Intraperitoneal Instillation of Magnesium Sulphate vs Bupivacaine for Post-Operative Analgesia following Laparoscopic Cholecystectomy

Background: Postoperative pain following laparoscopic cholecystectomy, though less severe than open procedures, remains clinically significant due to its multifactorial origin involving somatic, visceral, and referred components. Intraperitoneal instillation of analgesic agents has emerged as an effective strategy to target visceral nociception while minimizing systemic opioid-related adverse effects. Magnesium sulphate, an N-methyl-D-aspartate (NMDA) receptor antagonist, has shown promise as an adjuvant analgesic due to its anti-nociceptive and opioid-sparing properties. The aim and objective is to evaluate and compare the analgesic efficacy of intraperitoneal instillation of magnesium sulphate versus bupivacaine in patients undergoing elective laparoscopic cholecystectomy. Material and Methods: The present study was a randomized clinical study, in which 105 patients of age 18-60 years, belonging to American Society of Anaesthesiologists (ASA) grade I or II, for laparoscopic cholecystectomy were randomly selected and divided into three groups of 35 patients each: Group B received 30 ml of 0.25% Bupivacaine, Group M received 30 mL of mixture of 50mg/kg MgSO4 and (0.9%) NS, Group C received 30 ml of (0.9%) NS Intraperitoneally. Visual Analog Scale (VAS) score as primary outcome, recorded for 24 hours after surgery. Secondary outcomes included time to first rescue analgesia, total dose requirements of rescue analgesia, and adverse events. Results: The VAS Score was significantly lower in group B as compared to group M and group C. The average Time to 1st dose of post-operative analgesia demand was also the longest in Group B compared to Group M and Group C (7.38±1.01 hours compared to 5.23±0.92 hours and 2.5±1.12 hours respectively) which was also highly significant. Total rescue analgesic requests in group B was significantly lower than that in the group M and group C (P-value ˂0.05), with no significant difference observed between the group M and group C. Neither drug caused a significant difference in the incidence of postoperative nausea and vomiting (P-value ˃ 0.05). Conclusion: Intraperitoneal instillation of both magnesium sulphate and bupivacaine are effective for postoperative pain management following laparoscopic cholecystectomy. But intraperitoneal instillation of bupivacaine was found to be superior for postoperative analgesia in first 24 hours after laparoscopic cholecystectomy as reflected by a lower VAS score and longer duration of analgesia.

Keywords: Laparoscopic cholecystectomy, intraperitoneal analgesia, magnesium sulphate, bupivacaine, postoperative pain, multimodal analgesia.