The Effect of Changes in Cerebral Oximeter Values During Cardiac Surgery on the Incidence of Postoperative Cognitive Dysfunction (POCD): a Retrospective Study Based on Propensity Score Matched Analysis

Background The occurrence of postoperative cognitive dysfunction(POCD) after major cardiac surgery is associated with an increase in perioperative mortality and morbidity. The increased regional cerebral oxygen saturation(rSO2) value is likely related to increased POCD due to oxidative stress. The incidence of POCD in relation to an increase in rSO2 values is not clinically known yet. Methods Among 3482 patients underwent cardiac surgery, 976 patients were allocated for this retrospective study. Of these, 230 patients (32.5%) were observed to have postoperative neurologic symptoms. After propensity score 1:2 ratio matching, a total of 690 patients were included in the analysis. Recorded data on occurrence of POCD from the postoperative period to predischarge were collected from the electronic records. Results The mean baseline rSO 2 value was higher in the POCD (–) group than in the POCD (+) group (61.9 ± 9.6 vs 55.3 ± 11.4; P < 0.001). The mean overall minimum rSO 2 value was lower in the POCD (+) group (52.2 ± 8.3 vs 48.3 ±10.5, P < 0.001). As compared with baseline, the POCD (+) group had significantly higher values in the CPB preweaning and CPB post-weaning periods ( P < 0.001, respectively). There was a greater decrease in the overall minimum rSO 2 values compared with baseline in the POCD (–) group ( P < 0.001). The maximum mean rSO 2 changes compared with baseline were higher in the POCD (+) group (adjusted odds ratio, 1.08; 95% confidence interval [CI], 1.04–1.11; P < 0.001). The AUROC for delta values of minimal compared with baseline values was 0.62 and the AUROC for the delta values of maximal compared with baseline values was 0.72. Conclusions Increased cerebral oximeter levels relative to baseline values has an effect on the development of POCD. Intraoperative oxidative damage was associated with increased POCD, and increased cerebral oximeter levels during cardiac surgery can also be a risk factor for POCD.