Randomized Controlled Double-Blind Study Comparing Efficacy of Two Doses of Magnesium Sulphate as an Adjuvant to Local Anesthetics in Supraclavicular Block

Abstract

Background: Magnesium sulphate (MgSO4) is one of the commonly used adjuvant in regional blocks and proved its analgesic efficacy. However, the exact dose of the drug for perineural administration is still debatable. We compared two different doses of Magnesium Sulphate (150mg and 250mg) as an adjuvant to local anesthetics in ultrasound guided supraclavicular block.
Primary objective was to compare block parameters along with postoperative analgesia duration and secondary objectives were comparison of total analgesic requirement and side effects.
Methods: 90 patients posted for elective upper limb surgeries under supraclavicular block with 12 ml 2% adrenalized lignocaine,12 ml 0.5% bupivacaine were divided in two groups. Group M1 received 150 mg and Group M2 received 250 mg magnesium sulphate.
Results: With addition of 250 mg of Magnesium, the duration of sensory (530.37 ± 67.33 min) as well as motor block (492 ± 80.52 min) was prolonged as compared to sensory (478 ± 72.6 min) and motor (442 ± 83.980 min) block durations with 150 mg. Duration of postoperative analgesia was also prolonged with 250 mg (485.33 ± 79.19 min) as compared to 150 mg (538 ± 67.2 min) respectively. Total number of postoperative analgesic doses were lesser with 250 mg magnesium.
Conclusion: Magnesium sulphate as an adjuvant in supraclavicular block in the dose 250 mg significantly prolonged the duration of sensory as well as motor block, duration of postoperative analgesia with reduction in analgesic requirement postoperatively as compared to the 150 mg with no significant side effects.