Efficacy of Magnesium Sulfate and Dexmedetomidine as Adjuvants to Ropivacaine in Supraclavicular Brachial Plexus Block: A Randomised Clinical Study

Introduction: Peripheral nerve blocks have recently proven to be extremely promising in terms of patient satisfaction. In upper limb procedures, rapid and deep anaesthesia can be achieved with supraclavicular ultrasound-guided access to the brachial plexus. To improve the quality of local anaesthesia, adjuvants such as magnesium sulfate and dexmedetomidine have been added to the local anaesthetic. Aim: To evaluate the efficacy of magnesium sulfate and dexmedetomidine as adjuvants to ropivacaine in supraclavicular Brachial Plexus Blockade (BPB). Materials and Methods: A prospective randomised double-blind study was conducted in the Department of Anaesthesiology from June 2016 to November 2017 ( 1 year and 6 months) at King George's Medical University, Lucknow, Uttar Pradesh, India. A total of 60 patients were divided into two groups using a computer -generated random number for upper limb surgeries (below the mid-humerus) under supraclavicular brachial plexus block. Group A (n=30) received ropivacaine 0.5% (30 mL) plus dexmedetomidine 50 pg for the supraclavicular block, and Group B received ropivacaine 0.5% (30 mL) plus magnesium sulfate 150 mg in 1 mL Normal Saline (NS) 0.9% for the same block. A comparison of these two groups was conducted for the time of onset, duration of sensory and motor block, haemodynamic stability, postoperative analgesia, and complications. Statistical analyses such as Student's t -test, Chi-square test, and Mann-Whitney U-test were used. Results: The mean age of Group A was 28.03 +/- 5.86 years and Group B was 31.07 +/- 7.06 years. The sensory block and motor block onset were significantly faster among patients of Group A (6.47 +/- 1.43 min and 8.50 +/- 1.46 min) compared to Group B (9.57 +/- 1.22 min and 11.77 +/- 1.19 min). The mean duration of analgesia was significantly longer (p<0.001) in Group A (1034.10 +/- 61.07 min) compared to Group B (460.00 +/- 35.82 min). The duration of sensory block and motor block was also significantly higher (p<0.001) in Group A compared to Group B. Both groups were haemodynamically stable, but sedation was significantly higher in Group A. Conclusion: Dexmedetomidine 50 pg is a superior adjuvant compared to magnesium sulfate 150 mg with ropivacaine 0.5% in supraclavicular brachial plexus block as it significantly hastens onset time and prolongs the duration of sensory and motor blocks and the duration of analgesia.