Comparison of 0.25 mg and 0.1 mg intrathecal morphine for analgesia after Cesarean section

To test the hypothesis that 0.1 mg intrathecal morphine plus NSAIDs provides satisfactory analgesia post-Cesarean section with fewer side effects than 0.25 mg intrathecal morphine.

Sixty women, scheduled for elective Cesarean section under spinal anesthesia, were randomized to receive either 0.1 mg or 0.25 mg intrathecal morphine combined with hyperbaric bupivacaine 0.75% and 20 microg fentanyl. All patients received a 100 mg indomethacin suppository at the end of surgery and 500 mg naproxen p.o. b.i.d. was started the evening of surgery and continued until discharge. A blinded researcher recorded the pain, pruritus, and nausea scores, the time to first request for additional analgesics, a visual analogue scale (VAS) satisfaction score, and the use of additional opioids, antipruritics, and/or antiemetics.

Of the 60 patients enrolled, two were not included in the data analysis because of protocol violations leaving 30 patients in the 0.1 mg group and 28 in the 0.25 mg group. There were no differences in the VAS pain scores or the number of women requesting an opioid other than codeine between the two groups. The VAS pruritus scores in the 0.1 mg group were lower throughout the 24 hr (P < 0.001). Fewer women in the 0.1 mg group (4/30 vs 12/28) requested nalbuphine to treat itching (P = 0.018). Nausea scores were lower in the 0.1 mg group (P < 0.001).

The use of 0.1 mg intrathecal morphine plus NSAIDs provides analgesia of similar quality to 0.25 mg but with fewer undesirable side effects following Cesarean section.