BACKGROUND: BIS monitoring has been found to decrease the requirements for volatile anesthetics and to improve recovery. We wanted to assess the effect of BIS monitoring on intraoperative sevoflurane consumption, early recovery profile, and on postoperative nausea and vomiting.

METHODS: Forty ASA class 1 or 2 female patients undergoing mastectomy or thyroidectomy were studied. General anesthesia was induced with propofol (2.0 mg/kg) and fentanyl (1.5µg/kg), and maintained with 50% nitrous oxide-oxygen and sevoflurane inhalation. In the control group, sevoflurane was administered according to standard clinical practice. In the BIS group, sevoflurane was titrated to maintain a BIS value between 40 and 60 during surgery and of more than 65 during the last 15 minutes prior to the end of surgery. Sevoflurane consumption was measured. Time to response, time to self respiration, time to extubation, and time to orientation were recorded. Postoperative nausea and vomiting were evaluated by incidence and by using a visual analogue scale (VAS).

RESULTS: Sevoflurane consumption in the BIS group was 30.4% lower than in the control group (P < 0.05). All recovery times were significantly shorter in the BIS group than in the control group (P < 0.05), but, no differences in postoperative nausea and vomiting were observed between the groups.

CONCLUSIONS: BIS monitoring decreased and sevoflurane consumption and promoted early recovery. But BIS monitoring did not decrease postoperative nausea and vomiting.