Bispectral Index–Based General Anesthesia May Reduce the Amount of Propofol

Mika Hiki, Fumiko Horiuchi, *Kenji Atarashi, Osamu Nagata, and Makoto Ozaki

Department of Anesthesiology, Tokyo Women’s Medical University, Tokyo, Japan,

* Itabashi Cyuou General Hospital

We examined the average rate of propofol infusion, extubation time, and PACU staying time to evaluate the advantage of Bispectral Index (BIS) monitoring during general anesthesia with propofol.

Methods:

Two groups of subjects were prepared by randomly assigning 23 patients (9 male and 14 female, aged 20 to 70years old, ASA physical status 1or 2) without neurological dysfunction or hypertension who were scheduled to undergo general surgical procedures lasting for more than 2 hours. After the premedication with clonidine, general anesthesia was induced with propofol and vecuronium, and maintained with propofol, fentanyl, and nitrous oxide. In the BIS group, propofol infusion rate was regulated to keep the BIS value from 40 to 60. In the SP group, propofol infusion rate was regulated to keep the vital signs stable. After the operation, the patients were extubated, moved to the PACU, and observed until the Observer’s Assessment of Alertness Sedation Score reached a level of 4 or 5.

Results:

There were no significant differences between the two groups in the backgrounds of patients or the amounts of fentanyl infused. The average rate of propofol infusion in the BIS group(5.7±0.5 mg/kg/h )was smaller than that (6.0±1.1 mg/kg/h)in the SP group. Time up to the patient’s departure from the PACU were similar in the BIS (27.5±7.8min)and the SP (27.5±11.7min) groups.

Conclusions

BIS-based general anesthesia may reduce the amount of propofol necessary to maintain the hypnotic level of BIS from 40to 60.