AED use unchanged with smartphone-dispatched responders to out-of-hospital cardiac arrest
Smartphone dispatch of volunteer responders for out-of-hospital cardiac arrest researchers conferred a small but not significant increase in automated external defibrillator attachment, researchers reported.
“We do not interpret the lack of statistical differences between treatment groups to reflect the fact that the volunteer responder system does not have an effect. Instead, we conclude that the control group grew strong as a result of methodological issues,” Ellinor Berglund, RN, PhD, of the department of clinical science and education, Södersjukhuset, Centre for Resuscitation Science at the Karolinska Institutet in Stockholm, and colleagues wrote. “Therefore, our overall conclusion is that the volunteer responder system contributes to an increase in the overall use of AEDs and bystander CPR and may represent an important complement to the efforts of standard [emergency medical services] and first responders.”
Design of the SAMBA trial
SAMBA was a phase 1, community-based, randomized trial that was conducted in the Swedish regions of Stockholm and Västra Götaland to test Heartrunner, a smartphone app developed for map-aided dispatch of CPR-trained volunteer responders. The volunteer responder system was integrated with a national register of AEDs. A total of 3,123 AEDs and 24,493 volunteer responders were registered in Stockholm and 3,195 devices and 19,117 volunteers were registered in Västra Götaland.
When an out-of-hospital cardiac arrest is suspected, the volunteer responder system locates a maximum of 30 volunteer responders within a 1.3 km radius of the suspected out-of-hospital cardiac arrest and the volunteers are requested via smartphone app to accept or decline the alert. Ambulances and on-duty first responders were dispatched simultaneously.
The volunteer responders then received map-aided directions via the app to the location of the suspected out-of-hospital cardiac arrest. Volunteers assigned to the intervention arm of the SAMBA trial also received information about the nearest AEDs while the control arm did not.
The primary outcome was overall bystander AED attachment, including those attached by the volunteer responders and volunteers not using the smartphone app.
Results of smartphone activated volunteer responders
Between December 2018 and January 2020, volunteer responders were activated for 947 patients with out-of-hospital cardiac arrest. AED attachment occurred in 13.2% of the intervention arm compared with 9.5% of the control arm (difference, 3.8 percentage points; 95% CI, –0.3 to 7.9; P = .08), the majority of which were used by lay volunteers not using the app. Volunteer responders attached 38% of all AEDs; provided 45% of all defibrillations; and provided 43% of all CPR, according to the study.
Researchers reported there was no significant differences in secondary outcomes including all bystander CPR and all bystander defibrillations between volunteers assigned to the interventions compared with the control arm.
Among the volunteers who used app, crossover during response to out-of-hospital cardiac arrest was 11% and compliance to instructions from the app was 31%.
“The reasons for crossover could be several, one being that an owner of an AED, or a volunteer responder close to one, will bring it, regardless of the instructions they received,” the researchers wrote. “Low compliance to instructions could also be explained by longer distances to collect the nearest AED, as reported in a previous study.”
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