Application of magnesium sulphate as a " multimodal general anesthesia" protocol in patients undergoing hysteroscopy: a randomized controlled study
Abstract Background The purpose of the study was to applicate magnesium sulphate as a " multimodal general anesthesia" protocol to reduce perioperative opioids requirements in patients undergoing hysteroscopy. Methods 70 patients scheduled for hysteroscopy were randomly divided into 2 groups. Patients in the Group M received intravenous magnesium sulfate 50 mg/kg in 100 ml of isotonic saline over 15 min before propofol injection and then 15 mg/kg per hour by continuous intravenous infusion. Patients in the control group received an equal volume of normal saline as placebo. All patients were anesthetized under a BIS guided monitored anesthesia care with propofol and fentanyl. Intraoperative anesthetic agent requirements and hemodynamic variables were recorded. Postoperative pain score was assessed with verbal numerical rating scale (VNRS) 1 min, 15 min, 30 min, 1 hour and 4 hours after recovery of consciousness. Results Postoperative serum magnesium concentrations in Group C were significantly declined than preoperative levels (0.86 ± 0.06 to 0.80 ± 0.08 mmol/L, P=0.001) while there was no statistical change in Group M (0.86 ± 0.07 to 0.89 ± 0.07 mmol/L, P=0.129). The total dose of fentanyl given to patients in Group M was less than the one administered to Group C (100 (75-150) vs 145 (75-175) μg, median (range); P < 0.001). Fewer patients in Group M required additional analgesic postoperatively. In addition, patients receiving magnesium displayed less VNRS scores at 15 min, 30 min, 1 hour and 4 hours postoperatively. Conclusions Intravenous infusion of magnesium sulphate significantly reduces perioperative opioids requirements. Meanwhile, it was beneficial to reduce postoperative pain and maintain stable of serum magnesium concentration after the procedure.