Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 11 3 2025 02 12 298 304 Masoud Nashibi Department of Anesthesiology, Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Parisa Sezari Department of Anesthesiology, Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Kamran Mottaghi Department of Anesthesiology, Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Farhad Safari Department of Anesthesiology, Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Faranak Behnaz Department of Anesthesiology, Shohada-e-Tajrish Hospital, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Neshat Abdi Department of Anesthesiology, Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Sogol Asgari Department of Anesthesiology, Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Sara Nashibi School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2024 11 07 2024 11 30 Background: In this study, the effect of different doses of magnesium sulfate on the consumption of anesthetic drugs during surgery and pain after spine surgery has been investigated. In complex spine surgeries, a large amount of sedative and analgesic drugs is prescribed, which will have various systemic effects during and after the operation. Methods: This study was a double-blind clinical trial, and 80 patients who were candidates for posterior spinal fusion surgery at Luqman Hakim Hospital were included in the study. Patients were randomly divided into four groups (20 people in each group): Group M received magnesium sulfate in three doses (M1=10mg/kg/hr), (M2=15mg/kg/hr), and (M3=20mg/kg/hr). and group S received normal saline. Due to a drop in blood pressure and severe bradycardia in the M3 group, we had to stop the infusion, so the M3 group was excluded from the study, and 60 patients from the M1, M2, and S groups were studied. Results: The M2 group experienced a decrease in bleeding volume, intraoperative fentanyl consumption, and postoperative pain score compared to the M1 and S groups. Conclusion: In this study, we showed that the administration of magnesium sulfate during surgery can have positive and protective effects on the quality of anesthesia and the postoperative period. The recommended dose of magnesium was 15 mg/kg/hr because it has the lowest amount of narcotic consumption during the operation and the lowest amount of narcotic and analgesic consumption after the operation, and on the other hand, it has good hemodynamic stability. At the same time, doses higher than 15 mg/kg/hr are not recommended due to the drop in HR and MAP. https://aacc.tums.ac.ir/index.php/aacc/article/view/1124