Intra-arrest Transport and Neurological Outcomes in Out-of-Hospital Cardiac Arrest with Initial Shockable Rhythm Who Failed the First Defibrillation: A Nationwide Study in Limited Prehospital ACLS Settings.

Abstract

Objectives: Early hospital transport may benefit out-of-hospital cardiac arrest (OHCA) patients with shockable rhythms who are refractory to defibrillation, particularly in settings with limited advanced on-scene interventions. However, its impact in emergency medical service (EMS) systems with limited advanced cardiac life support (ACLS) capabilities remain unclear. This study aimed to assess the association between intra-arrest transport and survival outcomes in OHCA patients with initial shockable rhythms who remained in refractory shockable rhythms despite the first defibrillation attempt.

Methods: Using a nationwide OHCA registry from a country with an intermediate prehospital service level where interventions such as prehospital anti-arrhythmic drugs or double sequential defibrillation are not feasible, adult medical OHCA patients with initial shockable rhythms who failed the first defibrillation between January 1, 2015, and December 31, 2022 were analyzed. The primary outcome was good neurological recovery. Time-dependent propensity score matching was performed to assess the association between intra-arrest transport and survival outcomes. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated, and stratified analyses were performed based on matched time intervals after the first defibrillation.

Results: Of 10,246 eligible patients, 8,131 underwent intra-arrest transport. After 1:1 time-dependent propensity score matching, 2,332 patients each in the intra-arrest transport and on-scene resuscitation groups were included. In the matched cohort, intra-arrest transport was not associated with good neurological recovery (11.7% and 11.5% in the intra-arrest transport and on-scene resuscitation groups, respectively; RR (95% CI) 0.97 (0.91-1.07)). In the stratified analyses based on matched time intervals after the first defibrillation, intra-arrest transport within 5 minutes after the first defibrillation was associated with poorer neurological outcomes (RR (95% CI) 0.86 (0.77-0.97)).

Conclusions: In an EMS setting with a limited-service level, intra-arrest transport showed no benefit for OHCA patients with an initial shockable rhythm who remained in refractory shockable rhythms despite the first defibrillation attempt. High-quality on-scene management is crucial before the initiation of hospital transport. Further research is needed to develop integrated systems ensuring effective prehospital and hospital care.