Extracorporeal cardiopulmonary resuscitation (ECPR) is increasingly used for refractory paediatric in-hospital cardiac arrest (IHCA). Although rapid initiation of extracorporeal life support (ECLS) is widely considered critical, the relative contributions of cannulation timing and early physiologic recovery to survival outcomes remain incompletely defined.

We conducted a retrospective cohort study of paediatric patients who underwent ECPR for IHCA at a tertiary cardiac centre between 2010 and 2022. The primary exposure was the interval from cardiac arrest to initiation of ECLS flow. Outcomes included survival to ECLS decannulation and survival to hospital discharge. Multivariable logistic regression was used to evaluate associations between clinical variables, metabolic markers, and outcomes.

Seventy-nine patients were included. Median time to ECLS flow was 35 min (interquartile range 22–50). Survival to ECLS decannulation and to hospital discharge were 80.8% and 52.1%, respectively. Shorter time to ECLS flow was independently associated with survival to ECLS decannulation (adjusted odds ratio 0.96 per minute increase in time to ECLS flow; 95% confidence interval 0.93–0.99; p = 0.008) but not with survival to hospital discharge. Higher initial lactate (aOR 0.85; 95% CI 0.72–0.98), higher 4-h lactate (aOR 0.81; 95% CI 0.67–0.97), and lower initial pH (aOR 1.34 per 0.1-unit decrease; 95% CI 1.04–1.86) were independently associated with reduced survival to decannulation. Four-hour lactate was independently associated with survival to hospital discharge (adjusted odds ratio 0.78; 95% confidence interval 0.66–0.94; p = 0.007).

In paediatric IHCA treated with ECPR, early metabolic derangement and impaired metabolic recovery after cannulation appear to reflect the severity of post-arrest physiology and are associated with survival outcomes. These findings suggest that, in addition to the rapid deployment of ECPR, early physiologic recovery following initiation of extracorporeal support may be an important determinant of meaningful survival.