Hyperoxemia is Associated With Poor Neurological Outcomes in Patients With Out-of-Hospital Cardiac Arrest Rescued by Extracorporeal Cardiopulmonary Resuscitation: Insight From the Nationwide Multicenter Observational JAAM-OHCA (Japan Association for Acute Medicine) Registry

Background: Previous studies have shown an association between hyperoxemia and mortality in patients with out-of-hospital cardiac arrest (OHCA) after cardiopulmonary resuscitation (CPR); however, evidence is lacking in the extracorporeal CPR (ECPR) setting. Objective: The aim of this study was to test the hypothesis that hyperoxemia is associated with poor neurological outcomes in patients treated by ECPR. Methods: The Japanese Association for Acute Medicine OHCA Registry is a multicenter, prospective, observational registry of patients from 2014 to 2017. Adult (18 years or older) patients who had undergone ECPR after OHCA were included. Eligible patients were divided into two groups based on the partial pressure of oxygen in arterial blood (PaO₂) levels at 24 h after ECPR: the high-PaO₂ group (n = 242) defined as PaO₂ ≥ 157 mm Hg (median) and the low-PaO₂ group (n = 211) defined as PaO₂ 60 to < 157 mm Hg. The primary outcome was the favorable neurological outcome, defined as a Cerebral Performance Categories Scale score of 1 to 2 at 30 days after OHCA. Results: Of 34,754 patients with OHCA, 453 patients were included. The neurological outcome was significantly lower in the high-PaO₂ group than in the low-PaO₂ group (15.9 vs. 33.5%; p < 0.001). After adjusting for potential confounders, high PaO₂ was negatively associated with favorable neurological outcomes (adjusted odds ratio [aOR] 0.48; 95% confidence interval [CI] 0.24–0.97; p = 0.040). In a multivariate analysis with multiple imputation, high PaO₂ was also negatively associated with favorable neurological outcomes (aOR 0.63; 95% CI 0.49–0.81; p < 0.001). Conclusions: Hyperoxemia was associated with worse neurological outcomes in OHCA patients with ECPR.