Epidural patient-controlled analgesia after cesarean section: buprenorphine-0.015% bupivacaine with epinephrine versus fentanyl-0.015% bupivacaine with and without epinephrine.

We compared the analgesia, side effects, and plasma concentrations of buprenorphine and fentanyl in a double-blind study of 78 parturients receiving one of these drugs by patient-controlled epidural infusion after elective cesarean section with epidural anesthesia. Patients were randomized to three epidural infusion groups: group 1 (n = 26), 3 micrograms/mL buprenorphine with 0.015% bupivacaine and 1 microgram/mL epinephrine; group 2 (n = 26), 3 micrograms/mL fentanyl with 0.015% bupivacaine and 1 microgram/mL epinephrine; and group 3 (n = 26), 3 micrograms/mL fentanyl with 0.015% bupivacaine. Plasma for determination of opioid concentrations was obtained in some subjects in each group at intervals up to 48 h during the infusion and in some subjects from each group at intervals after the infusion was stopped. Pain relief was similar and satisfactory in all three groups. The median overall satisfaction scores were high for all three groups. Pruritus was more common in the fentanyl groups (P less than 0.05). However, vomiting was more disturbing to the patients and seen only with buprenorphine. No patient had a respiratory rate less than 12 breaths/min. Epinephrine use was associated with a slower infusion rate (P less than 0.05, group 2 vs 3). All patients were able to ambulate without difficulty. Mean opioid plasma concentrations did not exceed 1.5 ng/mL. Thus, epidural patient-controlled analgesia in all three groups provided excellent analgesia, permitted ambulation, and was without serious side effects. Epidural buprenorphine offered no advantages over epidural fentanyl.