Perioperative Magnesium Sulfate Reduces Early Postoperative Pain and Analgesic Requirements Following Laparoscopic Surgery: A Randomized Controlled Trial

Abstract

Abstract
Background: Postoperative pain remains a major challenge in perioperative medicine and is associated with delayed recovery, increased morbidity, prolonged hospitalization, and reduced patient satisfaction. Magnesium sulfate (MgSO4), through N-methyl-D-aspartate receptor antagonism and modulation of calcium influx, has emerged as a potential opioid-sparing adjunct in multimodal analgesia.
Objective: To evaluate the effect of perioperative intravenous MgSO4 administration on postoperative pain intensity, analgesic requirements, and time to first analgesic request in patients undergoing laparoscopic surgery.
Materials and Methods: This prospective randomized controlled study included 350 patients undergoing elective laparoscopic surgery under standardized multimodal general anesthesia. Patients were allocated to either a control group (n = 173) or an MgSO4 group (n = 177). MgSO4 was administered as a 50 mg/kg intravenous bolus before induction, followed by continuous infusion at 15 mg/kg/h intraoperatively. Postoperative pain intensity was assessed using the verbal numerical rating scale (vNRS) at 30 minutes, 6 hours, and 24 hours postoperatively. Secondary outcomes included postoperative analgesic requirements, time to first analgesic request, incidence of postoperative nausea and vomiting (PONV), and adverse effects associated with MgSO4 administration.
Results: Patients receiving MgSO4 demonstrated significantly lower postoperative pain scores at 30 minutes (1.60 +- 0.58 vs 1.93 +- 1.21; p = 0.001) and 6 hours (1.97 +- 1.20 vs 2.31 +- 1.53; p = 0.03), whereas no significant difference was observed at 24 hours (1.54 +- 0.37 vs 1.60 +- 0.70; p = 0.4). Additional postoperative analgesia was required significantly less frequently in the MgSO4 group compared with controls (35.6% vs 64.4%; p < 0.001). Time to first analgesic request was longer in the MgSO4 group, although this did not reach statistical significance (6.95 +- 4.66 vs 5.40 +- 4.07 hours; p = 0.098). No clinically significant adverse effects related to MgSO4 administration were observed.
Conclusion: Perioperative MgSO4 administration significantly improves early postoperative analgesia and reduces postoperative analgesic requirements following laparoscopic surgery. These findings support the incorporation of MgSO4 into multimodal opioid-sparing perioperative analgesic protocols.