A Comparison of the Effects of Epidural Levobupivacaine and Morphine for Postoperative Analgesia Following Major Abdominal Surgery: A Randomized Controlled Trial

Objectives Epidural analgesia remains the cornerstone of pain management following laparotomy. Local anesthetics used in epidural analgesia provide good analgesia but may result in hypotension and/or motor blockade. Morphine, a long-acting opioid, can also be used epidurally to provide analgesia. Morphine used epidurally will cause fewer hemodynamic disturbances and no motor blockade. Hence, we compared the efficacy, hemodynamic parameters, and motor blockade between epidural levobupivacaine and morphine for postoperative analgesia following laparotomy. Materials and methods This is a prospective, double-blind, randomized controlled study registered in the Clinical Trials Registry of India (CTRI/2021/04/033102). Ninety patients undergoing elective major abdominal surgery were randomly divided into two groups: levobupivacaine (0.125%/mL) and morphine (0.032 mg/mL) group. All patients received epidural infusion at 6 mL/hour. The visual analog scale (VAS) score at rest and during cough was observed for 24 hours. Heart rate and blood pressure were monitored continuously for 24 hours postoperatively. Additional analgesic requirements, postoperative sedation score, and motor blockade were also compared between the two groups. Statistical analysis was done using the chi-square test, unpaired T-test, and Mann-Whitney test. The sample size estimation was based on a pilot study. Results The demographic data and duration of the procedure were comparable in both groups. The initial median VAS score at rest in the levobupivacaine group was high (interquartile range (IQR): 2-4) when compared to the morphine group (IQR: 1-3) at the fourth, sixth, and eighth hour with a P value of <0.05. The initial median VAS score at coughing in the levobupivacaine group was 4 (IQR: 3-5) and in the morphine group was 3 (IQR: 3-4). The VAS score at rest and at coughing was significantly higher in the levobupivacaine group. Heart rate was stable in both groups, and a significant fall in mean arterial blood pressure was observed in the levobupivacaine group. The sedation score was significantly higher in the morphine group (IQR: 2-2) when compared to the levobupivacaine group (IQR: 1-2) at the fourth hour postoperatively with a P value of <0.05. Motor blockade was found to be stronger in the levobupivacaine group (IQR: 0-2) when compared to the morphine group (IQR: 0-0) at the fourth, sixth, and eighth hour postoperatively with a P value of <0.05. An additional dose of fentanyl was required by 6.7% of the patients in the levobupivacaine group and 8.9% of the patients in the morphine group. In the levobupivacaine group, 11.1% reported headaches, 2.2% reported vomiting, and 4.4% reported hypotension, and no pruritus was reported. In the morphine group, 11.1% reported tachycardia, 6.7% reported nausea and vomiting, 6.4% reported pruritus, and 2.2% reported hypotension. Conclusion We conclude that patients receiving epidural morphine had better pain scores with better hemodynamic stability than the epidural levobupivacaine group following laparotomy. The morphine group had less motor blockade. Sedation was observed in the morphine group. Additional analgesics were required in both groups. The adverse effects observed in the epidural morphine group were tachycardia, nausea, pruritus, and itching. The epidural levobupivacaine group reported headache, vomiting and fever, and hypotension.