The analgesic effect of magnesium sulfate and ketamine in patients undergoing laparoscopic cholecystectomy

In this randomized, double blind study, we investigated the analgesic effect of ketamine and magnesium sulfate in patients scheduled for laparoscopic cholecystectomy. Sixty patients were randomly assigned into three groups. Before the induction of anesthesia, Group 1 received a bolus of magnesium sulfate 50 mg/kg, and an infusion of 8 mg/kg/h for the next 4 h; Group 2 received a bolus of ketamine 0.5 mg/kg and an infusion of 0.15 mg/kg/h for the next 4 h; Group 3 received the same volume of saline solution. Intraoperative pain was treated with bolus alfentanil. Patient controlled analgesia (PCA) was used in all patients in the recovery room. Alfentanil consumptions of the Group 1 and 2 were lower than that of the Group 3 (p < 0.05). Postoperative morphine consumption of Group 2 was lower than that of the Group 3 two and three hours after surgery (p < 0.05). We conclude that addition of ketamine or magnesium sulfate to general anesthesia may decrease intraoperative analgesic requirements and administration of ketamine reduces postoperative morphine requirement. Our results indicate that a bolus of ketamine 0.5 mg/kg and subsequent infusion of 0.15 mg/kg/h is more efficient than a bolus of magnesium sulfate 50 mg/kg, and subsequent infusion of 8 mg/kg/h for postoperative pain management. © 2005 VSP.