Different benefit of bispectal index (BIS) in desflurane and propofol anesthesia

Bispectal index (BIS) monitoring may reduce drug usage and hasten recovery in propofol and inhalation anesthesia. The faster emergence profile of desflurane may reduce the effect of BIS monitoring on recovery from desflurane compared with propofol. This study compared hypnotic drug usage, recovery, patient satisfaction and incidence of inadequate sedation in BIS monitored and nonmonitored women anesthetized with desflurane or propofol.

One hundred and sixty patients scheduled for elective gynecological surgery were randomly assigned to desflurane or propofol anesthesia with and without BIS monitoring. Fentanyl, vecuronium and remifentanil were administered according to clinical criteria. The BIS monitor was used in all patients, but the monitor screen was covered in the controls. A BIS level between 45 and 55 was targeted in the BIS monitored patients whereas depth of anesthesia was assessed by clinical criteria in the controls.

The mean (SD) desflurane MAC-hours administered with and without BIS were 0.70 (0.15) and 0.76 (0.12), respectively, resulting in extubation times of 6.5 (4.1) and 8.3 (6.1) min. (NS). Bispectal index monitoring was associated with improved patient satisfaction, reduced postoperative nausea and antiemetic drug requirement, and fewer episodes with sustained BIS levels > 60. The mean (SD) propofol infusion rates were 6.0 (1.4) and 6.6 (0.9) mg kg(-1)h(-1) with and without the BIS monitor (P = 0.023), resulting in mean (SD) extubation times of 6.8 (4.6) and 10.5 min (5.9), respectively (P < 0.05).

Bispectal index monitoring reduced propofol usage and hastened recovery after propofol anesthesia, whereas in desflurane anesthesia it was associated with improved patient satisfaction, probably because of decreased postoperative nausea and fewer episodes of inadequate hypnosis.