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

In several studies, regional cerebral oxygen saturation (rSO 2 ) has been measured in patients with postcardiac arrest syndrome (PCAS) to analyze the brain's metabolic status. However, the significance of rSO 2 in PCAS patients remains unclear. In the present study, we investigated the relationship between rSO 2 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 rSO 2 and additional parameters (arterial oxygen saturation [SaO 2 ], hemoglobin [Hb], mean arterial pressure [MAP], arterial carbon dioxide pressure [PaCO 2 ], 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 rSO 2 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 rSO 2 value between the two groups at any time point. The multiple regression analysis of the favorable group revealed a moderate correlation between rSO 2 and SaO 2 , Hb, and PaCO 2 only at 24 hours (coefficients: 0.482, 0.422, and 0.531, respectively), whereas that of the unfavorable group revealed moderate correlations between rSO 2 and Hb values at all time points, PaCO 2 at 24 hours and MAP at 24 and 48 hours. rSO 2 was moderately correlated to MAP in unfavorable patients. To optimize brain oxygen metabolic balance for PCAS patients with TTM measuring rSO 2 , we suggest total evaluation of each parameters of SaO 2 , Hb, MAP, and PaCO 2 .