Effect of intra and postoperative magnesium sulphate infusion on postoperative pain

ABSTRACT

Evaluate the effect of intra and postoperative magnesium sulphate infusion on postoperative pain in abdominal surgery. Prospective double-blind randomized controlled study. Forty eight patients were randomly allocated to receive in the induction of anaesthesia, intraoperatively and six hours postoperatively either magnesium sulphate M Group [bolus 50mg/kg and 0.5g/h] or placebo [P Group]. Patients were given a dose of morphine [0.l mg/kg] IV, 45min before the end of surgery. Sedation, pain scores, cumulative morphine consumption and adverse effects were recorded up to 24 hours postoperatively. The duration of anaesthesia was similar in both groups. The time of the first demand of morphine was significantly longer in M Group then in P Group, respectively [18 +/- 5min vs 7 +/- lmin, p = 0.03]. Morphine consumption was significantly higher in control group than M group on the first postoperative day [52 +/- 4mg vs 30 +/- 3mg, p = 0.0002]. Pain scores were significantly lower in M group than in P group. Serum magnesium concentration was significantly higher in the M group. The frequency of side effects was similar in the two groups. The results of the study support magnesium sulphate as useful adjuvant for postoperative analgesia in abdominal surgery