Does using the bispectral index (BIS) during craniotomy affect the quality of recovery?

One of the aims of neuroanesthesia is to provide early postoperative recovery and neurologic examination in patients undergoing supratentorial surgery. Our aim was to investigate the role of using the bispectral index (BIS) in recovery from anesthesia and altering drug administration in patients undergoing craniotomy. Fifty American Society of Anesthesiologists' (ASA) physical status I-II patients undergoing craniotomy were included in the study. The patients were randomly divided into two groups, and all patients received standard induction drugs, and 0.8%-1.5% sevoflurane was used for maintenance of anesthesia. In the BIS-guided group, the concentration of sevoflurane was titrated to maintain BIS at 40-60. In the control group, the anesthesiologist was blind to BIS, and the concentration of sevoflurane was changed according to the patients' hemodynamic changes. The hemodynamic data, BIS values, and sevoflurane concentrations were recorded every 15 minutes. In addition, the BIS value was recorded by the primary anesthetist in the BIS-guided group and by another independent anesthetist in the control group. At the end of the study, recovery criteria and Aldrete recovery scores were recorded every 15 minutes. Neurologic assessments were performed when the Aldrete score was 9-10. BIS values were higher, and sevoflurane concentrations (P < 0.05) and total doses of fentanyl (P < 0.01) were lower, in the BIS-guided group. Times to first spontaneous breathing, eye opening, and extubation (P = 0.035, P = 0.001, and P = 0.0001, respectively) were significantly shorter in the BIS-guided group. Time to an Aldrete score of 9-10 and adequate neurologic assessment were similar between the groups. In conclusion, BIS monitoring by supratentorial craniotomy under general anesthesia reduced the maintenance anesthetic concentration and narcotic drug usage and lowered the recovery times from general anesthesia.