Small doses of intrathecal morphine combined with systemic diclofenac for postoperative pain control after cesarean delivery

Abstract

Postoperative pain control after cesarean delivery under spinal anesthesia is effectively obtained with morphine 0.1-0.3 mg intrathecally, although there may be dose-dependent side effects. We evaluated the quality of analgesia and the incidence of side effects with smaller doses of intrathecal morphine combined with intramuscular (i.m.) diclofenac. One hundred-twenty pregnant patients were allocated into six groups, which received the following treatments: Groups 1, 3, and 5 received 0.1, 0.05, and 0.025 mg of intrathecal morphine, respectively, plus 75 mg of i.m. diclofenac every 8 h; Groups 2, 4, and 6 received 0.1, 0.05, and 0.025 mg of intrathecal morphine, respectively, plus i.m. diclofenac on demand. Spinal anesthesia was performed with 15 mg of 0.5% hyperbaric bupivacaine. Pain scores and side effects were evaluated hourly for the first 24 h. Groups 1 and 2 had lower pain scores than Groups 3, 4, 5, and 6. However, only patients in Groups 2, 4, and 6 requested additional analgesics. Severe pruritus was more frequent in Groups 1 and 2. No patient experienced respiratory depression. We conclude that there is no advantage in using doses larger than 0.025 mg of intrathecal morphine if they are combined with systemic diclofenac.

Implications: A multimodal approach to pain control may provide good quality analgesia while reducing drug-related side effects. In this study, a very small dose of intrathecal morphine, in association with intramuscular diclofenac, proved effective for controlling pain after cesarean delivery, with a low incidence of morphine-induced pruritus.