Comparison of Magnesium Sulfate and Dexmedetomidine as an Adjuvant to 0.5% Ropivacaine in Peripheral Nerve Stimulator-guided Supraclavicular Block for Upper Limb Surgery

Background: The most promising technique that emerged in orthopedic surgery with plentiful advantages was the supraclavicular brachial plexus nerve block (SCBPB). It was a peripheral nerve stimulator-guided technique that helped us reinforce accurate nerve targeting, which extended the duration of the block. Dexmedetomidine offers a prolonged duration of analgesia compared to magnesium sulfate (MgSO 4 ), which exhibits the fastest duration of sensory and motor block. Materials and Methods: This present prospective, randomized, single-blind comparative study includes 120 participants who were scheduled for upper limb surgery and categorized according to the American Society of Anesthesiologists grade. Pain intensity was measured using the Visual Analog Scale score. Results: Demographic data show no significant difference among the groups. Group M showed the fastest onset (motor: 9.12 min and sensory: 9.26 min), followed by Group D (motor: 11.72 min and sensory: 14.18 min), with Group R being the slowest (both around 19 min) ( P < 0.0001). For block duration, Group D had the longest effect (motor: 12.18 h and sensory: 12.28 h), followed by Group M (motor: 10 h, sensory: 10.14 h), while Group R was the shortest (motor: 5.97 h and sensory: 6.03 h) ( P < 0.0001). Group D consistently had the lowest pain scores at 6, 9, and 12 h, showing significant differences compared to Group R and Group M ( P < 0.0001). Conclusion: Dexmedetomidine provides a prolonged duration of analgesia compared to MgSO 4 . However, it has been associated with several adverse effects, demonstrating the need for further research. Ultimately, this will reduce the rate of adverse effects and accelerate the use of analgesia.