Out-of-hospital cardiac arrest outcomes following EMS resuscitation protocol revision during the COVID-19 pandemic: a population-based study.

Aim: We aimed to evaluate the association between emergency medical service (EMS) protocols with enhanced infection control precautions against COVID-19 and the outcomes of patients with out-of-hospital cardiac arrest (OHCA), as well as various EMS-related time intervals, in Japan. Methods: We conducted a population-based cohort study of OHCAs in Kobe, Japan, between 2016 and 2023. In May 2020, the Japanese resuscitation protocols for EMS were revised in accordance with the guidance of the International Liaison Committee on Resuscitation. The outcomes of interest were favourable neurological outcomes and several time metrics related to EMS activities. We evaluated changes in outcomes before and after the protocol revision using segmented regression for interrupted time-series analyses. Results: A total of 10,126 patients were enrolled during the period. The proportion of favourable neurological outcomes decreased after the protocol revision: the change in the intercept was -3.4 % (95 % confidence interval [CI], -5.2 % to -1.7 %) and in the trend was 0.01 % (95 % CI, -0.02 % to 0.04 %). Delays were observed in airway management completion (186 s [95 % CI, 131 to 241] for the intercept and 6.13 s [95 % CI, 4.22 to 8.03] for the trend) and establishment of intravenous access (99 s [95 % CI, 55 to 143] for the intercept and 3.93 s [95 % CI, 2.84 to 5.02] for the trend). Conclusion: OHCA outcomes worsened after the protocol revision, with delays in several key EMS interventions. When encountering future pandemics, resuscitation protocols should be designed to balance infection control and the quality of advanced life support.