Out-of-hospital cardiac arrest survival when CPR is initiated by first responders

Abstract

Background: In most patients with out-of-hospital cardiac arrest (OHCA), cardiopulmonary resuscitation (CPR) is initiated by first responders (non-transporting firefighters or police) or emergency medical service (EMS) personnel. Whether survival outcomes differ when CPR is initiated by first responders vs. EMS is unclear.

Methods: Within the CARES registry, we identified 162,896 adult patients with a non-traumatic OHCA in whom CPR was initiated by first responders or EMS during 2013-2021. Using multivariable hierarchical logistic regression to adjust for demographics, cardiac arrest characteristics and time to first CPR, we compared rates of survival to hospital admission and to discharge in patients with CPR initiated by first responders and EMS.

Results: CPR was initiated by first responders in 70,889 (43.5%) and by EMS in 92,007 (56.5%) patients. Time to first CPR was shorter when first responders initiated CPR (median: 8.0 [5.0-13.0] vs. 10.0 minutes [IQR: 6.0-14.0]; standardized difference 16.1%). The likelihood of survival to hospital admission was similar when CPR was initiated by first responders (27.1% [first responders] vs. 26.8% [EMS]; adjusted OR: 0.98 [0.96, 1.01], P = 0.15) whereas survival rates to discharge were higher with CPR initiated by first responders (9.4% [first responders] vs. 7.7% [EMS]; adjusted OR: 1.17 [1.02, 1.21], P < 0.001). After adjustment for time to first CPR, rates of survival to discharge were similar between the first responder and EMS groups (adjusted OR: 1.04 [1.00-1.08]; P = 0.07).

Conclusions: CPR initiated by first responders for OHCA is associated with higher overall survival rates and higher survival was largely mediated by earlier response times.

Keywords: Emergency medical services; First responder; Out-of-hospital cardiac arrest.