Influence of smartphone-based first aid systems on the outcome of out-of-hospital cardiac arrest.

Background: This study aims to evaluate the impact of Smartphone-based-first responder-systems (SFRS) such as "Mobile Retter" on relevant clinical endpoints in out-of-hospital cardiac arrest (OHCA).

Methods: Rescue service data from the district of Guetersloh between 2013 and 2023 were categorized into four groups based on the initiator of cardiopulmonary resuscitation (CPR): lay bystanders with (LB-Tel) and without telephone guidance from the rescue service control center (LB-no-Tel), community first responders (CFR) and emergency medical services (EMS). The results were analyzed using a propensity score analysis with overlap weighting.

Results: Overall, 1,620 resuscitations (LB-Tel: N.=493(30.4%); LB-no-Tel: N.=341(21.0%); CFR: N.=187(11.5%); EMS: N.=599(37.0%)) were analyzed. Compared to EMS, the emergency response time (ERT) of CFR was significantly shorter (95%CI: -2.01- -0.89). Regarding achieving a return of spontaneous circulation (ROSC) and a good neurological outcome (OUT), there was no evidence of a difference between CFR and EMS (ROSC:odds ratio (OR):0.90;95%CI:0.56-1.45; OUT: OR:1.04;95%CI:0.42-2.54). However, when comparing CFR with LB-Tel showed a clinically relevant tendency for a favorable effect in relation to ROSC for CFR (ROSC: OR:1.17; 95%CI:0.72-1.92). In contrast, the group of CFR showed a lower chance of achieving a ROSC compared to LB-no-Tel (ROSC: OR:0.86;95%CI:0.51-1.46).

Conclusions: SFRS significantly reduce ERT compared to EMS, but our study was unable to provide evidence of a higher chance of ROSC or a good neurological outcome. To improve the outcome after OHCA, public training in resuscitation measures should be intensified, and the network of CFR should be expanded.