The Effect of Intravenous Magnesium Sulfate on Post-Operative Analgesia During Laminectomy

BACKGROUND AND OBJECTIVES Post-operative pain control is an important concern for both patients and physicians. Magnesium is being used as an adjuvant for anesthesia and analgesia during and after various surgeries. We aimed to investigate the effects of intravenous magnesium sulfate on post-operative analgesia after laminectomy. Methods Materials: In this randomized double-blind controlled clinical trial, we enrolled 40 adult patients aged 18-60 with American Society of Anesthesiologists (ASA)  Class I-II who were candidates for elective laminectomy. The patients were randomly assigned in two control groups and were similarly anesthetized. In the case group, after the induction of anesthesia, a loading dose of magnesium sulfate (30 mg/kg) was administered within five to 10 minutes followed by a maintenance dose of 10 mg/kg/hr up to the end of the surgery; while, the patients in the control group received the same volume of saline. After the surgery, all patients received a patient-controlled intravenous analgesia (PCA) pump containing morphine. The first time of using PCA, the amount of consumed morphine during the first 24 hours, and pain score were recorded at 6,12,18 and 24 hours in the post-operative period. RESULTS There was no significant difference between the two groups with respect to the amount of morphine consumed in 24 hours after the surgery (P value =0.23), the first time of using of PCA pump (P value =0.79) and pain intensity (P value=0.52). CONCLUSION The infusion of Magnesium Sulfate during laminectomy had no effect on patients' pain and opioid requirement during the first 24 hours after the surgery.