for utilitarian travel toward more economical non-motorized modes of transportation, resulting in increased risk exposure for bicycle injuries. methods: bicycle injury data for adults ( - years) were obtained from the national electronic injury surveillance system (neiss) database for emergency department visits between - . the relationship between national seasonally adjusted monthly rates of bicycle injuries, obtained by a seasonal decomposition of time series, and average national gasoline prices, reported by the energy information administration, was examined using a linear regression analysis. results: monthly rates of bicycle injuries requiring emergency care among adults increase significantly as gas prices rise (p < . , see figure) . an additional , adult injuries ( % ci - , ) can be predicted to occur each month in the u.s. (> , injuries annually) for each $ rise in average gasoline price. injury severity also increases during periods of high gas prices, with a higher percentage of injuries requiring admission. conclusion: increases in adult bicycle use in response to higher gas prices are accompanied by higher rates of significant bicycle-related injuries. supporting the use of non-motorized transportation will be imperative to address public health concerns such as obesity and climate change; however, resources must also be dedicated to improve bicycle-related injury care and prevention. background: this is a secondary analysis of data collected for a randomized trial of oral steroids in emergency department (ed) musculoskeletal back pain patients. we hypothesized that higher pain scores in the ed would be associated with more days out of work. objectives: to determine the degree to which days out of work for ed back pain patients are correlated with ed pain scores. methods: design: prospective cohort. setting: suburban ed with , annual visits. participants: patients aged - years with moderately severe musculoskeletal back pain from a bending or twisting injury £ days before presentation. exclusion criteria included nonmusculoskeletal etiology, direct trauma, motor deficits, and employer-initiated visits. observations: we captured initial and discharge ed visual analog pain scores (vas) on a - scale. patients were contacted approximately days after discharge and queried about the days out of work. we plotted days out of work versus initial vas, discharge vas, and change in vas and calculated correlation coefficients. using the bonferroni correction because of multiple comparisons, alpha was set at . . results: we analyzed patients for whom complete data were available. the mean age was ± years and % were female. the average initial and discharge ed pain scales were . ± . and . ± . , respectively. on follow-up, % of patients were back to work and % did not lose any days of work. for the plots of the days out of work versus the initial and discharge vas and the change in the vas, the correlation coefficients (r ) were . (p = . ), . (p = . ), and . (p = . ), respectively. conclusion: for ed patients with musculoskeletal back pain, we found no statistically significant correlation between days out of work and ed pain scores. background: conducted electrical weapons (cews) are common law enforcement tools used to subdue and repel violent subjects and, therefore, prevent further injury or violence from occurring in certain situations. the taser x is a new generation of cew that has the capability of firing two cartridges in a ''semi-automatic'' mode, and has a different electrical waveform and different output characteristics than older generation technology. there have been no data presented on the human physiologic effects of this new generation cew. objectives: the objective of this study was to evaluate the human physiologic effects of this new cew. methods: this was a prospective, observational study of human subjects. an instructor shot subjects in the abdomen and upper thigh with one cartridge, and subjects received a -second exposure from the device. measured variables included: vital signs, continuous spirometry, pre-and post-exposure ecg, intra-exposure echocardiography, venous ph, lactate, potassium, ck, and troponin. results: ten subjects completed the study (median age . , median bmi . , % male). there were no important changes in vital signs or in potassium. the median increase in lactate during the exposure was . , range . to . . the median change in ph was ) . , range ) . to . . no subject had a clinically relevant ecg change, evidence of cardiac capture, or positive troponin up to hours after exposure. the median change in creatine kinase (ck) at hours was , range ) to . there was no evidence of impairment of breathing by spirometry. baseline median minute ventilation was . , which increased to . during the exposure (p = . ), and remained elevated at . post-exposure (p = . ). conclusion: we detected a small increase in lactate and decrease in ph during the exposure, and an increase in ck hours after the exposure. the physiologic effects of the x device appear similar to previous reports for ecd devices. use background: public bicycle sharing (bikeshare) programs are becoming increasingly common in the us and around the world. these programs make bicycles easily accessible for hourly rental to the public. there are currently active bikeshare programs in cities in the us, and more than programs are being developed in cities including new york and chicago. despite the importance of helmet use, bikeshare programs do not provide the opportunity to purchase or rent helmets. while the programs encourage helmet use, no helmets are provided at the rental kiosks. objectives: we sought to describe the prevalence of helmet use among adult users of bikeshare programs and users of personal bicycles in two cities with recently introduced bicycle sharing programs (boston, ma and washington, dc). methods: we performed a prospective observational study of bicyclists in boston, ma and washington, dc. trained observers collected data during various times of the day and days of the week. observers recorded the sex of the bicycle operator, type of bicycle, and helmet use. all bicycles that passed a single stationary location in any direction for a period of between and minutes were recorded. data are presented as frequencies of helmet use by sex, type of bicycle (bikeshare or personal), time of the week (weekday or weekend), and city. logistic regression was used to estimate the odds ratio for helmet use controlling for type of bicycle, sex, day of week, and city. results: there were observation periods in two cities at locations. , bicyclists were observed. there were ( . %) bicylists riding bikeshare bicycles. overall helmet use was . %, although helmet use varied significantly with sex, day of use, and type of bicycle (see figure) . bikeshare users were helmeted at a lower rate compared to users of personal bicycles ( . % vs . %). logistic regression, controlling for type of bicycle, sex, day of week, and city demonstrate that bikeshare users had higher odds of riding unhelmeted (or . , % ci . - . ). women had lower odds of riding unhelmeted (or . , . - . ), while weekend riders were more likely to ride unhelmeted (or . , . - . ). conclusion: use of bicycle helmets by users of public bikeshare programs is low. as these programs become more popular and prevalent, efforts to increase helmet use among users should increase. background: abusive head trauma (aht) represents one of the most severe forms of traumatic brain injury (tbi) among abused infants with % mortality. young adult males account for % of the perpetrators. most aht prevention programs are hospital-based and reach a predominantly female audience. there are no published reports of school-based aht prevention programs to date. objectives: . to determine whether a high schoolbased aht educational program will improve students' knowledge of aht and parenting skills. . to evaluate the feasibility and acceptability of a school-based aht prevention program. methods: this program was based on an inexpensive commercially available program developed by the national center on shaken baby syndrome. the program was modified to include a -minute interactive presentation that teaches teenagers about aht, parenting skills, and caring for inconsolable crying infants. the program was administered in three high schools in flint, michigan during spring . student's knowledge was evaluated with a -item written test administered pre-intervention, post-intervention, and two months after program completion. program feasibility and acceptability were evaluated through interviews and surveys with flint area school social workers, parent educators, teachers, and administrators. results: in all, high school students ( % male) participated. of these, ( . %) completed the pretest and post-test with ( %) completing the twomonth follow-up test. the mean pre-intervention, postintervention, and two-month follow-up scores were %, %, and % respectively. from pre-test to posttest, mean score improved %, p < . . this improvement was even more profound in young males, whose mean post-test score improved by %, p < . . of the participating social workers, parent educators, teachers, and administrators, % ranked the program as feasible and acceptable. conclusion: students participating in our program showed an improvement in knowledge of aht and parenting skills which was retained after two months. teachers, social workers, parent educators, and school administrators supported the program. this local pilot program has the potential to be implemented on a larger scale in michigan with the ultimate goal of reducing aht amongst infants. will background: fear of litigation has been shown to affect physician practice patterns, and subsequently influence patient care. the likelihood of medical malpractice litigation has previously been linked with patient and provider characteristics. one common concern is that a patient may exaggerate symptoms in order to obtain monetary payouts; however, this has never been studied. objectives: we hypothesize that patients are willing to exaggerate injuries for cash settlements and that there are predictive patient characteristics including age, sex, income, education level, and previous litigation. methods: this prospective cross-sectional study spanned june to december , in a philadelphian urban tertiary care center. any patient medically stable enough to fill out a survey during study investigator availability was included. two closed-ended paper surveys were administered over the research period. standard descriptive statistics were utilized to report incidence of: patients who desired to file a lawsuit, patients previously having filed lawsuits, and patients willing to exaggerate the truth in a lawsuit for a cash settlement. chi-square analysis was performed to determine the relationship between patient characteristics and willingness to exaggerate injuries for a cash settlement. results: of surveys, were excluded due to incomplete data, leaving for analysis. the mean age was with a standard deviation of , and % were male. the incidence of patients who had the desire to sue at the time of treatment was %. the incidence of patients who had filed a lawsuit in the past was %. of those patients, % had filed multiple lawsuits. fifteen percent [ % ci - %] of all patients were willing to exaggerate injuries for cash settlement. sex and income were found to be statistically significant predictors of willingness to exaggerate symptoms: % of females vs. % of males were willing to exaggerate (p = . ), and % of people with income less than $ , /yr vs. % of those with income over $ , / yr were willing to exaggerate (p = . ). conclusion: patients at a philadelphian urban tertiary center admit to willingness to exaggerate symptoms for a cash settlement. willingness to exaggerate symptoms is associated with female sex and lower income. background: current data suggest that as many as % of patients presenting to the ed with syncope leave the hospital without a defined etiology. prior studies have suggested a prevalence of psychiatric disease as high as % in patients with syncope of unknown etiology. objectives: to determine whether psychiatric disease and substance abuse are associated with an increased incidence of syncope of unknown etiology. methods: prospective, observational, cohort study of consecutive ed patients ‡ presenting with syncope was conducted between / and / . patients were queried in the ed and charts reviewed about a history of psychiatric disease, use of psychiatric medication, substance abuse, and duration. data were analyzed using sas with chi-square and fisher's exact tests. results: we enrolled patients who presented to the ed after syncope, of whom did not have an identifiable etiology for their syncopal event. . % of those without an identifiable etiology were male. ( %) patients had a history of or current psychiatric disease ( % male), and patients ( %) had a history of or current substance abuse ( % male). among males with psychiatric disease, % had an unknown etiology of their syncopal event, compared to % of males without psychiatric disease (p = . ). similarly, among all males with a history of substance abuse, % had an unknown etiology, as compared to % of males without a history of substance abuse (p = . ). a similar trend was not identified in elderly females with psychiatric disease (p = . ) or substance abuse (p = . ). however, syncope of unknown etiology was more common among both men and women under age with a history of substance abuse ( %) compared to those without a history of substance abuse ( %; p = . ). conclusion: our results suggest that psychiatric disease and substance abuse are associated with increased incidence of syncope of unknown etiology. patients evaluated in the ed or even hospitalized with syncope of unknown etiology may benefit from psychiatric screening and possibly detoxification referral. this is particularly true in men. (originally submitted as a ''late-breaker.'') scope background: after discharge from an emergency department (ed), pain management often challenges parents, who significantly under-treat their children's pain. rapid patient turnover and anxiety make education about home pain treatment difficult in the ed. video education standardizes information and circumvents insufficient time and literacy. objectives: to evaluate the effectiveness of a -minute instructional video for parents that targets common misconceptions about home pain management. methods: we conducted a randomized, double-blinded clinical trial of parents of children ages - years who presented with a painful condition, were evaluated, and discharged home in june and july . parents were randomized to a pain management video or an injury prevention control video. primary outcome was the proportion of parents who gave pain medication at home. these data were recorded in a home pain diary and analyzed using a chi-square test. parents' knowledge about pain treatment was tested before, immediately following, and days after intervention. mcnemar's test statistic determined odds that knowledge correlated with the intervention group. results: parents were enrolled: watched the pain education video, and the control video. . % completed follow up, providing information about home pain education use. significantly more parents provided at least one dose of pain medication to their children after watching the educational video: % vs. % (difference %, % ci . %, . %). the odds the parent had correct knowledge about pain treatment significantly improved immediately following the educational video for knowledge about pain scores (p = . ), the effect of pain on function (p < . ), and pain medication misconceptions (p < . ). these significant differences in knowledge remained days after the video intervention. the educational video about home pain treatment viewed by parents significantly increased the proportion of children receiving pain medication at home and significantly improved knowledge about at-home pain management. videos are an efficient tool to provide medical advice to parents that improves outcomes for children. methods: this was a prospective, observational study of consecutive admitted cpu patients in a large-volume academic urban ed. cardiology attendings round on all patients and stress test utilization is driven by their recommendation. eligibility criteria include: age> , aha low/intermediate risk, nondynamic ecgs, and normal initial troponin i. patients > and with a history of cad or co-existing active medical problem were excluded. based on prior studies and our estimated cpu census and demographic distribution, we estimated a sample size of , patients in order to detect a difference in stress utilization of % ( -tailed, a = . , b = . ). we calculated a timi risk prediction score and a diamond & forrester (d&f) cad likelihood score on each patient. t-tests were used for univariate comparisons of demographics, cardiac comorbidities, and risk scores. logistic regression was used to estimate odds ratios (ors) for receiving testing based on race, controlling for insurance and either timi or d&f score. results: over months, , patients were enrolled. mean age was ± , and % ( % ci - ) were female. sixty percent ( % ci - ) were caucasian, % ( % ci - ) african american, and % ( % ci - ) hispanic. mean timi and d&f scores were . ( % ci . - . ) and % ( % ci - ). the overall stress testing rate was % ( % ci - ). after controlling for insurance status and timi or d&f scores, african american patients had significantly decreased odds of stress testing (or timi . ( % ci . - . ), or d&f . ( % ci . - . )). hispanics had significantly decreased odds of stress testing in the model controlling for d&f (or d&f . ( % ci . - . )). conclusion: this study confirms that disparities in the workup of african american patients in the cpu are similar to those found in the general ed and the outpatient setting. further investigation into the specific provider or patient level factors contributing to this bias is necessary. the outcomes for hf and copd were sae . %, . %; death . %, . %. we found univariate associations with sae for these walk test components: too ill to walk (both hf, copd p < . ); highest heart rate ‡ (hf p = . , copd p = . ); lowest sao < % (hf p = . , copd p = . ); borg score ‡ (hf p = . , copd p = . ); walk test duration £ minute (hf p = . . copd p = . ). after adjustment for multiple clinical covariates with logistic regression analyses, we found ''walk test heart rate ‡ '' had an odds ratio of . for hf patients and ''too ill to start the walk test'' had an odds ratio of . for copd patients. conclusion: we found the -minute walk test to be easy to administer in the ed and that maximum heart rate and inability to start the test were highly associated with adverse events in patients with exacerbations of hf and copd, respectively. we suggest that the -minute walk test be routinely incorporated into the assessment of hf and copd patients in order to estimate risk of poor outcomes. the objectives: the objective of this study was to investigate differences in consent rates between patients of different demographic groups who were invited to participate in minimal-risk clinical trials conducted in an academic emergency department. methods: this descriptive study analyzed prospectively collected data of all adult patients who were identified as qualified participants in ongoing minimal risk clinical trials. these trials were selected for this review because they presented minimal factors known to be associated background: increasing rates of patient exposure to computerized tomography (ct) raise questions about appropriateness of utilization, as well as patient awareness of radiation exposure. despite rapid increases in ct utilization and published risks, there is no national standard to employ informed consent prior to radiation exposure from diagnostic ct. use of written informed consent for ct (icct) in our ed has increased patient understanding of the risks, benefits, and alternatives to ct imaging. our team has developed an adjunct video educational module (vem) to further educate ed patients about the ct procedure. objectives: to assess patient knowledge and preferences regarding diagnostic radiation before and after viewing vem. methods: the vem was based on icct currently utilized at our tertiary care ed (census , patients/ year). icct is written at an th grade reading level. this fall, vem/icct materials were presented to a convenience sample of patients in the ed waiting room am- pm, monday-sunday. patients who were < years of age, critically ill, or with language barrier were excluded. to quantify the educational value of the vem, a six-question pretest was administered to assess baseline understanding of ct imaging. the patients then watched the vem via ipad (macintosh) and reviewed the consent form. an eight-question post-test was then completed by each subject. no phi were collected. pre-and post-test results were analyzed using mcnemar's test for individual questions and a paired t-test for the summed score (sas version . ). results: patients consented and completed the survey. the average pre-test score for subjects was poor, % correct. review of vem/icct materials increased patient understanding of medical radiation as evidenced by improved post-test score to %. mean improvement between tests was % (p < . ). % of subjects responded that they found the materials helpful, and that they would like to receive icct. conclusion: the addition of a video educational module improved patient knowledge regarding ct imaging and medical radiation as quantified by pre-and posttesting. patients in our study sample reported that they prefer to receive icct. by educating patients about the risks associated with ct imaging, we increase informed, shared decision making -an essential component of patient-centered care. does objectives: we sought to determine the relationship between patients' pain scores and their rate of consent to ed research. we hypothesized that patients with higher pain scores would be less likely to consent to ed research. methods: retrospective observational cohort study of potential research subjects in an urban academic hospital ed with an average annual census of approximately , visits. subjects were adults older than years with chief complaint of chest pain within the last hours, making them eligible for one of two cardiac biomarker research studies. the studies required only blood draws and did not offer compensation. two reviewers extracted data from research screening logs. patients were grouped according to pain score at triage, pain score at the time of approach, and improvement in pain score (triage score -approach score). the main outcome was consent to research. simple proportions for consent rates by pain score tertiles were calculated. two multivariate logistic regression analyses were performed with consent as outcome and age, race, sex, and triage or approach pain score as predictors. results: overall, potential subjects were approached for consent. patients were % caucasian, % female, and with an average age of years. six patients did not have pain scores recorded at all and did not have scores documented within hours of approach and were excluded from relevant analyses. overall, . % of patients consented. consent rates by tertiles at triage, at time of approach, and by pain score improvement are shown in tables and . after adjusting for age, race, and sex, neither triage (p = . ) nor approach (p = . ) pain scores predicted consent. conclusion: research enrollment is feasible even in ed patients reporting high levels of pain. patients with modest improvements in pain levels may be more likely to consent. future research should investigate which factors influence patients' decisions to participate in ed research. conclusion: in this multicenter study of children hospitalized with bronchiolitis neither specific viruses nor their viral load predicted the need for cpap or intubation, but young age, low birth weight, presence of apnea, severe retractions, and oxygen saturation < % did. we also identified that children requiring cpap or intubation were more likely to have mothers who smoked during pregnancy and a rapid respiratory worsening. mechanistic research in these high-risk children may yield important insights for the management of severe bronchiolitis. brigham & women's hospital, boston, ma background: siblings and children who share a home with a physically abused child are thought to be at high risk for abuse. however, rates of injury in these children are unknown. disagreements between medical and child protective services professionals are common and screening is highly variable. objectives: our objective was to measure the rates of occult abusive injuries detected in contacts of abused children using a common screening protocol. methods: this was a multi-center, observational cohort study of child abuse teams who shared a common screening protocol. data were collected between jan , and april , for all children < years undergoing evaluation for physical abuse and their contacts. for contacts of abused children, the protocol recommended physical examination for all children < years, skeletal survey and physical exam for children < months, and physical exam, skeletal survey, and neuroimaging for children < months old. results: among , children evaluated for abuse, met criteria as ''physically abused'' and these had contacts. for each screening modality, screening was completed as recommended by the protocol in approximately % of cases. of contacts who met criteria for skeletal survey, new injuries were identified in ( . %). none of these fractures had associated findings on physical examination. physical examination identified new injuries in . % of eligible contacts. neuroimaging failed to identify new injuries among eligible contacts less than months old. twins were at significantly increased risk of fracture relative to other nontwin contacts (or . ). conclusion: these results support routine skeletal survey for contacts of physically abused children < months old, regardless of physical examination findings. even for children where no injuries are identified, these results demonstrate that abuse is common among children who share a home with an abused child, and support including contacts in interventions (foster care, safety planning, social support) designed to protect physically abused children. methods: this was a retrospective study evaluating all children presenting to eight paediatric, universityaffiliated eds during one year in - . in each setting, information regarding triage and disposition were prospectively registered by clerks in the ed database. anonymized data were retrieved from the ed computerized database of each participating centre. in the absence of a gold standard for triage, hospitalisation, admission to intensive care unit (icu), length of stay in the ed, and proportion of patients who left without being seen by a physician (lwbs) were used as surrogate markers of severity. the primary outcome measure was the association between triage level (from to ) and hospitalisation. the association between triage level and dichotomous outcomes was evaluated by a chi-square test, while a student's t-test was used to evaluate the association between triage level and length of stay. it was estimated that the evaluation of all children visiting these eds for a one year period would provide a minimum of , patients in each triage level and at least events for outcomes having a proportion of % or more. results: a total of , children visited the eight eds during the study period. pooled data demonstrated hospitalisation proportions of %, %, %, %, and . % for patients triaged at level , , , , and respectively (p < . ). there was also a strong association between triage levels and admission to icu (p < . ), the proportion of children who lwbs (p < . ), and length of stay (p < . ). background: parents frequently leave the emergency department (ed) with incomplete understanding of the diagnosis and plan, but the relationship between comprehension and post-care outcomes has not been well described. objectives: to explore the relationship between comprehension and post-discharge medication safety. methods: we completed a planned secondary analysis of a prospective observational study of the ed discharge process for children aged - months. after discharge, parents completed a structured interview to assess comprehension of the child's condition, the medical team's advice, and the risk of medication error. limited understanding was defined as a score of - from (excellent) to (poor). risk of medication error was defined as a plan to use over-the-counter cough/cold medication and/or an incorrect dose of acetaminophen (measured by direct observation at discharge or reported dose at follow-up call). parents identified as at risk received further instructions from their provider. the primary outcome was persistent risk of medication error assessed at phone interview - days post-discharge. a major barrier to administering analgesics to children is the perceived discomfort of intravenous access. the delivery of intranasal analgesia may be a novel solution to this problem. objectives: we investigated whether the addition of the mucosal atomizer device (mad) as an alternative for fentanyl delivery would improve overall fentanyl administration rates in pediatric patients transported by a large urban ems system. we performed a historical control trial comparing the rate of pediatric fentanyl administration months before and months after the introduction of the mad. study subjects were pediatric trauma patients (age < years) transported by a large urban ems agency. the control group was composed of patients treated in the months before introduction of the mad. the experimental group included patients treated in the months after the addition of the mad. two physicians reviewed each chart and determined whether the patient met predetermined criteria for the administration of pain medication. a third reviewer resolved any discrepancies. fentanyl administration rates were measured and compared between the two groups. we used two-sample t-tests and chi-square tests to analyze our data. results: patients were included in the study: patients in the pre-mad group and in the post-mad group. there were no significant differences in the demographic and clinical characteristics of the two groups. ( . %) patients in the control arm received fentanyl. ( . %) of patients in the experimental arm received fentanyl with % of the patients receiving fentanyl via the intranasal route. the addition of the mad was not associated with a statistically significant increase in analgesic administration. age and mechanism of injury were statistically more predictive of analgesia administration. conclusion: while the addition of the mucosal atomizer device as an alternative delivery method for fentanyl shows a trend towards increased analgesic administration in a prehospital pediatric population, age and mechanism of injury are more predictive in who receives analgesia. further research is necessary to investigate the effect of the mad on pediatric analgesic delivery. methods: this was a prospective study evaluating php-se before (pre) and after (post) a ppp introduction and months later ( -mo). php groups received either ppp review and education or ppp review alone. the ppp included a pain assessment tool. the se tool, developed and piloted by pediatric ems experts, uses a ranked ordinal scale ranging from 'certain i cannot do it' ( ) to 'completely certain i can do it' ( ) for items: pain assessment ( items), medication administration ( ) and dosing ( ) , and reassessment ( ). all items and an averaged composite were evaluated for three age groups (adult, child, toddler). paired sample t-tests compared post-and -mo scores to pre-ppp scores. results: of phps who completed initial surveys, phps completed -mo surveys. ( %) received education and ppp review and ( %) review only. ppp education did not affect php-se (adult p = . , child p = . , toddler p = . ). the largest se increase was in pain assessment. this increase persisted for child and toddler groups at months. the immediate increase in composite se scores for all age groups persisted for the toddler group at months. conclusion: increases in composite and pain assessment php-se occur for all age groups immediately after ppp introduction. the increase in pain assessment se persisted at months for pediatric age groups. composite se increase persisted for the toddler age group alone. background: pediatric medications administered in the prehospital setting are given infrequently and dosage may be prone to error. calculation of dose based on known weight or with use of length-based tapes occurs even less frequently and may present a challenge in terms of proper dosing. objectives: to characterize dosing errors based on weight-based calculations in pediatric patients in two similar emergency medical service (ems) systems. methods: we studied the five most commonly administered medications given to pediatric patients weighing kg or less. drugs studied were morphine, midazolam, epinephrine : , , epinephrine : , and diphenhydramine. cases from the electronic record were studied for a total of months, from january to july . each drug was administered via intravenous, intramuscular, or intranasal routes. drugs that were permitted to be titrated were excluded. an error was defined as greater than % above or below the recommended mg/kg dosage. results: out of , total patients, , were pediatric patients. had documented weights of < kg and patients were given these medications. we excluded patients for weight above the %ile or below the %ile, or if the weight documentation was missing. of the patients and doses, errors were noted in ( %; % ci %, %). midazolam was the most common drug in errors ( of doses or %; % ci %, %), followed by diphenhydramine ( / or %; % ci %, %), epinephrine ( / or %; % ci %, %), and morphine sulfate ( / or %; % ci, %, %). underdosing was noted in of ( %; % ci %, %) of errors, while excessive dosing was noted in of ( %; % ci %, %). conclusion: weight-based dosing errors in pediatric patients are common. while the clinical consequences of drug dosing errors in these patients are unknown, a considerable amount of inaccuracy occurs. strategies beyond provision of reference materials are needed to prevent pediatric medication errors and reduce the potential for adverse outcomes. drivers background: homelessness affects up to . million people a year. the homeless present more frequently to eds, their ed visits are four times more likely to occur within days of a prior ed evaluation, and they are admitted up to five times more frequently than others. we evaluated the effect of a street outreach rapid response team (sorrt) on the health care utilization of a homeless population. a nonmedical outreach staff responds to the ed and intensely case manages the patient: arranges primary care follow-up, social services, temporary housing opportunities, and drug/ alcohol rehabilitation services. objectives: we hypothesized that this program would decrease the ed visits and hospital admissions of this cohort of patients. methods: before and after study at an urban teaching hospital from june, -december, in indianapolis, indiana. upon identification of homeless status, sorrt was immediately notified. eligibility for sorrt enrollment is determined by housing and urban development homeless criteria and the outreach staff attempted to enter all such identified patients into the program. the patients' health care utilization was evaluated in the months prior to program entry as compared to the months after enrollment by prospectively collecting data and a retrospective medical record query for any unreported visits. since the data were highly skewed, we used the nonparametric signed rank test to test for paired differences between periods. results: patients met criteria but two refused participation. the -patient cohort had total ed visits ( pre and post) with a mean of . (sd . ) and median of . (range - ) ed visits in months pre-sorrt as compared to a mean of . (sd . ) and median of . ( - ) in months post-sorrt (p = . ). there were total inpatient admissions pre-intervention and post-intervention, with a mean of . (sd . ) and median of . ( . ) per patient in the pre-intervention period as compared to . (sd . ) and . ( - ) in the post-intervention period (p = . ). in the pre-sorrt period . % had at least one inpatient admission as compared to . % post-sorrt (p = . ). there were no differences in icu days or overall length of stay between the two periods. conclusion: an aggressive case management program beginning immediately with homeless status recognition in the ed has not demonstrated success in decreasing utilization in our population. methods: this was a secondary analysis of a prospective randomized trial that included consenting patients discharged with outpatient antibiotics from an urban county ed with an annual census of , . patients unable to receive text messages or voice-mails were excluded. health literacy was assessed using a validated health literacy assessment, the newest vital sign (nvs). patients were randomized to a discharge instruction modality: ) standard care, typed and verbal medication and case-specific instructions; ) standard care plus text-messaged instructions sent to the patient's cell phone; or ) standard care plus voice-mailed instructions sent to the patient's cell. patients were called at days to determine preference for instruction delivery modality. preference for discharge instruction modality was analyzed using z-tests for proportions. results: patients were included ( % female, median age , range months to years); were excluded. % had an nvs score of - , % - , and % - . among the . % of participants reached at days, % preferred a modality other than written. there was a difference in the proportion of patients who preferred discharge instructions in written plus another modality (see table) . with the exception of written plus another modality, patient preference was similar across all nvs score groups. conclusion: in this sample of urban ed patients, more than one in four patients prefer non-traditional (text message, voice-mail) modalities of discharge instruction delivery to standard care (written) modality alone. additional research is needed to evaluate the effect of instructional modality on accessibility and patient compliance. figure) . conclusion: cumulative saps ii scoring fails to predict mortality in ohca. the risk scores assigned to age, gcs, and hco independently predict mortality and combined are good mortality predictors. these findings suggest that an alternative severity of illness score should be used in post-cardiac arrest patients. future studies should determine optimal risk scores of saps ii variables in a larger cohort of ohca. objectives: to determine the extent to which cpp recovers to pre-pause levels with seconds of cpr after a -second interruption in chest compressions for ecg rhythm analysis. methods: this was a secondary analysis of prospectively collected data from an iacuc-approved protocol. fortytwo yorkshire swine (weighing - kg) were instrumented under anesthesia. vf was electrically induced. after minutes of untreated vf, cpr was initiated and a standard dose of epinephrine (sde) ( . mg/kg) was given. after . minutes of cpr to circulate the vasopressor, compressions were interrupted for seconds to analyze the ecg rhythm. this was immediately followed by seconds of cpr to restore cpp before the first rs was delivered. if the rs failed, cpr resumed and additional vasopressors (sde, and vasopressin . mg/kg) were given and the sequence repeated. the cpp was defined as aortic diastolic pressure minus right atrial diastolic pressure. the cpp values were extracted at three time points: immediately after the . minutes of cpr, following the -second pause, and immediately before defibrillation for the first two rs attempts in each animal. eighty-three sets of measurements were logged from animals. descriptive statistics were used to analyze the data. in most cities, the proportion of patients who achieve prehospital return of spontaneous circulation (rosc) is less than %. the association between time of day and ohca outcomes in the prehospital setting is unknown. objectives: we sought to determine whether rates of prehospital rosc varied by time of day. we hypothesized that night ohcas would exhibit lower rates of rosc. methods: we performed a retrospective review of cardiac arrest data from a large, urban ems system. included were all ohcas occurring in individuals > years of age from / / to / / . excluded were traumatic arrests and cases where resuscitation measures were not performed. day was defined as : am- : pm, while night was : pm- : am. we examined the association between time of day and paramedic-perceived prehospital rosc in unadjusted and adjusted analyses. variables included age, sex, race, presenting rhythm, aed application by a bystander or first responder, defibrillation, and bystander cpr performance. analyses were performed using chisquare tests and logistic regression. objectives: determine whether a smei helps to improve physician compliance with ihi bundle and reduce patient mortality in ed patients with s&s. methods: we conducted a pre-smei retrospective review of four months of ed patients with s&s to determine baseline pre-smei physician compliance and patient mortality. we designed and completed a smei attended by of ed attending physicians and of ed resuscitation residents. finally, we conducted a twenty-month post-smei prospective study of ongoing physician compliance and patient mortality in ed patients with s&s. results: in the four month pre-smei retrospective review, we identified patients with s&s, with a % physician overall compliance and mortality rate of %. the average ed physician smei multiple-choice pre-test score was %, and showed a significant improvement in the post-test score of % (p = . ). additionally, % of ed physicians were able to describe three new clinical pearls learned and % agreed that the smei would improve compliance. in the twenty months of the post-smei prospective study, we identified patients with s&s, with a % physician overall compliance, and mortality rate of %. relative physician compliance improved % (p = . ) and relative patient mortality was reduced by % (p < . ) when comparing pre-and post-smei data. conclusion: our data suggest that a smei improves overall physician compliance with the six hour goals of the ihi bundle and reduces patient mortality in ed patients with s&s. conclusion: using a population-level, longitudinal, and multi-state analysis, the rate of return visits within days is higher than previously reported, with nearly in returning back to the ed. we also provide the first estimation of health care costs for ed revisits. background: the ability of patients to accurately determine their level of urgency is important in planning strategies that divert away from eds. in fact, an understanding of patient self-triage abilities is needed to inform health policies targeting how and where patients access acute care services within the health care system. objectives: to determine the accuracy of a patient's self-assessment of urgency compared against triage nurses. methods: setting: ed patients are assigned a score by trained nurses according to the canadian emergency department triage and acuity scale (ctas). we present a cross-sectional survey of a random patient sample from urban/regional eds conducted during the winters of and . this previously validated questionnaire, based on the british healthcare commission survey, was distributed according to a modified dillman protocol. exclusion criteria consisted of: age - years, left prior to being seen/treated, died during ed visit, no contact information, presented with a privacy-sensitive case. alberta health services provided linked non-survey administrative data. results: , surveys distributed with a response rate of %. patients rated health problems as life-threatening ( %), possibly life-threatening ( %), urgent ( %), somewhat urgent ( %), or not urgent ( %). triage nurses assigned the same patients ctas scores of i (< %), ii ( %), iii ( %), iv ( %) or v ( %). patients self-rated their condition as or points less urgent than the assigned ctas score (< % of the time), points less urgent ( %), point less urgent ( %), exactly as urgent ( %), point more urgent ( %), points more urgent ( %), or or points more urgent ( %, respectively). among ctas i or ii patients, % described their problem as life-threatening/possibly life-threatening, % as urgent (risk of permanent damage), % as urgent (needed to be seen that day), and % as not urgent (wanted to be but did not need to be seen that day). conclusion: the majority of ed patients are generally able to accurately assess the acuity of their problem. encouraging patients with low-urgency conditions to self-triage to lower-acuity sources of care may relieve stress on eds. however, physicians and patients must be aware that a small minority of patients are unable to self-triage safely. when the tourniquet was released, blood spurted from the injured artery as hydrostatic pressure decayed. pressure and flow were recorded in three animals (see table) . the concept was proof-tested in a single fresh frozen human cadaver with perfusion through the femoral artery and hemorrhage from the popliteal artery. the results were qualitatively and quantitatively similar to the swine carcass model. conclusion: a perfused swine carcass can simulate exsanguinating hemorrhage for training purposes and serves as a prototype for a fresh-frozen human cadaver model. additional research and development are required before the model can be widely applied. background: in the pediatric emergency department (ped), clinicians must work together to provide safe and effective care. crisis resource management (crm) principles have been used to improve team performance in high-risk clinical settings, while simulation allows practice and feedback of these behaviors. objectives: to develop a multidisciplinary educational program in a ped using simulation-enhanced teamwork training to standardize communication and behaviors and identify latent safety threats. methods: over months a workgroup of physicians and nurses with experience in team training and simulation developed an educational program for clinical staff of a tertiary ped. goals included: create a didactic curriculum to teach the principles of crm, incorporate principles of crm into simulation-enhanced team training in-situ and center-based exercises, and utilize assessment instruments to evaluate for teamwork, completion of critical actions, and presence of latent safety threats during in-situ sim resuscitations. results: during phase i, clinicians, divided into teams, participated in -minute pre-training assessments of pals-based in-situ simulations. in phase ii, staff participated in a -hour curriculum reviewing key crm concepts, including team training exercises utilizing simulation and expert debriefing. in phase iii, staff participated in post-training minute teamwork and clinical skills assessments in the ped. in all phases, critical action checklists (cac) were tabulated by simulation educators. in-situ simulations were recorded for later review using the assessment tools. after each simulation, educators facilitated discussion of perceptions of teamwork and identification of systems issues and latent hazards. overall, in-situ simulations were conducted capturing % of the physicians and % of the nurses. cac data were collected by an observer and compared to video recordings. over significant systems issues, latent hazards, and knowledge deficits were identified. all components of the program were rated highly by % of the staff. conclusion: a workgroup of pem, simulation, and team training experts developed a multidisciplinary team training program that used in-situ and centerbased simulation and a refined crm curriculum. unique features of this program include its multidisciplinary focus, the development of a variety of assessment tools, and use of in-situ simulation for evaluation of systems issues and latent hazards. this program was tested in a ped and findings will be used to refine care and develop a sustainment program while addressing issues identified. objectives: our hypothesis is that participants trained on high-fidelity mannequins will perform better than participants trained on low-fidelity mannequins on both the acls written exam and in performance of critical actions during megacode testing. the study was performed in the context of an acls initial provider course for new pgy residents at the penn medicine clinical simulation center and involved three training arms: ) low fidelity (low-fi): torso-rhythm generator; ) mid-fidelity (mid-fi): laerdal simmanÒ turned off; and ) high-fidelity (high-fi): laerdal simmanÒ turned on. training in each arm of the study followed standard aha protocol. educational outcomes were evaluated by written scores on the acls written examination and expert rater reviews of acls megacode videos performed by trainees during the course. a sample of subjects were randomized to one of the three training arms: low-fi (n = ), mid-fi (n = ), or high-fi (n = ). results: statistical significance across the groups was determined using analysis-of-variance (anova). the three groups had similar written pre-test scores [low-fi . ( . ), mid-fi . ( . ), and high-fi . ( . )] and written post-test scores [low-fi . ( . ), mid-fi . ( . ), and high-fi . ( . )]. similarly, test improvement was not significantly different. after completion of the course, high-fi subjects were more likely to report they felt comfortable in their simulator environment (p = . ). low-fi subjects were less likely to perceive a benefit in acls training from high-fi technology (p < . ). acls instructors were not rated significantly different by the subjects using the debriefing assessment for simulation in healthcareª (dash) student version except for element , where the high-fi group subjects reported lower scores ( . vs . and . in the other groups, p = . ). objectives: we sought to determine if stress associated with the performance of a complex procedural task can be affected by level of medical training. heart rate variability (hrv) is used as a measure of autonomic balance, and therefore an indicator of the level of stress. methods: twenty-one medical students and emergency medicine residents were enrolled. participants performed airway procedures on an airway management trainer. hrv data were collected using a continuous heart rate variability monitoring system. participant hrv was monitored at baseline, during the unassisted first attempt at endotracheal intubation, during supervised practice, and then during a simulated respiratory failure clinical scenario. standard deviation of beat to beat variability (sdnn), very low frequency (vlf), total power (tp), and low frequency (lf) was analyzed to determine the effect of practice and level of training on the level of stress. a cohen's d test was used to determine differences between study groups. results: sdnn data showed that second-year residents were less stressed during all stages than were fourthyear medical students (avg d = . ). vlf data showed third-year residents exhibited less sympathetic activity than did first-year residents (avg d = ) . ). the opportunity to practice resulted in less stress for all participants. tp data showed that residents had a greater degree of control over their autonomic nervous system (ans) than did medical students (avg d = . ). lf data showed that subjects were more engaged in the task at hand as the level of training increased indicating autonomic balance (avg d = . ). conclusion: our hrv data show that stress associated with the performance of a complex procedural task is reduced by increased training. hrv may provide a quantitative measure of physiologic stress during the learning process and thus serve as a marker of when a subject is adequately trained to perform a particular task. objectives: we seek to examine whether intubation during cpr can be done as efficiently as intubation without ongoing cpr. the hypothesis is that the predictable movement of an automated chest compression device will make intubation easier than the random movement from manual cpr. methods: the project was an experimental controlled trial and took place in the emergency department at a tertiary referral center in peoria, illinois. emergency medicine residents, attendings, paramedics, and other acls trained staff were eligible for participation. in randomized order, each participant attempted intubation on a mannequin with no cpr ongoing, during cpr with a human compressor, and during cpr with an automatic chest compression device (physio control lucas ). participants could use whichever style laryngoscope they felt most comfortable with and they were timed during the three attempts. success was determined after each attempt. results: there were participants in the trial. the success rate in the control group and the automated cpr group were both % ( / ) and the success rate in the manual cpr group was % ( / ). the differences in success rates were not statistically significant (p = . and p = . ). the automated cpr group had the fastest average time ( . sec; p = . ). the mean times for intubation with manual cpr and no cpr were not statistically different ( . sec, . sec; p = . ). conclusion: the success rate of tracheal intubation with ongoing chest compression was the same as the success rate of intubation without cpr. although intubation with automatic chest compression was faster than during other scenarios, all methods were close to the second timeframe recommended by acls. based on these findings, it may not always be necessary to hold cpr to place a definitive airway; however, further studies will be needed. background: after acute myocardial infarction, vascular remodeling in the peri-infarct area is essential to provide adequate perfusion, prevent additional myocyte loss, and aid in the repair process. we have previously shown that endogenous fibroblast growth factor (fgf ) is essential to the recovery of contractile function and limitation of infarct size after cardiac ischemia-reperfusion (ir) injury. the role of fgf in vascular remodeling in this setting is currently unknown. objectives: determine the role of endogenous fgf in vascular remodeling in a clinically relevant, closed-chest model of acute myocardial infarction. methods: mice with a targeted ablation of the fgf gene (fgf knockout) and wild type controls were subjected to a closed-chest model of regional cardiac ir injury. in this model, mice were subjected to minutes of occlusion of the left anterior descending artery followed by reperfusion for either or days. immunofluorescence was performed on multiple histological sections from these hearts to visualize capillaries (endothelium, anti-cd antibody), larger vessels (venules and arterioles, antismooth muscle actin antibody), and nuclei (dapi). digital images were captured, and multiple images from each heart were measured for vessel density and vessel size. results: sham-treated fgf knockout and wild type mice show no differences in capillary or vessel density suggesting no defect in vessel formation in the absence of endogenous fgf . when subjected to closed-chest regional cardiac ir injury, fgf knockout hearts had normal capillary and vessel number and size in the peri-infarct area after day of reperfusion compared to wild type controls. however, after days, fgf knockout hearts showed significantly decreased capillary and vessel number and increased vessel size compared to wild type controls (p < . ). conclusion: these data show the necessity of endogenous fgf in vascular remodeling in the peri-infarct zone in a clinically relevant animal model of acute myocardial infarction. these findings may suggest a potential role for modulation of fgf signaling as a therapeutic intervention to optimize vascular remodeling in the repair process after myocardial infarction. the diagnosis of aortic dissections by ed physicians is rare scott m. alter, barnet eskin, john r. allegra morristown medical center, morristown, nj background: aortic dissection is a rare event. the most common symptom of dissection is chest pain, but chest pain is a frequent emergency department (ed) chief complaint and other diseases that cause chest pain, such as acute coronary syndrome and pulmonary embolism, occur much more frequently. furthermore, % of dissections are without chest pain and % are painless. for all these reasons, diagnosing dissection can be difficult for the ed physician. we wished to quantify the magnitude of this problem in a large ed database. objectives: our goal was to determine the number of patients diagnosed by ed physicians with aortic dissections compared to total ed patients and to the total number of patients with a chest pain diagnosis. methods: design: retrospective cohort. setting: suburban, urban, and rural new york and new jersey eds with annual visits between , and , . participants: consecutive patients seen by ed physicians from january , through december , . observations: we identified aortic dissections using icd- codes and chest pain diagnoses by examining all icd- codes used over the period of the study and selecting those with a non-traumatic chest pain diagnosis. we then calculated the number of total ed patients and chest pain patients for every aortic dissection diagnosed by emergency physicians. we determined % confidence intervals (cis). results: from a database of . million ed visits, we identified ( . %) aortic dissections, or one for every , ( % ci , to , ) visits. the mean age of aortic dissection patients was ± years and % were female. of the total visits there were , ( %) with a chest pain diagnosis. thus there is one aortic dissection diagnosis for every ( % ci to , ) chest pain diagnoses. conclusion: the diagnosis of aortic dissections by ed physicians is rare. an ed physician seeing , to , patients a year would diagnose an aortic dissection approximately once every to years. an aortic dissection would be diagnosed once for approximately every , ed chest pain patients. patients were excluded if they suffered a cardiac arrest, were transferred from another hospital, or if the ccl was activated for an inpatient or from ems in the field. fp ccl activation was defined as ) a patient for whom activation was cancelled in the ed and ruled out for mi or ) a patient who went to catheterization but no culprit vessel was identified and mi was excluded. ecgs for fp patients were classified using standard criteria. demographic data, cardiac biomarkers, and all relevant time intervals were collected according to an on-going quality assurance protocol. results: a total of ccl activations were reviewed, with % male, average age , and % black. there were ( %) true stemis and ( %) fp activations. there were no significant differences between the fp patients who did and did not have catheterization. for those fp patients who had a catheterization ( %), ''door to page'' and ''door to lab'' times were significantly longer than the stemi patients (see table) , but there was substantial overlap. there was no difference in sex or age, but fp patients were more likely to be black (p = . ). a total of fp patients had ecgs available for review; findings included anterior elevation with convex ( %) or concave ( %) elevation, st elevation from prior anterior ( %) or inferior ( %) mi, pericarditis ( %), presumed new lbbb ( %), early repolarization ( %), and other ( %). conclusion: false ccl activation occurred in a minority of patients, most of whom had ecg findings warranting emergent catheterization. the rate of false ccl activation appears acceptable. background: atrial fibrillation (af) is the most common cardiac arrhythmia treated in the ed, leading to high rates of hospitalization and resource utilization. dedicated atrial fibrillation clinics offer the possibility of reducing the admission burden for af patients presenting to the ed. while the referral base for these af clinics is growing, it is unclear to what extent these clinics contribute to reducing the number of ed visits and hospitalizations related to af. objectives: to compare the number of ed visits and hospitalizations among discharged ed patients with a primary diagnosis of af who followed up with an af clinic and those who did not. methods: a retrospective cohort study and medical records review including three major tertiary centres in calgary, canada. a sample of patients was taken representing patients referred to the af clinic from the calgary zone eds and compared to matched control ed patients who were referred to other providers for follow-up. the controls were matched for age and sex. inclusion criteria included patients over years of age, discharged during the index visit, and seen by the af clinic between january , and october , . exclusion criteria included non-residents and patients hospitalized during the index visit. the number of cardiovascular-related ed visits and hospitalizations was measured. all data are categorical, and were compared using chi-square tests. results: patients in the control and af clinic cohorts were similar for all baseline characteristics except for a higher proportion of first episode patients in the intervention arm. in the six months following the index ed visit, study group patients ( . %) visited an ed on occasions, and ( %) were hospitalized on occasions. of the control group, patients ( . %) visited an ed on occasions, and ( %) were hospitalized on occasions. using a chi-square test we found no significant difference in ed visits (p = . ) or hospitalizations (p = . ) between the control and af clinic cohorts. conclusion: based on our results, referral from the ed to an af clinic is not associated with a significant reduction in subsequent cardiovascular related ed visits and hospitalizations. due to the possibility of residual confounding, randomized trials should be performed to evaluate the efficacy of af clinics. reported an income of less than $ , . there were no significant associations between sex, race, marital status, education level, income, insurance status, and subsequent -and- day readmission rates. hla score was not found to be significantly related to readmission rates. the mean hla score was . (sd = . ), equivalent to less than th grade literacy, meaning these patients may not be able to read prescription labels. for each unit increase in hfkt score, the odds of being readmitted within days decreased by . (p < . ) and for - days decreased by . (p < . ). for each unit increase in scbs score, the odds of being readmitted within days decreased by . (p = . ). conclusion: health care literacy in our patient population is not associated with readmission, likely related to the low literacy rate of our study population. better hf knowledge and self-care behaviors are associated with lower readmission rates. greater emphasis should be placed on patient education and self-care behaviors regarding hf as a mechanism to decrease readmission rates. comparison of door to balloon times in patients presenting directly or transferred to a regional heart center with stemi jennifer ehlers, adam v. wurstle, luis gruberg, adam j. singer stony brook university, stony brook, ny background: based on the evidence, a door-to-balloon-time (dtbt) of less than minutes is recommended by the aha/acc for patients with stemi. in many regions, patients with stemi are transferred to a regional heart center for percutaneous coronary intervention (pci). objectives: we compared dtbt for patients presenting directly to a regional heart center with those for patients transferred from other regional hospitals. we hypothesized that dtbt would be significantly longer for transferred patients. methods: study design-retrospective medical record review. setting-academic ed at a regional heart center with an annual census of , that includes a catchment area of hospitals up to miles away. patients-patients with acute stemi identified on ed -lead ecg. measures-demographic and clinical data including time from triage to ecg, from ecg to activation of regional catheterization lab, and from initial triage to pci (dtbt , and door to intravascular balloon deployment (d b). methods: the study was performed in an inner-city academic ed between / / and / / . every patient for whom ed activation of our stemi system occurred was included. all times data from a pre-existing quality assurance database were collected prospectively. patient language was determined retrospectively by chart review. results: there were patients between / / and / / . patients ( %) were deemed too sick or unable to provide history and were excluded, leaving patients for analysis. ( %) spoke english and ( %) did not. in the non-english group, chinese was the most common language, in ( %) background: syncope is a common, potentially highrisk ed presentation. hospitalization for syncope, although common, is rarely of benefit. no populationbased study has examined disparities in regional admission practices for syncope care in the ed. moreover, there are no population-based studies reporting prognostic factors for -and -day readmission of syncope. objectives: ) to identify factors associated with admission as well as prognostic factors for -and -day readmission to these hospitals; ) to evaluate variability in syncope admission practices across different sizes and types of hospitals. methods: design -multi-center retrospective cohort study using ed administrative data from albertan eds. participants/subjects -patients > years of age with syncope (icd : r ) as a primary or secondary diagnosis from to june . readmission was defined as return visits to the ed or admission < days or - days after the index visit (including against medical advice and left without being seen during the index visit). outcomes -factors associated with hospital admission at index presentation, and readmission following ed discharge, adjusted using multivariable logistic regression. results: overall, syncope visits occurred over years. increased age, increased length of stay (los), performance of cxr, transport by ground ambulance, and treatment at a low-volume hospital (non-teaching or non-large urban) were independently associated with index hospitalization. these same factors, as well as hospital admission itself, were associated with -day readmission. additionally, increased age, increased los, performance of a head ct, treatment at a low-volume hospital, hospital admission, and female sex were independently associated with - day readmission. arrival by ground ambulance was associated with a decreased likelihood of both -and - day readmission. conclusion: our data identify variations in practice as well as factors associated with hospitalization and readmission for syncope. the disparity in admission and readmission rates between centers may highlight a gap in quality of care or reflect inappropriate use of resources. further research to compare patient out-comes and quality of patient care among urban and non-urban centers is needed. background: change in dyspnea severity (ds) is a frequently used outcome measure in trials of acute heart failure (ahf). however, there is limited information concerning its validity. objectives: to assess the predictive validity of change in dyspnea severity. methods: this was a secondary analysis of a prospective observational study of a convenience sample of ahf patients presenting with dyspnea to the ed of an academic tertiary referral center with a mixed urban/ suburban catchment area. patients were enrolled weekdays, june through december . patients assessed their ds using a -cm visual analog scale at three times: the start of ed treatment (baseline) as well as at and hours after starting ed treatment. the difference between baseline and hour was the -hour ds change. the difference between baseline and hours was the -hour ds change. two clinical outcome measures were obtained: ) the number of days hospitalized or dead within days of the index visit ( -day outcome), and ) the number of days hospitalized or dead within days of the index visit ( -day outcome). results: data on patients were analyzed. the median -day outcome variable was days with an interquartile range (iqr) of to . the median -day outcome variable was days (iqr to . ). the median -hour ds change was . cm (iqr . to . ). the median -hour ds change was . cm (iqr . to . ). the -day and -day mortality rates were % and % respectively. the spearman rank correlations and % confidence intervals are presented in the table below. conclusion: while the point estimates for the correlations were below . , the % ci for two of the correlations extended above . . these pilot data support change in ds as a valid outcome measure for ahf when measured over hours. a larger prospective study is needed to obtain a more accurate point estimate of the correlations. background: the majority of volume-quality research has focused on surgical outcomes in the inpatient setting; very few studies have examined the effect of emergency department (ed) case volume on patient outcomes. objectives: to determine whether ed case volume of acute heart failure (ahf) is associated with short-term patient outcomes. methods: we analyzed the nationwide emergency department sample (neds) and nationwide inpatient sample (nis), the largest, all-payer, ed and inpatient databases in the us. ed visits for ahf were identified with a principal diagnosis of icd- -cm code .xx. eds were categorized into quartiles by ed case volume of ahf. the outcome measures were early inpatient mortality (within the first days of admission), overall inpatient mortality, and hospital length of stay (los). results: there were an estimated , visits for ahf from approximately , eds in ; % were hospitalized. of these, the overall inpatient mortality rate was . %, and the median hospital los was days. early inpatient mortality was lower in the highest-volume eds, compared with the lowest-volume eds ( . % vs. . %; p < . ). similar patterns were observed for overall inpatient mortality ( . % vs. . %; p < . ). in a multivariable analysis adjusting for patient and hospital characteristics, early inpatient mortality remained lower in patients admitted through the highest-volume eds (adjusted odds ratios [or], . ; % confidence interval [ci], . - . ), as compared with the lowest-volume eds. there was a trend towards lower overall inpatient mortality in the highest-volume eds; however, this was not statistically significant (adjusted or, . ; %ci, . - . ). by contrast, using the nis data including various sources of admissions, a higher case volume of inpatient ahf patients predicted lower overall inpatient mortality (adjusted or, . ; %ci, . - . ). the hospital los in patients admitted through the highest-volume eds was slightly longer (adjusted difference, . day; %ci, . - . ), compared with the lowest-volume eds. conclusion: ed patients who are hospitalized for ahf have an approximately % reduced early inpatient mortality if they were admitted from an ed that handles a large volume of ahf cases. the ''practice-makesperfect'' concept may hold in emergency management of ahf. emergency department disposition and charges for heart failure: regional variability alan b. storrow, cathy a. jenkins, sean p. collins, karen p. miller, candace mcnaughton, naftilan allen, benjamin s. heavrin vanderbilt university, nashville, tn background: high inpatient admission rates for ed patients with acute heart failure are felt partially responsible for the large economic burden of this most costly cardiovascular problem. objectives: we examined regional variability in ed disposition decisions and regional variability in total dollars spent on ed services for admitted patients with primary heart failure. methods: the nationwide emergency department sample (neds) was used to perform a retrospective, cohort analysis of patients with heart failure (icd- code of .x) listed as the primary ed diagnosis. demographics and disposition percentages (with se) were calculated for the overall sample and by region: northeast, south, midwest, and west. to account for the sample design and to obtain national and regional estimates, a weighted analysis was conducted. results: there were , weighted ed visits with heart failure listed as the primary diagnosis. overall, over eighty percent were admitted (see table) . fifty-two percent of these patients were female; mean age was . years (se . ). hospitalization rates were higher in the northeast ( . %) and south ( . %) than in the midwest ( . %) and west ( . %). total monies spent on ed services were highest in the south ($ , , ) followed by the northeast ($ , , ), west ($ , , ) and midwest ($ , , ) . conclusion: this large retrospective ed cohort suggests a very high national admission rate with significant regional variation in both disposition decisions as well as total monies spent on ed services for patients with a primary diagnosis of heart failure. examining these estimates and variations further may provide strategies to reduce the economic burden of heart failure. background: workplace violence in health care settings is a frequent occurrence. gunfire in hospitals is of particular concern. however, information regarding such workplace violence is limited. accordingly, we characterized u.s. hospital-based shootings from - . objectives: to determine extent of hospital-based shootings in the u.s. and involvement of emergency departments. methods: using lexisnexis, google, netscape, pub-med, and sciencedirect, we searched reports for acute care hospital shooting events from january through december , and those with at least one injured victim were analyzed. results: we identified hospital-related shootings ( inside the hospital, on hospital grounds), in states, with victims, of whom were perpetrators. in comparison to external shootings, shootings within the hospital have not increased over time (see figure) . perpetrators were from all age groups, including the elderly. most of the events involved a determined shooter: grudge ( %), suicide ( %), ''euthanizing'' an ill relative ( %), and prisoner escape ( %). ambient societal violence ( %) and mentally unstable patients ( %) were comparatively infrequent. the most common injured was the perpetrator ( %). hospital employees comprised only % of victims; physician ( %) and nurse ( %) victims were relatively infrequent. the emergency department was the most common site ( %), followed by patient rooms ( %) and the parking lot ( %). in % of shootings within hospitals, the weapon was a security officer's gun grabbed by the perpetrator. ''grudge'' motive was the only factor determinative of hospital staff victims (or = . , % ci . - . ). conclusion: although hospital-based shootings are relatively rare, emergency departments are the most likely site. the unpredictable nature of this type of event represents a significant challenge to hospital security and deterrence practices, as most perpetrators proved determined, and many hospital shootings occur outside the building. impact of emergency physician board certification on patient perceptions of ed care quality albert g. sledge iv , carl a. germann , tania d. strout , john southall maine medical center, portland, me; mercy hospital, portland, me background: the hospital value-based purchasing program mandated by the affordable care act is the latest example of how patients' perceptions of care will affect the future practice environment of all physicians. the type of training of medical providers in the emergency department (ed) is one possible factor affecting patient perceptions of care. a unique situation in a maine community ed led to the rapid transition from non-emergency medicine (em) residency trained physicians to all em residency trained and american board of emergency medicine (abem) certified providers. objectives: the purpose of this study was to evaluate the effect of the implementation of an all em-trained, abem-certified physician staff on patient perceptions of the quality of care they received in the ed. methods: we retrospectively evaluated press ganey data from surveys returned by patients receiving treatment in a single, rural ed. survey items addressed patient's perceptions of physician courtesy, time spent listening, concern for patient comfort, and informativeness. additional items evaluated overall perceptions of care and the likelihood that the respondent would recommend the ed to another. data were compared for the three years prior to and following implementation of the all trained, certified staff. we used the independent samples t-test to compare mean responses during the two time periods. bonferroni's correction was applied to adjust for multiple comparisons. results: during the study period, , patients provided surveys for analysis: , during the pre-certification phase and , during the post-certification phase. across all six survey items, mean responses increased following transition to the board-certified staff. these improvements were noted to be statistically significant in each case: courtesy p < . , time listening p < . , concern for comfort p < . , informativeness p < . , overall perception of care p < . , and likelihood to recommend p < . . conclusion: data from this community ed suggest that transition from a non-residency trained, abem certified staff to a fully trained and certified model has important implications for patient's perceptions of the care they receive. we observed significant improvement in rating scores provided by patients across all physicianoriented and general ed measures. background: transfer of care from the ed to the inpatient floor is a critical transition when miscommunication places patients at risk. the optimal form and content of handoff between providers has not been defined. in july , ed-to-floor signout for all admissions to the medicine and cardiology floors was changed at our urban, academic, tertiary care hospital. previously, signout was via an unstructured telephone conversation between ed resident and admitting housestaff. the new signout utilizes a web-based ed patient tracking system and includes: ) a templated description of ed course is completed by the ed resident; ) when a bed is assigned, an automated page is sent to the admitting housestaff; ) ed clinical information, including imaging, labs, medications, and nursing interventions (figure) is reviewed by admitting housestaff; ) if housestaff has specific questions about ed care, a telephone conversation between the ed resident and housestaff occurs; ) if there are no specific questions, it is indicated electronically and the patient is transferred to the floor. objectives: to describe the effects on patient safety (floor-to-icu transfer in hours) and ed throughput (ed length of stay (los) and time from bed assignment to ed departure) resulting from a change to an electronic, discussion-optional handoff system. conclusion: transition to a system in which signout of admitted patients is accomplished by accepting housestaff review of ed clinical information supplemented by verbal discussion when needed resulted in no significant change in rate of floor-to-icu transfer or ed los and reduced time from bed assignment to ed departure. background: emergency physicians may be biased against patients presenting with nonspecific complaints or those requiring more extensive work-ups. this may result in patients being seen less quickly than those with more straightforward presentations, despite equal triage scores or potential for more dangerous conditions. objectives: the goal of our study was to ascertain which patients, if any, were seen more quickly in the ed based on chief complaint. methods: a retrospective report was generated from the emr for all moderate acuity (esi ) adult patients who visited the ed from january through december at a large urban teaching hospital. the most common complaints were: abdominal pain, alcohol intoxication, back pain, chest pain, cough, dyspnea, dizziness, fall, fever, flank pain, headache, infection, pain (nonspecific), psychiatric evaluation, ''sent by md,'' vaginal bleeding, vomiting, and weakness. non-parametric independent sample tests assessed median time to be seen (ttbs) by a physician for each complaint. differences in the ttbs between genders and based on age were also calculated. chi-square testing compared percentages of patients in the ed per hour to assess for differences in the distribution of arrival times. results: we obtained data from , patients. patients with a chief complaint of weakness and dizziness waited the longest with a median time of minutes and patients with flank pain waited the shortest with minutes (p < . ) ( figure ). overall, males waited minutes and females waited minutes (p < . ). stratifying by gender and age, younger females between the ages of - waited significantly longer times when presenting with a chief complaint of abdominal pain (p < . ), chest pain (p < . ), or flank pain (p < . ) as compared to males in the same age group ( figure ). there was no difference in the distribution of arrival times for these complaints. conclusion: while the absolute time differences are not large, there is a significant bias toward seeing young male patients more quickly than women or older males despite the lower likelihood of dangerous conditions. triage systems should perhaps take age and gender better into account. patients might benefit from efforts to educate em physicians on the delays and potential quality issues associated with this bias in an attempt to move toward more egalitarian patient selection. background: detailed analysis of emergency department (ed) event data identified the time from completion of emergency physician evaluation (doc done) to the time patients leave the ed as a significant contributor to ed length of stay (los) and boarding at our institution. process flow mapping identified the time from doc done to the time inpatient beds were ordered (bo) as an interval amendable to specific process improvements. objectives: the purpose of this study was to evaluate the effect of ed holding orders for stable adult . ( . - . ) . ( . - . ) . ( . - . ) . ( . - . ) . ( . - . ) . ( . - . ) inpatient medicine (aim) patients on: a) the time to bo and b) ed los. methods: a prospective, observational design was used to evaluate the study questions. data regarding the time to bo and los outcomes were collected before and after implementation of the ed holding orders program. the intervention targeted stable aim patients being admitted to hospitalist, internal medicine, and family medicine services. ed holding orders were placed following the admission discussion with the accepting service and special attention was paid to proper bed type, completion of the emergent work-up and the expected immediate course of the patient's hospital stay. holding orders were of limited duration and expired hours after arrival to the inpatient unit. results: during the -month study period, patients were eligible for the ed holding orders intervention; ( . %) were cared for using the standard adult medicine order set and ( . %) received the intervention. the median time from doc done to bo was significantly shorter for patients in the ed holding orders group, min (iqr , ) vs. min (iqr , ) for the standard adult medicine group, p < . . similarly, the median ed los was significantly shorter for those in the ed holding orders group, min (iqr , ) vs. min (iqr , ) for the standard adult medicine group, p < . . no lapses in patient care were reported in the intervention group. conclusion: in this cohort of ed patients being admitted to an aim service, placing ed holding orders rather than waiting for a traditional inpatient team evaluation and set of admission orders significantly reduced the time from the completion of the ed workup to placement of a bo. as a result, ed los was also significantly shortened. while overall utilization of the intervention was low, it improved with each month. emergency department interruptions in the age of electronic health records matthew albrecht, john shabosky, jonathan de la cruz southern illinois university school of medicine, springfield, il background: interruptions of clinical care in the emergency department (ed) have been correlated with increased medical errors and decreased patient satisfaction. studies have also shown that most interruptions happen during physician documentation. with the advent of the electronic health record and computerized documentation, ed physicians now spend much of their clinical time in front of computers and are more susceptible to interruptions. voice recognition dictation adjuncts to computerized charting boast increased provider efficiency; however, little is known about how data input of computerized documentation affects physician interruptions. objectives: we present here observational interruptions data comparing two separate ed sites, one that uses computerized charting by conventional techniques and one assisted by voice recognition dictation technology. methods: a prospective observational quality initiative was conducted at two teaching hospital eds located less than mile from each other. one site primarily uses conventional computerized charting while the other uses voice recognition dictation computerized charting. four trained observers followed ed physicians for minutes during shifts. the tasks each ed physician performed were noted and logged in second intervals. tasks listed were selected from a predetermined standardized list presented at observer training. tasks were also noted as either completed or placed in queue after a change in task occurred. a total of minutes were logged. interruptions were noted when a change in task occurred with the previous task being placed in queue. data were then compared between sites. results: ed physicians averaged . interruptions/ hour with conventional computerized charting compared to . interruptions/hour with assisted voice recognition dictation (p = . ). conclusion: computerized charting assisted with voice recognition dictation significantly decreased total per hour interruptions when compared to conventional techniques. charting with voice recognition dictation has the potential to decrease interruptions in the ed allowing for more efficient workflow and improved patient care. background: using robot assistants in health care is an emerging strategy to improve efficiency and quality of care while optimizing the use of human work hours. robot prototypes capable of performing vital signs and assisting with ed triage are under development. however, ed users' attitudes toward robot assistants are not well studied. understanding of these attitudes is essential to design user-friendly robots and to prepare eds for the implementation of robot assistants. objectives: to evaluate the attitudes of ed patients and their accompanying family and friends toward the potential use of robot assistants in the ed. methods: we surveyed a convenience sample of adult ed patients and their accompanying adult family members and friends at a single, university-affiliated ed, / / - / / . the survey consisted of eight items from the negative attitudes towards robots scale (normura et al.) modified to address robot use in the ed. response options included a -point likert scale. a summary score was calculated by summing the responses for all items, with a potential range of (completely negative attitude) to (completely positive attitude). research assistants gave the written surveys to subjects during their ed visit. internal consistency was assessed using cronbach's alpha. bivariate analyses were performed to evaluate the association between the summary score and the following variables: participant type (patient or visitor), sex, race, time of day, and day of week. results: of potential subjects approached, ( %) completed the survey. participants were % patients, % family members or friends, % women, % white, and had a median age of . years (iqr - ). cronbach's alpha was . . the mean summary score was . (sd = . ), indicating subjects were between ''occasionally'' and ''sometimes'' comfortable with the idea of ed robot assistants (see table) . men were more positive toward robot use than women (summary score: . vs . ; p = . ). no differences in the summary score were detected based on participant type, race, time of day, or day of week. conclusion: ed users reported significant apprehension about the potential use of robot assistants in the ed. future research is needed to explore how robot designs and strategies to implement ed robots can help alleviate this apprehension. background: emergency department cardioversion (edc) of recent-onset atrial fibrillation or flutter (af) patients is an increasingly common management approach to this arrhythmia. patients who qualify for edc generally have few co-morbidities and are often discharged directly from the ed. this results in a shift towards a sicker population of patients admitted to the hospital with this diagnosis. objectives: to determine whether hospital charges and length of stay (los) profiles are affected by emergency department discharge of af patients. methods: patients receiving treatment at an urban teaching community hospital with a primary diagnosis of atrial fibrillation or flutter were identified through the hospital's billing data base. information collected on each patient included date of service, patient status, length of stay, and total charges. patient status was categorized as inpatient (admitted to the hospital), observation (transferred from the ed to an inpatient bed but placed in an observation status), or ed (discharged directly from the ed). the hospital billing system automatically defaults to a length of stay of for observation patients. ed patients were assigned a length of stay of . total hospital charges and mean los were determined for two different models: a standard model (sm) in which patients discharged from the ed were excluded from hospital statistics, and an inclusive model (im) in which discharged ed patients were included in the hospital statistics. statistical analysis was through anova. results: a total of patients were evaluated for af over an -month period. of these, ( %) were admitted, ( %) were placed in observation status, and ( %) were discharged from the ed. hospital charges and los in days are summarized in the table. all differences were statistically significant at (p < . ). conclusion: emergency department management can lead to a population of af patients discharged directly from the ed. exclusion of these patients from hospital statistics skews performance profiles effectively punishing institutions for progressive care. background: recent health care reform has placed an emphasis on the electronic health record (ehr). with the advent of the ehr it is common to see ed providers spending more time in front of computers documenting and away from patients. finding strategies to decrease provider interaction with computers and increase time with patients may lead to improved patient outcomes and satisfaction. computerized charting adjuncts, such as voice recognition software, have been marketed as ways to improve provider efficiency and patient contact. objectives: we present here observational data comparing two separate ed sites, one where computerized charting is done by conventional techniques and one that is assisted with voice recognition dictation, and their effects on physican charting and patient contact. methods: a prospective observational quality initiative was conducted at two teaching hospitals located less than mile from each other. one site primarily uses conventional computerized charting while the other uses voice recognition dictation. four trained quality assistants observed ed physicians for minutes during shifts. the tasks each physician performed were noted and logged in second intervals. tasks listed were identified from a predetermined standardized list presented at observer training. a total of minutes were logged. time allocated to charting and that allocated to direct patient care were then compared between sites. results: ed physicians spent . % of their time charting using conventional techniques vs . % using voice recognition dictation (p = . ). time allocated to direct patient care was found to be . % with conventional charting vs . % using dictation (p = ). in total, ed physicians using conventional charting techniques spent / minutes charting. ed physicians using voice recognition dictation spent / minutes dictating and an additional . / minutes reviewing or correcting their dictations. the use of voice recognition assisted dictation rather than conventional techniques did not significantly change the amount of time physicians spent charting or with direct patient care. although voice recognition dictation decreased initial input time of documenting data, a considerable amount of time was required to review and correct these dictations. objectives: for our primary objective, we studied whether emergency department triage temperatures detected fever adequately when compared to a rectal temperature. as secondary objectives, we examined the temperature differences when a rectal temperature was taken within an hour of non-invasive temperature, temperature site (oral, axillary, temporal), and also examined the patients that were initially afebrile but were found to be febrile by rectal temperature. methods: we performed an electronic chart review at our inner city, academic emergency department with an annual census of , patients. we identified all patients over the age of who received a non-invasive triage temperature and a subsequent rectal temperature while in the ed from january through february . specific data elements included many aspects of the patient's medical record (e.g. subject demographics, temperature, and source). we analyzed our data with standard descriptive statistics, t-tests for continuous variables, and pearson chi-square tests for proportions. results: a total of , patients met our inclusion criteria. the mean difference in temperatures between the initial temperature and the rectal temperature was . °f, with . % having higher rectal temperatures ‡ °f, and . % having higher rectal temperatures ‡ °f. the mean temperature difference among the , patients who an initial noninvasive temperature and a rectal temperature within one hour was . °f. the mean difference among patients that received oral, axillary, and temporal temperatures was . °f, . °f, and . °f respectively. approximately one in five patients ( . %) were initially afebrile and found to be febrile by rectal temperature, with an average temperature difference of . °f. these patients had a higher rate of admission, and were more likely to be admitted to the intensive care unit. conclusion: there are significant differences between rectal temperatures and non-invasive triage temperatures in this emergency department cohort. in almost one in five patients, fever was missed by triage temperature. background: pediatric emergency department (ped) overcrowding has become a national crisis, and has resulted in delays in treatment, and patients leaving without being seen. increased wait times have also been associated with decreased patient satisfaction. optimizing ped throughput is one means by which to handle the increased demands for services. various strategies have been proposed to increase efficiency and reduce length of stay (los). objectives: to measure the effect of direct bedding, bedside registration, and patient pooling on ped wait times, length of stay, and patient satisfaction. methods: data were extracted from a computerized ed tracking system in an urban tertiary care ped. comparisons were made between metrics for ( , patients) and the months following process change ( , patients). during , patients were triaged by one or two nurses, registered, and then sent either to a -bed ped or a physically separate -bed fast-track unit, where they were seen by a physician. following process change, patients were brought directly to a bed in the -bed ped, triaged and registered, then seen by a physician. the fast-track unit was only utilized to accommodate patient surges. results: anticipating improved efficiencies, attending physician coverage was decreased by %. after instituting process changes, improvements were noted immediately. although daily patient volume increased by %, median time to be seen by a physician decreased by %. additionally, median los for discharged patients decreased by %, and median time until the decisionto-admit decreased by %. press-ganey satisfaction scores during this time increased by greater than mean score points, which was reported to be a statistically significant increase. conclusion: direct bedding, bedside registration, and patient pooling were simple to implement process changes. these changes resulted in more efficient ped throughput, as evidenced by decreased times to be seen by a physician, los for discharged patients, and time until decision-to-admit. additionally, patient satisfaction scores improved, despite decreased attending physician coverage and a % decrease in room utilization. ) . during period , the ou was managed by the internal medicine department and staffed by primary care physicians and physician assistants. during periods and , the ou was managed and staffed by em physicians. data collected included ou patient volume, length of stay (los) for discharged and admitted patients, admission rates, and -day readmission rates for discharged patients. cost data collected included direct, indirect, and total cost per patient encounter. data were compared using chi-square and anova analysis followed by multiple pairwise comparisons using the bonferroni method of p-value adjustment. results: see table. the ou patient volume and percent of ed volume was greater in period compared to periods and . length of stay, admission rates, -day readmission rates, and costs were greater in period compared to periods and . conclusion: em physicians provide more cost-effective care for patients in this large ou compared to non-em physicians, resulting in shorter los for admitted and discharged patients, greater rates of patients discharged, and less -day readmission rates for discharged patients. this is not affected by an increase in ou volume and shows a trend towards improvement. background: emergency department (ed) crowding continues to be a problem, and new intake models may represent part of the solution. however, little data exist on the sustainability and long-term effects of physician triage and screening on standard ed performance metrics, as most studies are short-term. objectives: we examined the hypothesis that a physician screening program (start) sustainably improves standard ed performance metrics including patient length of stay (los) and patients who left without completing assessment (lwca). we also investigated the number of patients treated and dispositioned by start without using a monitored bed and the median patient door-to-room time. methods: design and setting: this study is a retrospective before-and-after analysis of start in a level i tertiary care urban academic medical center with approximately , annual patient visits. all adult patients from december until november are included, though only a subset was seen in start. start began at our institution in december . observations: our outcome measures were length of stay for ed patients, lwca rates, patients treated and dispositioned by start without using a monitored bed, and door-to-room time. statistics: simple descriptive statistics were used. p-values for los were calculated with wilcoxon test and p-value for lwca was calculated with chi-square. results: table shows median length of stay for ed patients was reduced by minutes/patient (p-value < . ) when comparing the most recent year to the year before start. patients who lwca were reduced from . % to . % (p-value < . ) during the same time period. we also found that in the first half-year of start, % of patients screened in the ed were treated and dispositioned without using a monitored bed and by the end of year , this number had grown to %. median door-to-room time decreased from . minutes to . minutes over the same period of time. conclusion: a start system can provide sustained improvements in ed performance metrics, including a significant reduction in ed los, lwca rate, and doorto-room time. additionally, start can decrease the need for monitored ed beds and thus increase ed capacity. . labs were obtained in %, ct in %, us in %, and consultation in %. % of the cohort was admitted to the hospital. the most commonly utilized source of translation was a layman ( %). a professional translator was used in % and translation service (language line, marty) in %. the examiner was fluent in the patient's language in %. both the patient and examiner were able to maintain basic communication in %. there were patients in the professional/ fluent translation group and patients in the lay translation group. there was no difference in ed los between groups vs min; p = . . there was no difference in the frequency of lab tests, computerized tomography, ultrasound, consultations, or hospital admission. frequencies did not differ by sex or age. conclusion: translation method was not associated with a difference in overall ed los, ancillary test use, or specialist consultation in spanish-speaking patients presenting to the ed for abdominal pain. emergency department patients on warfarin -how often is the visit due to the medication? jim killeen, edward castillo, theodore chan, gary vilke ucsd medical center, san diego, ca background: warfarin has important therapeutic value for many patients, but has been associated with signi-ficant bleeding complications, hypersensitivity reactions, and drug-drug interactions, which can result in patients seeking care in the emergency department (ed). objectives: to determine how often ed patients on warfarin present for care as a result of the medication itself. methods: a multi-center prospective survey study in two academic eds over months. patients who presented to the ed taking warfarin were identified, and ed providers were prospectively queried at the time of disposition regarding whether the visit was the result of a complication or side effect associated with warfarin. data were also collected on patient demographics, chief complaint, triage acuity, vital signs, disposition, ed evaluation time, and length of stay (los). patients identified with a warfarin-related cause for their ed visit were compared with those who were not. statistical analysis was performed using descriptive statistics. results: during the study period, , patients were cared for by ed staff, of whom were identified as taking warfarin as part of their medication regimen. of these, providers identified . % ( patients) who presented with a warfarin-related complication as their primary reason for the ed visit. . % ( ) each hours of daily boarding is associated with a drop of . raw score points in both pg metrics. these seemingly small drops in raw scores translate into major changes in rankings on press ganey national percentile scales (a difference of as much as percentile points). our institution commonly has hundreds of hours of daily boarding. it is possible that patient-level measurements of boarding impact would show stronger correlation with individual satisfaction scores, as opposed to the daily aggregate measures we describe here. our research suggests that reducing the burden of boarding on eds will improve patient satisfaction. background: prolonged emergency department (ed) boarding is a key contributor to ed crowding. the effect of output interventions (moving boarders out of the ed into an intermediate area prior to admission or adding additional capacity to an observation unit) has not been well studied. objectives: we studied the effect of a combined observation-transition (ot) unit, consisting of observation beds and an interim holding area for boarding ed patients, on the length of stay (los) for admitted patients, as well as secondary outcomes such as los for discharged patients, and left without being seen rates. methods: we conducted a retrospective review ( months pre-, months post-design) of an ot unit at an urban teaching ed with , annual visits (study ed). we compared outcomes to a nearby communitybased ed with , annual visits in the same health system (control ed) where no capacity interventions were performed. the ot had beds, full monitoring capacity, and was staffed hours per day. the number of beds allocated to transition and observation patients fluctuated throughout the course of the intervention, based on patient demands. all analyses were conducted at the level of the ed-day. wilcoxon rank-sum and analysis of covariance tests were used for comparisons; continuous variables were summarized with medians. results: in unadjusted analyses, median daily los of admitted patients at the study ed was minutes lower in the months after the ot opened, . to . hours (p < . ). control site daily los for admitted patients increased minutes from . to . hours (p < . ). results were similar after adjusting for other covariates (day of week, ed volume, and triage level). los of discharged patients at study ed decreased by minutes, from . hours to . hours (p < . ), while the control ed saw no significant changes in discharged patient los ( . hours to . hours, p = . ). left without being seen rates did not decrease at either site. conclusion: opening an ot unit was associated with a -minute reduction in average daily ed los for admitted patients and discharged patients in the study ed. given the large expense of opening an ot, future studies should compare capacity-dependent (e.g., ot) vs. capacity-independent (e.g, organizational) interventions to reduce ed crowding. fran balamuth, katie hayes, cynthia mollen, monika goyal children's hospital of philadelphia, philadelphia, pa background: lower abdominal pain and genitourinary problems are common chief complaints in adolescent females presenting to emergency departments. pelvic inflammatory disease (pid) is a potentially severe complication of lower genital tract infections, which involves inflammation of the female upper genital tract secondary to ascending stis. pid has been associated with severe sequelae including infertility, ectopic pregnancy, and chronic pelvic pain. we describe the prevalence and microbial patterns of pid in a cohort of adolescent females presenting to an urban emergency department with abdominal or genitourinary complaints. objectives: to describe the prevalence and microbial patterns of pid in a cohort of adolescent patients presenting to an ed with lower abdominal or genitourinary complaints. methods: this is a secondary analysis of a prospective study of females ages - years presenting to a pediatric ed with lower abdominal or genitourinary complaints. diagnosis of pid was per cdc guidelines. patients underwent chlamydia trachomatis (ct) and neisseria gonorrhea (gc) testing via urine aptima combo assay and trichomonas vaginalis (tv) testing using the vaginal osom trichomonas rapid test. descriptive statistics were performed using stata . . results: the prevalence of pid in this cohort of patients was . % ( % ci . %, . %), . % ( % ci . %, . %) of whom had positive sexually transmitted infection (sti) testing: % ( % ci . %, . %) with ct, . % ( % ci . , . %) with gc, and . % ( % ci . %, . %) with tv. . % ( % ci . , . %) of patients diagnosed with pid received antibiotics consistent with cdc recommendations. patients with lower abdominal pain as their chief complaint were more likely to have pid than patients with genitourinary complaints (or . , % ci . , . ). conclusion: a substantial number of adolescent females presenting to the emergency department with lower abdominal pain were diagnosed with pid, with microbial patterns similar to those previously reported in largely adult, outpatient samples. furthermore, appropriate treatment for pid was observed in the majority of patients diagnosed with pid. impact background: in resource-poor settings, maternal health care facilities are often underutilized, contributing to high maternal mortality. the effect of ultrasound in these settings on patients, health care providers, and communities is poorly understood. objectives: the purpose of this study was to assess the effect of the introduction of maternal ultrasound in a population not previously exposed to this intervention. methods: an ngo-led program trained nurses at four remote clinics outside koutiala, mali, who performed , maternal ultrasound scans over three years. our researchers conducted an independent assessment of this program, which involved log book review, sonographer skill assessment, referral follow-up, semi-structured interviews of clinic staff and patients, and focus groups of community members in surrounding villages. analyses included the effect of ultrasound on clinic function, job satisfaction, community utilization of prenatal care and maternity services, alterations in clinical decision making, sonographer skill, and referral frequency. we used qrs nvivo to organize qualitative findings, code data, and identify emergent themes, and graphpad software (la jolla, ca) and microsoft excel to tabulate quantitative findings results: -findings that triggered changes in clinical practice were noted in . % of ultrasounds, with a . % referral rate to comprehensive maternity care facilities. -skill retention and job satisfaction for ultrasound providers was high. -the number of patients coming for antenatal care increased, after introduction of ultrasound, in an area where the birth rate has been decreasing. -over time, women traveled from farther distances to access ultrasound and participate in antenatal care. -very high acceptance among staff, patients and community members. -ultrasound was perceived as most useful for finding fetal position, sex, due date, and well-being. -improved confidence in diagnosis and treatment plan for all cohorts. -improved compliance with referral recommendations. -no evidence of gender selection motivation for ultrasound use. conclusion: use of maternal ultrasound in rural and resource-limited settings draws women to an initial antenatal care visit, increases referral, and improves job satisfaction among health care workers. methods: a retrospective database analysis was conducted using the electronic medical record from a single, large academic hospital. ed patients who received a billing diagnosis of ''nausea and vomiting of pregnancy'' or ''hyperemesis gravidarum'' between / / and / / were selected. a manual chart review was conducted with demographic and treatment variables collected. statistical significance was determined using multiple regression analysis for a primary outcome of return visit to the emergency department for nausea and vomiting of pregnancy. results: patients were identified. the mean age was . years (sd± . ), mean gravidity . (sd± . ), and mean gestational age . weeks (sd± . ). the average length of ed evaluation was min (sd± ). of the patients, ( . %) had a return ed visit for nausea and vomiting of pregnancy, ( %) were admitted to the hospital, and ( %) were admitted to the ed observation protocol. multiple regression analysis showed that the presence of medical co-morbidity (p = . ), patient gravditity (p = . ), gestational age (p = . ), and admission to the hospital (p = . ) had small but significant effects on the primary outcome (return visits to the emergency department). no other variables were found to be predictive of return visits to the ed including admission to the ed observation unit or factors classically thought to be associated with severe forms of nausea and vomiting in pregnancy including ketonuria, electrolyte abnormalities, or vital sign abnormalities. conclusion: nausea and vomiting in pregnancy has a high rate of return ed visits that can be predicted by young patient age, low patient gravidity, early gestational age, and the presence of other comorbidities. these patients may benefit from obstetric consultation and/or optimization of symptom management after discharge in order to prevent recurrent utilization of the ed. prevalence conclusion: there is a high prevalence of ht in adult sa victims. although our study design and data do not allow us to make any inferences regarding causation, this first report of ht ed prevalence suggests the opportunity to clarify this relationship and the potential opportunity to intervene. background: sexually transmitted infections (sti) are a significant public health problem. because of the risks associated with stis including pid, ectopic pregnancy, and infertility the cdc recommends aggressive treatment with antibiotics in any patient with a suspected sti. objectives: to determine the rates of positive gonorrhea and chlamydia (g/c) screening and rates of empiric antibiotic use among patients of an urban academic ed with > , visits in boston, ma. methods: a retrospective study of all patients who had g/c cultures in the ed over months. chi-square was used in data analysis. sensitivity and specificity were also calculated. results: a positive rate of / ( . %) was seen for gonorrhea and / ( . %) for chlamydia. females had positive rates of / ( . %) and / ( . %) respectively. males had higher rates of / ( . %) (p =< . ) and / ( . %) (p = . ). patients with g/c sent received an alternative diagnosis, the most common being uti ( ), ovarian pathology ( ), vaginal bleeding ( ), and vaginal candidiasis ( ); were excluded. this left without definitive diagnosis. of these, . % ( / ) of females were treated empirically with antibiotics for g/c, and a greater percentage of males ( %, / ) were treated empirically (p < . ). of those empirically treated, / ( . %) had negative cultures. meanwhile / ( . %) who ultimately had positive cultures were not treated with antibiotics during their ed stay. sensitivity of the provider to predict presence of disease based on decision to give empiric antibiotics was . (ci . - . ). specificity was . (ci . - . ). conclusion: most patients screened in our ed for g/c did not have positive cultures and . % of those treated empirically were found not to have g/c. while early treatment is important to prevent complications, there are risks associated with antibiotic use such as allergic reaction, c difficile infection, and development of antibiotic resistance. our results suggest that at our institution we may be over-treating for g/c. furthermore, despite high rates of treatment, % of patients who ultimately had positive cultures did not receive antibiotics during their ed stay. further research into predictive factors or development of a clinical decision rule may be useful to help determine which patients are best treated empirically with antibiotics for presumed g/c. background: air travel may be associated with unmeasured neurophysiological changes in an injured brain that may affect post-concussion recovery. no study has compared the effect of commercial airtravel on concussion injuries despite rather obvious decreased oxygen tension and increased dehydration effect on acute mtbi. objectives: to determine if air travel within - hours of concussion is associated with increased recovery time in professional football and hockey players. methods: prospective cohort study of all active-roster national football league and national hockey league players during the - seasons. internet website review of league sties for injury identification of concussive injury and when player returned to play solely for mtbi. team schedules and flight times were also confirmed to include only players who flew immediately following game (within - hr). multiple injuries were excluded as were players who had injury around all-star break for nhl and scheduled off week in nfl. results: during the - nfl and nhl seasons, ( . %) and ( . %) players experienced a concussion (percent of total players), in the respective leagues. of these, nfl players ( %) and nhl players ( %) flew within hours of the incident injury. the mean distance flown was shorter for nfl ( miles, sd vs. nhl , sd ) miles and all were in a pressurized cabin. the mean number of games missed for nfl and nhl players who traveled by air immediately after concussion was increased by % and % (respectively) than for those who did not travel by air nfl: . (sd . ) vs. . games (sd . ) and nhl: . games (sd . ) vs. . (sd . ); p < . . conclusion: this is an initial report of an increased rate of recovery in terms of more games missed, for professional athletes flying commercial airlines post-mtbi compared to those that do not subject their recently injured brains to pressurized airflight. the obvious changes of decreased oxygen tension with altitude equivalent of , feet, decreased humidity with increased dehydration, and duress of travel accompanying pressurized airline cabins all likely increase the concussion penumbra in acute mtbi. early air travel post concussion should be further evaluated and likely postponed - hr. until initial symptoms subside. background: previous studies have shown better in-hospital stroke time targets for those who arrive by ambulance compared to other modes of transport. however, regional studies report that less than half of stroke patients arrive by ambulance. objectives: our objectives were to describe the proportion of stroke patients who arrive by ambulance nationwide, and to examine regional differences and factors associated with the mode of transport to the emergency department (ed). methods: this is a cross-sectional study of all patients with a primary discharge diagnosis of stroke based on previously validated icd- codes abstracted from the national hospital ambulatory medical care survey for - . we excluded subjects < years of age and those with missing data. the study related survey variables included patient demographics, community characteristics, mode of transport to the hospital, and hospital characteristics. results: patients met inclusion criteria, representing , , patient records nationally. of these, . % arrived by ambulance. after adjustment for potential confounders, patients residing in the west and south had lower odds of arriving by ambulance for stroke when compared to northeast (southern region, or . , % ci . - . , western region, or . , % ci . - . , midwest region, or . , % ci . - . ). compared to the medicare population, privately insured and self insured had lower odds of arriving by ambulance (or for private insurance . , % ci . - . and or for self payers . , % ci . - . ). age, sex, race, urban or rural location of ed, or safety net status were not independently associated with ambulance use. conclusion: patients with stroke arrive by ambulance more frequently in the northeast than in other regions of the us. identifying reasons for this regional difference may be useful in improving ambulance utilization and overall stroke care nationwide. objectives: we sought to determine whether there was a difference in type of stroke presentation based upon race. we further sought to determine whether there is an increase in hemorrhagic strokes among asian patients with limited english proficiency. methods: we performed a retrospective chart review of all stroke patients age and older for year of patients that were diagnosed with cerebral vascular accident (cva) or intracranial hemorrhage (ich). we collected data on patient demographics, and past medical history. we then stratified patients according to race (white, black, latino, asian, and other). we classified strokes as ischemic, intracranial hemorrhage (ich), subarachnoid hemorrhage (sah), subdural hemorrhage (sdh), and other (e.g., bleeding into metatstatic lesions). we used only the index visit. we present the data percentages, medians and interquartile ranges (iqr). we tested the association of the outcome of intracranial hemorrhage against demographic and clinical variables using chi-square and kruskal-wallis tests. we performed a logistic regression model to determine factors related to presentation with an intracranial hemorrhage (ich background: the practice of obtaining laboratory studies and routine ct scan of the brain on every child with a seizure has been called into question in the patient who is alert, interactive, and back to functional baseline. there is still no standard practice for the management of non-febrile seizure patients in the pediatric emergency department (ped). objectives: we sought to determine the proportion of patients in whom clinically significant laboratory studies and ct scans of the brain were obtained in children who presented to the ped with a first or recurrent non-febrile seizure. we hypothesize that the majority of these children do not have clinically significant laboratory or imaging studies. if clinically significant values were found, the history given would warrant further laboratory and imaging assessment despite seizure alone. methods: we performed a retrospective chart review of patients with first-time or recurrent non-febrile seizures at an urban, academic ped between july to june . exclusion criteria included children who presented to the ped with a fever and age less than months. we looked at specific values that included a complete blood count, basic metabolic panel, and liver function tests, and if the child was on antiepileptics along with a level for a known seizure disorder, and ct scan. abnormal laboratory and ct scan findings were classified as clinically significant or not. results: the median age of our study population is years with male to female ratio of . . % of patients had a generalized tonic-clonic seizure. laboratory studies and ct scans were obtained in % and % of patients, respectively. five patients had clinically significant abnormal labs; however, one had esrd, one developed urosepsis, one had eclampsia, and two others had hyponatremia, which was secondary to diluted formula and trileptal toxicity. three children had an abnormal head ct: two had a vp shunt and one had a chromosomal abnormality with developmental delay. conclusion: the majority of the children analyzed did not have clinically significant laboratory or imaging studies in the setting of a first or recurrent non-febrile seizure. of those with clinically significant results, the patient's history suggested a possible etiology for their seizure presentation and further workup was indicated. background: in patients with a negative ct scan for suspected subarachnoid hemorrhage (sah), ct angiography (cta) has emerged as a controversial alternative diagnostic strategy in place of lumbar puncture (lp). objectives: to determine the diagnostic accuracy for sah and aneurysm of lp alone, cta alone, and lp followed by cta if the lp is positive. methods: we developed a decision and bayesian analysis to evaluate ) lp, ) cta, and ) lp followed by cta if the lp is positive. data were obtained from the literature. the model considers probability of sah ( %), aneurysm ( % if sah), sensitivity and specificity of ct ( . % and % overall), of lp (based on rbc and xanthochromia), and of cta, traumatic tap and its influence on sah detection. analyses considered all patients and those presenting at less than hours or greater than hours from symptom onset by varying the sensitivity and specificity of ct and cta. results: using the reported ranges of ct scan sensitivity and the specificity, the revised likelihood of sah following a negative ct ranged from . - . %, and the likelihood of aneurysm ranged from . - . %. following any of the diagnostic strategies, the likelihood of missing sah ranged from - . %. either lp strategy diagnosed . % of sahs versus - % with cta alone because cta only detected sah in the presence of an aneurysm. false positive sah with lp ranged from . - . % due to traumatic taps and with cta ranged from . - . % due to aneurysms without sah. the positive predictive value for sah ranged from . - % with lp and from . - % with cta. for patients presenting within hours of symptom onset, the revised likelihood of sah following a negative ct became . %, and the likelihood of aneurysm ranged from . - . %. following any of the diagnostic strategies, the likelihood of missing sah ranged from . - . %. either lp strategy diagnosed . % of sah versus - % with cta alone. false positive sah with lp was . % and with cta ranged from . - . %. the positive predictive value for sah was . % with lp and from . - % with cta. cta following a positive lp diagnosed . - % of aneurysms. conclusion: lp strategies are more sensitive for detecting sah but less specific than cta because of traumatic taps, leading to lower predictive value positives for sah with lp than with cta. either diagnostic strategy results in a low likelihood of missing sah, particularly within hours of symptom onset. background: recent studies support perfusion imaging as a prognostic tool in ischemic stroke, but little data exist regarding its utility in transient ischemic attack (tia). ct perfusion (ctp), which is more available and less costly to perform than mri, has not been well studied. objectives: to characterize ctp findings in tia patients, and identify imaging predictors of outcome. methods: this retrospective cohort study evaluated tia patients at a single ed over months, who had ctp at initial evaluation. a neurologist blinded to ctp findings collected demographic and clinical data. ctp images were analyzed by a neuroradiologist blinded to clinical information. ctp maps were described as qualitatively normal, increased, or decreased in mean transit time (mtt), cerebral blood volume (cbv), and cerebral blood flow (cbf). quantitative analysis involved measurements of average mtt (seconds), cbv (cc/ g) and cbf (cc/[ g x min]) in standardized regions of interest within each vascular distribution. these were compared with values in the other hemisphere for relative measures of mtt difference, cbv ratio, and cbffratio. mtt difference of ‡ seconds, rcbv as £ . , and rcbf as £ . were defined as abnormal based on prior studies. clinical outcomes including stroke, tia, or hospitalization during follow-up were determined up to one year following the index event. dichotomous variables were compared using fisher's exact test. logistic regression was used to evaluate the association of ctp abnormalities with outcome in tia patients. results: of patients with validated tia, had ctp done. mean age was ± years, % were women, and % were caucasian. mean abcd score was . ± . , and % had an abcd ‡ . prolonged mtt was the most common abnormality ( , %), and ( . %) had decreased cbv in the same distribution. on quantitative analysis, ( %) had a significant abnormality. four patients ( . %) had prolonged mtt and decreased cbv in the same territory, while ( %) had mismatched abnormalities. when tested in a multivariate model, no significant associations between mismatch abnormalities on ctp and new stroke, tia, or hospitalizations were observed. conclusion: ctp abnormalities are common in tia patients. although no association between these abnormalities and clinical outcomes was observed in this small study, this needs to be studied further. objectives: we hypothesized that pre-thrombolytic anti-hypertensive treatment (aht) may prolong door to treatment time (dtt). methods: secondary data analysis of consecutive tpatreated patients at randomly selected michigan community hospitals in the instinct trial. dtt among stroke patients who received pre-thrombolytic aht were compared to those who did not receive pre-thrombolytic aht. we then calculated a propensity score for the probability of receiving pre-thrombolytic aht using a logistic regression model with covariates including demographics, stroke risk factors, antiplatelet or beta blocker as home medication, stroke severity (nihss), onset to door time, admission glucose, pretreatment systolic and diastolic blood pressure, ems usage, and location at time of stroke. a paired t-test was then performed to compare the dtt between the propensity-matched groups. a separate generalized estimating equations (gee) approach was also used to estimate the differences between patients receiving pre-thrombolytic aht and those who did not while accounting for within-hospital clustering. results: a total of patients were included in instinct; however, onset, arrival, or treatment times were not able to be determined in , leaving patients for this analysis. the unmatched cohort consisted of stroke patients who received pre-thrombolytic aht and stroke patients who did not receive aht from - (table) . in the unmatched cohort, patients who received pre-thrombolytic aht had a longer dtt (mean increase minutes; % confidence interval (ci) - minutes) than patients who did not receive pre-thrombolytic aht. after propensity matching (table) , patients who received pre-thrombolytic aht had a longer dtt (mean increase . minutes, % ci . - . ) than patients who did not receive pre-thrombolytic aht. this effect persisted and its magnitude was not altered by accounting for clustering within hospitals. conclusion: pre-thrombolytic aht is associated with modest delays in dtt. this represents a feasible target for physician educational interventions and quality improvement initiatives. further research evaluating optimum hypertension management pre-thrombolytic treatment is warranted. post-pds, % had only pre-pds, and % had both. the most common pds included failure to treat post-treatment hypertension ( , %), antiplatelet agent within hours of treatment ( , %), pre-treatment blood pressure over / ( , %), anticoagulant agent within hours of treatment ( , %), and treatment outside the time window ( , %). symptomatic intracranial hemorrhage (sich) was observed in . % of patients with pds and . % of patients without any pd. in-hospital case fatality was % with and % without a pd. in the fully adjusted model, older age was significantly associated with pre-pds (table) . when post-pds were evaluated with adjustment for pre-pds, age was not associated with pds; however, pre-pds were associated with post-pds. conclusion: older age was associated with increased odds of pre-pds in michigan community hospitals. pre-pds were associated with post-pds. sich and in-hospital case fatality were not associated with pds; however, the low number of such events limited our ability to detect a difference. ct background: mri has become the gold standard for the detection of cerebral ischemia and is a component of multiple imaging enhanced clinical risk prediction rules for the short-term risk of stroke in patients with transient ischemic attack (tia). however, it is not always available in the emergency department (ed) and is often contraindicated. leukoaraiosis (la) is a radiographic term for white matter ischemic changes, and has recently been shown to be independently predictive of disabling stroke. although it is easily detected by both ct and mri, their comparative ability is unknown. objectives: we sought to determine whether leukoaraiosis, when combined with evidence of acute or old infarction as detected by ct, achieved similar sensitivity to mri in patients presenting to the ed with tia. methods: we conducted a retrospective review of consecutive patients diagnosed with tia between june and july that underwent both ct and mri as part of routine care within calendar day of presentation to a single, academic ed. ct and mr images were reviewed by a single emergency physician who was blinded to the mr images at the time of ct interpretation. la was graded using the van sweiten scale (vss), a validated grading scale applicable to both ct and mri. anterior and posterior regions were graded independently from to . results: patients were diagnosed with tia during the study period. of these, had both ct and mri background: helping others is often a rewarding experience but can also come with a ''cost of caring'' also known as compassion fatigue (cf). cf can be defined as the emotional and physical toll suffered by those helping others in distress. it is affected by three major components: compassion satisfaction (cs), burnout (bo), and traumatic experiences (te). previous literature has recognized an increase in bo related to work hours and stress among resident physicians. objectives: to assess the state of cf among residents with regard to differences in specialty training, hours worked, number of overnights, and demands of child care. we aim to measure associations with the three components of cf (cs, bo, and te). methods: we used the previously validated survey, proqol . the survey was sent to the residents after approval from the irb and the program directors. results: a total of responses were received ( % of the surveyed). five were excluded due to incomplete questionnaires. we found that residents who worked more hours per week had significantly higher bo levels (median vs , p = . ) and higher te ( vs , p = . ) than those working less hours. there was no difference in cs ( vs , p = . ). eighteen percent of the residents worked a majority of the night shifts. these residents had higher levels of bo background: emergency department (ed) billing includes both facility and professional fees. an algorithm derived from the medical provider's chart generates the latter fee. many private hospitals encourage appropriate documentation by financially incentivizing providers. academic hospitals sometimes lag in this initiative, possibly resulting in less than optimal charting. past attempts to teach proper documentation using our electronic medical record (emr) were difficult in our urban, academic ed of providers (approximately attending physicians, residents, and physician assistants). objectives: we created a tutorial to teach documentation of ed charts, modified the emr to encourage appropriate documentation, and provided feedback from the coding department. this was combined with an incentive structure shared equally amongst all attendings based on increased collections. we hypothesized this instructional intervention would lead to more appropriate billing, improve chart content, decrease medical liability, and increase educational value of charting process. methods: documentation recommendations, divided into two-month phases of - proposals, were administered to all ed providers by e-mails, lectures, and reminders during sign-out rounds. charts were reviewed by coders who provided individual feedback if specific phase recommendations were not followed. our endpoints included change in total rvu, rvus/ patient, e/m level distribution, and subjective quality of chart improvement. we did not examine effects on procedure codes or facility fees. results: our base average rvu/patient in our ed from / / - / / was . with monthly variability of approximately %. implementation of phase one increased average rvu/patient within two weeks to . ( . % increase from baseline, p < . ). the second aggregate phase implemented weeks later increased average rvu/patient to . ( . % increase from baseline, p < . ). conclusion: using our teaching methods, chart reviews focused on - recommendations at a time, and emr adjustments, we were able to better reflect the complexity of care that we deliver every day in our medical charts. future phases will focus on appropriate documentation for procedures, critical care, fast track, and pediatric patients, as well as examining correlations between increase in rvus with charge capture. identifying mentoring ''best practices'' for medical school faculty julie l. welch, teresita bellido, cherri d. hobgood background: mentoring has been identified as an essential component for career success and satisfaction in academic medicine. many institutions and departments struggle with providing both basic and transformative mentoring for their faculty. objectives: we sought to identify and understand the essential practices of successful mentoring programs. methods: multidisciplinary institutional stakeholders in the school of medicine including tenured professors, deans, and faculty acknowledged as successful mentors were identified and participated in focused interviews between mar-nov . the major area of inquiry involved their experiences with mentoring relationships, practices, and structure within the school, department, or division. focused interview data were transcribed and grounded theory analysis was performed. additional data collected by a institutional mentoring taskforce were examined. key elements and themes were identified and organized for final review. results: results identified the mentoring practices for three categories: ) general themes for all faculty, ) specific practices for faculty groups: basic science researchers, clinician researchers, clinician educators, and ) national examples. additional mentoring strategies that failed were identified. the general themes were quite universal among faculty groups. these included: clarify the best type of mentoring for the mentee, allow the mentee to choose the mentor, establish a panel of mentors with complementary skills, schedule regular meetings, establish a clear mentoring plan with expectations and goals, offer training and resources for both the mentor and mentee at institutional and departmental levels, ensure ongoing mentoring evaluation, create a mechanism to identify and reward mentoring. national practice examples offered critical recommendations to address multi-generational attitudes and faculty diversity in terms of gender, race, and culture. conclusion: mentoring strategies can be identified to serve a diverse faculty in academic medicine. interventions to improve mentoring practices should be targeted at the level of the institution, department, and individual faculty members. it is imperative to adopt results such as these to design effective mentoring programs to enhance the success of emergency medicine faculty seeking robust academic careers. background: women comprise half of the talent pool from which the specialty of emergency medicine draws future leaders, researchers, and educators and yet only % of full professors in us emergency medicine are female. both research and interventions are aimed at reducing the gender gap, however, it will take decades for the benefits to be realized which creates a methodological challenge in assessing system's change. current techniques to measure disparities are insensitive to systems change as they are limited to percentages and trends over time. objectives: to determine if the use of relative rate index (rri) better predicts which stage in the system women are not advancing in the academic pipeline than traditional metrics. methods: rri is a method of analysis that assesses the percent of sub-populations in each stage relative to their representation in the stage directly prior. thus, there is a better notion of the advancement given the availability to advance. rri also standardizes data for ease of interpretation. this study was conducted on the total population of academic professors in all departments at yale school of medicine during the academic year of - . data were obtained from the yale university provost's office. results: n = . there were a total of full, associate, and assistant professors. males comprised %, %, and % respectively. rri for the department of emergency medicine (dem) is . , . , and . , for full, associate, and assistant professors, respectively while the percentages were %, %, and % respectively. conclusion: relying solely on percentages masks improvements to the system. women are most represented at the associate professor level in dem, highlighting the importance of systems change evidence. specifically, twice as many women are promoted to associate professor rank given the number who exists as assistant professors. within years, the dem should have an equal system as the numbers of associate professors have dramatically increased and will be eligible to promote to full professor. additionally, dem has a better record of retaining and promoting women than other yale departments of medicine at both associate and full professor ranks. objectives: we examine the payer mixes of community non-rehabilitation eds in metropolitan areas by region to identify the proportion of academic and nonacademic eds that could be considered safety net eds. we hypothesize that the proportion of safety net academic eds is greater than that for non-academic eds and is increasing over time. methods: this is an ecological study examining us ed visits from through . data were obtained from the nationwide emergency department sample (neds). we grouped each ed visit according to the unique hospital-based ed identifier, thus creating a payer mix for each ed. we define a ''safety net ed'' as any ed where the payer mix satisfied any one of the following three conditions: ) > % of all ed visits are medicaid patients; ) > % of all ed visits are self-pay patients; or ) > % of all ed visits are either medicaid or self-pay patients. neds tags each ed with a hospital-based variable to delineate metropolitan/non-metropolitan locations and academic affiliation. we chose to examine a subpopulation of eds tagged as either academic metropolitan or non-academic metropolitan, because the teaching status of non-metropolitan hospitals was not provided. we then measured the proportion of eds that met safety net criteria by academic status and region. results: we examined , , , , and , weighted metro eds in years - , respectively. table presents safety net proportions. the proportions of academic safety net eds increased across the study period. widespread regional variability in safety net proportions existed across all years. the proportions of safety net eds were highest in the south and lowest in the northeast and midwest. table describes these findings for . conclusion: these data suggest that the proportion of safety-net academic eds may be greater than that of non-academic eds, is increasing over time, and is objectives: to examine the effect of ma health reform implementation on ed and hospital utilization before and after health reform, using an approach that relies on differential changes in insurance rates across different areas of the state in order to make causal inferences as to the effect of health reform on ed visits and hospitalizations. our hypothesis was that health care reform (i.e. reducing rates of uninsurance) would result in increased rates of ed use and hospitalizations. methods: we used a novel difference-in-differences approach, with geographic variation (at the zip code level) in the percentage uninsured as our method of identifying changes resulting from health reform, to determine the specific effect of massachusetts' health care reform on ed utilization and hospitalizations. using administrative data available from the massachusetts division of health care finance and policy acute hospital case mix databases, we compared a one-year period before health reform with an identical period after reform. we fit linear regression models at the area-quarter level to estimate the effect of health reform and the changing uninsurance rate (defined as self-pay only) on ed visits and hospitalizations. results: there were , , ed visits and , hospitalizations pre-reform and , , ed visits and , hospitalizations post-reform. the rate of uninsurance decreased from . % to . % in the ed group and from . % to . % in the hospitalization group. a reduction in the rate of the uninsured was associated with a small but statistically significant increase in ed utilization (p = . ) and no change in hospitalizations (p = . ). conclusion: we find that increasing levels of insurance coverage in massachusetts were associated with small but statistically significant increases in ed visits, but no differences in rates of hospitalizations. these results should aid in planning for anticipated changes that might result from the implementation of health reform nationally. with high levels of co-morbidity when untreated in adolescents. despite broad cdc screening recommendations, many youth do not receive testing when indicated. the pediatric emergency department (ped) is a venue with a high volume of patients potentially in need of sti testing, but assessing risk in the ped is difficult given constraints on time and privacy. we hypothesized that patients visiting a ped would find an audio-enhanced computer-assisted self-interview (acasi) program to establish sti risk easy to use, and would report a preference for the acasi over other methods of disclosing this information. objectives: to assess acceptability, ease of use, and comfort level of an acasi designed to assess adolescents' risk for stis in the ped. methods: we developed a branch-logic questionnaire and acasi system to determine whether patients aged - visiting the ped need sti testing, regardless of chief complaint. we obtained consent from participants and guardians. patients completed the acasi in private on a laptop. they read a one-page computer introduction describing study details and completed the acasi. patients rated use of the acasi upon completion using five-point likert scales. results: eligible patients visited the ped during the study period. we approached ( %) and enrolled and analyzed data for / ( %). the median time to read the introduction and complete the acasi was . minutes (interquartile range . - . minutes). . % of patients rated the acasi ''very easy'' or ''easy'' to use, . % rated the wording as ''very easy'' or ''easy'' to understand, % rated the acasi ''very short'' or ''short'', . % rated the audio as ''very helpful'' or ''helpful,'' . % were ''very comfortable'' or ''comfortable'' with the system confidentiality, and . % said they would prefer a computer interface over in-person interviews or written surveys for collection of this type of information. conclusion: patients rated the computer interface of the acasi as easy and comfortable to use. a median of . minutes was needed to obtain meaningful clinical information. the acasi is a promising approach to enhance the collection of sensitive information in the ped. the participants were randomized to one of three conditions, bi delivered by a computer (cbi), bi delivered by a therapist assisted by a computer (tbi), or control, and completed , , and month follow-up. in addition to content on alcohol misuse and peer violence, adolescents reporting dating violence received a tailored module on dating violence. the main outcome for this analysis was frequency of moderate and severe dating victimization and aggression at the baseline assessment and , , and months post ed visit. results: among eligible adolescents, % (n = ) reported dating violence and were included in these analyses. compared to controls, after controlling for baseline dating victimization, participants in the cbi showed reductions in moderate dating victimization at months (or . ; ci . - . ; p < . , effect size . ) and months (or . ; ci . - . ; p < . , effect size . ); models examining interaction effects were significant for the cbi on moderate dating victimization at and months. significant interaction effects were found for the tbi on moderate dating victimization at and months and severe dating victimization at months. the computer-based intervention shows promise for delivering content that decreases moderate dating victimization over months. the therapist bi is promising for decreasing moderate dating victimization over months and severe dating victimization over months. ed-based bis delivered on a computer addressing multiple risk behaviors could have important public health effects. figure . the -only ordinance was associated with a significant reduction of ar visits. this ordinance was also associated with reduction in underage ar visits, ui student visits, and public intoxication bookings. these data suggest that other cities should consider similar ordinances to prevent unwanted consequences of alcohol. background: prehospital providers perform tracheal intubation in the prehospital environment, and failed attempts are of concern due to the danger of hypoxia and hypotension. some question the appropriateness of intubation in this setting due to the morbidity risk associated with intubation in the field. thus it is important to gain an understanding of the factors that predict the success of prehospital intubation attempts to inform this discussion. objectives: to determine the factors that affect success rates on first attempt of paramedic intubations in a rapid sequence intubation (rsi) capable critical care transport service. methods: we conducted a multivariate logistic analysis on a prospectively collected database of airway management from an air and land critical care transport service that provides scene responses and interfacility transport in the province of ontario. background: motor vehicle collisions (mvcs) are one of the most common types of trauma for which people seek ed care. the vast majority of these patients are discharged home after evaluation. acute psychological distress after trauma causes great suffering and is a known predictor of posttraumatic stress disorder (ptsd) development. however, the incidence and predictors of psychological distress among patients discharged to home from the ed after mvcs have not been reported. objectives: to examine the incidence and predictors of acute psychological distress among individuals seen in the ed after mvcs and discharged to home. methods: we analyzed data from a prospective observational study of adults - years of age presenting to one of eight ed study sites after mvc between / and / . english-speaking patients who were alert and oriented, stable, and without injuries requiring hospital admission were enrolled. patient interview included assessment of patient sociodemographic and psychological characteristics and mvc characteristics. level of psychological distress in the ed was assessed using the -item peritraumatic distress inventory (pdi). pdi scores > are associated with increased risk of ptsd and were used to define substantial psychological distress. descriptive statistics and logistic regression were performed using stata ic . (statacorp lp, college station, texas). results: mvc patients were screened, were eligible, and were enrolled. / ( %) participants had substantial psychological distress. after adjusting for crash severity (severity of vehicle damage, vehicle speed), substantial patient distress was predicted by sociodemographic factors, pre-mvc depressive symptoms, and arriving to the ed on a backboard (table) . conclusion: substantial psychological distress is common among individuals discharged from the ed after mvcs and is predicted by patient characteristics separate from mvc severity. a better under standing of the frequency and predictors of substantial psychological distress is an important first step in identifying these patients and developing effective interventions to reduce severe distress in the aftermath of trauma. such interventions have the potential to reduce both immediate patient suffering and the development of persistent psychological sequelae. figure) the predictive characteristics of pets, pesi, and spesi for -day mortality in emperor, including auc, negative predictive value, sensitivity, and specificity were calculated. results: the of patients ( . %; % ci . %- . %) classified as pets low had -day mortality of . % ( % ci . - . %), versus . % ( % ci . %- . %) in the pets high group, statistically similar to pesi and spesi. pets is significantly more specific for mortality than the spesi ( . % v . %; p < . ), classifying far more patients as low-risk while maintaining a sensitivity of % ( % ci . %- . %), not significantly different from spesi or pesi (p > . ). conclusion: with four variables, pets in this derivation cohort is as sensitive for -day mortality as the more complicated pesi and spesi, with significantly greater specificity than the spesi for mortality, placing % more patients in the low-risk group. external validation is necessary. nicole seleno, jody vogel, michael liao, emily hopkins, richard byyny, ernest moore, craig gravitz, jason haukoos denver health medical center, denver, co background: the sequential organ failure assessment (sofa) score, base excess, and lactate have been shown to be associated with mortality in critically ill trauma patients. the denver emergency department (ed) trauma organ failure (tof) score was recently derived and internally validated to predict multiple organ failure in trauma patients. the relationship between the denver tof score and mortality has not been assessed or compared to other conventional measures of mortality in trauma. objectives: to compare the prognostic accuracies of the denver ed tof score, ed sofa score, and ed base excess and lactate for mortality in a large heterogeneous trauma population. methods: a secondary analysis of data from the denver health trauma registry, a prospectively collected database. consecutive adult trauma patients from through were included in the study. data collected included demographics, injury characteristics, prehospital care characteristics, response to injury characteristics, ed diagnostic evaluation and interventions, and in-hospital mortality. the values of the four clinically relevant measures (denver ed tof score, ed sofa score, ed base excess, and ed lactate) were determined within four hours of patient arrival, and prognostic accuracies for in-hospital mortality for the four measures were evaluated with receiver operating characteristic (roc) curves. multiple imputation was used for missing values. results: of the , patients, the median age was (iqr - ) years, median injury severity score was (iqr - ), and % had blunt mechanisms. thirty-eight percent ( , patients) were admitted to the icu with a median icu length of stay of . (iqr - ) days, and % ( patients) died. in the non-survivors, the median values for the four measures were ed sofa . (iqr . - . ); denver ed tof . (iqr . - . ); ed base excess . (iqr . - . ) meq/l; and ed lactate . (iqr . - . ) mmol/l. the areas under the roc curves for these measures are demonstrated in the figure. conclusion: the denver ed tof score more accurately predicts in-hospital mortality in trauma patients as compared to the ed sofa score, ed base excess, or ed lactate. the denver ed tof score may help identify patients early who are at risk for mortality, allowing for targeted resuscitation and secondary triage to improve outcomes in these critically ill patients. the background: both animal and human studies suggest that early initiation of therapeutic hypothermia (th) and rapid cooling improve outcomes after cardiac arrest. objectives: the objective was to determine if administration of cold iv fluids in a prehospital setting decreased time-to-target-temperature (tt) with secondary analysis of effects on mortality and neurological outcome. methods: patients resuscitated after out-of-hospital cardiac arrest (oohca) who received an in-hospital post cardiac arrest bundle including th were prospectively enrolled into a quality assurance database from november to november . on april , a protocol for intra-arrest prehospital cooling with °c normal saline on patients experiencing oohca was initiated. we retrospectively compared tt for those receiving prehospital cold fluids and those not receiving cold fluids. tt was defined as °c measured via foley thermistor. secondary outcomes included mortality, good neurological outcome defined as cerebral performance category (cpc) score of or at discharge, and effects of pre-rosc cooling. results: there were patients who were included in this analysis with patients receiving prehospital cold iv fluids and who did not. initially, % of patients were in vf/vt and % asystole/pea. patients receiving prehospital cooling did not have a significant improvement in tt ( minutes vs minutes, p = . ). survival to discharge and good neurologic outcome were not associated with prehospital cooling ( % vs %, p = . ) and cpc of or in % vs %, (p = . ). initiating cold fluids prior to rosc showed both a nonsignificant decrease in survival ( % vs %, p = . ) and increase in poor neurologic outcomes ( % vs %, p = . ). % of patients received £ l of cooled ivf prior to hospital arrival. patients receiving prehospital cold ivf had a longer time from arrest to hospital arrival ( vs min, p =< . ) in addition to a prolonged rosc to hospital time ( vs min, p = . ). conclusion: at our urban hospital, patients achieving rosc following oohca did not demonstrate faster tt or outcome improvement with prehospital cooling compared to cooling initiated immediately upon ed arrival. further research is needed to assess the utility of prehospital cooling. assessment background: an estimated % of emergency department (ed) patients years of age and older have delirium, which is associated with short-and long-term risk of morbidity and mortality. early recognition could result in improved outcomes, but the reliability of delirium recognition in the continuum of emergency care is unknown. objectives: we tested whether delirium can be reliably detected during emergency care of elderly patients by measuring the agreement between prehospital providers, ed physicians, and trained research assistants using the confusion assessment method for the icu (cam-icu) to identify the presence of delirium. our hypothesis was that both ed physicians and prehospital providers would have poor ability to detect elements of delirium in an unstructured setting. methods: prehospital providers and ed physicians completed identical questionnaires regarding their clinical encounter with a convenience sample of elderly (age > years) patients who presented via ambulance to two urban, teaching eds over a three-month period. respondents noted the presence or absence of ( ) an acute change in mental status, ( ) inattention, ( ) disorganized thinking, and ( ) altered level of consciousness (using the richmond agitation sedation scale). these four components comprise the operational definition of delirium. a research assistant trained in the cam-icu rated each component for the same patients using a standard procedure. we calculated inter-rater reliability (kappa) between prehospital providers, ed physicians, and research assistants for each component. objectives: this study aimed to assess the association between age and ems use while controlling for potential confounders. we hypothesized that this association use would persist after controlling for confounders. methods: a cross-sectional survey study was conducted at an academic medical center's ed. an interview-based survey was administered and included questions regarding demographic and clinical characteristics, mode of ed arrival, health care use, and the perceived illness severity. age was modeled as an ordinal variable (< , - , and ‡ years). bivariate analyses were used to identify potential confounders and effect measure modifiers and a multivariable logistic regression model was constructed. odds ratios were calculated as measures of effect. results: a total of subjects were enrolled and had usable data for all covariates, ( %) of whom arrived via ems. the median age of the sample was years and % were female. there was a statistically significant linear trend in the proportion of subjects who arrived via ems by age (p < . ). compared to adults aged less than years, the unadjusted odds ratio associating age and ems use was . ( % ci: background: we previously derived a clinical decision rule (cdr) for chest radiography (cxr) in patients with chest pain and possible acute coronary syndrome (acs) consisting of the absence of three predictors: history of congestive heart failure, history of smoking, and abnormalities on lung auscultation. objectives: to prospectively validate and refine a cdr for cxr in an independent patient population. methods: we prospectively enrolled patients over years of age with a primary complaint of chest pain and possible acs from september to january at a tertiary care ed with , annual patient visits. physicians completed standardized data collection forms before ordering chest radiographs and were thus blinded to cxr findings at the time of data collection. two investigators, blinded to the predictor variables, independently classified cxrs as ''normal,'' ''abnormal not requiring intervention,'' and ''abnormal requiring intervention'' (e.g, heart failure, infiltrates) based on review of the radiology report and the medical record. analyses included descriptive statistics, inter-rater reliability assessment (kappa), and recursive partitioning. results: of visits for possible acs, mean age (sd) was . ( . ) and % were female. twenty-four percent had a history of acute myocardial infarction, % congestive heart failure, and % atrial fibrillation. seventy-one ( . %, % ci . - . ) patients had a radiographic abnormality requiring intervention. ing the likelihood of coronary artery disease (cad) could reduce the need for stress testing or coronary imaging. acyl-coa:cholesterol acyltransferase- (acat ) activity has been shown in monkey and murine models to correlate with atherosclerosis. objectives: to determine if a novel cardiac biomarker consisting of plasma cholesteryl ester levels (ce) typically derived from the activity of acat is predictive of cad in a clinical model. methods: a single center prospective observational cohort design enrolled a convenience sample of subjects from a tertiary care center with symptoms of acute coronary syndrome undergoing coronary ct angiography or invasive angiography. plasma samples were analyzed for ce composition with mass spectrometry. the primary endpoint was any cad determined at angiography. multivariable logistic regression analyses were used to estimate the relationship between the sum of the plasma concentrations from cholesteryl palmitoleate ( : ) and cholesteryl oleate ( : ) (defined as acat -ce) and the presence of cad. the added value of acat -ce to the model was analyzed comparing the c-statistics and integrated discrimination improvement (idi). results: the study cohort was comprised of participants enrolled over months with a mean age (± . ) years, % with cad at angiography. the median plasma concentration of acat -ce was lm ( , ) in patients with cad and lm ( , ) in patients without cad (p = . ) (figure) . when considered with age, sex, and the number of conventional cad risk factors, acat -ce were associated with a . % increased odds of having cad per lm increase in concentration. the addition of acat -ce significantly improved the c-statistic ( . vs . , p = . ) and idi ( . , p < . ) compared to the reduced model. in the subgroup of low-risk observation unit patients, the ce model had superior discrimination compared to the diamond forrester classification (idi . , p < . ). conclusion: plasma levels of acat -ce, considered in a clinical model, have strong potential to predict a patient's likelihood of having cad. in turn, this could reduce the need for cardiac imaging after the exclusion of mi. further study of acat -ce as biomarkers in patients with suspected acs is needed. background: outpatient studies have demonstrated a correlation between carotid intima-media thickness (cimt) on ultrasound and coronary artery disease (cad). there are no known published studies that investigate the role of cimt in the ed using cardiac ct or percutaneous cardiac intervention (pci) as a gold standard. objectives: we hypothesized that cimt can predict cardiovascular events and serve as a noninvasive tool in the ed. methods: this was a prospective study of adult patients who presented to the ed and required evaluation for chest pain. the study location was an urban ed with a census of , annual visits and -hour cardiac catheterization. patients who did not have ct or pci or had carotid surgery were excluded from the study. ultrasound cimt measurements of right and left common carotid arteries were taken with a mhz linear transducer (zonare, mountain view, ca). anterior, medial, and posterior views of the near and far wall were obtained ( cimt scores total). images were analyzed by carotid analyzer (mailing imaging application llc, coralville, iowa). patients were classified into two groups based on the results from ct or pci. a subject was classified as having significant cad if there was over % occlusion or multi-vessel disease. results: ninety of patients were included in the study; . % were males. mean age was . ± years. there were ( . %) subjects with significant cad and ( . %) with non-significant cad. the mean of all cimt measurements was significantly higher in the cad group than in the non-cad group ( . ± . vs. . ± . ; p < . ). a logistic regression analysis was carried out with significant cad as the event of interest and the following explanatory variables in the model: objectives: to determine the diagnostic yield of routine testing in-hospital or following ed discharge among patients presenting to an ed following syncope. methods: a prospective, observational, cohort study of consecutive ed patients ‡ years old presenting with syncope was conducted. the four most commonly utilized tests (echocardiography, telemetry, ambulatory electrocardiography monitoring, and cardiac markers) were studied. interobserver agreement as to whether tests results determined the etiology of the syncope was measured using kappa (k) values. results: of patients with syncope, ( %) had echocardiography with ( %) demonstrating a likely etiology of the syncopal event such as critical valvular disease or significantly depressed left ventricular function (k = . ). on hospitalization, ( %) patients were placed on telemetry, ( %) of these had worrisome dysrhythmias (k = . ). ( %) patients had troponin levels drawn of whom ( %) had positive results (k = ); ( %) patients were discharged with monitoring with significant findings in only ( . %) patients (k = . ). overall, ( %, % ci - %) studies were diagnostic. conclusion: although routine testing is prevalent in ed patients with syncope, the diagnostic yield is relatively low. nevertheless, some testing, particularly echocardiography, may yield critical findings in some cases. current efforts to reduce the cost of medical care by eliminating non-diagnostic medical testing and increasing emphasis on practicing evidence-based medicine argue for more discriminate testing when evaluating syncope. (originally submitted as a ''late-breaker.'') unusual fatigue was reported by . % (severe . %) and insomnia by . % (severe . %). these findings have led to risk management recommendations to consider these symptoms as predictive of acute coronary syndromes (acs) among women visiting the ed. objectives: to document the prevalence of these symptoms among all women visiting an ed. to analyze the potential effect of using these symptoms in the ed diagnostic process for acs. methods: a survey on fatigue and insomnia symptoms was administered to a convenience sample of all adult women visiting an urban academic ed (all arrival modes, acuity levels, all complaints). a sensitivity analysis was performed using published data and expert opinion for inputs. results: we approached women, with enrollments. see table. the top box shows prevalences of prodromal symptoms among all adult female ed patients. the bottom box shows outputs from sensitivity analysis on the diagnostic effect of initiating an acs workup for all female ed patients reporting prodromal symptoms. conclusion: prodromal symptoms of acs are highly prevalent among all adult women visiting the ed in this study. this likely limits their utility in ed settings. while screening or admitting women with prodromal symptoms in the ed would probably increase sensitivity, that increase would be accompanied by a dramatic reduction in specificity. such a reduction in specificity would translate to admitting, observing, or working up somewhere between % and % of all women visiting the ed, which is prohibitive in terms of personal costs, risks of hospitalization, and financial costs. while these symptoms may or may not have utility in other settings such as primary care, their prevalence, and the implied lack of specificity for acs suggest they will not be clinically useful in the ed. length methods: we examined a cohort of low-risk chest pain patients evaluated in an ed-based ou using prospective and retrospective ou registry data elements. cox proportional hazard modeling was performed to assess the effect of testing modality (stress testing vs. ccta) on the los in the cdu. as ccta is not available on weekends, only subjects presenting on weekdays were included. cox models were stratified on time of patient presentation to the ed, based on four hour blocks beginning at midnight. the primary independent variable was first test modality, either stress imaging (exercise echo, dobutamine echo, stress mri) or ccta. age, sex, and race were included as covariates. the proportional hazards assumption was tested using scaled schoenfield residuals, and the models were graphically examined for outliers and overly influential covariate patterns. test selection was a time varying covariate in the am strata, and therefore the interaction with ln (los) was included as a correction term. after correction for multiple comparisons, an alpha of . was held to be significant. results: over the study period, subjects (of , in the registry) presented on non-weekend days. the median los was . hours (iqr . - . hours), % were white, and % were female. the table shows the number of subjects in each time strata, the number tested, and the number undergoing stress testing vs. ccta. after adjusting all models for age, race, and sex, the hazard ratio (hr) for los is as shown. only those patients presenting between am and noon noted a significant improvement in los with ccta use (p < . ). objectives: determine the validity of a managementfocused em osce as a measure of clinical skills by determining the correlation between osce scores and faculty assessment of student performance in the ed. methods: medical students in a fourth year em clerkship were enrolled in the study. on the final day of the clerkship students participated in a five-station em osce. student performance on the osce was evaluated using a task-based evaluation system with - critical management tasks per case. task performance was evaluated using a three-point system: performed correctly/timely ( ), performed incorrectly/late ( ), or not performed ( ). descriptive anchors were used for performance criteria. communication skills were also graded on a three-point scale. student performance in the ed was based on traditional faculty assessment using our core-competency evaluation instrument. a pearson correlation coefficient was calculated for the relationship between osce score and ed performance score. case item analysis included determination of difficulty and discrimination. the acgme also requires that trainees are evaluated on these ccs during their residency. trainee evaluation in the ccs are frequently on a subjective rating scale. one of the recognized problems with a subjective scale is the rating stringency of the rater, commonly known as the hawk-dove effect. this has been seen in standardized clinical exam scoring. recent data have shown that score variance can be related to evaluator performance with a negative correlation. higher-scoring physicians were more likely to be a stringent or hawk type rater on the same evaluation. it is unclear if this pattern also occurs in the subjective ratings that are commonly used in assessments of the ccs. objectives: comparison of attending physician scores on the acgme ccs with attending ratings of residents for a negative correlation or hawk-dove effect. methods: residents are routinely evaluated on the ccs with a - numerical rating scale as part of their training. the evaluation database was retrospectively reviewed. residents anonymously scored attending physicians on the ccs with a cross-sectional survey that utilized the same rating scale, anchors, and prompts as the resident evaluations. average scores for and by each attending were calculated and a pearson correlation calculated by core competency and overall. results: in this irb-approved study, a total of attending physicians were scored on the ccs with evaluations by residents. attendings evaluated residents with a total of , evaluations completed over a -year period. attending mode score was ranging from to ; resident scores had a mode of with a range of to . there was no correlation between the rated performance of the attendings overall or in each ccs and the scores they gave (p = . - . ). conclusion: hawk-dove effects can be seen in some scoring systems and has the potential to affect trainee evaluation on the acgme core competencies. however, a negative correlation to support a hawk-dove scoring pattern was not found in em resident evaluations by attending physicians. this study is limited by being a single center study and utilizing grouped data to preserve resident anonymity. background: all acgme-accredited residency programs are required to provide competency-based education and evaluation. graduating residents must demonstrate competency in six key areas. multiple studies have outlined strategies for evaluating competency, but data regarding residents' self-assessments of these competencies as they progress through training and beyond is scarce. objectives: using data from longitudinal surveys by the american board of emergency medicine, the primary objective of this study was to evaluate if resident self-assessments of performance in required competencies improve over the course of graduate medical training and in the years following. additionally, resident self-assessment of competency in academic medicine was also analyzed. methods: this is a secondary data analysis of data gathered from two rounds of the abem longitudinal study of emergency medicine residents ( - and - ) and three rounds of the abem longitudinal study of emergency physicians ( , , ). in both surveys, physicians were asked to rate a list of items in response to the question, ''what is your current level of competence in each of the following aspects of work in em?'' the rated items were grouped according to the acgme required competencies of patient care, medical knowledge, practice-based learning and improvement, interpersonal and communication skills, and system-based practice. an additional category for academic medicine was also added. results: rankings improved in all categories during residency training. rankings in three of the six categories improved from the weak end of the scale to the strong end of the scale. there is a consistent decline in rankings one year after graduation from residency. the greatest drop is in medical knowledge. mean self-ranking in academic medicine competency is uniformly the lowest ranked category for each year. conclusion: while self-assessment is of uncertain value as an objective assessment, these increasing rankings suggest that emergency medicine residency programs are successful at improving residents' confidence in the required areas. residents do not feel as confident about academic medicine as they do about the acgme required competencies. the uniform decline in rankings the first year after residency is an area worthy of further inquiry. screening medical student rotators from outside institutions improves overall rotation performance shaneen doctor, troy madsen, susan stroud, megan l. fix university of utah, salt lake city, ut background: emergency medicine is a rapidly growing field. many student rotations are limited in their ability to accommodate all students and must limit the number of students they allow per rotation. we hypothesize that pre-screening visiting student rotators will improve overall student performance. objectives: to assess the effect of applicant screening on overall rotation grade and mean end of shift card scores. methods: we initiated a medical student screening process for all visiting students applying to our -week elective em rotation starting in . this consisted of reviewing board scores and requiring a letter of intent. students from our home institution were not screened. all end-of-shift evaluation cards and final rotation grades (honors, high pass, pass, fail) from to were analyzed. we identified two cohorts: home students (control) and visiting students. we compared pre-intervention ( ) ( ) ( ) ( ) ( ) and postintervention ( - ) scores and grades. end of shift performance scores are recorded using a fivepoint scale that assesses indicators such as fund of knowledge, judgment, and follow-through to disposition. mean ranks were compared and p-values were calculated using the armitage test of trend and confirmed using t-tests. results: we identified visiting students ( pre, post) and home students ( pre, post). ( . %) visiting students achieved honors pre-intervention while ( . %) achieved honors post-intervention (p = . ). no significant difference was seen in home student grades: ( . %) received honors pre- and ( . %) received honors post- conclusion: we found that implementation of a screening process for visiting medical students improved overall rotation scores and grades as compared to home students who did not receive screening. screening rotating students may improve the overall quality of applicants and thereby the residency program. background: there are many descriptions in the literature of computer-assisted instruction in medical education, but few studies that compare them to traditional teaching methods. objectives: we sought to compare the suturing skills and confidence of students receiving video preparation before a suturing workshop versus a traditional instructional lecture. methods: first and second year medical students were randomized into two groups. the control group was given a lecture followed by minutes of suturing time. the video group was provided with an online suturing video at home, no lecture, and given minutes of suturing time during the workshop. both groups were asked to rate their confidence before and after the workshop, and their belief in the workshop's effectiveness. each student was also videotaped suturing a pig's foot after the workshop and graded on a previously validated -point suturing checklist. videos were scored. results: there was no significant difference between the test scores of the lecture group (m = . , sd = . , n = ) and the video group (m = . , sd = . , n = ) using the two-sample independent ttest for equal variances (t( ) = ) . , p = . ). there was a statistically significant difference in the proportion of students scoring correctly for only one point: ''curvature of needle followed'': / in the lecture group and / in the video group (chi = . , df = , p = . ). students in the video group were found to be . times more likely to have a neutral or favorable feeling of suturing confidence before the workshop (p = . , ci . - . ) using a proportional odds model. no association was detected between group assignment and level of suturing confidence after the workshop (p = . ). there was also no association detected between group assignment and opinion of the suturing workshop (p = . ) using a logistic regression odds model. among those students who indicated a lack of confidence before training, there was no detected association (p = . ) between group assignment and having an improved confidence using a logistic regression odds model. conclusion: students in the video group and students in the control group achieved similar levels of suturing skill and confidence, and equal belief in the workshop's effectiveness. this study suggests that video instruction could be a reasonable substitute for lectures in procedural education. background: accurate interpretation of the ecg in the emergency department is not only clinically important but also critical to assess medical knowledge competency. with limitations to expansion of formal didactics, educational technology offers an innovative approach to improve the quality of medical education. objectives: the aim of this study was to assess an online multimedia-based ecg training module evaluating st elevation myocardial infarction (stemi) identification among medical students. methods: a convenience sample of fifty-two medical students on their em rotations at an academic medical center with an em residency program was evaluated in a before-after fashion during a -month period. one cardiologist and two ed attending physicians independently validated a standardized exam of ten ecgs: four were normal ecgs, three were classic stemis, and three were subtle stemis. the gold standard for diagnosis was confirmed acute coronary thrombus during cardiac catheterization. after evaluating the ecgs, students completed a pre-intervention test wherein they were asked to identify patients who required emergent cardiac catheterization based on the presence or absence of st segment elevation on ecg. students then completed an online interactive multimedia module containing minutes of stemi training based on american heart association/american college of cardiology guidelines on stemi. medical students were asked to complete a post-test of the ecgs after watching online multimedia. objectives: our objective was to quantify the number of pre-verbal pediatric head cts performed at our community hospital that could have been avoided by utilizing the pecarn criteria. methods: we conducted a standardized chart review of all children under the age of who presented to our community hospital and received a head ct between jan st, and dec st, . following recommended guidelines for conducting a chart review, we: ) utilized four blinded chart reviewers, ) provided specific training, ) created a standardized data extraction tool, and ) held periodic meetings to evaluate coding discrepancies. our primary outcome measure was the number of patients who were pecarn negative and received a head ct at our institution. our secondary outcome was to reevaluate the sensitivity and specificity of the pecarn criteria to detect citbi in our cohort. data were analyzed using descriptive statistics and % confidence intervals were calculated around proportions using the modified wald method. results: a total of patients under the age of received a head ct at our institution during the study period. patients were excluded from the final analysis because their head cts were not for trauma. the prevalence of a citbi in our cohort was . % ( % ci . %- . %) ( (dti) measures disruption of axonal integrity on the basis of anisotropic diffusion properties. findings on dti may relate to the injury, as well as the severity of postconcussion syndrome (pcs) following mtbi. objectives: to examine acute anisotropic diffusion properties based on dti in youth with mtbi relative to orthopedic controls and to examine associations between white matter (wm) integrity and pcs symptoms. methods: interim analysis of a prospective casecontrol cohort involving youth ages - years with mtbi and orthopedic controls requiring extremity radiographs. data collected in ed included demographics, clinical information, and pcs symptoms measured by the postconcussion symptom scale. within hours of injury, symptoms were re-assessed and a -direction, diffusion weighted, spin-echo imaging scan was performed on a t philips scanner. dti images were analyzed using tract-based spatial statistics. fractional anisotropy (fa), mean diffusivity (md), axial diffusivity (ad), and radial diffusivity were measured. results: there were no group demographic differences between mtbi cases and controls. presenting symptoms within the mtbi group included gcs = %, loss of consciousness %, amnesia %, post-traumatic seizure %, headache %, vomiting %, dizziness %, and confusion %. pcs symptoms were greater in mtbi cases than in the controls at ed visit ( . ± . vs. . ± . , p < . ) and at the time of scan ( . ± . vs. . ± . , p < . ). the mtbi group displayed decreased fa in cerebellum and increased md and ad in the cerebral wm relative to controls (uncorrected p < . ). increased fa in cerebral wm was also observed in mtbi patients but the group difference was not significant. pcs symptoms at the time of the scan were positively correlated with fa and inversely correlated with rd in extensive cerebral wm areas (p < . , uncorrected). in addition, pcs symptoms in mtbi patients were also found to be inversely correlated with md, ad, and rd in cerebellum (p < . ). conclusion: dti detected axonal damage in youth with mtbi which correlated with pcs symptoms. dti performed acutely after injury may augment detection of injury and help prediction of those with worse outcomes. background: sports-related concussion among professional, collegiate, and more recently high school athletes has received much attention from the media and medical community. to our knowledge, there is a paucity of research in regard to sports-related concussion in younger athletes. objectives: the aim of this study was to evaluate parental knowledge of concussion in young children who participate in recreational tackle football. methods: parents/legal guardians of children aged - years enrolled in recreational tackle football were asked to complete an anonymous questionnaire based on the cdc's heads up: concussion in youth sports quiz. parents were asked about their level of agreement in regard to statements that represent definition, symptoms, and treatment of concussion. results: a total of out of parents voluntarily completed the questionnaire ( % response rate). parent and child demographics are listed in table . ninety four percent of parents believed their child had never suffered a concussion. however, when asked to agree or disagree with statements addressing various aspects of concussion, only % (n = ) could correctly identify all seven statements. most did not identify that a concussion is considered a mild traumatic brain injury and can be achieved from something other than a direct blow to the head. race, sex, and zip code had no significant association with correctly answering statements. education ( . ; p < . ) and number of years the child played ( . ; p < . ) had a small effect. fifty-three percent of parents reported someone had discussed the definition of concussion with them and % the symptoms of concussion. see table for source of information to parents. no parent was able to classify all symptoms listed as correctly related or not related to concussion. however, identification of correct concussion definitions correlated with identification of correct symptoms ( . ; p < . ). conclusion: while most parents had received some education regarding concussion from a health care provider, important misconceptions remain among parents of young athletes regarding the definition, symptoms, and treatment of concussion. this study highlights the need for health care providers to increase educational efforts among parents of young athletes in regard to concussion. figure ). / ( %) of patients with baseline liver dysfunction were (oh)d deficient and / ( %) of deaths were patients who had insufficient levels of (oh)d. there was an inverse association between (oh)d level and tnf-a (p = . ; figure ) and il- (p = . ). background: fever is common in the emergency department (ed), and % of those diagnosed with severe sepsis present with fever. despite data suggesting that fever plays an important role in immunity, human data conflict on the effect of antipyretics on clinical outcomes in critically ill adults. objectives: to determine the effect of ed antipyretic administration on -day in-hospital mortality in patients with severe sepsis. methods: single-center, retrospective observational cohort study of febrile severe sepsis patients presenting to an urban academic , -visit ed between june and june . all ed patients meeting the following criteria were included: age ‡ , temperature ‡ . °c, suspected infection, and either systolic blood pressure £ mmhg after a ml/kg fluid bolus or lactate of ‡ . patients were excluded for a history of cirrhosis or acetaminophen allergy. antipyretics were defined as acetaminophen, ibuprofen, or ketorolac. results: one hundred-thirty five ( . %) patients were treated with an antipyretic medication ( . % acetaminophen). intubated patients were less likely to receive antipyretic therapy ( . % vs. . %, p < . ), but the groups were otherwise well matched. patients requiring ed intubation (n = ) had much higher in-hospital mortality ( . % vs. . %, p < . ). patients given an antipyretic in the ed had lower mortality ( . % vs. . %, p < . ). when multivariable logistic regression was used to account for apache-ii, intubation status, and fever magnitude, antipyretic therapy was not associated with mortality (adjusted or . , . - . , p = . ). conclusion: although patients treated with antipyretic therapy had lower -day in-hospital mortality, antipyretic therapy was not independently associated with mortality in multivariable regression analysis. these findings are hypothesis-generating for future clinical trials, as the role of fever control has been largely unexplored in severe sepsis (grant ul rr , nih-ncrr). , and caval index ) . ± . (ci ) . , ) . ) and all were statistically significant. the groups receiving ml/kg and ml/kg had statistically significant changes in caval index; however the ml/kg group had no significant change in mean ivc diameter. one-way anova differences between the means of all groups were not statistically different. conclusion: overall, there were statistically significant differences in mean ivc-us measurements before and after fluid loading, but not between groups. fasting asymptomatic subjects had a wide inter-subject variation in both baseline ivc-us measurements and fluid-related changes. the wide differences within our ml/kg group may limit conclusions regarding proportionality. there were significant differences in performance on ed measures by ownership (p < . ) and region (p = . ). scores on ed process measures were highest at for-profit hospitals ( % above average) and hospitals in the south ( % above average), and lowest at public hospitals ( % below average) and hospitals in the northeast ( % below average). conclusion: there was considerable variation in performance on the ed measures included in the vbp program by hospital ownership and region. ed directors may come under increasing pressure to improve scores in order to reduce potential financial losses under the program. our data provide early information on the types of hospitals with the greatest opportunity for improvement. methods: design/setting -an independent agency mandated by the government collected and analyzed ed patient experience data using a comprehensive, validated multidimensional instrument and a random periodic sampling methodology of all ed patients. a prospective pre-post experimental study design was employed in the eight community and tertiary care hospitals most affected by crowding. two . month study periods were evaluated (pre: / - / / ; post: / / - / / ). outcomes -the primary outcome was patient perception of wait times and crowding reported as a composite mean score ( - ) from six survey items with higher scores representing better ratings. the overall rating of care by ed patients (composite score) and other dimensions of care were collected as secondary outcomes. all outcomes were compared using chi-square and two-tailed student's t-tests. results: a total of surveys were completed in both the pre-ocp and post-ocp study periods representing a response rate of %. we compared in-patient mortality from ami for patients who lived in a community with either . miles or miles of a closure but did not need to travel farther to the nearest ed with those who did not. we used patient-level data from the california office of statewide health and planning development (oshpd) database patient discharge data, and locations of patient residence and hospitals were geo-coded to determine any changes in distance to the nearest ed. we applied a generalized linear mixed effects model framework to estimate a patient's likelihood to die in the hospital of ami as a function of being affected by a neighborhood closure event. results background: fragmentation of care has been recognized as a problem in the us health care system. however, little is known about ed utilization after hospitalization, a potential marker of poor outpatient care coordination after discharge, particularly for common inpatient-based procedures. objectives: to determine the frequency and variability in ed visits after common inpatient procedures, how often they result in readmission, and related payments. methods: using national medicare data for - , we examined ed visits within days of hospital discharge after six common inpatient procedures: percutaneous coronary intervention, coronary artery bypass grafting (cabg), elective abdominal aortic aneurysm repair, back surgery, hip fracture repair, and colectomy. we categorized hospitals into risk-adjusted quintiles based on the frequency of ed visits after the index hospitalization. we report visits by primary diagnosis icd- codes and rates of readmission. we also assessed payments related to these ed visits. results: overall, the highest quintile of hospitals had -day ed visit rates that ranged from a low of . % with an associated . % readmission rate (back surgery) to a high of . % with an associated . % readmission rate (cabg). the most variability was more than -fold and found among patients undergoing colectomy in which the worst-performing hospitals saw . % of their patients experienced an ed visit within days while the best-performing hospitals saw . %. average total payments for the -day window from initial discharge across all surgical cohorts varied from $ , for patients discharged without subsequent ed visit; $ , for those experiencing an ed visit(s); $ , for those readmitted through the ed; and $ , for those readmitted from another source. if all patients who did not require readmission also did not incur an ed visit within the -day window, this would represent a potential cost savings of $ million. conclusion: among elderly medicare recipients there was significant variability between hospitals for -day ed visits after six common inpatient procedures. the ed visit may be a marker of poor care coordination in the immediate discharge period. this presents an opportunity to improve post-procedure outpatient care coordination which may save costs related to preventable ed visits and subsequent readmissions. objectives: we sought to assess the effect of pharmacist medication review on ed patient care, in particular time from physician order to medication administration for the patient (order-to-med time). methods: we conducted a multi-center, before-after study in two eds (urban academic teaching hospital and suburban community hospital, combined census of , ) after implementation of the electronic prospective pharmacy review system (prs). the system allowed a pharmacist to review all ed medication orders electronically at the time of physician order and either approve or alter the order. we studied a -month time period before implementation of the system (pre-prs, / / - / / ) and after implementation (post-prs, / / - / / ). we collected data on all ed medication orders including dose, route, class, pharmacist review action, time of physician order, and time of medication administration. differences in order-to-medication between the pre-and post-prs study periods were compared using a results: ed metrics that were significantly associated with lbtcs varied across ed patient-volume categories (table) . for eds seeing less than k patients annually, the percentage of ems arrivals admitted to the hospital and ed square footage were both weakly associated with lbtcs (p = . ). for eds seeing at least k- k patients, median ed length of stay (los), percent of patients admitted to hospital through the ed, percent of ems arrivals admitted to hospital, and percent of pediatric patients were all positively associated, while percent of patients admitted to the hospital was negatively associated with lbtcs. for eds seeing k- k, median los and percent of x-rays performed were positively associated, while percent of ekgs performed was negatively associated with lbtcs. for eds seeing k- k, percent of patients admitted to the hospital through the ed was negatively associated and percent of ekgs performed was positively associated with lbtcs. for eds with volume greater than k, none of the selected variables were associated with lbtc. conclusion: ed factors that help explain high lbtc rates differ depending on the size of an ed. interventions attempting to improve lbtc rates by modifying ed structure or process will need to consider baseline ed volume as a potential moderating influence. objectives: our study sought to compare bacterial growth of samples taken from surfaces after use of a common approved quat compound and a virtually non-toxic, commercially available solution containing elemental silver ( . %), hydrogen peroxide ( %), and peroxyacetic acid ( %) (shp) in a working ed. we hypothesized that, based on controlled laboratory data available, shp compound would be more effective on surfaces in an active urban ed. methods: we cleaned and then sampled three types of surfaces in the ed (suture cart, wooden railing, and the floor) during midday hours one minute after application of tap water, quat, and shp and then again at hours without additional cleaning. conventional environmental surface surveillance rodac media plates were used for growth assessment. images of bacterial growth were quantified at and hours. standard cleaning procedures by hospital staff were maintained per usual. results: shp was superior to control and quat one minute after application on all three surfaces. quat and water had x and x more bacterial growth than the surface cleaned with shp, respectively. hours later, the shp area produced fewer colonies sampled from the wooden railing: x more bacteria for quat, and x for water when compared to shp. h cultures from the cart and floor had confluent growth and could not be quantified. conclusion: shp outperforms quat in sterilizing surfaces after one minute application. shp may be a superior agent as a non-toxic, non-corrosive, and effective agent for surfaces in the demanding ed setting. further studies should examine sporidical and virucidal properties in a similar environment. objectives: evaluate the effect on patient satisfaction of increasing waiting room times and physician evaluation times. methods: emergency department flow metrics were collected on a daily basis as well as average daily patient satisfaction scores. the data were from july through february , in a , census urban hospital. the data were divided into equal intervals. the arrival to room time was divided by minute intervals up to minutes with the last group being greater than minutes. the physician evaluation times were divided into minute intervals, up to , the last group greater than with days in the group. data were analyzed using means and standard deviations, and well as anova for comparison between groups. results: the overall satisfaction score for the outpatient emergency visit was higher when the patient was in a room within minutes of arrival ( . , std deviation . ), analysis of variation between the groups had a p = . , for the means of each interval (see table ). the total satisfaction with the visit as well as satisfaction with the provider dropped when the evaluation extended over minutes, but was not statistically significant on anova analysis (see table for means). conclusion: once a patient's time in the waiting room extends beyond minutes, you have lost a significant opportunity for patient satisfaction; once they have been in the waiting room for over minutes, you are also much more likely to receive a poor score. physician evaluation time scores are much more consistent but as longer evaluation times occurred beyond total of minutes we started to see a trend downward in the satisfaction score. results: in all three eds, pain medication rates (both in ed and rx) varied significantly by clinical factors including location of pain, discharge diagnosis, pain level, and acuity. we observed little to no variation in pain medication rates by patient factors such as age, sex, race, insurance, or prior ed visits. the table displays key pain management practices by site and provider. after adjusting for patient and clinical characteristics, significant differences in pain medication rates remained by provider and site (see figure) . conclusion: within this health system, the approach to pain management by both providers and sites is not standardized. investigation of the potential effect of this variability on patient outcomes is warranted. results: all measures showed significant differences, p < . . average pts/h decreased post-cpoe and did not recover post transitional period, . ± . vs . ± . , p < . . rvu/h also decreased post-cpoe and did not recover post transitional period, . ± . vs . ± . and . ± . , p < . . charges/h also decreased after cpoe implementation and did not recover after system optimization. there was a sustained significant decrease in charges/h of . % ± . % post cpoe and . % ± . % post optimization, p < . . sub-group analysis for each provider group was also evaluated and showed variability for different providers. conclusion: there was a significant decrease in all productivity metrics four months after the implementation of cpoe. the system did undergo optimization initiated by providers with customization for ease and speed of use. however, productivity measurements did not recover after these changes were implemented. these data show that with the implementation of a cpoe system there is a decrease in productivity that continues even after a transition period and system customization. background: procedural competency is a key component of emergency medicine residency training. residents are required to log procedures to document quantity of procedures and identify potential weaknesses in their training. as emergency medicine evolves, it is likely that the type and number of procedures change over time. also, exposure to certain rare procedures in residency is not guaranteed. objectives: we seek to delineate trends in type and volume of core em procedures over a decade of emergency medicine residents graduating from an accredited four-year training program. methods: deidentified procedure logs from - were analyzed to assess trends in type and quantity of procedures. procedure logs were self-reported by individual residents on a continuous basis during training onto a computer program. average numbers of procedures per resident in each graduating class were noted. statistical analysis was performed using spss and includes a simple linear regression to evaluate for significant changes in number of procedures over time and an independent samples two-tailed t-test of procedures performed before and after the required resident duty hours change. results: a total of procedure logs were analyzed and the frequency of different procedures was evaluated. a significant increase was seen in one procedure, the venous cutdown. significant decreases were seen in procedures including key procedures such as central venous catheters, tube thoracostomy, and procedural sedation. the frequency of five high-stakes/ resuscitative procedures, including thoracotomy and cricothyroidotomy, remained steady but very low (< per resident over years). of the remaining procedures, showed a trend toward decreased frequency, while only increased. conclusion: over the past years, em residents in our program have recorded significantly fewer opportunities to perform most procedures. certain procedures in our emergency medicine training program have remained stable but uncommon over the course of nearly a decade. to ensure competency in uncommon procedures, innovative ways to expose residents to these potentially life saving skills must be considered. these may include practice on high-fidelity simulators, increased exposure to procedures on patients during residency (possibly on off-service rotations), or practice in cadaver and animal labs. objectives: to study the effectiveness of a unique educational intervention using didactic and hands-on training in usgpiv. we hypothesized that senior medical students would improve performance and confidence with usgpiv after the simulation training. methods: fourth year medical students were enrolled in an experimental, prospective, before and after study conducted at a university medical school simulation center. baseline skills in participant's usgpiv on simulation vascular phantoms were graded by ultrasound expert faculty using standardized checklists. the primary outcome was time to cannulation, and secondary outcomes were ability to successfully cannulate, number of needle attempts, and needle-tip visualization. subjects then observed a -minute presentation on correct performance of usgpiv followed by a -minute hands-on practical session using the vascular simulators with a : to : ultrasound instructor to student ratio. an expert blinded to the participant's initial performance graded post-educational intervention usgpiv ability. pre-and post-intervention surveys were obtained to evaluate usgpiv confidence, previous experience with ultrasound, peripheral iv access, usg-piv, and satisfaction with the educational format. objectives: this study examines the grade distribution of resident evaluations when the identity of the evaluator was anonymous as compared to when the identity of the evaluator was known to the resident. we hypothesize that there will be no change in the grades assigned to residents. methods: we retrospectively reviewed all faculty evaluations of residents and grades assigned from july , through november , . prior to july , the identity of the faculty evaluators was anonymous, while after this date, the identity of the faculty evaluators was made known to the residents. throughout this time period, residents were graded on a five-point scale. each resident evaluation included grades in the six acgme core competencies as well as in select other abilities. specific abilities evaluated varied over the dates analyzed. evaluations of residents were assigned to two groups, based on whether the evaluator was anonymous or made known to the resident. grades were compared between the two groups. results: a total of , grades were assigned in the anonymous group, with an average grade of . ( ci . , . ). a total of , grades were assigned in the known group with an average grade of . ( ci . , . ). specific attention was paid to assignment of unsatisfactory grades ( or on the five-point scale). the anonymous group assigned grades in this category, comprising . % of all grades assigned. the known group assigned grades in this category, comprising . % of all grades assigned. unsatisfactory grades were assigned by the anonymous group . % ( ci . , . ) more often. additionally, . % ( ci . , . ) fewer exceptional grades ( or on the five-point scale) were assigned by the anonymous group. conclusion: the average grade assigned was closer to average ( on a five-point scale) when the identity of the evaluator was made known to the residents. additionally, fewer unsatisfactory and exceptional grades were assigned in this group. this decrease of both unsatisfactory and exceptional grades may make it more difficult for program directors to effectively identify struggling and strong residents respectively. testing to improve knowledge retention from traditional didactic presentations: a pilot study david saloum, amish aghera, brian gillett maimonides medical center, brooklyn, ny background: the acgme requires an average of at least hours of planned educational experiences each week for em residents, which traditionally consists of formal lecture based instruction. however, retention by adult learners is limited when presented material in a lecture format. more effective methods such as small group sessions, simulation, and other active learning modalities are time-and resource-intensive and therefore not practical as a primary method of instruction. thus, the traditional lecture format remains heavily relied upon. efficient strategies to improve the effectiveness of lectures are needed. testing utilized as a learning tool to force immediate recall of lecture material is an example of such a strategy. objectives: to evaluate the effect of immediate postlecture short answer quizzes on em residents' retention of lecture content. methods: in this prospective randomized controlled study, em residents from a community based -year training program were randomized into two groups. block randomization provided a similar distribution of postgraduate year training levels and performance on both us-mle and in-training examinations between the two groups. each group received two identical -minute lectures on ecg interpretation and aortic disease. one group of residents completed a five-question short answer quiz immediately following each lecture (n = ), while the other group received the lectures without subsequent quizzes (n = ). the quizzes were not scored or reviewed with the residents. two weeks later, retention was assessed by testing both groups with a -question multiple choice test (mct) derived in equal part from each lecture. mean and median test results were then compared between groups. statistical significance was determined using a paired t-test of median test scores from each group. results: residents who received immediate post-lecture quizzes demonstrated significantly higher mct scores (mean = %, median %, n = ) compared to those receiving lectures alone (mean = %, median = %, n = ); p = . . conclusion: short answer testing immediately after a traditional didactic lecture improves knowledge retention at a -week interval. limitations of the study are that it is a single center study and long term retention was not assessed. background: the task of educating the next generation of physicians is steadily becoming more difficult with the inherent obstacles that exist for faculty educators and the work hour restrictions that students must adhere to. the obstacles make developing curricula that not only cover important topics but also do so in a fashion that helps support and reinforce the clinical experiences very difficult. several areas of medical education are using more asynchronous techniques and self-directed online educational modules to overcome these obstacles. objectives: the aim of this study was to demonstrate that educational information pertaining to core pediatric emergency medicine topics could be as effectively disseminated to medical students via self-directed online educational modules as it could through traditional didactic lectures. methods: this was a prospective study conducted from august , through december , . students participating in the emergency medicine rotation at carolinas medical center were enrolled and received education in a total of eight core concepts. the students were divided into two groups which changed on a monthly basis. group was taught four concepts via self-directed online modules and four traditional didactic lectures. group was taught the same core concepts, but in opposite fashion to group . each student was given a pre-test, post-test, and survey at the conclusion of the rotation. results: a total of students participated in the study. students, regardless of which group assigned, performed similarly on the pre-test, with no statistical difference among scores. when looking at the summative total scores between online and traditional didactic lectures, there was a trend towards significance for more improvement among those taught online. the student's assessment of the online modules showed that the majority either felt neutral or preferred the online method. the majority thought the depth and length of the modules were perfect. most students thought having access to the online modules was valuable and all but one stated that they would use them again. conclusion: this study demonstrates that self-directed, online educational modules are able to convey important concepts in emergency medicine similar to traditional didactics. it is an effective learning technique that offers several advantages to both the educator and student. background: critical access hospitals (cah) provide crucial emergency care to rural populations that would otherwise be without ready access to health care. data show that many cah do not meet standard adult quality metrics. adults treated at cah often have inferior outcomes to comparable patients cared for at other community-based emergency departments (eds). similar data do not exist for pediatric patients. objectives: as part of a pilot project to improve pediatric emergency care at cah, we sought to determine whether these institutions stock the equipment and medications necessary to treat any ill or injured child who presents to the ed. methods: five north carolina cah volunteered to participate in an intensive educational program targeting pediatric emergency care. at the initial site visit to each hospital, an investigator, in conjunction with the ed nurse manager, completed a -item checklist of commonly required ed equipment and medications based on the acep ''guidelines for care of children in the emergency department''. the list was categorized into monitoring and respiratory equipment, vascular access supplies, fracture and trauma management devices, and specialized kits. if available, adult and pediatric sizes were listed. only hospitals stocking appropriate pediatric sizes of an item were counted as having that item. the pharmaceutical supply list included antibiotics, antidotes, antiemetics, antiepileptics, intubation and respiratory medications, iv fluids, and miscellaneous drugs not otherwise categorized. results: overall, the hospitals reported having % of the items listed (range - %). the two greatest deficiencies were fracture devices (range - %), with no hospital stocking infant-sized cervical collars, and antidotes, with no hospital stocking pralidoxime, / hospitals stocking fomepizole, and / hospitals stocking pyridoxine and methylene blue. only one of the five institutions had access to prostaglandin e. the hospitals stated cost and rarity of use as the reason for not stocking these medications. conclusion: the ability of cah to care for pediatric patients does not appear to be hampered by a lack of equipment. ready access to infrequently used, but potentially lifesaving, medications is a concern. tertiary care centers preparing to accept these patients should be aware of these potential limitations as transport decisions are made. background: while incision and drainage (i&d) alone has been the mainstay of management of uncomplicated abscesses for decades, some advocate for adjunct antibiotic use, arguing that available trials are underpowered and that antibiotics reduce treatment failures and recurrence. objectives: to investigate the role of antibiotics in addition to i&d in reducing treatment failure as compared to management with i&d alone. methods: we performed a search using medline, embase, web of knowledge, and google scholar databases (with a medical librarian) to include trials and observational studies analyzing the effect of antibiotics in human subjects with skin and soft-tissue abscesses. two investigators independently reviewed all the records. we performed three overlapping meta-analy-ses: . only randomized trials comparing antibiotics to placebo on improvement of the abscess during standard follow-up. . trials and observational studies comparing appropriate antibiotics to placebo, no antibiotics, or inappropriate antibiotics (as gauged by wound culture) on improvement during standard follow-up. . only trials, but broadened outcome to include recurrence or new lesions during a longer follow-up period as treatment failure. we report pooled risk ratios (rr) using a fixed-effects model for our point estimates with shore-adjusted % confidence intervals (ci). results: we screened , records, of which studies fit inclusion criteria, of which were meta-analyzed ( trials, observational studies) because they reported results that could be pooled. of the studies, enrolled subjects from the ed, from a soft-tissue infection clinic, and from a general hospital without definition of enrollment site. five studies enrolled primarily adults, pediatrics, and without specification of ages. after pooling results for all randomized trials only, the rr = . ( % ci: . - . ). exposure being ''appropriate'' antibiotics (using trials and observational studies) resulted in a pooled rr = . ( % ci: . - . ). when we broadened our treatment failure criteria to include recurrence or new lesions at longer lengths of follow-up (trials only), we noted a rr = . ( % ci: . - . ). conclusion: based on available literature pooled for this analysis, there is no evidence to suggest any benefit from antibiotics in addition to i&d in the treatment of skin and soft tissue abscesses. (originally submitted as a ''late-breaker.'') primary objectives: to compare wound healing and recurrence rates after primary vs. secondary closure of drained abscesses. we hypothesized the percentage of drained ed abscesses that would be completely healed at days would be higher after primary closure. methods: this randomized clinical trial was undertaken in two academic emergency departments. immunocompetent adult patients with simple, localized cutaneous abscesses were randomly assigned to i & d followed by primary or secondary closure. randomization was balanced by center, with an allocation sequence based on a block size of four, generated by a computer random number generator. the primary outcome was percentage of healed wounds seven days after drainage. a sample of patients had % power to detect an absolute difference of % in healing rates assuming a baseline rate of %. all analyses were by intention to treat. results: twenty-seven patients were allocated to primary and to secondary closure, of whom and , respectively, were followed to study completion. healing rates at seven days were similar between the primary and secondary closure groups ( we compared consecutive patients each scanned on the or slice ccta in - . measures and outcomes-data were prospectively collected using standardized data collection forms required prior to performing ccta. the main outcomes were cumulative radiation doses and volumes of intravenous contrast. data analysis-groups compared with t-, mann whitney u, and chi-square tests. results: the mean age of patients imaged with the and scanners were (sd ) vs. ( ) (p = . ). male:female ratios were also similar ( : vs. : respectively, p = . ). both mean (p < . ) and median (p = . ) effective radiation dose were significantly lower with the ( . and msv) vs. the -slice scanner ( . and msv) respectively. prospective gating was successful in % of the scans and only in % of the scans (p < . ). mean iv contrast volumes were also lower for the vs. the -slice scanner ( ± vs. ± ml; p < . ). the % non-diagnostic scans was similarly low in both scanners ( % each). there were no differences in use of beta-blockers or nitrates. conclusion: when compared with the -slice scanner, the -slice scanner reduces the effective radiation doses and iv contrast volumes in ed patients with cp undergoing ccta. need for beta-blockers and nitrates was similar and both scanners achieved excellent diagnostic image quality. background: a few studies have demonstrated that bedside ultrasound measurement of inferior vena cava to aorta (ivc-to-ao) ratio is associated with the level of dehydration in pediatric patients and a proposed cutoff of . has been suggested, below which a patient is considered dehydrated. objectives: we sought to externally validate the ability of ivc-to-ao ratio to discriminate dehydration and the proposed cutoff of . in an urban pediatric emergency department (ed). methods: this was a prospective observational study at an urban pediatric ed. we included patients aged to months with clinical suspicion of dehydration by the ed physician and an equal number of control patients with no clinical suspicion of dehydration. we excluded children who were hemodynamically unstable, had chronic malnutrition or failure to thrive, open abdominal wounds, or were unable to provide patient or parental consent. a validated clinical dehydration score (cds) (range to ) was used to measure initial dehydration status. an experienced sonographer blinded to the cds and not involved in the patient's care measured the ivc-to-ao ratio on the patient prior to any hydration. cds was collapsed into a binary outcome of no dehydration or any level of dehydration ( or higher). the ability of ivc-to-ao ratio to discriminate dehydration was assessed using area under the receiver operating characteristic curve (auc) and the sensitivity and specificity of ivc-to-ao ratio was calculated for three cutoffs ( . , . , . ). calculation of auc was repeated after adjusting for age and sex. results: patients were enrolled, ( %) of whom had a cds of or higher. median age was (interquartile range - ) months, and ( %) were female. the ivcto-ao ratio showed an unadjusted auc of . ( % ci . - . ) and adjusted auc of . ( % ci . - . ). for a cutoff of . sensitivity was % ( % ci %- %) and specificity % ( % ci %- %); for a cutoff of . sensitivity was % ( % ci %- %) and specificity % ( % ci %- %); for a cutoff of . sensitivity was % ( % ci %- %) and specificity % ( % ci %- %). conclusion: the ability of the ivc-to-ao ratio to discriminate dehydration in young pediatric ed patients was modest and the cutoff of . was neither sensitive nor specific. background: while early cardiac computed tomographic angiography (ccta) could be more effective to manage emergency department (ed) patients with acute chest pain and intermediate (> %) risk of acute coronary syndrome (acs) than current management strategies, it also could result in increased testing, cost, and radiation exposure. objectives: the purpose of the study was to determine whether incorporation of ccta early in the ed evaluation process leads to more efficient management and earlier discharge than usual care in patients with acute chest pain at intermediate risk for acs. methods: randomized comparative effectiveness trial enrolling patients between - years of age without known cad, presenting to the ed with chest pain but without ischemic ecg changes or elevated initial troponin and require further risk stratification for decision making, at nine us sites. patients are being randomized to either ccta as the first diagnostic test or to usual care, which could include no testing or functional testing such as exercise ecg, stress spect, and stress echo following serial biomarkers. test results were provided to physicians but management in neither arm was driven by a study protocol. data on time, diagnostic testing, and cost of index hospitalization, and the following days are being collected. the primary endpoint is length of hospital stay (los). the trial is powered to allow for detection of a difference in los of . hours between competing strategies with % power assuming that % of projected los values are true. secondary endpoints are cumulative radiation exposure, and cost of competing strategies. tertiary endpoints are institutional, caregiver, and patient characteristics associated with primary and secondary outcomes. rate of missed acs within days is the safety endpoint. results: as of november st, , of patients have been enrolled (mean age: ± , . % female, acs rate . %). the anticipated completion of the last patient visit is / / and the database will be locked in early march . we will present the results of the primary, secondary, and some tertiary endpoints for the entire cohort. conclusion: romicat ii will provide rigorous data on whether incorporation of ccta early in the ed evaluation process leads to more efficient management and triage than usual care in patients with acute chest pain at intermediate risk for acs. (originally submitted as a ''late-breaker.'') meta background: many studies have documented higher rates of advanced radiography utilization across u.s. emergency departments (eds) in recent years, with an associated decrease in diagnostic yield (positive tests / total tests). provider-to-provider variability in diagnostic yield has not been well studied, nor have the factors that may explain these differences in clinical practice. objectives: we assessed the physician-level predictors of diagnostic yield using advanced radiography to diagnose pulmonary embolus (pe) in the ed, including demographics and d-dimer ordering rates. methods: we conducted a retrospective chart review of all ed patients who had a ct chest or v/q scan ordered to rule out pe from / to / in four hospitals in the medstar health system. attending physicians were included in the study if they had ordered or more scans over the study period. the result of each ct and vq scan was recorded as positive, negative, or indeterminate, and the identity of the ordering physician was also recorded. data on provider sex, residency type (em or other), and year of residency completion were collected. each provider's positive diagnostic yield was calculated, and logistic regression analysis was done to assess correlation between positive scans and provider characteristics. results: during the study period, , scans ( , cts and , v/qs) were ordered by providers. the physicians were an average of . years from residency, % were female, and % were em-trained. diagnostic yield varied significantly among physicians (p < . ), and ranged from % to %. the median diagnostic yield was . % (iqr . %- . %). the use of d-dimer by provider also varied significantly from % to % (p < . ). the odds of a positive test were significantly lower among providers less than years out of residency graduation (or . , ci . - . ) after controlling for provider sex, type of residency training, d-dimer use, and total number of scans ordered. conclusion: we found significant provider variability in diagnostic yield for pe and use of d-dimer in this study population, with % of providers having diagnostic yield less than or equal to . %. providers who were more recently graduated from residency appear to have a lower diagnostic yield, suggesting a more conservative approach in this group. background: the literature reports that anticoagulation increases the risk of mortality in patients presenting to emergency departments (ed) with head trauma (ht). it has been suggested that such patients should be treated in a protocolized fashion, including ct within minutes, and anticipatory preparation of ffp before ct results are available. there are significant logistical and financial implications associated with implementation of such a protocol. objectives: our primary objective was to determine the effect of anticoagulant therapy on the risk of intracranial hemorrhage (ich) in elderly patients presenting to our urban community hospital following bunt head injury. methods: this was a retrospective chart review study of ht patients > years of age presenting to our ed over a -month period. charts reviewed were identified using our electronic medical record via chief complaints and icd- codes and cross referencing with written ct logs. research assistants underwent review of at least % of their contributing data to validate reliability. we collected information regarding use of warfarin, clopidogrel, and aspirin and ct findings of ich. using univariate logistic regression, we calculated odds ratios (or) for ich with % ci. results: we identified elderly ht patients. the mean age of our population was , ( . %) admitted to using anticoagulant therapy, and % were on antiplatelet drugs. ( . %) of the cohort had icb, patients required neurosurgical intervention, and had transfusion of blood products. of the non-anticoagulated patients, ( . %) were found to have ich, half of those ( ) , and mir- ) were measured using real-time quantitative pcr from serum drawn at enrollment. il- , il- , and tnf-a were measured using a bio-plex suspension system. baseline characteristics, il- , il- , tnf-a and micrornas were compared using one way anova or fisher exact test, as appropriate. correlations between mirnas and sofa scores, il- , il- , and tnf-a were determined using spearman's rank. a logistic regression model was constructed using in-hospital mortality as the dependent variable and mirnas as the independent variables of interest. bonferroni adjustments were made for multiple comparisons. results: of patients, were controls, had sepsis, and had septic shock. we found no difference in serum mir- a or mir- between cohorts, and found no association between these micrornas and either inflammatory markers or sofa score. mir- demonstrated a significant correlation with sofa score (q = . , p = . ), il- (q = . , p = . ), but not il- or tnf-a (p = . , p = . ). logistic regression demonstrated mir- to be associated with mortality, even after adjusting for sofa score (p = . ). conclusion: mir- a or mir- failed to demonstrate any diagnostic or prognostic ability in this cohort. mir- was associated with inflammation, increasing severity of illness, and mortality, and may represent a novel prognostic marker for diagnosis and prognosis of sepsis. objectives: to examine the association between emergency physician recognition of sirs and sepsis and subsequent treatment of septic patients. methods: a retrospective cohort study of all-age patient medical records with positive blood cultures drawn in the emergency department from / - / at a level i trauma center. patient parameters were reviewed including vital signs, mental status, imaging, and laboratory data. criteria for sirs, sepsis, severe sepsis, and septic shock were applied according to established guidelines for pediatrics and adults. these data were compared to physician differential diagnosis documentation. the mann-whitney test was used to compare time to antibiotic administration and total volume of fluid resuscitation between two groups of patients: those with recognized sepsis and those with unrecognized sepsis. results: sirs criteria were present in / reviewed cases. sepsis criteria were identified in / cases and considered in the differential diagnosis in / septic patients. severe sepsis was present in / cases and septic shock was present in / cases. the sepsis -hour resuscitation bundle was completed in the emergency department in cases of severe sepsis or septic shock. patients who met sepsis criteria and were recognized by the ed physician had a median time to antibiotics of minutes (iqr: - ) and a median ivf of ml (iqr: - ). the patients who met sepsis criteria but went unrecognized in the documentation had a median time to antibiotics of minutes (iqr: - ) and median volume of fluid resuscitation of ml (iqr: . median time to antibiotics and median volume of fluid resuscitation differed significantly between recognized and unrecognized septic patients (p = . and p = . , respectively). conclusion: emergency physicians correctly identify and treat infection in most cases, but frequently do not document sirs and sepsis. lack of documentation of sepsis in the differential diagnosis is associated with increased time to antibiotic delivery and a smaller total volume of fluid administration, which may explain poor sepsis bundle compliance in the emergency department. background: severe sepsis is a common clinical syndrome with substantial human and financial impact. in the first consensus definition of sepsis was published. subsequent epidemiologic estimates were collected using administrative data, but ongoing discrepancies in the definition of severe sepsis led to large differences in estimates. objectives: we seek to describe the variations in incidence and mortality of severe sepsis in the us using four methods of database abstraction. methods: using a nationally representative sample, four previously published methods (angus, martin, dombrovskiy, wang) were used to gather cases of severe sepsis over a -year period ( ) ( ) ( ) ( ) ( ) ( ) . in addition, the use of new icd- sepsis codes was compared to previous methods. our main outcome measure was annual national incidence and in-hospital mortality of severe sepsis. results: the average annual incidence varied by as much as . fold depending on method used and ranged from , ( / , population) to , , ( , / , ) using the methods of dombrovskiy and wang, respectively. average annual increase in the incidence of severe sepsis was similar ( . - . %) across all methods. total mortality mirrored the increase in incidence over the -year period ( background: radiation exposure from medical imaging has been the subject of many major journal articles, as well as the topic of mainstream media. some estimate that one-third of all ct scans are not medically justified. it is important for practitioners ordering these scans to be knowledgeable of currently discussed risks. objectives: to compare the knowledge, opinions, and practice patterns of three groups of providers in regards to cts in the ed. methods: an anonymous electronic survey was sent to all residents, physician assistants, and attending physicians in emergency medicine (em), surgery, and internal medicine (im) at a single academic tertiary care referral level i trauma center with an annual ed volume of over , visits. the survey was pilot tested and validated. all data were analyzed using the pearson's chi-square test. results: there was a response rate of % ( / ). data from surgery respondents were excluded due to a low response rate. in comparison to im, em respondents correctly equated one abdominal ct to between and chest x-rays, reported receiving formal training regarding the risks of radiation from cts, believe that excessive medical imaging is associated with an increased lifetime risk of cancer, and routinely discuss the risks of ct imaging with stable patients more often (see table ). particular patient factors influence whether radiation risks are discussed with patients by % in each specialty (see table ). before ordering an abdominal ct in a stable patient, im providers routinely review the patient's medical imaging history less often than em providers surveyed. overall, % of respondents felt that ordering an abdominal ct in a stable ed patient is a clinical decision that should be discussed with the patient, but should not require consent. conclusion: compared with im, em practitioners report greater awareness of the risks of radiation from cts and discuss risks with patients more often. they also review patients' imaging history more often and take this, as well as patients' age, into account when ordering cts. these results indicate a need for improved education for both em and im providers in regards to the risks of radiation from ct imaging. background: in nebraska, % of emergency departments have annual visits less than , , and the predominance are in rural settings. general practitioners working in rural emergency departments have reported low confidence in several emergency medicine skills. current staffing patterns include using midlevels as the primary provider with non-emergency medicine trained physicians as back-up. lightly-embalmed cadaver labs are used for resident's procedural training. objectives: to describe the effect of a lightlyembalmed cadaver workshop on physician assistants' (pa) reported level of confidence in selected emergency medicine procedures. methods: an emergency medicine procedure lab was offered at the nebraska association of physician assistants annual conference. each lab consisted of a -hour hands-on session teaching endotracheal intubation techniques, tube thoracostomy, intraosseous access, and arthrocentesis of the knee, shoulder, ankle, and wrist to pas. irb-approved surveys were distributed pre-lab and a post-lab survey was distributed after lab completion. baseline demographic experience was collected. pre-and post-lab procedural confidence was rated on a six-point likert scale ( - ) with representing no confidence. the wilcoxon signed-rank test was use to calculate p values. results: pas participated in the course. all completed a pre-and post-lab assessment. no pa had done any one procedure more than times in their career. pre-lab modes of confidence level were £ for each procedure. post-lab modes were > for each procedure except arthrocentesis of the ankle and wrist. however, post lab assessments of procedural confidence significantly improved for all procedures with p values < . . conclusion: midlevel providers' level of confidence improved for emergent procedures after completion of a procedure lab using lightly-embalmed cadavers. a mobile cadaver lab would be beneficial to train rural providers with minimal experience. background: use of automated external defibrillators (aed) improves survival in out-of-hospital cardiopulmonary arrest (ohca). since , the american heart association has recommended that individuals one year of age or older who sustain ohca have an aed applied. little is known about how often this occurs and what factors are associated with aed use in the pediatric population. objectives: our objective was to describe aed use in the pediatric population and to assess predictors of aed use when compared to adult patients. methods: we conducted a secondary analysis of prospectively collected data from u.s. cities that participate in the cardiac arrest registry to enhance survival (cares). patients were included if they had a documented resuscitation attempt from october , through december , and were ‡ year old. patients were considered pediatric if they were less than years old. aed use included application by laypersons and first responders. hierarchical multivariable logistic regression analysis was used to estimate the associations between age and aed use. results: there were , ohcas included in this analysis, of which ( . %) occurred in pediatric patients. overall aed use in the final sample was , , with , ( . %) total survivors. aeds were applied less often in pediatric patients ( . %, % ci: . %- . % vs . %, % ci: . %- . %). within the pediatric population, only . % of patients with a shockable rhythm had an aed used. in all pediatric patients, regardless of presenting rhythm, aed use demonstrated a statistically significant increase in return of spontaneous circulation (aed used . %, % ci: . - . vs aed not used . %, % ci: . - . , p < . ), although there was no significant increase in survival to hospital discharge (aed used . %; aed not used . %; p = . ). in the adjusted model, pediatric age was independently associated with failure to use an aed (or . , % ci: . - . ) as was female sex (or . , % ci: . - . ). patients who had a public arrest (or . , % ci: . - . ) or one that was witnessed by a bystander (or . . %: ci . - . ) were also predictive of aed use. conclusion: pediatric patients who experience ohca are less likely to have an aed used. continued education of first responders and the lay public to increase aed use in this population is necessary. does implementation of a therapeutic hypothermia protocol improve survival and neurologic outcomes in all comatose survivors of sudden cardiac arrest? ken will, michael nelson, abishek vedavalli, renaud gueret, john bailitz cook county (stroger), chicago, il background: the american heart association (aha) currently recommends therapeutic hypothermia (th) for out of hospital comatose survivors of sudden cardiac arrest (cssca) with an initial rhythm of ventricular fibrillation (vf). based on currently limited data, the aha further recommends that physicians consider th for cssca, from both the out and inpatient settings, with an initial non-vf rhythm. objectives: investigate whether a th protocol improves both survival and neurologic outcomes for cssca, for out and inpatients, with any initial rhythm, in comparison to outcomes previously reported in literature prior to th. methods: we conducted a prospective observational study of cssca between august and may whose care included th. the study enrolled eligible consecutive cssca survivors, from both out and inpatient settings with any initial arrest rhythm. primary endpoints included survival to hospital discharge and neurologic outcomes, stratified by sca location, and by initial arrest rhythm. results: overall, of eligible patients, ( %, % ci - %) survived to discharge, ( %, % ci - %) with at least a good neurologic outcome. twelve were out and were inpatients. among the outpatients, ( %, % ci - %) survived to discharge, ( %, % ci - %) with at least a good neurologic outcome. among the inpatients, ( %, % ci - ) survived to discharge, ( %, % ci - %) with at least a good neurologic outcome. by initial rhythm, patients had an initial rhythm of vf/t and non-vf/t. among the patients with an initial rhythm of vf/t, ( %, ci - %) survived to discharge, all with at least a good outcome, including out and inpatients. among the patients with an initial rhythm of non-vf/t, ( %, ci - %) survived to discharge, ( %, ci - %) with at least a good neurologic outcome, including out and inpatients. conclusion: our preliminary data initially suggest that local implementation of a th protocol improves survival and neurologic outcomes for cssca, for out and inpatients, with any initial rhythm, in comparison to outcomes previously reported in literature prior to th. subsequent research will include comparison to local historical controls, additional data from other regional th centers, as well as comparison of different cooling methods. protocolized background: therapeutic hypothermia (th) has been shown to improve the neurologic recovery of cardiac arrest patients who experience return of spontaneous circulation (rosc). it remains unclear as to how earlier cooling and treatment optimization influence outcomes. objectives: to evaluate the effects of a protocolized use of early sedation and paralysis on cooling optimization and clinical outcomes in survivors of cardiac arrest. methods: a -year ( - ), pre-post intervention study of patients with rosc after cardiac arrest treated with th was performed. those patients treated with a standardized order set which lacked a uniform sedation and paralytic order were included in the pre-intervention group, and those with a standardized order set which included a uniform sedation and paralytic order were included in the post-intervention group. patient demographics, initial and discharge glasgow coma scale (gcs) scores, resuscitation details, cooling time variables, severity of illness as measured by the apache ii score, discharge disposition, functional status, and days to death were collected and analyzed using student's t-tests, man-whitney u tests, and the log-rank test. results: patients treated with th after rosc were included, with patients in the pre-intervention group and in the post-intervention group. the average time to goal temperature ( °c) was minutes (pre-intervention) and minutes (post-intervention) (p = . ). a -hour time target was achieved in . % of the patients (post-intervention) compared to . % in the pre-group (p = . ). twenty-eight day mortality was similar between groups ( . % and . %) though hospital length of stay ( days pre-and days post-intervention) and discharge gcs ( preand -post-intervention) differed between cohorts. more post-intervention patients were discharged to home ( . %) compared to . % in the pre-intervention group. conclusion: protocolized use of sedation and paralysis improved time to goal temperature achievement. these improved th time targets were associated with improved neuroprotection, gcs recovery, and disposition outcome. standardized sedation and paralysis appears to be a useful adjunct in induced th. background: ct is increasingly used to assess children with signs and symptoms of acute appendicitis (aa) though concerns regarding long-term risk of exposure to ionizing radiation have generated interest in methods to identify children at low risk. objectives: we sought to derive a clinical decision rule (cdr) of a minimum set of commonly used signs and symptoms from prior studies to predict which children with acute abdominal pain have a low likelihood of aa and compared it to physician clinical impression (pci). methods: we prospectively analyzed subjects aged to years in u.s. emergency departments with abdominal pain plus signs and symptoms suspicious for aa within the prior hours. subjects were assessed by study staff unaware of their diagnosis for clinical attributes drawn from published appendicitis scoring systems and physicians responsible for physical examination estimated the probability of aa based on pci prior to their medical disposition. based on medical record entry rate, frequently used cdr attributes were evaluated using recursive partitioning and logistic regression to select the best minimum set capable of discriminating subjects with and without aa. subjects were followed to determine whether imaging was used and use was tabulated by both pci and the cdr to assess their ability to identify patients who did or did not benefit based on diagnosis. results: this cohort had a . % prevalence ( / subjects) of aa. we derived a cdr based on the absence of two out of three of the following attributes: abdominal tenderness, pain migration, and rigidity/ guarding had a sensitivity of . % ( % ci: . - . ), specificity of . % ( % ci: . - . ), npv of . % ( % ci: . - . ), and negative likelihood ratio of . ( % ci: . - . ). the pci set at aa < % pre-test probability had a sensitivity of . % ( % ci: . - . ), specificity of . % ( % ci: . - . ), npv of . % ( % ci: . - . ), and negative likelihood ratio of . ( % ci: . - . ). the methods each classified % of the patients as low risk for aa. our cdr identified . % ( / ) of low risk subjects who received ct but being aa (-), could have been spared ct, while the pci identified . % ( / ). conclusion: compared to physician clinical impression, our clinical decision rule can identify more children at low risk for appendicitis who could be managed more conservatively with careful observation and avoidance of ct. negative background: abdominal pain is the most common complaint in the ed and appendicitis is the most common indication for emergency surgery. a clinical decision rule (cdr) identifying abdominal pain patients at a low risk for appendicitis could lead to a significant reduction in ct scans and could have a significant public health impact. the alvarado score is one of the most widely applied cdrs for suspected appendicitis, and a low modified alvarado score (less than ) is sometimes used to rule out acute appendicitis. the modified alvarado score has not been prospectively validated in ed patients with suspected appendicitis. objectives: we sought to prospectively evaluate the negative predictive value of a low modified alvarado score (mas) in ed patients with suspected appendicitis. we hypothesized that a low mas (less than ) would have a sufficiently high npv (> %) to rule out acute appendicitis. methods: we enrolled patients greater than or equal to years old who were suspected of having appendicitis (listed as one of the top three diagnosis by the treating physician before ancillary testing) as part of a prospective cohort study in two urban academic eds from august to april . elements of the mas and the final diagnosis were recorded on a standard data form for each subject. the sensitivity, specificity, negative predictive value (npv), and positive predictive value (ppv) were calculated with % ci for a low mas and final diagnosis of appendicitis. background: evaluating children for appendicitis is difficult and strategies have been sought to improve the precision of the diagnosis. computed tomography is now widely used but remains controversial due to the large dose of ionizing radiation and risk of subsequent radiation-induced malignancy. objectives: we sought to identify a biomarker panel for use in ruling out pediatric acute appendicitis as a means of reducing exposure to ionizing radiation. methods: we prospectively enrolled subjects aged to years presenting in u.s. emergency departments with abdominal pain and other signs and symptoms suspicious for acute appendicitis within the prior hours. subjects were assessed by study staff unaware of their diagnosis for clinical attributes drawn from appendicitis scoring systems and blood samples were analyzed for cbc differential and candidate proteins. based on discharge diagnosis or post-surgical pathology, the cohort exhibited a . % prevalence ( / subjects) of appendicitis. clinical attributes and biomarker values were evaluated using principal component, recursive partitioning, and logistic regression to select the combination that best discriminated between those subjects with and without disease. mathematical combination of three inflammation-related markers in a panel comprised of myeloid-related protein / complex (mrp), c-reactive protein (crp), and white blood cell count (wbc) provided optimal discrimination. results: this panel exhibited a sensitivity of % ( % ci, - %), a specificity of % ( % ci, - %), and a negative predictive value of % ( % ci, - %) in this cohort. the observed performance was then verified by testing the panel against a pediatric subset drawn from an independent cohort of all ages enrolled in an earlier study. in this cohort, the panel exhibited a sensitivity of % ( % ci, - %), a specificity of % ( % ci, - %), and a negative predictive value of % ( % ci, - %). conclusion: appyscore is highly predictive of the absence of acute appendicitis in these two cohorts. if these results are confirmed by a prospective evaluation currently underway, the appyscore panel may be useful to classify pediatric patients presenting to the emergency department with signs and symptoms suggestive of, or consistent with, acute appendicitis and thereby sparing many patients ionizing radiation. background: there are no current studies on the tracking of emergency department (ed) patient dispersal when a major ed closes. this study demonstrates a novel way to track where patients sought emergency care following the closure of saint vincent's catholic medical center (svcmc) in manhattan by using de-identified data from a health information exchange, the new york clinical information exchange (nyclix). nyclix matches patients who have visited multiple sites using their demographic information. on april , , svcmc officially stopped providing emergency and outpatient services. we report the patterns in which patients from svcmc visited other sites within nyclix. objectives: we hypothesize that patients often seek emergency care based on geography when a hospital closes. methods: a retrospective pre-and post-closure analysis was performed of svcmc patients visiting other hospital sites. the pre-closure study dates were january , -march , . the post closure study dates were may , -july , . a svcmc patient was defined as a patient with any svcmc encounter prior to its closure. using de-identified aggregate count data, we calculated the average number of visits per week by svcmc patients at each site (hospital a-h). we ran a paired t-test to compare the pre-and post-closure averages by site. the following specifications were used to write the database queries: of patients who had one or more prior visits to svcmc for each day within the study return the following: a. eid: a unique and meaningless proprietary id generated within the nyclix master patient index (mpi). b. age: thru the age of . persons over were listed as '' + '' c. ethnicity/race d. type of visit: emergency e. location of visit: specific nyclix site. results: nearby hospitals within miles saw the highest number of increased ed visits after svcmc closed. this increase was seen until about miles. hospitals > miles away did not see any significant changes in ed visits. see table. conclusion: when a hospital and its ed close down, patients seem to seek emergency care at the nearest hospital based on geography. other factors may include the patient's primary doctor, availabilities of outpatient specialty clinics, insurance contracts, or preference of ambulance transports. this study is limited by the inclusion of data from only the eight hospitals participating in nyclix at the time of the svcmc closure. upstream methods: data were collected on all ed ems arrivals from the metro calgary (population . million) area to its three urban adult hospitals. the study phases consisted of the months from february to october (pre-ocp) compared against the same months in (post-ocp). data from the ems operational database and the regional emergency department information system (redis) database were linked. the primary analysis examined the change in ems offload delay defined as the time from ems triage arrival until patient transfer to an ed bed. a secondary analysis evaluated variability in ems offload delay between receiving eds. conclusion: implementation of a regional overcapacity protocol to reduce ed crowding was associated with an important reduction in ems offload delay, suggesting that policies that target hospital processes have bearing on ems operations. variability in offload delay improvements is likely due to site-specific issues, and the gains in efficiency correlate inversely with acuity. methods: a pre-post intervention study was conducted in the ed of an adult university teaching hospital in montreal (annual visits = ). the raz unit (intervention), created to offload the acu of the main ed, started operating in january, . using a split flow management strategy, patients were directed to the raz unit based on patient acuity level (ctas code and certain code ), likelihood to be discharged within hours, and not requiring an ed bed for continued care. data were collected weekdays from : to : for months (september -december ) (pre-raz) and for . months (february -march ) (post-raz). in the acu of the main ed, research assistants observed and recorded cubicle access time, and nurse and physician assessment times. databases were used to extract socio-demographics, ambulance arrival, triage code, chief complaint, triage and registration time, length of stay, and ed occupancy. background: telephone follow-up after discharge from the ed is useful for treatment and quality assurance purposes. ed follow-up studies frequently do not achieve high (i.e. ‡ %) completion rates. objectives: to determine the influence of different factors on the telephone follow-up rate of ed patients. we hypothesized that with a rigorous follow-up system we could achieve a high follow-up rate in a socioeconomically diverse study population. methods: research assistants (ras) prospectively enrolled adult ed patients discharged with a medication prescription between november , and september , from one of three eds affiliated with one health care system: (a) academic level i trauma center, (b) community teaching affiliate, and (c) community hospital. patients unable to provide informed consent, non-english speaking, or previously enrolled were excluded. ras interviewed subjects prior to ed discharge and conducted a telephone follow-up interview week later. follow-up procedures were standardized (e.g. number of calls per day, times to place calls, obtaining alternative numbers) and each subject's follow-up status was monitored and updated daily through a shared, web-based data system. subjects who completed follow-up were mailed a $ gift card. we examined the influence of patient (age, sex, race, insurance, income, marital status, usual major activity, education, literacy level, health status), clinical (acuity, discharge diagnosis, ed length of stay, site), and procedural factors (number and type of phone numbers received from subjects, offering two gift cards for difficult to reach subjects) on the odds of successful followup using multivariate logistic regression. results: of the , enrolled, % were white, % were covered by medicaid or uninsured, and % reported an annual household income of <$ , . % completed telephone follow-up with % completing on the first attempt. the table displays the factors associated with successful follow-up. in addition to patient demographics and lower acuity, obtaining a cell phone or multiple phone numbers as well as offering two gift cards to a small number of subjects increased the odds of successful follow-up. conclusion: with a rigorous follow-up system and a small monetary incentive, a high telephone follow-up rate is achievable one week after an ed visit. methods: an interrupted time-series design was used to evaluate the study question. data regarding adherence with the following pneumonia core measures were collected pre-and post-implementation of the enhanced decision-support tool: blood cultures prior to antibiotic, antibiotic within hours of arrival, appropriate antibiotic selection, and mean time to antibiotic administration. prescribing clinicians were educated on the use of the decision-support tool at departmental meetings and via direct feedback on their cases. results: during the -month study period, complete data were collected for patients diagnosed with cap: in the pre-implementation phase and post-implementation. the mean time to antibiotic administration decreased by approximately one minute from the pre-to post-implementation phase, a change that was not statistically significant (p = . ). the proportion of patients receiving blood cultures prior to antibiotics improved significantly (p < . ) as did the proportion of patients receiving antibiotics within hours of ed arrival (p = . ). a significant improvement in appropriate antibiotic selection was noted with % of patients experiencing appropriate selection in the post-phase, p = . . use of the available support tool increased throughout the study period, v = . , df = , p < . . all improvements were maintained months following the study intervention. conclusion: in this academic ed, introduction of an enhanced electronic clinical decision support tool significantly improved adherence to cms pneumonia core measures. the proportion of patients receiving blood cultures prior to antibiotics, antibiotics within hours, and appropriate antibiotics all improved significantly after the introduction of an enhanced electronic clinical decision support tool. background: emergency medicine (em) residency graduates need to pass both the written qualifying exam and oral certification exam as the final benchmark to achieve board certification. the purpose of this project is to obtain information about the exam preparation habits of recent em graduates to allow current residents to make informed decisions about their individual preparation for the abem written qualifying and oral certification exams. objectives: the study sought to determine the amount of residency and individual preparation, to determine the extent of the use of various board review products, and to elicit evaluations of the various board review products used for the abem qualifying and certification exams. methods: design: an online survey instrument was used to ask respondents questions about residency preparation and individual preparation habits, as well as the types of board review products used in preparing for the em boards. participants: as greater than % of all em graduates are emra members, an online survey was sent to all emra members who have graduated for the past three years. observations: descriptive statistics of types of preparation, types of resources, time, and quantitative and qualitative ratings for the various board preparation products were obtained from respondents. results: a total of respondents spent an average of . weeks and hours per week preparing for the written qualifying exam and spent an average of weeks and . hours per week preparing for the oral certification exam. in preparing for the written qualification exam, % used a preparation textbook with % using more than one textbook and % using a board preparation course. in preparing for the oral qualifying exam, % used a preparation textbook while % used a preparation course. sixty-seven percent of respondents reported that their residency programs had a formalized written qualifying exam preparation curriculum of which % was centered on the annual in-training exam. eight-five percent of residency programs had a formalized oral certification exam preparation. respondents reported spending on average $ preparing for the qualifying exam and $ for the certification exam. conclusion: em residents spend significant amounts of time and money and make use of a wide range of residency and commercially available resources in preparing for the abem qualifying and certification exams. background: communication and professionalism skills are essential for em residents but are not wellmeasured by selection processes. the multiple mini-interview (mmi) uses multiple, short structured contacts to measure these skills. it predicts medical school success better than the interview and application. its acceptability and utility in em residency selection is unknown. objectives: we theorized that the mmi would provide novel information and be acceptable to participants. methods: interns from three programs in the first month of training completed an eight-station mmi developed to focus on em topics. pre-and post-surveys assessed reactions using five-point scales. mmi scores were compared to application data. results: em grades correlated with mmi performance (f( . ) = : , p < . ) with honors students having higher mmi summary scores. higher third year clerkship grades trended to higher mmi performance means, although not significantly. mmi performance did not correlate with a match desirability rating and did not predict other individual components of the application including usmle step or usmle step . participants preferred a traditional interview (mean difference = . , p < . ). a mixed format was preferred over a pure mmi (mean difference = . , p < . ). preference for a mixed format was similar to a traditional interview. mmi performance did not significantly correlate with preference for the mmi; however, there was a trend for higher performance to associate with higher preference (r = . , t( ) = . , n.s.) performance was not associated with preference for a mix of interview methods (r = . , t( ) = . , n.s.). conclusion: while the mmi alone was viewed less favorably than a traditional interview, participants were receptive to a mixed methods interview. the mmi appears to measure skills important in successful completion of an em clerkship and thus likely em residency. future work will determine whether mmi performance correlates with clinical performance during residency. background: the annual american board of emergency medicine (abem) in-training exam is a tool to assess resident progress and knowledge. when the new york-presbyterian (nyp) em residency program started in , the exam was not emphasized and resident performance was lower than expected. a course was implemented to improve residency-wide scores despite previous em literature failing to exhibit improvements with residency-sponsored in-training exam interventions. objectives: to evaluate the effect of a comprehensive, multi-faceted course on residency-wide in-training exam performance. methods: the nyp em residency program, associated with cornell and columbia medical schools, has a year format with - residents per year. an intensive -week in-training exam preparation program was instituted outside of the required weekly residency conferences. the program included lectures, pre-tests, high-yield study sheets, and remediation programs. lectures were interactive, utilizing an audience response system, and consisted of core lectures ( - . hours) and three review sessions. residents with previous in-training exam difficulty were counseled on designing their own study programs. the effect on intraining exam scores was measured by comparing each resident's score to the national mean for their postgraduate year (pgy). scores before and after course implementation were evaluated by repeat measures regression modeling. overall residency performance was evaluated by comparing residency average to the national average each year and by tracking abem national written examination pass rates. results: resident performance improved following course implementation. following the course's introduction, the odds of a resident beating the national mean increased by . ( % ci . - . ) and the percentage of residents exceeding the national mean for their pgy year increased by % ( % ci %- %). following course introduction, the overall residency mean score has outperformed the national exam mean annually and the first-time abem written exam board pass rate has been %. conclusion: a multi-faceted in-training exam program centered around a -week course markedly improved overall residency performance on the in-training exam. limitations: this was a before and after evaluation as randomizing residents to receive the course was not logistically or ethically feasible. . years of practice. among the nonresidency trained, non-boarded em physicians, the percentage of individuals with board actions against them was significantly higher ( . % vs. . %, % ci for difference of . % = . to . %), but the incidence of actions was not significant ( . vs. . events/ years of practice, % ci for difference of . / = ) / to + / ), but the power to detect a difference was %. conclusion: in this study population, em-trained physicians had significantly fewer total state medical board disciplinary actions against them than non-em trained physicians, but when adjusted for years of practice (incidence), the difference was not significantly different at the % confidence level. the study was limited by low power to detect a difference in incidence. objectives: we chose pain documentation as a long term project for quality improvement in our ems system. our objectives were to enhance the quality of pain assessment, to reduce patient suffering and pain through improved pain management, to improve pain assessment documentation, to improve capture of initial and repeat pain scales, and to improve the rate of pain medication. this study addressed the aim of improving pain assessment documentation. methods: this was a quasi-experiment looking at paramedic documentation of the pqrst mnemonic and pain scales. our intervention consisted of mandatory training on the importance and necessity of pain assessment and treatment. in addition to classroom training, we used rapid cycle individual feedback and public posting of pain documentation rates (with unique ids) for individual feedback. the categories of chief complaint studied were abdominal pain, blunt injury, burn, chest pain, headache, non-traumatic body pain, and penetrating injury. we compared the pain documentation rates in the months prior to intervention, the months of intervention, and months post intervention. using repeated-measures anova, we compared rates of paramedic documentation over time. results: our ems system transported patients during the study period, of whom were for painful conditions in the defined chief complaint categories. there were paramedics studied, of whom had complete data. documentation increased from of painful cases ( . %) in qtr to of painful cases ( . %) in qtr . the trend toward increased rates of pain documentation over the three quarters was strongly significant (p < . ). paramedics were significantly more likely to document pain scales and pqrst assessments over the course of the study with the highest rates of documentation compliance in the final -month period. conclusion: a focused intervention of education and individual feedback through classroom training, one on one training, and public posting improves paramedic documentation rates of perceived patient pain. background: emergency medical services (ems) systems are vital in the identification, assessment, and treatment of trauma, stroke, myocardial infarction, and sepsis and improving early recognition, resuscitation, and transport to adequate medical facilities. ems personnel provide similar first-line care for patients with syncope, performing critical actions such as initial assessment and treatment as well as gathering key details of the event. objectives: to characterize emergency department patients with syncope receiving initial care by ems and their role as initial providers. methods: we prospectively enrolled patients over years of age who presented with syncope or near syncope to a tertiary care ed with , annual patient visits from june to june . we compared patient age, sex, comorbidities, and -day cardiopulmonary adverse outcomes (defined as myocardial infarction, pulmonary embolism, significant cardiac arrhythmia, and major cardiovascular procedure) between ems and non-ems patients. descriptive statistics, two-sided ttests, and chi-square testing were used as appropriate. results: of the patients enrolled, ( . %) arrived by ambulance. the most common complaint in patients transported by ems was fainting ( . %) or dizziness ( . %); syncope was reported in ( . %). compared to non-ems patients, those who arrived by ambulance were older (mean age (sd) . ( . ), vs. . ( . ) years, p = . ). there were no differences in the proportion of patients with hypertension ( . % vs . %, p = . ), coronary artery disease ( . % vs . %, p = . ), diabetes mellitus ( . % vs . %, p = . ), or congestive heart failure ( . % vs . %, p = . ). sixtynine ( . %) patients experienced a cardiopulmonary event within days. twenty-eight ( . %) patients who arrived by ambulance and ( . %) non-ems patients had a subsequent cardiopulmonary adverse event (rr . , %ci . - . ) within days. the table tabulates interventions provided by ems prior to ed arrival. conclusion: ems providers care for more than one third of ed syncope patients and often perform key interventions. ems systems offer opportunities for advancing diagnosis, treatment, and risk stratification in syncope patients. background: abdominal pain is the most common reason for visiting an emergency department (ed), and abdominopelvic computed tomography (apct) use has increased dramatically over the past decade. despite this, there has been no significant change in rates of admission or diagnosis of surgical conditions. objectives: to assess whether an electronic accountability tool affects apct ordering in ed patients with abdominal or flank pain. we hypothesized that implementation of an accountability tool would decrease apct ordering in these patients. methods: before and after study design using an electronic medical record at an urban academic ed from jul-nov , with the electronic accountability tool implemented in oct for any apct order. inclusion criteria: age >= years, non-pregnant, and chief complaint or triage pain location of abdominal or flank pain. starting oct th , , resident attempts to order apct triggered an electronic accountability tool which only allowed the order to proceed if approved by the ed attending physician. the attending was prompted to enter the primary and secondary diagnoses indicating apct, agreement with need for ct and, if no agreement, who was requesting this ct (admitting or consulting physician), and their pretest probability ( - ) of the primary diagnosis. patients were placed into two groups: those who presented prior to (pre) and after (post) the deployment of the accountability tool. background: there has been a paradigm shift in the diagnostic work-up for suspected appendicitis. edbased staged protocols call for the use of ultrasound prior to ct scanning because of its lack of radiation, and the morbidity related to contrast. a barrier to implementation is the lack of / availability of ultrasound. objectives: to evaluate the impact of the implementation of ed performed appendix ultrasounds (apus) on ct utilization in the staged workup for appendicitis in the emergency department. methods: we performed a quasi-experimental, before/ after study. we compared data from the first months of , before the availability of ed performed apus, with the same interval in after introduction of ed apus. we excluded patients who had appendectomies for reasons other than appendicitis or had been diagnosed prior to arrival. no patient identifiers were included in the analysis and the study was approved by the hospital irb. we report the following descriptive statistics (percentages, sensitivities, and absolute utilization changes conclusion: implementation of an ed apus in the staging work up of appendicitis was associated with a significant reduction in overall ct utilization in the ed. objectives: this study aims to evaluate ed patients' knowledge of radiation exposure from ct and mri scans as well as the long-term risk of developing cancer. we hypothesize that ed patients will have a poor understanding of the risks, and will not know the difference between ct and mri. methods: design -this was a cross-sectional survey study of adult, english-speaking patients at two eds from / / - / / . setting -one location was a tertiary care center with an annual ed census of , patient visits and the other was a community hospital with annual ed census of , patient visits. obser-vations -the survey consisted of six questions evaluating patients' understanding of radiation exposure from ct and mri as well as long-term consequences of radiation exposure. patients were then asked their age, sex, race, highest level of education, annual household income, and whether they considered themselves health care professionals. results: there were participants in this study, (of , total) from the academic center and (of , total) from the community hospital during the study period. overall, only % ( % ci - %) of participants understood the radiation risks associated with ct scanning. % ( % ci - %) of patients believed that an abdominal ct had the same or less radiation as a chest x-ray. % ( % ci - %) believed that there was an increased risk of developing cancer from repeated abdominal cts. only % ( % ci - %) of patients knew that mri scans had less radiation than ct. % ( % ci - %) either didn't know or believed that repeated mris were associated with an increased risk of developing cancer. higher educational level, household income, and identification as a health care professional all were associated with correct responses, but even within these groups, a majority gave incorrect responses. conclusion: in general, ed patients do not understand the radiation risks associated with advanced imaging modalities. we need to educate these patients so that they can make informed decisions about their own health care. background: homelessness has been associated with many poor health outcomes and frequent ed utilization. it has been shown that frequent use of the ed in any given year is not a strong predictor of subsequent use. identifying a group of patients who are chronic high users of the ed could help guide intervention. objectives: the purpose of this study is to identify if homelessness is associated with chronic ed utilization. methods: a retrospective chart review was accomplished looking at the records of the most frequently seen patients in the ed for each year from - at a large, urban academic hospital with an annual volume of , . patients' visit dates, chief complaints, dispositions, and housing status were reviewed. homelessness was defined by self-report at registration. patients were categorized according to their ed utilization with those seen > times in at least three of the five years of the study identified as chronic high utilizers; and those who visited the ed > times in at least three of the five years of the study were identified as chronic ultra-high utilizers. descriptive statistics with confidence intervals were calculated, and comparisons were made using non-parametric tests. results: during the -year study period, , unique patients were seen, of whom . % patients were homeless. patients were identified as frequent users. there were patients who presented on the top utilizer lists from multiple years. ( %, %ci - ) patients were identified as homeless. patients were seen > times in at least three of the years and ( %, - ) were homeless. patients were seen > times in at least three of the years and ( %, - ) were homeless. our facility has a % admission rate; however, non homeless chronic ultra-high utilizers had admission rates of % and homeless chronic ultra-high utilizers were admitted %. conclusion: chronic ultra-high utilizers of our ed are disproportionately homeless and present with lower severity of illness. these patients may prove to be a cost-effective group to house or otherwise involve with aggressive case management. the debate over homeless housing programs and case management solutions can be sharpened by better defining the groups who would most benefit and who represent the greatest potential saving for the health system. background: the prevalence of obese patients presenting to our emergency department (ed) is %: obese patients present in disproportionate number compared to the general population (us rate = %). in spite of this, there is a disconnect in patients' perceptions of weight and health: many patients underestimate their weight and report a key barrier to weight loss is patient-provider communications; such discussions have proven to be highly effective in smoking, drug, and alcohol cessation, an important initial step toward promoting wellness. information about patient provider communication is essential for designing and implementing emergency department (ed) based interventions to help increase patient awareness about weightrelated medical issues and provide counseling for weight reduction. objectives: we assessed patients' perceptions about obesity as disease and patient communication with their providers through two questions: do you believe your present weight is damaging to your health? has a doctor or other health professional every told you that you are overweight? methods: a descriptive cross-sectional study was performed in an academic tertiary care ed. a randomized sample of patients (every fifth) presenting to the ed (n = ) was enrolled. pregnant patients, patients who were medically unstable, cognitively impaired, or who were unable or unwilling to provide informed consent were excluded. percentages of ''yes'' and ''no'' are reported for each question based on patient bmi, ethnicity, sex, and the number of comorbid conditions. regression analysis was used to determine differences in responses between subgroups. results: among overweight/obese, white/black patients, . % do not feel their weight is damaging to their health and . % reported they have not been told by a doctor they are overweight. of individuals who have been told by a doctor they were overweight, . % still believe their present weight is not damaging to their health. of individuals who have not been told by a doctor they were overweight, . % believe their present weight is damaging to their health. differences in race and age were not found. p values < . for all results. conclusion: our data point toward a disconnect regarding patients' perceptions of health and weight. timely education about the burden of obesity may lead to a decrease in its overall prevalence. (originally submitted as a ''late-breaker.'') objectives: to examine the attitudes and expectations of patients admitted for inpatient care following an emergency department visit. methods: a descriptive study was done by surveying a voluntary sample of adult patients (n = ) admitted to the hospital from the emergency department in one urban teaching hospital in the midwest. a short, ninequestion survey was developed to assess patient attitudes and expectations towards hiv testing, consent, and requirements. analyses consisted of descriptive statistics, correlations, and chi-square analyses. results: the majority of patients report that hiv testing should be a routine part of health care screening ( . %) and that the hospital should routinely test admitted patients for hiv ( . %). despite these overall positive attitudes towards hiv testing, the data also suggest that patients have strong attitudes towards consent requirements with % acknowledging that hiv testing requires special consent and % reporting that separate consent should be required. the data also showed a statistically significant difference in the proportion of patients who believed that hiv testing is a part of routine health care screening by race (v = . , df = , p = . ). conclusion: patients attitudes and expectations towards routine hiv testing are consistent with the cdc recommendations. emergency departments are an ideal setting to initiate hiv testing and the findings suggest that patients expect hospital policies outline procedures for obtaining consent and screening all patients who are admitted to the hospital from the ed. results: the analysis revealed a ''hot spot'', a cluster of counties ( . %) with high ca rates adjacent to counties with high ca rates, located across the southeastern us (p < . ). within these counties, the average ca rate was % higher than the national average. a ''cool spot'', a cluster of counties ( . %) with low rates, was located across the midwest (p < . ). in this cool spot the average ca rate was % lower than the national average. figures and show us adjusted rates and spatial autocorrelation of ca deaths, respectively. conclusion: we identify geographic disparities in ca mortality and describe the cardiac arrest belt in the southeastern us. a limitation of this analysis was the use of icd- codes to identify cardiac arrest deaths; however, no other national data exist. an improved understanding of the drivers of this variability is essential to targeted prevention and treatment strategies, especially given the recent emphasis on development of cardiac resuscitation centers and cardiac arrest systems of care. an understanding of the relation between population density, cardiac arrest count, and cardiac arrest rate will be essential to the design of an optimized cardiac arrest system. we defined ed utilization during the past months as non-users ( visits), infrequent users ( - visits), frequent users ( - visits), and super-frequent users ( ‡ visits). we compared demographic data, socioeconomic status, health conditions, and access to care between these ed utilization groups. results: overall, super-frequent use was reported by . % of u.s. adults, frequent use by %, and infrequent ed use by %. higher ed utilization was associated with increased self-reported fair to poor health ( % for super-frequent, % for frequent, % for infrequent, % for non-ed users). frequent ed users were also more likely to be impoverished, with % of superfrequent, % of frequent, % of infrequent, and % of non-ed users reporting a poverty-income ratio < . adults with higher ed utilization were more likely to report the ed as the place they usually go when sick ( % for super-frequent, % for frequent, % for infrequent, . % for non-ed users). they also reported greater outpatient resource utilization, with % of super-frequent, % of frequent, % of infrequent, and % of non-ed users reporting ‡ outpatient visits/year. frequent ed users were also more likely than non-ed users to be covered by medicaid ( % for super-frequent, % for frequent, % for infrequent, % for non-ed users). conclusion: frequent ed users were a vulnerable population with lower socioeconomic status, poor overall health, and high outpatient resource utilization. interventions designed to divert frequent users from the ed should also focus on chronic disease management and access to outpatient services, rather than focusing solely on limiting ed utilization. objectives: we explored factors associated with specialty provider willingness to provide urgent appointments to children insured by medicaid/chip. methods: as part of a mixed method study of child access to specialty care by insurance status, we conducted semi-structured qualitative interviews with a purposive sample of specialists and primary care physicians (pcps) in cook county, il. interviews were conducted from april to september , until theme saturation was reached. resultant transcripts and notes were entered into atlas.ti and analyzed using an iterative coding process to identify patterns of responses in the data, ensure reliability, examine discrepancies, and achieve consensus through content analysis. results: themes that emerged indicate that pcps face considerable barriers getting publicly insured patients into specialty care and use the ed to facilitate this process. ''if i send them to the emergency room, i'm bypassing a number of problems. i'm fully aware that i'm crowding the emergency room.'' specialty physicians reported that decisions to refuse or limit the number of patients with medicaid/chip are due to economic strain or direct pressure from their institutions ''in the last budget revision, we were [told], 'you are losing money, so you need to improve your patient mix'''. in specialty practices with limited medicaid/chip appointment slots, factors associated with appointment success included: high acuity or complexity, personal request from or an informal economic relationship with the pcp, geography, and patient hardship. ''if it's a really desperate situation and they can't find anybody else, i will make an exception''. specialists also acknowledged that ''patients who can't get an appointment go to the er and then i am obligated to see them if they're in the system.'' conclusion: these exploratory findings suggest that a critical linkage exists between hospital eds and affiliated specialty clinics. as health systems restructure, there is an opportunity for eds to play a more explicit role in improving care coordination and access to specialty care. albert amini, erynne a. faucett, john m. watt, richard amini, john c. sakles, asad e. patanwala university of arizona, tucson, az background: trauma patients commonly receive etomidate and rocuronium for rapid sequence intubation (rsi) in the ed. due to the long duration of action of rocuronium and short duration of action of etomidate, these patients require prompt initiation of sedatives after rsi. this prevents the potential of patient awareness under pharmacological paralysis, which could be a terrifying experience. objectives: the purpose of this study was to evaluate the effect of the presence of a pharmacist during traumatic resuscitations in the ed on the initiation of sedatives and analgesics after rsi. we hypothesized that pharmacists would decrease the time to provision of sedation and analgesia. methods: this was an observational, retrospective cohort study conducted in a tertiary, academic ed that is a level i trauma center. consecutive adult trauma patients who received rocuronium in the ed for rsi were included during two time periods: / / to / / (pre-phase -no pharmacy services in the ed) and / / to / / (post-phase -pharmacy services in the ed). since the pharmacist could not respond to all traumas in the post-phase, this was further categorized based on whether the pharmacist was present or absent at the trauma resuscitation. data collected included patient demographics, baseline injury data, and medications used. the median time from rsi to initiation of sedatives and analgesics was compared between the pre-phase group (group ), post-phase pharmacist absent group (group ), and post-phase pharmacist present group (group ) using the kruskal-wallis test. results: a total of patients were included in the study (group = , group = , and group = ). median age was , . , and . years in groups , , and , respectively (p = . ). there were no other differences between groups with regard to demographics, mechanism of injury, presence of traumatic brain injury, glasgow coma scale score, vital signs, ed length of stay, or mortality. median time between rsi and post-intubation sedative use was , , and minutes in groups , and , respectively (p < . ). median time between rsi and post-intubation analgesia use was , , and minutes in groups , , and , respectively (p < . ). the presence of a pharmacist during trauma resuscitations decreases time to provision of sedation and analgesia after rsi. background: outpatient antibiotics are frequently prescribed from the ed, and limited health literacy may affect compliance with recommended treatments. objectives: among patients stratified by health literacy level, multimodality discharge instructions will improve compliance with outpatient antibiotic therapy and follow-up recommendations. methods: this was a prospective randomized trial that included consenting patients discharged with outpatient antibiotics from an urban county ed with an annual census of , . patients unable to receive text messages or voicemails were excluded. health literacy was assessed using a validated health literacy assessment, the newest vital sign (nvs). patients were randomized to a discharge instruction modality: ) usual care, typed and verbal medication and case-specific instructions; ) usual care plus text messaged instructions sent to the patient's cell phone; or ) usual care plus voicemailed instructions sent to the patient's cell phone. antibiotic pick-up was verified with the patient's pharmacy at hours. patients were called at days to determine antibiotic compliance. z-tests were used to compare -hour antibiotic pickup and patient-reported compliance across instructional modality and nvs score groups. results: patients were included ( % female, median age , range months to years); were excluded. % had an nvs score of - , % - , and % - . the proportion of prescriptions filled at hours varied significantly across nvs score groups; self-reported medication compliance at days revealed no difference across different instructional modalities nor nvs scores (table ) . conclusion: in this sample of urban ed patients, hour prescription pickup varied significantly by validated health literacy score, but not by instruction delivery modality. in this sample, patients with lower health literacy are at risk of not filling their outpatient antibiotics in a timely fashion. has been developed, validated, and utilized to study the processes of care involved in successful care transitions from inpatient to outpatient settings, but has not been utilized in the ed. objectives: we hypothesized that the ctm- could be successfully implemented in the ed without differential item difficulty by age, sex, education, or race; and would be associated with measures of quality of care and likelihood of following physician recommendations. methods: a descriptive study design based on exit surveys was used to measure ctm- scores and likelihood of following treatment recommendations. surveys were administered to a daily cross-sectional sample of all patients leaving the ed between a- a by research assistants in an urban academic ed setting for weeks in november . we report means and standard deviations, and analysis of variance to identify differences in ctm- scores for those who planned and did not plan to follow ed recommendations. results: surveys were completed; patients were ± years old, % black, % female, % with at least some college education, and % were admitted. average ctm- score was . ± . (range - ). scores were not associated with sex (p = . ), race (p = . ), or education level (p = . ). lower ctm scores were associated with increasing age (p = . ), patient perceptions that the ed team was less likely to use words that they understood, listen carefully to them, inspire their confidence and trust, or encourage them to ask questions (all p < . ). those who reported they were ''very likely'' to follow ed treatment had an average score of ± , while those who were ''unlikely'' or ''very unlikely'' to follow ed treatment plans had an average score ± (p = . ). conclusion: the ctm- performs well in the ed and exhibited only differential item difficulty by age; there was no significant difference by race, sex, or education level. furthermore, it is highly associated with likelihood of following physician recommendations. future studies will focus on ctm- scores ability to discriminate between patients who did or did not experience a subsequent ed visit or rehospitalization. age and race were found to be significant predictors of the race pathway. regression of the data by race revealed blacks (or . : ci . - . ; p < . ), hispanics (or . : ci . - . ; p = . ), and asians (or . : ci . - . ; p = . ), were more likely to enter the race cohort than were whites; however, much of this discrepancy is accounted for by age. the mean age of minority patients was years, while white patients were older at years (p = . ). conclusion: in a diverse demographic population we found that racial minorities were presenting at younger ages for chest pain and were more likely to receive cardiac testing at bedside than their white counterparts; and hence, were selected to a lower level of care (nonmonitored unit background: expanding insurance coverage is designed to improve access to primary care and reduce use of emergency services. whether expanding coverage achieves this is of paramount importance as the united states prepares for the affordable care act. objectives: we examined ed and outpatient department use after the state children's health insurance program (schip) coverage expansion, focusing on adolescents (a major target group for schip) versus young adults (not targeted). we hypothesized that coverage would increase use of outpatient services and emergency department services would decrease. methods: using the national ambulatory medical care survey and the national hospital ambulatory medical care survey, we analyzed years - as baseline and then compared use patterns in - after schip launch. primary outcomes were populationadjusted annual visits to ed versus non-emergency outpatient settings. interrupted time-series were performed on use rates to ed and outpatient departments between adolescents ( - years old) and young adults ( - years old) in the pre-schip and schip periods. outpatient-to-ed ratios were calculated and compared across time periods. results: the mean number of outpatient adolescent visits increased by visits per persons ( % ci, - ), while there was no statistically significant increase in young adult outpatient visits across time periods. there was no statistically significant change in the mean number of adolescent ed visits across time periods, while young adult ed use increased by visits per persons ( % ci, - ). the adolescent outpatient-to-ed ratio increased by . ( % ci, . - . ), while the young adults ratio decreased by . across time periods ( % ci, ) . to ) . ). conclusion: since schip, adolescent non-ed outpatient visits increased while ed visits remained unchanged. in comparison to young adults, expanding insurance coverage to adolescents improved access to health care services and suggests a shift to non-ed settings. as an observational study we are unable to control for secular trends during this time period. also as an ecological study we are unable to examine individual variation. expanding insurance through the affordable care act of will likely increase use of outpatient services but may not decrease emergency department volumes. background: cancer patients are receiving a greater proportion of their care on an outpatient basis. the effect of this change in oncology care patterns on ed utilization is poorly understood. objectives: to examine the characteristics of ed utilization by adult cancer patients. methods: between july and march , all new adult cancer patients referred to a tertiary care cancer centre were recruited into a study examining psychological distress. these patients were followed prospectively until september . the collected data were linked to administrative data from three tertiary care eds. variables evaluated in this study included basic we have previously shown that reducing non-value-added activities through the application of the lean process improvement methodology improves patient satisfaction, physician productivity and emergency department length of stay. objectives: in this investigation, we tested the hypothesis that non-value-added activities reduce physician job satisfaction. methods: to test this hypothesis, we conducted timemotion studies on attending emergency physicians working in an academic setting and categorized their activities into value-added (time in room with patient, time discussing cases and educating medical learners, time in room with patient and learner), necessary non-valueadded activities (charting, sign out, looking up labs), and unnecessary non-value-added activities (looking for things, looking for people, on the phone). the physicians were then surveyed using a -point likert scale to determine their relative satisfaction with each of the individual tasks ( worst part of day, best part of day). results: physicians spent % of their shift performing value-added work, % of their shift performing necessary non-value-added activities, and % of their shift performing unnecessary non-value-added activities (waste). weighted physician satisfaction (satisfaction x [percent time spent performing the activity / percent time engaged in activity category]) was highest when the physician was performing value-added work ( . ) compared to performing either necessary non-valueadded work ( . ) or waste ( . ). conclusion: the attending physicians we studied spent the majority of their time performing non-value-added activities, which were associated with lower satisfaction. application of process improvement techniques such as lean, which focus on reducing non-value-added work, may improve emergency physician job satisfaction. background: rocuronium and succinylcholine are the most commonly used paralytics for rapid sequence intubation (rsi) in the ed. after rsi, patients need sustained sedation while they are mechanically ventilated. however, the longer duration of action of rocuronium may influence subsequent sedation dosing, while the patient is therapeutically paralyzed. objectives: we hypothesized that patients who receive rocuronium would be more likely to receive lower doses of post-rsi sedation compared to patients who receive succinylcholine. methods: this was an observational, retrospective cohort study conducted in a tertiary, academic ed. consecutive adult patients, who received rsi using etomidate for induction of sedation between / / to / / , were included. patients were then categorized based on whether they received rocuronium or succinylcholine for paralysis. the dosing of post-rsi sedative infusions was compared at , , , and minutes after initiation between the two groups using the wilcoxon rank-sum test. results: a total of patients were included in the final analysis (rocuronium = , succinylcholine = ). mean age was and years in the rocuronium and succinylcholine groups, respectively (p = . ). there were no other baseline differences between groups with regard to demographics, reason for intubation, stroke, traumatic brain injury, glasgow coma scale score, pain scores, or vital signs. in the overall cohort, . % (n = ) of patients were given a sedative infusion or bolus in the ed. most patients were initiated on propofol (n = ) or midazolam (n = ) infusions. median propofol infusion rates at , , , and minutes were , , . , and mcg/kg/min in the rocuronium group and , , , and mcg/kg/ min in succinylcholine group, respectively. the difference was statistically significant at (p < . ) and (p = . ) minutes. median midazolam infusion rates at , , , and minutes were , , , and mg/hour in the rocuronium group and , , , and . mg/hour in succinylcholine group, respectively. the difference was statistically significant at (p = . ) and (p = . ) minutes. conclusion: patients who receive rocuronium are more likely to receive lower doses of sedative infusions post-rsi due to sustained therapeutic paralysis. this may put them at risk for being awake under paralysis. what is the impact of the implementation of an there was a difference in presenting pain (p < . ), stress (p < . ), and anxiety (p < . ) among patients that received an opioid in the ed. there was a difference in presenting pain (p < . ) for patients discharged with an opioid prescription, but not for stress (p = . ) or anxiety (p = . ). conclusion: patient-reported pain, stress, and anxiety are higher among patients who received an opiate in the ed than in those who did not, but only pain is higher among patients who received a discharge prescription for an opioid. methods: this was a prospective, randomized crossover study on the use of gvl and dl by incoming pediatric interns prior to advanced life support training. at the start of the study, the interns received a didactic session and expert modeling of the use of both devices for intubation. two scenarios were used: ( ) normal intubation with a standard airway and ( ) difficult intubation with tongue edema and pharyngeal swelling. interns then intubated laerdal simbaby in each scenario with both gvl and dl for a total of four randomized intubation scenarios. primary outcomes included time to successful intubation and the rate of successful intubation. the interns also rated their satisfaction with the devices using a visual analog scale ( - ) and chose their preferred device for their next intubation. results: interns were included in this study. in the normal airway scenario, there were no differences in the mean time for intubation with gvl or dl ( . ± . vs . ± . seconds, p = ns) or the number of interns who performed successful intubation ( vs , p = ns). in the difficult airway scenario, the interns took longer to intubate with gvl than dl ( . ± . vs . ± . seconds, p = . ), but there were no differences in the number of successful intubations ( vs , p = ns). interns rated their satisfaction higher for gvl than dl ( . ± . vs . ± . , p = . ) and gvl was chosen as the preferred device for their next intubation by a majority of the interns ( / , %). conclusion: for novice clinicians, gvl does not improve the time to intubation or intubation success objectives: to determine the time to intubation, the number of attempts, and the occurrence of hypoxia, in patients intubated with a c-mac device versus those intubated using a standard laryngoscope. methods: randomized controlled trial using exception from informed consent that included patients undergoing endotracheal intubation with a standard laryngoscope at an urban level i trauma center. eligible patients were randomized to undergo intubation using the c-mac or standard laryngoscopy. standard laryngoscopy was performed using a c-mac device laryngoscope with the video output obstructed to ensure equivalent laryngoscope blades in the two groups. data were collected by a trained research assistant at the patient's bedside and video review by the investigators. the number of attempts made, the initial and lowest oxygen saturation (spo ), and the total time until the intubation was successful was recorded. hypoxia was defined as an oxygen saturation < %. data were compared with wilcoxon rank sum and chi-square tests. results: thirty-eight patients were enrolled, ( % male, median age , range to , median spo %, range to ) in the standard laryngoscopy group and ( % male, median age , range to , median spo . %, range to ) in the c-mac group. the median number of attempts for standard laryngoscopy was , range to , and for c-mac was , range to (p = . ). the median time to intubation for the standard laryngoscopy group was seconds (range to ) and for the c-mac group was seconds (range to )(p = . ). hypoxia was detected in / ( %) in the standard laryngoscopy group and / ( %) in the c-mac group (p = . ). the median decrease in oxygen saturation during the attempt was . % (range % to %) for the standard laryngoscopy group and . % (range % to %) for the c-mac group. conclusion: we did not detect a difference in number of attempts, the occurrence of hypoxia, or the diagnosis of aspiration pneumonia between standard laryngoscopy and the c-mac. the time to successful intubation was shorter for patients intubated with the c-mac. the c-mac device appears to be superior to standard laryngoscopy for emergent endotracheal intubation. (originally submitted as a ''late-breaker.'') the background: aspiration pneumonia is a complication of endotracheal intubation that may be related to the difficulty of the airway procedure. objectives: to determine the association of the device used, the time to intubation, the number of attempts to intubate, and the occurrence of hypoxia with the subsequent development of aspiration pneumonia. methods: this was a prospective observational study of patients undergoing endotracheal intubation by emergency physicians at an urban level i trauma center conducted from / / until / / . the device used on the initial attempt to intubate was at the discretion of the treating physician. data were collected by a trained research assistant at the patient's bedside. the device used, the number of attempts made to intubate, the lowest oxygen saturation during the attempt, and the total time until intubation was successfully accomplished were recorded. patient's medical records were reviewed for the subsequent diagnosis of aspiration pneumonia. hypoxia was defined as an oxygen saturation < %. data were analyzed using multinomial logistic regression and odds ratios (or). results: patients were enrolled; ( %) subsequently developed aspiration pneumonia. were intubated with a standard laryngoscope (sl), using the c-mac, with an intubating laryngeal mask, and with nasotracheal intubation (ni) (or . , % ci = . - . ). comparison of individual devices versus sl did not show an association by device type. the median number of attempts for patients with aspiration pneumonia was , range to , and for those without was , range to (or . , %ci = . - . ). the median time to intubation for patients who developed aspiration pneumonia was seconds (range to ) and for those who did not was seconds (range to )(or . , %ci = . - . ). hypoxia during intubation was detected in / ( %) in the aspiration pneumonia group and / ( %) in the no aspiration pneumonia group (or . , % ci = . - . ). conclusion: there was not an association between the device used, the number of attempts, the time to intubation, or the occurrence of hypoxia during the intubation, and the subsequent occurrence of aspiration pneumonia. background: japanese census data estimate that million, or nearly % of the overall population, will be over age by the year . similar trends are apparent throughout the developed world. although increased patient age affects airway management, comprehensive information in emergency airway management for the elderly is lacking. objectives: we sought to characterize emergency department (ed) airway management for the elderly in japan including success rate, and major adverse events using a large multi-center registry. methods: design and setting: we conducted a multicenter prospective observational study using the japanese emergency airway network (jean) registry of eds at academic and community hospitals in japan between and inclusive. data fields included ed characteristics, patient and operator demographics, methods of airway management, number of attempts, success rate, and adverse events. participants: patient inclusion criteria were all adult patients who underwent emergent tracheal intubation in the ed. primary analysis: patients were divided to into two groups defined as follows: to years old and over years old. we describe primary success rates and major adverse events using simple descriptive statistics. categorical data are reported as proportions and % confidence intervals (cis). results: the database recorded patients (capture rate %) and met the inclusion criteria. of patients, patients were to years old ( %) and were over years old ( %). the older group had a significantly higher success rate at first attempt intubation ( / ; . %, % ci . - . %) compared with the younger group ( / ; . %, % ci . - . %). the older group had similar major adverse event rates ( / ; . %, % ci . - . %) compared with the younger group ( / ; . %, % ci . - . %). (see table ) background: the degree to which a patient's report of pain is associated with changes in blood pressure, heart rate, and respiratory rate is not known. objectives: to determine to what degree a standardized painful stimulus effects a change in systolic blood pressure (sbp), diastolic blood pressure (dbp), heart rate (hr), or respiratory rate (rr), and compare changes in vital signs between patients based on pain severity. methods: prospective observational study of healthy human volunteers. subjects had their sbp, dbp, hr, and rr measured prior to pain exposure, immediately after, and minutes after. pain exposure consisted of subjects placing their hand in a bath of degree water for seconds. the bath was divided into two sections; the larger half was the reservoir of cooled water monitored to be degrees, the other half filled from constant overflow over the divider. water drained from this section into the cooling unit and was then pumped up into the base of the reservoir through a diffusion grid. subjects completed a mm visual analog scale (vas) representing their perceived pain during the exposure and graded their pain as minimal, moderate or severe. data were compared using % confidence intervals. results: subjects were enrolled, mean pain vas mm, range to , reported mild pain, moderate pain, and severe pain. the percent change from baseline in vital signs during the exposure and minutes after are presented in the table. conclusion: there was a wide variety in reported pain among subjects exposed to a standard painful stimulus. there was a larger change in heart rate during the exposure among subjects who described a standardized painful exposure as moderate than in those who described it as severe. the small observed changes in blood pressure and respiratory rate seen during the exposure did not differ by pain report or persist after minutes. background: vital signs are often used to validate intensity of pain. however, few studies have looked at the capacity of vital signs to estimate pain intensity, particularly in patients with a diagnosis that a majority of physicians would agree produce significant pain in the ed. objectives: to determine the association between pain intensity and vital signs in consecutive ed patients and in a sub-group of patients with diagnosis known to cause significant pain. methods: we performed a post-hoc analysis of prospectively acquired data in a cohort study done in an urban teaching hospital with computerized triage and nurses records. we included all consecutive ed adult patients ( ‡ years old), who had any level of pain intensity measured during triage, from march to november . the primary outcome was the mean heart rate, systolic and diastolic blood pressure for every pain intensity level from to on a verbal numerical scale. our secondary outcomes where the same but limited to patients with the following diagnosis: fracture, dislocation, and renal colic. we performed descriptive statistics, one-way and two-way anovas when appropriate. results: during our study period, , patients ‡ years old where triaged with a pain intensity of at least / and had a diagnosis known to cause significant pain. . % of patients were female, with a mean pain intensity of . / , mean age of . years (± . ), and . % were ‡ years old. there was a statistically significant difference (p < . ) in mean heart rate, systolic and diastolic blood pressure for each level of pain intensity, ex: difference between / and / for mean heart rate was . beats per minutes, for systolic pressure was . mmhg and for diastolic . mmhg. results are similar for painful diagnosis: difference for mean heart rate was . beats per minutes, for systolic pressure was . mmhg and diastolic . mmhg. however, these differences are not clinically significant. conclusion: although our study is a post hoc analysis, pain intensity, heart rate, systolic and diastolic pressures during triage are usually reliable data and a prospective study would likely produce the same result. these vital signs cannot be used to estimate or validate pain intensity in the emergency department. % had a positive urine drug screen. logistic multivariate regressions analyses revealed the following factors to be significantly associated with the risk of having an abnormal head ct: association with seizure (p = . ); length of time of loss of consciousness, ranging from none to - min to > min (p = . ); alteration of consciousness (p = . ); post-traumatic amnesia (p = . ); alcohol intake prior to injury (p = , ); and initial ed gcs (p = . ). conclusion: in an emergency department cohort of patients with traumatic brain injury, symptoms including loss of or alteration in consciousness, seizure, post traumatic amnesia, and alcohol intake appear to be significantly associated with abnormal findings on head ct. these clinical findings on presentation may be useful in helping triage head injury patients in a busy emergency department, and can further define the need for urgent or emergent imaging in patients without clearly apparent injuries. background: the etiology of neurogenic shock is classically attributed to diminished peripheral vascular resistance (pvr) secondary to loss of sympathetic outflow to the peripheral vasculature. however, the sympathetic nervous system also controls other key elements of the cardiovascular system such as the heart and capacitance vessels and disruptions in their function could complicate the hemodynamic presentation. objectives: we sought to systematically examine the hemodynamic profiles of a series of trauma patients with neurogenic shock. methods: consecutive trauma patients with documented spinal cord injury complicated by clinical shock were enrolled. hemodynamic data including systolic and diastolic blood pressure, heart rate (hr), impedance-derived cardiac output, pre-ejection period (pep), left ventricular ejection time (lvet), and calculated systemic pvr were collected in the ed. data were normalized for body surface area and a validated integrated computer model of human physiology (guyton model) was used to analyze and categorize the hemodynamic profiles based on etiology of the hypotension using a systems analysis. correlation between markers of sympathetic outflow (hr, pep, lvet) and shock etiology category was examined. results: of patients with traumatic neurogenic shock, the etiology of shock was decrease in pvr in ( %; % ci to %), loss of vascular capacitance in ( %; to %), and mixed peripheral resistance and capacitance responsible in ( %; to %). the markers of sympathetic outflow had no correlation to any of the elements in the patients' hemodynamic profiles. conclusion: neurogenic shock is often considered to have a specific well-characterized pathophysiology. results from this study suggest that neurogenic shock can have multiple mechanistic etiologies and represents a spectrum of hemodynamic profiles. this understanding is important for the treatment decisions made in the management of these patients. -year ( - ) , pre-post intervention study of trauma patients requiring massive blood transfusion was performed. we divided the population into two cohorts: a pre-protocol group (pre) which included trauma patients receiving mbt not aided by a protocol, and a post-protocol group (post) who underwent mbt via the mbtp. patient demographics, hour blood component totals, timing of blood component delivery, trauma injury severity score (iss), initial glasgow coma scale (gcs) score, trauma mechanism, and patient mortality data were collected and analyzed using fisher's exact tests, student's t-tests, and mann-whitney u tests. results: fifty-two patients were included for study. median times to delivery of first products were reduced for prbcs ( minutes), ffp ( minutes), and platelets ( minutes) between the pre and post cohorts. median time to delivery of any subsequent blood product was significantly reduced ( minutes) in the post cohort (p = . ). the median number of blood products delivered was increased by . units for prbcs, units for ffp, . units for platelets, and unit for cryoprecipitate after implementation of mbtp. the percentage of patients receiving higher blood product ratios (> : ) was reduced between the pre and post cohorts for prbc to ffp ( % reduction) and prbc to platelet ratio groups ( % reduction). despite improved transfusion timing and ratios, we found no significant difference in mortality (p = . ) between pre and post cohorts when we adjusted for injury severity. conclusion: protocolized delivery of massive blood transfusion might reduce time to product availability and delivery, though it is unclear how this affects patient mortality in all us trauma centers. background: burns are common injuries that can result in significant scarring leading to poor function and disfigurement. unlike mechanical injuries, burns often progress both in depth and size over the first few days after injury, possibly due to inflammation and oxidative stress. a major gap in the field of burns is the lack of an effective therapy that reduces burn injury progression. objectives: since mesenchymal stem cells (msc) have been shown to improve healing in several injury models, we hypothesized that species-specific msc would reduce injury progression in a rat comb burn model. methods: using a gm brass comb preheated to degrees celsius, we created four rectangular burns, separated by three unburned interspaces on both sides of the backs of male sprague-dawley rats ( g). the interspaces represented the ischemic zones surround-ing the central necrotic core. left untreated, most of these interspaces become necrotic. in an attempt to reduce burn injury progression, rats were randomized to tail vein injections of ml rat-specific msc cells/ml (n = ) or normal saline (n = ) minutes after injury. tracking of the stem cells was attempted by injecting several rats with quantum dot-labeled msc. results: by four days post-injury, all of the interspaces in the control rats ( / , %) became necrotic while in the experimental group, / ( %) of the interspaces became necrotic (fisher's exact test; p < . ). at days, the percentage of the unburned interspaces that became necrotic in the msc treated group was significantly less than in the control group ( % vs. %, p < . ). we were unable to identify any quantum dot labeled msc in the injured skin. no adverse reactions or wound infections were noted in rats injected with msc. conclusion: intravenous injection of rat msc reduced burn injury progression in a rat comb burn model. although basic demographics of bicyclists in accidents have been described, there is a paucity of data describing the street surface involved in accidents, and whether designated bicycle roadways offer protection. this lack of information limits informed attempts to change infrastructure in a way that will decrease morbidity and/or mortality of cyclists. objectives: to identify road surface types involved in pedal cyclist injuries and determine the relationship between injury severity and the use of designated bicycle roadways (dbr) versus non-designated roadways (ndr). we hypothesized that more severe injuries would happen at intersections regardless of dbr versus ndr. methods: this retrospective cohort study reviewed the trauma database from a level i trauma center in tucson, az. we identified all bicyclists in the database injured in accidents involving a motor vehicle from january , , through december , . the patients were then linked to a local government database that documents location (latitude/longitude) and direction of travel of the cyclist. seventy-eight total incidents were identified and categorized as occurring on a dbr versus ndr and occurring at an intersection versus not at an intersection. results: only one patient who arrived at the trauma center died. fifty-one of the accidents ( %) occurred on dbrs; % of accidents occurring on dbrs took place in intersections. conversely, % of accidents on ndrs occurred outside of intersections. the odds of an injury occurring at an intersection versus not at an intersection were . times higher ( % ci: . - . ) for dbrs compared to ndrs. the odds of a trauma being severe (admitted) versus not severe (discharged home) were . times higher ( % ci: . - . ) when a collision occurred not at an intersection versus at an intersection. conclusion: contrary to our hypothesis, in this study group severe injuries were more likely outside of an intersection. however, intersections on dbrs were identified as problematic as cyclists on a dbr were more likely to be injured in an intersection. future city planning could target improved cyclist safety in intersections. background: minor thoracic injury (mti) is frequent and a significant proportion will still have moderate to severe pain at days. there is a lack of risk factors to orient specific treatment at ed discharge. objectives: to determine risk factors of having pain ( ‡ / , on a numerical intensity pain score from to ) at days in a population of minor thoracic injury patients discharged from the ed. methods: a prospective multi-center cohort study was conducted in four canadian eds, from november to january . all consecutive patients, years and older, with mti (with or without rib fracture), a normal chest x-ray, and discharged from the ed were eligible. a standardized clinical and radiological evaluation was done at and weeks. standardized phone interviews were done at and days. pain evaluation occurred at five time points (ed visit, and weeks, and days). using a pain trajectory model (sas), we planned to identify groups with different pain evolution at days. the final model was based on the importance of difference in pain evolution, confidence intervals, and number of patients in each group. to judge the adequacy of the final model, we examined whether the posteriori probabilities (i.e., a participant's probability of belonging to a certain trajectory group) averaged at least % for each trajectory group. then using logistic multinomial regression and the low risk group of having pain as the control group, we identified significant predictors of patients in the moderate and high risk groups having pain at days. results: in our cohort of , patients, , had an evaluation at days. we identified three groups at low ( %), moderate ( . %), and high risk ( . %) of having pain ‡ / at days. using risk factor identified by univariate analysis, we created a model to identify patients at risk containing the following predictors: age ‡ years old, women, current smoker, two or more rib fractures, complaint of dyspnea, and saturation < % at initial visit. posteriori probabilities for low, moderate, and high risk were %, %, and %. conclusion: to our knowledge, this is the first study to identify potential risk factor for having pain at days after minor thoracic injury. these risk factors should be validated in a prospective study to guide specific treatment plan. the use of ultrasound to evaluate traumatic optic neuropathy benjamin burt, lisa montgomery, cynthia garza meissner, sanja plavsic-kupesic, nadah zafar ttuhsc -paul l foster school of medicine, el paso, tx background: whenever head trauma occurs, there is the possibility for a patient to have an optic nerve injury. the current method to evaluate optical nerve swelling is to look for proptosis. however, by the time proptosis presents, significant damage has already occurred. therefore, there is a need to establish a method to evaluate nerve injury prior to the development of proptosis. objectives: fundamental to understanding the pathophysiology of optic nerve injury and repair is an understanding of the optic nerve's temporal response to trauma including blood flow changes and vascular reactivity. the aim of our study was to assess the dependability and reproducibility of ultrasound techniques to sequence optic nerve healing and monitor the vascular response of the ophthalmic artery following an optic nerve crush. methods: the rat's orbit was imaged prior to and following a direct injury to the optic nerve, at hours and at days. d, d, and color doppler techniques were used to detect blood flow and the course of the ophthalmic artery and vein, to evaluate the course and diameter of the optic nerve, and to assess the extent of optic nerve trauma and swelling. the parameters used to evaluate healing over time were pulsatility and resistance indices of the ophthalmic artery. results: we have established baseline ultrasound measurements of the optic nerve diameter, normal resistance and pulsatility indices of the ophthalmic artery, and morphological assessment of the optic nerve in a rat model. longitudinal assessment of d and d ultrasound parameters were used to evaluate vascular response of the ophthalmic artery to optic nerve crush injury. we have developed a rat model system to study traumatic optic nerve injury. the main advantages of ultrasound are low cost, non-invasiveness, lack of ionizing radiation, and the potential to perform longitudinal studies. our preliminary data indicate that d and d color doppler ultrasound may be used for the evaluation of ophthalmic artery and total orbital perfusion following trauma. once baseline ultrasound and doppler measurements are defined there is the opportunity to translate the rat model to evaluate patients with head trauma who are at risk for optic nerve swelling and to assess the usefulness of treatment interventions. background: alcoholism is a chronic disease that affects an estimated . million american adults. a common presentation to the emergency department (ed) is a trauma patient with altered sensorium who is presumed to be alcohol intoxicated by the physicians based on their olfactory sense. often ed physicians may leave patients suspected of alcohol intoxication aside until the effects wear off, potentially missing major trauma as the source of confusion or disorientation. this practice often results in delays in diagnosing acute potentially life-threatening injuries in the patients with presumed alcohol intoxication. objectives: this study will determine the accuracy of physicians' olfactory sense for diagnosing alcohol intoxication. methods: patients suspected of major trauma in the ed underwent an evaluation by the examining physician for the odor of alcohol as well as other signs of intoxication. each patient had determination of blood alcohol level. alcohol intoxication was defined as a serum ethanol level ‡ mg/dl. data were reported as means with % confidence intervals ( % ci) or proportions with inter-quartile ranges (iqr %- %). results: one hundred and fifty one patients ( % males) were enrolled in the study, median age years (iqr - ). the median score for glasgow coma scale was . the level of training of examining physician was a median of pgy (iqr pgy -attending). prevalence of alcohol intoxication was % ( % ci: % to %). operating characteristics: physician assessment of alcohol intoxication, sensitivity % ( % ci: % to %), specificity % ( % ci: % to %), positive likelihood ratio . ( % ci: . to . ), negative likelihood ratio . ( % ci: . to . ), and accuracy % ( % ci: % to %). patients who were falsely suspected of being intoxicated were . % ( % ci: % to %). conclusion: although the physicians had a high degree of accuracy in identifying patients with alcohol intoxication based on their olfactory sense, they still falsely overestimated intoxication in a significant number of non-intoxicated trauma patients. the background: optimal methods for education and assessment in emergency and critical care ultrasound training for residents are not known. methods of assessment often rely on surrogate endpoints which do not assess the ability of the learner to perform the imaging and integrate the imaging into diagnostic and therapeutic decisions. we designed an educational strategy that combines asynchronous learning to teach imaging skills and interpretation with a standardized assessment tool using a novel ultrasound simulator to assess the learner's ability to acquire and interpret images in the setting of a standardized patient scenario. objectives: to assess the ability of emergency medicine and surgical residents to integrate and apply information and skills acquired in an asynchronous learning environment in order to identify pathology and prioritize relevant diagnoses using an advanced cardiac ultrasound simulator. methods: em r residents and r surgical residents completed an online focused training program in cardiac ultrasonography (iccu elearning, https:// www.caeiccu.com/lms). this consisted of approximately hours of intensive training in cardiac ultrasound. residents were then given cases with a patient scenario that lacked significant details that would suggest a specific diagnosis. the resident was then given a list of possible diagnoses and asked to rank the top five diagnoses in order of most likely to least likely. each resident (blinded to the pathology displayed by the simulator) then imaged using an ultrasound simulator. after imaging, the residents were given the same list of potential diagnoses, and asked to rank them again from - . results: overall, residents ranked the correct diagnosis in the top five significantly more times post-ultrasound than pre-ultrasound. additionally, the residents made the correct diagnosis significantly more times postultrasound than pre-ultrasound. similar patterns occur for congestive heart failure, pericardial effusion with tamponade, and pleural effusion. there was no significant difference pre-and post-ultrasound for pulmonary embolism and anterior infarction. conclusion: an asynchronous online learning program significantly improves the ability of emergency medicine and surgical residents to correctly prioritize the correct diagnosis after imaging with a standardized pathology imaging simulator. mark favot, jacob manteuffel, david amponsah henry ford hospital, detroit, mi background: em clerkships are often the only opportunity medical students have to spend a significant amount of time caring for patients in the ed. it is imperative that students gain exposure to as many of the various fields within em as possible during this time. if the exposure of medical students to ultrasound is left to the discretion of the supervising physicians, we feel that many students would complete an em clerkship with limited skills and knowledge in ultrasound. the majority of medical students receive no formal training in ultrasound during medical school and we believe that the em clerkship is an excellent opportunity to fill this educational gap. objectives: evaluate the usefulness and effectiveness of a focused ultrasound curriculum for medical students in an em clerkship at a large, urban, academic medical center. methods: prospective cohort study of fourth year medical students doing an em clerkship. as part of the clerkship requirements, the students have a portion of the curriculum dedicated to the fast exam and ultrasound-guided vascular access. at the end of the month they take a written test, and month later they are given a survey via e-mail regarding their ultrasound experience. em residents also completed the test to serve as a comparison group. all data analysis was done using sas . . scores were integers ranging between and . descriptive statistics are given as count, mean, standard deviation, median, minimum, and maximum for each group. due to non-gaussian nature of the data and small group sizes, a wilcoxon two-sample test was used to compare the distributions of scores between the groups. results: in the table, the distribution of scores was compared between the residents (controls) and the students (subjects). the mean and median scores of the student group were higher than those of the resident group. the difference in scores between the two groups was statistically significant (p = . ). conclusion: our data reveal that after completing an em clerkship with time devoted to learning ultrasound for the fast exam and vascular access, fourth year medical students are able to perform better than em residents on a written test. what remains to be determined is if their skills in image acquisition and in performance of ultrasound-guided vascular access procedures also exceed those of em residents. results: there were respondents (total response rate . %). compared to non-em students, students pursuing em ( students, . %) were more drawn to their specialty for work hour control (p < . ) and shorter residency length (p < . ). em students were less likely than non-em students to be drawn to their chosen specialty for future academic opportunities (p < . ). em students formed their mentorships by referral significantly more than non-em students (p < . ), though there was no statistical difference in quality of existing mentorships amongst students. of the students not currently and never formerly interested in em, the most common response ( . %) for why they did not choose em was the lack of a strong mentor in the field. conclusion: the results confirmed previous findings of lifestyle factors drawing students to em. future academic opportunities were less likely to draw students to em than students pursuing other specialties. lack of mentorship in the field was the most common reason given for why students did not consider em. given the lack of direct em exposure until late in the curriculum of most medical schools, mentorship may be particularly important for em and future study should focus on this area. background: misdiagnosis is a major public health problem. dizziness leads to million visits annually in the us, including . million to the emergency department (ed). despite extensive ed workups, diagnostic accuracy remains poor, with at least % of strokes missed in those presenting with dizziness. ed physicians need and want support, particularly in the best method for diagnosis. strong evidence now indicates the bedside oculomotor exam is the best method of differentiating central from peripheral causes of dizziness. objectives: after a vertigo day that includes instruction in head impulse testing, emergency medicine residents will feel comfortable discharging a patient with signs of vestibular neuritis and a positive head impulse test without ordering a ct scan. methods: post graduate year - emergency medicine residents participated in a four hour vertigo day. we developed a mixed cognitive and systems intervention with three components: an online game that began and ended the day, a didactic taught by dr. newman-toker, and a series of small group exercises. the small group sessions included the following: a question and answer session with the lecturer; vertigo special tests (cerebellar assessment, dix hall-pike, epley maneuver); a head impulse hands-on tutorial using a mannequin; and a video lecture on other tests useful in vertigo evaluation (nystagmus, test of skew, vestibulocular reflex, ataxia). results: thirty emergency medicine residents were studied. before and after the intervention the residents were given a survey in which one question asked ''in a patient with acute vestibular syndrome and a history and exam compatible with vestibular neuritis, i would be willing to discharge the patient without neuroimaging based on an abnormal head impulse test result that i elicited''. resident answers were based on a sevenpoint likert scale from strongly agree to strongly disagree. twenty-five residents completed both surveys. of the seven residents who changed their responses pre to post,a significant proportion ( %) changed their answer from disagree/neutral to agree after a hour vertigo day (mcnemar's test, p value = . ). conclusion: in this single-center study, teaching headimpulse testing as part of a vertigo day increases resident comfort with discharging a patient with vestibular neuritis without a ct scan. background: previous studies have been inconsistent in determining the effect of increased ed census on resident workload and productivity. we examined resident workload and productivity after the closure of a large urban ed near our facility, which resulted in a rapid % increase in our census. objectives: we hypothesized that the closure of a nearby hospital closure with a resulting influx of ed patients to our facility would not change resident productivity. methods: this computer-assisted retrospective study compared new patient workups per hour and patient load before and after the closure of a large nearby hospital. specifically, new patient workups per hour and the pm patient census per resident were examined for a one-year period in the calendar year prior to the closing and also for one year after the closing. we did not include the four month period surrounding the closure in order to determine the long-term overall effect. background: emergency medicine residents use simulation for training due to multiple factors including the acuity of certain situations they are faced with, and the rarity of others. current training on highfidelity mannequin simulators is often critiqued by residents over the physical exam findings present, specifically the auscultatory findings. this detracts from the realism of the training, and may also lead a resident down a different diagnostic or therapeutic pathway. wireless remote programmed stethoscopes represent a new tool for simulation education which allows any sound to be wirelessly transmitted to a stethoscope receiver. objectives: our goal was to determine if a wireless remote programmed stethoscope was a useful adjunct in simulation-based cases using a high-fidelity mannequin. our hypothesis was that this would represent a useful adjunct in simulation education of emergency medicine residents. methods: starting june , pgy - emergency medicine residents were assessed in two simulation-based cases using pre-determined scoring anchors. an experimental randomized crossover design was used in which each resident performed a simulation case with and without a remote programmed stethoscope on a highfidelity mannequin. scoring anchors and surveys were used to collect data with differences of means calculated. results: fourteen residents participated in the study. residents noted most realistic physical exam findings associated with the case with the adjunct in / ( %) and that their preference was for the use of the adjunct in / ( %). based off of a five-point likert scale, with being the most realistic, the adjunct-associated case averaged . as compared to . without (difference of means . , p = . ). average scores of residents with the adjunct were . / with the use of the adjunct and . / without (difference of means . , p = . ). average total times were : with the adjunct as compared to : without. conclusion: a wireless remote programmed stethoscope is a useful adjunct in simulation training of emergency medicine residents. residents noted physical exam findings to be more realistic, preferred its use, and had approached significant improvement of scores when using the adjunct. background: prior studies predict an ongoing shortage of emergency physicians to staff the nation's eds, especially in rural areas. to address this, em organizations have discussed broadening access to acgme or aoa accredited em residency programs to physicians who previously trained in another specialty and focusing on physicians already practicing in rural areas. objectives: to investigate whether em program directors (pds) from allopathic and osteopathic residency programs would be willing to accept applicants previously trained in other specialties and whether this willingness is modified by applicants' current practice in rural areas. methods: a five-question web-based survey was sent to u.s. em pds asking questions about their policies on accepting residents with past training and from rural practices. questions included whether a pd would accept a resident with prior training in other specialties, how many years from this training would the applicant be still a competitive candidate and if a physician was practicing in a rural region would the likelihood of acceptance to the program be improved. different characteristics of the residency programs were recorded including length of program, years in existence, size, type, and location of program. we compared responses by program characteristics using chi-square test. results: of the ( %) pds responding to date, a large majority ( %) reported they do accept applicants with previous residency training, although directors of osteopathic programs were less likely to accept these applicants ( % vs % for allopathic; p < . ). overall, % of pds reported no limit on the length of time from prior training to when they are accepted at an em program. % reported it is very or possibly realistic they would accept a candidate who had completed training and was board certified in another specialty. a majority of all respondents ( %) felt a physician practicing in a rural setting might be viewed as a more favorable candidate, even if the resident would only be in the program for years after receiving training credit. directors of newer programs (< years of existence) were more likely to view these candidates favorably than older programs ( % vs %; p = . ). conclusion: there appear to be many em residency programs that would at least review the application and consider accepting a candidate who trained in another specialty. a qualitative assessment of emergency medicine self-reported strengths todd guth university of colorado, aurora, co background: self-reflection has been touted as a useful way to assess the acgme core competencies. objectives: the purpose of this study is to gain insight into resident physician professional development through analysis of self-perceived strengths. a secondary purpose is to discover potential topics for selfreflective narrative essays relating to the acgme core competencies. methods: design: a small qualitative study was performed to explore the self-reported strengths of emergency medicine (em) residents in a single four-year residency. participants: all residents regardless of year of training were also asked to report their selfperceived strengths. observations: residents were asked: ''what do you feel are your greatest strengths as a resident? provide a quick description.'' the author and another reviewer identified themes from within each year of residency with abraham maslow's conscious competence conceptual framework in mind. occurrences of each theme were counted by the reviewers and organized according to frequency. once the top ten themes for each year of residency were identified and exemplar quotes identified, the two reviewers identified trends. inter-rater agreements were calculated. results: representing unconscious incompetency, the first trend was the reported presence of ''enthusiasm and a positive attitude'' from residents early in their training that decreases further along in training. additionally, a ''willingness and motivation to improve and learn'' was reported as a strength throughout all the years of training but most frequently reported in the first two years of residency. entering into conscious incompetence, the second trend identified was ''recognition of limitations and openness to constructive feedback'' that was mentioned frequently in the second and third years of residency. demonstrating conscious competence, the third trend identified was the increase in identification of the strengths of ''educational leadership, teamwork skills and communication, and departmental patient flow and efficiency'' in the later years of residency. conclusion: self-reported strengths has helped to identify both themes within each year of residency and trends among the years of residency that can serve as areas to explore in self-reflective narratives relating to the acgme core competencies. training. pofu can also be used to assess the acgme core competency of practice-based learning. the exact form or frequency of pofu assessment among various em residencies, however, is not currently known. objectives: we aimed to survey em residencies across the country to determine how they fulfill the pofu requirement and whether certain program structure variables were associated with different pofu systems. we hypothesized that implementation of pofu systems among em residencies would be highly variable. methods: in this irb-approved study, all program directors of acgme allopathic em residencies were invited to complete a -question survey on their current approaches to pofu. respondents were asked to describe their current pofu system's characteristics and rate its ease of use, effectiveness, and efficiency. data were collected using surveymonkey(tm) and reported using descriptive statistics. results: of residencies surveyed, ( %) submitted complete data. . % were completed by program directors and over three-fourths ( . %) of em residencies require monthly completion of pofus. the mean total pofus required per year was ( % ci - ), with a median of and a range of - . almost / ( %) of residencies use an electronic pofu system. most ( %) -year em residencies use an electronic pofu system, compared with half ( %) of -year residencies (difference %, p = . , % ci . %- . %). seven commercially available electronic programs are used by % of the residencies, while % use a customized product. most respondents ( %) rated their pofu system as easy to use, but less than half ( %) felt it was an effective learning tool or an efficient one ( %). onethird ( %) would use a different pofu system if available, and almost half ( %) would be interested in using a multi-residency pofu system. conclusion: em residency programs use many different strategies to fulfill the rrc requirement for pofu. the number of required pofus and the method of documentation vary considerably. about two-thirds of respondents use an electronic pofu system. less than half feel that pofu logs are an effective or efficient learning tool. background: certification of procedural competency is requisite to graduate medical education. however, little is known regarding which platforms are best suited for competency assessment. simulators offer several advantages as an assessment modality, but evidence is lacking regarding their use in this domain. furthermore, perception of an assessment environment has important influence on the quality of learning outcomes, and procedural skill assessment is ideally conducted on a platform accepted by the learner. objectives: to ascertain if a simulator performs as well as an unembalmed cadaver with regard to residents' perception of their ability to demonstrate procedural competency during ultrasound (us) guided internal jugular vein (ij) catheterization. methods: in this cross-sectional study at an urban community hospital during july of , residents in their second or third year of training from a -year em residency program performed us guided catheterizations of the ij on both an unembalmed cadaver and a simulator manufactured by blue phantom. after the procedure, residents completed an anonymous survey ascertaining how adequately each platform permitted their demonstration of proficiency on predefined procedural steps. answers were provided on a likert scale of to , with being poor and being excellent. p values < . were considered educationally significant. results: the median overall rating of the simulator (s) to serve as an assessment platform was similar to that of the cadaver (c) with scores of . and . respectively, p = . . median ratings for permitting the demonstration of specific procedural steps were as follows: conclusion: senior em residents positively rate the blue phantom simulator as an assessment platform and similarly to that of a cadaver with regard to permitting their demonstration of procedural competency for us guided ij catheterization, but did prefer the cadaver to a greater degree when identifying and guiding the needle into the ij. methods: in fall , wcmc and wcmc-q students taking the course completed a question pre-and post-test. wcmc-q students also completed a postcourse single-station objective structured clinical examination (osce) that evaluated their ability to identify and perform eight actions critical for a first responder in an emergency situation (table ) . results: on both campuses, mean post-test scores were significantly higher than mean pre-test scores (p £ . ). on the pre-test, mean wcmc student scores were significantly higher than for wcmc-q students (p = . ); however, no difference was found in mean post-test scores (p = . ). there was no association between the scores on the osce (mean = . , sd = . ) and the post-test (p = . ) even after adjusting for a possible evaluators' effect (table ) . clinical skills course was effective in enhancing student knowledge in both qatar and new york as evidenced by the significant improvement in scores from the pre-to post-tests. the course was able to bring wcmc-q student scores and presumably knowledge up to the same level as wcmc students. students performed well on the osce, suggesting that the course was able to teach them the critical actions required of a first responder. the lack of association between the post-test and osce scores suggests that student knowledge does not independently predict ability to learn and demonstrate critical actions required of a first responder. future studies will evaluate whether the course affects the students' clinical practice. assess breathing assess circulation call ems call ems and assess abcs prior to other interventions immobilize localize and control bleeding splint fractured extremity and skills specific to wilderness medicine by incorporating simulated medical scenarios into a day-long adventure race. this event has gained acceptance nationally in wilderness medical circles as an excellent way to appreciate the challenges of wilderness medicine, however its effectiveness as a teaching tool has not yet been verified. objectives: the objective of this study was to determine if improvement in simulated clinical and didactic performance can be demonstrated by teams participating in a typical medwar event. methods: we developed a complex clinical scenario and written exam to test the basic tenets that are reinforced through the medwar curriculum. teams were administered the test and scored on a standardized scenario immediately before and after the midwest medwar race. teams were not given feedback on their pre-race performance. scenario performance was based on the number of critical actions correctly performed in the appropriate time frame. data from the scenario and written exams were analyzed using a standard paired difference t-test. results: a total of teams participated in both the pre-and post-event scenarios. the teams' pre-race scenario performance was . % (sd = . , n = ) of critical actions met compared to a post-race performance of . % (sd = . , n = ). the mean improvement was . % (sd = . , n = , % ci . , . ) with a significant paired two-tailed t-test (p £ . ). a total of individual subjects took the written pre-and posttests. the written scores averaged pre-race . % (sd = . , n = ) and post-race . % (sd = . , n = ). the mean improvement was . % (sd = . , n = , ci ) . , . ), with a significant paired twotailed t-test (p £ . ). conclusion: medwar participants demonstrated a significant improvement in both written exam scores and the management of a simulated complex wilderness medical scenario. this strongly suggests that medwar is an effective teaching platform for both wilderness medicine knowledge and skills. palliative methods: ed residents and faculty of an urban, tertiary care, level i trauma center were asked to complete an anonymous survey ( / - / ). participants ranked statements on a five-point likert scale ( = strongly disagree- = strongly agree). statements covered four main domains of barriers related to: ) education/training, ) communication, ) ed environment; ) personal beliefs. respondents were also asked if they would call pc consult for ed clinical scenarios (based on established triggers). results: / ( %) eligible participants completed the survey ( residents, faculty), average age was years, % ( / ) male, and % ( / ) caucasian. respondents identified two major barriers to ed-pc provision: lack of hour availability of pc team (mean score . ) and lack of access to complete medical records ( . ). listed domain barriers included: communication-related issues (mean . ) like access to family or primary providers, ed environment ( . ) for example chaotic setting with time-constraints, education/training ( . ) related to pain/pc, and personal beliefs regarding end-of-life ( . ). all respondents agreed that they would call pc consult for a 'hospice patient in respiratory distress', and a majority ( %) would consult pc for 'massive intracranial hemorrhage, traumatic arrest, and metastatic cancer'. however, traditional in-patient triggers like frequent re-admits for organ failure issues (dementia, congestive heart failure, and obstructive pulmonary disease exacerbations) were infrequently ( %) chosen for pc consult. conclusion: to enhance pc provision in the ed setting, two main ed physician perceived barriers will likely need to be addressed: lack of access to medical records and lack of - availability of pc team. ed physicians may not use the same criteria to initiate pc consults as compared to the traditionally established inpatient pc consult trigger models. percent of charts with an mse by ait prior to resident evaluation (a measure of reduced diagnostic uncertainty and decision-making), ( ) ed volume. results: there were no educationally significant differences in productivity or acuity between the pre-ait and post-ait groups. mse was recorded in the chart prior to resident evaluation in . % of cases. ed volume rose by . % between periods. conclusion: ait did not affect productivity or acuity of patients seen by em s. while some volume was directed away from residents by ait (patients treated-andreleased by ait only), overall volume increased and made up the difference. this is similar to previously reported rankings that program directors gave to the same criteria. although medical students agreed with program directors on the importance of most aspects of the nrmp application areas of discordance included higher medical student ranking for extracurricular activities and a lower relative ranking for aoa status than program directors. this can have implications for medical student mentoring and advising in the future. background: emergency care of older adults requires specialized knowledge of their unique physiology, atypical presentations, and care transitions. older adults often require distinctive assessment, treatment and disposition. emergency medicine (em) residents should develop expertise and efficiency in geriatric care. older adults represent over % of most emergency department (ed) volumes. yet many em residencies lack curricula or assessment tools for competent geriatric care. the geriatric emergency medicine competencies (gemc) are high-impact geriatric topics developed to help residencies meet this demand. objectives: to examine the effect of a brief gemc educational intervention on em resident knowledge. methods: a validated -question didactic test was administered at six em residencies before and after a gemc focused lecture delivered summer and fall of . scores were analyzed as individual questions and in defined topic domains using a paired student's t-test. results: a total of exams were included. the testing of didactic knowledge before and after the gemc educational intervention had high internal reliability ( . %). the intervention significantly improved scores in all domains (table ) . graded increase in geriatric knowledge occurred by pgy year with the greatest improvement seen at the pgy level (table ) . conclusion: even a brief gemc intervention had a significant effect on em resident knowledge of critical geriatric topics. a formal gemc curriculum should be considered in training em residents for the demands of an ageing population. the overall procedure experience of this incoming class was limited. most r s had never received formal education in time management, conflict of interest management, or safe patient trade-off. the majority lacked confidence in their acute and chronic pain management skills. these entry level residents lacked foundational skill levels in many knowledge areas and procedures important to the practice of em. ideally medical school curricular offerings should address these gaps; in the interim, residency curricula should incorporate some or all of these components essential to physician practice and patient safety. background: the american heart association and international liaison committee on resuscitation recommend patients with return of spontaneous circulation following cardiac arrest undergo post-resuscitation therapeutic hypothermia. in post-cardiac arrest patients presenting with a rhythm of vf/vt, therapeutic hypothermia has been shown to reduce neurologic sequelae and decrease overall mortality. objectives: to explore clinical practice regarding the use of therapeutic hypothermia and compare survival outcomes in post-cardiac arrest patients. a secondary outcome was to assess whether the initial presenting cardiac arrest rhythm (ventricular fibrillation/ventricular tachycardia (vf/vt) versus pulseless electrical activity (pea) or asystole) was associated with differences in outcomes. methods: a retrospective medical record review was conducted for all adult ( ‡ years) post-cardiac arrest patients admitted to the icu of an academic tertiary care centre (annual ed census , ) from - . data were extracted using a standardized data collection tool by trained research personnel. results: patients were enrolled. mean (sd) age was ( ) and . % were male. of ( . %) patients treated with hypothermia, ( . %) presented with an initial rhythm of vf/vt and ( . %) presented with pea or asystole. nine ( . %) patients with vf/vt were treated with therapeutic hypothermia and discharged from hospital compared to ( . %) patients with pea or asystole (d . %; % ci: . %, . %). of patients not treated with hypothermia, ( . %) presented with vf/vt, ( . %) presented with pea or asystole, and ( . %) initial rhythms were unknown. fifteen ( . %) patients with vf/vt, not treated with hypothermia, were discharged from hospital compared to ( . %) patients with pea or asystole (d . %; % ci: . %, . %). regardless of initial presenting rhythm or initiation of therapeutic hypothermia, ( . %) discharged patients had good neurological function as assessed by the cerebral performance category (cpc score - ). conclusion: although recommended, post-cardiac arrest therapeutic hypothermia was not routinely used. patients with vf/vt and treated with hypothermia had better outcomes than those with pea or asystole. further research is needed to assess whether cooling patients with presenting rhtyhms of pea or asystole is warranted. racial background: chronic obstructive pulmonary disease (copd) is a major public health problem in many countries.the course of the disease is characterised by episodes, known as acute exacerbations (ae), when symptoms of cough, sputum production, and breathlessness become much worse. the standard prehospital management of patients suffering from an aecopd includes oxygen therapy, nebulised bronchodilators, and corticosteroids. high flow oxygen is used routinely in prehospital areas for breathless patients with copd. there is little high quality evidence on the benefits or potential dangers in this setting but audits have shown increased mortality, acidosis, and hypercarbia in patients with aecopd treated with high flow oxygen. objectives: to compare standard high flow oxygen treatment with titrated oxygen treatment for patients with an aecopd in the prehospital setting. methods: cluster randomized controlled parallel group trial comparing high flow oxygen treatment with titrated oxygen treatment in the prehospital setting. in an intention to treat analysis (n = ), the risk of death was significantly lower in the titrated oxygen arm compared with the high flow oxygen arm for all patients and for the subgroup of patients with confirmed copd (n = ). overall mortality was % ( deaths) in the high flow oxygen arm compared with % ( deaths) in the titrated oxygen arm; mortality in the subgroup with confirmed copd was % ( deaths) in the high flow arm compared with % ( deaths) in the titrated oxygen arm. titrated oxygen treatment reduced mortality compared with high flow oxygen by % for all patients (p = . ) and by % for the patients with confirmed chronic obstructive pulmonary disease (p = . ). patients with copd who received titrated oxygen according to the protocol were significantly less likely to have respiratory acidosis or hypercapnia than were patients who received high flow oxygen. conclusion: titrated oxygen treatment significantly reduced mortality, hypercapnia, and respiratory acidosis compared with high flow oxygen in aecopd. these results provide strong evidence to recommend the routine use of titrated oxygen treatment in patients with breathlessness and a history or clinical likelihood of copd in the prehospital setting. (originally submitted as a ''late-breaker.'') trial registration australian new zealand clinical trials register actrn . background: toxic particulates and gases found in ambulance exhaust are associated with acute and chronic health risks. the presence of such materials in areas proximate to ed ambulance parking bays, where emergency services' vehicles are often left running, is potentially of significant concern to ed patients and staff. objectives: investigators aimed to determine whether the presence of ambulances correlated with ambient particulate matter concentrations and toxic gas levels at the study site ed. methods: the ambulance exhaust toxicity in healthcare-related exposure and risk [aether] program conducted a prospective observational study at an academic urban ed / level i trauma center. environmental ambient gas was sampled over a continuous five-week period from september to october . two sampling locations in the public triage area (public patient dropoff area without ambulances) and three sampling locations in the ambulance triage area were randomized for -hour monitoring windows with a temporal resolution of minutes to obtain days of non-contiguous data for each location. concentrations of particulate matter less than . microns in aerodynamic size (pm . ), oxygen, hydrogen sulfide (h s), and carbon monoxide (co) as well as lower explosive limit for methane (lel) were monitored with professionally calibrated devices. ambulance traffic was recorded through offline review of / security video footage of the site's ambulance bays. results: , measurements at the public triage nurse desk space revealed pm . concentrations with a mean of . ± . lg/m (median . lg/m ; maximum , . lg/m ). , ambulance triage nurse desk space pm . concentrations recorded a mean of . ± . lg/m (p < . , unpaired t test; median . lg/m ; maximum . lg/m ). oxygen levels remained steady throughout the study period; co, h s, and lel were not detected. ambulance activity levels had the highest correlations with pm . concentrations at the ambulance triage foyer (r = . ) and desk area (r = . ) where patients wait and ed staff work - hr shifts. conclusion: ed spaces proximate to ambulance parking bays had higher levels of pm . than areas without ambulance traffic. concentrations of ambient particulate matter in acute care environments may pose a significant health threat to patients and staff. an ems ''pit crew'' model improves ekg and stemi recognition times in simulated prehospital chest pain patients sara y. baker , salvatore silvestri , christopher d. vu , george a. ralls , christopher l. hunter , zack weagraff , linda papa orlando regional medical center, orlando, fl; florida state university college of medicine, orlando, fl background: prehospital teams must minimize time to ekg acquisition and stemi recognition to reduce overall time from first medical contact to reperfusion. auto-racing ''pit crews'' model rapid task completion by pre-assigning roles to team members. objectives: we compared time-to-completion of key tasks during chest pain evaluation in ems teams with and without pre-assigned roles. we hypothesized that ems teams using the ''pit crew'' model would improve time to recognition and treatment of stemi patients. methods: a randomized, controlled trial of paramedic students was conducted over months at orlando medical institute, a state-approved paramedic training center. we compared a standard ems chest pain management algorithm (control) with a pre-assigned tasks (''pit crew'') algorithm (intervention) in the evaluation of simulated chest pain patients. students were randomized into groups of three; intervention and control groups did not interact after randomization. all students reviewed basic prehospital chest pain management and either the standard or pre-assigned tasks algorithm. groups encountered three simulated patients. laerdal simmanÒ software was used track completion of tasks: taking vital signs, iv access, ekg acquisition and interpretation, asa administration, hospital stemi notification, and total time on scene. results: we conducted simulated-patient encounters ( control / intervention encounters). mean time-to-completion of each task was compared in the control and intervention groups respectively. time to obtain vital signs was : vs. : min (p = . ); time to asa administration was : vs : min (p < . ); time to ekg acquisition was : vs : min (p < . ); time to ekg interpretation was : vs : min (p < . ); time to iv access was : vs : min (p = . ); time to stemi notification was : vs : min (p < . ); and time to scene completion was : vs : min (p < . ). conclusion: paramedic student teams with pre-assigned roles (the ''pit crew'' model) were faster to obtain vital signs, administer asa, acquire and interpret the ekg, stemi notification, and overall time on scene during simulated patient encounters. further study with experienced ems teams in actual patient encounters is necessary to confirm the relevance of these findings. background: use of automated external defibrillators (aed) has remained low in the u.s. understanding the effect of neighborhoods on the probability of having an aed used in the setting of a public arrest may provide important insights for future placement of aeds. objectives: to determine associations between the racial and income composition of neighborhoods (as defined by u.s. census tracts), individual arrest characteristics, and whether bystanders or first responders initiate aed use. methods: cohort study using surveillance data prospectively submitted by emergency medical services systems and hospitals from u.s. sites to the cardiac arrest registry to enhance survival between october , and december , . neighborhoods were defined as high-income vs. low-income based on the median household income being above or below $ , and as white or black if > % of the census tract was of one race. neighborhoods without a predominant racial composition were defined as integrated. arrests that occurred within a public location (excluding medical facilities and airports) were eligible for inclusion. hierarchical multi-level modeling, using stata v . , was used to determine the association between individual and census tract characteristics on whether an aed was used. results: of , eligible cases, an aed was used in arrests ( . %) by a first responder (n = , , . %) or bystander (n = , . %). patients whose arrest was witnessed (odds ratio [or] . ; % confidence interval [ci] . - . ) were more likely to have an aed used (table) . when compared to high-income white neighborhoods, arrest victims in low-income black neighborhoods were least likely to have an aed used (or . ; % ci . - . ). arrest victims in lowincome white (or . ; % ci . - . ) and lowincome integrated (or . ; % ci . - . ) were also less likely to have an aed used. conclusion: arrest victims in black and low-income neighborhoods are least likely to have an aed used by a layperson or first responder. future research is needed to better understand the reasons for low rates of aed use for cardiac arrests in these neighborhoods. the impact of an educational intervention on the pre-shock pause interval among patients experiencing an out-of-hospital cardiac arrest jonathan studnek , eric hawkins , steven vandeventer carolinas medical center, charlotte, nc; mecklenburg ems agency, charlotte, nc background: pre-shock pause duration has been associated with survival to hospital discharge (std) among patients experiencing out-of-hospital cardiac arrest (oohca) resuscitation. recent research has demonstrated that for every -second increase in this interval there is an % decrease in std. objectives: determine if a decrease in the pre-shock pause interval for patients experiencing oohca could be realized after implementation of an educational intervention. methods: this was a retrospective analysis of data obtained from a single als urban ems system from / / to / / and / / to / / . in august , an educational intervention was designed and delivered to approximately paramedics emphasizing the importance of reducing the time off chest during cpr. specifically, the time period just prior to defibrillation was emphasized by having rescuers count every th compression and pre-charge the defibrillator on the th compression. in order to determine if this change resulted in process improvement, months of data were assessed before and months after the educational intervention. pre-shock pause was the outcome variable and was defined as the time period after compressions ceased until a shock was delivered. this interval was measured by a cpr feedback device connected to the defibrillator. inclusion criteria were adult patients who required at least one defibrillation and had the cpr feedback device connected during the defibrillation attempt. analysis was descriptive utilizing means and % ci as well as wilcoxon rank sum test to assess difference between the two time periods. results: in the pre-intervention period there were patients who received defibrillations compared to patients receiving defibrillations in the post-intervention phase. the mean duration of the pre-shock pause pre-intervention was seconds ( % ci - ) while the post-intervention duration was seconds ( % ci - ). the difference in pre-shock pause duration was statistically significant with p < . . conclusion: these data indicate that after a simple educational intervention emphasizing decreasing time off chest prior to defibrillation the pre-shock pause duration decreased. future research must describe the sustainability of this intervention as well as the effects this process measure may have on outcomes such as survival to hospital discharge. background: the broselow tape (bt) has been used as a tool for estimating medication dosing in the emergency setting. the obesity trend has demonstrated a tendency towards insufficient pediatric weight estimations from the bt, and thus potential under-dosing of resuscitation medications. objectives: this study compared drug dosing based on the bt with dosing from a novel electronic tool (et) that accounts for provider estimation of body habitus. methods: data were obtained from a prospective convenience sample of children ages to years arriving to a pediatric emergency department. a clinician performed an assessment of body habitus (average/underweight, overweight, or obese), blinded to the patient's actual weight and parental weight estimate. parental estimate of weight and measured length and weight were collected. epinephrine dosing was calculated from the measured weight, the bt measurement, as well as from a smart-phone tool based on the measured length and clinician's estimate of body habitus, and a modified tool (mt) incorporating the parent estimate of habitus. the wilcoxson rank-sum test was used to compare median percent differences in dosing. results: one hundred children (mean age years) were analyzed; % were overweight or obese. clinicians correctly identified children as overweight/obese % of time (ci . - . ). adding parent estimate of weight improved this to a sensitivity of % (ci . - . ). the median difference between the weight-based epinephrine dose and bt dose was %. for the et the median difference from the weight-based dose was % (p = . compared to the bt), and for the mt was . % (p < . compared to the bt). when a clinically significant difference was defined as ± % of the actual dose, bt was within that range % of the time, et was within range % of the time (p = . ), and mt was within range % of the time ( background: in most out-of-hospital cardiac arrest (ohca) events, a call to - - is the first action by bystanders. accurate diagnosis of cardiac arrest by the call taker depends on the caller's verbal description. if cardiac arrest is not suspected, then no telephone cpr instructions will be given. objectives: we measured the effect of a change in the ems call taker question sequence on the accuracy of diagnosis of cardiac arrest by - - call takers. methods: we retrospectively reviewed the cardiac arrest registry to enhance survival (cares) dataset for january , through june , from a city, population , , with a longstanding telephone cpr program (apco). we included ohca cases of any age who were in arrest prior to the arrival of ems and for whom resuscitation was attempted. in early , - - call takers were taught to follow a revised telephone script that emphasized focused questions, assertive control of the caller, and provision of hands-only cpr instructions. the medical director personally explained the reasons for the changes, emphasizing the importance of assertive control of the caller and the comparative safety of chest compressions in patients not in cardiac arrest. beginning in , call recordings were reviewed regularly with feedback to the call taker by the - - center leadership. the main outcome measure was sensitivity of the - - call taker in diagnosing cardiac arrest. bystander cpr was reported by ems crews attending the event. we compared with and using the v test and odds ratios (or). results: there were ohca cases in , cases in , and in the first half of ( / , population). the mean age was ± years, and % of the events were witnessed. before the revision, % of ohca cases were identified by - - dispatchers; and after the revised questioning sequence, % were identified (or . , % ci . - . ). the false positive rate changed little (from /month to /month). the mean time to question callers was unchanged ( vs seconds). bystander cpr was performed in . % of events in , . % in , and . % of events in (p < . ). conclusion: emphasis on scripted assessment improved sensitivity without loss of specificity in identifying ohca. with repeated feedback, it translated to an increase in victims receiving bystander cpr. in an out-of hospital cardiac arrest population confirmed by autopsy salvatore silvestri, christopher hunter, george ralls, linda papa orlando regional medical center, orlando, fl background: quantitative end-tidal carbon dioxide (etco ) measurements (capnography) have consistently been shown to be more sensitive than qualitative (colorimetric) ones, and the reliability of capnography for assessing airway placement in low perfusion states has sometimes been questioned in the literature. objectives: this study examined the rate of capnographic waveform presence of an intubated out-of-hospital cardiac arrest cohort and its correlation to endotracheal tube location confirmed by autopsy. our hypothesis is that capnography is % accurate in determining endotracheal tube location, even in low perfusion states. methods: this cross-sectional study reviewed a detailed prehospital cardiac arrest database that regularly records information using the utstein style. in addition, the ems department quality manager routinely logs the presence of an alveolar (four-phase) capnographic waveform in this database. the study population included all cardiac arrest patients from january , through december , managed by a single ems agency in orange county, florida. patients were included if they had endotracheal intubation performed, had capnographic measurement obtained, failed to regain return of spontaneous circulation (rosc), and had an autopsy performed. the main outcome was the correlation of the presence of an alveolar waveform and the location of the ett at autopsy. results: during the study period, cardiac arrests were recorded. of these, had an advanced airway placed (ett or laryngeal tube airway), and no rosc. of the advanced airway cases, were managed with an ett. autopsies were performed on of these patients and resulted in our study cohort. the location of the ett at autopsy was recorded on all of these cases. capnographic waveforms were recorded in the field in all of these study patients, and % of the tubes were located within the trachea at autopsy. the sensitivity of capnography in determining proper endotracheal tube location was % in this study. conclusion: in our study, the presence of a capnographic waveform was % reliable in confirming proper placement of endotracheal tubes placed in outof-hospital patients with poor perfusion states. results: over variables were presented to the ems medical directors responding ( % survey population captured). among the myriad of responses, ( %) initiate cardiopulmonary resuscitation (cpr) at compressions to ventilations consistent with il-cor/aha guidelines. seven ( %) initiate continuous chest compressions from the start of cpr with no pause and interposed ventilations. nine ( %) begin chest compressions only during the first - minutes, with either passive oxygenation by oxygen mask (six; %) or no oxygen (three; %). airway management following non-invasive oxygenation and ventilation by primary endotracheal intubation occurs in systems ( %), while six ( %) use supraglottic devices. fourteen ( %) allow paramedics to decide between endotracheal and supraglottic device placement. thirty systems ( %) utilize continuous waveform capnography. the initial approach to non-ems witnessed ventricular fibrillation is chest compression prior to first defibrillation in systems ( %). eighteen systems ( %) escalate defibrillation energy settings, with four systems ( %) utilizing dual sequential defibrillation. twenty ( %) initiate therapeutic hypothermia in the field. conclusion: wide variability in ca care standards exists in america's largest urban ems systems in mid- , with many current practices promoting more continuity in chest compressions than specified in the ilcor/aha guidelines. endotracheal intubation, a past mainstay of ca airway management, is deemphasized in many systems. immediate defibrillation of non-ems witnessed ventricular fibrillation is uncommon. objectives: determine the out-of-hospital cardiac arrest survival in this area of puerto rico using the utstein method. methods: prospective observational cohort study of adult patients presenting with an out-of-hospital cardiac arrest to the upr hospital ed. study endpoints will be survival and neurologically intact survival at hospital discharge, months, and months. results: a total of consecutive cardiac arrest events were analyzed for a period of years. one-hundred fifteen events met criteria for primary cardiac etiology ( . %). the average age for this group was . years. there were female ( . %) and male ( . %) participants. the average time to start cpr was . minutes. transportation to the ed was . % by ems and . % by private vehicle. a total of events were witnessed ( . %). the survival rate to hospital admission was . %. the overall cardiac arrest survival was . % and overall neurologically intact survival was . %. neurologically intact survival at and months was . %. the rate of bystander cpr in our population was . % with a survival rate of . %. conclusion: survival from out-of-hospital cardiac arrest in the area served by the upr hospital is low but comparable to other cities in the us as reported by the cdc cardiac arrest registry to enhance survival (cares). this low survival rate might be due to low bystander cpr rate and prolonged time to start cpr. background: hyperventilation has been directly correlated with increased mortality for out-of-hospital cpr. ems providers may hyperventilate patients at levels above national bls guidelines. real-time feedback devices, such as ventilation timers, have been shown to improve cpr ventilation rates towards bls standards. it remains unclear if the combination of a ventilation timer and pre-simulation instruction would influence overall ventilation rates and potentially reduce undesired hyperventilation. objectives: this study measured ventilation rates of standard cpr (and pre-instruction on effects of hyperventilation) compared to cpr with the use of a commercial ventilation timer (and pre-instruction on effects of hyperventilation). we propose that use of a ventilation timer, measuring and displaying to ems providers real-time ventilations delivered, will have no difference in ventilation rates when comparing these groups. methods: this prospective study placed ems providers into four groups: two controls measuring ventilation rates before ( a) and after instruction ( b) on the deleterious effects of hyperventilation, and a concurrent intervention pair with before ( a) and after instruction ( b), with the second pair measuring ventilation rates with a ventilation timer that provides immediate feedback on respirations given. ventilation rates were measured for a -second period after one minute of simulated cpr using mannequins. the control set without instruction ( a, n = ) averaged . breaths ( % ci = . - . ) and with instruction ( b, n = ) averaged . breaths ( % ci = . - . ). the intervention set without instruction ( a, n = ) averaged . breaths ( % ci = . - . ) and with instruction ( b, n = ) averaged . breaths ( % ci = . - . ). there was a significant improvement (p = . ) in ventilation rates with use of a ventilation timer (control group versus intervention group regardless of pre-instruction). there was no statistically significant difference between groups with respect to instruction alone (p = . ). conclusion: the use of a ventilation timer significantly reduced overall ventilation rates, providing care closer to bls guidelines. the addition of pre-simulation instruction added no significant benefit to reducing hyperventilation. background: in , the american heart association (aha) recommended a compression rate of (roc) / min and a depth of compressions (doc) at least inches for effective cpr. as an educational tool for lay rescuers, the aha as adopted the catch phrase ''push hard, push fast''. objectives: in this irb-exempt study, we sought to determine if persons without formal cpr training could perform non-ventilated cpr as well as those who have been trained in the past or those currently certified. methods: a convenience sample of patrons of the new york state fair was asked to perform minutes of hands-only cpr on a prestan pp-am- m adult cpr manikin. these devices provide visual indicators of acceptable rate and depth of compressions. each subject was video recorded on a dell latitude laptop computer with a logitech quick cam using logitech quick cam . . for windows software. results: a total of volunteers ( male, female) aged - years participated: were never certified (nc) in cpr, were previously certified (pc), and were currently certified (cc). there was no difference in age across the groups. the cc group had a higher proportion of females (chi-square = . , p < . ). cc volunteers sustained roc and doc for an average of . seconds as compared to an average of . seconds (pc) and . seconds (nc) respectively. (f = . , p < . ). the cc maintained roc of closer to / min (mean . /min) when compared to the pc (mean . /min) and nc (mean . /min) groups (f = . , p < . ). a higher proportion of volunteers of the cc group were able to perform adequate doc (chi-square = . , p < . ), and hand placement (chisquare = . , p < . ) when compared to the other two groups. conclusion: compared to the target roc and doc, none of the groups did well and only subjects met target roc/doc. increased out-of-hospital cardiac arrest survivability due to lay rescuer intervention is only assured if cpr is effectively administered. the effect and benefit of maintaining formal cpr training and certification is clear. background: more than , out-of-hospital cardiac arrests (ohcas) occur annually in the united states (us). automated external defibrillators (aeds) are life-saving devices in public locations that can significantly improve survival. an estimated million aeds have been sold in the us; however, little is known about whether locations of aeds match oh-cas. these data could help determine optimal placement of future aeds and targeted cpr/aed training to improve survival. objectives: we hypothesized that the majority (> %) of aeds are not located in close proximity ( feet) to the occurrence of cardiac arrests in a major metropolitan city. methods: this was a retrospective review of prospectively collected cardiac arrest data from philadelphia ems from january , until december , . included were ohcas of presumed cardiac etiology in individuals years of age or older. excluded were oh-cas of presumed traumatic etiology, cases where resuscitation was terminated at the scene, and those dead on arrival. aed locations in philadelphia were obtained from myheartmap, a database of installed and wallmounted aeds in pennsylvania. we used gis mapping software to visualize where ohcas occurred relative to where aeds were located and to determine the radius of ohcas to aeds. arrests within a , , and foot radius of aeds were identified using the attribute location selection option in arcgis. the lengths of radii were estimated based on the average time it would take for a person to walk to and from an aed ( feet minutes; feet minutes; feet minutes). results: we mapped , ohcas and , aeds in philadelphia county. ohcas occurred in males ( %; / ) and the mean age was . years. ventricular fibrillation occurred in % ( / ). aeds were primarily located in schools/universities ( %), office buildings ( %), and residential buildings ( %). aeds were not identified within feet in % ( , ) of ohcas, within feet of % ( , ) of ohcas, and within feet in % ( , ) of ohcas. the figure (large black circles) illustrates aed/ohca within feet on the left and feet on the right. conclusion: aeds were rarely close to the locations of ohcas, which may be a contributor to low cardiac arrest survival rates. innovative models to match aed availability with ohcas should be explored. (originally submitted as a ''late-breaker.'') potential background: early and frequent epinephrine administration is advocated by acls; however, epinephrine research has been conducted primarily with standard cpr (std). active compression-decompression cpr with an impedance threshold device (acd-cpr + itd) has become the standard of care for out of hospital cardiac arrest in our area. the hemodynamic effects of iv epinephrine under this technique are not known. objectives: to determine the hemodynamic effects of iv epinephrine in a swine model undergoing acd-cpr+itd. methods: six female swine ( ± kg) were anesthetized, intubated, and mechanically ventilated. intracranial, thoracic aorta, and right atrial pressures were recorded via indwelling catheters. carotid blood flow (cbf) was recorded via doppler. etc , sp , and ekg were monitored. ventricular fibrillation was induced and went untreated for minutes. three minutes each of standard cpr (std), std-cpr+itd, and acd-cpr+itd was preformed. at minute of the resuscitation, lg/kg of iv epinephrine was administered and acd-cpr+itd was continued for minute. statistical analysis was performed with a paired t-test. results: aortic pressure and calculated cerebral and carotid perfusion pressures increased from std < std+itd < acd-cpr+itd (p £ . ). epinepherine administered during acd-cpr+itd signficantly increased mean aortic ( ± vs ± , p = . ), cerebral ( ± vs ± , p = . ), and coronary perfusion pressures ( ± vs ± , p = . ); however, mean cbf and etco decreased (respectively ± vs ± . , p = . ; ± vs ± , p = . ). conclusion: the administration of epinepherine during acd-cpr+itd signficantly increased markers of macrocirculation, while significantly decreasing etco , a proxy for organ perfusion. while the calculated cerebral perfusion pressures increased, the directly measured cbf decreased. this calls into question the ability of calculated perfusion pressures to accurately reflect blood flow and oxygen delivery to end organs. hypoxia background: during cardiac arrest most patients are placed on % oxygen with assisted ventilations. after return of spontaneous circulation (rosc), % oxygen is typically continued for an extended time. animal data suggest that immediate post-arrest titration of oxygen by pulse oximetry produces better neurocognitive/ histologic outcomes. recent human data suggest that arterial hyperoxia is associated with worse outcomes. objectives: to assess the relationship between hypoxia, normoxia, and hyperoxia post-arrest and outcomes in post-cardiac arrest patients treated with therapeutic hypothermia. methods: we conducted a retrospective chart review of post-arrest patients admitted to an academic medical center between january, and december, who had arterial blood gases (abg) drawn after rosc. demographic variables were analyzed using anova and chi-square tests as appropriate. unadjusted logistic regression analyses were performed to assess the relationship between hypoxia (pao < mmhg), normoxia ( - mmhg), hyperoxia (> mmhg), and mortality. results: on first abg ( patients), ( . %) were hypoxic, ( . %) normoxic, and ( . %) hyperoxic. the average age of the cohort was . years (no difference for hypoxic, normoxic, and hyperoxic patients). overall mortality was . % ( / ). there were no significant differences between initial heart rate, systolic blood pressure, sex, race, or pre-arrest functional status. in-hospital mortality was significantly higher when the first abg demonstrated hypoxia ( . %; / ) than for normoxia ( . %; / ) or hyperoxia ( %; / ). in unadjusted logistic regression analysis of first pao values, hyperoxia was not associated with increased mortality (or . ; % ci . - . ) but hypoxia was associated with increased mortality (or . ; % ci . - . ). conclusion: hypoxia but not hyperoxia on first abg was associated with mortality in a cohort of post-arrest patients. background: there are over , deaths due to cardiac arrest per year in the us. the aha recommends monitoring the quality of cpr primarily through the use of end tidal co (etco ). the level of etco is significantly dependant on minute ventilation and altered by pressor and bicarbonate use. cerebral oximetry (cereox) uses near infrared spectroscopy to non-invasively measure oxygen saturation of the frontal lobes of the brain. cereox has been correlated with cerebral blood flow and jugular vein bulb saturations. objectives: the objective of this study is to compare the simultaneous measurement of etco and cereox to investigate which monitoring method provides the best measure of cpr quality as defined by return of spontaneous circulation (rosc). methods: a prospective cohort of a convenient sample of patients using out-of-hospital and ed cardiac arrest from two large eds. patients were monitored simultaneously by etco and cereox during cpr. patient demographics and arrest data were collected using the utstein criteria. all patients were monitored throughout the resuscitation efforts. rosc was defined as a palpable pulse and a measurable blood pressure for a minimum of thirty minutes. results: twenty two patients were enrolled with complete data sets; % of the subjects had rosc. average down time of rosc subjects was minutes (sd ± . ) and minutes (sd ± . ) for subjects without rosc. the inability to obtain a value of either for etco or cereox was % and % specific with an % and % npv respectively for predicting lack of rosc. obtaining a value of either for etco or cereox was % and % sensitive, respectively in identifying rosc. subjects with rosc had sustained values above for . mins on cereox and . mins on etco prior to rosc. the increase in values over a three minute period prior to rosc was . on cereox and . on etco . conclusion: the inability to obtain a value of on either the etco or cereox strongly predicted lack of rosc. cereox provides a larger magnitude and closer temporal increase prior to rosc than etco . attaining a value of on cereox was more predictive of rosc than etco . an discrepancies due to communicating information to multiple listeners in a short amount of time. this creates a communication barrier not always apparent to practitioners. we examine the perceptions of ems and ed personnel on the transfer of care and its correlation to missing patient data. objectives: evaluate provider perception of information transfer by ems and ed personnel and compare this to an external observer's objective assessment. methods: this is a retrospective quality improvement program at an academic level i trauma center. transfers of medical and trauma patients from ems to ed personnel were attended by trained external observers, research associates (ra). ra recorded the data communicated: name, age, past medical history (pmh), allergies, medications, events, active problems, vital signs (vs), level of consciousness (loc), iv access, and treatments given. then, ems and ed staff rated their perception of transfer on a - rating scale. results: ra evaluated patient transfers ( medical and trauma). transfer time did not differ, . minutes for medical ( % ci: . - . ), . minutes for trauma patients ( % ci: . - . )(p = . ). missing data between the two groups also did not differ, except loc and treatment were missed more in medical transfers, while pmh was missed more in the trauma transfers. comparing the transfers with all vs present ( %, / ) and all vs missing ( %, / ), with all vs missing, there was no difference in perception of transfer for ems ( . / vs present vs . / vs absent) or ed staff ( . / vs present, . / vs absent). when all vital signs were missing, ra rated . % of transfers as poor, whereas when all vs were present . % of transfers were considered good. conclusion: ems and ed staff felt transfers of care were professional, teams were attentive, and had similar amounts of interruptions for both medical and trauma cases. their perception of transfer of care was similar even when key information was missing, although external observers rated a significant amount of transfers poorly. thus, ems and ed staffs were not able to evaluate their own performance in a transfer of care and external observers were found to be better evaluators of transfers of care. swati singh, john brown, prasanthi ramanujam ucsf, san francisco, ca background: ems transports a large number of psychiatric emergencies to emergency departments (ed) across the us. research on paramedic education related to behavioral emergencies is sparse, but based on expert opinion we know that gaps in paramedic knowledge and training exist. in our system, paramedics triage patients to medical, detoxification, and purely psychiatric destinations, so a paramedic's understanding of these emergencies directly affects the flow of patients in our eds. objectives: our objectives were to understand the gaps in current training and develop a targeted curriculum for field providers with a long term goal of appropriately recognizing and triaging subjects to the ed. methods: data were collected using a survey that was distributed during a paramedic association meeting in october . subjects were excluded if they did not complete the survey. survey questions addressed demographics of paramedics, frequency of various psychiatric emergencies and their confidence in managing these emergencies. data were collated, analyzed, and presented as descriptive statistics. results: forty-nine surveys were distributed with a response rate of % (n = / ). of the respondents, % (n = ) were male and % (n = ) had at least five years experience. mood, thought, and cognitive disorders were the most frequently encountered presentations and % (n = ) of respondents came across psychiatric emergencies multiple times a week. many respondents did not feel confident managing agitated delirium (n = , %), acute psychosis (n = , %), and intimate partner or elder abuse (n = , %). a third to a half of the respondents felt they have little or no training in chemical sedation (n = , %), verbal de-escalation (n = , %), and triaging patients (n = , %). conclusion: we identified a need for a revised curriculum on management of psychiatric emergencies. future steps will focus on development of a curriculum and change in knowledge after implementation of this curriculum. background: prehospital endotracheal intubation has long been a cornerstone of resuscitative efforts for critically ill or injured patients. paramedic airway management training will need to be modified due to the acc/aha guidelines to ensure maintenance of competency in overall management of airway emergencies. how best to modify the training of paramedics requires an understanding of current experience. objectives: the purpose of this report is to characterize the airway management expertise of experienced and non-experienced paramedics in a single ems system. methods: we retrospectively reviewed all prehospital intubations from an urban/suburban ambulance service (professional ambulance, inc.) over a five-year period (january , to december , ). characteristics of airway management by paramedics with - years of experience (group ) were compared to those with greater than years of experience (group ). airway management was guided by massachusetts statewide treatment protocols governing direct laryngoscopy and all adjunctive approaches. attempts are characterized by laryngoscope blade passing the lips. difficult and failed airways were managed with extraglottic devices (egd) or needle cricothyroidotomy. we reviewed patient characteristics, intubation methods, rescue techniques, and adverse events. results: patients required airway management: ( %) were performed by group and ( %) were performed by group . group was both faster to intubate ( . vs . attempts, p = . ) and less likely to use a rescue device ( . % vs . %, p = . ). both are equally likely to go directly to a rescue device ( % vs %, p = . ). all patients were successfully oxygenated and ventilated with either an endotracheal tube or egd. no surgical airways were performed and no patients died as a result of a failed airway. conclusion: while intubation success rates of paramedics with less than and greater than five years of experience are similar, less experienced paramedics use fewer attempts and are less likely to use a rescue device. both recognize difficult airways and go directly to rescue devices equally. this highlights difficulties faced maintaining competence. education requirements must be evaluated and redesigned to allow paramedics to maintain competence and emphasize airway management according to the latest resuscitation guidelines. how well do ems - - protocols predict ed utilization for pediatric patients? stephanie j. fessler , harold k. simon , daniel a. hirsh , michael colman emory university, atlanta, ga; grady health systems, atlanta, ga background: the use of emergency medical services (ems) for low-acuity pediatric problems has been well documented. however, it is unclear how accurately general ems dispatch protocols predict the subsequent ed utilization for these patients. objectives: to determine the ed resource utilization rate of pediatric patients categorized as low acuity by - - dispatch protocols and then subsequently transferred to a children's hospital. methods: all transports for pediatric patients from the scene by a large urban general ems provider that were prioritized as low acuity by initial - - dispatch protocols were identified. protocols were based on the national academy of medical priority dispatch system, v . starting on jan , , consecutive cases of patients transported to three pediatric emergency departments (ped) of a large tertiary care pediatric health care system were reviewed. demographics, ped visit characteristics, resource utilization, and disposition were recorded. those patients who received meds other than po antipyretics, had labs other than a strep test, a radiology study, a procedure, or were not discharged home were categorized into the significant ed resource utilization group. results: % of the patients were african american and either had public insurance or self-pay ( %, % respectively). the median age was months ( d- yr). % were female. none of these low-acuity patients were upgraded by ems operators en route. upon arrival to the ped, % of transported patients were classified into the significant utilization group. six of the total patients were admitted, including a y/o requiring emergent intubation, an m/o old with a broken cvl, a y/o with sickle cell pain crisis, and a y/o with altered mental status. the remainder of the significant resource utilization group consisted of children needing procedures, anti-emetics, narcotic pain control, labs, and xrays. conclusion: in this general ems - - system, dispatch protocols for pediatric patients classified as low priority did poorly in predicting subsequent ed utilization with % requiring significant resources. further, ems operators did not recognize a critical child who needed emergent intervention. opportunity exists to refine general ems - - protocols for children in order to more accurately define an ems priority status that better correlates with ultimate needs and resource utilization. the objectives: determine if there is an association between a patient's impression of the overall quality of care and his or her satisfaction with provided pain management. it was hypothesized that satisfaction with pain management would be significantly associated with a patient's impression of the overall quality of care. methods: this was a retrospective review of patient satisfaction survey data initially collected by an urban als ems agency from / / to / / . participants were randomly selected from all patients transported proportional to their paramedic defined acuity; categorized as low, medium, or high with a goal of interviews per month. the proportions of patients sampled from each acuity level were % low, % medium, and % high. patients were excluded if there was no telephone number recorded in the prehospital patient record or they were pronounced dead on scene. all satisfaction questions used a five-point likert scale with ratings from excellent to poor that were dichotomized for analysis as excellent or other. the outcome variable of interest was the patient's perception of the overall quality of care. the main independent variable had patients rate the staff who treated them at the scene on their helping to control or reduce their pain. demographic variables were assessed for potential confounding. results: there were , patients with complete data for the outcome and main independent variable with . % male respondents and an average age of . (sd = . ). overall quality of care was rated excellent by . % of patients while . % rated their pain management as excellent. of patients who rated their pain management as excellent, . % rated overall quality of care as excellent while only . % of patients rated overall quality excellent if pain management was not excellent. when controlling for potential confounding variables, those patients who perceived their pain management to be excellent were . ( % ci . - . ) times more likely to rate their overall quality of care as excellent compared to those with non-excellent perceived pain management. conclusion: patients' perceptions of the overall quality of care were significantly associated with their perceptions of pain management. objectives: the purpose of this study is to determine whether ground-based paramedics could be taught and retain the skills necessary to successfully perform a cricothyrotomy. methods: this retrospective study was performed in a suburban county with a population of , and , ems calls per year. participants were groundbased paramedics in a local ems system who were taught wire-guided cricothyrotomy as part of a standardized paramedic educational update program. as part of the educational program, paramedics were taught wire-guided cricothyrotomy on a simulation model previously developed to train emergency medicine residents. after viewing an instructional video, the participants were allowed to practice using a step checklist. not all of these steps were automatic failures. each paramedic was individually supervised performing a cricothyrotomy on the simulator until successful; a minimum of five simulations was required. retention was assessed using the same -step checklist during annual skills testing, after a minimum of weeks to a maximum of months posttraining. results: a total of paramedics completed both the initial training and reassessment during the time period studied. during the initial training phase, % ( of ) of the paramedics were successful in performing all steps of the wire-guided cricothyrotomy. during the retention phase . % ( of ) retained the skills necessary to successfully perform the wire-guided cricothyrotomy. of the -step checklist, most steps were performed successfully by all the paramedics or missed by only of the paramedics. step # , which involved removing the needle prior to advancing the airway device over the guidewire, was missed by . % ( of ) of the participants. step # was not an automatic failure since most participants immediately self-corrected and completed the procedure successfully. conclusion: paramedics can be taught and can retain the skills necessary to successfully perform a wireguided cricothyrotomy on a simulator. future research is necessary to determine if paramedics can successfully transfer these skills to real patients. helicopter emergency medical services in background: netcare is one of the largest private providers of emergency air medical care in south africa. each hems (helicopter emergency medical service) crew is manned by a physician-paramedic team and is dispatched based on specific medical criteria, time to definitive care, and need for physician expertise. objectives: to describe the characteristics of net-care air medical evacuations in gauteng province and to analyze the role of physicians in patient care and effect on call times. methods: all patients transported by a netcare helicopter over a one year period from january -december were enrolled in the study. injury classifications, demographics, procedures, scene and flight times were collected retrospectively from run sheets. data were described by medians and interquartile intervals. results: a total of patients were transported on flights originating from the netcare gauteng helicopter base. ninety-two percent were traumarelated, with % resulting from motor vehicle accidents. physician expertise was listed % of the time as the indication for air medical response. a total of advanced procedures were performed by physicians on patients, including paralytic-assisted intubations, chest tube placement, and cardiac pacing. the median total call time was minutes with minutes spent on scene, compared with and minutes when advanced procedures were performed by hems (p < . ). conclusion: trauma accounts for an overwhelming majority of patients requiring emergency air medical transportation. advanced medical procedures were performed by physicians in nearly a quarter of the patients. there were significant differences in call times when advanced procedures were performed by hems. objectives: we sought to evaluate the level of awareness and adoption of the off-line protocol guidelines by utah ems agencies. methods: we surveyed all ems agencies in utah months after protocol guideline release. medical directors, ems captains, or training coordinators completed a short phone survey regarding their knowledge of the emsc protocol guidelines, and whether their agency had adopted them. in particular, participants were asked about the pain protocol guideline and their management of pediatric pain. results: of the agencies, participated in the survey ( %). of those participating, agencies ( %) were excluded from the analysis: ( %) who only treat adults and ( %) who do not participate in electronic data entry. of the remaining agencies ( %), ( %) were familiar with the utah emsc protocol guidelines; agencies ( %) have either partially or fully adopted the protocol guidelines. agencies ( %) were familiar with the pain treatment protocol guideline; ( %) had adopted it; ( %) planned to either partially or fully adopt the protocol. overall, agencies ( %) had offline protocols allowing the administration of narcotics to children. of those, ( %) had intranasal fentanyl as an available medication and delivery route. of the agencies with offline protocols for pain, ( %) reported familiarity with the emsc pain protocol guideline. conclusion: the creation and dissemination of statewide emsc protocol guidelines results in widespread awareness ( %) and to date % of agencies have adopted them. future investigation into factors associated with protocol adoption should be explored. background: intranasal (in) naloxone is safe and effective for the treatment of opioid overdose. while it has been extensively studied in the out-of-hospital environment in the hands of paramedics and lay people, we are unaware of any studies evaluating the safety and efficacy of in naloxone administration by bls providers. in recent years in naloxone has been added to the bls armamentarium; however, most services/states require an als unit be dispatched and attempt an intercept if in naloxone is administered by the bls providers. objectives: the purpose of this study is to evaluate the safety and effectiveness of bls-administered in naloxone in an urban environment. methods: retrospective cohort review as part of the ongoing qa process of all patients who had in naloxone administration by bls providers. the study was part of a special projects waiver by massachusetts oems from february through november in a busy urban tiered ems system in the metro-boston area. exclusion criteria: cardiac arrest. demographic information was collected, as well as vital signs, number of naloxone doses by bls, patient response to bls naloxone administration (clinical improvement in mental status and/or respiratory status), als intercept. descriptive statistics and confidence intervals are reported using microsoft excel and spss . . results: fifty-six cases of bls-administered in naloxone were identified, and were excluded as cardiac arrests. the included cases had a mean age of . years ± . (range - ), and % (ci - ) were male. of the included cases, % (ci - ) of patients responded to bls administration of naloxone. of the responders, % (ci - ) required two doses. there were protocol violations representing % (ci . - . ) of the total administrations, however in % of these protocol violations the patients had a positive response to the administration of in naloxone. seven of the protocol violations were patients who required a second mg dose of naloxone. eleven cases did not have an als intercept; only of these patients did not respond to bls administration of naloxone. there were no identified adverse events. conclusion: bls providers safely and successfuly administered in naloxone achieving a response rate consistent with studies of als providers' administration of in naloxone. given the success rate of bls providers, it may be feasible for bls to manage responders without the aid of an als intercept. background: an estimated % of patients arriving by ambulance to the ed are in moderate to severe pain. however, the management of pain in the prehospital setting has been shown to be inadequate, and untreated pain may have negative consequences for patients. objectives: to determine if focused education on pediatric pain management and implementation of a pain management protocol improved the prehospital assessment and treatment of pain in adult patients. specifically, this study aimed to determine if documentation of pain scores and administration of morphine by ems personnel improved. methods: this was a retrospective before and after study conducted by reviewing a county-wide prehospital patient care database. the study population included all adult patients transported by ems between february and february with a working assessment of trauma or burn. ems patient care records were searched for documentation of pain scores and morphine administration years before and years after an intensive pediatric focused pain management education program and implementation of a pain management protocol. frequencies and % cis were determined for all patients meeting the inclusion criteria in the before and after time period and chisquare was used to compare frequencies between time periods. a secondary analysis was conducted using only subjects documented as meeting the protocol's treatment guidelines. results: , ( %) of , adult patients transported by ems during the study period met the inclusion criteria: , in the before and , in the after period. subject demographics were similar between the two periods. documentation of pain score did not change between the time periods ( background: there is a presumption that ambulance response times affect patient outcome. we sought to determine if shorter response times really make a difference in hospital outcomes. objectives: to determine if ambulance response time makes a difference in the outcomes of patients transported for two major trauma (motor vehicle crash injuries, penetrating trauma) and two major medical (difficulty breathing and chest pain complaints) emergencies. methods: this study was conducted in a metropolitan ems system serving a population total of , including urban and rural areas. cases were included if the private ems service was the first medical provider on scene, the case was priority , and the patient was years and older. a -month time period was used for the data evaluation. four diagnoses were examined: motor vehicle crash injuries, penetrating trauma, difficulty breathing, and chest pain complaints. ambulance response times were assessed for each of the four different complaints. the patients' initial vital signs were assessed and the number of vital signs out of range was recorded. a sampling of all cases which went to the single major trauma center was selected for evaluation of hospital outcome. using this hospital sample, number of vital signs out of range were assessed as a surrogate marker indicating severity of hospital outcome. correlation coefficients were used to evaluate interactions between independent and outcome variables. results: of the cases we reviewed over the month period, we found that the ems service responded significantly faster to trauma complaints at . minutes (n = ) than medical complaints at . minutes (n = ) . in the hospital sample of cases, number of vital signs out of range were positively correlated with hospital days (r = . ), admits (r = . ), icu admits (r = . ), and deaths (r = . ), but not response times (r = (-) . ). in the entire sample, there was no correlation between vital signs out of range and response times for any diagnosis (see figure) . conclusion: conclusions: based on our hospital sample which showed that number of vital signs out of range was a surrogate marker of worse hospital outcomes, we find that hospital outcomes are not related to initial response times. adverse effects following prehospital use of ketamine by paramedics eric ardeel baylor college of medicine, houston, tx background: ketamine is widely used across specialties as a dissociative agent to achieve sedation and analgesia. emergency medical services (ems) use ketamine to facilitate intubation and pain control, as well as to sedate acutely agitated patients. published studies of ems ketamine practice and effects are scarce. objectives: describe the incidence of adverse effects occurring after ketamine administration by paramedics treating under a single prehospital protocol. methods: a retrospective analysis was conducted of consecutive patients receiving prehospital ketamine from paramedics in the suburban/rural ems system of montgomery county hospital district, texas between august , and october , . ketamine administration indications were: need for rapid control of violent/agitated patients requiring treatment and transport; sedation and analgesia after trauma; facilitation of intubation and mechanical ventilation. ketamine administration contraindications were: equivalent ends achieved by less invasive means; hypertensive crisis; angina; signs of significantly elevated intracranial pressure; anticipated inability to support or control airway. all patients were included, regardless of indication for ketamine administration. data were abstracted from electronic patient care records and available continuous physiologic monitoring data, and analyzed for the presence of adverse effects as defined a priori in ''clinical practice guidelines for emergency department ketamine dissociative sedation: update.'' results: no patients were identified as experiencing adverse effects as defined by the referenced literature. ketamine was utilized most often for patients with the following nemsis provider's primary impression: ( %) altered level of consciousness, ( %) behavioral/psychiatric, ( %) traumatic injury. overall, combativeness was associated with ( %) patients. the mean age was years (range - years) and ( %) were male. the mean ketamine dose was mg (range - mg) and twenty-four ( %) patients received multiple administrations. conclusion: in this patient population, our data indicate that prehospital ketamine use by ems paramedics, across all indications for administration, was safe. further study of ketamine's utility in ems is warranted. an background: rigorous evaluation of the effect of implementing nationally vetted evidence-based guidelines (ebgs) has been notoriously difficult in ems. specifically, human subjects issues and the health insurance portability and accountability act (hipaa) present major challenges to linking ems data with distal outcomes. objectives: to develop a model that addresses the human subjects and hipaa issues involved with evaluating the effect of implementing the traumatic brain injury (tbi) ebgs in a statewide ems system. methods: the excellence in prehospital injury care (epic) project is an nih-funded evaluation of the effect of implementing the ems tbi guidelines throughout arizona (ninds- r ns - a ). to accomplish this, a partnership was developed between the arizona department of health services (adhs), the university of arizona, and more than ems agencies that serve approximately % of the state's population. results: ebg implementation: implementation follows all routine regulatory processes for making changes in ems protocols. in arizona, the entire project must be carried out under the authority of the adhs director. evaluation: a before-after system design is used (randomization is not acceptable). hipaa: as an adhsapproved public health initiative, epic is exempt from hipaa, allowing sharing of protected health information between participating entities. for epic, the state attorney general provided official verification of hi-paa exemption, thus allowing direct linkage of ems and hospital data. irb: once epic was officially deemed a public health initiative, the university irb process was engaged. as an officially sanctioned public health project, epic was determined to not be human subjects research. this allows the project to implement and evaluate the effect of this initiative without requiring individual informed consent. conclusion: by utilizing an ems-public health-university partnership, the ethical and regulatory challenges related to evaluating implementation of new ebgs can be successfully overcome. the integration of the department of health, the attorney general, and the university irb can properly protect citizens while permitting efficient implementation and rigorous evaluation of the effect of ebgs. this novel approach may be useful as a model for evaluation of implementing ems ebgs in other states and large counties. ( . %- . % by age) were transported to non-trauma centers. the most common reasons cited by ems for hospital selection were: patient preference ( . %), closest facility ( . %), and specialty center ( . %). patient preference increased with age (p for trend . ) and paralleled under-triage ( figure ). iss ‡ patients transported to non-trauma hospitals by patient request had lower unadjusted mortality ( . %, %ci . - . ) than similar patients transported to trauma centers ( . %, %ci . - . ) or transported for other reasons ( . %, %ci . - . ) (figure ) . under-triage appears to be influenced by patient preference and age. self-selection for transport to non-trauma centers may result in under-triaged patients with inherently better prognosis than triagepositive patients. background: only % of all out-of-hospital cardiac arrest (ohca) patients receive bystander cpr (cardiopulmonary resuscitation). the neighborhood in which an ohca occurs has significant influence on the likelihood of receiving bystander cpr. objectives: to utilize geographic information systems to identify ''high-risk'' neighborhoods, defined as census tracts with high incidence of ohca and low cpr prevalence. methods: design: secondary analysis of the cardiac arrest registry to enhance survival (cares) dataset for denver county, colorado. population: all consecutive adults (> years old) with ohca due to cardiac etiology from january , through december , . data analysis: analyses were conducted in arc-gis. three spatial statistical methods were used: local morans i (lmi), getis-ord gi*(gi*), and spatial empirical bayes (seb) adjusted rates. census tracts with high incidence of ohca, as identified by all three spatial statistical methods, were then overlain with low bystander cpr census tracts, which were identified in at least two out of three statistical methods (lmi, gi*, or the lowest quartile of bystander cpr prevalence). overlapping census tracts identified with both high ohca incidence and low cpr prevalence were designated as ''highrisk''. results: a total of arrests in census tracts occurred during the study period, with arrests included in final sample. events were excluded if they were unable to be geocoded (n = ), outside denver county (n = ), or occurred in a jail (n = ), hospital/ physician's office (n = ), or nursing home (n = ). for high ohca incidence: lmi identified census tracts, gi* identified census tracts, and the seb method identified census tracts. twenty-five census tracts were identified by all three methods. for low bystander cpr prevalence: lmi identified census tracts, gi* identified census tracts, and census tracts were identified as being in the lowest quartile of cpr prevalence. twenty-four census tracts were identified by two of the three methods. two census tracts were identified as high-risk having both high ohca incidence and low cpr prevalence (figure) . high-risk census tract demographics as compared to denver county are shown in the table. conclusion: the two high-risk census tracts, comprised of minority and low-income populations, appear to be possible sites for targeted community-based cpr interventions. objectives: we sought to assess the accuracy and correlation of geographic information system (gis) derived transport time compared to actual ems transport time in ohca patients. methods: prospective, observational cohort analysis of ohca patients in vancouver, b.c., one of the sites of the resuscitation outcomes consortium (roc). a random sample from all of the ohca cases from / through / was selected for analysis from one site of the roc epistry. using gis, ems transport time was derived from reported latitude/longitude coordinates of the ohca event to the actual receiving hospital. this was calculated via the actual network distance using arcgis. this gis-derived time was then compared to the actual ems transport time (in minutes) using the wilcoxon signed rank test. scatter plot analysis of actual vs. gis times were created to evaluate the relationship between actual and calculated time. a linear regression model predicting actual ems transport time from the derived gis-time was also developed in order to examine the potential relationship between the two variables. differences in the relationship were also investigated based on time of the day to reflect varying traffic conditions. results: cases were randomly selected for analysis. the median actual transport time was significantly longer than the median gis derived transport time ( . minutes vs. . minutes). scatter plot analysis did not reveal any significant correlation between actual and gis-based time. additionally, there was poor approximation of gis-based time and actual ems time (r = . ) with no evidence of a significant linear relationship between the two. the poorest correlation of time was observed during the morning hours ( : - : ; r = . ) while the strongest correlation was during the overnight hours ( : - : ; r = . ). conclusion: gis derived time does not appear to correlate well with actual ems transport time of ohca patients. efforts should be made to accurately obtain actual ems transport times for ohca patients. objectives: we first sought to describe the incidence of ohca presenting to the ed. we then sought to determine the association between hospital characteristics and survival to hospital admission. methods: we identified patients with diagnoses of cardiac arrest or ventricular fibrillation (icd- . or . ) in the nationwide emergency department sample, a nationally representative estimate of all ed admissions in the us. eds reporting ‡ patient with ohca were included. our primary outcome was survival to hospital admission. we examined variability in hospital survival rate and also classified hospitals into high or low performers based on median survival rate. we used this dichotomous hospital level outcome to examine factors associated with survival to admission including hospital and patient demographics, ed volume, cardiac arrest volume, and cardiac catheterization availability. all unadjusted and adjusted analyses were performed using weighted statistics and logistic regressions. results: of the hospitals, ( . %) were included. in total, , cases of cardiac arrest were identified, representing an estimated , cases nationally. overall ed ohca survival to hospital admission was . % (iqr . %, . %) in adjusted analyses, increased survival to admission was seen in hospitals with teaching status (or . , % ci . - . , p < . ), annual ed visits ‡ , (or . , % ci . - . , p < . ), and pci capability (or . , % ci . - . , p = . ). in separate adjusted analyses including teaching status and pci capabilities, hospitals with > annual cardiac arrest cases (or . , % ci . - . , p < . ) were also shown to have improved survival (figure) . conclusion: ed volume, cardiac arrest volume, and pci capability were associated with improved survival to hospital admission in patients presenting to the ed after ohca. an improved understanding of the contribution of ed care to ohca survival may be useful in guiding the regionalization of cardiac arrest care. background: prior investigations have demonstrated regional differences in out-of-hospital cardiac arrest (ohca) outcomes, but none have evaluated survival variability by hospital within a single major us city. objectives: we hypothesized that -day survival from ohca would vary considerably among one city's receiving hospitals. methods: we performed a retrospective review of prospectively collected cardiac arrest data from a large, urban ems system. our population included all ohcas with a recorded social security number (which we used to determine -day survival through the social security death index) that were transported to a hospital between / / and / / . we excluded traumatic arrests, pediatric arrests, and hospitals receiving less than ohcas with social security numbers over the three-year study period. we examined the associa-tion between receiving hospital and -day survival. additional variables examined included: level i trauma center status, teaching hospital status, ohca volume, and whether post-arrest therapeutic hypothermia (th) protocols were in place in . statistics were performed using chi-square tests and logistic regression. results: our study population comprised arrest cases delivered to unique hospitals with an overall -day survival of . %. mean age was . (sd . ) years. males comprised . % of the cohort; . % of victims were black. thirty-day survival varied significantly among the hospitals, ranging from . % to . % (chi-square . , p = . ). ohcas delivered to level i trauma centers were significantly more likely to survive ( . % vs. . %, p = . ), as were those delivered to hospitals known to offer post-arrest th ( . % vs. . %, p = . ). hospital teaching status and ohca volume were not associated with survival. conclusion: there was significant variability in ohca survival by hospital. patients were significantly more likely to survive if transported to a level i trauma center or hospital with post-arrest th protocols, suggesting a potential role for regionalization of ohca care. limiting our population to ohcas with recorded social security numbers reduced our power and may have introduced selection bias. further work will include survival data on the complete set of ohcas transported to hospitals during the three-year study period. background: traumatic brain injury is a leading cause of death and disability. previous studies suggest that prehospital intubation in patients with tbi may be associated with mortality. limited data exist comparing prehospital (ph) nasotracheal (nt), prehospital orotracheal (ot), and ed ot intubation and mortality following tbi. objectives: to estimate the associations between ph nt, ph ot, and ed ot intubation and in-hospital mortality in patients with moderate to severe tbi, with hypotheses that ph nt and ph ot intubation would be associated with increased mortality when compared to ed ot or no intubation. methods: an analysis using the denver health trauma registry, a prospectively collected database. consecutive adult trauma patients from - with moderate to severe tbi defined as head abbreviated injury scale (ais) scores of - . structured chart abstraction by blinded physicians was used to collect demographics, injury and prehospital care characteristics, intubation status and timing, in-hospital mortality and survival time, and neurologic function at discharge. poor neurologic function was defined as cerebral performance category score of - . multivariable logistic regression and survival analyses were performed, using multiple imputation for missing data. results: of the , patients, the median age was (iqr - ) years. the median ph gcs was (iqr - ), median injury severity score was (iqr - ), and median head ais was (iqr - ). ph nt occurred in . %, ph ot in . %, and ed ot in . %, while mortality occurred in . %. the -, -, and -hour survival analyses are outlined in the table. survival curves for ph nt, ph ot, and ed ot are demonstrated in the figure (p < . ) . conclusion: prehospital intubation in patients with moderate to severe tbi is associated with increased mortality. contrary to our initial hypothesis, there was also a significant association between ed intubation and mortality. these associations persisted despite survival time, and while adjusting for injury severity. background: sbdp is a breakdown product of the cytoskeletal protein alpha-ii-spectrin found in neurons and has been detected in severe tbi. objectives: this study examined whether early serum levels of sbdp could distinguish: ) mild tbi from three control groups; ) those with and without traumatic intracranial lesions on ct (+ct vs -ct); and ) those having a neurosurgical intervention (+nsg vs -nsg) in mild and moderate tbi (mmtbi). methods: this prospective cohort study enrolled adult patients presenting to two level i trauma centers following mmtbi with blunt head trauma with loss of consciousness, amnesia, or disorientation and a gcs - . control groups included uninjured controls and trauma controls presenting to the ed with orthopedic injuries or an mvc without tbi. mild tbi was defined as gcs and moderate tbi as having a gcs < . blood samples were obtained in all patients within hours of injury and measured by elisa for sbdp (ng/ml). the main outcomes were: ) the ability of sbdp to distinguish mild tbi from three control groups; ) to distinguish +ct from -ct and; ) to distinguish +nsg from -nsg. data were expressed as means with %ci, and performance was tested by roc curves (auc and %ci). results: there were patients enrolled: tbi patients ( gcs , gcs - ), trauma controls ( mvc controls and orthopedic controls), and uninjured controls. the mean age of tbi patients was years (range - ) with % males. fourteen ( %) had a +ct and % had +nsg. mean serum sbdp levels were . ( %ci . - . ) in normal controls, . ( . - . ) in orthopedic controls, . ( . - . ) in mvc controls, . ( . - . ) in mild tbi with gcs , and . ( . - . ) in tbi with gcs - (p < . ). the auc for distinguishing mild tbi from both controls was . ( %ci . - . ). mean sbdp levels in patients with -ct versus +ct were . ( . - . ) and . ( . - . ) respectively (p < . ) with auc = . ( %ci . - . ). mean sbdp levels in patients with -nsg versus +nsg were . ( . - . ) and . ( . - . ) respectively (p < . ) with auc = . ( %ci . - . ). conclusion: serum sbdp levels were detectable in serum acutely after injury and were associated with measures of injury severity including ct lesions and neurosurgical intervention. further study is required to validate these findings before clinical application. utility of platelet background: pre-injury use of anti-platelet agents (e.g., clopidogrel and aspirin) is a risk factor for increased morbidity and mortality in patients with traumatic intracranial hemorrhage (tich). some investigators have recommended platelet transfusion to reverse the anti-platelet effects in tich. objectives: this evidence-based medicine review examines the evidence regarding the effect of platelet transfusion in emergency department (ed) patients with pre-injury anti-platelet use and tich on patientoriented outcomes. methods: the medline, embase, cochrane library, and other databases were searched. studies were selected for inclusion if they compared platelet transfusion to no platelet transfusion in the treatment of adult ed patients with pre-injury anti-platelet use and tich, and reported rates of mortality, neurocognitive function, or adverse effects as outcomes. we assessed the quality of the included studies using ''grading of recommendations assessment, development and evaluation'' (grade) criteria. categorical data are presented as percentages with % confidence interval (ci). relative risks (rr) are reported when clinically significant. results: five retrospective, registry-based studies were identified, which enrolled patients cumulatively. based on standard criteria, three studies were of ''low'' quality evidence and two studies had ''very low'' qualities. one study reported higher in-hospital mortality in patients with platelet transfusion (ohm et al), another showed a lower mortality rate in patients receiving platelet transfusion (wong et al). three studies did not show any statistical difference in comparing mortality rates between the groups (table) . no studies reported intermediate-or long-term neurocognitive outcomes or adverse events. conclusion: five retrospective registry studies with suboptimal methodologies provide inadequate evidence to support the routine use of platelet transfusion in adult ed patients with pre-injury anti-platelet use and tich. abnormal levels of end-tidal carbon dioxide (etco ) are associated with severity of injury in mild and moderate traumatic brain injury (mmtbi) linda papa , artur pawlowicz , carolina braga , suzanne peterson , salvatore silvestri orlando regional medical center, orlando, fl; university of central florida, orlando, fl background: capnography is a fast, non-invasive technique that is easily administered and accurately measures exhaled etco concentration. etco levels respond to changes in ventilation, perfusion, and metabolic state, all of which may be altered following tbi. objectives: this study examined the relationship between etco levels and severity of tbi as measured by clinical indicators including glasgow coma scale (gcs) score, computerized tomography (ct) findings, requirement of neurosurgical intervention, and levels of a serum biomarkers of glial damage. methods: this prospective cohort study enrolled adult patients presenting to a level i trauma center following a mmtbi defined by blunt head trauma followed by loss of consciousness, amnesia, or disorientation and a gcs - . etco measurements were recorded from the prehospital and emergency department records and compared to indicators of tbi severity. results: of the patients enrolled, ( %) had a normal etco level and ( %) had an abnormal etco level. the mean age of enrolled patients was (range - ) and ( %) were male. mechanisms of injury included motor vehicle collision in ( %), motor cycle collision in ( %), fall in ( %), bicycle/ pedestrian struck in ( %), and other in ( %). eight ( %) patients had a gcs - and ( %) had a gcs - . of the ( %) patients with intracranial lesions on ct, ( %) had an abnormal etco level (p = . ). of the ( %) patients who required a neurosurgical intervention, % had an abnormal etco level (p = . ). levels of a biomarker indicative of astrogliosis were significantly higher in those with abnormal etco compared to those with a normal etco (p = . ). conclusion: abnormal levels of etco were significantly associated with clinical measures of brain injury severity. further research with a larger sample of mmtbi patients will be required to better understand and validate these findings. background: acetaminophen (apap) poisoning is the most frequent cause of acute hepatic failure in the us. toxicity requires bioactivation of apap to toxic metabolites, primarily via cyp e . children are less susceptible to apap toxicity; one current theory is that children's conjugative pathway (sulfonation) is more active. liquid apap preparations contain propylene glycol (pg), a common excipient that inhibits apap bioactivation and reduces hepatocellular injury in vitro and in rodents. cyp e inhibition may decrease toxicity in children, who tend to ingest liquid apap preparations, and suggests a potential novel therapy. objectives: to compare phase i (toxic) and phase ii (conjugative) metabolism of liquid versus solid prepara-tions of apap. we hypothesize that ingestion of a liquid apap preparation results in decreased production of toxic metabolites relative to a solid preparation, likely due to the presence of pg in the liquid preparations. methods: design-pharmacokinetic cross-over study. setting-university hospital clinical research center. subjects-adults ages - taking no chronic medications. interventions-subjects were randomized to receive a mg/kg dose of a commercially available solid or liquid apap preparation. after a washout period of greater than week, subjects received the same dose of apap in the alternate preparation. apap, apap-glucuronide and apap-sulfate (phase metabolites), apap-cysteinate and apap-mercapturate (phase metabolites) were analyzed via lc/ms in plasma over hours. peak concentrations and measured auc were compared using paired-sample t-tests. plasma pg levels were measured. results: fifteen subjects completed the protocol. peak concentrations and aucs of the cyp e derived toxic metabolites were significantly lower following ingestion of the liquid preparation (table, figure) . the glucuronide and sulfate metabolites were not different. pg was present following ingestion of liquid but not solid preparations. conclusion: ingestion of liquid relative to solid preparations in therapeutic doses results in decreased plasma levels of toxic apap metabolites. this may be due to inhibition of cyp e by pg, and may explain the decreased susceptibility in children. a less hepatotoxic formulation of apap can potentially be developed if co-formulated with a cyp e inhibitor. background: pressure immobilization bandages have been shown to delay mortality for up to hours after coral snake envenomation, providing an inexpensive and effective treatment when antivenin is not readily available. however, long-term efficacy has not been established. objectives: determine if pressure immobilization bandages, consisting of an ace wrap and splint, can delay morbidity and mortality from coral snake envenomation, even in the absence of antivenin therapy. methods: institutional animal care and use committee approval was obtained. this was a randomized, observational pilot study using a porcine model. ten pigs ( . kg to . kg) were sedated and intubated for hours. pigs were injected subcutaneously in the left distal foreleg with mg of lyophilized m. fulvius venom resuspended in water, to a depth of mm. pigs were randomly assigned to either a control group (no compression bandage and splint) or a treatment group (compression bandage and splint) approximately minute after envenomation. pigs were monitored daily for days for signs of respiratory depression, decreased oxygen saturations, and paresis/paralysis. in case of respiratory depression, pigs were euthanized and time to death recorded. chi-square was used to compare rates of survival up to days and a kaplan-meier survival curve constructed. results: average survival time of control animals was ± minutes compared to , ± , minutes for treated animals. significantly more pigs in the treatment group survived to hours than in the control group (p = . ). two of the treatment pigs survived to the endpoint of days, but showed necrosis of the distal lower extremity. conclusion: long-term survival after coral snake envenomation is possible in the absence of antivenin with the use of pressure immobilization bandages. the applied pressure of the bandage is critical to allowing survival without secondary consequences (i.e. necrosis) of envenomation. future studies should be designed to accurately monitor the pressures applied. background: patients exposed to organophosphate (op) compounds demonstrate a central apnea. the kölliker-fuse nuclei (kf) are cholinergic nuclei in the brainstem involved in central respiratory control. objectives: we hypothesize that exposure of the kf is both necessary and sufficient for op-induced central apnea. methods: anesthetized and spontaneously breathing wistar rats (n = ) were exposed to a lethal dose of dichlorvos using three experimental models. experiment (n = ) involved systemic op poisoning using subcutaneous (sq) dichlorvos ( mg/kg or x ld ). experiment (n = ) involved isolated poisoning of the kf using stereotactic microinjections of dichlorvos ( micrograms in microliters) into the kf. experiment (n = ) involved systemic op poisoning with isolated protection of the kf using sq dichlorvos ( mg/kg) and stereotactic microinjections of organophosphatase a (opda), an enzyme that degrades dichlorvos. respiratory and cardiovascular parameters were recorded continuously. histological verification of injection site was performed using kmno injections. animals were followed post-poisoning for hour or death. betweengroup comparisons were performed using a repeated measured anova or student's t-test where appropriate. results: animals poisoned with sq dichlorvos demonstrated respiratory depression starting . min post exposure, progressing to apnea . min post exposure. there was no difference in respiratory depression between animals with sq dichlorvos and those with dichlorvos microinjected into the kf. despite differences in amount of dichlorvos ( mg/kg vs . mg/kg) and method of exposure (sq vs cns microinjection), min following dichlorvos both groups (sq vs microinjection respectively) demonstrated a similar percent decrease in respiratory rate ( . vs . , p = . ), minute ventilation ( background: patients sustaining rattlesnake envenomation often develop thrombocytopenia, the etiology of which is not clear. laboratory studies have demonstrated that venom from several species, including the mojave rattlesnake (crotalus scutulatus scutulatus), can inhibit platelet aggregation. in humans, administration of crotaline fab antivenom (av) has been shown to result in transient improvement of platelet levels; however, it is not known whether platelet aggregation also improves after av administration. objectives: to determine the effect of c. scutulatus venom on platelet aggregation in vitro in the presence and absence of crotaline fab antivenom. methods: blood was obtained from four healthy male adult volunteers not currently using aspirin, nsaids, or other platelet-inhibiting agents. c. scutulatus venom from a single snake with known type b (hemorrhagic) activity was obtained from the national natural toxins research center. measurement of platelet aggregation by an aggregometer was performed using five standard concentrations of epinephrine (a known platelet aggregator) on platelet-rich plasma over time, and a mean area under the curve (auc) was calculated. five different sample groups were measured: ) blood alone; ) blood + c. scutulatus venom ( . mg/ml); ) blood + crotaline fab av ( mg/ml); ) blood + venom + av ( mg/ ml); ) blood + venom + av ( mg/ml). standard errors of the mean (sem) were calculated for each group. results: antivenom administration by itself did not significantly affect platelet aggregation compared to baseline ( . ± . %, p = . ). administration of venom decreased platelet aggregation ( . ± . %, p < . ). concentrated av administration in the presence of venom normalized platelet aggregation ( . ± . %) and in the presence of diluted av significantly increased aggregation ( . ± . %); p < . for both groups when compared to the venom-only group. to control for the effects of the venom and av, each was run independently in platelet-rich plasma without epinephrine; neither was found to significantly alter platelet aggregation. conclusion: crotaline fab av improved platelet aggregation in an in vitro model of platelet dysfunction induced by venom from c. scutulatus. the mechanism of action remains unclear but may involve inhibition of venom binding to platelets or a direct action of the antivenom on platelets. background: routine use of both breathalyzers and hand sanitizers is common across emergency depart-ments. the most common hand sanitizer on the market, purell, contains % ethyl alcohol and a lesser amount of isopropyl alcohol. previous investigations have documented that risk is low to the health care worker who applies frequent hand sanitizers to themselves. however, it is unknown whether this alcohol mixture causes false readings on a breathalyzer machine being used to determine alcohol levels on others. objectives: to determine the effect on the measurement of breathalyzer readings in individuals who have not consumed alcohol after hand sanitizer is applied to the experimenter holding a breathalyzer machine. methods: after obtaining informed consent, a breathalyzer reading was obtained in participants who had not consumed any alcohol in the last hours. three different experiments were performed with different participants in each. in experiment , two pumps of hand sanitizer were applied to the experimenter. without allowing the sanitizer to dry, the experimenter then measured the breathalyzer reading of the participant. in experiment , one pump of sanitizer was applied to the experimenter. measurements of the participant were taken without allowing the sanitizer to dry. in experiment , one pump of sanitizer was placed on the experimenter and rubbed until dry according to the manufacturer's recommendations. readings were recorded and analyzed using paired t-tests. results: the initial breathalyzer reading for all participants was . after two pumps of hand sanitizer were applied without drying (experiment ), breathalyzers ranged from . to . , with a mean above the legalintoxication limit of . (t( ) = ) . , p < . ). after one pump of hand sanitizer was applied without drying (experiment ), breathalyzers ranged from . to . , with a mean of . (t( ) = ) . , p < . ). after one pump of hand sanitizer was applied according to manufacturer's directions (experiment ), breathalyzers ranged from . to . with a mean of . (t( ) = ) . , p < . ). conclusion: use of hand sanitizer according to the manufacturer's recommendations results in a small but significant increase in breathalyzer readings. however, the improper and overuse of common hand sanitizer elevates routine breathalyzer readings, and can mimic intoxication in individuals who have not consumed alcohol. stephanie carreiro, jared blum, francesca beaudoin, gregory jay, jason hack objectives: the primary aim of this study is to determine if pretreatment with ile affects the hemodynamic response to epinephrine in a rat model. hemodynamic response was measured by a change in heart rate (hr) and mean arterial pressure (map). we hypothesized that ile would limit the rise in map and hr that typically follow epinephrine administration. methods: twenty male sprague dawley rats (approximately - weeks of age) were sedated with isoflurane and pretreated with a ml/kg bolus of ile or normal saline, followed by a mcg/kg dose of epinephrine intravenously. intra-arterial blood pressure and hr were monitored continuously until both returned to baseline (biopaq). a multifactorial analysis of variance (manova) was performed to assess the difference in map and hr between the two groups. standardized t-tests were then used to compare the peak change in map, time to peak map, and time to return to baseline map in the two groups. results: overall, a significant difference was found between the two groups in map (p = . ) but not in hr (p = . ). there was a significant difference (p = . ) in time to peak map in the ile group ( sec, % ci - ) versus the saline group ( sec, % ci - ) and a significant difference (p = . ) in time to return to baseline map in ile group ( sec, % ci - ) versus the saline group ( sec, % ci - ). there was no significant difference (p = . ) in the peak change in map of the ile group ( . , mmhg, % ci - ) versus the saline group ( . mmhg, % ci - ). conclusion: our data show that in this rat model ile pretreatment leads to a significant difference in map response to epinephrine, but no difference in hr response. ile delayed the peak effect and prolonged the duration of effect on map but did not alter the peak increase in map. this suggests that the use of ile may delay the time to peak effect of epinephrine if the drugs are administered concomitantly to the same patient. further research is needed to explore the mechanism of this interaction. rasch analysis of the agitation severity scale when used with emergency department acute psychiatry patients tania d. strout, michael r. baumann maine medical center, portland, me background: agitation is a frequently observed and problematic phenomenon in mental health patients being treated in the emergency setting. the agitation severity scale (agss), a reliable and valid instrument, was developed using classical test theory to measure agitation in acute psychiatry patients. objectives: the aim of this study was to analyze the agss according to the rasch measurement model and use the results to determine whether improvements to the instrument could be made. methods: this prospective, observational study was irb-approved. adult ed patients with psychiatric chief complaints and dsm-iv-tr diagnoses were observed using the agss. the rasch rating scale model was employed to evaluate the items comprising the agss using winsteps statistical software. unidimensionality, item fit, response category performance, person and item separation reliability, and hierarchical ordering of items were all examined. a principle components analysis (pca) of the rasch residuals was also performed. results: variable maps revealed that all of the agss items were used to some degree and that the items were ordered in a way that makes clinical sense. several duplicative items, indicating the same degree of agitation, were identified. item ( . ) and person ( . ) separation statistics were adequate, indicating appropriate spread of items and subjects along the agitation continuum and providing support for the instrument's reliability. keymaps indicated that the agss items are functioning as intended. analysis of fit demonstrated no extreme misfitting items. pca of the rasch residuals revealed a small amount of residual variance, but provided support for the agss as being unidimensional, measuring the single construct of agitation. the results of this rasch analysis support the agss as a psychometrically robust instrument for use with acute psychiatry patients in the emergency setting. several duplicative items were identified that may be eliminated and re-evaluated in future research; this would result in a shorter, more clinically useful scale. in addition, a gap in items for patients with lower levels of agitation was identified. generation of additional items intended to measure low levels of agitation could improve clinician's ability to differentiate between these patients. background: attempted suicide is one of the strongest clinical predictors of subsequent suicide and occurs up to times more frequently than completed suicide. as a result, suicide prevention has become a central focus of mental health policy. in order to improve current treatment and intervention strategies for those presenting with suicide attempt and self-injury in the emergency department (ed), it is necessary to have a better understanding of the types of patients who present to the ed with these complaints. objectives: to describe the epidemiology of ed visits for attempted suicide and self-inflicted injury over a year period. methods: data were obtained from the national hospital ambulatory medical care survey (nhamcs). all visits for attempted suicide and self-inflicted injury (e -e ) during - were included. trend analyses were conducted using stata's nptrend (a nonparametric test for trends that is an extension of the wilcoxon rank-sum test) and regression analyses. a two-tailed p < . was considered statistically significant. results: over the -year period, there were an average of , annual ed visits for attempted suicide and self-inflicted injury ( . [ % confidence interval (ci) . - . ] visits per , us population). the overall mean patient age was years, with visits most common among ages - ( . ; %ci . - . ). the average annual number of ed visits for suicide attempt and self-inflicted injury more than doubled from , in - to , in - . during the same timeframe, ed visits for these injuries per , us population almost doubled for males ( . to . ), females ( . to . ), whites ( . to . ), and blacks ( . to . ). no temporal differences were found for method of injury or ed disposition; there was, however, a significant decrease in visits determined by the physician to be urgent/emergent from % in to % in . conclusion: ed visit volume for attempted suicide and self-inflicted injury has increased over the past two decades in all major demographic groups. awareness of these longitudinal trends may assist efforts to increase research on suicide prevention. in addition, this information may be used to inform current suicide and self-injury related ed interventions and treatment programs. benjamin l. bregman, janice c. blanchard, alyssa levin-scherz george washington university, washington, dc background: the emergency department (ed) has increasingly become a health care access point for individuals with mental health needs. recent studies have found that rates of major depression disorder (mdd) diagnosed in eds are far above the national average. we conducted a study assessing whether individuals with frequent ed visits had higher rates of mdd than those with fewer ed visits in order to help guide screening and treatment of depressed individuals encountered in the ed. objectives: this study evaluated potential risk factors associated with mdd. we hypothesized that patients who are frequent ed visitors will have higher rates of mdd. methods: this was a single center, prospective, crosssectional study. we used a convenience sample of noncritically ill, english speaking adult patients presenting with non-psychiatric complaints to an urban academic ed over months in . we oversampled patients presenting with ‡ visits over the previous days. subjects were surveyed about their demographic and other health and health care characteristics and were screened with the phq , a nine-item questionnaire that is a validated, reliable predictor of mdd. we conducted bivariate (chi-square) and multivariate analysis controlling for demographic characteristics using sta-ta v. . . our principal dependent variable of interest was a positive depression screen (phq score ‡ ). our principal independent variable of interest was ‡ visits over the previous days. results: our response rate was . % with a final sample size of . of our total sample, ( . %) had three or greater visits within the prior days. one hundred ( %) frequent visitors had a positive phq mdd screen as compared to ( . %) of subjects with fewer than three visits (p < . ). in our multivariate analysis, the odds for having three or more visits for subjects who had a positive depression screen was . ( . , . ). of subjects with three or more visits with a positive depression screen, only ( %) were actively being treated for mdd at the time of their visit. conclusion: our study found a high prevalence of untreated depression among frequent users of the ed. eds should consider routinely screening patients who are frequent consumers for mdd. in addition, further studies should evaluate the effect of early treatment and follow up for mdd on overall utilization of ed services. access to psychiatric care among patients with depression presenting to the emergency department janice c. blanchard, benjamin l. bregman, dana rosenfarb, qasem al jabr, eun kim george washington university, washington, dc background: literature suggests that there is a high rate of major depressive disorder (mdd) in emergency department (ed) users. however, access to outpatient mental health services is often limited due to lack of providers. as a result, many persons with mdd who are not in active treatment may be more likely to utilize the ed as compared to those who are currently undergoing outpatient treatment. objectives: our study evaluated utilization rates and demographic characteristics associated with patients with a prior diagnosis of mdd not in active treatment. we hypothesized that patients who present to the ed with untreated mdd will have more frequent ed visits. methods: this was a single center, prospective, crosssectional study. we used a convenience sample of noncritically ill, english speaking adult patients presenting with non-psychiatric complaints to an urban academic ed over months in . subjects were surveyed about their demographic and other health and health care characteristics and were screened with the phq , a nine-item questionnaire that is a validated, reliable predictor of mdd. we conducted bivariate (chi-square) and multivariate analysis controlling for demographic characteristics using stata v. . . our principal dependent variable of interest was a positive depression screen (phq ‡ ). our analysis focused on the subset of patients with a prior diagnosis of mdd with a positive screen for mdd during their ed visit. results: our response rate was . % with a final sample size of . ( . %) patients screened positive for mdd with a phq score ‡ . of the patients with a positive depression screen, . % reported a prior history of treatment for mdd (n = ). of these patients, only . % were currently actively receiving treatment. hispanics who screened positive for depression with a history of mdd were less likely to actively be undergoing treatment as compared to non-hispanics ( . % versus . %, p = . ). patients with incomes less than $ , were more likely to actively be receiving treatment as opposed to higher incomes ( . % versus . % p = . ). conclusion: patients presenting to our ed with untreated mdd are more likely to be hispanic and less likely to be low income. the emergency department may offer opportunities to provide antidepressant treatment for patients who screen positive for depression but who are not currently receiving treatment. evaluation of a two-question screening tool (phq- ) for detecting depression in emergency department patients jeffrey p. smith, benjamin bregman, janice blanchard, nasser hashim, mary pat mckay george washington university, washington, dc background: the literature suggests there is a high rate of undiagnosed depression in ed patients and that early intervention can reduce overall morbidity and health care costs. there are several well validated screening tools for depression including the nine-item patient health questionnaire (phq- ). a tool using a two-question subset, the phq- , has been shown to be an easily administered, reasonably sensitive screening tool for depression in primary care settings. objectives: to determine the sensitivity and specificity of the phq- in detecting major depressive disorders (mdd) among adult ed patients presenting to an urban teaching hospital. we hypothesize that the phq- is a rapid, effective screening tool for depression in a general ed population. methods: cross sectional survey of a convenience sample of adult, non-critically ill, english speaking patients with medical and not psychiatric complaints presenting to the ed between am and pm weekdays. patients were screened for mdd with the phq- . we used spss v . to analyze the specificity, sensitivity, positive predictive value (ppv), negative predictive value (npv), and kappa of phq- scores of and (out of possible total score of ) compared to a validated cut-off score of or higher of points on the phq- . the two questions on the phq- are: ''over the last two weeks, how often have you had little interest in doing things? how often have you felt down, depressed or hopeless?'' responses are scored from - based on ''never'',''several days'', ''more than half'', ''nearly every day''. results: subjects of approached agreed to participate ( . % response rate), and ( . %) completed the phq- . the phq- identified ( . %) subjects with mdd. table outlines the percent of subjects who were positive and the sensitivity, specificity, positive, and negative predictive values and kappa for each cut-off on the phq- . conclusion: the phq- is a sensitive and specific screening tool for mdd in the ed setting. moreover, the phq- is closely correlated with the phq- , especially if a score of or greater is used. given the simplicity and ease of using a two-item questionnaire and the high rates of undiagnosed depression in the ed, including this brief, self-administered screening tool to ed patients may allow for early awareness of possible mdd and appropriate evaluation and referral. patients. however, much of this self-harm behavior is not discovered clinically and very little is known about the prevalence and predictors of current ed screening practices. attention to this issue is increasing due to the joint commission's patient safety goal , which focuses on identification of suicide risk in patients. objectives: to describe the prevalence and predictors of screening for self-harm and of presence of current self-harm in eds. methods: data were obtained from the nimh-funded emergency department safety assessment and followup evaluation (ed-safe). eight u.s. eds reviewed charts in real time for - hours a week between / and / . all patients presenting during enrollment shifts were characterized as to whether a selfharm screening had been performed by ed clinicians. a subset of patients with a positive screening was asked about the presence of self-harm ideation, attempts, or both by trained research staff. we used multivariable logistic regression to identify predictors of screening and of current self-harm. data were clustered by site. in each model we examined day and time of presentation, age < years, sex, race, and ethnicity. results: of the , patients presenting during research shift, , ( %) were screened for self-harm. screening rates varied among sites and ranged from % to %, with one outlier at %. of those screened, , ( %) had current self-harm. among those with selfharm approached by study personnel (n = , ), ( %) had thoughts of self-harm (suicidal or non-suicidal), ( %) had thoughts of suicide, ( %) had self-harm behavior, and ( %) had suicide attempt(s) over the preceding week. predictors of being screened were: age < years, male sex, weekend presentation, and night shift presentation (table) . among those screened, predictors of current self-harm were: age < years, white race, and night shift presentation. conclusion: screening for self-harm is uncommon in ed settings, though practices vary dramatically by site. patients presenting at night and on weekends are more likely to be screened, as are those under age and males. current self-harm is more common among those presenting on night shift, those under age , and whites. results: there were out-of-hospital records reviewed, and hospital discharge data were available in non-cardiac arrest patients. of the patients, ( . %) patients survived to hospital discharge and ( . %) died during hospitalization. the mean age of those transported was years (sd ), ( %) were male, ( %) were trauma-related, and ( %) were admitted to the icu. average systolic blood pressure (sbp), pulse (p), respiratory rate (rr), oxygen saturation (o sat), and end-tidal carbon dioxide (etco ) were sbp = (sd ), p = (sd ), rr = (sd ), o sat = % (sd ), and etco = (sd conclusion: of all the initial vital signs recorded in the out-of-hospital setting, etco was the most predictive of mortality. these findings suggest that pre-hospital etco is a useful clinical tool for determining severity of illness and appropriate triage. background: the prehospital use of continuous positive airway pressure (cpap) ventilation is a relatively new management for acute cardiogenic pulmonary edema (acpe) and there is little high quality evidence on the benefits or potential dangers in this setting. objectives: the aim of this study was to determine whether patients in severe respiratory distress treated with cpap in the prehospital setting have a lower mortality than those treated with usual care. methods: randomized, controlled trial comparing usual care versus cpap (whisperflowÒ) in a prehospital setting, for adults experiencing severe respiratory distress, with falling respiratory efforts, due to a presumed acpe. patients were randomised to receive either usual care, including conventional medications (nitrates, furosemide, and oxygen) plus bag-valve-mask ventilation, versus conventional medications plus cpap. the primary outcome was prehospital or in-hospital mortality. secondary outcomes were need for tracheal intubation, length of hospital stay, change in vital signs, and arterial blood gas results. we calculated relative risk with % cis. results: fifty patients were enrolled with mean age ae (sd ae ), male ae %, mortality ae %. the risk of death was significantly reduced in the cpap arm with mortality ae % ( deaths) in the usual care arm compared to ae % ( death) in the cpap arm (rr, ae ; % ci ae to ae ; p = ae ). patients who received cpap were significantly less likely to have respiratory acidosis (mean difference in ph ae ; % ci ae to ae ; p = ae ; n = ) than patients receiving usual care. the length of hospital stay was significantly less in the patients who received cpap (mean difference ae days; % ci ) ae to ae , p = ae ). conclusion: we found that cpap significantly reduced mortality, respiratory acidosis, and length of hospital stay for patients in severe respiratory distress caused by acpe. this study shows the use of cpap for acpe improves patient outcomes in the prehospital setting. (originally submitted as a ''late-breaker.'') trial reg. anzctr actrn ; funding fisher and paykal suppliers of the whisperflowÒ cpap device. background: because emergency service utilization continues to climb, validated methods to safely identify and triage low-acuity patients to either alternate care destinations or a complaint-appropriate level of ems response is of keen interest to ems systems and potentially payers. though the literature generally supports the medical priority dispatch system (mpds) as a tool to predict low-acuity patients by various standards, correlation with initial patient physiologic data and patient age is novel. objectives: to determine whether the six mpds priority determinants for protocol (sick person) can be used to predict initial ems patient acuity assessment or severity of an aggregate physiologic score. our longterm goal is to determine whether mpds priority can be used to predict patient acuity and potentially send only a first responder to do an in-person assessment to confirm this acuity, while reserving als transport resources for higher acuity patients. methods: calls dispatched through the wichita-sedgwick county - - center between july , and october , using mpds protocol (sick person) were linked to the ems patient care record for all patients and older. the six mpds priority determinants were evaluated for correlation with initial ems acuity code, initial vital signs, rapid acute physiology score (raps), or patient age. the ems acuity code scores patients from low to severe acuity, based on initial ems assessment. results: there were calls dispatched using protocol for those years of age and older during the period, representing approximately % of all ems calls. there is a significant difference in the first encounter vital signs among different mpds priority levels. based on the logistic regression model, the mpds priority code alone had a sensitivity of % and specificity of % for identifying low-acuity patients with ems acuity score as the standard. the area under the curve (auc) for roc is . for mpds priority codes alone, while addition of age increases this value to . . if we use the raps score as the standard to the mpds priority code, auc is . . if we include both mpds and age in the model, the auc is . . conclusion: in our system, mpds priority codes on protocol (sick person) alone, or with age or raps score, are not useful either as predictors of patient acuity on ems arrival or to reconfigure system response or patient destination protocols. alternate ambulance destination program c. nee-kofi mould-millman , tim mcmahan , michael colman , leon h. haley , arthur h. yancey emory university, atlanta, ga; grady ems, atlanta, ga background: low-acuity patients calling - - are known to utilize a large proportion of ems and ed resources. the national association of ems physicians and acep jointly support ems alternate destination programs (adps) in which low-acuity patients are allocated alternative resources non-emergently. analysis of one year's adp data from our ems system revealed that only . % of eligible patients were transported to alternate destinations (ambulatory clinics). reasons for this low success rate need investigation. objectives: to survey emts and discover the most frequent reasons given by them for transportation of eligible patients to eds instead of to clinics. methods: this study was conducted within a large, urban, hospital-based ems system. upon conducting an adp for months, a paper-based survey was created and pre-tested. all medics with any adp-eligible patient contact were included. emts were asked about personal, patient, and system related factors contributing to ed transport during the last months of the adp. qualitative data were coded, collated, and descriptively reported. results: sixty-three respondents ( emt-intermediates and emt-paramedics) completed the survey, representing % of eligible emts. thirty-one emts ( %) responded that they did not attempt to recruit eligible patients into the adp in the last program months. of those emts, ( %) attributed their motive to multiple, prior, failed recruitment attempts. the emts who actively recruited adp patients were asked reasons given by patients for clinic transport refusals: ( %) cited that patients reported no prior experience of care at the participating clinics, and ( %) reported patients had a strong preference for care in an ed. regarding system-related factors contributing to non-clinic transport, of the emts ( %) reported that clinic-consenting patients were denied clinic visits, mostly because of non-availability of same-day clinic appointments. conclusion: respondents indicated that poor emt enrollment of eligible patients, lack of available clinic time slots, and patient preference for ed care were among the most frequent reasons contributing to the low success rate of the adp. this information can be used to enhance the success of this, and potentially other adp programs, through modifications to adp operations and improved patient education. the effect of a standardized offline pain treatment protocol in the prehospital setting on pediatric pain treatment brent kaziny , maija holsti , nanette dudley , peter taillac , hsin-yi weng , kathleen adelgais university of utah, school of medicine, salt lake city, ut; university of colorado, school of medicine, aurora, co background: pain is often under treated in children. barriers include need for iv access, fear of delayed transport, and possible complications. protocols to treat pain in the prehospital setting improve rates of pain treatment in adults. the utah ems for children (emsc) program developed offline pediatric protocol guidelines for ems providers, including one protocol that allows intranasal analgesia delivery to children in the prehospital setting. objectives: to compare the proportion of pediatric patients receiving analgesia for orthopedic injury by prehospital providers before and after implementation of an offline pediatric pain treatment protocol. methods: we conducted a retrospective study of patients entered into the utah prehospital on-line active reporting information system (polaris, a database of statewide ems cases) both before and after initiation of the pain protocol. patients were included if they were age - years, with a gcs of - , an isolated extremity injury, and were transported by an ems agency that had adopted the protocol. pain treatment was compared for years before and months after protocol implementation with a wash-out period of months for agency training. the difference in treatment proportions between the two groups was analyzed and % cis were calculated. results: during the two study periods, patients met inclusion criteria. patient demographics are outlined in the table. / ( . %) patients were treated for pain before compared to / ( . %) patients treated after the pain protocol was implemented; a difference of . % ( % ci: . %- . %). patients were more likely to receive pain medication if they had a pain score documented (or: . ; % ci: . - . ) and if they were treated after the implementation of a pain protocol (or: . ; % ci: . - . ). factors not associated with the treatment of pain include age, sex, and mechanism of injury. conclusion: the creation and adoption of statewide emsc pediatric offline protocol guideline for pain management is associated with a significant increase in use of analgesia for pediatric patients in the prehospital setting. background: evidence-based guidelines are needed to determine the appropriate use of air medical transport, as few criteria currently used predict the need for air transport to a trauma center. we previously developed a clinical decision rule (cdr) to predict mortality in injured, helicopter-transported patients. objectives: this study is a prospective validation of the cdr in a new population. methods: a prospective, observational cohort analysis of injured patients ( ‡ y.o.) transported by helicopter from the scene to one of two level i trauma centers. variables analyzed included patient demographics, diagnoses, and clinical outcomes (in-hospital mortality, emergent surgery w/in hrs, blood transfusion w/in hrs, icu admit greater than hrs, combined outcome of all). prehospital variables were prospectively obtained from air medical providers at the time of transport and included past medical history, mechanism of injury, and clinical factors. descriptive statistics compared those with and without the outcomes of interest. the previous cdr (age ‡ , gcs £ , sbp < , flail chest) was prospectively applied to the new population to determine its accuracy and discriminatory ability. results: patients were transported from october -august . the majority of patients were male ( %), white ( %), with an injury occurring in a rural location ( %). most injuries were blunt ( %) with a median iss of . overall mortality was %. the most common reasons for air transport were: mvc with high risk mechanism ( %), gcs £ ( %), loc > minutes ( %), and mvc > mph ( %). of these, only gcs £ was significantly associated with any of the clinical outcomes. when applying the cdr, the model had a sensitivity of % ( . %- %), a specificity of . % ( . %- . %), a npv of % ( . %- %), and a ppv of . % ( . %- . %) for mortality. the area under the curve for this model was . , suggesting excellent discriminatory ability. conclusion: the air transport decision rule in this study performed with high sensitivity and acceptable specificity in this validation cohort. further external validation in other systems and with ground transported patients are needed in order to improve decision making for the use of helicopter transport of injured patients. background: acute non-variceal upper gastrointestinal (gi) bleeding is a common indication for hospital admission. to appropriately risk-stratify such patients, endoscopy is recommended within hours. given the possibility to safely manage patients as outpatients after endoscopy, risk stratification as part of an emergency department (ed) observation unit (ou) protocol is proposed. objectives: our objective was to determine the ability of an ou upper gi bleeding protocol to identify a lowrisk population, and to expeditiously obtain endoscopy and disposition patients. we also identified rates of outcomes including changes in hemoglobin, abnormal endoscopy findings, admission, and revisits. background: acute uncomplicated pyelonephritis (pyelo) requires no imaging but a ct flank pain protocol (ctfpp) may be ordered to determine if patients with pyelo and flank pain also have an obstructing stone. the prevalence of kidney stone and the characteristics predictive of kidney stone in pyelo patients is unknown. objectives: to determine elements on presentation that predict ureteral stone, as well as prevalence of stone and interventions in patients undergoing ct for pyelo. methods: retrospective study of patients at an academic ed who received a ctfpp scan between / and / . ctfpps were identified and randomly selected for review. pyelo was defined as: positive urine dip for infection and > wbc/hpf on formal urinalysis in addition to flank pain/cva tenderness, chills, fever, nausea, or vomiting. patients were excluded for age < y.o., renal disease, pregnancy, urological anomaly, or recent trauma. clinical data ( elements) were gathered blinded to ct findings; ct results were abstracted separately and blinded to clinical elements. ct findings of hydronephrosis and hyrdroureter (hydro) were used as a proxy for hydro that could be determined by ultrasound prior to ct. patients were categorized into three groups: ureteral stone, no significant findings, and intervention or follow-up required. classification and regression tree analysis was used to determine which variables could identify ureteral stone in this population of pyelo patients. results: out of the patients, ( . %) met criteria for pyelo; subjects had a mean age of ± . and % (n = ) were female. ct revealed ( %, % ci = . - . ) symptomatic stones, and ( %, % ci = . - . ) exams with no significant findings. two patients needed intervention/ follow-up ( %, % ci = . - . ), one for perinephric hemorrhage and the other for pancreatitis. hydro was predictive for ureteral stone with an or = . ( % ci = . - , p < . ). eleven ( %) ureteral stone patients were admitted and ( %) of them had procedures. of these patients, % had ct signs of obstruction, ( %) had hydronephrosis, and ( %) had hydroureter. conclusion: hydronephrosis was predictive of ureteral stone and in-house procedures. prospective study is needed to determine whether ct scan is warranted in patients with pyelonephritis but without hydronephrosis or hydroureter. curative objectives: the specific aim of this analysis was to describe characteristics of patients presenting to the emergency department (ed) at their index diagnosis, and to determine whether emergency presentation precludes treatment with curative intent. methods: we performed a retrospective cohort analysis on a prospectively maintained institutional tumor registry to identify patients diagnosed with crc from - . emrs were reviewed to identify which patients presented to the ed with acute symptoms of crc as the initial sign of their illness. the primary outcome variable was treatment plan (curative vs. palliative). secondary outcome variables included demographics, tumor type and location. descriptive statistics were conducted for major variables. chi-squre and fisher's exact tests were used to detect the association between categorical variables. two-sample t-test was used to identify the association between continuous and categorical variables. results: between jan and dec , patients were identified at our institution with crc. ( %) were male and ( %) were female, with mean age . ; sd: . . thirty-three patients ( . %) initially presented to the ed, of whom ( . %) received palliation. of patients who initially presented elsewhere, ( . %) received palliation. acute ed presentation with crc symptoms did not preclude treatment with curative intent (p = . ). patients who presented emergently were more likely to be female ( % vs male %; p = . ) and older ( vs. ; p = . ). there was no statistically significant relationship between age, sex, tumor location, or type and treatment approach. conclusion: patients with crc may present to the ed with acute symptoms, which ultimately leads to the diagnosis. emergent presentation of crc does not preclude patients from receiving therapy with curative intent. cannabinoid (or . , , and white blood cell (wbc) count ‡ , /mm (or . , % ci . - . ). conclusion: age ‡ years is not associated with need for admission from an ed observation unit. older adults can successfully be cared for in these units. initial temperature, respiratory rate, and pulse were not predictive of admission, but extremely elevated blood pressure was predictive. other relevant predictor variables included comorbidities and elevated wbc count. advanced age should not be a disqualifying criterion for disposition to an ed observation unit. older adult fallers in the emergency department luna ragsdale, cathleen colon-emeric duke university, durham, nc background: approximately / of community-dwelling older adults experience a fall each year, and . million are treated in u.s. emergency departments (ed) annually. the ed offers a potential location for identification of high-risk individuals and initiation of fall-prevention services that may decrease both fall rates and resource utilization. objectives: the goal of this study was to: ) validate an approach to identifying older adults presenting with falls to the ed using administrative data; and ) characterize the older adult who falls and presents to the ed and determine the rate of repeat ed visits, both fall-related and all visits, after an index fall-related visit. methods: we identified all older adults presenting to either of the two hospitals serving durham county residents during a six month period. manual chart review was completed for all encounters with icd codes that may be fall-related. charts were reviewed months prior and months post index visit. descriptive statistics were used to describe the cohort. results: a total of older adults were evaluated in the ed during this time period; ( . %) had an icd code for a potentially fall-related injury. of these, record review identified ( %) with a fall from standing height or less. of the fallers, . % of the patients were discharged, % were admitted, and % were admitted under observation. of those who fell, . % had an ed visit within the previous year. approximately / ( . %) of these were fall related. over half ( . %) of the patients who fell returned to the ed within one year of their index visit. a large proportion ( . %) of the return visits was fall-related. follow-up with a primary care provider or specialist was recommended in % of the patients who were discharged. overall mortality rate for fallers over the year following the index visit was %. conclusion: greater than fifty percent of fallers will return to the ed after an index fall, with a large proportion of the visits related to a fall. a large number of these fallers are discharged home with less than fifty percent having recommended follow-up. the ed represents an important location to identify high-risk older adults to prevent subsequent injuries and resource utilization. objectives: we studied whether falls from a standing position resulted in an increased risk for intracranial or cervical injury verses falling from a seated or lying position. methods: this is a prospective observational study of patients over the age of who presented with a chief complaint of fall to a tertiary care teaching facility. patients were eligible for the study if they were over age , were considered to be at baseline mental status, and were not triaged to the trauma bay. at presentation, a questionnaire was filled out by the treating physician regarding mechanism and position of fall, with responses chosen from a closed list of possibilities. radiographic imaging was obtained at the discretion of the treating physician. charts of enrolled patients were subsequently reviewed to determine imaging results, repeat studies done, or recurrent visits. all patients were called in follow-up at days to assess for delayed complications related to the fall. data were entered into a standardized collection sheet by trained abstractors. data were analyzed with fisher's exact test and descriptive statistics. this study was reviewed and approved by the institutional review board. results: two-hundred sixty two patients were enrolled during the study period. one-hundred ninety eight of these had fallen from standing and fell from either sitting or lying positions. the mean age for patients was (sd . ) for those who fell from standing and (sd . ) for those who fell from sitting or lying. there were patients with injuries who fell from standing: three with subdural hematomas, one with a cerebral contusion, one with an osteophyte fracture at c , and one with an occipital condyle fracture with a chip fracture of c . there were patients with injuries who fell from a seated or lying position: one with a traumatic subarachnoid hemorrhage and one with a type ii dens fracture. the overall rate of traumatic intracranial or cervical injury in elders who fell was %. no patients required surgical intervention. there was no difference in rate of injury between elders who fell from standing versus those who fell from sitting or lying (p = ). (table) . conclusion: both instruments identify the majority of patients as high-risk which will not be helpful in allocating scarce resources. neither the isar nor the trst can distinguish geriatric ed patients at high or low risk for or -month adverse outcomes. these prognostic instruments are not more accurate in dementia or lower literacy subsets. future instruments will need to incorporate different domains related to short-term adverse outcomes. background: for older adults, both inpatient and outpatient care involves not only the patient and physician, but often a family member or informal caregiver. they can assist in medical decision making and in performing the patient's activities of daily living. to date, multiple outpatient studies have examined the positive roles family members play during the physician visit. however, there is very limited information on the involvement of the caregiver in the ed and their relationship with the health outcomes of the patient. objectives: to assess whether the presence of a caregiver influences the overall satisfaction, disposition, and outpatient follow-up of elderly patients. we performed a three-step inquiry of patients over years old who arrived to the upenn ed. patients and care partners were initially given a questionnaire to understand basic demographic data. at the end of the ed stay, patients were given a satisfaction survey and followed through days to assess time to disposition, whether the patient was admitted or discharged, outpatient follow-up, and ed revisit rates. chi-square and t-tests were used to examine the strength of differences in the elderly patients' sociodemographics, self-rated health, receiving aid with their instrumental activities of daily living, and number of health problems by accompaniment status. multivariate regression models were constructed to examine whether the presence or absence of caregivers affected satisfaction, disposition, and follow-up. results: overall satisfaction was higher among patients who had caregivers ( . points), among patients who felt they were respected by their physician ( . points), and had lower lengths of stay ( hours). patients with caregivers were also more likely to be discharged home (or . ) and to follow-up with their regular physician (or . ). there was no evidence to suggest caregivers affected the overall rates of revisits back to an ed. conclusion: for older adults, medical care involves not only the patient and physician, but often a family member or an informal care companion. these results demonstrate the positive influence of caregivers on the patients they accompany, and emergency physicians should define ways to engage these caregivers during their ed stay. this will also allow caregivers to participate when needed and can help to facilitate transitions across care settings. background: shared decision making has been shown to improve patient satisfaction and clinical outcomes for chronic disease management. given the presence of individual variations in the effectiveness and side effects of commonly used analgesics in older adults, shared decision making might also improve clinical outcomes in this setting. objectives: we sought to characterize shared decision making regarding the selection of an outpatient analgesic for older ed patients with acute musculoskeletal pain and to examine associations with outcomes. methods: we conducted a prospective observational study with consecutive enrollment of patients age or older discharged from the ed following evaluation for moderate or severe musculoskeletal pain. two essential components of shared decision making, ) information provided to the patient and ) patient participation in the decision, were assessed via patient interview at one week using four-level likert scales. results: of eligible patients, were reached by phone and completed the survey. only % ( / ) of patients reported receiving 'a lot' of information about the analgesic, and only % ( / ) reported participating 'a lot' in the selection of the analgesic. there were trends towards white patients (p = . ) and patients with higher educational attainment (p = . ) reporting more participation in the decision. after adjusting for sex, race, education, and initial pain severity, patients who reported receiving 'a lot' of information were more likely to report optimal satisfaction with the analgesic than those receiving less information ( % vs. %, p < . ). after the same adjustments, patients who reported participating 'a lot' in the decision were also more likely to report optimal satisfaction with the analgesic ( % vs. %, p < . ) and greater reductions in pain scores (mean reduction in pain . vs. . , p < . ) at one week than those who participated less. background: quality of life (qol) measurements have become increasingly important in outcomes-based research and cost-utility analyses. dementia is a prevalent, often unrecognized, geriatric syndrome that may limit the accuracy of patient self-report in a subset of patients. the relationship between caregiver and geriatric patient qol in the emergency department (ed) is not well understood. objectives: to qualify the relationship between caregiver and geriatric patient qol ratings in ed patients with and without cognitive dysfunction. methods: this was a prospective, consecutive patient, cross-sectional study over two months at one urban academic medical center. trained research assistants screened for cognitive dysfunction using the short blessed test and evaluated health impairment using the quality of life-alzheimer's disease (qol-ad) test. when available in the ed, caregivers were asked to independently complete the qol-ad. consenting subjects were non-critically ill, english-speaking, community-dwelling adults over years of age. responses were compared using wilcoxon signed ranks test to assess the relationships between patient and caregiver scores from the qol-ad stratified by normal or abnormal cognitive screening results. significance was defined by p < . . results: patient qol ratings were obtained from patient-caregiver pairs. patients were % female, % african-american, with a mean age of -years, and % had abnormal cognitive screening tests. compared with caregivers, cognitively normal patients had no significant qol assessment differences except for questions of energy level and overall mood. on the other hand, cognitively impaired patients differed significantly on questions of energy level and ability to perform household chores with a trend towards significant differences for living setting (p = . ) and financial situation (p = . ). in each category, the differences reflected a caregiver underestimation of quality compared with the patient's self-rating. conclusion: discrepancies between qol domains and total scores for patients with cognitive dysfunction and their caregivers highlights the importance of identifying cognitive dysfunction in ed-based outcomes research and cost-utility analyses. further research is needed to quantify the clinical importance of the patient-and caregiver-assessed quality of life. background: age is often a predictor for increased morbidity and mortality. however, it is unclear whether old age is a predictor of adverse outcome in syncope. objectives: to determine whether old age is an independent predictor of adverse outcome in patients presenting to the emergency department following a syncopal episode. methods: a prospective observational study was conducted from june to july enrolling consecutive adult ed patients (> years) presenting with syncope. syncope was defined as an episode of transient loss of consciousness. adverse outcome or critical intervention were defined as gastrointestinal bleeding or other hemorrhage, myocardial infarction/percutaneous coronary intervention, dysrhythmia, alteration in antidysrhythmics, pacemaker/defibrillator placement, sepsis, stroke, death, pulmonary embolus, or carotid stenosis. outcomes were identified by chart review and -day follow-up phone calls. results: of patients who met inclusion criteria, an adverse event occurred in % of patients. overall, % of patients with risk factors had adverse outcomes compared to . % of patients with no risk factors. in particular, / ( %; % ci - %) of patients < with risk factors had adverse outcomes, while / ( %; % ci - %) of the elderly with risk factors had adverse outcomes. in contrast, among young people / ( %; % ci . - . %) of patients without risk factors had adverse outcomes while / ( . %; % ci . - %) of patients ‡ without risk factors had adverse outcomes. conclusion: although the elderly are at greater risk for adverse outcomes in syncope, age ‡ or older alone does not appear to be a predictor of adverse outcome following a syncopal event. based on these data, it should be safe to discharge home from the ed patients with syncope, but without risk factors, regardless of age. (originally submitted as a ''late-breaker.'') antibiotics background: adherence to national guidelines for hiv and syphilis screening in eds is not routine. in our ed, hiv and syphilis screening rates among patients tested for gonorrhea and chlamydia (gc/ct) have been reported to be % and %, respectively. objectives: to determine the effect of a sexually transmitted infection (sti) laboratory order set on hiv and syphilis screening among ed patients tested for gc/ct. we hypothesized that a sti order set would increase screening rates by at least %. methods: a -month, quasi-experimental study in an urban ed comparing hiv and syphilis screening rates of gc/ct-tested patients before (control phase) and after the implementation of a sti laboratory order set (intervention phase). the order set linked blood-based rapid hiv and syphilis screening with gc/ct testing. consecutive patients completing gc/ct testing were included. the primary outcome was the absolute difference in hiv and syphilis screening rates among gc/ ct-tested patients between phases. we estimated that subjects per phase were needed to provide % power (p-value of £ . ) to detect an absolute difference in screening rates of %, assuming a baseline hiv screening rate of %. results: the ed census was , . characteristics of patients tested for gc/ct were similar between phases: the mean age was years (sd = ) and most were female ( %), black ( %), hispanic ( %), and unmarried ( % services have recommended the use of immunization programs against influenza disease within hospitals since the s. the emergency department (ed) being the ''safety net'' for most non-insured people is an ideal setting to intervene and provide primary prevention from influenza. objectives: the purpose of this study is to assess whether a pharmacist-based influenza immunization program is feasible in the ed, and successful in increasing the percentage of adult patients receiving the influenza vaccine. methods: implementation of pharmacist-based immunization program was developed in coordination with ed physicians and nursing staff in . the nursing staff, using an embedded electronic questionnaire within their triage activity, screened patients for eligibility for the influenza vaccine. the pharmacist using an electronic alert system within the electronic medical record identified patients who we deemed eligible and if agreed the pharmacist vaccinated the patient. patients who refused to be vaccinated were surveyed to ascertain their perception concerning immunization offered by a pharmacist in the ed. feasibility and safety data for vaccinating patient in the ed were recorded. results: patients were approached and enrolled into the study. of the , % agreed to receive the influenza vaccine from a pharmacist in the ed. the median screening time was minutes and median vaccination time was minutes for a total of minutes from screening time to vaccination time. % were willing to receive the influenza vaccine from a pharmacist, and % were willing to receive the vaccine in the ed. the main reason given for refusing to receive the influenza vaccine was ''patient does not feel at risk of getting the disease''; only . % stated they were vaccinated recently. conclusion: a pharmacist-based influenza immunization program is feasible in the ed, and has the potential to successfully increase the percentage of adult patients receiving the vaccine. . ± . , p < . ). ed visits by hiv-infected patients also had longer lengths of ed stay ( ± . minutes vs. . ± . minutes, p < . ) and were more likely to be admitted ( % vs. %, p < . ), than their non-hiv infected counterparts. conclusion: although ed visits by hiv-infected individuals in the u.s. are relatively infrequent, they occur at rates higher than the general population, and consume significantly more ed resources than the general population. the background: the influence of wound age on the risk of infection in simple lacerations repaired in the emergency department (ed) has not been well studied. it has traditionally been taught that there is a ''golden period'' beyond which lacerations are at higher risk of infection and therefore should not be closed primarily. the proposed cutoff for this golden period has been highly variable ( - hours in surgical textbooks). objectives: to answer the following research question: are wounds closed via primary repair after the golden period at increased risk for infection? methods: we searched medline, embase, and other databases as well as bibliographies of relevant articles. we included studies that enrolled ed patients with lacerations repaired by primary closure. exclusion: . intentional delayed primary repair or secondary closure, . wounds requiring intra-operative repair, skin graft, drains, or extensive debridement, and . grossly contaminated or infected at presentation. we compared the outcome of wound infection in two groups of early versus delayed presentations (based on the cut-offs selected by the original articles). we used ''grading of recommendations assessment, development and evaluation'' (grade) criteria to assess the quality of the included trials. frequencies are presented as percentages with % confidence intervals. relative risk (rr) of infection is reported when clinically significant. results: studies were identified. four trials enrolling patients in aggregate met our inclusion/exclusion criteria. two studies used a -hour cut-off and the other two used a -hour cut-off for defining delayed wounds. the overall quality of evidence was low. the infection rate in the wounds that presented with delay ranged from . % to %. one study with the smallest sample size (morgan et al), which only enrolled lacerations to the hand and forearm, showed higher rates of infection in patients with delayed wounds (table). the infection rates in delayed wound groups in the remaining three studies were not significantly different from the early wounds. conclusion: the evidence does not support the existence of a golden period, nor does it support the role of wound age on infection rate in simple lacerations. background: although clinical studies in children have shown that temperature elevation is an independent and significant predictor of bacteremia in children, the relationship in adults is largely unknown or equivocal. objectives: review the incidence of positive blood cultures on critically ill adult septic patients presenting to an emergency department (ed) and determine the association of initial temperature with bacteremia. methods: july to july retrospective chart review on all patients admitted from the ed to an urban community hospital with sepsis and subsequently expiring within days of admission. fever was defined as a temperature ‡ °c. sirs criteria were defined as: ) temperature ‡ °c or £ °c, ) heart rate ‡ beats/ minute, ) respiratory rate ‡ or mechanical ventilation, ) wbc ‡ , /mm or < , or bands ‡ %. objectives: we examined the utility of limited genetic sequencing of bacterial isolates using multilocus sequence typing (mlst) to discriminate between known pathogenic blood culture isolates of s. epidermidis and isolates recovered from skin. methods: ten blood culture isolates from patients meeting the centers for disease control and prevention (cdc) criteria for clinically significant s. epidermidis bacteremia and ten isolates from the skin of healthy volunteers were studied. mlst was performed by sequencing bp regions of seven genes (arc, aroe, gtr, muts, pyr, tpia, and yqil) . genetic variability at these sites was compared to an international database (www.sepidermidis.mlst.net) and each strain was then categorized into a genotype on the basis of known genetic variation. the ability of the gene sequences to correctly classify strains was quantified using the support vector machine function in the statistical package r. , bootstrap resamples were performed to generate confidence bounds around the accuracy estimates. results: between-strain variability was considerable, with yqil being most variable ( alleles) and tpia being least ( allele). the muts gene, responsible for dna repair in s. epidermidis, showed almost complete separation between pathogenic and commensal strains. when the seven genes were used in a joint model, they correctly predicted bacterial strain type with % accuracy (iqr , %). conclusion: multilocus sequence typing shows excellent early promise as a means of distinguishing contaminant versus truly pathogenic isolates of s. epidermidis from clinical samples. near-term future goals will involve developing more rapid means of sequencing and enrolling a larger cohort to verify assay performance. conference are presented by influenza scenario in table and background: antiviral medications are recommended for patients with influenza who are hospitalized or at high risk for complications. however, timely diagnosis of influenza in the ed remains challenging. influenza rapid antigen tests have short turn-around times, making them potentially useful in the ed setting, but their sensitivities may be too low to assist with treatment decisions. objectives: to evaluate the test characteristics of the binaxnow influenza a&b rapid antigen test (rat) in ed patients. methods: we prospectively enrolled a systematic sample of patients of all ages presenting to two eds with acute respiratory symptoms or fever during three consecutive influenza seasons ( ) ( ) ( ) ( ) . research personnel collected nasal and throat swabs, which were combined and tested for influenza with rt-pcr using cdc-provided primers and probes. ed clinicians independently decided whether to obtain a rat during clinical care. rats were performed in the clinical laboratory using the binaxnow influenza a&b test on nasal swabs collected by ed staff. the study cohort included subjects who underwent both a research pcr and clinical rat. rat test characteristics were evaluated using pcr as the criterion standard with stratified sub-analyses for age group and influenza subtype (pandemic h n (ph n ), non-pandemic influenza a, influenza b). results: subjects were enrolled; subjects were pcr positive for influenza ( ph n , non-pandemic influenza a, and influenza b). for all age groups, rat sensitivities were low and specificities were high ( hiv infection with cd < ; and among nursing home residents, inability to independently perform activities of daily living. sources for bacterial cultures included blood, sputum (adults only), bronchoalveolar lavage (bal), tracheal aspirate, and pleural fluid. only sputum specimens with a bartlett score ‡ + were considered adequate for culturing. results: among children enrolled, ( %) had s. aureus cultured from ‡ specimen, including with methicillin-resistant s. aureus (mrsa) and with methicillin-susceptible s. aureus (mssa). specimens positive for s. aureus included pleural fluid, blood, tracheal aspirates, and bal. two children with s. aureus had evidence of co-infection: influenza a, and streptococcus pneumoniae. among adults enrolled, ( %) grew s. aureus from ‡ specimen, including with mrsa and with mssa. specimens positive for s. aureus included blood, sputum, and bal. five adults with s. aureus had evidence of co-infections: coronavirus, respiratory syncytial virus, s. pneumoniae, and pseudomonas aeruginosa. presenting clinical characteristics and outcomes of subjects with staphylococcal cap are summarized in tables - . conclusion: these preliminary findings suggest s. aureus is an uncommon cause of cap. although the small number of staphylococcal cases limits conclusions that can be drawn, in our analysis staphylococcal cap appears to be associated with co-infections, pleural effusions, and severe disease. future work will focus on continued enrollment and developing clinical prediction models to aid in diagnosing staphylococcal cap in the ed. background: emergency care has been a neglected public health challenge in sub-saharan africa. the goal of global emergency care collaborative (gecc) is to develop a sustainable model for emergency care delivery in low-resource settings. gecc is developing a training program for emergency care practitioners (ecps). objectives: to analyze the first patient visits at karoli lwanga ''nyakibale'' hospital ed in rural uganda to determine the knowledge and skills needed in training ecps. methods: a descriptive cross-sectional analysis of the first consecutive patient visits in the ed's patient care log was reviewed by an unblinded abstractor. data on demographics, procedures, laboratory testing, bedside ultrasounds (us) performed, radiographs (xrs) ordered, and diagnoses were collated. all authors discussed uncertainties and formed a consensus. descriptive statistics were performed. results: of the first patient visits, procedures were performed in ( . %) patients, including ( . %) who had ivs placed, ( . %) who received wound care, and ( . %) who received sutures. complex procedures, such as procedural sedations, lumbar punctures, orthopedic reductions, nerve blocks, and tube thoracostomies, occurred in ( . %) patients. laboratory testing, xrs, and uss were performed in ,( . %), ( . %), and ( %) patients, respectively. infectious diseases were diagnosed in ( . %) patients; ( . %) with malaria and ( . %) with pneumonia. traumatic injuries were present in ( %) patients; ( . %) needing wound care and ( . %) with fractures. gastrointestinal and neurological diagnoses affected ( . %) and ( . %) patients, respectively. conclusion: ecps providing emergency care in sub-saharan africa will be required to treat a wide variety of patient complaints and effectively use laboratory testing, xrs, and uss. this demands training in a broad range of clinical, diagnostic, and procedural skills, specifically in infectious disease and trauma, the two most prevalent conditions seen in this rural sub-saharan africa ed. assessment of point-of-care ultrasound in tanzania background: current chinese ems is faced with many challenges due to a lack of systematic planning, national standards in training, and standardized protocols for prehospital patient evaluation and management. objectives: to estimate the frequency with which prehospital care providers perform critical actions for selected chief complaints in a county-level ems system in hunan province, china. methods: in collaboration with xiangya hospital (xyh), central south university in hunan, china, we collected data pertaining to prehospital evaluation of patients on ems dispatches from a '' - - '' call center over a -month period. this call center services an area of just under km with a total population of . million. each ems team consists of a driver, a nurse, and a physician. this was a cross-sectional study where a single trained observer accompanied ems teams on transports of patients with a chief complaint of chest pain, dyspnea, trauma, or altered mental status. in this convenience sample, data were collected daily between am and pm. critical actions were pre-determined by a panel of emergency medicine faculty from xyh and the university of maryland school of medicine. simple statistical analysis was performed to determine the frequency of critical actions performed by ems providers. results: during the study period, patients were transported, of whom met the inclusion criteria. ( . %) evaluations were observed directly for critical actions. the table shows the frequency of critical actions performed by chief complaint. none of the patients with chest pain received an ecg even though the equipment was available. rapid glucose was checked in only . % of patients presenting with altered mental status. a lung exam was performed in . % of patients with dyspnea, and the respiratory rate was measured in . %. among patients transported for trauma, blood pressure, and heart rate were only measured in % and . %, respectively. conclusion: in this observation study of prehospital patient assessments in a county-level ems system, critical actions were performed infrequently for the chief complaints of interest. performance frequencies for critical actions ranged from to . %, depending on the chief complaint. standardized prehospital patient care protocols should be established in china and further training is needed to optimize patient assessment. trends little is known about the comparative effectiveness of noninvasive ventilation (niv) versus invasive mechanical ventilation (imv) in chronic obstructive pulmonary disease (copd) patients with acute respiratory failure. objectives: to characterize the use of niv and imv in copd patients presenting to the emergency department (ed) with acute respiratory failure and to compare the effectiveness of niv vs. imv. methods: we analyzed the - nationwide emergency department sample (neds), the largest, all-payer, us ed and inpatient database. ed visits for copd with acute respiratory failure were identified with a combination of copd exacerbation and respiratory failure icd- -cm codes. patients were divided into three treatment groups: niv use, imv use, and combined use of niv and imv. the outcome measures were inpatient mortality, hospital length of stay (los), hospital charges, and complications. propensity score analysis was performed using patient and hospital characteristics and selected interaction terms. results: there were an estimated , visits annually for copd exacerbation and respiratory failure from approximately , eds. ninety-six percent were admitted to the hospital. of these, niv use increased slightly from % in to % in (p = . ), while imv use decreased from % in to % in (p < . ); the combined use remained stable ( %). inpatient mortality decreased from % in to % in (p < . ). niv use varied widely between hospitals, ranging from % to % with median of %. in a propensity score analysis, niv use (compared to imv) significantly reduced inpatient mortality (risk ratio . ; % confidence interval [ci] . - . ), shortened hospital los (difference ) days; %ci ) to ) ), and reduced hospital charges ; ) . niv use was associated with a lower rate of iatrogenic pneumothorax compared with imv use ( . % vs. . %, p < . ). an instrumental analysis confirmed the benefits of niv use, with a % reduction in inpatient mortality in the niv-preferring hospitals. conclusion: niv use is increasing in us hospitals for copd with acute respiratory failure; however, its adoption remains low and varies widely between hospitals. niv appears to be more effective and safer than imv in the real-world setting. background: dyspnea is a common ed complaint with a broad differential diagnosis and disease-specific treatment. bronchospasm alters capnographic waveforms, but the effect of other causes of dyspnea on waveform morphology is unclear. objectives: we evaluated the utility of capnographic waveforms in distinguishing dyspnea caused by reactive airway disease (rad) from non-rad in adult ed patients. methods: this was a prospective, observational, pilot study of a convenience sample of adult patients presenting to the ed with dyspnea. waveforms, demographics, past medical history, and visit data were collected. waveforms were independently interpreted by two blinded reviewers. when the interpreters disagreed, the waveform was re-reviewed by both reviewers and an agreement was reached. treating physician diagnosis was considered the criterion standard. descriptive statistics were used to characterize the study population. diagnostic test characteristics and inter-rater reliability are given. results: fifty subjects were enrolled. median age was years (range - ), % were female, % were caucasian. / ( %) had a history of asthma or chronic obstructive pulmonary disease. rad was diagnosed by the treating physician in / ( %) and / ( %) had received treatment for dyspnea prior to waveform acquisition. the interpreters agreed on waveform analysis in / ( %) cases (kappa = . ). test characteristics for presence of acute rad, including %ci, were: overall accuracy % ( . %- . %), sensitivity % ( . %- . %), specificity % ( . %- . %), positive predictive value % ( . %- . %), negative predictive value % ( . %- . %), positive likelihood ratio . ( . - . ) , negative likelihood ratio . ( . - . ). conclusion: inter-rater agreement is high for capnographic waveform interpretation, and shows promise for helping to distinguish between dyspnea caused by rad and dyspnea from other causes in the ed. treatments received prior to waveform acquisition may affect agreement between waveform interpretation and physician diagnosis, affecting the observed test characteristics. asthma background: asthma and chronic obstructive pulmonary disease (copd) patients who present to the emergency department (ed) usually lack adequate ambulatory disease control. while evidence-based care in the ed is now well defined, there is limited inform-ation regarding the pharmacologic or non-pharmacologic needs of these patients at discharge. objectives: this study evaluated patients' needs with regard to the ambulatory management of their respiratory conditions after ed treatment and discharge. methods: over months, adult patients with acute asthma or copd, presenting to a tertiary care alberta hospital ed and discharged after being treated for exacerbations, were enrolled. using results from standardized in-person questionnaires, charts were reviewed by respiratory researchers to identify care gaps. results: overall, asthmatic and copd patients were enrolled. more patients with asthma required education on spacer devices ( % vs %). few asthma ( %) and no copd patients had written action plans; asthma patients were more likely to need adherence counseling ( % vs %) for preventer medications. more patients with asthma required influenza vaccination ( % vs %; p = . ); pneumococcal immunization was low ( %) in copd patients. only % of asthmatics reported ever being referred to an asthma education program and % of the copd patients reported ever being referred to pulmonary rehabilitation. at ed presentation, % of the asthmatics required the addition of inhaled corticosteroids (ics) and % required the addition of ics/long acting beta-agonist (ics/laba) combination agents. on the other hand, % of copd patients required the addition of long-acting anticholinergics while most ( %) were receiving preventer medications. finally, % of copd and % of asthma patients who smoked required smoking cessation counseling. conclusion: overall, we identified various care gaps for patients presenting to the ed with asthma and copd. there is an urgent need for high-quality research on interventions to reduce these gaps. methods: this is an interim, sub-analysis of an interventional, double-blinded study performed in an academic urban-based adult ed. subjects with acute exacerbation of asthma with fev < % predicted within minutes following initiation of ''standard care'' (including a minimum of mg nebulized albuterol, . mg nebulized ipratropium, and mg corticosteroid) who consented to be in a trial were included. all treatment was administered by emergency physicians unaware of the study objectives. patients were randomly assigned to treatment with placebo or an intravenous beta agonist. all subjects had fev and ds obtained at baseline, , , and hours after treatment. fev was measured using a bedside nspire spirometer, and ds was calculated using a modified borg dyspnea score. results: thirty-eight patients were included for analysis. spearman's rho test (rho) was used to measure correlations between fev and ds at , , and hours post study entry and subsequent hospitalization. rho is negative for fev (higher fev correlates to lower rate of hospitalization) and positive for ds (higher ds correlates to higher rate of hospitalization). at each time point, ds were more highly correlated to hospitalization than were fev (see table) . conclusion: dyspnea score at , , and hours were significantly correlated with hospital admission, whereas fev was not. in this set of subjects with moderate to severe asthma exacerbations, a standardized subjective tool was superior to fev for predicting subsequent hospitalization. methods: this is an interim, subgroup analysis of a prospective, interventional, double-blind study performed in an academic urban ed. subjects who were consented for this trial presented with acute asthma exacerbations with fev £ % predicted within minutes following initiation of ''standard care'' (includes a minimum of . mg nebulized albuterol, . mg nebulized ipratropium, and mg of a corticosteroid). ed physicians who were unaware of the study objectives administered all treatments. subjects were randomized in a : ratio to either placebo or investigational intravenous beta agonist arms. blood was obtained at and . hours after the start of the hour long infusion. blood was centrifuged and serum stored at ) °c, and then shipped on dry ice for albuterol and lactate measurements at a central lab. the treatment lactate and d lactate were correlated with hr serum albuterol concentrations and hospital admission using partial pearson correlations to adjust for ds. results: subjects were enrolled to date, with complete data. the mean baseline serum lactate level was . mg/dl (sd ± . ). this increased to . mg/ dl (sd ± . ) at . hrs. the mean hr ds was . (sd ± . ). the correlations between treatment lactate, d lactate, hr serum albuterol concentrations (r, s and total) and admission to hospital are shown (see table) . both treatment and d lactate were highly conrrelated with total serum albuterol, r albuterol, and s albuterol. there was no correlation between treatment lactate or d lactate and hospital admission. conclusion: lactate and d lactate concentrations correlate with albuterol concentrations in patients presenting had asthma. fifty one percent were < years old and % were female. we found a decline of % ( % ci: %- %, p < . ; r = . , p < . ) in the overall yearly asthma visits to total ed visits from to . when we analyzed sex and age groups separately, we found no statistically significant changes for females or for males < years old (r £ . , p ‡ . ). for females and males > years old, yearly asthma visits to total ed visits from to decreased % ( % ci: %- %, p < . ; r = . , p < . ) and % ( % ci: %- %, p < . ; r = . , p < . ), respectively. conclusion: we found an overall decrease in yearly asthma visits to total ed visits from to . we speculate that this decrease is due to greater corticosteroid use despite the increasing prevalence of asthma. it is unclear why this decrease was seen in adults and not in children and why it was greater for adult females than males. objectives: our objectives were to describe the use of a unique data collection system that leveraged emr technology and to compare its data entry error rate to traditional paper data collection. methods: this is a retrospective review of data collection methods during the first months of a multicenter study of ed, anti-coagulated, head injury patients. on-shift ed physicians at five centers enrolled eligible patients and prospectively completed a data form. enrolling ed physicians had the option of completing a one-page paper data form or an electronic ''dotphrase'' (dp) data form. our hospital system uses an epicÒbased emr. a feature of this system is the ability to use dps to assist in medical information entry. a dp is a preset template that may be inserted into the emr when the physician types a period followed by a code phrase (in this case ''.ichstudy''). once the study dp was inserted at the bottom of the electronic ed note, it prompted enrolling physicians to answer study questions. investigators then extracted data directly from the emr. our primary outcomes of interest were the prevalence of dp data form use and rates of data entry errors. results: from / through / , patients were enrolled. dp data forms were used in ( . %; % ci . , . %) cases and paper data forms in ( . %; % ci . , . %). the prevalence of dp data form use at the respective study centers was %, %, %, %, and %. sixty-six ( . %; % ci . , . %) of physicians enrolling patients used dp data entry at least once. using multivariate analysis, we found no significant association between physician age, sex, or tenure and dp use. data entry errors were more likely on paper forms ( / , . %; % ci . , . %) than dp data forms ( / , . %; % ci . , . %), difference in error rates . % ( % ci . , . %, p < . ). conclusion: dp data collection is a feasible means of study data collection. dp data forms maintain all study data within the secure emr environment obviating the need to maintain and collect paper data forms. this innovation was embraced by many of our emergency physicians. we found lower data entry error rates with dp data forms compared to paper forms. background: inadequate randomization, allocation concealment, and blinding can inflate effect sizes in both human and animal studies. these methodological limitations might in part explain some of the discrepancy between promising results in animal models and non-significant results in human trials. whereas blinding is not always possible, in clinical or animal studies, true randomization with allocation concealment is always possible, and may be as important in minimizing bias. objectives: to determine the frequency with which published emergency medicine (em) animal research studies report randomization, specific randomization methods, allocation concealment, and blinding of interventions and measurements, and to estimate whether these have changed over time. methods: all em animal research publications from / through / in ann emerg med and acad emerg med were reviewed by two trained investigators for a statement regarding randomization, and specific descriptions of randomization methods, allocation concealment, blinding of intervention, and blinding of measurements, when possible. raw initial agreement was calculated and differences were settled by consensus. the first (period = - ) and second (period = - ) -year periods were compared with % confidence intervals. results: of em animal research studies, were appropriate for review because they involved intervention in at least two groups. blinding of interventions and measurements were not considered possible in % and %, respectively. significant differences between period and were absent, although there was a trend towards less blinding of interventions and more blinding of measurements. raw agreement was %. conclusion: although randomization is mentioned in the majority of studies, allocation concealment and blinding remain underutilized in em animal research. we did not compare outcomes between blinded and non-blinded, randomized and non-randomized studies, because of small sample size. this review fails to demonstrate significant improvement over time in these methodological limitations in em animal research publications. journals might consider requiring authors to explicitly describe their randomization, allocation, and blinding methods. background: cluster randomized trials (crts) are increasingly utilized to evaluate quality improvement interventions aimed at health care providers. in trials testing ed interventions, migration of eps between hospitals is an important concern, as contamination may affect both internal and external validity. objectives: we hypothesized geographically isolating emergency departments would prevent migratory contamination in a crt designed to increase ed delivery of tpa in stroke (the instinct trial). methods: instinct was a prospective, cluster-randomized, controlled trial. twenty-four michigan community hospitals were randomly selected in matched pairs for study. following selection of a single hospital, all hospitals within miles were excluded from the sample pool. individual emergency physicians staffing each site were identified at baseline ( ) and months later. contamination was defined at the cluster level, with substantial contamination defined a priori as > % of eps affected. non-adherence, total crossover (contamination + non-adherence), migration distance and characteristics were determined. results: emergency physicians were identified at all sites. overall, ( . %) changed study sites. one moved between control sites, leaving ( . %) total crossovers. of these, ( . %) moved from intervention to control (contamination) and ( . %) moved from control to intervention (non-adherence). contamination was observed in of sites, with % and % contamination of the total site ep workforce at follow-up, respectively. two of crossovers occurred between hospitals within the same health system. average migration distance was miles for all eps in the study and miles for eps moving from intervention to control sites. conclusion: the mobile nature of emergency physicians should be considered in the design of quality improvement crts. use of a -mile exclusion zone in hospital selection for this crt was associated with very low levels of substantial cluster contamination ( of ) and total crossover. assignment of hospitals from a single health system to a single study group and/or an exclusion zone of miles would have further reduced crossovers. increased reporting of contamination in cluster randomized controlled trials is encouraged to clarify thresholds and facilitate crt design. objectives: an extension of the lr, the average absolute likelihood ratio (aalr), was developed to assess the average change in the odds of disease that can be expected from a test, or series of tests, and an example of its use to diagnose wide qrs complex tachycardia (wct) is provided. methods: results from two retrospective multicenter case series were used to assess the utility of qrs duration and axis to assess for ventricular tachycardia (vt) in patients with undifferentiated regular sustained wct. serial patients with heart rate (hr) > beats per minute and qrs duration > milliseconds (msec) were included. the final tachydysrhythmia diagnosis was determined by a number of methods independent of the ecg. the aalr is defined as: aalr = /n total [r (n i *lr i ) (for lr > ) + r (n k /lr k ) (for lr < )], where lr i and lr k are the interval lrs, and n i and n k are the number of patients with test results within the corresponding intervals. roc curves were constructed, and interval lrs and aalrs were calculated for the qrs duration and axis tests individually, and when applied together. confidence intervals were bootstrapped with , replications using the r boot package. results: patients were included: with supraventricular tachycardia (svt) and with vt. optimal qrs intervals (msec) for distinguishing vt from svt were: qrs £ , < qrs < , and qrs ‡ . qrs axis results were dichotomized to upward right axis ( - degrees) or not () to degrees). results are listed in the table. conclusion: application of the qrs interval and axis tests together for patients with wide qrs complex tachycardia changes the odds of ventricular tachycardia, on average, by a factor of . ( % ci . to . ), and this is mildly improved over the qrs duration test alone. both a strength and weakness of the aalr is its dependence on the pretest probability of disease. the aalr may be helpful for clinicians and researchers to evaluate and compare diagnostic testing approaches, particularly when strategies with serial non-independent tests are considered. consultation for adults with metastatic solid tumors at an urban, academic ed located within a tertiary care referral center. field notes were grouped into barrier categories and then quantified when possible. patient demographics for those who did and did not enroll were extracted from the medical record and quantified. patients who did not meet inclusion criteria for the study (e.g., cognitive impairment) were excluded from the analysis. results: attempts were made to enroll eligible patients in the study, and were successfully enrolled ( % enrollment rate). barriers to enrollment were deduced from the field notes and placed into the following categories from most to least common: patient refusal ( ); diagnostic uncertainty regarding cancer stage ( ); severity of symptoms preclude participation ( ); patient unaware of illness or stage ( ); and family refusal ( ). conclusion: patients, families, and diagnostic uncertainty are barriers to enrolling ed patients with advanced illness in clinical trials. it is unclear whether these barriers are generalizable to other study sites and disease processes other than cancer. objectives: the purpose of this study was to evaluate the use of a high-fidelity mannequin bedside simulation scenario followed by a debriefing session as a tool to improve medical student knowledge of palliative care techniques. methods: third year medical students participating in a -week simulation curriculum during a surgery/ emergency medicine/anesthesia clerkship were eligible for the study. all students were administered a pretest to evaluate their baseline knowledge of palliative care and randomized to a control or intervention group. during week or , students in the intervention group participated in and observed two end-of-life scenarios. following the scenarios, a faculty debriefer trained in palliative care addressed critical actions in each scenario. during week , all students received a posttest to evaluate for improvement in knowledge. the pre-test and post-test consisted of questions addressing prognostication, symptom control, and the medicare hospice benefit. students were de-identified and pre-and post-tests were graded by a blinded scorer. results: from jan-dec , students were included in the study and were excluded due to incomplete data. the mean score on the pre-test for the intervention group was . , and for the control group was . (p = . the results indicate that educators identify the most important scenarios as protocol-based simulations. respondents also suggested that scenarios of very common emergency department presentations bear a great deal of importance. emergency medicine educators assign priority to simulations involving professionalism and communication. finally, many respondents noted that they use simulation to teach the presentation and management of rare or less frequent, but important disease processes. the identification of these scenarios would suggest that educators find simulation useful for filling in ''gaps'' in resident education. background: prescription drug misuse is a growing problem among adolescent and young adult populations. objectives: to determine factors associated with past year prescription drug misuse defined as using prescription sedatives, stimulants, or opioids to get high, taking them when they were prescribed to someone else or taking more than was prescribed among patients seeking care in an academic ed. methods: adolescents and young adults ( - ) presenting for ed care at a large, academic teaching hospital were approached to complete a computerized screening questionnaire regarding demographics, prescription drug misuse, illicit drug use, alcohol use, and violence in the past months. logistic regression was used to predict past year prescription drug misuse. results: over the study time period, there were participants ( % response rate) of whom ( . %) endorsed past year prescription drug misuse. specifically, rates of past year misuse for opioids was . %, sedatives was . %, and stimulants was . %. significant overlap exists among classes with over % misusing more than one class of medications. in the multivariate analysis significant predictors of past year prescription drug misuse included female gender (or conclusion: approximately one in seven adolescents or young adults seeking ed care have misused prescription drugs in the past year. while opioids are the most common drug misused, significant overlap exists among this population. given the correlation of prescription drug misuse with the use and misuse of other substances (i.e. alcohol, cough medicine, marijuana) more research is needed to further understand these relationships and inform interventions. additionally, future research should focus on understanding the differences in demographics and risk factors associated with misuse of each separate class of prescription drugs. prospective objectives: this study aims to examine the association of depression with high ed utilization in patients with non-specific abdominal pain. methods: this single-center, prospective, cross-sectional study was conducted in an urban academic ed located in washington, dc as part of a larger study to evaluate the interaction between depression and frequency of ed visits and chronic pain. as part of this study, we screened patients using the phq- , a nineitem questionnaire that is a validated, reliable predictor of major depressive disorder. we analyzed the subset of respondents with a non-specific abdominal pain diagnosis (icd- code of .xx). our principal outcome of interest was the rate of a positive depression screen in patients with non-specific abdominal pain. we analyzed the prevalence of a positive depression screen among this group and also conducted a chi-square analysis to compare high ed use among abdominal pain patients with a positive depression screen versus those without a positive depression screen. we defined high ed utilization as > visits in a -day period prior to the enrollment visit. background: numerous studies have found high rates of co-morbid mental illness and chronic pain in emergent care settings. one psychiatric diagnosis frequently associated with chronic pain is major depressive disorder (mdd). objectives: we conducted a study to characterize the relationship between mdd and chronic pain in the emergency department (ed) population. we hypothesized that patients who present to the ed with selfreported chronic pain will have higher rates of mdd. methods: this was a single-center, prospective, crosssectional study. we used a convenience sample of noncritically ill, english speaking adult patients presenting with non-psychiatric complaints to an urban academic ed over months in . we oversampled patients presenting with pain-related complaints (musculoskeletal pain or headache). subjects were surveyed about their demographic and other health and health care characteristics and were screened with the phq , a nine-item questionnaire that is a validated, reliable predictor of mdd. we conducted bivariate (chi-square) and multivariate analysis controlling for demographic characteristics (race, income, sex, age) using stata v. . . our principal dependent variable of interest was a positive depression screen (phq score ‡ ). our principal independent variable of interest was the presence of self-reported chronic pain (greater than months). results: of patients enrolled, did not meet all inclusion criteria. had two or more assessments for comparison. their average age was (range - ), % were male, and % were in police custody. % used methadone alone; % heroin alone; % oxycodone alone; and the rest used multiple opioids. the average dose of im methadone was . mg (range - mg); all but patients received mg. the mean cows score before receiving im methadone was . (range - ), compared to . (range - ) minutes after methadone (p < . ; mean difference = ) . ; % ci = ) . to ) . ). the mean wss before and after methadone was ) . (range ) to ) ) and ) . (range ) to ), respectively (p < . ; % ci = ) . to ) . ). the mean physician-assessed wss was significantly lower than the patient's own assessment by . (p < . ). adverse events included an asthmatic patient with bronchospasm whose oxygen saturation decreased from % to % after receiving methadone, a patient whose oxygen saturation decreased from % to %, and two patients whose amss decreased from ) to ) (indicating moderate sedation). background: as the us population ages, the coexistence of copd and acute coronary syndrome (acs) is expected to be more frequent. very few studies have examined the effect of copd on outcomes in acs patients, and, to our knowledge, there has been no report on biomarkers that possibly mediate between copd and long-term acs patient outcomes. objectives: to determine the effect of copd on longterm outcomes in patients presenting to the emergency department (ed) with acs and to identify prognostic inflammatory biomarkers. methods: we performed a prospective cohort study enrolling acs patients from a single large tertiary center. hospitalized patients aged years or older with acs were interviewed and their blood samples were obtained. seven inflammatory biomarkers were measured, including interleukin- (il- ), c-reactive protein (crp), tumor necrosis factor-alpha (tnf-alpha), vascular cell adhesion molecule (vcam), e-selectin, lipoprotein-a (lp-a), and monocyte chemoattractant protein- (mcp- ). the diagnoses of acs and copd were verified by medical record review. annual telephone follow-up was conducted to assess health status and major adverse cardiovascular events (mace) outcomes, a composite endpoint including myocardial infarction, revascularization procedure, stroke, and death. background: aortic dissection (ad) is an uncommon life-threatening condition requiring prompt diagnosis and management. thirty-eight percent of cases are missed upon initial evaluation. the cornerstone of accurate diagnosis hinges on maintaining a high index of clinical suspicion for the various patterns of presentation. quality documentation that reflects consideration for ad in the history, exam, and radiographic interpretation is essential for both securing the diagnosis and for protecting the clinician in missed cases. objectives: we sought to evaluate the quality of documentation in patients presenting to the emergency department with subsequently diagnosed acute ad. methods: irb-approved, structured, retrospective review of consecutive patients with newly diagnosed non-traumatic ad from to . inclusion criteria: new ad diagnosis via ed. exclusion criteria: ad diagnosed at another facility; chronic, traumatic, or iatrogenic ad. trained/monitored abstractors used a standardized data tool to review ed and hospital medical records. descriptive statistics were calculated as appropriate. inter-rater reliability was measured. our primary performance measure was the prevalence of a composite of all three key historical elements ( . any back pain, . neurologic symptoms including syncope, and . sudden onset of pain.) in the attending emergency physician's documentation. secondary outcomes included documentation of: ad risk factors, pain quality, back pain at multiple locations, presence/absence of pulse symmetry, mediastinal widening on chest radiograph, and migratory nature of the pain. results: / met our inclusion/exclusion criteria. the mean age was . years; % were male, ( . %) were stanford a. ( %) presented with a chief complaint of chest pain. primary outcome measure: / ( . %; %ci = . , . ) documented the presence/ absence of all three key historical elements. [back pain = / ; . % ( . , . ); neuro symptoms = / ; % ( . , . ); sudden onset = / ; . % ( . , . ).] limitations: small number of confirmed ad cases. conclusion: in our cohort, emergency physician documentation of key historical, physical exam, and radiographic clues of ad is suboptimal. although our ed miss rate is lower than that which has been reported by previous authors, there is an opportunity to improve documentation of these pivotal elements at our institution. objectives: this study assessed the opinions of iem and gh fellowship program directors, in addition to recent and current fellows regarding streamlining the application process and timeline in an attempt to implement change and improve this process for program directors and fellows alike. methods: a total of current iem and gh fellowship programs were found through an internet search. an electronic survey was administered to current iem and gh fellowship directors, current fellows, and recent graduates of these programs. results: response rates were % (n = ) for program directors and % (n = ) for current and recent fellows. the great majority of current and recent fellows ( %) and program directors ( %) support transitioning to a common application service. similarly, % of current and recent fellows and % of program directors support instituting a uniform deadline date for applications. however, only % of recent/current fellows and % of program directors would support a formalized match process like nrmp. conclusion: the majority of fellows and program directors support streamlining the application for all iem and gh fellowship programs. this could improve the application process for both fellows and program directors, and ensure the best fit for the candidates and for the fellowship programs. in order to establish effective emergency care in rural sub-saharan africa, the unique practice demographics and patient dispositions must be understood. objectives: the objectives of this study are to determine the demographics of the first patients seen at nyakibale hospital's ed and assess the feasibility of treating patients in a rural district hospital ed in sub-saharan africa. methods: a descriptive cross-sectional analysis of the first consecutive patient visits in the ed's patient care log was reviewed by an unblinded abstractor. data collected included age, sex, condition upon discharge, and disposition. all authors discussed uncertainties and formed a consensus. descriptive statistics were performed. results: of the first patient visits, ( . %) occurred when the outpatient clinic was open. there were ( %) male visits. the average age was . years (sd ± . ). pediatric visits accounted for ( . %) patients, and ( . %) visits were for children under five years old. only one patient expired in the ed, and ( . %) were in good condition after treatment, as subjectively defined by the ed physicians. one person was transferred to another hospital. after treatment, ( %) patients were discharged home. of those admitted to an inpatient ward, ( . %) patients were admitted to medical wards, ( . %) to pediatrics, and ( %) to surgical. only six ( . %) patients went directly to the operating theatre. conclusion: this consecutive sample of patient visits from a novel rural district hospital ed in sub-saharan africa included a broad demographic range. after treatment, most patients were judged to be in ''good condition'', and over one third of patients could be discharged after ed management. this sample suggests that it is possible to treat patients in an ed in rural sub-saharan africa, even in cases where surgical backup and transfers to higher level of care are limited or unavailable. background: communication failures in clinical handoffs have been identified as a major preventable cause of patient harm. in italy, advanced prehospital care is provided predominantly by physicians who work on ambulances in teams with either nurses or basic rescuers. the hand-offs from prehospital physicians to hospital emergency physicians (eps) is especially susceptible to error with serious consequences. there are no studies in italy evaluating the communication at this transition in patient care. studying this, however, requires a tool that measures the quality of this communication. objectives: the purpose of this study is to develop and validate a tool for the evaluation of communication during the clinical handoff from prehospital to emergency physicians in critically ill patients. methods: several previously validated tools for evaluating communication in hand-offs were identified through a literature search. these were reviewed by a focus group consisting of eps, nurses, and rescuers, who then adapted and translated the australian isbar (identification, situation, background, assessment, recommendation), the tool most relevant to local practice. the italian isbar tool consists of the following elements: patient and provider identification; patient's chief complaint; patient's past medical history, medications, and allergies; prehospital clinical assessment (primary survey, illness severity, vital signs, diagnosis); treatment initiated and anticipated treatment plan. we conducted and video-taped the hand-offs of care from the prehospital physicians to the eps in pediatric critical care simulations. four physician raters were trained in the italian isbar tool and used it to independently assess communication in each simulation. to assess agreement we calculated the proportion of agreement among raters for each isbar question, fleiss' kappas for each simulation, as well as mean agreement and mean kappas with standard deviations. results: there was % agreement among the four physicians on % of the items. the mean level of agreement was % (sd . ). the overall mean kappa was . (sd . ). conclusion: the standardized tool resulted in good agreement by physician raters. this validated tool may be helpful in studying and improving hand-offs in the prehospital to emergency department setting. objectives: we hypothesized that residents who were provided with vps prior to hfs would perform more thoroughly and efficiently than residents who had not been exposed to the online simulation. methods: we randomized a group of residents from an academic, pgy - emergency medicine program to complete an online vps case, either prior to (vps group, n = residents) or after (n = ) their hfs case. the vps group had access to the online case (which reviewed asthma management) days prior to the hfs session. all residents individually participated in their regularly scheduled hfs and were blinded to the content of the case -a patient in moderate asthma exacerbation. the authors developed a dichotomous checklist consisting of items recorded as done/not done along with time completed. a two sample proportion test was used to evaluate differences in the individual items completed between groups. a wilcoxon rank sum test was used to determine the differences in overall and subcategory performance between the two groups. median time to completion was analyzed using the log-rank test. results: the vps group had better overall checklist performance than the control group (p-value . ). in addition, the vps group was more thorough in obtaining an hpi (p-value . ). specific actions (related to asthma management) were performed better by the vps group: inquiring about last/prior ed visits ( . ), total number of hospitalizations in the prior year ( . ), prior intubations ( . ), and obtaining peak flow measurements ( . ). overall there was no difference in time to event completion between the two groups. conclusion: we found that when hfs is primed with educational modalities such as vps there was an improvement in performance by trainees. however, the improved completeness of the vps group may have served as a barrier to efficiency, inhibiting our ability to identify a statistical significant efficiency overall. vps may aid in priming the learners and maximize the efficiency of training using high-fidelity simulations. training using an animal model helped develop residents' skills and confidence in performing ptv. retention was found to be good at months post-training. this study underscores the need for hands-on training in rare but critical procedures in emergency medicine. methods: in this cross-sectional study at an urban community hospital, residents in their second or third year of training from a -year em residency program performed us-guided catheterizations of the ij on a simulator manufactured by blue phantom. two board-certified em physicians observed for the completion of pre-defined procedural steps using a checklist and rated the residents' overall performance of the procedure. overall performance ratings were provided on a likert scale of to , with being poor and being excellent. residents were given credit for performing a procedural step if at least one rater marked its completion. agreement between raters was calculated using intraclass correlation coefficients for domain and summary scores. the same protocol was then repeated on an unembalmed cadaver using two different board-certified em physician raters. criterion validity of the residents' proficiency on the simulator was evaluated by comparing their median overall performance rating on the simulator to that on the cadaver and by comparing the proportion of residents completing each procedural step between modalities with descriptive statistics. results: em residents' overall performance rating on the simulator was . ( % ci: . to . ) and on the cadaver was . ( % ci: . to . ). the results for each procedural step are summarized in the attached figure. inter-rater agreement was high for assessments on both the simulator and cadaver with overall kappa scores of . and . respectively. background: the environment in the emergency department (ed) is chaotic. physicians must learn how to multi-task effectively and manage interruptions. noise becomes an inherent byproduct of this environment. previous studies in the surgical and anesthesiology literature examined the effect of noise levels and cognitive interruptions on resident performance during simulated procedures; however, the effect of noise distraction on resident performance during an ed procedure has not yet been studied. objectives: our aim was to prospectively determine the effects of various levels of noise distraction on the time to successful intubation of a high-fidelity simulator. methods: a total of emergency medicine, emergency medicine/internal medicine, and emergency medicine/family medicine residents were studied in a background noise environments of less than decibels (noise level ), - decibels (noise level ), and of greater than decibels (noise level ). noise levels were standardized by a dosimeter (ex tech instruments, heavy duty ). each resident was randomized to the order in which he or she was exposed to the various noise levels and had a total of minutes to complete each of the intubation attempts, which were performed in succession. time, in seconds, to successful intubation was measured in each of these scenarios with the start time defined as the time the resident picked up the storz c-mac video laryngoscope blade and the finish time defined as the time the tube passed through the vocal cords as visualized by an observer on the storz c-mac video screen. analytic methods included analysis of variance, student's t-test, and pearson's chi-square. results: no significant differences were found between time to intubation and noise level nor did the order of noise level exposure affect the time to intubation (see table) . there were no significant differences in success rate between the three noise levels (p = . ). a significant difference in time to intubation was found between the residents' second and third intubation attempts with decreased time to intubation for the third attempt (p = . ). conclusion: noise level did not have an effect on time to intubation or intubation success rate. time to intubation decreased between the second and third intubations regardless of noise level. background: growing use of the emergency department (ed) is cited as a cause of rising health care costs and a target of health care reform. eds provide approximately one quarter of all acute care outpatient visits in the us. eds are a diagnostic center and a portal for rapid inpatient admission. the changing role of eds in hospital admissions has not been described. objectives: to compare if admission through the ed has increased compared to direct hospital admission. we hypothesized that the use of the ed as the admitting portal increased for all frequently admitted conditions. methods: we analyzed the nationwide inpatient sample (nis), the largest us all-payer inpatient care database, from - . nis contains data from approximately million hospital stays each year, and is weighted to produce national estimates. we used an interactive, webbased data tool (hcupnet) to query the nis. clinical classification software (ccs) was used to group discharge diagnoses into clinically meaningful categories. we calculated the number of annual admissions and proportion admitted from the ed for the most frequently admitted conditions. we excluded ccs codes that are rarely admitted through the ed (< %) as well as obstet- background: the optimal dose of opioids for patients in acute pain is not well defined, although . mg/kg of iv morphine is commonly recommended. patient-controlled analgesia (pca) provides an opportunity to assess the adequacy of this recommendation as use of the pca pump is a behavioral indication of insufficient analgesia. objectives: to assess the need for additional analgesia following a . mg/kg dose of iv morphine by measuring additional self-dosing via a pca pump. methods: a three-arm randomized controlled trial was performed in an urban ed with , annual adult visits. a convenience sample of ed patients ages to with abdominal pain of < days duration requiring iv opioids was enrolled between / and / . all patients received an initial dose of . mg/kg iv morphine. patients in the pca arms could request additional doses of mg or . mg iv morphine by pressing a button attached to the pump with a -minute lock-out period. for this analysis, data from both pca arms were combined. software on the pump recorded times when the patient pressed the button (activation) and when he/she received a dose of morphine (successful activation). results: patients were enrolled in the pca arms. median baseline nrs pain score was . mean amount of supplementary morphine self-administered over the hour study period subsequent to the loading dose was . mg and . mg for the and . mg pca groups respectively. patients activated the pump at least once ( %, % ci: to %). figure shows the frequency distribution of the number of times the pump was activated. of those who activated the pump, the median number of activations per person was (iqr: to ). there were activations of the pump. % of activations were successful (followed by administration of morphine), while % were unsuccessful as they occurred during the -minute lock-out periods. % of the activations occurred in the first minutes, % in the second minutes, % in the third minutes, and % in the last minutes after the initial loading dose. conclusion: almost all patients requested supplementary doses of pca morphine, half of whom activated the pump five times or more over a course of hours. this frequency of pca activations suggests that the commonly recommended dose of . mg/kg morphine may constitute initial oligoanalgesia in most patients. marie-pier desjardins, benoit bailey, fanny alie-cusson, serge gouin, jocelyn gravel chu sainte-justine, montreal, qc, canada background: administration of corticosteroid at triage has been suggested to decrease the time to corticosteroid administration in the ed. objectives: to compare the time between arrival and corticosteroid administration in patients treated with an asthma pathway (ap) or with standard management (sm) in a pediatric ed. methods: chart review of children aged to years diagnosed with asthma, bronchospasm, or reactive airways disease seen in the ed of a tertiary care pediatric hospital. for a one year period, % of all visits were randomly selected for review. from these, we reviewed patients who were eligible to be treated with the ap ( ‡ months with previous history of asthma and no other pulmonary condition) and who had received at least one inhaled bronchodilator treatment. charts were evaluated by a data abstractor blinded to the study hypothesis using a standardized datasheet. various variables were evaluated such as age, respiratory rate and saturation at triage, type of physician who saw patient first, treatment prior to visit, in ed, and at discharge, time between arrival and corticosteroid administration, and length of stay (los background: return visits comprise . % of pediatric emergency department (ped) visits, at a cost of >$ million/year nationally. these visits are typically triaged with higher acuity and admission rates and raise concern for lapses in quality of care and patient education during the first visit. objectives: the aim of this qualitative study was to describe parents' reasons for return visits to the ped. methods: we prospectively recruited a convenience sample of parents of patients under the age of years who returned to the ped within hours of their previous visit. we excluded patients who were instructed to return, had previously left without being seen, arrived without a parent, were wards of the state, or did not speak english. after obtaining consent, the principal investigator (ce) conducted confidential, in-person, tape-recorded interviews with parents during ped return visits. parents answered open-ended questions and closed-ended questions using a five-point likert scale. responses to open-ended questions were analyzed using thematic analysis techniques. the scaled responses were grouped into three categories of agree, disagree, or neutral. results: from the closed-ended responses, % of parents agreed that their children were getting sicker, and % agreed that their children were not getting better. % agreed that they were unsure how to treat the illness, however only % agreed they did not feel figure : frequency distribution of number of pca activations comfortable taking care of the illness. only % agreed that the medical condition and/or the instructions were not clearly explained in the first visit. some common themes from the open-ended questions included worsening or lack of improvement of symptoms. many parents reported having unanswered questions about the cause of the illness and hoped to find out the cause during the return visit. conclusion: most parents brought their children back to the ped because they believed the symptoms had worsened or were not improving. although a large proportion of parents believed that the medical condition was clearly explained at the first visit, many parents still had unanswered questions about the cause of their child's illness. while worsening symptoms seemed to drive most return visits, it is possible that some visits related to failure to improve might be prevented during the first ped visit through a more detailed discussion of disease prognosis and expected time to recover. pediatric background: experience indicates that it is difficult to effectively quell many parents' anxiety toward pediatric fevers, making this a common emergency department (ed) complaint. the question remains as to whether athome treatment has any effect on the course of emergency department treatment or length of stay in this population. objectives: to determine whether anti-pyretic treatment prior to arrival in the emergency department affects the evaluation or emergency department length of stay of febrile pediatric patients. methods: a convenience sample of children, ages - years, who presented to a tertiary care ed with chief complaint of fever were enrolled. parents were asked to participate in an eight-question survey. questions related to demographic information, pre-treatment of the fever, contact with primary care providers prior to ed arrival, and immunization status. upon admission or discharge, investigators recorded information regarding length of stay, laboratory tests and imaging ordered, and medications given. results: eighty-one patients were enrolled in the study. seventy-six percent of the patients were pre-treated with some form of anti-pyretic by the caregiver prior to ed arrival. there was no significant effect of pre-treatment on whether laboratory tests or medications were ordered in the ed or whether the patient was admitted or discharged. the length of ed stay was found to be significantly shorter among those who received anti-pyretics prior to arrival ( ± vs. ± minutes; p = . ). conclusion: among febrile children, those who receive anti-pyretics prior to their ed visit had statistically significant shorter length of stays. this also supports implementation of triage or nursing protocols to administer an anti-pyretic as soon as possible in the hope of decreasing ed throughput times. background: during the past two decades, the prevalence of overweight (bmi percentile > ) in children has more than doubled, reaching epidemic proportions both nationally and globally. the public health burden is enormous given the increased risk of adult obesity as well as the adverse consequences on cardiovascular, metabolic, and psychological health. despite the overwhelming prevalence, the effect of obesity on emergency care has received little attention. objectives: the goal of this study is to determine the relation of weight on reported emergency department visits in children from a nationally representative sample. methods: weight (as reported by parents) and height along with frequency of and reason for emergency department (ed) use in the last months were obtained from children aged - y (n = , ) in the cross-sectional, telephone-administered, national survey of children's health (nsch). bmi percentiles were calculated using sex-specific bmi for age growth charts from the cdc ( ). children were categorized as: underweight (bmi percentile£ ), normal weight (> to < ), at-risk for overweight ( to < ), and overweight ( ‡ ). prevalence of ed use was estimated and compared across bmi percentile categories using chisquare analysis and multivariable logistic regression. taylor-series expansion was used for variance estimation of the complex survey design. results: the prevalence of at least one ed use in the past months increased with increasing bmi percentiles (figure , p < . ). additionally, overweight children were more likely to have more than one visit. overweight children were also less likely to report an injury, poisoning, or accident as the reason for ed visit compared to other bmi categories ( , , , % in overweight, at-risk, normal, and underweight respectively, p < . ). conclusion: as rates of childhood obesity continue to grow in the u.s., we can expect greater demands on the ed. this will likely translate into an increased emphasis on the care of chronic conditions rather than injuries and accidents in the pediatric ed setting. results: mean pediatric satisfaction score was . (sd . ) compared with . ( . ) for adult patients (p < . ); monthly sample sizes ranged from - and from - for the two populations, respectively. both populations showed an increase in satisfaction after opening of the ped-ed. for both populations there was no significant trend in patient satisfaction from the beginning of the study period to the opening of the ped-ed, but after the opening the models of the populations differed. the pediatric satisfaction model was an interrupted two-slope model, with an immediate jump of . points in november and an increase of . points per month thereafter. in contrast, adult satisfaction scores did not show a jump but increased linearly (two slope model) after / at a rate of . per month. prior to the opening of the ped-ed, mean monthly pediatric and adult satisfaction scores were . ( . ) and . ( . ), respectively (difference . % ci . - . , p = . ). after the opening the mean scores were . ( . ) and . ( . ), respectively (difference . , % ci . - . , p < . ). conclusion: opening of a dedicated ped-ed was associated with a significant increase in patient satisfaction scores both for children and adults. patient satisfaction for children, as compared to adults, was higher before and after opening a ped-ed. the background: there are racial disparities in outcomes among injured children. in particular, black race appears to be an independent predictor of mortality. objectives: to evaluate disparities among ed visits for unintentional injuries among children ages - . methods: five years of data ( ) ( ) ( ) ( ) ( ) from the national hospital ambulatory cares survey were combined. inclusion criteria were defined as unintentional injury visits (e-code . to . or . to . ) and age - years. visit rates per population (defined by the us census) were calculated by race and age group. weighted multivariate logistic regression analysis was performed to describe associations between race and specific outcome variables and related covariates. primary statistical analyses were performed using sas version . . . results: , , of , , weighted ed visits met our inclusion criteria ( . %). per persons, black children had . times as many ed visits for unintentional injuries as whites (table) . there were no racial differences in the sex ratio ( . boy visits: girl), proportion of visits by age, ed disposition, immediacy with which they needed to be seen, whether or not they were evaluated by an attending physician, metropolitan vs. rural hospital, admission length of stay, mode of transportation for ed arrival, number of procedures, diagnostic services, or ed medications. background: sudden cardiac arrests in schools are infrequent, but emotionally charged events. little data exist that describes aed use in these events. objectives: the purpose of our study was to ) describe characteristics and outcomes of school cardiac arrests (ca), and ) assess the feasibility of conducting bystander interviews to describe the events surrounding school ca. methods: we performed a telephone survey of bystanders to ca occurring in k- schools in communities participating in the cardiac arrest registry to enhance survival (cares) database. the study period was from / - / and continued in one community through . utstein style data and outcomes were collected from the cares database. a structured telephone interview of a bystander or administrative personnel was conducted for each ca. a descriptive summary was used to assess for the presence of an aed, provision of bystander cpr (bcpr), and information regarding aed deployment, training, and use and perceived barriers to aed use. descriptive data are reported. results: during the study period there were , ca identified at cares communities, of which were identified as educational institutions. of these, ( . %) events were at k- schools with ( . %) being high schools. of the arrests, a minority were children ( ( . %) < age ), most ( , . %) were witnessed, a majority ( , . %) received bcpr, and ( . %) were initially in ventricular fibrillation (vf). most arrests / ( %) occurred during the school day ( a- p). overall, ( . %) survived to hospital discharge. interviews were completed for of ( . %) k- events. eighteen schools had an aed on site. most schools ( . %) with aeds reported that they had a training program and personnel identified for its use. an aed was applied in of patients, and of these were in vf and survived to hospital discharge. multiple reasons for aed non-use (n = ) were identified. conclusion: cardiac arrests in schools are rare events; most patients are adults and received bcpr. aed use was infrequent, even when available, but resulted in excellent ( / ) survival. further work is needed to understand aed non-use. post-event interviews are feasible and provide useful information regarding cardiac arrest care. physician background: gastroenteritis is a common childhood disease accounting for - million annual pediatric emergency visits. current literature supports the use of anti-emetics reporting improved oral re-hydration, cessation of vomiting, and reduced need for iv re-hydration. however, there remains concern that using these agents may mask alternative diagnoses. objectives: to assess outcomes associated with use of a discharge action plan using ed-dispensed ondansetron at home in the treatment of gastroenteritis. methods: a prospective, controlled, observational trial of patients presenting to an urban pediatric emergency department (census , ) over a -month period for acute gastroenteritis. fifty patients received ondansetron in the ed. twenty-nine patients were enrolled in the pediatric emergency department discharge action plan (ped-dap) where ondansetron for home use was dispensed by the treating clinician. twenty-one patients were controls. control patients did not receive home ondansetron. ped-dap patients were given instructions to administer the ondansetron for ongoing symptoms any time hours post ed discharge. all patients were followed by phone at - days to assess for the following: time of emesis resolution, alternative diagnoses, unscheduled visits, and adverse events. results: all patients were followed by phone. / ped-dap patients received home ondansetron. / patients had resolution of emesis in the ed. / had resolution of their emesis between time of discharge and hours. / of ped-dap patients reported emesis after hours from ed discharge. five patients reported an unscheduled visit. all five return visits returned to the ed ( / returned for emesis, / for diarrhea). / controls reported resolution of symptoms within the ed. / of controls had resolution between time of discharge and hours. / of the control patients had resolution with between and hours post discharge. / had an unscheduled appointment with the pmd at hours post-discharge for ongoing fever and nausea. in follow-up there were no alternative diagnoses identified. the effect of the ped-dap on resolution of emesis between discharge and hours appears to be statistically significant (p value < . ). conclusion: ondansetron given in schedule with a discharge action plan appears to provide a modest benefit in resolution of symptoms relative to a control population. objectives: to determine the repeatability coefficient of a mm vas in children aged to years in different circumstances: assessments done either at or minute interval, when asked to recall their score or to reproduce it. methods: a prospective cohort study was conducted using a convenience sample of patients aged to years presenting to a pediatric ed. patients were asked to indicate, on a mm paper vas, how much they liked a variety of food with four different sets of three questions: (set ) questions at minute interval with no specific instruction other than how to complete the vas and no access to previous scores, (set ) same format as set except for questions at minute interval, (set ) same as set except patients were asked to remember their answers, and (set ) same as set except patients were shown their previous answers. for each set, the repeatability coefficient of the vas was determined according to the bland-altman method for measuring agreement using repeated measures: . x Ö x s w where s w is the within-subject standard deviation by anova. the sample size required to estimate s w to % of the fraction value as recommended was patients if we obtained three measurements for each patient. results: a total of patients aged . ± . years were enrolled. the repeatability coefficient for the questions asked at minute intervals was mm, and mm when asked at minute interval. when asked to remember their previous answers or to reproduce them, the repeatability coefficient for the questions was mm and mm, respectively. conclusion: the condition of the assessments (variation in intervals or patients asked to remember or to reproduce their previous answers) influence the testretest reliability of the vas. depending on circumstances, the theoretical test-retest reliability in children aged to years varies from to mm on a mm paper vas. background: skull radiographs are a useful tool in the evaluation of pediatric head trauma patients. however, there is no consensus on the ideal number of views that should be obtained as part of a standard skull series in the evaluation of pediatric head trauma patients. objectives: to compare the sensitivity and specificity of a two-and four-film x-ray series in the diagnosis of skull fracture in children, when interpreted by pediatric emergency medicine physicians. methods: a prospective, crossover experimental study was performed in a tertiary care pediatric hospital. the skull radiographs of children were reviewed. these were composed of the most recent cases of skull fracture for which a four-film radiography series was available at the primary setting and controls, matched for age. two modules, containing a random sequence of two-and four-film series of each child, were constructed in order to have all children evaluated twice (once with two films and once with four films). board-certified or -eligible pediatric emergency physicians evaluated both modules two to four weeks apart. the interpretation of the four-film series by a radiologist, or when available, the findings on ct scan, served as the gold standard. accuracy of interpretation was evaluated for each patient. the sensitivity and specificity of the two-film versus the four-film skull xray series, in the identification of fracture, were compared. this was a non-inferiority cross-over study evaluating the null hypothesis that a series with two views would have a sensitivity (specificity) that is inferior by no more than . compared to a series with four views. a total of controls and cases were needed to establish non-inferiority of the two-film series versus the four-film series, with a power of % and a significance level of %. results: ten pediatric emergency physicians participated in the study. for each radiological series, the proportion of accurate interpretation varied between . to . . the four-film series was found to be more sensitive in the detection of skull fracture than a two-film series (difference: . , %ci . to . ). however, there was no difference in the specificity (difference: . , %ci ) . to . ). conclusion: for children sustaining a head trauma, a four-film skull radiography series is more sensitive than a two-film series, when interpreted by pediatric emergency physicians. the objectives: we developed a free online video-based instrument to identify knowledge and clinical reasoning deficits of medical students and residents for pediatric respiratory emergencies. we hypothesized that it would be a feasible and valid method of differentiating educational needs of different levels of learners. methods: this was an observational study of a free, web-based needs assessment instrument that was tested on third and fourth year medical students (ms - ) and pediatric and emergency medicine residents (r - ). the instrument uses youtube video triggers of children in respiratory distress. a series of cased-based questions then prompts learners to distinguish between upper and lower airway obstruction, classify disease severity, and manage uncomplicated croup and bronchiolitis. face validity of the instrument was established by piloting and revision among a group of experienced educators and small groups of targeted learners. final scores were compared across groups using t-tests to determine the ability of the instrument to differentiate between different levels of learners (concurrent validity). cronbach's alpha was calculated as a measure of internal consistency. results: response rates were % among medical students and % among residents. the instrument was able to differentiate between junior (ms , ms , and r ) and senior (r , r ) learners for both overall mean score ( % vs. %, p < . ) and mean video portion score ( vs. %, p = . ). table compares results of several management questions between junior and senior learners. cronbach's alpha for the test questions was . . conclusion: this free online video-based needs assessment instrument is feasible to implement and able to identify knowledge gaps in trainees' recognition and management of pediatric respiratory emergencies. it demonstrates a significant performance difference between the junior and senior learners, preliminary evidence of concurrent validity, and identifies target groups of trainees for educational interventions. future revisions will aim to improve internal consistency. results: the survey response rate was % ( / ). among responding programs, ( %) reside within a children's hospital (vs. general ed); ( %) are designated level i pediatric trauma centers. forty-three ( %) programs accept - pem fellows per year; ( %) provided at least some eus training to fellows, and ( %) offer a formal eus rotation. on average this training has existed for ± years and the mean duration of eus rotations is ± weeks. twenty-eight ( %) programs with eus rotations provide fellow training in both a general ed and a pediatric ed. there were no hospital or program level factors associated with having a structured training program for pem fellows. conclusion: as of , the majority of pem fellowship programs provide eus training to their fellows, with a structured rotation being offered by most of these programs. background: ed visits are an opportunity for clinicians to identify children with poor asthma control and intervene. children with asthma who use eds are more likely than other children to have poor control, not be using controller medications, and have less access to traditional sources of primary care. one significant barrier to ed-based interventions is recognizing which children have uncontrolled asthma. objectives: to determine whether the pacci, a item parent-administered questionnaire, can help ed clinicians better recognize patients with the most uncontrolled asthma and differentiate between intermittent and persistent asthma. methods: this was a randomized controlled trial performed at an urban pediatric ed. parents were asked to answer questions about their child's asthma including drug adherence and history of exacerbations, as well as answer demographic questions. using a convenience sample of children - years presenting with an asthma exacerbation, attending physicians in the study were asked to complete an assessment of asthma control. physicians were randomized to receive a completed pacci (intervention) or not (control group). using an intent-to-treat approach, clinicians' ability to accurately identify ) four categories of control used by the national heart, lung, and blood institute (nhlbi) asthma guidelines, ) intermittent vs. persistent level asthma, and ) controlled / mildly uncontrolled vs. moderate/severely uncontrolled asthma were compared for both groups using chi-square analysis. results: between january and august , patients were enrolled. there were no statistically significant differences between the intervention and control groups for child's sex, age, race and parents' education. conclusion: the pacci improves ed clinicians' ability to categorize children's asthma control according to nhlbi guidelines, and the ability to determine when a child's control has been worsening. ed clinicians may use the pacci to identify those children in greatest need for intervention, to guide prescription of controller medications, and communicate with primary care providers about those children failing to meet the goals of asthma therapy. figure) . fewer than half of physicians reported the parent of a -year-old being discharged from their ed following an mvc-related visit would receive either child passenger safety information or referrals (table) . conclusion: emergency physician report of child passenger safety resource availability is associated with trauma center designation. even when resources are available, referrals from the ed are infrequent. efforts to increase referrals to community child passenger safety resources must extend to the community ed settings where the majority of children receive injury care. background: pediatric subspecialists are often difficult to access following ed care especially for patients living far from providers. telemedicine (tm) can potentially eliminate barriers to access related to distance, and cost. objectives: to evaluate the overall resource savings and access that a tm program brings to patients and families. methods: this study took place at a large, tertiary care regional pediatric health care system. data were collected from / - / . metrics included travel distance saved (round trip between tm presenting sites and the location of the receiving sites), time savings, direct cost savings (based on $ . /mile) and potential work and school days saved. indirect costs were calculated as travel hrs saved/encounter (based on an average speed of miles/hr). demographics and services provided were included. results: tm consults were completed by separate pediatric subspecialty services. most patients were school aged ( % >/= yrs old objectives: to analyze test characteristics of the pathway and its effects on ed length of stay, imaging rates, and admission rate before versus after implementation. methods: children ages - presenting to one academic pediatric ed with suspicion for appendicitis from october -august were prospectively enrolled to a pathway using previously validated lowand high-risk scoring systems. the attending physician recorded his or her suspicion of appendicitis and then used one of two scoring systems incorporating history, physical exam, and cbc. low-risk patients were to be discharged or observed in the ed. high-risk patients were to be admitted to pediatric surgery. those meeting neither low-nor high-risk criteria were evaluated in the ed by pediatric surgery, with imaging at their discretion. chart review and telephone follow-up were conducted two weeks after the visit. charts of a random sample of patients with diagnoses of acute appendicitis or chief complaint of abdominal pain and undergoing a workup for appendicitis in the eight months before and after institution of the pathway were retrospectively reviewed by one or two trained abstractors. results: appendicitis was diagnosed in of patients prospectively enrolled to the pathway ( %). mean age was . years. of those with appendicitis, were not low-risk (sensitivity . %, specificity . %). the high-risk criteria had a sensitivity of . % and specificity of . %. a priori attending physician assessment of low risk had a sensitivity of % and specificity of . %. a priori assessment of high risk had a sensitivity of . % and specificity of . %. we reviewed visits prior to the pathway and after. mean ed length of stay was similar ( minutes before versus after). ct was used in . % of visits before and . % after (p = . ). use of ultrasound increased ( . % before versus . % after, p < . ). admission rates were not significantly different ( . % before versus . % after, p = . ). conclusion: the low-risk criteria had good sensitivity in ruling out appendicitis and can be used to guide physician judgment. institution of this pathway was not associated with significant changes in length of stay, utilization of ct, or admission rate in an academic pediatric ed. computer-delivered alcohol and driver safety behavior screening and intervention program initiated during an emergency department visit mary k. murphy , lucia l. smith , anton palma , david w. lounsbury , polly e. bijur , paul chambers yale university, new haven, ct; albert einstein college of medicine, bronx, ny background: alcohol use is involved in percent of all fatal motor vehicle crashes and recent estimates show that at least , people were injured due to distracted driving last year. patients who visit the emergency department (ed) are not routinely screened for driver safety behavior; however, large numbers of patients are treated in the ed every day creating an opportunity for screening and intervention on important public health behaviors. objectives: to evaluate patient acceptance and response to a computer-based traffic safety educational intervention during an ed visit and one month follow-up. methods: design. pre /post educational intervention. setting. large urban academic ed serving over , patients annually. participants. medically stable adult ed patients. intervention. patients completed a self-administered, computer-based program that queried patients on alcohol use and risky driving behaviors (texting, talking, and other forms of distracted driving). the computer provided patients with educational information on the dangers of these behaviors and collected data on patient satisfaction with the program. staff called patients one month post ed visit for a repeat query. results: patients participated; average age ( - ), % hispanic, % male. % of patients reported the program was easy to use and were comfortable receiving this education via computer during their ed visit. self-reported driver safety behaviors pre, post intervention (% change): driving while talking on the phone %, % () %, p = . ), aggressive driving %, % () %, p = . ), texting while driving %, % () %, p = . ), driving while drowsy %, % () %, p = . ), drinking in excess of nih safe drinking guidelines %,% () %, p = . ), drinking and driving %, % () %, p = . ). conclusion: we found a high prevalence of selfreported risky driving behaviors in our ed population. at month follow-up, patients reported a significant decrease in these behaviors. overall patients were very satisfied receiving educational information about these behaviors via computer during their ed visit. this study indicates that a low-intensity, computer-based educational intervention during an ed visit may be a useful approach to educate patients about safe driving behaviors and promote behavior change. prevalence of depression among emergency department visitors with chronic illness janice c. blanchard, benjamin l. bregman, jeffrey smith, mohammad salimian, qasem al jabr george washington university, washington, dc background: persons with chronic illnesses have been shown to have higher rates of depression than the general population. the effect of depression on frequent emergency department (ed) use among this population has not been studied. objectives: this study evaluated the prevalence of major depressive disorder (mdd) among persons presenting with depression to the george washington university ed. we hypothesized that patients with chronic illnesses would be more likely to have mdd than those without. methods: this was a single center, prospective, crosssectional study. we used a convenience sample of noncritically ill, english-speaking adult patients presenting with non-psychiatric complaints to an urban academic ed over months in . subjects were screened with the phq , a nine-item questionnaire that is a validated, reliable predictor of mdd. we also queried respondents about demographic characteristics as well as the presence of at least one chronic disease (heart disease, hypertension, asthma, diabetes, hiv, cancer, kidney disease, or cerebrovascular disease). we evaluated the association between mdd and chronic illnesses with both bivariate analysis and multivariate logistic regression controlling for demographic characteristics (age, race, sex, income, and insurance coverage). results: our response rate was . % with a final sample size of . of our total sample, ( . %) had at least one of the chronic illnesses defined above. of this group, ( . %) screened positive for mdd as compared to ( . %) of the group without chronic illnesses (p < . ). in multivariate analysis, persons with chronic illnesses had an odds ratio for a positive depression screen of . ( . , . ) as compared to persons without illness. among the subset of persons with chronic illnesses (n = ), . % had ‡ visits in the prior days as compared to . % of persons with chronic illnesses without mdd (p = . ). conclusion: our study found a high prevalence of untreated mdd among persons with chronic illnesses who present to the ed. depression is associated with more frequent emergency department use among this population. initial blood alcohol level aids ciwa in predicting admission for alcohol withdrawal craig hullett, douglas rappaport, mary teeple, daniel butler, arthur sanders university of arizona, tucson, az background: assessment of alcohol withdrawal symptoms is difficult in the emergency department. the clinical institute withdrawal assessment (ciwa) is commonly used, but other factors may also be important predictors of withdrawal symptom severity. objectives: the purpose of this study is to determine whether ciwa score at presentation to triage was predictive of later admission to the hospital. methods: a retrospective study of patients presenting to an acute alcohol and drug detoxification hospital was performed from july through january . patients were excluded if other drug withdrawal was present in addition to alcohol. initial assessment included age, sex, vital signs, and blood alcohol level (bal) in addition to hourly ciwa score. admission is indicated for a ciwa score of or higher. data were analyzed by selecting all patients not immediately admitted at initial presentation. logistic regression using wald's criteria for stepwise inclusion was used to determine the utility of the initially gathered ciwa, bal, longest sobriety, liver cirrhosis, and vital signs in predicting subsequent admission. results: there were patients who fit the inclusion criteria, with admitted for treatment at initial intake and another admitted during the following hours. logistic regression indicated that presenting bal was a strong predictor (p = . ) of admission for treatment after initial presentation, as was presenting ciwa (p = . ). thus, presenting bal provided a substantial addition above initial ciwa in predicting later admission. no other variables added significantly to the prediction of later admission. to determine the interaction between presenting bal and ciwa scores, we ran a repeated measures analysis of the first five ciwa scores (from presentation to hours later), using bal split into low (bal < . ) and high (bal > . ) groups (see figure) . their interaction was significant, f ( , ) = . , p < . , g = . . those presenting with higher initial bal had suppressed ciwa scores that rose precipitously as the alcohol cleared. those with low presenting bal showed a decline in ciwa over time conclusion: initial assessment using the common assessment tool ciwa is aided significantly by bal assessment. patients with higher presenting bal are at higher risk for progression to serious alcohol withdrawal symptom. objectives: to describe patient and visitor characteristics and perspectives on the role of visitors in the ed and determine the effect of visitors on ed and hospital outcome measures. methods: this cross-sectional study was done in an , -visit urban ed, and data were attempted to be collected from all patients over a consecutive -hour period from august to , . trained data collectors were assigned to the ed continuously for the study period. patients assigned to a rapid care section of the ed ( %) were excluded. a visitor was defined as a person other than a health care provider (hcp) or hospital staff present in a patient's room at any time. patient perspectives on visitors were assessed in the following domains: transportation, emotional support, physical care, communication, and advocating for the patient. ed and hospital outcome measures pertaining to ed length of stay (los) and charges, hospital admission rate, hospital los and charges were obtained from patient medical records and hospital billing. data analyses included frequencies, student's t-tests for continuous variables, and chi-square tests of association for categorical variables. all tests for significance were two-sided. objectives: to examine the effect of sunday alcohol availability on ethanol-related visits and alcohol withdrawal visits to the ed. methods: study design was a retrospective beforeafter study using electronically archived hospital data at an urban, safety net hospital. all adult non-prisoner ed visits from / / to / / were analyzed. an ethanol-related ed visit was defined by icd- codes related to alcohol ( .x, .x, . , . ). an alcohol withdrawal visit was defined by icd- codes of delirium tremens ( . ), alcohol psychosis with hallucination ( . ), and ethanol withdrawal ( . ). we generated a ratio of ethanol-related ed visits to total ed visits (ethanol/total) and ratio of alcohol withdrawal ed visits to total ed visits (withdrawal/total). a day was redefined as am to am. the ratios were averaged within the four seasons to account for seasonal variations. data from summer were dropped as it spanned the law change. we stratified data into sunday and non-sunday days prior to analysis to isolate the effects of the law change. we used multivariable linear regression to estimate the association of the ratio with the law change while adjusting for time and the seasons. each ratio was modeled separately. the interaction between time and the law change was assessed using p < . . results: during the study there were a total of , ed visits including , ( % of total) ethanol-related visits and , ( % of total) alcohol withdrawal visits. unadjusted ratios in seasonal blocks are plotted in the figure with associated % ci and best fit regression line for before and after law change, respectively. after adjusting for time and season in the multivariable linear regression, we found no significant association of either ethanol/total or withdrawal/total with the law change. this remained true for both sunday and non-sunday data. all interactions assessed were not significant. conclusion: the change in colorado law to allow the sale of full-strength alcoholic beverages on sundays did not significantly affect ethanol-related or alcohol withdrawal ed visits. background: olanzapine is a second-generation antipsychotic (sga) with actions at the serotonin/histamine receptors. post-marketing reports and a case report have documented dangerous lowering of blood pressure when this antipsychotic is paired with benzodiazepines, but a recent small study found no bigger decreases in blood pressure compared to another antipsychotic like haloperidol. decreases in oxygen saturations, however, were larger when olanzapine was combined with benzodiazepines in alcohol-intoxicated patients. it is unclear whether these vital sign changes are associated with the intramuscular (im) route only. objectives: the assessment of vital signs following administration of either oral (po) or im olanzapine, either with or without benzodiazepines (benzos) and with or without concurrent alcohol intoxication. methods: this is a structured retrospective chart review of all patients who received olanzapine in an academic medical center ed from - who had vital signs documented both before medication administration and within four hours afterwards. vital signs were calculated as pre-dose minus lowest post-dose vital sign within hours, and were analyzed in an anova with route (im/po), benzo use (+/)), and alcohol use (+/)) as factors. significance level was set to < . . results: there were patients who received olanzapine over the study period. a total of patients ( po, im) met inclusion criteria. systolic blood pressures decreased across all groups as patients reduced their agitation. neither the route of administration, concurrent use of benzos, nor the use of alcohol were associated with significant changes in systolic bp (p = ns for all comparisons; see figure ). decreases in oxygen saturations, however, were significantly larger for alcoholintoxicated patients who subsequently received im olanzapine + benzos compared to other groups (route: p < . ; alcohol: p < . ; route x alcohol: p < . ; route x benzos x alcohol: p < . ; see figure ). conclusion: alcohol and benzos are not associated with significant decreases in blood pressure after po olanzapine, but im olanzapine + benzos is associated with potentially significant oxygen desaturations in patients who are intoxicated. intoxicated patients may have differential effects with the use of im sgas such as olanzapine when combined with benzos, and should be studied separately in drug trials. patients with a psychiatric diagnosis rasha buhumaid, jessica riley, janice blanchard george washington university, washington, dc background: literature suggests that frequent emergency department (ed) use is common among persons with a mental health diagnosis. few studies have documented risk factors associated with increased utilization among this population. objectives: to understand demographic characteristics of frequent users of the emergency department and describe characteristics associated with their visits. it was hypothesized that frequent visitors would have a higher rate of medical comorbidities than infrequent visitors. methods: this was a retrospective study of patients presenting to an urban, academic emergency department in . a cohort of all patients with a mental health-related final icd- coded diagnosis (axis i or axis ii) was extracted from the electronic medical record. using a standard abstraction form, a medical chart review collected information about medical comorbidities, substance abuse, race, age, sex, and insurance coverage, as well as diagnosis, disposition, and time of each visit. results: our sample consisted of frequent users ( ‡ visits in a day period) and infrequent users (£ visits in a day period). frequent users were more likely to be male ( % vs. . % p = . ), black ( % vs. % p < . ), and had a higher average number of comorbid conditions ( . , %ci . , . ) as compared to infrequent users ( . , %ci . , . ). a higher percentage of visits in the infrequent user group occurred during the day ( % vs. . % p < . ) while a higher number of visits in the frequent users occurred after midnight ( . % vs. . % p = . ). visits in the frequent user group were less likely to be for a psychiatric complaint ( . % vs. . %) and less likely to result in a psychiatric admission ( . % versus . %) as compared to the infrequent user group (p < . ). conclusion: our data indicate that among patients with psychiatric diagnoses, those who make frequent ed visits have a higher rate of comorbid conditions than infrequent visitors. despite their increased use of the ed, frequent visitors have a significantly lower psychiatric admission rate. many of the visits by frequent users are for non-psychiatric complaints and may reflect poor access to outpatient medical and mental health services. emergency departments should consider interventions to help address social and medical issues among mental health patients who frequently use ed services. background: the world health organization estimates that one million people die annually by suicide. in the u.s., suicide is the fourth leading cause of death between the ages of and . many of these patients are seen in ed, while outpatient visits for depression are also high. no recent analysis has compared these groups in the recent years. objectives: to determine if there is a relationship between the incidence of suicidal and depressed patients presenting to emergency departments and the incidence of depressed patients presenting to outpatient clinics from - . the secondary objective is to analyze trends in suicidal patients in the ed. methods: we used nhamcs (national hospital ambulatory medical care survey) and namcs (national ambulatory medical care survey), national surveys completed by the centers for disease control, which provide a sampling of emergency department and outpatient visits respectively. for both groups, we used mental-health-related icd- -cm, e codes and reasons for visit. we compared suicidal and depressed patients who presented to the ed, to those who presented to outpatient clinics. our subgroup analyses included age, sex, race/ethnicity, method of payment, regional variation, and urban verses rural distribution. results: ed visits for depression ( . %) and suicide attempts ( . %) remained stable over the years, with no significant linear trend. however, office visits for depression significantly decreased from . % of visits in to . % of visits in . non-latino whites had a higher percentage of ed visits for depression ( . %) and suicide attempt ( . %) (p < . ), and a higher percentage of office visits for depression than all other groups. among patients age - years, ed visits for suicide attempt significantly increased from . % in to . % in . homeless patients had a higher percent of ed visits for depression ( . %) and suicide attempt ( background: for potentially high-risk ed patients with psychiatric complaints, efficient ed throughput is key to delivering high-quality care and minimizing time spent in an unsecured waiting room. objectives: we hypothesized that adding a physician in triage would improve ed throughput for psychiatric patients. we evaluated the relationship between the presence of an ed triage physician and waiting room (wr) time, time to first physician order, time to ed bed assignment, and time spent in an ed bed. methods: the study was conducted from / - / at an academic ed with annual visits and a dedicated on-site emergency psychiatric unit. we performed a pre/post retrospective observational cohort study using administrative data, including weekend visits from noon- pm, months pre and post addition of weekend triage physicians. after adjusting for patient age, sex, insurance status, emergency severity index score, mode of arrival, ed occupancy rate, wr count, boarding count, and average wr los, multiple linear regression evaluated the relationship between the presence of a triage physician and four ed throughput outcomes: time spent in the wr, time to first order, time spent in an ed bed, and the total ed los. results: visits met inclusion criteria, in the months before and in the months after physicians were assigned to triage on weekends. table reports demographic data; multivariate analysis results are found in table . the presence of a triage physician was associated with an ( % ci . - . ) minute increase in wr time and no associated change in time to first order, time spent in an ed bed, or in the overall ed los. conclusion: use of triage physicians has been reported to decrease the time patients spend in an ed bed and improve ed throughput. however, for patients with psychiatric complaints, our analysis revealed a slight increase in wr time without evident change in the time to first order, time spent in an ed bed, or total ed los. improvements in ed throughput for psychiatric patients will likely require system-level changes, such as reducing ed boarding and improving lab efficiency to speed the process of medical clearance and reduce time spent in the unsecured wr. these findings may not be generalizable to eds without a dedicated ed psychiatric unit with full-time social workers to assist with disposition. initial assessment included ciwa scoring, repeated hourly, as well as other variables (see table ). treatment and admission to the inpatient hospital was indicated for a ciwa score of or higher. statistical analysis was performed utilizing repeated measures general linear modeling for ciwa scores and anova for all other variables. results: there were patients who fit the inclusion criteria, with admitted for treatment at initial intake and another admitted during the following hours. the table below compares the three most prevalent ethnic populations seen at our hospital. native americans presented at a significantly younger age (p < . ) than the other two ethnicities. initial ciwa scores taken on admission were significantly lower in the native american group than the other two groups (p < . ) and at hour a difference existed but failed to reach significance. repeated measures analysis indicate that ciwa scores progressed in a u-shaped curvilinear fashion (see figure ) conclusion: initial assessment utilizing ciwa scores appears to be affected by ethnicity. care must be taken when assessing and making decisions on a single initial ciwa score. further research is needed in this area as our numbers are small and differences might be seen in subsequent scoring. in addition, our study consists of primarily male patients and does not include african-american patients. background: age is a risk factor for adverse outcomes in trauma, yet evidence supporting the use of specific age cut-points to identify seriously injured patients for field triage is limited. objectives: to evaluate under-triage by age, empirically examine the association between age and serious injury for field triage, and assess the potential effect of mandatory age criteria. methods: this was a retrospective cohort study of injured children and adults transported by ems agencies to hospitals in regions of the western u.s. from - . hospital records were probabilistically linked to ems records using trauma registries, emergency department data, and state discharge databases. serious injury was defined as an injury severity score (iss) ‡ (the primary outcome). we assessed under-triage (triage-negative patients with iss ‡ ) by age decile, different mandatory age criteria, and used multivariable logistic regression models to test the association (linear and non-linear) between age and iss ‡ , adjusted for important confounders. results: , injured patients were evaluated and transported by ems over the -year period. under-triage increased markedly for patients over years, reaching % for those over years ( figure ). mandatory age triage criteria decreased under-triage, while substantially increasing over-triage: one iss ‡ patient identified for every additional patients triaged to major trauma centers. among patients not identified by other criteria, age had a strong non-linear association with iss ‡ (p < . ); the probability of serious injury steadily increased after years, becoming more notable after years ( figure ). conclusion: under-triage in trauma increases in patients over years, which may be reduced with mandatory age criteria at the expense of system efficiency. among patients not identified by other criteria, serious injury steadily increased after years, though there was no age at which risk abruptly increased. background: although limited resuscitation with hemoglobin-based oxygen carriers (hbocs) improves survival in several polytrauma models, including those of traumatic brain injury (tbi) with uncontrolled hemorrhage (uh) via liver injury, their use remains controversial. objectives: we examine the effect of hboc resuscitation in a swine polytrauma model with uh by aortic tear +/) tbi. we hypothesize that limited resuscitation with hboc would offer no survival benefit and would have similar effects in a model of uh via aortic tear +/) tbi. methods: anesthetized swine subjected to uh inflicted via aortic tear +/) fluid percussion tbi underwent equivalent limited resuscitation with hboc, lr, or hboc+nitroglycerin (ntg) (vasoattenuated hboc) and were observed for hours. comparisons were between tbi and no-tbi groups with adjustment for resuscitation fluid type using two-way anova with interaction and tukey kramer adjustment for individual comparisons. results: there was no independent effect of tbi on survival time after adjustment for fluid type (anova, tbi term p = . ) and there was no interaction between tbi and resuscitation fluid type (anova interaction term p = . ). there was a significant independent effect of fluid type on survival time (anova p = . background: intracranial hemorrhage (ich) after a head trauma is a problem frequently encountered in the ed. an elevated inr is recognized as a risk of bleeding. however, in a patient with an inr in normal range, a level associated with a lower risk of ich is not known. objectives: the aim of this study was to identify an inr threshold that could predict a decreased risk of an ich after a head trauma in patients with a normal inr. it is hypothesized that there is a threshold at which the likelihood of bleeding decreases significantly. methods: we did a study using data from a registry of patients with mild to severe head trauma (n = ) evaluated in a level i trauma center in canada between march and february . all the patients with a documented scan interpreted by a radiologist and a normal inr, defined as a value less then . , were included. we determined the correlation between inr value binned by . and the proportion of patients with an ich. threshold was defined by consensus as an abrupt change of more than % in the percentage of patients with ich. univariate frequency distribution was tested with pearson's chisquare test. logistic regression analysis was then used to study the effects of inr on ich with the following confounding factors: age, sex, and intake of warfarin, clopidogrel, or aspirin. results are presented with % confidence intervals. results: patients met the inclusion criteria. the mean age was . years ± . and % were men. patients ( . %) had an ich on brain scan. we found a significantly lower risk of ich at a threshold of inr less than . (p < . , univariate or = . , %ci . - . ) and a strong correlation between the risk of bleeding for every increase of the inr (r = . ). in fact, after adjustment for confounding variables, every . inr increase was associated with an increased risk of having an ich (or . ; % ci . - . ). conclusion: we were able to demonstrate an inr threshold under which the probability of ich was significantly lower. we also found a strong association between the risk of bleeding and the increase in inr within a normal range, suggesting that clinicians should not be falsely reassured by a normal inr. our results are limited by the fact that this is a retrospective study and a small proportion of traumatic brain injured patients in our database had no scan or inr at their ed visit. a prospective cohort study would be needed to confirm our results. background: increasingly, patients with tbi are being seen and managed in the emergency neurology setting. knowing which early signs are associated with prognosis can be helpful in directing the acute management. objectives: to determine whether any factors early in the course of head trauma are associated with shortterm outcomes including inpatient admission, in-hospital mortality, and return to the hospital within days. methods: this irb-approved study is a retrospective review of patients head injury presenting to our tertiary care academic medical center during a -month period. the dataset was created using redcap, a data management solution hosted by our medical school's center for translational science institute. results: the median age of the cohort (n = ) was , iqr = - yrs, with % being male. % had a gcs of - (mild tbi), % - (moderate tbi), and % gcs < (severe tbi). % of patients were admitted to the hospital. the median length of hospital stay was days, with an iqr of - days. of those admitted, % had an icu stay as well. the median icu los was also days, with an iqr of - days. twenty nine ( %) patients died during their hospital stay. lower gcs was predictive of inpatient admission (p = . ) as well as icu days (p < . ). significant predictors of re-admission to the hospital within days included hypotension (p = . ) upon initial presentation. the prehospital and ed gcs scores were not statistically significant. significant predictors of in-hospital death in a model controlling for age included bradycardia (p = . ), hyperglycemia (p = . ), and lower gcs (p = . ). the incidence of bradycardia (hr < ) was . %. conclusion: early hypotension, hyperglycemia, and bradycardia along with lower initial gcs are associated with significantly higher likelihood of hospital admission, including icu admission, as well as intrahospital death and re-admission. background: over , people per day require treatment for ankle sprains, resulting in lost workdays and training for athletes. platelet rich plasma (prp) is an autologous concentration of platelets which, when injected into the site of injury, is thought to improve healing by promoting inflammation through growth factor and cytokine release. studies to date have shown mixed results, with few randomized or placebo-controlled trials. the lower extremity functional scale (lefs) is a previously validated objective measure of lower extremity function. objectives: is prp helpful in acute ankle sprains in the the emergency department? methods: prospective, randomized, double-blinded, placebo-controlled trial. patients with severe ankle sprains and negative x-rays were randomized to trial or placebo. severe was defined as marked swelling and ecchymosis and inability to bear weight. both groups had cc of blood drawn. trial group blood was centrifuged with a magellan autologous platelet separator (arteriocyte, cleveland) to yield - cc of prp. prp along with . cc of % lidocaine and . cc of . % bupivicaine was injected at the point of maximum tenderness by a blinded physician under ultrasound guidance. control group blood was discarded and participants were injected in a similar fashion substituting sterile . % saline for prp. both groups had visual analog scale (vas) pain scores and lefs on days , , , and . all participants had a posterior splint and were made non weight bearing for days after which they were reexamined, had their splint removed, and were asked to bear weight as tolerated. participants were instructed not to use nsaids during the trial. results: patients were screened and were enrolled. four withdrew before prp injection was complete. eighteen were randomized to prp and to placebo. see tables for results. vas and lefs are presented as means with sd in parentheses. demographics were not statistically different between groups. conclusion: in this small study, prp did not appear to offer benefit in either pain control or healing. both groups had improvement in their pain and functionality and did not differ significantly during the study period. limitations include small study size and large number of participant refusals. methods: a structured chart review of all icd- radius fracture coded charts spanning march , to july , was conducted. specific variable data were collected and categorized as follows: age, moi, body mass index, and fracture location. the charts were reviewed by two medical students, with % of the charts reviewed by both students to confirm inter-rater reliability. frequencies and inter-quartile ranges were determined. comparisons were made with fisher's exact test and multiple logistic regression. results: charts met inclusion criteria. charts were excluded due to one of the following reasons: no fracture or no x-ray ( ), isolated ulnar fracture ( ), or undocumented or penetrating moi ( ). of the analyzed patients (n = ), distal radius fractures were most common ( %), followed by proximal ( %) and midshaft ( %). chart reviewers were found to be reliable (j = ). age and moi were significantly associated with fracture location (see table) . ages - and bike accidents were more strongly associated with proximal radius fractures (odds ratio: [ - ] and [ - ], respectively). conclusion: patients presenting to our inner city ed with a radius fracture are more likely to have a distal fracture. adults - and bike accidents had a significantly higher incidence of proximal fractures than other ages or mois. background: trauma centers use guidelines to determine the need for a trauma surgeon in the ed on patient arrival. a decision rule from loma linda university that includes penetrating injury and tachycardia was developed to predict which pediatric trauma patients require emergent intervention, and thus are most likely to benefit from surgical presence in the ed. objectives: our goal was to validate the loma linda rule (llr) in a heterogeneous pediatric trauma population and to compare it to the american college of surgeons' major resuscitation criteria (mrc). we hypothesized that the llr would be more sensitive than the mrc for identifying the need for emergent operative or procedural intervention. methods: we performed a secondary analysis of prospectively collected trauma registry data from two urban level i pediatric trauma centers with a combined annual census of approximately , visits. consecutive patients < years old with blunt or penetrating trauma from through were included. patient demographics, injury severity scores (iss), times of ed arrival and surgical intervention, and all variables of both rules were obtained. the outcome (emergent operative intervention within hour of ed arrival or ed cricothyroidotomy or thoracotomy) was confirmed by trained, blinded abstractors. sensitivities, specificities, and % confidence intervals (cis) were calculated for both rules. results: , patients were included with a median age of . years and a median iss of . emergent intervention was required in patients ( . %). the llr had a sensitivity ranging from . %- . % ( % ci: . %- . %) and specificity ranging from . %- . % ( % ci: . %- . %) between both institutions. the mrc had a sensitivity ranging from . %- . % ( % ci: . %- . %) and specificity ranging from . %- . % ( % ci: . %- . %) between institutions. conclusion: emergent intervention is rare in pediatric trauma patients. the mrc was more sensitive for predicting the need for emergent intervention than the llr. neither set of criteria was sufficiently accurate to recommend their routine use for pediatric trauma patients. droperidol for sedation of acute behavioural disturbance leonie a. calver , colin page , michael downes , betty chan , geoffrey k. isbister calvary mater newcastle and university of newcastle, newcastle, australia; princess alexandra hospital, brisbane, australia; calvary mater newcastle, newcastle, australia; prince of wales hospital, sydney, australia background: acute behavioural disturbance (abd) is a common occurrence in the emergency department (ed) and is a risk to staff and patients. there remains little consensus on the most effective drug for sedation of violent and aggressive patients. prior to the food and drug administration's black box warning, droperidol was commonly used and was considered safe and effective. objectives: this study aimed to investigate the effectiveness of parenteral droperidol for sedation of abd. methods: as part of a prospective observational study, a standardised protocol using droperidol for the seda-acute and delayed behavioral deficits were demonstrated in this rat model of co toxicity, which parallels the neurocognitive deficit pattern observed in humans (see figure) . similar to prior studies, pathologic analysis of brain tissue demonstrated the highest percentage of necrotic cells in the cortex, pyramidal cells, and cerebellum. the collected data are summarized in the table. we have developed an animal model of severe co toxicity evidenced by behavioral deficits and neuronal necrosis. future efforts will compare neurologic outcomes in severely co poisoned rats treated with hypothermia and % inspired o versus hbo to normothermic controls treated with % inspired o . increasing in popularity, attracting more than , annual participants worldwide. prior studies have consistently documented renal function impairment, but only after race completion. the incidence of renal injury during these multi-day ultramarathons is currently unknown. this is the first prospective cohort study to evaluate the incidence of acute kidney injury (aki) in runners during a multi-day ultramarathon foot race. objectives: to assess the effect of inter-stage recovery versus cumulative damage on resulting renal function during a multi-day ultramarathon. methods: demographic and biochemical data gathered via phlebotomy and analyzed by istatÒ (abbott, nj) were collected at the start and finish of day ( miles), ( miles), and ( miles) during racing the planet'sÒ -mile, -day self-supported desert ultramarathons. pre-established rifle criteria using creatinine (cr) and glomerular filtration rate (gfr) defined aki as ''no injury'' (cr < . x normal, decrease of gfr < %), ''risk'' (cr . x normal, decrease of gfr by - %), and ''injury'' (cr x normal, decrease of gfr by - %). results: thirty racers ( % male) with a mean (+/) sd) age of + /- years were studied during the sahara (n = , . %), gobi (n = , %), and namibia (n = , . %) events. the average decrease in gfr from day start to day finish was + /- (p < . , % ci . - . ); day start to day finish was . + /- . (p < . , % ci . - . ); and day start to day finish was . ± . (p < . , % ci . - ). runners categorized as risk and injury for aki after stage was . % and %; after stage was % and %, and after stage was . % and . % conclusion: the majority of participants developed significant levels of renal impairment despite recovery intervals. given the changes in renal function, potentially harmful non-steroidal anti-inflammatory drugs should be minimized to prevent exacerbating acute kidney injury. background: more than % of the elderly abuse prescription drugs, and emergency medicine providers frequently struggle to identify features of opioid addiction in this population. the prescription drug use questionnaire (pduqp) is a validated, -item, patient-administered tool developed to help health care providers better identify problematic opioid use, or dependence, in patients who receive opioids for the treatment of chronic pain. objectives: to identify the prevalence of prescription drug misuse features in elderly ed patients. methods: this cross-sectional, observational study was conducted between / and / in the ed of an urban, university-affiliated community hospi-tal that serves a large geriatric population. all patients aged to inclusive were eligible, and were recruited on a convenience basis. exclusion criteria included known dementia, and critical illness. outcomes of interest included self-reported history of prior prescription opioid use, substance abuse history, aberrant medication-taking behaviors, and pduqp results. results: one hundred patients were approached for participation. two were excluded for inability to read english, three were receiving analgesia for metastatic cancer, had never taken a prescription opioid, and seven refused to participate beyond pre-screening. sixty patients completed the study (see table ). of those, . % reported four or more visits within months; chronic pain was reported by . %; debilitating pain by . %; prior pain management referral by . %; and storing opioids for future use by %. seventeen patients reported current prescription opioid use, and were administered the pduqp (see figure) . in this population, . % thought their pain was not adequately being treated; . % reported having to increase the amount of pain medication they were taking over the prior months; . % saved up future pain medication; . % had doctors refuse to give them pain medication for fear that the patient would abuse the prescription opioids; and . % reported having a previous drug or alcohol problem. conclusion: screening instruments, such as the pduqp, facilitate identification of geriatric patients with features of opioid misuse. a high proportion of patients in this study save opioids for further use. interventions for safe medication disposal may decrease access to opioids and subsequent morbidity. age extremes, male sex, and several chronic health conditions were associated with increased odds of heat stroke, hospital admission, and death in the ed by a factor of - . chronic hematologic disease (e.g. anemia) was associated with a - fold increase in adjusted odds of each of these outcomes. conclusion: hri imposes a substantial public health burden, and a wider range of chronic conditions confer susceptibility than previously thought. males, older adults, and patients with chronic conditions, particularly anemia, are likely to have more severe hri, be admitted, or die in the ed. background: carbon monoxide (co) poisoning is a remarkable cause of death worldwide. co, produced by the incomplete combustion of hydrocarbons, has many toxic effects on especially the heart and brain. co binds strongly to cytochrome oxidase, hemoglobin, and myoglobin causing hypoxia of organs and issues. co converts hemoglobin to carboxyhemoglobin and makes transport of oxygen through the body impossible and causes severe hypoxia. objectives: the aim of this study is to investigate the levels of s b and neuron specific enolase (nse) measured both during admittance and at the sixth hour of hyperbaric and normobaric oxygen therapy carried out on patients with a diagnosis of co poisoning. methods: the study is designed as a prospective observational laboratory study. forty patients were enrolled in the study: underwent normobaric oxygen therapy (nbot) and the other underwent hyperbaric oxygen therapy (hbot). levels of s b and nse were measured both during admittance and at the sixth hour of admittance of all patients. demographic data, clinical characteristics, and outcome measures were recorded. all data were statistically analyzed. results: in both treatment groups, mean levels of nse after therapy were significantly lower than admittance levels. although levels of nse measured before and hours after treatment in hbot group were high, the difference between groups was not statistically significant (p > . ). in both treatment groups, mean levels of s b after therapy were significantly lower than admittance levels; likewise nse. although levels of s b measured before and hours after treatment in hbot group were high, the difference between groups was not statistically significant (p > . ). additionally, while levels of s b measured after treatment in the hbot group were lower compared to the nbot group, the difference between groups was also not statistically significant (p > . ). conclusion: levels of s b and nse as evidence for brain injury elevation in case of co poisoining and decrease by therapy according to our study as well as previous studies. decrease in levels of s b is more significant. according to our results, s b and nse may be useful markers in case of co poisoning; however, we did not meet any data providing more value in determining hbot indications and determining levels of cohb in the management of patients with a diagnosis of co poisoining. neurons objectives: this study was conducted to determine if neurons in the dmh, and its neighbor the paraventricular hypothalamus (pvn), were likewise involved in mdma-mediated neuroendocrine responses, and if serotonin a receptors ( -ht a) play a role in this regional response. methods: in both experiments, male sprague dawley rats (n = - /group) were implanted with bilateral cannulas targeting specific regions of the brain, i.v. catheters for drug delivery, and i.a. catheters for blood withdrawal. experiments were conducted in raturn cages, which allow blood withdrawal and drug administration in free moving animals while recording their locomotion. in the first experiment, rats were microinjected into the dmh, the pvn, or a region between, with the gabaa agonist muscimol ( pmol/ nl/side) or pbs ( nl) and min later were injected with either mdma ( . mg/kg i.v.) or an equal volume of saline. blood was withdrawn prior to microinjections and minutes after mdma for ria measurement of plasma acth. locomotion was recorded throughout the experiment. in a separate experiment of identical design, either the -ht a antagonist way (way, nmol/ nl/side) or saline was microinjected followed by i.v. injection of mdma or saline. in both experiments, increases in acth and distance traveled were compared between groups using an anova analysis. results: when compared to controls, microinjections of muscimol into the dmh, pvn, or the area in between attenuated plasma increases in acth and locomotion evoked by mdma. when microinjected into the dmh or pvn, way had no effect on acth, but when injected into the region of the dmh it significantly increased locomotion. background: poor hand-offs between physicians when admitting patients have been shown to be a major source of medical errors. objectives: we propose that training in a standardized admissions protocol by emergency medicine (em) to internal medicine (im) residents would improve the quality of and quantity of communication of vital patient information. methods: em and im residents at a large academic center developed an evidence-based admission handover protocol termed the ' ps' (table ) . em and im residents received ' ps' protocol training. im residents recorded prospectively how well each of the seven ps were communicated during each admission pre-and post-intervention. im residents also assessed the overall quality of the handover using a likert scale. the primary outcome was the change in the number of 'ps' conveyed by the em resident to the accepting im resident. data were collected for six weeks before and then for six weeks starting two weeks after the educational intervention. results: there were observations recorded in the preintervention (control) group and observations in the post-intervention group. for each of the seven 'ps' the percentage of observation where all of the information was communicated is shown in table . the communication of 'ps' increased following the intervention. this rise was statistically significant for patient information and pending tests. in the control group the mean of total communicated ps was and in the intervention group, the mean increased to (p < . ). the quality of the handover communication had a mean rating of . in the control group and . in the intervention group (p < . ). conclusion: this educational intervention in a cohort of em and im residents improved the quality and quantity of vital information communicated during patient handovers. the intervention was statistically significant for patient information transfer and tests pending. the results are limited by study size. based on our preliminary data, an agreed-upon handover protocol with training improved the amount and quality of communication during patients' hospital admission on simple items that were likely had been taken for granted as routinely transmitted. we recruited a convenience sample of residents and students rotating in the pediatric emergency department. a two-sided form had the same seven clinical decisions on each side: whether to perform blood, urine, spinal fluid tests, imaging, iv fluids, antibiotics, or a consult. the rating choices were: definitely not, probably not, probably would, and definitely would. trainees rated each decision after seeing a patient, but before presenting to the preceptor, who, after evaluating the patient, rated the same seven decisions on the second side of the form. the preceptor also indicated the most relevant decision (mrd) for that patient. we examined the validity of the technique using hypothesis testing; we posited that residents would have a higher degree of concordance with the preceptor than would medical students. this was tested using dichotomized analyses (accuracy, kappa) and roc curves with the preceptor decision as the gold standard. results: thirty-one students completed forms (median forms; iqr , ) and residents completed ( ; iqr , ). preceptors included attending physicians and fellows ( ; iqr , ). students were concordant with preceptors in % (k = . ) of mrd while residents agreed in . % (p = . ), k = . . roc analysis revealed significant differences between students and residents in the auc for the mrd ( . vs . ; p = . ). conclusion: this measure of trainee-preceptor concordance requires further research but may eventually allow for assessment of trainee clinical decision-making. it also has the pedagogical advantage of promoting independent trainee decision-making. background: basic life support (bls) and advanced cardiac life support (acls) are integral parts of emergency cardiac care. this training is usually reserved in most institutions for residents and faculty. the argument can be made to introduce bls and acls training earlier in the medical student curriculum to enhance acquisition of these skills. objectives: the goal of the survey was to characterize the perceptions and needs of graduating medical students in regards to bls and acls training. methods: this was a survey-based study of graduating fourth year medical students at a u.s. medical school. the students were surveyed before voluntarily participating in a student-led acls course in march of their final year. the surveys were distributed before starting the training course. both bls and acls training, comfort levels, and perceptions were assessed in the survey. results: of the students in the graduating class, participated in the training class with ( %) completing the survey. % of students entered medical school without any prior training and % started clinics without training. . % of students reported witnessing an average of . in-hospital cardiac arrests during training (range of - ). overall, students rated their preparedness . (sd . ) for adult resuscitations on a - likert scale with being the unprepared. % and % of students believe that bls and acls should be included in the medical student curriculum respectively with a preference for teaching before starting clerkships. % of students avoided participating in resuscitations due to lack of training. of those, % said they would have participated had they been trained. conclusion: to our knowledge, this is one of the first studies to address the perceptions and needs for bls and acls training in u.s. medical schools. students feel that bls and acls training is needed in their curriculum and would possibly enhance perceived comfort levels and willingness to participate in resuscitations. background: professionalism is one of six core competency requirements of the acgme, yet defining and teaching its principles remains a challenge. the ''social contract'' between physician and community is clearly central to professionalism so determining the patient's understanding of the physician's role in the relationship is important. because specialization has created more narrowly focused and often quite different interactions in different medical environments, the patient concept of professionalism in different settings may vary as well. objectives: we hoped to determine if patients have different conceptions of professionalism when considering physicians in different clinical environments. methods: patients were surveyed in the waiting room of an emergency department, an outpatient internal medicine clinic, and a pre-operative/anesthesia clinic. the survey contained examples of attributes, derived from the american board of internal medicine's eight characteristics of professionalism. participants were asked to rate, on a -point scale, the importance that a physician possess each attribute. an anova analysis was used to compare the sites for each question. results: of who took the survey, were in the emergency department, were in the medicine clinic, and were in the pre-operative clinic. females comprised % of the study group and the average age was with a range from to . there was a significant difference on the attribute of ''providing a portion of work for those who cannot pay;'' this was rated higher in the emergency department (p = . ). there was near-significance (p = . ) on the attribute of ''being able to make difficult decisions under pressure,'' which was rated higher in the pre-op clinic. there was no difference for any of the other questions. the top four professional attributes at each clinical site were the same -''honesty,'' ''excellence in communication and listening,'' ''taking full responsibility for mistakes,'' and ''technical competence/ skill;'' the bottom two were ''being an active leader in the community'' and ''patient concerns should come before a doctor's family commitments.'' conclusion: very few differences between clinical sites were found when surveying patient perception of the important elements of medical professionalism. this may suggests a core set of values desired by patients for physicians across specialties. emergency medicine faculty knowledge of and confidence in giving feedback on the acgme core competencies todd guth, jeff druck, jason hoppe, britney anderson university of colorado, aurora, co background: the acgme mandates that residency programs assess residents based upon six core competencies. although the core competencies have been in place for a number of years, many faculty are not familiar with the intricacies of the competencies and have difficulty giving competency-specific feedback to residents. objectives: the purpose of the study is to determine the extent to which emergency medicine (em) faculty can identify the acgme core competencies correctly and to determine faculty confidence with giving general feedback and core competency focused feedback to em residents. methods: design and participants: at a single department of em, a survey of twenty-eight faculty members, their knowledge of the acgme core competencies, and their confidence in providing feedback to residents was conducted. confidence levels in giving feedback were scored on a likert scale from to . observations: descriptive statistics of faculty confidence in giving feedback, identification of professional areas of interest, and identification of the acgme core competencies were determined. mann-whitney u tests were used to make comparisons between groups of faculty given the small sample size of the respondents. results: there was a % response rate of the faculty members surveyed. eight faculty members identified themselves as primarily focused on education. although those faculty members identifying themselves as focused on education scored higher than non-education focused faculty for all type of feedback (general feedback, constructive feedback, negative feedback), there was only a statistical difference in confidence levels . versus . (p < . ) for acgme core competency specific feedback when compared to noneducation focused faculty. while education focused faculty correctly identified all six of acgme core competencies % of the time, not one of the non-education focused faculty identified all six of the core competencies correctly. non-education focused faculty only correctly identified three or more competencies % of the time. conclusion: if residency programs are to assess residents using the six acgme core competencies, additional faculty development specific to the core competencies will be needed to train all faculty on the core competencies and on how to give core competency specific feedback to em residents. there is no clear consensus as to the most effective tool to measure resident competency in emergency ultrasound. objectives: to determine the relationship between the number of scans and scores on image recognition, image acquisition, and cognitive skills as measured by an objective structured clinical exam (osce) and written exam. secondarily, to determine whether image acquisition, image recognition, and cognitive knowledge require separate evaluation methodologies. methods: this was a prospective observational study in an urban level i ed with a -year acgme-accredited residency program. all residents underwent an ultrasound introductory course and a one-month ultrasound rotation during their first and second years. each resident received a written exam and osce to assess psychomotor and cognitive skills. the osce had two components: ( ) recognition of images, and ( ) acquisition of images. a registered diagnostic medical sonographer (rdms)-certified physician observed each bedside examination. a pre-existing residency ultrasound database was used to collect data about number of scans. pearson correlation coefficients were calculated for number of scans, written exam score, image recognition, and image acquisition scores on the osce. results: twenty-nine residents were enrolled from march to february who performed an average of scans (range - ). there was no significant correlation between number of scans and written exam scores. an analysis of the number of scans and the ocse found a moderate correlation with image acquisition (r = . , p = . ) and image recognition (r = . , p = < . )). pearson correlation analysis between the image acquisition score and image recognition score found that there was no correlation (r = . , p = . ). there was a moderate correlation with image acquisition scores to written scores (r = . , p = . ) and image recognition scores to written scores (r = . , p = . ). conclusion: the number of scans does not correlate with written tests but has a moderate correlation with image acquisition and image recognition. this suggests that resident education should include cognitive instruction in addition to scan numbers. we conclude that multiple methods are necessary to examine resident ultrasound competency. background: although emergency physicians must often make rapid decisions that incorporate their interpretation of an ecg, there is no evidence-based description of ecg interpretation competencies for emergency medicine (em) trainees. the first step in defining these competencies is to develop a prioritized list of ecg findings relevant to em contexts. objectives: the purpose of this study was to categorize the importance of various ecg diagnoses and/or findings for the em trainee. methods: we developed an extensive list of potentially important ecg diagnoses identified through a detailed review of the cardiology and em literature. we then conducted a three-round delphi expert opinion-soliciting process where participants used a five-point likert scale to rate the importance of each diagnosis for em trainees. consensus was defined as a minimum of percent agreement on any particular diagnosis at the second round or later. in the absence of consensus, stability was defined as a shift of percent or less after successive rounds. results: twenty-two em experts participated in the delphi process, sixteen ( %) of whom completed the process. of those, fifteen were experts from eleven different em training programs across canada and one was a recognized expert in em electrocardiography. overall, diagnoses reached consensus, achieved stability, and one diagnosis achieved neither consensus nor stability. out of potentially important ecg diagnoses, ( %) were considered ''must know'' diagnoses, ( %) ''should know'' diagnoses, and ( %) ''nice to know'' diagnoses. conclusion: we have categorized ecg diagnoses within an em training context, knowledge of which may allow clinical em teachers to establish educational priorities. this categorization will also facilitate the development of an educational framework to establish em trainee competency in ecg interpretation. ''rolling refreshers background: cardiac arrest survival rates are low despite advances in cardiopulmonary resuscitation. high quality cpr has been shown to impart greater cardiac arrest survival; however, retention of basic cpr skills by health care providers has been shown to be poor. objectives: to evaluate practitioner acceptance of an in-service cpr skills refresher program, and to assess for operator response to real-time feedback during refreshers. methods: we prospectively evaluated a ''rolling refresher'' in-service program at an academic medical center. this program is a proctored cpr practice session using a mannequin and cpr-sensing defibrillator that provides real-time cpr quality feedback. subjects were basic life support-trained providers who were engaged in clinical care at the time of enrollment. subjects were asked to perform two minutes of chest compressions (ccs) using the feedback system. ccs could be terminated when the subject had completed approximately seconds of compressions with < corrective prompts. a survey was then completed by to obtain feedback regarding the perceived efficacy of this training model. cpr quality was then evaluated using custom analysis software to determine the percent of cc adequacy in -second intervals. results: enrollment included subjects from the emergency department and critical care units ( nurses, physicians, students and allied health professionals). all participants completed a survey and cpr performance data logs were obtained. positive impressions of the in-service program were registered by % ( / ) and % ( / ) reported a self-perceived improvement in skills confidence. eighty-three percent ( / ) of respondents felt comfortable performing this refresher during a clinical shift. thirtynine percent ( / ) of episodes exhibited adequate cc performance with approximately seconds of cc. of the remaining episodes, . ± . % of cc were adequate in the first seconds with . ± . % of cc adequate during the last second interval (p = . ). of these individuals, improved or had no change in their cpr skills, and individuals skills declined during cc performance (p = . ). conclusion: implementation of a bedside cpr skill refresher program is feasible and is well received by hospital staff. real time cpr feedback improved upon cpr skill performance during the in-service session. teaching emergency medicine skills: is a self-directed, independent, online curriculum the way of the future? tighe crombie, jason r. frank, stephen noseworthy, richard gerein, a. curtis lee university of ottawa, ottawa, on, canada background: procedural competence is critical to emergency medicine, but the ideal instructional method to acquire these skills is not clear. previous studies have demonstrated that online tutorials have the potential to be as effective as didactic sessions at teaching specific procedural skills. objectives: we studied whether a novel online curriculum teaching pediatric intraosseus (io) line insertion to novice learners is as effective as a traditional classroom curriculum in imparting procedural competence. methods: we conducted a randomized controlled educational trial of two methods of teaching io skills. preclinical medical students with no past io experience completed a written test and were randomized to either an online or classroom curriculum. the online group (og) were given password-protected access to a website and instructed to spend minutes with the material while the didactic group (dg) attended a lecture of similar duration. participants then attended a -minute unsupervised manikin practice session on a separate day without any further instruction. a videotaped objective structured clinical examination (osce) and post-course written test were completed immediately following this practice session. finally, participants were crossed over into the alternate curriculum and were asked to complete a satisfaction survey that compared the two curricula. results were compared with a paired t-test for written scores and an independent t-test for osce scores. results: sixteen students completed the study. pre-course test scores of the two groups were not significantly different prior to accessing their respective curricula (mean scores of % for og and % for dg, respectively; p > . ). post-course written scores were also not significantly different (both with means of %; p > . ); however, for the post-treatment osce scores, the og group scored significantly higher than the dg group (mean scores of . % and . %; t( ) = . , p < . .) conclusion: this novel online curriculum was superior to a traditional didactic approach to teaching pediatric io line insertion. novice learners assigned to a selfdirected online curriculum were able to perform an emergency procedural skill to a high level of performance. em educators should consider adopting online teaching of procedural skills. background: applicants to em residency programs obtain information largely from the internet. curricular information is available from a program's website (pw) or the saem residency directory (sd). we hypothesize that there is variation between these key sources. objectives: to identify discrepancies between each pw and sd. to describe components of pgy - em residency programs' curricula as advertised on the internet. methods: pgy - residencies were identified through the sd. data were abstracted from individual sd and pw pages identifying pre-determined elements of interest regarding rotations in icu, pediatrics, inpatient (medicine, pediatrics, general surgery), electives, orthopedics, toxicology, and anesthesia. agreement between the sd and pw was calculated using a cohen's unweighted kappa calculation. curricula posted on pws were considered the gold standard for the programs' current curricula. results: a total of pgy - programs were identified through the sd and confirmed on the pw. ninetyone of programs ( %) had complete curricular information on both sites. only these programs were included in the kappa analysis for sd and pw comparisons. of programs with complete listings, of programs ( %) had at least one discrepancy. the agreement of information between pw and sd revealed a kappa value of . ( % ci . - . ). analysis of pw revealed that pgy - programs have an average of . (range, - ), . (range, - ), . (range, - ), and . (range, - ) blocks of icu, pediatrics, elective, and inpatient, respectively. common but not rrc-mandated rotations in orthopedics, toxicology, and anesthesiology are present in , , and percent of programs, respectively. conclusion: publicly accessible curricular information through the sd and pw for pgy - em programs only has fair agreement (using commonly accepted kappa value guides). applicants may be confused by the variability of data and draw inaccurate conclusions about program curricula. from the gravid uterus and improves cardiac output; however, this theory has never been proven. objectives: we set out to determine the difference in inferior vena cava (ivc) filling when third trimester patients were placed in supine, llt, and right lateral tilt (rlt) positions using ivc ultrasound. methods: healthy pregnant women in their third trimester presenting to the labor and delivery suite were enrolled. patients were placed in three different positions (supine, rlt, and llt) and ivc maximum (max) and minimum (min) measurements were obtained using the intercostal window in short axis approximately two centimeters below the entry of the hepatic veins. ivc collapse index (ci) was calculated for each measurement using the formula (max-min)/max. in addition, blood pressure, heart rate, and fetal heart rate were monitored. patients stayed in each position for at least minutes prior to taking measurements. we compared ivc measurements using a one-way analysis of variance for repeated measures. results: twenty patients were enrolled. the average age was years (sd . ) with a mean estimated gestational age of . weeks (sd . ). there were no significant differences seen in ivc filling in each of the positions (see table ). in addition, there were no differences in hemodynamic parameters between positions.ten ( %) patients had the largest ivc measurement in the llt position, ( %) patients in the rlt position, and ( %) in the supine position. conclusion: there were no significant differences in ivc filling between patient positions. for some third trimester patients llt may not be the optimal position for ivc filling. background: although the acgme and rrc require competency assessment in ed bedside ultrasound (us), there are no standardized assessment tools for us training in em. objectives: using published us guidelines, we developed four observed structured competency evalua-tions (osce) for four common em us exams: fast, aortic, cardiac, and pelvic. inter-rater reliability was calculated for overall performance and for the individual components of each osce. methods: this prospective observational study derived four osces that evaluated overall study competency, image quality for each required view, technical factors (probe placement, orientation, angle, gain, and depth), and identification of key anatomic structures. em residents with varying levels of training completed an osce under direct observation of two em-trained us experts. each expert was blinded to the other's assessment. overall study competency and image quality of each required views were rated on a five-point scale ( poor, -fair, -adequate, -good, -excellent), with explicit definitions for each rating. each study had technical factors (correct/incorrect) and anatomic structures (identified/not identified) assessed as binary variables. data were analyzed using cohen's and weighted k, descriptive statistics, and % ci. results: a total of us exams were observed, including fast, cardiac, aorta, and pelvic. total assessments included ratings of overall study competency, ratings of required view image quality, ratings of technical factors, and ratings of anatomic structures. inter-rater assessment of overall study competency showed excellent agreement, raw agreement . ( . , . ), weighted k . ( . , . ). ratings of required view image quality showed excellent agreement: raw agreement . ( . , . ), weighted k . ( . , . ). inter-rater assessment of technical factors showed substantial agreement: raw agreement . ( . , . ), cohen's k . ( . , . ). ratings of identification of anatomic structures showed substantial agreement: raw agreement . ( . , . ), cohen's k . ( . , . ). conclusion: inter-rater reliability is substantial to excellent using the derived ultrasound osces to rate em resident competency in fast, aortic, cardiac, and pelvic ultrasound. validation of this tool is ongoing. a objectives: the objective of this study was to identify which transducer orientation, longitudinal or transverse, is the best method of imaging the axillary vein with ultrasound, as defined by successful placement in the vein with one needle stick, no redirections, and no complications. methods: emergency medicine resident and attending physicians at an academic medical center were asked to cannulate the axillary vein in a torso phantom model. the participants were randomized to start with either the longitudinal or transverse approach and completed both sequentially, after viewing a teaching presentation. participants completed pre-and post-attempt questionnaires. measurements of each attempt were taken regarding time to completion, success, skin punctures, needle redirections, and complications. we compared proportions using a normal binomial approximation and continuous data using the t-distribution, as appropriate. a sample size of was chosen based on the following assumptions: power, . ; significance, . ; effect size, % versus %. results: fifty-seven operators with a median experience of prior ultrasounds ( to iqr) participated. first-attempt success frequency was / ( . ) for the longitudinal method and / ( . ) for the transverse method (difference . , % ci . - . ); this difference was similar regardless of operator experience. the longitudinal method had fewer redirections (mean difference . , % ci . - . ) and skin punctures (mean difference . , % ci ) to . ). arterial puncture occurred in / longitudinal attempts and / transverse attempts, with no pleural punctures in either group. among successful attempts, the time spent was seconds less for longitudinal method ( % ci - ). though % of participants had more experience with the transverse method prior to the training session, % indicated after the session that they preferred the longitudinal method. methods: a prospective single-center study was conducted to assess the compressibility of the basilic vein with ultrasound. healthy study participants were recruited. the compressibility was assessed at baseline, and then further assessed with one proximal tourniquet, two tourniquets (one distal and one proximal), and a proximal blood pressure cuff inflated to mmhg. compressibility was defined as the vessel's resistance to collapse to external pressure and rated as completely compressible, moderately compressible, or mildly compressible after mild pressure was applied with the ultrasound probe. results: one-hundred patients were recruited into the study. ninety-eight subjects were found to have a completely compressible basilic vein at baseline. when one tourniquet and two tourniquets were applied and participants, respectively, continued to have completely compressible veins. a fisher's exact test comparing one versus two tourniquets revealed no difference between these two techniques (p = . ). only two participants continued to have completely compressible veins following application of the blood pressure cuff. the compressibility of this group was found to be statistically significant by fisher's exact test compared to both tourniquet groups (p < . ). furthermore, participants with the blood pressure cuff applied were found to have moderately compressible veins and participants were found to have mildly compressible veins. conclusion: tourniquets and blood pressure cuffs can both decrease the compressibility of peripheral veins. while there was no difference identified between using one and two tourniquets, utilization of a blood pressure cuff was significantly more effective to decrease compressibility. the findings of this study may be utilized in the emergency department when attempting to obtain peripheral venous access, specifically supporting the use of blood pressure cuffs to decrease compressibility. background: electroencephalography (eeg) is an underused test that can provide valuable information in the evaluation of emergency department (ed) patients with altered mental status (ams). in ams patients with nonconvulsive seizure (ncs), eeg is necessary to make the diagnosis and to initiate proper treatment. yet, most cases of ncs are diagnosed > h after ed presentation. obstacles to routine use of eeg in the ed include space limitations, absence of / availability of eeg technologists and interpreters, and the electrically hostile ed environment. a novel miniature portable wireless device (microeeg) is designed to overcome these obstacles. objectives: to examine the diagnostic utility of micro-eeg in identifying eeg abnormalities in ed patients with ams. methods: an ongoing prospective study conducted at two academic urban eds. inclusion: patients ‡ years old with ams. exclusion: an easily correctable cause of ams (e.g. hypoglycemia, opioid overdose). three -minute eegs were obtained in random order from each subject beginning within one hour of presentation: ) a standard eeg, ) a microeeg obtained simultaneously with conventional cup electrodes using a signal splitter, and ) a microeeg using an electrocap. outcome: operative characteristics of micro-eeg in identifying any eeg abnormality. all eegs were interpreted in a blinded fashion by two board-certified epileptologists. within each reader-patient pairing, the accuracy of eegs and were each assessed relative to eeg . sensitivity, specificity, and likelihood ratios (lr) are reported for microeeg by standard electrodes and electrocap (eegs and ). inter-rater variability for eeg interpretations is reported with kappa. results: the interim analysis was performed on consecutive patients (target sample size: ) enrolled from may to october (median age: , range: - , % male). overall, % ( % confidence interval [ci], - %) of interpretations were abnormal (based on eeg ). kappa values representing the agreement of neurologists in interpretation of eeg - were . ( . - . ), . ( . - . ), and . ( . - . ), respectively. conclusion: the diagnostic accuracy and concordance of microeeg are comparable to those of standard eeg but the unique ed-friendly characteristics of the device could help overcome the existing barriers for more frequent use of eeg in the ed. (originally submitted as a ''late-breaker.'') a background: patients who use an ed for acute migraine are characterized by higher migraine disability scores, lower socio-economic status, and are unlikely to have used a migraine-specific medication prior to ed presentation. objectives: to determine if a comprehensive migraine intervention, delivered just prior to ed discharge, could improve migraine impact scores one month after the ed visit. methods: this was a randomized controlled trial of a comprehensive migraine intervention versus typical care among patients who presented to an ed for management of acute migraine. at the time of discharge, for patients randomized to comprehensive care, we reinforced their diagnosis, shared a migraine education presentation from the national library of medicine, provided them with six tablets of sumatriptan mg and tablets of naproxen mg, and if they wished, provided them with an expedited free appointment to our institution's headache clinic. patients randomized to typical care received the care their attending emergency physician felt was appropriate. the primary outcome was a between-group comparison of the hit score, a validated headache assessment instrument, one month after ed discharge. secondary outcomes included an assessment of satisfaction with headache care and frequency of use of migraine-specific medication within that one month period. the outcome assessor was blinded to assignment. results: over a month period, migraine patients were enrolled. one month follow-up was successfully obtained in % of patients. baseline characteristics were comparable. one month hit scores in the two groups were nearly identical ( vs , %ci for difference of : ) , ), as was dissatisfaction with overall headache care ( % versus %, %ci for difference of %: ) , %). not surprisingly, patients randomized to the comprehensive intervention were more likely to be using triptans or migraine-preventive therapy ( % versus %, %ci for difference of %: , %) one month later. conclusion: a comprehensive migraine intervention, when compared to typical care, did not improve hit scores one month after ed discharge. future work is needed to define a migraine intervention that is practical and useful in an ed. background: lumbar puncture (lp) is the standard of care for excluding non-traumatic subarachnoid hemorrhage (sah), and is usually performed following head ct (hct). however, in the setting of a non-diagnostic hct, lp demonstrates a low overall diagnostic yield for sah (< % positive rate). objectives: to describe a series of ed patients diagnosed with sah by lp following a non-diagnostic hct, and, when compared to a set of matched controls, determine if clinical variables can reliably identify these ''ct-negative/lp-positive'' patients. methods: retrospective case-control chart review of ed patients in an integrated health system between the years - (estimated - million visits among eds). patients with a final diagnosis of non-traumatic sah were screened for case inclusion, defined as an initial hct without sah by final radiologist interpretation and a lp with > red blood cells/mm , along with either ) xanthochromic cerebrospinal fluid, ) angiographic evidence of cerebral aneurysm or arteriovenous malformation, or ) head imaging showing sah within hours following lp. control patients were randomly selected among ed patients diagnosed with headache following a negative sah evaluation with hct and lp. controls were matched to cases by year and presenting ed in a : ratio. stepwise logistic regression and classification and regression tree analysis (cart) were employed to identify predictive variables. inter-rater reliability (kappa) was determined by independent chart review. results: fifty-five cases were identified. all cases were hunt-hess grade or . demographics are shown in table . thirty-four cases ( %) had angiographic evidence of sah. five variables were identified that positively predicted sah following a normal hct with % sensitivity ( % ci, - %) and % specificity ( % ci, - %): age > years, neck pain or stiffness, onset of headache with exertion, vomiting with headache, or loss of consciousness at headache onset. kappa values for selected variables ranged from . - . ( % sample). the c-statistic (auc) and hosmer-lemeshow test p-value for the logistic regression model are . and . , respectively (table ) . conclusion: several clinical variables can help safely limit the amount of invasive testing for sah following a non-diagnostic hct. prospective validation of this model is needed prior to practice implementation. background: post-thrombolysis intracerebral hemorrhage (ich) is associated with poor outcomes. previous investigations have attempted to determine the relationship between pre-existing anti-platelet (ap) use and the safety of intravenous thrombolysis, but have been limited by low event rates thus decreasing the precision of estimates. objectives: our objective was to determine whether pre-existing ap therapy increases the risk of ich following thrombolysis. methods: consecutive cases of ed-treated thrombolysis patients were identified using multiple methods, including active and passive surveillance. retrospective data were collected from four hospitals from - , and distinct hospitals from - as part of a cluster randomized trial. the same chart abstraction tool was used during both time periods and data were subjected to numerous quality control checks. hemorrhages were classified using a pre-specified methodology: ich was defined as presence of hemorrhage in radiographic interpretations of follow up imaging (primary outcome). symptomatic ich (secondary outcome) was defined as radiographic ich with associated clinical worsening. a multivariable logistic regression model was constructed to adjust for clinical factors previously identified to be related to postthrombolysis ich. as there were fewer sich events, the multivariable model was constructed similarly, except that variables divided into quartiles in the primary analysis were dichotomized at the median. results: there were patients included, with % having documented pre-existing ap treatment. the mean age was years, the cohort was % male, and the median nihss was . the unadjusted proportion of patients with any ich was . % without ap and . % with ap (difference . %, % ci ) . % to . %); for sich this was . % without ap and % with ap (difference . %, %ci ) to . %). no significant association between pre-existing ap treatment with radiographic or symptomatic ich was observed (table) . conclusion: we did not find that ap treatment was associated with post-thrombolysis ich or sich in this cohort of community treated patients. pre-existing tobacco use, younger age, and lower severity were associated with lower odds of sich. an association between ap therapy and sich may still exist -further research with larger sample sizes is warranted in order to detect smaller effect sizes. background: post-cardiac arrest therapeutic hypothermia (th) improves survival and neurologic outcome after cardiac arrest, but the parameters required for optimal neuroprotection remain uncertain. our laboratory recently reported that -hour th was superior to -hour th in protecting hippocampal ca pyramidal neurons after asphyxial cardiac arrest in rats. cerebellar purkinje cells are also highly sensitive to ischemic injury caused by cardiac arrest, but the effect of th on this neuron population has not been previously studied. objectives: we examined the effect of post-cardiac arrest th onset time and duration on purkinje neuron survival in cerebella collected during our previous study. methods: adult male long evans rats were subjected to -minute asphyxial cardiac arrest followed by cpr. rats that achieved return of spontaneous circulation (rosc) were block randomized to normothermia ( . deg c) or th ( . deg c) initiated , , , or hours after rosc and maintained for or hours (n = per group). sham injured rats underwent anesthesia and instrumentation only. seven days post-cardiac arrest or sham injury, rats were euthanized and brain tissue was processed for histology. surviving purkinje cells with normal morphology were quantified in the primary fissure in nissl stained sagittal sections of the cerebellar vermis. purkinje cell density was calculated for each rat, and group means were compared by anova with bonferroni analysis. results: purkinje cell density averaged (+/) sd) . ( . ) cells/mm in sham-injured rats. neuronal survival in normothermic post-cardiac arrest rats was significantly reduced compared to sham ( . % ( . %)). overall, th resulted in significant neuroprotection compared to normothermia ( . % ( . %) of sham). purkinje cell density with -hour duration th was . % ( . %) of sham and -hour duration th was . % ( . %), both significantly improved from sham (p = . between durations). th initiated , , , and hours post-rosc provided similar benefit: . % ( . %), . % ( . %), . % ( . %), and . % ( . %) of sham, respectively. conclusion: overall, these results indicate that postcardiac arrest th protects cerebellar purkinje cells with a broad therapeutic window. our results underscore the importance of considering multiple brain regions when optimizing the neuroprotective effect of post-cardiac arrest th. the effect of compressor-administered defibrillation on peri-shock pauses in a simulated cardiac arrest scenario joshua glick, evan leibner, thomas terndrup penn state hershey medical center, hershey, pa background: longer pauses in chest compressions during cardiac arrest are associated with a decreased probability of successful defibrillation and patient survival. having multiple personnel share the tasks of performing chest compressions and shock delivery can lead to communication complications that may prolong time spent off the chest. objectives: the purpose of this study was to determine whether compressor-administered defibrillation led to a decrease in pre-shock and peri-shock pauses as compared to bystander-administered defibrillation in a simulated in-hospital cardiac arrest scenario. we hypothesized that combining the responsibilities of shock delivery and chest-compression performance may lower no-flow periods. methods: this was a randomized, controlled study measuring pauses in chest compressions for defibrillation in a simulated cardiac arrest. medical students and ed personnel with current cpr certification were surveyed for participation between july and october . participants were randomized to either a control (facilitator-administered shock) or variable (participantadministered shock) group. all participants completed one minute of chest compressions on a mannequin in a shockable rhythm prior to initiation of prompt and safe defibrillation. pauses for defibrillation were measured and compared in both study groups. results: out of total enrollments, the data from defibrillations were analyzed. subject-initiated defibrillation resulted in a significantly lower pre-shock handsoff time ( . s; % ci: . - . ) compared to facilitator-initiated defibrillation ( . s; % ci: . - . ). furthermore, subject-initiated defibrillation resulted in a significantly lower peri-shock hands-off time ( . s; % ci: . - . ) compared to facilitator-initiated defibrillation ( . s; % ci: . - . ). conclusion: assigning the responsibility for shock delivery to the provider performing compressions encourages continuous compressions throughout the charging period and decreases total time spent off the chest. this modification may also decrease the risk of accidental shock and improve patient survival. however, as this was a simulation-based study, clinical implementation is necessary to further evaluate these potential benefits. objectives: to determine the sensitivity and specificity of peripheral venous oxygen (po ) to predict abnormal central venous oxygen saturation in septic shock patients in the ed. methods: secondary analysis of an ed-based randomized controlled trial of early sepsis resuscitation targeting three physiological variables: cvp, map, and either scvo or lactate clearance. inclusion criteria: suspected infection, two or more sirs criteria, and either systolic blood pressure < mmhg after a fluid bolus or lactate > mm. peripheral venous po was measured prior to enrollment as part of routine care, and scvo was measured as part of the protocol. we analyzed for agreement between venous po and scvo using spearman's rank. sensitivity and specificity to predict an abnormal scvo (< %) were calculated for each incremental value of po . results: a total of were analyzed. median po was mmhg (iqr , ). median initial scvo was % (iqr , ). thirty-nine patients ( %) had an initial scvo < %. spearman's rank demonstrated fair correlation between initial po and scvo (q = . ). a cutoff of venous po < was % sensitive and % specific for detecting an initial scvo < %. twenty-seven patients ( %) demonstrated an initial po of > . conclusion: in ed septic shock patients, venous po demonstrated only fair correlation with scvo , though a cutoff value of was sensitive for predicting an abnormal scvo . twenty percent of patients demonstrated an initial value above the cutoff, potentially representing a group in whom scvo measurement could be avoided. future studies aiming to decrease central line utilization could consider the use of peripheral o measurements in these patients. sessions. ninety-two percent were rns, median clinical experience was - years, and % were from an intensive care unit. provider confidence increased significantly with a single session despite the highly experienced sample (figure ). there was a trend for further increased confidence with an additional session and the increased confidence was maintained for at least - months given the normal sensitivity analysis. conclusion: high fidelity simulation significantly increases provider confidence even among experienced providers. this study was limited by its small sample size and recent changes in acls guidelines. background: recent data suggest alarming delays and deviations in major components of pediatric resuscitation during simulated scenarios by pediatric housestaff. objectives: to identify the most common errors of pediatric residents during multiple simulated pediatric resuscitation scenarios. methods: a retrospective observational study conducted in an academic tertiary care hospital. pediatric residents (pgy and pgy ) were videotaped performing a series of five pediatric resuscitation scenarios using a high-fidelity simulator (simbaby, laerdal): pulseless non-shockable arrest, pulseless shockable arrest, dysrhythmia, respiratory arrest, and shock. the primary outcome was the presence of significant errors prospectively defined using a validated scoring instrument designed to assess sequence, timing, and quality of specific actions during resuscitations based on the aha pals guidelines. residents' clinical performances were measured by a single video reviewer. the primary analysis was the proportion of errors for each critical task for each scenario. we estimated that the evaluation of each resident would provide a confidence interval less than . for the proportion of errors. results: twenty-four of residents completed the study. across all scenarios, pulse check was delayed by more than seconds in % ( %ci: %- %). for non-shockable arrest, cpr was started more than seconds after recognizing arrest in % ( %ci - %) and inappropriate defibrillation was performed in % ( %ci - %). for shockable arrest, participants failed to identify the rhythm in % ( %ci - %), cpr was not performed in % ( %ci - %), while defibrillation was delayed by more than seconds in % ( %ci - %) and not performed in one case. for shock, participants failed to ask for a dextrose check in % ( %ci - %), and it was delayed by more than seconds for all others. conclusion: the most common error across all scenarios was delay in pulse check. delays in starting cpr and inappropriate defibrillation were common errors in non-shockable arrests, while failure to identify rhythm, cpr omission, and delaying defibrillation were noted for shockable arrests. for shock, omission of rapid dextrose check was the most common error, while delaying the test when ordered was also significant. future training in pediatric resuscitation should target these errors. background: many scoring instruments have been described to measure clinical performance during resuscitation; however, the validity of these tools has yet to be proven in pediatric resuscitation. objectives: to determine the external validity of published scoring instruments to evaluate clinical performance during simulated pediatric resuscitations using pals algorithms and to determine if inter-rater reliability could be assessed. methods: this was a prospective quasi-experimental design performed in a simulation lab of a pediatric tertiary care facility. participants were residents from a single pediatric program distinct from where the instrument was originally developed. a total of pgy s and pgy s were videotaped during five simulated pediatric resuscitation scenarios. pediatric emergency physicians rated resident performances before and after a pals course using standardized scoring. each video recording was viewed and scored by two raters blinded to one another. a priori, it was determined that, for the scoring instrument to be valid, participants should improve their scores after participating in the pals course. differences in means between pre-pals and post-pals and pgy and pgy were compared using an anova test. to investigate differences in the scores of the two groups over the five scenarios, a two-factor anova was used. reliability was assessed by calculating an interclass correlation coefficient for each scenario. results: following the pals course, scores improved by . % ( . to . ), . % ( . to . ), . % () . to . ), . % ( . to ), and . % () . to . ) for the pulseless non-shockable arrest, pulseless shockable arrest, dysrhythmia, respiratory, and shock scenarios respectively. there were no differences in scores between pgy s and pgy s before and after the pals course. there was an excellent reliability for each scoring instrument with iccs varying between . and . . conclusion: the scoring instrument was able to demonstrate significant improvements in scores following a pals course for pgy and pgy pediatric residents for the pulseless non-shockable arrest, pulseless shockable, and respiratory arrest scenarios only. however, it was unable to discriminate between pgy s and pgy s both before and after the pals course for any scenarios. the scoring instrument showed excellent inter-reliability for all scenarios. a background: medical simulation is a common and frequently studied component of emergency medicine (em) residency curricula. its utility in the context of em medical student clerkships is not well defined. objectives: the objective was to measure the effect of simulation instruction on medical students' em clerkship oral exam performance. we hypothesized that students randomized to the simulation group would score higher. we predicted that simulation instruction would promote better clinical reasoning skills and knowledge expression. methods: this was a randomized observational study conducted from / to / . participants were fourth year medical students in their em clerkship. students were randomly assigned on their first day to one of two groups. the study group received simulation instruction in place of one of the lectures, while the control group was assigned to the standard curriculum. the standard clerkship curriculum includes lectures, case studies, procedure labs, and clinical shifts without simulation. at the end of the clerkship, all students participated in written and oral exams. graders were not blinded to group allocation. grades were assigned based on a pre-defined set of criteria. the final course composite score was computed based on clinical evaluations and the results of both written and oral exams. oral exam scores between the groups were compared using a two-sample t-test. we used the spearman rank correlation to measure the association between group assignment and the overall course grade. the study was approved by our institutional irb. results: sixty-one students participated in the study and were randomly assigned to one of two groups. twenty-nine ( . %) were assigned to simulation and the remaining ( . %) students were assigned to the standard curriculum. students assigned to the simulation group scored . % ( % ci . - . %) higher on the oral exam than the non-simulation group. additionally, simulation was associated with a higher final course grade (p < . ). limitations of this pilot study include lack of blinding and interexaminer variability. conclusion: simulation training as part of an em clerkship is associated with higher oral exam scores and higher overall course grade compared to the standard curriculum. the results from this pilot study are encouraging and support a larger, more rigorous study. initial approaches to common complaints are taught using a standard curriculum of lecture and small group case-based discussion. we added a simulation exercise to the traditional altered mental status (ams) curriculum with the hypothesis that this would positively affect student knowledge, attitudes, and level of clinical confidence caring for patients with ams. methods: ams simulation sessions were conducted in june and ; student participation was voluntary. the simulation exercises included two ams cases using a full-body simulator and a faculty debriefing after each case. both students who did and did not participate in the simulations completed a written post-test and a survey related to confidence in their approach to ams. results: students completed the post-test and survey. ( %) attended the simulation session. ( %) attended all three sessions. ( %) participated in the lecture and small group. ( %) did not attend any session. post-test scores were higher in students who attended the simulations versus those who did not: (iqr, - ) vs. (iqr, - ); p < . . students who attended the simulations felt more confident about assessing an ams patient ( % vs. %; p = . ), articulating a differential diagnosis ( % vs. %; p = . ), and knowing initial diagnostic tests ( % vs. %; p = . ) and initial interventions ( % vs. %; p = . ) for an ams patient. students who attended the simulations were more likely to rate the overall ams curriculum as useful ( % vs. %; p < . ). conclusion: addition of a simulation session to a standard ams curriculum had a positive effect on student performance on a knowledge-based exam and increased confidence in clinical approach. the study's major limitations were that student participation in the simulation exercise was voluntary and that effect on applied skills was not measured. future research will determine whether simulation is effective for other chief complaints and if it improves actual clinical performance. background: the acgme has defined six core competencies for residents including ''professionalism'' and ''interpersonal and communication skills.'' integral to these two competencies is empathy. prior studies suggest that self-reported empathy declines during medical training; no reported study has yet integrated simulation into the evaluation of empathy in medical training. objectives: to determine if there is a relation between level of training and empathy in patient interactions as rated during simulation. methods: this is a prospective observational study at a tertiary care center comparing participants at four different levels of training: first (ms ) and third year (ms ) medical students, incoming em interns (pgy ), and em senior residents (pgy / ). trainees participated in two simulation scenarios (ectopic pregnancy and status asthmaticus) in which they were responsible for clinical management (cm) and patient interactions (pi). this was the first simulation exposure during an established simulation curriculum for ms , ms , and pgy . two independent raters reviewed videotaped simulation scenarios using checklists of critical actions for clinical management (cm: - points) and patient interactions (pi: - points). inter-rater reliability was assessed by intra-class correlation coefficients (iccs objectives: we explored attitudes and beliefs about the handoff, using qualitative methods, from a diverse group of stakeholders within the ems community. we also characterized perceptions of barriers to high-quality handoffs and identified strategies for optimizing this process. methods: we conducted seven focus groups at three separate gatherings of ems professionals (one local, two national) in / . snowball sampling was used to recruit participants with diverse professional, experiential, geographic, and demographic characteristics. focus groups, lasting - minutes, were moderated by investigators trained in qualitative methods, using an interview guide to elicit conversation. recordings of each group were transcribed. three reviewers analyzed the text in a multi-stage iterative process to code the data, describe the main categories, and identify unifying themes. results: participants included emts, paramedics, physicians, and nurses. clinical experience ranged from months to years. recurrent thematic domains when discussing attitudes and beliefs were: perceptions of respect and competence, professionalism, teamwork, value assigned to the process, and professional duty. modifiers of these domains were: hierarchy, skill/training level, severity/type of patient illness, and system/ regulatory factors. strategies to improving barriers to the handoff included: fostering familiarity and personal connections between ems and ed staff, encouraging two-way conversations, feedback, and direct interactions between ems providers and ed physicians, and optimizing ways for ems providers to share subjective impressions (beyond standardized data elements) with hospital-based care teams. conclusion: ems professionals assign high value to the ed handoff. variations in patient acuity, familiarity with other handoff participants, and perceptions of respect and professionalism appear to influence the perceived quality of this transition. regulatory strategies to standardize the contents of the handoff may not alone overcome barriers to this process. miology, public health) then developed an approach to assign ems records to one of symptom-based illness categories (gastrointestinal illness, respiratory, etc). ems encounter records were characterized into these illness categories using a novel text analytic program. event alerts were identified across the state and local regions in illness categories using either change detection from baseline with (cusum) analysis (three standard deviations) and a novel text-proportion (tap) analysis approach (sas institute, cary, nc). results: . million ems encounter records over a year period were analyzed. the initial analysis focused upon gastrointestinal illness (gi) given the potential relationship of gi distress to infectious outbreaks, food contamination and intentional poisonings (ricin). after accounting for seasonality, a significant gi event was detected in feb (see red circle on graph). this event coincided with a confirmed norovirus outbreak. the use of cusum approach (yellow circle on graph) detected the alert event on jan , . the novel tap approach on a regional basis detected the alert on dec , . conclusion: ems has the advantage of being an early point of contact with patients and providing information on the location of insult or injury. surveillance based on ems information system data can detect emergent outbreaks of illness of interest to public health. a novel text proportion analytic technique shows promise as an early event detection method. assessing chronic stress in the emergency medical services elizabeth a. donnelly , jill chonody university of windsor, windsor, on, canada; university of south australia, adelaide, australia background: attention has been paid to the effect of critical incident stress in the emergency medical services (ems); however, less attention has been given to the effect of chronic stress (e.g., conflict with administration or colleagues, risk of injury, fatigue, interference in non-work activities) in ems. a number of extant instruments assess for workplace stress; however, none address the idiosyncratic aspects of work in ems. objectives: the purpose of this study was to validate an instrument, adapted from mccreary and thompson ( ) , that assesses levels of both organizational and operational work-related chronic stress in ems personnel. methods: to validate this instrument, a cross-sectional, observational web-based survey was used. the instrument was distributed to a systematic probability sample of emts and paramedics (n = , ). the survey also included the perceived stress scale (cohen, ) to assess for convergent construct validity. results: the survey attained a . % usable response rate (n = ); respondent characteristics were consistent across demographic characteristics with other studies of emts and paramedics. the sample was split in order to allow for exploratory and confirmatory fac-tor analyses (n = /n = ). in the exploratory factor analysis, principal axis factoring with an oblique rotation revealed a two-factor, -item solution (kmo = . , v = . , df = , p £. ). confirmatory factor analysis suggested a more parsimonious, two-factor, -item solution (v = . , df = , p £ . , rmsea = . , cfi = . , tli = . , srmr = . ). the factors demonstrated good internal reliability (operational stress a = . , organizational stress a = . ). both factors were significantly correlated (p £ . ) with the hypothesized convergent validity measure. conclusion: theory and empirical research indicate that exposure to chronic workplace stress may play an important part in the development of psychological distress, including burnout, depression, and posttraumatic stress disorder (ptsd). workplace stress and stress reactions may potentially interfere with job performance. as no extant measure assesses for chronic workplace stress in ems, the validation of this chronic stress measure enhances the tools ems leaders and researchers have in assessing the health and well-being of ems providers. effect of naltrexone background: survivors of sarin and other organophosphate poisoning can develop delayed encephalopathy that is not prevented by standard antidotal therapy with atropine and pralidoxime. a rat model of poisoning with the sarin analogue diisoprophylfluorophosphate (dfp) demonstrated impairment of spatial memory despite antidotal therapy with atropine and pralidoxime. additional antidotes are needed after acute poisonings that will prevent the development of encephalopathy. objectives: to determine the efficacy of naltrexone in preventing delayed encephalopathy after poisoning with the sarin analogue dfp in a rat model. the hypothesis is that naltrexone would improve performance on spatial memory after acute dfp poisoning. the sarin analogue dfp was used because it has similar toxicity to sarin while being less dangerous to handle. methods: a randomized controlled experiment at a university animal research laboratory of the effects of naltrexone on spatial memory after dfp poisoning was conducted. long evans rats weighing - grams were randomized to dfp group (n = , rats received a single intraperitoneal (ip) injection of dfp mg/kg) or dfp+naltrexone group (n = , rats received a single ip injection of dfp ( mg/kg) followed by naltrexone mg/kg/day). after injection, rats were monitored for signs and symptoms of cholinesterase toxicity. if toxicity developed, antidotal therapy was initiated with atro-background: one of the primary goals of management of patients presenting with known or suspected acetaminophen (apap) ingestion is to identify the risk for apap-induced hepatotoxicity. current practice is to measure apap level at a minimum of hours post ingestion and plot this value on the rumack-matthew nomogram. one retrospective study of apap levels drawn less than hours post-ingestion found a level less than mcg/ml to be sufficient to exclude toxic ingestion. objectives: the aim of this study was to prospectively determine the negative predictive value (npv) for toxicity of an apap level of less than mcg/ml obtained less than hours post-ingestion. methods: this was a multicenter prospective cohort study of patients presenting to one of five tertiary care hospitals that are part of the toxicology investigator's consortium (toxic). eligible patients presented to the emergency department less than hours after known or suspected ingestion and had the initial apap level obtained at greater than but less than hours post ingestion. a second apap level was obtained at hours or more post-ingestion and plotted on the rumack-matthew nomogram to determine risk of toxicity. the outcome of interest was the npv of an initial apap level less than mcg/ml. a power analysis based on an alpha = . and power of . yielded the requirement of subjects. results: data were collected on patients over a month period from may to nov . patients excluded from npv analysis consisted of: initial apap level greater than mcg/ml ( ), negligible apap level on both the initial and confirmatory apap level ( ), initial apap level drawn less than one hour after ingestion ( ), or an unknown time of ingestion ( ). ninety-three patients met the eligibility criteria. two patients ( . %) with an initial apap level less than mcg/ml ( mcg/ml at min, mcg/ml at min) were determined to be at risk for toxicity based on oh s saem annual meeting abstracts implementation of an emergency department sign-out checklist improves patient hand-offs at change of shift nicole m ma computer-assisted self-interviews improve testing for chlamydia and gonorrhea in the pediatric emergency department is the australian triage system a better indicator of psychiatric patients' needs for intervention than the ena emergency severity index triage system? patients were given an initial dose of mg droperidol intramuscularly followed by an additional dose of mg after min if required. inclusion criteria were patients requiring physical restraint and parenteral sedation. the primary outcome was the time to sedation. secondary outcomes were the proportion of patients requiring additional sedation within the first hour, over-sedation measured as - on the sedation assessment tool, and respiratory compromise measured as oxygen saturation < %. results: droperidol was administered to patients and of these had sedation scores documented. presentations included % with alcohol intoxication. dose ranged from . mg to mg, median mg (interquartile range conclusion: droperidol is effective for rapid sedation for abd and rarely causes over-sedation serum creatinine (scr) is widely used to predict risk; however, gfr is a better assessment of kidney function. objectives: to compare the ability of gfr and scr to predict the development of cin among ed patients receiving cects. we hypothesized that gfr would be the best available predictor of cin. methods: this was a retrospective chart review of ed patients ‡ years old who had a chest or abdomen/pelvis cect between / / and / / . baseline and follow-up scr levels were recorded. patients with initial scr > . mg/dl were excluded, as per hospital radiology department protocol. cin was defined as a scr increase of either %, . mg/dl, or a gfr decrease of % within hours of contrast exposure. gfr was calculated using the ckd epi and mdrd formulae, and analyzed in original units and categorized form (< , ‡ ) with each additional unit decrease in ckd epi, subjects were % more likely to develop cin (or = . ) (p < . ). additionally, subjects with ckd epi < were . (or) times more likely to have cin than subjects with ckd epi ‡ in original units, ckd epi (p < . ) and mdrd (p < . ) both had a significantly higher auc than scr. conclusion: age, as an independent variable, is the best predictor of cin, when compared with scr and gfr. due to a small number of cases with cin, the confidence intervals associated with the odds ratios are wide. future research should focus on patient risk stratification and establishing ed interventions to prevent cin. a rat model of carbon monoxide induced neurotoxicity heather ellsworth non-traumatic subarachnoid hemorrhage diagnosed by lumbar puncture following non-diagnostic head ct: a retrospective case-control study and decision a dass score of > has been previously defined as an indicator of increased stress levels. multivariable logistic regression was utilized to identify demographic and work-life characteristics significantly associated with stress. results: . % of individuals responded to the survey ( , / , ) and prevalence of stress was estimated at . %. the following work-life characteristics were associated with stress: certification level, work experience, and service type. the odds of stress in paramedics was % higher when compared to emt-basics (or = . , % ci = . - . ). when compared to £ years of experience - . ) were more likely to be stressed. ems professionals working in county (or = ci = . - . ) and private services (or = ) were more likely than those working in fire-based services to be stressed. the following demographic characteristics were associated with stress: general health and smoking status finally, former smokers (or = . , % ci = . - . ) and current smokers (or = . , % ci = . - . ) were more likely to be stressed than non-smokers literature suggests this is within the range of stress among nurses, and lower than physicians. while the current study was able to identify demographic and work-life characteristics associated with stress, the long-term effects are largely unknown methods: design: prospective randomized controlled trial. subjects: female sus scrofa swine weighing - kg were infused with amitriptyline . mg/kg/minute until the map fell to % of baseline values. subjects were then randomized to experimental group (ife ml/kg followed by an infusion of . ml/kg/minute) or control group (sb meq/kg plus equal volume of normal saline). interventions: we measured continuous heart rate (hr), sbp, map, cardiac output (co), systemic vascular resistance (svr), and venous oxygen saturation (svo ). laboratory values monitored included ph, pco , bicarbonate, lactate, and amitriptyline levels. descriptive statistics including means, standard deviations, standard errors of measurement, and confidence limits were calculated. results: of swine, seven each were allocated to ife and sb groups. there was no difference at baseline for each group regarding hr, sbp, map, co, svr, or svo . ife and sb groups required similar mean amounts of tca to reach hypotension one ife and two sb pigs survived. conclusion: in this interim data analysis of amitriptyline-induced hypotensive swine, we found no difference in mitigating hypotension between ife and sb lipid rescue : a survey of poison center medical directors regarding intravenous fat emulsion therapy michael r. christian , erin m. pallasch cook county hospital (stroger), chicago, il reliability of non-toxic acetaminophen concentrations obtained less than hours after ingestion evaluating age in the field triage of injured background: hiv screening in eds is advocated to achieve the goal of comprehensive population screening. yet, hiv testing in the ed is sometimes thwarted by a patient's condition (e.g. intoxication) or environmental factors (e.g. other care activities). whether it is possible to test these patients at a later time is unknown. objectives: we aimed to determine if ed patients who were initially unable to receive an hiv testing offer might be tested in the ed at a later time. we hypothesized that factors preventing testing are transient and that there are subsequent opportunities to repeat testing offers. methods: we reviewed medical records for patients presenting to an urban, academic ed who were approached consecutively to offer hiv testing during randomly selected periods from january to january . patients for whom the initial attempted offer could not be completed were reviewed in detail with standardized abstraction forms, duplicate abstraction, and third-party discrepancy adjudication. primary outcomes included repeat hiv testing offers during that ed visit, and whether a testing offer might eventually have been possible either during the initial visit or at a later visit within months. outcomes are described as proportions with confidence intervals. results: of patients approached, initial testing offers could not be completed for ( %). these were % male, % white, and had a median age of ( - ). a repeat offer of testing during the initial visit would have been possible for / ( %), and / ( %) were actually offered testing on repeat approach. of the for whom a testing offer would not have been possible on the initial visit, ( %) had at least one additional visit within months, and / ( %) could have been offered testing on at least one visit. overall, a repeat testing offer would have been possible for / ( %, % ci - %). conclusion: factors preventing an initial offer of hiv testing in the ed are generally transient. opportunities for repeat approach during initial or later ed encounters suggest that, given sufficient resources, the ed could succeed in comprehensively screening the population presenting for care. ed screening personnel who are initially unable to offer testing should repeat their attempt. hiv adopt an ''opt-out'' rapid hiv screening model in order to identify hiv infected patients. previous studies nationwide have shown acceptance rates for hiv screening of - % in emergency departments. however, it is unknown how acceptance rates will vary in a culturally and ethnically diverse urban emergency department.objectives: to determine the characteristics of patients who accept or refuse ''opt-out'' hiv screening in an urban emergency department.methods: a self-administered, anonymous survey is administered to ed patients who are to years of age. the questionnaire is administered in english, russian, mandarin, and spanish. questions include demographic characteristics, hiv risk factors, perception of hiv risk, and acceptance of rapid hiv screening in the emergency department. results: to date patients responded to our survey. of the , ( . %) did not accept an hiv test (group ) in their current ed visit and ( . %) accepted an hiv test (group ). the major two reasons given for opting out (i.e., group ) was ''i do not feel that i am at risk'' ( . %) and ''i have been tested for hiv before'' ( . %). there was no difference between the groups in regards to sex (p = . ), age (p = . ), religious affiliation (p = . ), marital status (p = . ), language spoken at home (p = . ), and whether they had been hiv tested before ( . % in group and . % in group ; p = . ). however, there was a statistically significant difference with regards to educational level and income. more patients in group ( . %) and . % in group had less than a college level education (p < . ). similarly, more patients in group ( . %) and only . % in group had an annual household income of £$ , (p < . ). conclusion: in a culturally and ethnically diverse urban emergency department, patients with a lower socioeconomic status and educational level tend to opt out of hiv screening test offered in the ed. no significant difference in acceptance of ed hiv testing was found to date based on primary language spoken at home or religious affiliation background: antimicrobial resistance is a problem that affects all emergency departments. objectives: our goal was to examine all urinary pathogens and their resistance patterns from urine cultures collected in the emergency department (ed).methods: this study was performed at an urban/suburban community-teaching hospital with an annual volume of , visits. using electronic records, all cases of urine cultures received in were reviewed for data including type of bacteria, antibiotic resistance, and health care exposure (hcx). hcx was defined as no prior hospitalization within the previous six months, hospitalization within the previous three months, hospitalization within the previous six months, nursing home resident (nh), and presence of an indwelling urinary catheter (uc). an investigator abstracted all data with a second re-abstracting a random % for kappa statistics between . and . . group background: approximately - % of patients treated with epinephrine for anaphylaxis receive a second dose but the risk factors associated with repeat epinephrine use remain poorly defined. objectives: to determine whether obesity is a risk factor for requiring + epinephrine doses for patients who present to the emergency department (ed) with anaphylaxis due to food allergy or stinging insect hypersensitivity. methods: we performed a retrospective chart review at four tertiary care hospitals that care for adults and children in new england between the following time periods: massachusetts general hospital ( / / - / / ), brigham and women's hospital ( / / - / / ), children's hospital boston ( / / - / / ), hasbro children's hospital ( / / - / / ). we reviewed the medical records of all patients presenting to the ed for food allergy or stinging insect hypersensitivity using icd cm codes. we focused on anthropomorphic data and number of epinephrine treatments given before and during the ed visit. among children, calculated bmis were classified according to cdc growth indicators as underweight, healthy, overweight, or obese. all patients who presented on or after their th birthday were considered adults.background: transitions of care are ubiquitous in the emergency department (ed) and inevitably introduce the opportunity for errors. despite recommendations in the literature, few emergency medicine (em) residency programs provide formal training or standard process for patient hand-offs. checklists have been shown to be effective quality improvement measures in inpatient settings and may be a feasible method to improve ed hand-offs. objectives: to determine if the use of a sign-out checklist improves the accuracy and efficiency of resident sign-out in the ed as measured by reduced omission of key information, communication behaviors, and time to sign-out each patient. methods: a prospective study of first-and second-year em and non-em residents rotating in the ed at an urban academic medical center with an annual ed volume of , . trained clinical research assistants observed resident sign-out during shift change over a two-week period and completed a -point binary observable behavior data collection tool to indicate whether or not key components of sign-out occurred. time to sign out each patient was recorded. we then created and implemented a computerized sign-out checklist consisting of key elements that should be addressed during transitions of care, and instructed residents to use this during hand-offs. a two-week post-intervention observation phase was conducted using the same data collection tool. proportions, means, and non-parametric comparison tests were calculated using stata. results: one hundred fifteen sign-outs were observed prior to checklist implementation and after; one sign-out was excluded for incompleteness. significant improvements were seen in four of the measured signout components: inclusion of history of present illness increased by % (p < . ), likely diagnosis increased by % (p = . ), disposition status increased by % (p < . ), and patient/care team awareness of plan increased by % (p < . ). (figure ) time data for sign-outs pre-implementation and post-implementation were available. seven sign-outs were excluded for incompleteness or spurious values. mean length of sign out was s ( % ci to ) and . s ( % ci to ) per patient. conclusion: implementation of a checklist improved the transfer of information but did not affect the overall length of time for the sign-out. the objectives: to determine risk factors associated with adult patients presenting to the ed with cellulitis who fail initial antibiotic therapy and require a change of antibiotics or admission to hospital. methods: this was a prospective cohort study of patients ‡ years presenting with cellulitis to one of two tertiary care eds (combined annual census , ). patients were excluded if they had been treated with antibiotics for the cellulitis prior to presenting to the ed, if they were admitted to hospital, or had an abscess only. trained research personnel administered a questionnaire at the initial ed visit with telephone follow-up weeks later. patient characteristics were summarized using descriptive statistics and % confidence intervals (cis) were estimated using standard equations. backwards stepwise multivariable logistic regression models determined predictor variables independently associated with treatment failure (failed initial antibiotic therapy and required a change of antibiotics or admission to hospital). results: patients were enrolled, were excluded, and were lost to follow-up. the mean (sd) age was . ( . ) and . % were male. ( . %) patients were given antibiotics in the ed. ( . %) were given oral, ( . %) were given iv, and ( . %) patients were given both oral and iv antibiotics. ( . %) patients had a treatment failure. fever (temp > °c) at triage (or: . , % ci: . , . ), leg ulcers (or: . , % ci: . , . ), edema or lymphedema (or: . , % ci: . , . ), and prior cellulitis in the same area (or: . , % ci: . , . ) were independently associated with treatment failure. conclusion: this analysis found four risk factors associated with treatment failure in patients presenting to the ed with cellulitis. these risk factors should be considered when initiating empiric outpatient antibiotic therapy for patients with uncomplicated cellulitis. use background: children presenting for care to a pediatric emergency department (ped) commonly require intravenous catheter (iv) placement. prior studies report that the average number of sticks to successfully place an iv in children is . . successfully placing an iv requires identification of appropriate venous access targets. the veinviewer visionÒ (vvv) assists with iv placement by projecting a map of subcutaneous veins on the surface of the skin using near infrared light. objectives: to compare the effectiveness of the vvv versus standard approaches: sight (s) and sight plus palpation (s+p) for identifying peripheral veins for intravenous catheter placement in children treated in a ped. methods: experienced pediatric emergency nurses and physicians identified peripheral venous access targets appropriate for intravenous cannulation of a cross-sectional convenience sample of english speaking children aged - years presenting for treatment of sub-critical injury or illness whose parents provided consent. the clinicians marked the veins with different colored washable marker and counted them on the dorsum of the hand and in the antecubital fossa using the three approaches: s, s+p, and vvv. a trained research assistant photographed each site for independent counting after each marking and recorded demographics and bmi. counts were validated using independent photographic analyses. data were entered into sas . and analyzed using paired t-tests. results: patients completed the study. clinicians were able to identify significantly more veins on the dorsum of the hand using vvv than s alone or s+p, . (p < . , ci . - . ) and . (p < . , ci . - . ), respectively, as well as significantly more veins in the antecubital fossa using vvv than s alone or s+p, . (p < . , ci . - . ) and . (p < . , ci . - . ), respectively. the differences in numbers of veins identified remained significant at p < . level across all ages, races, and bmis of children and across clinicians and validating independent photographic analyses. conclusion: experienced emergency nurses and physicians were able to identify significantly more venous access targets appropriate for intravenous cannulation in the dorsum of the hand and antecubital fossa of children presenting for treatment in a ped using vvv than the standard approaches of sight or sight plus palpation. an background: mental health emergencies have increased over the past two decades, and contribute to the ongoing rise in u.s. ed visit volumes. although data are limited, there is a general perception that the availability of in-person psychiatric consultation in the ed and of inpatient psychiatric beds is inadequate. objectives: to examine the availability of in-person psychiatry consultation in a heterogeneous sample of u.s. eds, and typical delays in transfer of ed patients to an inpatient psychiatric bed. methods: during - , we mailed a survey to all ed directors in a convenience sample of nine us states (ar, co, ga, hi, ma, mn, or, vt, and wy). all sites were asked: ''are psychiatric consults available in-person to the ed?'' (yes/no), with affirmative respondents asked about the typical delay. sites also were asked about typical ed boarding time between a request for patient transfer and actual patient departure from the ed to an inpatient psychiatric bed. ed characteristics included rural/urban location, visit volume (visits/hour), admission rate, ed staffing, and the proportion of patients without insurance. data analysis used chi-square tests and multivariable logistic regression. results: surveys were collected from ( %) of the eds, with > % response rate in every state. overall, only % responded that psychiatric consults were available in-person to the ed. in multivariable logistic regression, ed characteristics independently associated with lack of in-person psychiatric consultation were: location within specific states (eg, ar, ga), rural location, lower visit volume, and lower admission rate. among the subset of eds with psychiatric consults available, % reported a typical wait time of at least hour. overall, % of eds reported that the typical time from request to actual patient transfer to an inpatient psychiatric bed was > hours, and % reported a maximum time in past year of > day (median days, iqr - ). in a multivariable model, location in ma and higher visit volume were associated with greater odds of a maximum wait time of > day. conclusion: among surveyed eds in nine states, only % have in-person psychiatric consultants available. moreover, approximately half of eds report boarding times of > h from request for transfer to actual departure to an inpatient psychiatric bed.background: many emergency departments (ed) in the united states use a five tiered triage protocol that has a limited evaluation of psychiatric patients. the australian triage scale (ats), a psychiatric triage system, has been used throughout australia and new zealand since the early s. objectives: the objective of the study is to compare the current triage system, emergency nurses association (ena) esi -tier, to the ats for the evaluation of the psychiatric patients presenting to the ed. methods: a convenience sample of patients, years of age and older, presenting with psychiatric complaints at triage were given the ena triage assessment by the triage nurse. a second triage assessment, performed by a research fellow, included all observed and reported elements using the ats protocol, a self-assessment survey and an agitation assessment using the richmond agitation sedation scale (rass). the study was performed at an inner city level i trauma center with , visits per year. the ed was a catchment facility for the police department for psychiatric patients in the area. patients were excluded if they were unstable, unable to communicate, or had a non-psychiatric complaint. results were analyzed in spss v . the analysis of data used frequencies, descriptive and anova. results: a total of patients were enrolled in the study: % were african american, % caucasian, % hispanic, % asian, and % indian; % of subjects enrolled were male. the patients' level of agitation using rass showed % were alert and calm, % were restless and anxious, % were agitated, and % combative, violent, or dangerous to self. the only significant correlation found was among the ats and several self assessment questions: ''i feel agitated on a to scale'' (p = . ) and ''i feel violent on a to scale'' (p = . ). there were no significant correlations found among the ena triage, rass scores, and throughput times. conclusion: the ats test was more sensitive to the patient declaring that he or she was agitated or felt violent. this shows that this system might be a more useful system in determining the severity of need of psychiatric patients presenting to the ed. variations background: hemoglobin-based oxygen carriers (hbocs) have been evaluated for small-volume resuscitation of hemorrhagic shock due to their oxygen carrying capability, but have found limited utility due to vasoactive side-effects from nitric oxide (no) scavenging. objectives: to define an optimal hboc dosing strategy and evaluate the effect of an added no donor, we use a prehospital swine polytrauma model to compare the effect of low-vs. moderate-volume hboc resuscitation with and without nitroglycerin (ntg) co-infusion as an no donor. we hypothesize that survival time will improve with moderate resuscitation and that an no donor will add additional benefit. methods: survival time was compared in groups (n = ) of anesthetized swine subjected to simultaneous traumatic brain injury and uncontrolled hemorrhagic shock by aortic tear. animals received one of three different resuscitation fluids: lactated ringers (lr), hboc, or vasoattenuated hboc with ntg co-infusion. for comparison, these fluids were given in a severely limited fashion (sl) as one bolus every minutes up to four total, or a moderately limited fashion (ml) as one bolus every minutes up to seven total, to maintain mean arterial pressure ‡ mmhg. comparison of resuscitation regimen and fluid type on survival time was made using two-way anova with interaction and tukey kramer adjustment for individual comparisons. results: there was a significant interaction between fluid regimen and resuscitation fluid type (anova, p = . ) indicating that the response to sl or ml resuscitation was fluid type-dependent. within the lr and hboc+ntg groups, survival time (mean, %ci) was longer for sl, . min ( injuries are common and result from many different mechanisms of injury (moi). knowing common fracture locations may help in diagnosis and treatment, especially in patients presenting with distracting injuries that may mask the pain of a radius fracture.objectives: we set out to determine the incidence of radius fracture locations among patients presenting to an urban emergency department (ed).background: carbon monoxide (co) is the leading cause of poisoning morbidity and mortality in the united states. standard treatment includes supplemental oxygen and supportive care. the utility of hyperbaric oxygen (hbo) therapy has been challenged by a recent cochrane review. hypothermia may mitigate delayed neurotoxic effects after co poisoning as it is effective in cardiac arrest patients with similar neuropathology. objectives: to develop a rat model of acute and delayed severe co toxicity as measured by behavioral deficits and cell necrosis in post-sacrifice brain tissue.methods: a total of rats were used for model development; variable concentrations of co and exposure times were compared to achieve severe toxicity. for the protocol, six senescent long evans rats were exposed to , ppm of co for minutes then , ppm for minutes, followed by three successive dives at , ppm with an endpoint of apnea or seizure; there was a brief interlude between dives for recovery. a modified katz assessment tool was used to assess behavior at baseline and hours, day, and , , , , , and weeks post-exposure. following this, the brains were transcardially fixed with formalin, and lm sagittal slices were embedded in paraffin and stained with hematoxylin and eosin. a pathologist quantified the percentage of necrotic cells in the cortex, hippocampus (pyramidal cells), caudoputamen, cerebellum (purkinje cells), dentate gyrus, and thalamus of each brain to the nearest % from randomly selected high power fields ( x background: there remains controversy about the cardiotoxic effects of droperidol, and in particular the risk of qt prolongation and torsades des pointes (tdp).objectives: this study aimed to investigate the cardiac and haemodynamic effects of high-dose parenteral droperidol for sedation of acute behavioural disturbance (abd) in the emergency department (ed). methods: a standardised intramuscular (im) protocol for the sedation of ed patients with abd was instituted as part of a prospective observational safety study in four regional and metropolitan eds. patients with abd were given an initial dose of mg droperidol followed by an additional dose of mg after min if required. inclusion criteria were patients requiring physical restraint and parenteral sedation. the primary outcome was the proportion of patients who have a prolonged qt interval on ecg. the qt interval was plotted against the heart rate (hr) on the qt nomogram to determine if the qt was abnormal. secondary outcomes were frequency of hypotension and cardiac arrhythmias. results: ecgs were available from of patients with abd given droperidol. the median dose was mg (iqr - mg; range: to mg). the median age was years (rnge: to ) and were males ( %). a total of four ( %) qt-hr pairs were above the ''at-risk'' line on the qt nomogram. transient hypotension occurred in ( %), and no arrhythmias were detected.conclusion: droperidol appears to be safe when used for rapid sedation in the dose range of to mg. it rarely causes hypotension or qt prolongation. blood background: soldiers and law enforcement agents are repeatedly exposed to blast events in the course of carrying out their duties during training and combat operations. little data exist on the effect of this exposure on the physiological function of the human body. both military and law enforcement dynamic entry personnel, ''breachers'', began expressing sensitivity to the risk of injury as a result of multiple blast exposures. breachers apply explosives as a means of gaining access to barricaded or hardened structures. these specialists can be exposed to as many as a dozen lead-encased charges per day during training exercises.objectives: this observational study was performed by the breacher injury consortium to determine the effect of short-term exposure to blasts by breachers on whole blood lead levels (blls) and zinc protoporphyrin levels (zppls). methods: two -week basic breaching training classes were conducted by the united states marine corps' weapons training battalion dynamic entry school. each class included students and up to three instructors, with six non-breaching marines serving as a control group. to evaluate for lead exposure, venous blood samples were acquired from study participants on the weekend prior and following training in the first training class, whereas the second training class had an additional level performed mid-training. blls and zppls were measured in a whole-blood sample using the furnace atomic absorption method and hematofuorimeter method, respectively. results: analysis of these blast injury data indicated students demonstrated significantly increased blls post-explosion (mean = mcg/dl, sd . , p < . ) compared to pre-training (mean = mcg/dl, sd . ) and control subjects (mean = mcg/dl, sd . , p < . ). instructors also demonstrated significantly increased blls post explosion (mean = mcg/dl, sd . , p < . ) compared to pre-training (mean = mcg/ dl, sd . ) and control subjects (mean = mcg/dl, sd . , p < . ). student and instructor zppls were not significantly different in post-training compared to pretraining or control groups. conclusion: the observation from this study that breachers are at risk of mild increases in blls support the need for further investigation into the role of lead following repeated blast exposure with munitions encased in lead. direct observation of the background: notification of a patient's death to family members represents a challenging and stressful task for emergency physicians. complex communication skills such as those required for breaking bad news (bbn) are conventionally taught with small-group and other interactive learning formats. we developed a de novo multi-media web-based learning (wbl) module of curriculum content for a standardized patient interaction (spi) for senior medical students during their emergency medicine rotation.objectives: we proposed that use of an asynchronous wbl module would result in students' skill acquisition for breaking bad news. methods: we tracked module utilization and performance on the spi to determine whether students accessed the materials and if they were able to demonstrate proficiency in its application. performance on the spi was assessed utilizing a bbn-specific content instrument developed from the griev_ing mnemonic as well as a previously validated instrument for assessing communication skills.results: three hundred seventy-two students were enrolled in the bbn curriculum. there was a % completion rate of the wbl module despite students being given the option to utilize review articles alone for preparation. students interacted with the activities within the module as evidenced by a mean number of mouse clicks of . (sd . ). overall spi scores were . %, (sd . ) with content checklist scores of . % (sd . ) and interpersonal communication scores . % (sd . ). five students had failing content scores (< %) on the spi and had a mean number of clicks of . (sd . ), which is not significantly lower than those passing (p = . ). students in the first year of wbl deployment completed self-confidence assessments which showed significant increases in confidence ( . tobackground: pelvis ultrasonography (us) is a useful bedside tool for the evaluation of women with suspected pelvic pathology. while pelvic us is often performed by the radiology department, it often lacks clinical correlation and takes more time than bedside us in the ed. this was a prospective observational study comparing the ed length of stay (los) of patients receiving ed us versus those receiving radiology us. objectives: the primary objective was to measure the difference in ed los. the secondary objectives were to ) assess the role of pregnancy status, ob/gyn consult in the ed, and disposition, in influencing the ed los; and ) to assess the safety of ed us by looking at patient return to the ed within weeks and whether that led to an alternative diagnosis.methods: subjects were women over years old presenting with a gi or gu complaint, and who received either an ed or radiology us. a t-test was used for the primary objective, and linear regression to test the secondary objective. odds ratios were performed to assess for interaction between these factors and type of ultrasound. subgroup analyses were performed if significant interaction was detected. results: forty-eight patients received an ed us and patients received a radiology us. subjects receiving an ed us spent minutes less in the ed (p < . ). in multivariate analysis, even when controlling for pregnancy status, ob/gyn consult, and disposition, patients who received an ed us had a los reduction of minutes (p < . ). in odds ratio analysis, patients who were pregnant were times more likely to have received an ed us (p < . ). patients who received an ob/gyn consult in the ed were five times more likely to receive a radiology us (p < . ). there was no association between type of us and disposition. in subgroup analyses, pregnant and non-pregnant patients who received an ed us still had a los reduction of minutes (p < . ) and minutes (p < . ), respectively. sample sizes were inadequate for subgroup analysis for subjects who had ob/gyn consults. in patients who did not receive an ob/gyn consult, those who received an ed us had a los reduction of minutes (p < . ). finally, % of subjects returned within two weeks, but none led to an alternative diagnosis. conclusion: even when controlling for disposition, ob/gyn consultation, and pregnancy status, patients who received an ed us had a statistically and clinically significant reduction in their ed los. in addition, ed us is safe and accurate. background: although early surface cooling of burns reduces pain and depth of injury, there are concerns that cooling of large burns may result in hypothermia and worse outcomes. in contrast, controlled mild hypothermia improves outcomes after cardiac arrest and traumatic burn injury. objectives: the authors hypothesized that controlled mild hypothermia would prolong survival in a fluidresuscitated rat model of large scald burns. methods: forty sprague-dawley rats ( - g) were anesthetized with mg/kg intramuscular ketamine and mg/kg xylazine, with supplemental inhalational isoflurane as needed. a single full-thickness scald burn covering % of the total body surface area was created per rat using a mason-walker template placed in boiling water ( deg c) for a period of seconds. the rats were randomized to hypothermia (n = ) and nonhypothermia (n = ). core body temperature was continuously monitored with a rectal temperature probe. hypothermia was induced through intraperitoneal injection of cooled ( deg c) saline. the core temperature was reduced by deg c and maintained for a period of hours, applying an ice or heat pack when necessary. the rats were then rewarmed back to baseline temperature. in the control group, room temperature saline was injected into the intraperitoneal cavity and core temperature was maintained using a heating pad as needed. the rats were monitored until death or for a period of days, whichever was greater. the primary outcome was death. the difference in survival was determined using a kaplan-meier analysis or log rank test. results: the mean core temperatures were . deg c for the hypothermic group and . deg c for the normothermic group. the mean survival times were hours for the hypothermic group ( % confidence interval [ci] = to ) and hours for the normothermic group ( % ci = to ). the seven-day survival rates in the hypothermic and non-hypothermic groups were % and %. these differences were not significant, p = . for both comparisons. conclusion: induction of brief mild hypothermia increases but does not significantly prolong survival in a resuscitated rat model of large scald burns. serum objectives: we sought to determine levels of serum mtdna in ed patients with sepsis compared to controls and the association between mtdna and both inflammation and severity of illness among patients with sepsis. methods: prospective observational study of patients presenting to one of three large, urban, tertiary care eds. inclusion criteria: ) septic shock: suspected infection, two or more systemic inflammatory response (sirs) criteria, and systolic blood pressure (sbp) < mmhg despite a fluid bolus; ) sepsis: suspected infection, two or more sirs criteria, and sbp > mmhg; and ) control: ed patients without suspected infection, no sirs criteria, and sbp > mmhg. three mtdnas (cox-iii, cytochrome b, and nadh) were measured using real-time quantitative pcr from serum drawn at enrollment. il- and il- were measured using a bio-plex suspension array system. baseline characteristics, il- , il- , and mtdnas were compared using one way anova or fisher exact test, as appropriate. correlations between mtdnas and il- /il- were determined using spearman's rank. linear regression models were constructed using sofa score as the dependent variable, and each mtdna as the variable of interest in an independent model. a bonferroni adjustment was made for multiple comparisons.results: of patients, were controls, had sepsis, and had septic shock. we found no significant difference in any serum mtdnas among the cohorts (p = . to . ). all mtdnas showed a small but significant negative correlation with il- and il- (q = ) . to ) . ). among patients with sepsis or septic shock (n = ), we found a small but significant negative association between mtdna and sofa score, most clearly with cytochrome b (p = . ). conclusion: we found no difference in serum mtdnas between patients with sepsis, septic shock, and controls. serum mtdnas were negatively associated with inflammation and severity of illness, suggesting that as opposed to trauma, serum mtdna does not significantly contribute to the pathophysiology of the sepsis syndromes. methods: we consecutively enrolled ed patients ‡ years of age who met anaphylaxis diagnostic criteria from april to july at a tertiary center with , annual visits. we collected data on antihypertensive medications, suspected causes, signs and symptoms, ed management, and disposition. markers of severe anaphylaxis were defined as ) intubation, ) hospitalization (icu or floor), and ) signs and symptoms involving ‡ organ systems. antihypertensive medications evaluated included beta-blockers, angiotensin converting enzyme (ace) inhibitors, and calcium channel blockers (ccb). we conducted univariate and multivariate analyses to measure the association between antihypertensive medications and markers of severe anaphylaxis. because previous studies demonstrated an association between age and the suspected cause of the reaction with anaphylaxis severity, we adjusted for these known confounders in multivariate analyses. we report associations as odds ratios (ors) and corresponding % cis with p-values. results: among patients with anaphylaxis, median age (iqr) was ( - ) and ( . %) were female. eight ( . %) patients were intubated, ( %) required hospitalization, and ( %) had ‡ system involvement. forty-nine ( %) were on beta-blockers, ( %) on ace inhibitors, and ( . %) on ccb. in univariate analysis, ace inhibitors were associated with intubation and ‡ system involvement and ccb were associated with hospital admission. in multivariate analysis, after adjusting for age and suspected cause, ace inhibitors remained associated with hospital admission and beta-blockers remained associated with both hospital admission and ‡ system involvement. conclusion: in ed patients, beta-blocker and ace inhibitor use may predict increased anaphylaxis severity independent of age and suspected cause of the anaphylactic reaction. background: advanced cardiac life support (acls) resuscitation requires rapid assessment and intervention. some skills like patient assessment, quality cpr, defibrillation, and medication administration require provider confidence to be performed quickly and correctly. it is unclear, however, whether high-fidelity simulation can improve confidence with a multidisciplinary group of providers with high levels of clinical experience. objectives: the purpose of the study was to test the hypothesis that providers undergoing high-fidelity simulation of cardiopulmonary arrest scenarios will express greater confidence. methods: this was a prospective cohort study conducted at an urban level i trauma center from january to october with a convenience sample of registered (rn) and license practical nurses, nurse practitioners, resident physicians, and physician assistants who agreed to participate in / high-fidelity simulation (laerdal g) sessions of cardiopulmonary arrest scenarios about months apart. demographics were recorded. providers completed a validated preand post-test five-point likert scale confidence measurement tool before and after each session that ranged from not at all confident ( ) to very confident ( ) in recognizing signs and symptoms of, appropriately intervening in, and evaluating intervention effectiveness in cardiac and respiratory arrests. descriptive statistics, paired t-tests, and anova were used for data analysis. sensitivity testing evaluated subjects who completed their second session at months rather than months. results: sixty-five subjects completed consent, completed one session, and completed at least two background: prehospital studies have focused on the effect of health care provider gender on patient satisfaction. we know of no study that has assessed patient satisfication with patient and prehospital provider gender. some studies have shown higher patient satisfaction rates when cared for by a female health care provider.objectives: to determine the effect of ems provider gender on patient satisfaction with prehospital care. methods: a convenience sampling of all adult patients brought in to our ed, an urban level i trauma center by ambulance. a trained research associate (ra) stationed at triage conducted a survey using press ganey ems patient satisfaction questions. there were thirteen questions evaluating prehospital provider skills such as driving, courtesy, listening, medical care, and communication. each skill was assigned a point value between one and five; the higher the value the better the skill was performed. the patient's ambulance care report was copied for additional data extraction.results: a total of surveys were done. average patient age was , and % were female. scores for all questions totaled (mean . ± . ). prehospital providers pairings were: male-male (n = ), male-female (n = ), and female-female (n = ). there were no statistically significant differences in scores between our pairings (mean scores for male:male . , male:female . , and female:female . ; p = . ). we found nonstatistical differences in satisfaction scores based on the gender of the emt in the back of the ambulance: males had a mean score of . and females had a mean score of . (p = . ). we examined gender concordance by comparing gender of the patient to the gender of the prehospital provider and found that male-male had a mean score of . , female-female . , and when the patient and prehospital provider gender did not match, . (p = . ). conclusion: we found no effect of gender difference on patient satisfaction with prehospital care. we also found that overall, patients are very satisfied with their prehospital care. objectives: we set out to determine the sensitivity and specificity of eps in determining the presence of recently ingested tablets or tablet fragments.methods: this was a prospective volunteer study at an academic emergency department. healthy volunteers were enrolled and kept npo for hours prior to tablet ingestion. over minutes subjects ingested ml of water and tablets. ultrasounds video clips were performed prior to any tablet ingestion, after drinking ml of water, after tablets, after tablets, after tablets, and minutes after the final tablet ingestion yielding six clips per volunteer. all video clips were randomized and shown to three eps who were fellowship-trained in emergency ultrasound. eps recorded the presence or absence of tablets.results: ten volunteers underwent the pill ingestion protocol and sixty clips were collected. results for all cases and each rater are reported in the table. overall there was moderate agreement between raters (kappa = . ). sub-group analysis of , , or pills did not show any significant improvement in sensitivity and specificity.conclusion: ultrasound has moderate specificity but poor sensitivity for identification of tablet ingestion. these results imply that point-of-care ultrasound has limited utility in diagnosing large tablet ingestion. background: intravenous fat emulsion (ife) therapy is a novel treatment that has been used to reverse the acute toxicity of some xenobiotics with varied success. us poison control centers (pcc) are recommending this therapy for clinical use, but data regarding these recommendations are lacking.objectives: to determine how us pcc have incorporated ife as a treatment strategy for poisoning. methods: a closed-format multiple-choice survey instrument was developed, piloted, revised, and then sent electronically to every medical director of an accredited us pcc using surveymonkey in march ; addresses were obtained from the aapcc listserv, participation was voluntary and remained anonymous; three reminder invitations were sent during the study period. data were analyzed using descriptive statistics.results: forty-five of ( %) pcc medical directors completed the survey. all respondents felt that ife therapy played a role in the acute overdose setting. thirty ( %) pcc have a protocol for ife therapy: ( %) recommend an initial bolus of . ml/kg of a % lipid emulsion, ( %) pcc recommend an infusion of lipids, and / pcc recommend an initial infusion rate of . ml/kg of a % lipid emulsion. thirty-three ( %) felt that ife had no clinically significant side effects at a bolus dose of . ml/kg ( % emulsion). forty-four directors ( %) felt that the ''lipid sink'' mechanism contributed to the clinical effects of ife therapy, but ( %) felt that there was a yet undiscovered mechanism that likely contributed as well. in a scenario with cardiac arrest due to a single xenobiotic, directors stated that their center would always or often recommend ife after overdose of bupivicaine ( ; %), verapamil ( ; %), amitriptyline ( ; %), or an unknown xenobiotic ( ; %). in a scenario with significant hemodynamic instability due to a single xenobiotic, directors stated that their pcc would always or often recommend ife after overdose of bupivicaine ( ; %), verapamil ( ; %), amitriptyline ( ; %), or an unknown xenobiotic ( ; %).conclusion: ife therapy is being recommended by us pcc. protocols and dosing regimens are nearly uniform. most directors feel that ife is safe but are more likely to recommend ife in patients with cardiac arrest than in patients with severe hemodynamic compromise. further research is warranted. levels drawn at hours or more ( mcg/ml at hours, mcg ⁄ ml at hours, respectively). npv for toxic ingestion of an initial apap level less than mcg/ml was . % ( % ci . - . %).conclusion: an apap level of less than mcg/ml drawn less than hours after ingestion had a high npv for excluding toxic ingestion. however, the authors would not recommend reliance on levels obtained under hours to exclude toxicity as the potential for up to . % false negative results is considered unacceptable. background: genetic variations in the mu-opioid receptor gene (oprm ) mediate individual differences in response to pain and addiction.objectives: to study whether the common a g (rs ) mu-opioid receptor single nucleotide polymorphism (snp) or the alternative splicing snp of oprm (rs ) was associated with overdose severity, we assessed allele frequencies of each including associations with clinical severity in patients presenting to the emergency department (ed) with acute drug overdose. methods: in an observational cohort study at an urban teaching hospital, we evaluated consecutive adult ed patients presenting with suspected acute drug overdose over a -month period for whom discarded blood samples were available for analysis. specimens were linked with clinical variables (demographics, urine toxicology screens, clinical outcomes) then de-identified prior to genetic snp analysis. in-hospital severe outcomes were defined as either respiratory arrest (ra, defined by mechanical ventilation) or cardiac arrest (ca, defined by loss of pulse). blinded taqman genotyping (applied biosystems) of the snps were performed after standard dna purification (qiagen) and whole genome amplification (qiagen repli-g). the plink . genetic association analysis program was used to verify snp data quality, test for departure from hardy-weinberg equilibrium, and test individual snps for statistical association. results: we evaluated patients ( % female, mean age . ) who overall suffered ras and cas (of whom died). urine toxicology was positive in %, of which there were positives for benzodiazepines, cocaine, opiates, methadone, and barbiturates. all genotypes examined conformed to hardy-weinberg equilibrium. the g allele was associated with . fold increased odds of ca/ra (or . , p < . ). the rs mutant allele was not associated with ca/ ra. conclusion: these data suggest that the g mutant allele of the oprm gene is associated with worse clinical severity in patients with acute drug overdose. the findings add to the growing body of evidence linking the a g snp with clinical outcome and raise the question as to whether the a g snp may be a potential target for personalized medical prescribing practices with regard to behavioral/physiologic overdose vulnerability.