Implementation of magnesium sulphate as an adjunct to multimodal analgesic approach for perioperative pain control in lumbar laminectomy surgery: A randomized placebo-controlled clinical trial.

Objective: To investigate the effect of systemic intraoperative administration of magnesium sulphate when used in the context of a multimodal pain management plan on analgesics consumption and pain scores, and perioperative outcomes after lumbar laminectomy surgery.

Methods: Seventy-four patients undergoing lumbar laminectomy were enrolled in this randomized, double-blind, placebo-controlled trial. Participants were randomly allocated to receive magnesium (20 mg/kg iv given as bolus before anesthesia induction followed by 20 mg/kg/h civ until surgery completion) or saline. Hemodynamic variables and desflurane consumption were noted at predefined time-intervals intraoperatively. Primary outcome was postoperative cumulative analgesic consumption over 24 h, while pain intensity (assessed by Visual Analogue Scale [VAS] at 1, 2, 4, 6 and 24 h), intraoperative hemodynamics and opioid requirements, recovery profile, time to first analgesic request, and adverse effects constituted secondary end-points.

Results: Demographics, surgery duration, desflurane requirements, and recovery profile were comparable between groups. Magnesium attenuated hemodynamic response during incision and emergence from anesthesia. Postoperative analgesics consumption in morphine iv equivalents (mean difference -9.24 [95 %CI -13.31, -5.17] mg; p = 0.001) and VAS scores at all-time points of assessment were lower in magnesium group; this effect peaked at 4 h (mean difference -2.15 [95 %CI -3.21,-1.09; p = 0.001]. Magnesium reduced intraoperative remifentanil consumption and prolonged the time-interval to first rescue analgesia (p < 0.01). No notable adverse effects were recorded.

Conclusion: It occurs that magnesium infusion during lumbar laminectomy surgery potentiates perioperative analgesia and reduces analgesic requirements up to 24 h postoperatively. No profound adverse effect on either intraoperative hemodynamics or any other clinically relevant endpoints becomes evident.