[Intrathecal fentanyl reduces the dose of propofol required for sedation during spinal anesthesia]

To assess the effects of 2 dosages of intrathecal fentanyl on the requirement for propofol infused intravenously for the sedation of patients under spinal anesthesia.

We conducted a prospective controlled clinical trial enrolling patients in ASA physical status class 1 randomly assigned to 3 groups. Group 1 received 12.5 mg of 0.75% hyperbaric bupivacaine; group 2, 12.5 mg of bupivacaine plus 15 microg of fentanyl; group 3, 12.5 mg of bupivacaine plus 25 microg of fentanyl. After initiation of spinal anesthesia, monitoring of the bispectral (BIS) index (BIS XP A-2000) was begun, and sedation was maintained with a propofol infusion through a target-controlled infusion device (Orchestra Base Primea) for an initial effect-site concentration of 2.5 microg mL(-1), which was adjusted to maintain the BIS index between 60 and 75. We recorded BIS indices, noninvasive blood pressure, electrocardiogram, oxygen saturation, nasal end-tidal carbon dioxide pressure, mean infusion dose of propofol, total infusion dose of propofol, time until awakening, propofol consumption, and adverse effects.

Seventy-five patients (25 in each group) were enrolled. Patient characteristics and BIS indices were similar in all groups. Propofol doses were significantly lower and times until awakening were significantly shorter in groups 2 and 3 than in group 1 (P < .01). The incidences of pruritus were significantly higher in groups 2 and 3.

Adding 15 or 25 microg of fentanyl to hyperbaric bupivacaine lowers the dose of intravenous propofol required for sedation of patients under spinal anesthesia.