Postcesarean analgesia with spinal morphine, clonidine, or their combination

Abstract

In this randomized, double-blind trial in 240 women, we investigated the analgesic efficacy and duration of subarachnoid fentanyl 15 microg with morphine, clonidine, or both morphine and clonidine for cesarean delivery. A dose-finding analysis showed similar postoperative efficacy and side effects for groups receiving morphine 100 microg with clonidine 60, 90, or 150 microg. Data from these groups were combined (MC60-150, n = 113) and compared with groups receiving morphine 100 microg (n = 39), clonidine 150 microg (n = 39), or morphine 100 microg plus clonidine 30 microg (n = 41). The four groups differed in the time to patient-controlled morphine use and cumulative morphine consumption (P < 0.0001 and P < 0.001, respectively), with the longest duration and smallest dose in MC60-150. Pain scores were significantly different among groups. Onset of sensory block, ephedrine requirement and incidence of hypotension, patient satisfaction, and recovery were similar. Groups receiving clonidine had greater sedation, those receiving morphine had more severe pruritus, and group MC60-150 showed a trend to more vomiting intraoperatively. Compared with morphine 100 microg or clonidine 150 microg alone, the combination of subarachnoid morphine 100 microg and at least 60 microg of clonidine was found to increase the duration of postcesarean analgesia, reduce opioid requirement, and increase intraoperative sedation.

Implications: A multimodal approach to postcesarean analgesia, using subarachnoid bupivacaine, fentanyl, morphine 100 microg, and clonidine 60 microg, improves pain relief compared with morphine 100 microg or clonidine 150 microg alone, but increases intraoperative sedation and may increase perioperative vomiting.