Comparing how well arm numbness works when two anaesthetic drugs are given mixed together versus one after another, before arm and hand surgery

INTERVENTION: Intervention1: Group S sequential injection: nerve‐stimulator‐guided supraclavicular brachial plexus block. 15 mL of 2 percent lignocaine with adrenaline 1:200,000 plus dexmedetomidine 0.5 g/kg injected first, followed 60 seconds later by 15 mL of 0.75 percent ropivacaine plus dexmedetomidine 0.5 g/kg. Total volume 30 mL, total dexmedetomidine 1 g/kg. Single administration, pre‐operative. Control Intervention1: Group M Mixture injection: nerve‐stimulator‐guided supraclavicular brachial plexus block.15 mL of percent lignocaine with adrenaline 1:200,000 and 15 mL of 0.75 percent ropivacaine combined as a 1:1 mixture with dexmedetomidine 1 g/kg, injected as a single 30 mL bolus. Single administration, pre‐operative. CONDITION: Health Condition 1: O‐ Medical and Surgical PRIMARY OUTCOME: Proportion of patients with complete sensory block.pinprick score 1 in all four nerves musculocutaneous, median, radial, ulnar.Timepoint: Proportion of patients with complete sensory block.pinprick score 1 in all four nerves musculocutaneous, median, radial, ulnar. SECONDARY OUTCOME: Onset time of block. Time to complete block.Duration of analgesia.Timepoint: from completion of injection until achieved.Time to complete assessed every 2 to 5 min up to 30 min.Duration assessed Up to 24 h post block.Duration of analgesia block completion to first rescue analgesic INCLUSION CRITERIA: Patients willing to sign the informed written consent. Patients of ASA Grade I and II of either gender. Undergoing elective upper‐limb surgeries.