Magnesium Sulfate as a Preemptive Adjuvant to Levobupivacaine for Postoperative Analgesia in Lower Abdominal and Pelvic Surgeries under Epidural Anesthesia(Randomized Controlled Trial)

BACKGROUND: Magnesium (Mg) has been evaluated as an adjuvant to local anesthetics for prolongation of postoperative epidural and intrathecal analgesia but not with epidural levobupivacaine in lower abdominal surgeries. AIM OF THE STUDY: The aim of the study was to evaluate the preemptive analgesic effect of Mg added to epidural levobupivacaine anesthesia in infraumbilical abdominal surgeries. SETTINGS AND DESIGN: This study design was a prospective randomized controlled trial. PATIENTS AND METHODS: Two groups, each with fifty patients undergoing lower abdominal and pelvic surgeries with epidural anesthesia. Group M received 15 ml of a mixture of 14 ml levobupivacaine 0.5%, 0.5 ml magnesium sulfate 10% (50 mg), and 0.5 ml 0.9 NaCl at induction. Group L received 15 ml of 14 ml levobupivacaine 0.5% and 1 ml 0.9 NaCl at induction. Then, continuous infusion was used as 5 ml/h of the specific mixture of each group till the end of the surgery. STATISTICAL ANALYSIS: Chi-square test, unpaired t-test or Mann–Whitney, and Wilcoxon sign rank test were used. RESULTS: No statistically significant difference between the two groups regarding intraoperative hemodynamics (P > 0.05). Sensory and motor block onset was significantly shorter in Group M (14.5 [±1.51] and 12.42 [±1.69]) compared to Group L (19.86 [±1.39] and 19.34 [±1.62]) (P = 0.001). Group M showed lower visual analog scale (VAS) pain score compared to Group L from the 2(nd) to the 5(th) h postoperatively. Time for first analgesic dose was longer in Group M (294.98 [±21.67]) compared to Group L (153.96 [±10.04]) (P = 0.001). CONCLUSIONS: Preoperative and intraoperative epidural Mg infusion with levobupivacaine resulted in prolonged postoperative analgesia and lower VAS.