What is the impact of perioperative cerebral oxygen desaturation on postoperative delirium in old population: a systemic review and meta-analysis

Background Perioperative cerebral oxygen saturation (ScO 2 ) has been reported to associate with postoperative delirium (POD) which is a common postoperative complication, however, the results were inconclusive. Therefore, we aimed to conduct an up-to-date review and meta-analyze the relationship between perioperative ScO 2 and POD. Methods We systematically searched PubMed, Embase and Web of science through January 13, 2022. The pooled results were estimated through a random-effects model meta-analysis and expressed as odds ratios (ORs) and standard mean differences (SMDs), accompanied with 95% confident intervals (CIs). Results Finally, of 467 searched articles, ten articles were included. A total of six studies reported the baseline ScO 2 value and the pooled result showed that preoperative baseline ScO 2 was lower in POD groups (SMD = − 0.41, 95% CI − 0.64 to − 0.18). And beyond that, the pooled OR across four literatures about preoperative low ScO 2 on POD was 3.44 (95% CI 1.69, 7.02). In contrast, insignificant differences were detected in baseline/lowest ScO 2 value during intraoperative and postoperative period. Additionally, there were no statistically significant associations for intraoperative and postoperative low ScO 2 effect on POD risk. Meta-regress analysis has found no significant impact factors. Conclusions Based on current evidence, POD patients have a lower ScO 2 , and ScO 2 desaturation may increase POD incidence, indicating the role of ScO 2 underlying pathological mechanisms. For generalizability of evidence, we should rely on high-quality, considering more comprehensively longitudinal, interdisciplinary studies.