The association between regional cerebral oxygen saturation and neurological outcomes in cardiac arrest survivors

Regional cerebral oxygen saturation (rSO2) is recommended for monitoring cerebral perfusion status. We aimed to investigate the association between rSO2 and neurological outcomes and correlating parameters with rSO2 in cardiac arrest survivors. This observational study included adult comatose cardiac arrest survivors who underwent targeted temperature management and were monitored with rSO2 between June 2021 and February 2023. We collected rSO2 values monitored after admission to the intensive care unit at initial, last, 24 hours, 48 hours, and 72 hours after return of spontaneous circulation. We calculated the minimum, maximum, and average rSO2 values. The primary outcome was the 6-month neurological outcome assessed using the Cerebral Performance Category (CPC) scale, dichotomized into good (CPC 1 or 2) or poor (CPC 3-5). Among the 78 included patients, 33.3% (26 patients) had poor neurological outcomes. The poor neurological outcome group exhibited lower maximum rSO2 (78.5 [70.0-86.8] vs 89.0 [78.3-95.00], P = .006) and lower last rSO2 (58.0 [45.3-71.8] vs 70.0 [56.2-85.3], P = .010). Initial, minimum, and average rSO2 did not differ between neurological outcome groups. The rSO2 significantly changed over 24 hours, 48 hours, and 72 hours after return of spontaneous circulation (P = .001). Maximum rSO2 (odds ratio [OR] 0.931; 95% confidence intervals [CIs] 0.885-0.980), last rSO2 during 72 hours (OR 0.950; 95% CIs 0.918-0.983) and rSO2 at 48 hours (OR 0.959; 95% CIs 0.920-0.998) were independently associated with poor neurological outcomes. Among hemoglobin, PCO2, PO2, and mean arterial pressure (MAP), hemoglobin correlated with rSO2 in both neurological outcomes, while MAP only showed an association with rSO2 in the poor neurological outcomes group (R = 0.292). Lower maximum, 48 hours, and last rSO2 values were associated with poor neurological outcomes. The rSO2 was dependent on MAP in patients with poor neurological outcomes.