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. 2023 Jan 1;8(1):81-88.
doi: 10.1001/jamacardio.2022.4362.

Effect of Smartphone Dispatch of Volunteer Responders on Automated External Defibrillators and Out-of-Hospital Cardiac Arrests: The SAMBA Randomized Clinical Trial

Ellinor Berglund  1 , Jacob Hollenberg  1 , Martin Jonsson  1 , Leif Svensson  2 , Andreas Claesson  1 , Anette Nord  1 , Per Nordberg  1 , Sune Forsberg  1 , Mårten Rosenqvist  3 , Peter Lundgren  4   5   6 , Åsa Högstedt  4   5 , Gabriel Riva  1 , Mattias Ringh  1
Affiliations

Effect of Smartphone Dispatch of Volunteer Responders on Automated External Defibrillators and Out-of-Hospital Cardiac Arrests: The SAMBA Randomized Clinical Trial

Ellinor Berglund et al. JAMA Cardiol. .

Abstract

Importance: Smartphone dispatch of volunteer responders to nearby out-of-hospital cardiac arrests (OHCAs) has emerged in several emergency medical services, but no randomized clinical trials have evaluated the effect on bystander use of automated external defibrillators (AEDs).

Objective: To evaluate if bystander AED use could be increased by smartphone-aided dispatch of lay volunteer responders with instructions to collect nearby AEDs compared with instructions to go directly to patients with OHCAs to start cardiopulmonary resuscitation (CPR).

Design, setting, and participants: This randomized clinical trial assessed a system for smartphone dispatch of volunteer responders to individuals experiencing OHCAs that was triggered at emergency dispatch centers in response to suspected OHCAs and randomized 1:1. The study was conducted in 2 main Swedish regions: Stockholm and Västra Götaland between December 2018 and January 2020. At study start, there were 3123 AEDs in Stockholm and 3195 in Västra Götaland and 24 493 volunteer responders in Stockholm and 19 117 in Västra Götaland. All OHCAs in which the volunteer responder system was activated by dispatchers were included. Excluded were patients with no OHCAs, those with OHCAs not treated by the emergency medical services, and those with OHCAs witnessed by the emergency medical services.

Interventions: Volunteer responders were alerted through the volunteer responder system smartphone application and received map-aided instructions to retrieve nearest available public AEDs on their way to the OHCAs. The control arm included volunteer responders who were instructed to go directly to the OHCAs to perform CPR.

Main outcomes and measures: Overall bystander AED attachment, including those attached by volunteer responders and lay volunteers who did not use the smartphone application.

Results: Volunteer responders were activated for 947 patients with OHCAs. Of those, 461 were randomized to the intervention group (median [IQR] age of patients, 73 [61-81] years; 295 male patients [65.3%]) and 486 were randomized to the control group (median [IQR] age of patients, 73 [63-82] years; 312 male patients [65.3%]). Primary outcome of AED attachment occurred in 61 patients (13.2%) in the intervention arm vs 46 patients (9.5%) in the control arm (difference, 3.8% [95% CI, -0.3% to 7.9%]; P = .08). The majority of AEDs were attached by lay volunteers who were not using the smartphone application (37 in intervention arm, 28 in control). There were no significant differences in secondary outcomes. Among the volunteer responders using the application, crossover was 11% and compliance to instructions was 31%. Volunteer responders attached 38% (41 of 107) of all AEDs and provided 45% (16 of 36) of all defibrillations and 43% (293 of 666) of all CPR.

Conclusions and relevance: In this study, smartphone dispatch of volunteer responders to OHCAs to retrieve nearby AEDs vs instructions to directly perform CPR did not significantly increase volunteer AED use. High baseline AED attachement rate and crossover may explain why the difference was not significant.

Trial registration: ClinicalTrials.gov Identifier: NCT02992873.

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Conflict of interest statement

Conflict of Interest Disclosures: Drs Hollenberg, Jonsson, Claesson, Rosenqvist, Ring reported grants from Swedish Heart and Lung foundation during the conduct of the study. Drs Hollenberg, Svensson, Claesson, Nordberg, Rosenqvist, and Ringh are shareholders of CAAR Holding AB. Dr Rosenqvist reported personal fees from Zenicor, Pfizer, and Roche and grants from Stockholm County outside the submitted work. No other disclosures were reported.

Figures

Figure 1.
Figure 1.. Allocated Patients With Suspected Out-of-Hospital Cardiac Arrest (OHCA)
Indexed as OHCAs indicates the dispatcher at the emergency dispatch center has assigned the call to be a suspected OHCA according to the medical index. EMS indicates emergency medical services.
Figure 2.
Figure 2.. Outcomes and Actions Performed by Bystanders and by Dispatched Volunteer Responders
Bystander cardiopulmonary resuscitation (CPR) (A), automated external defibrillator (AED) (B), and bystander defibrillation (C) outcomes are shown. Each square indicates 1 patient with out-of-hospital cardiac arrest. Volunteer responder actions are validated by online survey and a telephone interview.
Figure 3.
Figure 3.. Volunteer Responder Compliance
AED indicates automated external defibrillator; CPR, cardiopulmonary resuscitation; EMS/FR, emergency medical services and first responders (police, fire department).
See this image and copyright information in PMC

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