Parameters Influencing Brain Oxygen Measurement by Regional Oxygen Saturation in Postcardiac Arrest Patients with Targeted Temperature Management

In several studies, regional cerebral oxygen saturation (rSO2) has been measured in patients with postcardiac arrest syndrome (PCAS) to analyze the brain's metabolic status. However, the significance of rSO2 in PCAS patients remains unclear. In the present study, we investigated the relationship between rSO2 and physiological parameters. Comatose survivors of out-of-hospital PCAS with targeted temperature management (TTM) at 34°C for 24 hours were included. All patients were monitored for their rSO2 and additional parameters (arterial oxygen saturation [SaO2], hemoglobin [Hb], mean arterial pressure [MAP], arterial carbon dioxide pressure [PaCO2], and body temperature]) measured at the start of monitoring and 24 and 48 hours after return of spontaneous circulation (ROSC). Patients were divided into favorable and unfavorable groups, and the correlation between rSO2 and these physiological parameters was evaluated by multiple regression analysis. Forty-nine patients were included in the study, with 15 in the favorable group and 34 in the unfavorable group. There was no significant difference in the rSO2 value between the two groups at any time point. The multiple regression analysis of the favorable group revealed a moderate correlation between rSO2 and SaO2, Hb, and PaCO2 only at 24 hours (coefficients: 0.482, 0.422, and 0.531, respectively), whereas that of the unfavorable group revealed moderate correlations between rSO2 and Hb values at all time points, PaCO2 at 24 hours and MAP at 24 and 48 hours. rSO2 was moderately correlated to MAP in unfavorable patients. To optimize brain oxygen metabolic balance for PCAS patients with TTM measuring rSO2, we suggest total evaluation of each parameters of SaO2, Hb, MAP, and PaCO2.