key: cord-0932101-3078sf4l authors: Morton, Sarah; Dawson, Jonathan; McLachlan, Sarah; McGuinness, William title: HEMS Out of Hospital Cardiac Arrests During the Initial COVID-19 Lockdown versus Non-Pandemic: A Comparison date: 2021-10-25 journal: Air Med J DOI: 10.1016/j.amj.2021.10.012 sha: 3db133022af6f472c81e7700485a89bcc5b48573 doc_id: 932101 cord_uid: 3078sf4l Introduction COVID-19 may have contributed to an excess of out-of-hospital cardiac arrests (OOHCAs). This observational study identified changes in OOHCA epidemiology pre and post COVID-19 lockdown in a single UK Helicopter Emergency Medicine (HEM) service. Methods A retrospective, single centre (Essex & Herts Air Ambulance), observational study was undertaken with anonymised OOHCA data (demographics, aetiology and outcomes) from 23rd March 2020– 23rd June 2020 and comparative data from 23rd March 2019-23rd June 2019. Supplementary data (total OOHCA's and patient outcomes) was provided by the East of England Ambulance Service NHS Trust. Data was analysed using the Mann-Whitney U test and Χ2 test; p-value <0.05 was statistically significant. Results 33.6% of HEMs activations during national lockdown were for OOHCAs compared with 25.8% during the reference time frame. The frequency of young and female OOHCAs demonstrated a statistically significant increase. Statistically significant variations in medical aetiology and initial cardiac rhythm were identified. Conclusion During the initial UK-wide lockdown, the OOHCA characteristics attended by one HEMS team altered. The changes seen may be due to the pathophysiology of COVID-19 or an alteration in dispatch due to the demand placed on the wider ambulance service; this may require further consideration for any future lockdowns or pandemics. COVID-19 may have contributed to an excess of out-of-hospital cardiac arrests (OOHCAs). This observational study identified changes in OOHCA epidemiology pre and post COVID-19 lockdown in a single UK Helicopter Emergency Medicine (HEM) service. A retrospective, single centre (Essex & Herts Air Ambulance), observational study was undertaken with anonymised OOHCA data (demographics, aetiology and outcomes) from 23 rd March 2020-23 rd June 2020 and comparative data from 23 rd March 2019-23 rd June 2019. Supplementary data (total OOHCA's and patient outcomes) was provided by the East of England Ambulance Service NHS Trust. Data was analysed using the Mann-Whitney U test and Χ 2 test; p-value <0.05 was statistically significant. Results 33.6% of HEMs activations during national lockdown were for OOHCAs compared with 25.8% during the reference time frame. The frequency of young and female OOHCAs demonstrated a statistically significant increase. Statistically significant variations in medical aetiology and initial cardiac rhythm were identified. During the initial UK-wide lockdown, the OOHCA characteristics attended by one HEMS team altered. The changes seen may be due to the pathophysiology of COVID-19 or an alteration in dispatch due to the demand placed on the wider ambulance service; this may require further consideration for any future lockdowns or pandemics. COVID-19, an infectious disease caused by the novel coronavirus (CoV) Severe Acute Respiratory Syndrome (SARS)-CoV-2, has been present in the United Kingdom (UK) since January 2020. 1 It was declared a pandemic by the World Health Organisation on the 11th March 2020, 2 necessitating a UK wide lockdown on the 23rd March 2020. 3 The ability to test people in the community was initially very limited, and it was not until September 2020 was testing freely available to the wider public. 4, 5 Anecdotally, during the pandemic there was an excess of Out of Hospital Cardiac Arrests (OOHCAs) with additional mortality [6] [7] [8] ; London Ambulance Service recorded an 81% relative increase between the 1st March-30th April 2020. 9 UK Helicopter Emergency Medical (HEM) Services typically attend OOHCAs, accounting for at least 10% of case numbers. [10] [11] [12] Successful resuscitation and return of spontaneous circulation (ROSC) occurs in 39-45% with survival to discharge rates of 6-12%. 11, 12 During the pandemic, HEMs teams continued to support NHS ambulance trusts with prehospital critical care provision. This observational study aimed to establish if there was a difference between OOHCAs attended by one HEM Service during the first UK national lockdown (23rd March-23rd June 2020) with the same time the previous calendar year (23rd March-23rd June 2019). This retrospective observational single centre study (Essex & Herts Air Ambulance) aimed to quantify (and compare) the number of OOHCAs within the operational area (Essex & Hertfordshire; population approximately 2.9 million) between the national lockdown period and the same period during the previous year. HEMs teams are dispatched when certain predetermined criteria are satisfied (immediate dispatch), following '999' call interrogation by a critical care paramedic or at the request of the attending medical team on-scene. Immediate dispatch for criteria includes traumatic cardiac arrest. There was no formal alteration of any dispatch criteria between the two time periods. The HEMs team carries a Lucas 3™ for automated chest compressions. The computerised record system at Essex & Herts Air Ambulance (HEMSbase2.0) was interrogated to extract anonymised OOHCA data for the two time periods in question (23 rd March-23 rd June 2020 c.f. 23 rd March-23 rd June 2019) Data relating to case demographics, aetiology, initial presenting cardiac rhythm, and outcome were all recorded. All OOHCA patients were included, irrespective of cause or outcome. Local research policies were satisfied; ethical approval was not required. 13 Attending clinicians attributed the aetiology of the OOHCA documenting this on the HEMSbase system, based on patient history and presenting symptoms. If post-mortem data was available this information was used to determine the aetiology. COVID-19 status for a patient was determined by the history on scene due to the lack of community testing 4 ; this was by confirming on scene that the patient was currently self-isolating, had a confirmed COVID-19 contact, or had reported classical symptoms and signs in the preceding days (cough/fever/shortness of breath/anosmia). When the cause of death was attributed to COVID-19 this was due to pneumonia or Acute Respiratory Distress Syndrome, rather than any other related disease; if the patient was COVID-19 positive but had an alternative cause of their OOHCA this was documented. This correlates with advice given to medical practitioners documenting causes of death during the pandemic where COVID-19 could be written as the cause of death if "before death the patient had symptoms typical of COVID-19 infection, but the test result has not been received." 14 In addition, anonymised data from the East of England Ambulance Service NHS Trust provided overall OOHCA case numbers for the East of England and patient outcome (survival to discharge/death-on-scene) information for those attended by the HEM service. Data was analysed using Microsoft Excel and SPSS statistics (version 26). A Shapiro-Wilk test was performed for normality on continuous values. Mean (if Gaussian) and median values (if non-Gaussian) were calculated as appropriate; Mann-Whitney U tests and Χ 2 were used to compare the datasets; a p-value <0.05 was considered statistically significant. The STROBE checklist was followed. 15 During this time, the HEM service ran until 10pm every day, except a Friday and Saturday whereby it ran until 2am. The East of England Ambulance Service recorded 912 OOHCA's for the whole East of England region, 16% of which were attended by EHAAT. In comparison during the lockdown period of 23 rd March 2020 to 23 rd June 2020 there were 539 activations of the HEMS service, of which 181 were for OOHCAs (34%). During this time frame there were a total of 956 OOHCAs calls for the whole East of England Ambulance Service region, with an activation rate of 19% for EHAAT. Data are summarised in Table 1 . There were 11 paediatric patients during the pandemic versus three in the reference time frame (an immediate dispatch criterion). The patients that were not intubated on scene received a supraglottic airway device. The breakdown of the causes of OOHCA can be seen in Table 2 . Self-harm refers to OOHCA secondary to either hanging, overdose or jumping from height. There was no statistically significant difference between the types of OOHCAs in the non-pandemic vs pandemic time frame (Χ 2 =5.0, p=0.17) but there was a statistically significant difference between the sub-classifications of medical OOHCA (Χ 2 =58.5, p<0.01). In 2020, 2 patients had symptoms consistent with COVID-19 within the previous two weeks, but their OOHCA was attributed to a myocardial infarction. Figure 1 shows the initial rhythm on arrival of the first emergency medical team; one patient was initially in sinus rhythm on arrival of the first medical responders but then experienced a cardiac arrest whilst the first responder was present. There was a statistically significant difference between the non-pandemic and pandemic groups with 52% presenting in a shockable rhythm in 2019 (ventricular fibrillation or pulseless ventricular tachycardia) versus only 32% in 2020 (Χ 2 =8.9, p<0.01). Figure 2 compares the destinations of the patients attended to by the HEMS team between the nonpandemic and pandemic time periods; there was no statistically significant difference (Χ 2 =6.2, p=0. 19) . Of the suspected COVID-19 OOHCAs during the pandemic, 59% of patients died on scene versus 43% of all other medical causes of OOHCAs during the same period. Of the patients whose death was attributed as COVID-19 the median age was 55, with 7 out of 16 being female. In 2019, of the 106 OOHCAs attended by EHAAT 11 patients (10.4%) are known to have survived to hospital discharge; 65% of patients died either at scene or in hospital (data missing/unavailable for 23 patients; 3 transferred alive to another hospital but outcome unknown). In comparison during the 2020 lockdown, 16 survived to discharge (13.2%); 80% died on scene or in hospital (data missing for 5 patients; 2 transferred alive to another hospital but outcome unknown). There was no statistically significant difference between the outcomes at discharge (Χ 2 =0.70, p=0.71). This study demonstrates statistically significant differences in patient demographics, aetiology of medical OOHCAs and initial presenting rhythm for all OOHCAs attended by one UK HEM service during the COVID-19 initial United Kingdom (UK) lockdown relative to a control period the previous year. Whilst it is recognised that a HEM service is likely to attend a relatively "self-selected" proportion of OOHCAs, it is interesting that this has changed during the pandemic. Some of the differences, such as the increased proportion of OOHCAs in women, are reflected in similar studies in the wider ambulance service, both within the UK and internationally, [6] [7] [8] [9] 16 but there are also some findings that are likely to be unique to HEM services, such as the lower median age seen during the pandemic by the HEM service. During the initial lockdown of the UK due to COVID-19 Essex & Herts Air Ambulance were activated to an increased number of OOHCAs (33% vs 26%) despite an overall decrease in HEMS activations during the same time period, reflecting similar trends identified by first responders both nationally and internationally. [6] [7] [8] [9] 16 Both figures represent a significantly higher activation percentage for OOHCAs than other similar HEM services within the UK (11% for Kent Surrey Sussex Air Ambulance). 11 In comparison with other studies the median age of the patients showed a statistically significant decrease during the pandemic. [6] [7] [8] [9] The median age was also significantly lower than that seen in hospital. 17 Of note, in a previous study of all OOHCAs attended by the East of England Ambulance Service NHS Trust their median age was 74, a contrast to the median age of 59 years in the 2019 non-pandemic time frame in this study. 18 This may be because HEMS dispatch criteria results in more activations for younger patients, because they are more likely to present in shockable rhythms or have witnessed arrests, achieve ROSC, and are therefore more likely to have positive outcomes; survival to hospital in the whole East of England Ambulance Service NHS Trust has been shown to be 27.6% versus 45.0% for those attended to by the corresponding HEM service teams. 12, 18 Therefore, during the COVID-19 pandemic, with the overall increase in OOHCAs it may be that dispatch focussed on patient groups deemed to have reversible pathology and therefore the greatest chance of survival. There may have been a shift in the interrogation technique of the critical care paramedics due to the sheer volume of OOHCAs during this period, without this being an explicit or formal change. In keeping with a similar study, this study also shows an increase in the percentage of females with OOHCA attended during the pandemic (30% vs 16%). 9 Within hospital one study identified a similar percentage of COVID-19 related cardiac arrests for females (34.7%). 17 Of the 16 patients who died on scene from suspected COVID-19, seven of them were female. Ordinarily there is a male predominance in OOHCAs so the increase in females attended is interesting. 11, 12, 18 The exact aetiology causing the COVID-19 related OOHCAs is still not fully understood, but an in-hospital study suggests that non-cardiac causes may be a greater influence. 17 It has been hypothesised that a hyper-inflammatory state may result in the development of tachyarrhythmias; it is unclear if this process is influenced by gender. 19 The pathophysiology attributed to this requires additional investigation. There may also have been more witnessed cardiac arrests in females, resulting in a HEMs dispatch, as family members may have been at home as a consequence of home schooling or childcare. During the pandemic, other ambulance services found the time until the first emergency responder was on scene increased. 9 The current study also found a notable increase in the average time to activation for the HEMS team for OOHCAs during the pandemic (almost double the median time in the reference time frame). Many of the OOHCAs attended by HEMS teams follow ambulance crew requests, for example if it is an ongoing shockable rhythm or there is a fragile return of spontaneous circulation. If it takes longer for the initial ambulance crew to reach the scene then this is likely to increase the time to HEMS dispatch. Increasing demand and finite resources may have the influenced the dispatch threshold of the critical care paramedic. Despite the lockdown, the HEMS team continued to attend traumatic cardiac arrests and cardiac arrests secondary to intentional self-harm, although there was no significant difference in the proportion of these cases attended relative to 2019. The number of traumatic cardiac arrests was very similar in the two time periods; this is likely to be multifactorial but possible explanations include higher speed road traffic collisions due to generally quieter roads. More intubations were performed pre-pandemic (61.3% vs 46.2%), perhaps because more patients achieved a ROSC necessitating a rapid sequence induction or because there was less desire to perform aerosol generating procedures during the pandemic. When medical cardiac arrests are classified by aetiology a statistically significant trend is identified. During the pandemic, it was noted internationally that there was a decrease in hospitalisation due to acute myocardial ischaemia. 20, 21 Only 16% of patients were taken for Percutaneous Coronary Intervention (PCI) centre during the pandemic lockdown compared to 30% in the non-pandemic; this is in keeping with a study in England that showed between February and May 2020 the rates of invasive coronary angiography were significantly lower than the same time period in 2019 among OOHCA patients. 22 30% of OOHCAs in the pandemic were in patients with suspected COVID-19; there may also have been additional COVID-19 patients that were not formally diagnosed in the pulmonary embolus, arrhythmia and/or myocardial ischemia group due to the limited availability of testing in the community initially. 4, 23 The on-scene mortality rate in the COVID-19 group was high at 59%, compared to 43% for all other medical OOHCAs for the same time period. This correlates with the higher on-scene mortality observed in other studies, although compared with London overall, it is not as high (59.0% versus 70.3%). 6, 9, 16 In regard to discharge from hospital, 13.2% of all OOHCA patients attended by HEMS were discharged alive from hospital during the lockdown. An initial non-shockable rhythm (PEA or asystole) was more frequently identified during the pandemic, correlating with similar studies in both a pre-hospital and in-hospital setting. 6, 8, 9, 17 In non-pandemic times, the majority of OOHCAs are shockable rhythms. 11 Non shockable rhythms in non-viable younger patients may result in increased crew requests to support complex withdrawal decision making. It should also be recognised that COVID-19 has taken its toll on the well-being of healthcare workers, and assistance in breaking bad news to families may be a valuable contribution from a HEMS team. 24 This may have resulted in a subtle change in crew requests for HEMS teams. The findings of this single service study may not be homogenous throughout UK HEMS services. However, it compliments data previously published for the same geographical areas and incorporates a comprehensive dataset. 12, 18 It is also recognised that there may have been some trends that had developed in the pre-COVID lockdown that continued in to the COVID lockdown, which were not accounted for and may cause a small amount of bias in the results; it is hoped that by choosing the same period of the year to analyse and with no significant change in dispatch criteria in that time period this impact is likely to be minimal. The precise cause of OOCHA may be indeterminate, particularly when the patient died on scene. This study identifies the most likely cause of the arrest based on the expert clinicians' detailed note keeping. Capacity to test for COVID-19 in the community was initially very limited. 4 The diagnosis of COVID-19 was therefore made by the healthcare practitioners attending "to the best of their knowledge and belief", as per the guidance for detailing cause of death during the pandemic. 14 This included a strong clinical suspicion of COVID-19 based on classical symptoms or direct COVID-19 contacts. Any late updates from the hospital teams following the OOHCAs were also recorded and used to help code the cause of arrest. There are likely to have been OOHCA causes that were misdiagnosed, including mis-diagnosed COVID-19; however, it is unlikely to have caused a significant effect on the results. Regarding discharge follow-up, data is missing for 22% of the 2019 data versus only 4% of the 2020 data. This lack of data may have resulted in a loss in statistical significance. This study also covers only the initial United Kingdom lockdown. Since June 2020 there have been a variety of other restrictions implemented, including two further full lockdowns, where testing was much more freely available. 4 With higher daily death rates in the United Kingdom in January 2021, research will be required to see whether the findings of this study are replicated during these additional lockdowns and throughout the country, and whether vaccination is now seen to be influencing outcomes. During the initial COVID-19 UK-wide lockdown, OOHCA characteristics altered for one HEM service with statistically significant differences in demographics, cause of medical cardiac arrest and initial presenting rhythm. In patients with suspected COVID-19 there were high mortality rates. A lower percentage of patients were taken for PCI when compared to pre-lockdown. With the increased demand on the wider ambulance services, changes to dispatch for the HEM service are likely to have occurred despite no explicit alteration. The HEM service is also likely to have offered additional support for ambulance crews in the less traditional roles of a HEM service, such as breaking bad news in young medical OOHCAs. With additional UK lockdowns and wider testing availability since the initial March 2020 lockdown, work is needed to explore if these trends continue and for consideration of how a HEM service can continue to support the wider ambulance service in future lockdowns or pandemics. Novel coronavirus disease (Covid-19): The first two patients in the UK with person to person transmission Strict new curbs on life in UK announced by PM, 2020 (Accessed 7 th The Health Foundation. 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The Covid-19 Pandemic and the Incidence of Acute Myocardial Infarction Reduction of hospitalizations for myocardial infarction in Italy in the COVID-19 era Pandemic on the Incidence and Management of Out-of-Hospital Cardiac Arrest in Patients Presenting With Acute Myocardial Infarction in England Cardiovascular Considerations for Patients, Health Care Workers, and Health Systems During the COVID-19 Pandemic Mental health problems faced by healthcare workers due to the COVID-19 pandemic-A review Sarah Morton: conceptualization, methodology, formal analysis, writing (original draft and review); Jonathan Dawson; methodology, writing (original draft and review and editing); Sarah McLachlan: methodology, formal analysis, writing (original draft and review and editing); William McGuiness: conceptualization, writing (review and editing) and supervision.