Association Between Intraoperative Electroencephalogram Burst Suppression and Postoperative Delirium in Non-cardiac Surgery: A Systematic Review.

Postoperative delirium is a common complication in older surgical patients. Intraoperative EEG burst suppression may predict its occurrence. This study aimed to evaluate the association between burst suppression and postoperative delirium exclusively in non-cardiac surgery through systematic review and meta-analysis. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided systematic review was conducted using PubMed, Cochrane Library, and ScienceDirect. Eligible studies included adult non-cardiac surgical patients assessing EEG burst suppression and postoperative delirium. Risk of bias was evaluated using RoB 2, the Newcastle-Ottawa Scale, and the Joanna Briggs Institute tools. Meta-analysis employed a random-effects Mantel-Haenszel model, with narrative synthesis for studies lacking extractable data. Across the included studies, the incidence of postoperative delirium (POD) ranged from 8.9% to 26%. Meta-analysis demonstrated that intraoperative burst suppression was significantly associated with POD occurrence (OR: 1.73, 95% CI: 1.03-2.90; I² = 38%). Patients with POD had significantly longer burst-suppression duration (mean difference of 25.31 min; p < 0.00001; I² = 0%). The pooled adjusted analysis confirmed an independent association between burst suppression and POD (OR: 2.69, 95% CI: 1.90-3.81; I² = 31%). Individual studies supported a dose-dependent relationship between the duration of suppression and the risk of delirium. Anesthetic agents influenced the suppression burden - propofol was associated with longer durations, whereas desflurane was associated with increased POD risk, independent of suppression. Preoperative cognitive impairment and frailty were identified as significant effect modifiers, increasing susceptibility to burst suppression and subsequent delirium. Intraoperative EEG burst suppression is significantly associated with postoperative delirium in non-cardiac surgery. Duration and patient vulnerability influence risk, highlighting the potential of duration as a modifiable intraoperative predictor.