Continuous infusion epidural anesthesia during labor: a randomized, double-blind comparison of 0.0625% bupivacaine/0.002% butorphanol and 0.125% bupivacaine.

The efficacy of pain relief and the maternal and neonatal effects of continuous epidural infusion of 0.0625% bupivacaine/0.002% butorphanol was compared with the infusion of 0.125% bupivacaine alone in a randomized, double-blind study of 32 women in labor. A test dose of 2 ml 0.5% bupivacaine was given to every patient and followed by two epidural regimens in randomized, double-blind manner. Group B-B (bupivacaine/butorphanol) patients received 7.5 ml 0.125% bupivacaine plus 1 mg butorphanol (0.5 ml) followed by an infusion of 0.0625% bupivacaine/0.002% butorphanol at a rate of 12 ml/hour; Group B (bupivacaine alone) patients received 8 ml 0.25% bupivacaine followed by an infusion of 0.125% bupivacaine at a rate of 12 ml/hour. A bolus of 5 ml 0.125% bupivacaine or 0.0625% bupivacaine was given to Group B or B-B, respectively, if additional pain relief was required. Infusion of B-B combination resulted in similar pain relief and fewer patients with motor block than bupivacaine alone; 12% versus 38% in Groups B-B and B, respectively, had motor weakness. A smaller dose of bupivacaine was used in the B-B group compared to the B group; 71 +/- 14 versus 99 +/- 13 mg (mean +/- SEM; p less than 0.05). Progress of labor and the mode of delivery did not differ significantly between the two groups. All infants were vigorous and had normal acid-base status and neurologic adaptive capacity scores. Butorphanol appears to be useful as an adjunct to epidural bupivacaine for continuous epidural infusion during labor without adversely affecting the mother or the neonate.