Mobile phone-based alerting of CPR-trained volunteers simultaneously with the ambulance can reduce the resuscitation-free interval and improve outcome after out-of-hospital cardiac arrest: A German, population-based cohort study

Aim: To test the hypothesis that simultaneous mobile phone-based alerting of CPR-trained volunteers (Mobile-Rescuers) with Emergency Medical Service (EMS) teams leads to better outcomes in out-of-hospital cardiac arrest (OHCA) victims than EMS alerting alone. Methods: The outcomes of 730 OHCA patients were retrospectively analysed, depending on who initiated CPR: Mobile-Rescuer-initiated-CPR (n = 94), EMS-initiated-CPR (n = 359), lay bystander-initiated-CPR (n = 277). An adjusted analysis of the intervention and their main outcomes (emergency response time, return of spontaneous circulation, hospital discharge rate, neurological outcomes) was performed (Propensity Score Method with patient matching). Results: Recruited and trained Mobile-Rescuers (n =740) arrived at the scene in 46% of all triggered alarms. There was a significant difference in response time between Mobile-Rescuers (4 min) and EMS teams (7 min), (p < 0.001). Compared to EMS-initiated-CPR, Mobile-Rescuer-initiated-CPR patients more frequently showed a return of spontaneous circulation, but statistical significance was narrowly missed (p= 0.056). The hospital discharge rate was significantly higher with the Mobile-Rescuer (18%) vs. EMS (7%), (p = 0.049). Good neurological outcomes (Cerebral Performance Categories Score 1 and 2) were seen in 11% of Mobile-Rescuer patients and 4% of EMS patients (p = 0.165). There were no significant differences compared with lay bystander-initiated-CPR. Conclusion: Simultaneous alerting of nearby CPR-trained volunteers complementary to professional EMS teams can reduce both the response time and resuscitation-free interval and might improve hospital discharge rate and neurological outcomes after OHCA.