Postoperative recovery with bispectral index versus anesthetic concentration-guided protocols

Background: Use of the bispectral index (BIS) monitor has been suggested to decrease excessive anesthetic drug administration, leading to improved recovery from general anesthesia. The purpose of this substudy of the B-Unawareand BAG-RECALL trials was to assess whether a BIS-based anesthetic protocol was superior to an end-tidal anesthetic concentration-based protocol in decreasing recovery time and postoperative complications. Methods: Patients at high risk for awareness were randomized to either BIS-guided or end-tidal anesthetic concentration-guided general anesthesia in the original trials. Outcomes included time to postanesthesia care unit discharge readiness, time to achieve a postoperative Aldrete score of 9-10, intensive care unit length of stay, postoperative nausea and vomiting, and severe postoperative pain. Univariate Cox regression and chi-square tests were used for statistical analyses. Results: The BIS cohort was not superior in time to postanesthesia care unit discharge readiness (hazard ratio, 1.0; 95% CI, 1.0-1.1; n = 2,949), time to achieve an Aldrete score of 9-10 (hazard ratio, 1.2; 95% CI, 1.0-1.4; n = 706), intensive care unit length of stay (hazard ratio, 1.0; 95% CI, 0.9-1.1; n = 2,074), incidence of postoperative nausea and vomiting (absolute risk reduction,-0.5%; 95% CI,-5.8 to 4.8%; n = 789), or incidence of severe postoperative pain (absolute risk reduction, 4.4%; 95% CI,-2.3 to 11.1%; n = 759). Conclusions: In patients at high risk for awareness, the BIS-guided protocol is not superior to an anesthetic concentration-guided protocol in time needed for postoperative recovery or in the incidences of common postoperative complications.