Unchanged use of the AED with responders dispatched by smartphone in the event of out-of-hospital cardiac arrest

Smartphone dispatch of volunteer responders for out-of-hospital cardiac arrest researchers conferred a small but nonsignificant increase in automated external defibrillator attachment, the researchers reported.

“We do not interpret the lack of statistical differences between the treatment groups to reflect that the voluntary responder system has no effect. Instead, we conclude that the control group did reinforced due to methodological problems”, Ellinor Berglund, RN, Ph.D., from the Department of Clinical and Educational Sciences, Södersjukhuset, Center for Resuscitation Sciences at 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 near-field CPR and may represent an important complement to standard efforts. [emergency medical services] and first responders.

SAMBA trial design

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 card-assisted dispatch of trained CPR volunteer responders. The voluntary intervention system has been incorporated into a national AED registry. 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 up to 30 volunteer responders within a 1.3 km radius of the suspected out-of-hospital cardiac arrest and volunteers are invited via the app to smartphone to accept or decline the alert. Ambulances and first responders on duty were dispatched simultaneously.

The volunteer responders were then given map directions via the app to the location of the suspected cardiac arrest outside of the hospital. Volunteers assigned to the intervention arm of the SAMBA trial also received information about the closest AEDs, while the control arm did not.

The primary outcome was overall viewer attachment to the DEA, including those attached by volunteer responders and volunteers not using the smartphone app.

Smartphone-enabled volunteer responder results

Between December 2018 and January 2020, volunteer responders were activated for 947 patients who suffered out-of-hospital cardiac arrest. AED attachment occurred in 13.2% of the intervention arm versus 9.5% of the control arm (difference, 3.8 percentage points; 95% CI, -0.3 to 7.9 ; P = 0.08), the majority of which was 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.

The researchers reported that there were no significant differences in secondary outcomes, including all CPRs and all bystander defibrillations between volunteers assigned to the interventions compared to the control group.

Among the volunteers who used the app, crossover when responding to out-of-hospital cardiac arrest was 11% and adherence to app instructions was 31%.

“The reasons for crossbreeding could be multiple, one being that an owner of an AED, or a volunteer responder close to one, will bring it, regardless of the instructions they received,” wrote the researchers. “Low instruction compliance could also be explained by longer distances to retrieve the nearest AED, as reported in a previous study.”