Cerebral monitoring of anaesthesia on reducing cognitive dysfunction and postoperative delirium: a systematic review

Objective: To assess the efficacy of cerebrally monitoring the depth of anaesthesia in reducing postoperative cognitive dysfunction and postoperative delirium (POD). Methods: MEDLINE, EMBASE, and Cochrane Library databases were searched following PRISMA statement guidelines. We included randomized clinical trials (RCTs) comparing electroencephalogram-based and routine care-guided titration of anaesthesia in a systematic review. The risk estimate from each RCT was pooled in a meta-analysis. The primary outcome was POD and long-term cognitive dysfunction. Subgroup analyses were conducted for the sub-types of intervention group and surgery. We identified five RCTs with a total sample size of 2,868 and with bispectral index (BIS) or auditory evoked potential (AEP) as interventions. Results: The odds ratio (OR) for POD and long-term cognitive decline was 0.51 (95% CI: 0.35-0.76) and 0.69 (95% CI: 0.49-0.97), respectively. Significant heterogeneity was identified in the POD data. There was no significant difference between BIS- and AEP-based titration of anaesthesia in reducing the risk of POD. Extensive heterogeneity for cardiac and thoracic surgery was identified in the study population, and significant publication bias was found among the POD results. Conclusions: BIS- and AEP-guided anaesthesia are associated with significantly reduced risk of POD and long-term cognitive dysfunction.