Magnesium sulfate improves postoperative analgesia in laparoscopic gynecologic surgeries: a double-blind randomized controlled trial.

STUDY OBJECTIVE: The aim of this study is to compare the analgesic effect of intravenous infusion of magnesium sulfate to ketorolac during laparoscopic surgeries.

DESIGN: Double-blind randomized controlled trial.

SETTING: University-affiliated teaching hospital.

PATIENTS: Sixty women submitted to laparoscopic gynecologic oncology surgeries.

INTERVENTIONS: Intravenous ketorolac 30 mg in bolus followed by saline infusion (group K), intravenous magnesium sulfate 20 mg/kg in bolus followed by magnesium 2 mg kg(-1) h(-1) (group M) or intravenous saline solution 20 mL in bolus followed by saline infusion during the entire procedure (group S).

MEASUREMENTS: Postoperative pain, nausea, vomiting, sedation, opioid consumption, time to first dose of analgesic.

MAIN RESULTS: Magnesium sulfate reduced opioid consumption compared with placebo in the postoperative, but not in the intraoperative, period. Nausea, not vomiting, was reduced in ketorolac but not in the magnesium group. Pain intensity was higher in placebo than in the other 2 groups during all periods of observation. In the first 60 minutes, pain intensity was lower in the magnesium than in the ketorolac or the placebo group.

CONCLUSION: Intraoperative magnesium sulfate improves postoperative pain control, acting as an opioid-sparing adjuvant, and is similar to ketorolac 30 mg administered in the beginning of surgery.