Characteristics of regional cerebral oxygen saturation levels in patients with out-of-hospital cardiac arrest with or without return of spontaneous circulation: A prospective observational multicentre study

Aim: Our study aimed at filling the fundamental knowledge gap on the characteristics of regional brain oxygen saturation (rSO₂) levels in out-of-hospital cardiac arrest (OHCA) patients with or without return of spontaneous circulation (ROSC) upon arrival at the hospital for estimating the quality of cardiopulmonary resuscitation and neurological prognostication in these patients. Methods: We enrolled 1921 OHCA patients from the Japan - Prediction of Neurological Outcomes in Patients Post-cardiac Arrest Registry and measured their rSO₂ immediately upon arrival at the hospital by near-infrared spectroscopy using two independent forehead probes (right and left). We also assessed the percentage of patients with a good neurological outcome (defined as cerebral performance categories 1 or 2) 90 days post cardiac arrest. Results: After 90 days, 79 (4%) patients had good neurological outcomes and a median lower rSO₂ level of 15% (15-20%). Compared to patients without ROSC upon arrival at the hospital, those with ROSC had significantly higher rSO₂ levels (56% [39-65%] vs. 15% [15-17%], respectively; P<0.01), and significantly correlated right- and left-sided regional brain oxygen saturation levels (R=0.94 vs. 0.66, respectively). In both groups, the percentage of patients with a good 90-day neurological outcome increased significantly in proportion to their rSO₂ levels upon arrival at the hospital (P<0.01). Conclusion: Our data indicate that measuring rSO₂ levels might be effective for both monitoring the quality of resuscitation and neurological prognostication in patients with OHCA.