Introduction: Interscalene brachial plexus block is an effective nerve block for shoulder and upper arm surgery. Dexmedetomidine as an additive to local anaesthetic decreases anesthetic requirement and provide prolong analgesia to patients. We designed this study to compare the effect of dexmedetomidine on duration of analgesia when added to bupivacaine in interscalene brachial plexus block.

Methods: Forty two patients undergoing upper limb surgery were randomly assigned to two groups to receive Interscalene Brachial Plexus block. They received 35 ml of 0.25% bupivacaine and either 0.2 mcg/kg body weight dexmedetomidine (Group D, n = 21) or equal volume of isotonic saline (Group B, n = 21). Sensory block onset time, sedation values, time to first analgesic requirement and any side effects were noted.

Results: Shortened sensory block onset times (113.8 sec and 334.7 sec in Group D and Group B respectively, P < 0.0001) and time to first analgesic requirement (625.90 min and 180.01 min in Group D and Group B respectively, P < 0.0001) was significantly longer in dexmedetomidine group. Conclusions: We conclude that the dexmedetomidine as an additive not only increases duration of analgesia but also decreases onset time of Interscalene brachial plexus block.