Neurological outcomes and survival after prehospital ECPR: the impact of low-flow time

To investigate the association between low-flow time (LFT) and outcomes in out-of-hospital cardiac arrest (OHCA) patients treated with prehospital extracorporeal cardiopulmonary resuscitation (ECPR).

This retrospective study included OHCA patients receiving prehospital ECPR (July 2023-August 2024). LFT, defined as the interval from conventional CPR start to ECPR flow initiation, was analyzed continuously (per 10 min increment). Due to limited events (13 favorable neurological outcomes), the primary logistic regression adjusted for two prespecified confounders (age, initial shockable rhythm). A sensitivity analysis was performed in patients with witnessed arrest and bystander CPR (no-flow time of approximately 0). All analyses are exploratory.

Among 76 patients (mean age 58.80 ± 14.84 years, mean LFT 60.33 ± 13.89 min), survival to hospital discharge was 34.2% (26/76) and favorable neurological outcome 17.1% (13/76). Each 10 min LFT increase was associated with lower survival (aOR 0.557; 95% CI 0.368-0.844; P = 0.006) and favorable neurological outcome (aOR 0.461; 95% CI 0.255-0.834; P = 0.011). In the sensitivity subgroup (witnessed + bystander CPR, n = 44, 9 favorable outcomes), the univariable OR for favorable outcome was 0.395 (95% CI 0.176-0.886; P = 0.024), consistent with the primary estimate. Exploratory ROC analysis for favorable neurological outcome gave an AUC of 0.750 (95% CI 0.603-0.896), but the derived cutoff (55.5 min) is not proposed for clinical use.

In this single-center study, longer LFT (per 10 min) was associated with worse outcomes, consistent in a no-flow-time-controlled subgroup. Given the exploratory design, external validation is required. No definitive LFT threshold can be recommended.