Randomized double-blind controlled clinical trial for the evaluation of post-partum analgesia using epidural morphine: analgesic effectiveness of different dose regimes compared with placebo

Abstract

Introduction: Prior studies have shown that the conventional management of post-partum pain (acetaminophen, NSAIDS) is insufficient. In our setting, no advantage is taken of the epidural catheter placed as part of the analgesic management of pregnant women during labor.

Objective: To determine the efficacy of 2 and 3 mg doses of epidural morphine used for analgesia during vaginal post-partum in patients receiving epidural analgesia for labor, compared to placebo.

Patients and methods: Double-blind randomized clinical trial with 114 patients, in which 38 patients received 10 ml of anesthetic solution with 2 mg of epidural morphine, 39 received 3 mg of epidural morphine, and another 37 received 10 ml of 0.9% epidural saline solution (control group), 1 hour after labor. The analgesic efficacy and the side effects occurring within the first 24 hours after administration were evaluated.

Results: The dose of morphine was effective at controlling pain after delivery, making it possible to reduce the need for additional analgesia in the group receiving 2 mg (NNT=4.56), as well as in the group receiving 3 mg of morphine (NNT=3.66). The outcome was more marked in patients who needed perineorrhaphy (NNT =1.6) and in primiparity cases (NNT 2.4). In the experimental group, the analgesic effect extended over the 24-hour follow-up period. The incidence of side-effects in each of the treatment groups was as follows: pruritus, 30% and 36%; nausea, 18.4% and 15.4%; vomiting, 7.9% and 15.4%.

Conclusions: The use of epidural morphine during the immediate post-partum period is effective for managing pain ensuing after labor. Although there was evidence of adverse side effects at the doses used, they were tolerable and did not require treatment. The present management of post-partum analgesia is insufficient.