Volunteer First Responders for Cardiac Arrest at Home

Graphical Abstract: The figure provides a short description of the study design and main findings.

During the past years, many communities have experienced an increase in bystander cardiopulmonary resuscitation (CPR), some also in early defibrillation, and, subsequently, an improvement in survival after out-of-hospital cardiac arrest (OHCA) has been reported. Despite the enormous increase in AED (automated external defibrillator) deployment seen in many communities, bystander defibrillation has either stagnated or primarily improved in public locations, whereas little or no progress has been observed for OHCAs occurring at home.^[1] In addition, few intervention studies have focused on reaching OHCA patients in residential settings, even though this is where the vast majority of OHCAs occur. In the landmark Public Access Defibrillation Trial from 2004 which showed bystander AED use increased survival, only 15% of all included areas were residential settings, and only one person with definite OHCA was resuscitated in a home setting.^[2] Similarly disappointing results were found in the large Home Automated External Defibrillator (HAT) Trial from 2008, where 7001 patients who were estimated to be at high risk of cardiac arrest were randomly assigned to receive either standard care or standard care with the addition of a home AED.^[3] The trial did not find an improved survival in the home AED (intervention) group. It is important to note that many of the patients who did have a cardiac arrest in the HAT trial suffered a cardiac arrest outside their homes, thus limiting the effect of the 'home AED' strategy.

Whereas the 'home AED' strategy provides the opportunity to treat those in the immediate household (on-site), placing AEDs outside people's homes in residential areas, particularly in combination with volunteer responder systems, provides the opportunity to treat many patients within a much larger radius of an AED. The latter strategy obviously requires numerous and substantial logistic efforts including (i) a system to identify and locate registered volunteer responders, (ii) deployment of a sufficient number of accessible AEDs, (iii) a system to locate accessible AEDs (AED network), (iv) software linkage to the Emergency Medical Services (EMS), including training dispatchers to activate the system in case of suspected OHCA, and (v) recruitment of a sufficient number of volunteer responders. This strategy is currently being implemented in several communities and is now recommended by the American Heart Association and the European Resuscitation Council, despite the low level of evidence available.^[4,5] One randomized clinical trial (RCT) has shown an increase in bystander CPR when dispatching volunteer responders,^[6] and few RCTs are being conducted to investigate the effect of activation volunteer responders on bystander defibrillation and survival. Observational studies have shown an association between activating volunteer responders, increased bystander defibrillation, and survival, but none of these has shown increased survival for home arrests.^[7]

In this issue of the European Heart Journal, Stieglis and colleagues report very promising findings from a pioneering, large, volunteer responder programme in the Netherlands, with a special focus on home arrests.^[8] The study aimed to investigate whether the implementation of a volunteer responder system in addition to standard EMS care improved survival for home OHCAs with ventricular fibrillation (VF) as the first recorded rhythm. In the case of suspected OHCA, EMS dispatchers were able to activate registered volunteer responders through text messages to either collect a nearby AED (two-thirds of all responders) or go straight to the scene to provide CPR (one-third of all responders). The programme was initiated in 2009 and subsequently introduced in all 26 included municipalities in North-Holland North in a pragmatic, non-randomized, stepped-wedge cluster design. The inclusion of municipalities (and thus change over from control to intervention) was determined by logistic factors such as reaching the pre-determined number of deployed AEDs and registered volunteer responders, and not determined by a strict protocol. By March 2013, all municipalities had been included, accounting for a catchment area of 615 435 inhabitants. The study included 785 OHCA patients with VF, 407 of which were in the pre-introduction cohort and 347 were in the post-introduction cohort. The main results were that volunteer responders with AEDs administered shocks to 8% and 16% of all patients with VF in public and residential settings, respectively. Further, an increase in survival was observed in home arrests [from 26% to 39%, adjusted relative risk (RR) 1.5, 95% confidence interval (CI) 1.03–2.0], whereas no changes were seen for public arrests (RR 0.9, 95% CI 0.7–1.02). The authors concluded that introducing volunteer responders dispatched by text message to retrieve an AED was associated with significantly reduced time to defibrillation, increased bystander CPR, and increased overall survival for OHCA patients in residences found in VF.

Though several volunteer responder programmes have found an association between activating volunteer responders and increased rates of bystander CPR and defibrillation,^[7] the study by Stieglis and colleagues is the first to show an association between the activation of volunteer responders and increased survival for OHCA (VF) patients at home. Importantly, in addition to indicating an increase in bystander defibrillation and survival, this study provides a practical framework for how this was achieved. The investigators should be congratulated for implementing a model system including strategic AED placement of publicly accessible AEDs in residential areas with linkage to EMS, high volunteer responder recruitment, EMS dispatch, and high-quality OHCA data (including AED data).

The potential of a volunteer responder programme depends on the number (density) of volunteer responders and the number (density) of AEDs, both of which can be quite challenging to achieve. This paper describes a unique setting with both. In the Netherlands, the volunteer responder programme had been implemented for many years, and at the end of the study period, 5735 text message responders (=932 responders per 100 000 inhabitants) had registered as a volunteer responder in the study region. This is a high, but certainly achievable, number when compared with the number of volunteer responders per capita in countries such as Denmark,^[9] Sweden,^[10] and the UK.^[11] The community in which this study took place should also be recognized for its pioneering and substantial efforts to improve bystander defibrillation with the implementation of a volunteer responder programme as well as deployment of publicly accessible AEDs. Previous data have suggested that the chance of bystander defibrillation is three-fold higher and survival doubled if the nearest AED is accessible vs. behind locked doors at the time of OHCA.^[12] In addition, a large proportion of AEDs is often placed inside buildings or premises not accessible after normal working hours or on weekends, severely limiting the chance of AED use.^[13] The municipal authorities in the study areas were willing to invest in AEDs for residential use, and local AED owners were willing to place AEDs outside their premises, leading to the high AED density and accessibility reported in the study and a cornerstone for the successful increase in bystander defibrillation in home arrests.

While the results presented in the current study are very encouraging, several limitations should be taken into consideration when interpreting the results. This is a non-randomized study and thus findings should be interpreted as associations and not causality. The pragmatic stepped-wedge cluster design carries a risk of temporal bias. In this case, the study took place over 4 years, which is not a negligible time frame. It is noteworthy that during the study period and independent of the current study's interventions, the national police introduced AEDs in all patrol cars in the Netherlands in June 2009. Even though statistical analyses were employed in an attempt to adjust for these factors, it is not possible to achieve the standard of a randomized trial. Further, the investigators had no information on which responders or the proportion of responders who reached the patient prior to EMS, and whether or how these responders engaged in resuscitation. However, information on bystander AED use was collected and AED data were extracted. While the current study used a text message system to activate volunteer responders, today several mobile application systems providing more detailed information are available, for instance the proportion of volunteer responders (i) within a given activation radius, (ii) accepting or declining an alarm, and (iii) who reach the patient. One study has reported that activating volunteer responders through mobile applications is more efficient than using text messages.^[14] However, the only randomized trial on activation of volunteer responders used a text message system.^[6]

The system described in the current study relies mainly on the activation of non-professional volunteers using AEDs deployed outdoors. While this approach seems to work well in Europe, Australia, and New Zealand, other communities may not find it attractive for reasons such as liability or theft. In the USA, volunteer responder systems primarily activate off-duty professionals for home OHCAs, and AEDs are mostly deployed in vehicles of professional first responders such as fire or police.^[15] Thus, activating volunteer responders with AEDs can be implemented in various models, the cornerstones being commitment from the local community and key decision-makers. Efforts to test these models in a randomized fashion should be prioritized as high-quality evidence is warranted.

Taken together, Stieglis and colleagues are the first to show a survival benefit associated with activating volunteer responders to OHCAs at home, and this study serves as an excellent example and inspiration for other communities striving to improve bystander interventions, particularly AED use for OHCAs at home.