Background and Aims This study was conducted to determine the role of dexmedetomidine (DEX) as an adjuvant in reducing the efficient dose of bupivacaine in supraclavicular block.

Methods A prospective study, including 40 patients ASA I and ASA II undergoing upper limb and hand surgery, who were randomly divided into 2 groups; group D received the fixed dose of 100 µg of dexmedetomidine (1 ml) added to a predefined dose of bupivacaine 0.25%; Group S received bupivacaine 0.25% with 1 ml of normal saline (NS).Starting with the dose of 30 ml of bupivacaine 0.25%. The dose was reduced by 3 ml every time the block was a success. the onset time of the block at 30 min at most defined as the success criteria. The minimal dose required to have a sensory and a motor block in each group was compared. Onset time and duration of sensory and motor blockage, as well as side effects were also studied.

Results The addition of 100µg of DEX did not reduce the minimum efficient dose of bupivacaine. Tis dose was 17 ml in GD versus 18 ml in GS, to have 50% of successful supraclavicular bloc [ED50].

We noted a prolonged blockage duration without a reduction in the onset time in GD, with no statistical difference between the two groups.

We noted complications in the GD only, 2 cases of bradycardia, 2 of Claude Bernard Horner and one case of hypotension. But no statistical difference between the two groups.

Conclusions To have 50% of successful supraclavicular bloc [ED50].