A Comparative Clinical Study of Two Different Doses of Magnesium Sulphate Added as Adjuvant to Ropivacaine 0.5% Solution for Inducing Anaesthesia with Supraclavicular Brachial Plexus Block in Patients Undergoing Upper Limb Surgery

Background and Aims: Many studies have been conducted using magnesium sulphate as adjuvant to local anaesthetics in peripheral nerve blocks, but few studies compare the effect of different doses of magnesium sulphate. We aimed at comparing the clinical profile of different doses of magnesium sulphate as adjuvant to ropivacaine in supraclavicular brachial plexus block and finding out the dose which provides maximum improvement in block parameters with minimum undesirable effects. Methods: 90 patients belonging to ASA I and II, undergoing elective upper limb surgery were randomly allocated into three groups of 30 each. Ultrasound guided Supraclavicular brachial plexus blocks were performed in each group. Group D1 (Ropivacaine 0.5% + normal saline), Group D2 (Ropivacaine 0.5% + 100 mg MgSO4), and Group D3 (Ropivacaine 0.5% + 150 mg MgSO4). Sensory and motor block onset and duration were noted. Result: The demographic profile of all patients was statistically insignificant between the three groups. Groups D2 and D3 showed a significantly faster onset (p-value <0.001) and increased duration (p-value <0.001) of sensory and motor block compared to Group D1. Intraoperative hemodynamics were comparable among the groups throughout the study period. Conclusion: We conclude that the addition of both 100 mg and 150 mg Magnesium Sulphate as adjuvant in supraclavicular brachial plexus block significantly improves block characteristics while reducing the requirement for rescue analgesia.