key: cord-0898582-pcff4ndx
authors: Scquizzato, Tommaso; Pallanch, Ottavia; Belletti, Alessandro; Frontera, Antonio; Cabrini, Luca; Zangrillo, Alberto; Landoni, Giovanni
title: Enhancing Citizens Response to Out-of-Hospital Cardiac Arrest: A Systematic Review of Mobile-Phone Systems to Alert Citizens as First Responders
date: 2020-05-11
journal: Resuscitation
DOI: 10.1016/j.resuscitation.2020.05.006
sha: 41a2be36208e8fbd596384a0ea4b028e95bc9d3d
doc_id: 898582
cord_uid: pcff4ndx

Abstract Introduction Involving laypersons in response to out-of-hospital cardiac arrest through mobile-phone technology is becoming widespread in numerous countries, and different solutions were developed. We performed a systematic review on the impact of alerting citizens as first responders and to provide an overview of different strategies and technologies used. Methods We searched electronic databases up to October 2019. Eligible studies described systems to alert citizens first responders to out-of-hospital cardiac arrest through text messages or apps. We analysed the implementation and performance of these systems and their impact on patients’ outcomes. Results We included 28 manuscripts describing 12 different systems. The first text message system was implemented in 2006 and the first app in 2010. First responders accepted to intervene in median (interquartile) 28.7% (27-29%) of alerts and reached the scene after 4.6 (4.4-5.5) minutes for performing CPR. First responders arrived before ambulance, started CPR and attached a defibrillator in 47% (34-58%), 24% (23-27%) and 9% (6-14%) of cases, respectively. Pooled analysis showed that first responders activation increased layperson-CPR rates (1463/2292 [63.8%] in the intervention group vs. 1094/1989 [55.0%] in the control group; OR=1.70; 95% CI, 1.11–2.60; p=0.01) and survival to hospital discharge or at 30 days (327/2273 [14.4%] vs. 184/1955 [9.4%]; OR=1.51; 95% CI, 1.24–1.84; p<0.001). Conclusions Alerting citizens as first responders in case of out-of-hospital cardiac arrest may reduce the intervention-free time and improve patients’ outcomes.

pm [23] , and two systems [19, 20] were active 24/7. The vast majority of systems accepted CPR 167 trained laypeople only ( Table 2 ) and none of the systems declared to pay first responders for their 168 service. 169

First responders located either within a prespecified activation radius from the OHCA location or 170 on the same city, community or neighbourhood of the OHCA were notified through a text message 171 or with the app. The systems calculated the distance between the current (or most recent) position of 172 first responders obtained through Global Positioning System (GPS) tracking or from a set of 173 registered addresses (e.g. work or home address) and the OHCA address provided by the caller. The 174 activation radius varied among systems from 150 meters [31] up to 5 kilometres [44] , mainly due to 175 the different characteristics of the area and the density of first responders. A complete overview of 176 the strategies adopted by the different systems is available in Table 2 . Remarkably, one system was 177 developed to progressively expand the radius during each alert until a prespecified number of first 178 responders was located and accepted to intervene [45] . In Switzerland, the activation radius was 179 dynamically adjusted based on the estimated time of arrival of the ambulance (the shorter the 180 estimated time of arrival, the smaller the activation radius). [19] For an optimal alert system, the 181 minimum density of first responders was found to be at least ten first responders per square 182 kilometre.

[40] 183 184 Alerting first responders: text messages versus smartphone apps (n=1) [27] . The characteristics of identified systems are summarized in Table 2 . 191 Compared to text messages, the use of a mobile app increased up to 70% the proportion of first 192 responders to be first on the scene with a reduction of the arrival time (3.5 minutes [2. 8- arrival before ambulance in these three strategies was respectively 58-69%, 59-100%, and 90-99%. 208

On median, a first responder reached the scene for performing CPR after 4.3 (4.1-4.9) minutes and 213 delivered an AED after 7.5 (6.7-8.4) minutes. First responders arrived before EMS in median 47% 214 (34-58%) of occasions, performed CPR in median 24% (23-27%) of cases and attached an AED in 215 9% (6-14%) of patients. Among those victims who had an AED positioned by the first responder, 216 the first rhythm registered was shockable in 35% (25-47%) of cases. (Table 3) 

In this comprehensive systematic review and meta-analysis, we investigated the impact of alerting 250 citizens acting as first responders in the immediate vicinity of an OHCA with a text message or a 251 smartphone app alert system. We found that implementing a system to alert first responders may 252 reduce the period of time without intervention before EMS arrival. In many cases, first responders 253 alerted through either text messages or mobile apps were able to timely reach the patient before 254 ambulance arrival, start CPR and attach an AED. Furthermore, our meta-analysis suggested that J o u r n a l P r e -p r o o f patients who suffer an OHCA and are treated by first responders are more likely to receive CPR 256 before ambulance arrival and survive to hospital discharge or at 30 days. However, the involvement 257 of first responders did not improve rates of ROSC. Only one before-and-after study [23] reported 258 survival to hospital discharge with good neurological outcome and found an improvement after the 259 implementation of the alert system. 260

It is well known that in case of OHCA, early CPR [46] and early defibrillation [47] improve 261 survival. Unfortunately, nowadays surviving OHCA is often left to chance (i.e. to the casual 262 presence of a bystander trained in CPR and willing to intervene) instead to a robust system with a 263 strong emphasis on immediate recognition of cardiac arrest, activation of the emergency response 264 system, early CPR and early defibrillation. Our review focused on a relatively novel technology that 265 is cheap, simple, and universally present: smartphones and dedicated apps to improve the response 266 to OHCA. 267

We found several differences in locating, alerting and managing first responders systems. (Table 2 ) 268

Choosing the right approach to implement a network of first responders may have a considerable 269 impact on the effectiveness of the system ( Figure 3) . First, the number of notified citizens and the 270 radius used to localize the nearest one are variable. This may reduce the proportion of OHCA in 271 which a first responder is able to timely reach the location, in particular in cases of a low density of 272 first responders or when they reach the scene by foot or by car. Second, not every system is active 273 and functioning 24/7: some of these are deactivated during the night and others alert first responders 274 only for OHCA occurring in public places. Third, directing first responders directly to the OHCA 275 site or only after collecting an AED may have implications for patients' outcomes and system 276 management. One study in Switzerland reported a significant reduction in time of CPR initiation J o u r n a l P r e -p r o o f timely reach the location and start CPR or if a high-quality bystander-CPR is already in progress. 280

Fourth, the majority of OHCAs occurs at home and privacy concerns may prevent alerting first 281 responders in these cases. Notably, the results of a survey conducted in North American showed 282 instead that citizens are comfortable to receive assistance in case of OHCA from first responders 283 also in a private location [42] . 284

In recent years, with the rapid growth in technology, smartphones and mobile apps have become an 285 essential part of our lives. Nowadays, first responder systems should be implemented on app-based 286 systems. Compared to text message systems, apps offer the advantage of continuously geolocate the 287 first responders with accuracy, real-time update of the details of the event, on-scene audio and video 288 streaming, displaying the position of nearby AEDs and directing the first responders either to the 289 OHCA location or to the nearest AED based on the estimated distance and time required. However, 290 an active internet connection is mandatory to offer these functionalities, and this should be 291 considered when implementing such systems in remote areas with inadequate network coverage. 292

Given the accuracy of app geolocation, such technology may also allow to dynamically adjust the 293 activation radius [29] to alert only the nearest and most competitive first responder compared to the 294 estimated time of arrival of ambulances. In a study carried out in Switzerland, the app-based system 295 was found to significantly reduce the time to initiation of CPR and to increase rates of survival 296 when compared to a text message system [19] . Interestingly, the fifth-generation (5G) wireless 297 network, thanks to its capability to process data at faster speeds, has the potential to further improve 298 these systems. Examples of 5G applications will include the transmission of high-quality and 299 latency-free video with augmented reality to help first responders who are on the scene of an 300 OHCA, drone-delivered AEDs and highly accurate and continuous geolocation without ruining 301 devices battery.

to trigger a cardiac arrest notification are all aspects that. Failure to obtain real-time GPS location 306 from apps, and seasonal variability can further worsen these first responder systems. Moreover, 307

considering that these apps rely on third-party devices with operating systems that could be 308 subjected to changes and updates, a close technological monitoring should be implemented to avoid 309 issues with the functioning of geolocation and alert system. The present study is the first systematic review to comprehensively identify the state-of-the-art on 320 the topic, provide information for further development of first responder systems and inform future 321 research. So far, our work represents the best evidence but has some limitations. First, we identified 322 only one RCT. Second, we limited our search to systems published and described in the literature 323 and thus this review may not provide a complete picture of all existing systems. Third, two out of 324 the three studies included in the quantitative analyses carried a serious risk of bias. Abstracts, 325 editorials and conference proceedings were included only in qualitative descriptions to provide a of first responder systems were not reported in the identified manuscripts except in one before-and-331 after study [23] thus limiting the understanding of benefits of such technologies. Also, the important 332 aspect of liability and safety of first responders was not covered in the identified articles: to protect 333 lay people who offer assistance during an emergency situation, a Good Samaritan law should be 334 implemented in every country. Furthermore, when interpreting our findings, the differences 335 between countries in the healthcare organization, EMS system organization and clinical practice 336 must be considered. The culture of action and education in resuscitation manoeuvres among the 337 population of each country also has a huge impact on the effectiveness of these systems. 338

Two ongoing RCTs will hopefully provide more insights on the role of first responders alerted in 339 response to OHCA. The Scandinavian AED and Mobile Bystander Activation Trial (SAMBA, 340

ClinicalTrials.gov NCT02992873) is randomizing first responders to reach the OHCA location 341 directly or only after collecting an AED. In both groups, at least one first responder will be alerted 342 to provide only CPR along with standard EMS care. In Denmark, the HeartRunner Trial 343 (ClinicalTrials.gov NCT03835403) is randomizing OHCAs to either activation of first responders 344 or not (standard EMS care) to assess 30-day survival. Given the complex situations in which first 345 responders are involved, this study will also evaluate the physical or psychological risks of 346 activated first responders. Moreover, investigating the impact on long term outcomes and working 347 towards the standardization of reporting data about first responders systems is highly emphasized. 348 suggest that first responders may be able to timely reach the OHCA before ambulance arrival and 353 reduce the intervention-free time by starting CPR and attaching an AED. These advantages could 354 lead to an improvement in rates of CPR performed before ambulance arrival and survival to hospital 355 discharge or at 30 days. We identified several differences among first responder systems and found 356 that the right choice of strategy and technological implementation play a critical role in their 357 effectiveness. However, RCTs are needed to provide conclusive data. n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a Good Samaritan [31] n/a n/a n/a n/a n/a n/a n/a PulsePoint Respond

[33, 42] 23% n/a n/a 25% n/a n/a n/a 29.3% n/a n/a n/a n/a n/a n/a DAE RespondER [44] n/a 19% ~ 2 min b in 25% of cases n/a n/a n/a n/a a Name of the app/system not found. 615 b Direct to OHCA location for performing CPR 616 c After collecting an AED 617 ROSC = Return of spontaneous circulation, CPC = Cerebral Performance Category, OHCA = Out-618 of-hospital cardiac arrest, CPR = Cardiopulmonary Resuscitation 619

Global incidences of out-of-hospital 367 cardiac arrest and survival rates: Systematic review of 67 prospective studies

Incidence of EMS-treated out-of-hospital 370 cardiac arrest in Europe

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Collaboration's tool for assessing risk of bias in randomised trials

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Lidocaine, or Placebo in Out-of-Hospital Cardiac Arrest

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Food-riders may improve the chain of survival in out-of-526 hospital cardiac arrests by delivering CPR and AEDs

Smartphone software update could 529 potentially affect the efficiency of lay first-responders networks in out-of-hospital cardiac arrests

None. 364