A Randomized Controlled Study of Epidural Morphine Sulfate-soaked Gelfoam and Morphine Sulfate Instillation in the Management of Postoperative Pain following Lumbar Spinal Fixation Surgery

Abstract

Abstract Background: Lumbar spinal fixation surgeries play a pivotal role in addressing pain which can be nociceptive, neuropathic, mixed, and nociplastic; however, these surgeries can also cause significant postoperative pain and discomfort, leading to prolonged hospital stays and delayed return to normal activity. Aims and Objectives: The aim of the study was to provide effective postoperative analgesia and to compare the analgesic efficacy by application of Gelfoam-soaked morphine sulfate placed in the epidural space and direct instillation of morphine sulfate in the epidural space in patients undergoing lumbar spinal fixation surgery under general anesthesia. Materials and Methods: A total of 60 patients planned for Lumbar spinal fixation surgeries were selected and sorted into two groups of 30 each after a computer-based randomization. In Group G, a 5 cm × 1 cm piece of absorbable gelatin sponge soaked in 5 mg of morphine sulfate diluted in 0.9% normal saline up to 5 mL was placed in the epidural space. In Group I, 5 mg of morphine sulfate diluted in 0.9% normal saline 5 mL was instilled over the intact epidural space. Pulse rate, mean arterial pressure (MAP), respiratory rate (RR), and peripheral oxygen saturation (SpO2) were observed hourly for the first 6 h, then at 2 hourly intervals till 12 h, and at 4 hourly intervals till 48 h. Postoperatively, pain intensity is assessed by the Visual Analog Scale (VAS) for 24 h, and the time of the first analgesic dose is noted. VAS ranges from 0 (no pain) to 10 (severe pain). Preoperative instructions were given to the patients about the use of VAS. Results: In this study, Group G demonstrated lower postoperative VAS scores and delayed need for rescue analgesia compared to Group I (P < 0.05, P < 0.0001, respectively). Group I had a higher total analgesic requirement (P < 0.0001) and consistently higher heart rates (P < 0.0001) compared to Group G. MAPs were lower in Group G compared to Group I (P < 0.0001). RRs, SpO2, sedation scores, and incidence of nausea and pruritus were similar between the two groups (P > 0.05). Conclusion: Epidural administration of morphine using Gelfoam as a vehicle for sustained release of morphine is a safe and effective method of postoperative analgesia in lumbar spinal fixation surgeries and results in better hemodynamics, prolonged duration of analgesia, and reduced requirement of rescue analgesics, compared to epidural instillation of morphine.