Comparison of efficacy of intrathecal morphine 100μg and 200μg for postoperative pain relief in patients undergoing lower abdominal and lower limb surgeries

Background: This study was designed to compare the efficacy of postoperative analgesia with intrathecal morphine in doses of 100μg, 200 μg with that of patients who received placebo (normal saline). And to compare the advantages vs. side effects between patients receiving 100 μg and 200 μg of intrathecal morphine. Patients & Methods: Sixty patients of ASA grade I and II scheduled for lower abdominal and lower limb surgeries were randomly allocated to receive either 3 ml of 0.5% hyperbaric bupivacaine with 1 ml of 0.9% normal saline (Group I n=20) or 3 ml of 0.5% hyperbaric bupivacaine with 1ml of morphine 100μg (Group II n= 20) or 3 ml of 0.5% hyperbaric bupivacaine with 1ml of morphine 200 μg (Group III n= 20) Results: Patients pulse rate, blood pressure, respiratory rate, spo₂, electrocardiogram was monitored through out the procedure and postoperatively till 24 hours. Patients were assessed for pain relief, nausea, vomiting, pruritus, sedation, urinary retention, rescue analgesia and respiratory depression. Administration of morphine intrathecally added to hyperbaric bupivacaine gives excellent postoperative analgesia which is dose dependent. 200 μg of intrathecal morphine provided excellent analgesia up to 36 hours. The incidence of nausea, vomiting and urinary retention were also dose related but with no resultant respiratory depression.