Can 0.15 mg. Intrathecal Morphine be as Effective as 0.2 mg in Post Cesarean Pain Control?

Abstract

Background: 0.2 mg. intrathecal morphine for post cesarean section provides good analgesia. However, side effects increase with higher dosage.
Objective: To compare the effectiveness and side effects of 0.15 mg. and 0.2 mg. intrathecal morphine.
Method: A prospective randomized study of term parturients undergoing cesarean section was done. Patients were randomized into 2 groups: group I (study group) and group II (control group) received 0.15 or 0.2 mg intrathecal morphine with 10 mg heavy bupivacaine for spinal anesthesia respectively. Tramadol was used as a rescue drug postoperatively upon request. The amount of tramadol used in the first 24 hours was compared as the primary endpoint. Other common side effects such as nausea, vomiting, pruritus, pain score and satisfaction score were also recorded.
Results: Data from 128 patients was analyzed. There was no difference in the amount of tramadol use, number of patients who require rescue drug, time to first dose of tramadol and percentage of patients with moderate to severe pain score between the two groups. There was a trend of less severity and episode of nausea and vomiting (20.63% vs 34.92%; p=0.09) and higher satisfaction score (4-5 vs 3-5; p=0.08) in the 0.15 group. Incidences of pruritus were not different between the two groups.
Conclusion: The dose of 0.15 mg. intrathecal morphine provides adequate post cesarean analgesia, with a trend toward less nausea, vomiting and higher satisfaction score.