Efficacy of intrathecal morphine for analgesia following elective cesarean section: comparison with previous delivery

Abstract

Purpose: To determine the effect of intrathecal injection of morphine 0.2 mg on postoperative analgesia, activity and satisfaction after elective cesarean section.

Method: Forty-five parturients who had previously undergone cesarean section with spinal anesthesia without intrathecal morphine were enrolled in this randomized, double-blinded study. Group 1 received hyperbaric bupivacaine 10 mg intrathecally (IT) and group 2 received morphine 0.2 mg IT in addition to hyperbaric bupivacaine 10 mg IT. All subjects received 20 mg piroxicam rectally at the end of surgery and 18 hours after surgery. Side effects in the first 24 hours after delivery were recorded by a trained nurse. Pain, nausea, pruritus, and satisfaction during the first 24 hours were self-rated using a visual analog scale. Subjects also recorded their memories of these symptoms after their previous cesarean sections. The time to first request for additional analgesics (30 mg pentazocine intramuscularly), total dose of pentazocine within 24 hours postoperatively and nurse observations of walking status within 24 hours postoperatively were also recorded.

Results: In the present cesarean sections, the duration of complete analgesia and the time to first request for additional analgesics were longer in group 2 than in group 1. Group 2 had higher satisfaction scores than group 1 in spite of their more severe pruritus and nausea during the first 24 hours after surgery. The percentage of patients who could not walk during the first 24 hours after cesarean section was higher in group 1 than in group 2.

Conclusion: The addition of morphine 0.2 mg to hyperbaric bupivacaine 0.5% by intrathecal injection reduced postoperative pain and analgesic use, and increased patient satisfaction following cesarean section. The combination of intrathecal injection of morphine and preventive NSAIDs can be easily administered in most hospitals, and is substantially less expensive than the new pain management technologies currently in use.