Intravenous Droperidol Causes a Reduction in the Bispectral Index in Propofol-Sedated Patients During Spinal Anesthesia

We investigated the effect of IV droperidol on the bispectral index (BIS) in conscious and propofol-sedated patients during spinal anesthesia. Thirty minutes after the induction of spinal anesthesia, 20 patients were given 2 mg of droperidol IV without administration of other sedatives (conscious group). Another group of patients were sedated with a propofol infusion to maintain BIS at 60 ± 5 and were administered IV saline (placebo group;n = 20), droperidol 1 mg (dro-1 group;n = 20), or droperidol 2 mg (dro-2 group;n = 20) in a randomized order and in a double-blinded fashion. Although BIS remained the same in the conscious and placebo groups, it significantly decreased after administration of droperidol in the dro-1 and dro-2 groups. The decrease in BIS was significantly larger in the dro-2 group than in the dro-1 group. These results suggest that an antiemetic dose of droperidol enhances the hypnotic effect of propofol in a dose-dependent manner during spinal anesthesia.