The Effect of anesthesia depth monitoring on postoperative delirium in elderly patients: A systematic review and meta-analysis

To evaluate the effect of anesthesia guided by intraoperative electroencephalogram monitoring on postoperative delirium in elderly patients. Several databases were searched and randomized controlled trials were included. The incidence of postoperative delirium was used as the main index, and meta-analysis was performed. A total of 9 studies involving 5274 patients were included. 6 studies showed that there was no significant difference in the incidence of postoperative delirium between EEG-guided anesthesia and no monitoring (OR = 0.84, 95 % CI: 0.628-1.122, P = 0.24, I 2 = 70 %), and the publication bias was not obvious (Begg test, P = 0.33). 3 studies found that deep anesthesia significantly increased the risk of postoperative delirium compared with shallow anesthesia (OR = 1.77, 95 % CI: 1.201-2.617, P < 0.01, I 2 = 2 %). The overall risk of bias was low, but there were partial measurement and sampling bias. Sensitivity analysis suggested that Matthew T.V. Chan and Troy S Wildes study may be the source of heterogeneity. After excluding the Troy S Wildes study, the OR was 0.76 (95 % CI: 0.637-0.906). Subgroup analysis showed that EEG monitoring could significantly reduce the incidence of postoperative delirium in Chinese studies (OR = 0.58, 95 % CI: 0.422-0.801, I 2 = 0 %), while there was no significant difference between European and American studies (OR = 0.96, 95 % CI: 0.722-1.265, I 2 = 65 %). EEG-guided anesthesia has no significant effect on postoperative delirium, but deep anesthesia significantly increases its risk.