Dual dispatch and the importance of bystander CPR in out-of-hospital cardiac arrest

• Background and aim: Survival after out-of-hospital cardiac arrest (OHCA) remains low. In Sweden in 2016, of 5312 cases reported to the Swedish Register of Cardiopulmonary Resuscitation (SRCR), only 577 (11%) survived to 30-days. The overall objective of the present work was to explore prehospital measures to increase survival for persons suffering OHCA, with special focus on alternative resources such as early bystander cardiopulmonary resuscitation (ByCPR), and dispatch of emergency medical services (EMS) in parallel with first responders (FRs) equipped with defibrillators performing basic life support. Methods and results: Study I. A retrospective national register study covering 1990–2011 and including 30,381 witnessed OHCA. The primary aim was to evaluate the effect on survival if ByCPR was provided before arrival of EMS. 15,512 (51.1%) patients received ByCPR whereas 14,869 (48.9%) did not. Survival to 30-days was 10.5% in the ByCPR group vs. 4.0% in the no ByCPR group (p<0.001). Study II. A prospective national intervention study covering 2012–2014 and including 8698 OHCAs. In nine Swedish counties firefighters and/or police officers were trained in basic life support (BLS) and defibrillation and were dispatched at the same time as EMS in cases of suspected OHCA (n=3543). This group was compared with a propensity-matched control group from twelve other counties where EMS only were dispatched (n=5155). The final analytic sample consisted of 2786 matched pairs. The proportion of patients that survived to 30 days was 266/2786 (9.5%) in the intervention group vs. 214/2786 (7.7%) in the control group (conditional OR 1.27, 95% CI 1.05–1.54). Study III. A prospective intervention study including 7200 witnessed OHCAs from the cohort in Study II. The primary aim was to evaluate 30-day survival in relation to time to treatment by means of cardiopulmonary resuscitation (CPR) and defibrillation by EMS or FRs. The cases were investigated as regards time for EMS arrival (<8 minutes or >8 minutes), and if ByCPR was provided or not. In the former group survival was 378/2016 (19.1%) compared with 542/5160 (10.7%) in the latter group (p<0.001). Study IV. A qualitative interview study with 22 firefighters and police officers in Stockholm County participating in dual dispatch with EMS in cases of OHCA. In total 60 critical incidents (CIs) were identified concerning selfperceived OHCA situations. These where analyzed by using inductive content analysis. Three consecutive time sequences were found describing the cardiac arrest situation: Preparedness, Managing the scene, and The aftermath. The main findings were 1) Lack of information from the dispatch center caused frustration amongst first responders, 2) More thorough training was required in first aid and CPR, especially concerning rescue breaths. Education concerning psychological reactions amongst bystanders after an OHCA was requested, 3) Discussion after a mission with participating colleagues and superiors was deemed necessary, especially after tough cases. Conclusions: Early ByCPR initiated before arrival of EMS more than doubled 30-day survival in cases of OHCA.This finding was consistent among all prespecified subgroups analyzed. Implementation of a national dual dispatch system of EMS and first responders in cases of OHCA providing CPR and potentially defibrillation, is associated with a shortened response time, more patients admitted to hospital alive and a moderate but significant increase in 30- day survival. The combination of reduced response times of EMS and FRs to less than eight minutes in cases of witnessed OHCA, and early ByCPR initiated before their arrival, can substantially improve 30-day survival, especially in cases with a shockable heart rhythm. When introducing dual dispatch of FRs as a second tier in cases of OHCA, CPR and hands-on AED training must be repeated annually to maintain CPR skills. Education in psychological reactions amongst bystanders should also be addressed, and team assessment offered after mission is important to avoid occupational stress.

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