In out-of-hospital cardiac arrest (OHCA) patients with extracorporeal cardiopulmonary resuscitation (ECPR), the association between low-flow time, the duration between the initiation of conventional cardiopulmonary resuscitation and the establishment of ECPR, and outcomes has not been clearly determined.

This was a secondary analysis of the retrospective multicenter registry in Japan. This study registered patients ≥18 years old who were admitted to the emergency department for OHCA and underwent ECPR between January, 2013 and December, 2018. Low-flow time was defined as the time from initiation of conventional cardiopulmonary resuscitation to the establishment of ECPR, and patients were categorized into two groups according to the visualized association of the restricted cubic spline curve. The primary outcome was survival discharge. Cubic spline analyses and multivariable logistic regression analyses were performed to assess the nonlinear associations between low-flow time and outcomes.

A total of 1,524 patients were included. The median age was 60 years, and the median low-flow time was 52 (42‐53) mins. The overall survival at hospital discharge and favorable neurological outcomes were 27.8% and 14.2%, respectively. The cubic spline analysis showed a decreased trend of survival discharge rates and favorable neurological outcomes with shorter low-flow time between 20 and 60 mins, with little change between the following 60 and 80 mins. The multivariable logistic regression analyses showed that patients with long low-flow time (>40 mins) compared to those with short low-flow time (0‐40 mins) had significantly worse survival (adjusted odds ratio 0.42; 95% confidence intervals, 0.31-0.57) and neurological outcomes (0.65; 0.45-0.95, respectively).

The survival discharge and neurological outcomes of patients with low-flow time shorter than 40 min are better than those of patients with longer low-flow time.