Evaluation of Different Doses of Intravenous Magnesium Sulfate on Intraoperative Anesthetic Drugs Usage and Postoperative Pain in Posterior Spinal Fusion Surgery

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.