Relationship Between the Duration of Cardiopulmonary Resuscitation and Favorable Neurological Outcomes After Out‐of‐Hospital Cardiac Arrest: A Prospective, Nationwide, Population‐Based Cohort Study

BACKGROUND: The determination of appropriate duration of in‐the‐field cardiopulmonary resuscitation (CPR) for out‐of‐hospital cardiac arrest (OHCA) patients is one of the biggest challenges for emergency medical service providers and clinicians. The appropriate CPR duration before termination of resuscitation remains unclear and may differ based on initial rhythm. We aimed to determine the relationship between CPR duration and post‐OHCA outcomes. METHODS AND RESULTS: We analyzed the records of 17 238 OHCA patients (age ≥18 years) who achieved prehospital return of spontaneous circulation. Data were prospectively recorded in a nationwide, Japanese database between 2011 and 2012. The time from CPR initiation to prehospital return of spontaneous circulation (CPR duration) was calculated. The primary end point was 1‐month survival with favorable neurological outcomes (Cerebral Performance Category [CPC] scale; CPC 1–2). The 1‐month CPC 1–2 rate was 21.8% (n=3771). CPR duration was inversely associated with 1‐month CPC 1–2 (adjusted unit odds ratio: 0.95, 95% CI: 0.94–0.95). Among all patients, a cumulative proportion of >99% of 1‐month CPC 1–2 was achieved with a CPR duration of 35 minutes. When sorted by the initial rhythm, the CPR duration producing more than 99% of survivors with CPC 1–2 was 35 minutes for shockable rhythms and pulseless electrical activity, and 42 minutes for asystole. CONCLUSIONS: CPR duration was independently and inversely associated with favorable 1‐month neurological outcomes. The critical prehospital CPR duration for OHCA was 35 minutes in patients with initial shockable rhythms and pulseless electrical activity, and 42 minutes in those with initial asystole.