Effect of IV Infusion of Magnesium Sulfate on Postoperative Pain after Spinal Anesthesia: A Prospective Randomized Trial

Background: The current study attempts to evaluate the effect of intravenous (IV) infusion of magnesium sulfate during spinal anesthesia on postoperative pain and postoperative analgesic requirements in lower limb surgeries. Methods: In this double blind, randomized controlled study, 60 patients undergoing elective lower limb surgeries, were selected and randomly divided into two groups. Group I received isotonic saline and group II was administered magnesium sulfate 50 mg Kg-1 IV for 15 min and then 15 mg Kg-1 h-1 by continuous IV infusion till the end of surgery or 2 hours, whichever was earlier. Ramsay sedation scores, VAS scores for pain, time of first administration of rescue analgesic and total analgesic requirement were noted in both the groups. Results: Statistically significant difference was observed in the VAS score between the two groups at 1st, 2nd, 3rd, 6th, 9th and 12th hour intervals; with VAS scores being lower in the magnesium group (p