Dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) program was implemented to increase bystander CPR and improve outcomes of out-of-hospital cardiac arrest (OHCA) patients. To understand the pathway of how DA-CPR improves outcomes of OHCA, this study aimed to evaluate the effect of DA-CPR on early defibrillation and early return-of-spontaneous circulation (ROSC) with survival.
A population-based observational study was conducted for all emergency medical services-treated adult OHCAs with cardiac etiology between 2013 and 2016 using national OHCA registry. Cases without witness, occurred in hospital, witnessed by EMS provider, and defibrillated by layperson were excluded. Exposure was bystander CPR status: no bystander CPR (No BCPR), bystander CPR without dispatcher-assistance (NDA-BCPR), and bystander CPR with dispatcher assistance (DA-BCPR). The observation time was set to a maximum of 90 mins for survival analysis. The primary outcome was ROSC leads to survival discharge within 90 mins (ROSC with survival). The secondary outcome was first defibrillation within 90 mins (defibrillation). The multivariable Cox proportional hazard analysis was performed to calculate adjusted hazard ratios (AHRs) according to bystander CPR status adjusting for potential confounders.
Of 25,450 eligible OHCAs, NDA-BCPR provided for 3,193 cases (12.5%) and DA-BCPR provided for 12,154 cases (47.8%). ROSC with survival was observed in 13.2% in NDA-BCPR and 12.0% in DA-BCPR Compared with No BCPR. Both NDA-BCPR and DA-BCPR were associated with 44% and 55% increase in early ROSC with survival (AHRs, 95% CIs; 1.44, 1.27 to 1.63 for NDA-BCPR and 1.55, 1.41 to 1.69 for DA-BCPR). DA-BCPR was also associated with early defibrillation compared with No-BCPR accounting for ROSC as a competing risk (AHR, 95% CIs; 1.16, 1.12 to 1.21).
Compared with no bystander CPR provided, both bystander CPR with or without dispatcher assistance were associated with early defibrillation and early ROSC lead to survival in witnessed OHCA patients.