Association between defibrillation-to-adrenaline interval and short-term outcomes in patients with out-of-hospital cardiac arrest and an initial shockable rhythm

Aim: The optimal timing of adrenaline administration after defibrillation in patients with out -of -hospital cardiac arrest (OHCA) and an initial shockable rhythm is unknown. We investigated the association between the defibrillation -to -adrenaline interval and clinical outcomes. Methods: Between 2011 and 2020, we enrolled 1,259,960 patients with OHCA into a nationwide prospective population -based registry in Japan. After applying exclusion criteria, 20,905 patients with an initial shockable rhythm documented at emergency medical services (EMS) arrival who received adrenaline after defibrillation were eligible for this study. Multivariable logistic regression analysis was used to predict favourable shortterm outcomes: prehospital return of spontaneous circulation (ROSC), 30 -day survival, or a favourable neurological outcome (Cerebral Performance Category 1 or 2) at 30 days. Patients were categorised into 2 -minute defibrillation -to -adrenaline intervals up to 18 min, or more than 18 min. Results: At 30 days, 1,618 patients (8%) had a favourable neurological outcome. The defibrillation -to -adrenaline interval in these patients was significantly shorter than in patients with an unfavourable neurological outcome [8 (5-12) vs 11 (7-16) minutes; P < 0.001]. The proportion of patients with prehospital ROSC, 30 -day survival, or a favourable neurological outcome at 30 days decreased as the defibrillation -to -adrenaline interval increased (P < 0.001 for trend). Multivariable analysis revealed that a defibrillation -to -adrenaline interval of > 6 min was an independent predictor of worse prehospital ROSC, 30 -day survival, or neurological outcome at 30 days when compared with an interval of 4-6 min. Conclusion: A longer defibrillation -to -adrenaline interval was significantly associated with worse short-term outcomes in patients with OHCA and an initial shockable rhythm.