The utility of bispectral index monitoring in general anesthesia

BACKGROUND: The Bispectral Index (BIS), a parameter derived from the electroencephalograph, has been shown to correlate with increasing sedation and loss of consciousness. This study was designed to investigate whether using BIS would improve anaesthetic drug management and immediate recovery after anaesthesia. METHODS: 160 patients undergoing abdominal surgery were studied. The patients were randomised to receive either propofol or sevoflurane anaesthesia. In each group 40 patients were anaesthetised with BIS monitoring and 40 without BIS. In BIS groups, propofol and sevoflurane dose was adjusted to achieve a target BIS values between 40-60 during the whole procedure. Drug consumption, intraoperative responses, times of recovery after anaesthesia and a "Clinical Quality Scale of Recovery" score were recorded from blinded observators. RESULTS: Demographic data were similar between groups. BIS monitoring improved the immediate recovery after propofol anaesthesia, while no significant differences were observed in patients receiving sevoflurane. The consumption of both propofol and sevoflurane significantly decreased (30 and 40%, respectively). There was no significant differences in the incidence of intraoperative responses between groups. The BIS groups had a higher percentage of patients with better ICU assessments. CONCLUSIONS: BIS monitoring decreased the consumption of both propofol and sevoflurane and facilitated the immediate recovery after propofol anaesthesia. Intraoperative course was not changed. These findings indicate that the use of BIS may be a valuable guide of the intraoperatively administration of propofol and sevoflurane.