Background and Aims Pain management of arthroscopic shouder day-case surgery is a real challenge. Intravenous dexamethasone and dexmedetomidine are two adjuncts to local anaesthetics used independently to prolong analgesia after peripheral nerve block, when no perineural catheter is used.

Methods This randomised, controlled, triple-blinded trial tested the hypothesis that the intravenous combination of dexamethasone and dexmedetomidine would provide superior analgesia than intravenous dexamethasone alone in patients undergoing arthroscopic rotator cuff repair with an interscalene brachial plexus block. After induction of general anaesthesia, 122 patients were randomised to receive intravenously either dexamethasone 0.15mg.kg-1 (Dexa group) or a combination of dexamethasone 0.15mg.kg-1 and dexmedetomidine 1µg.kg-1 (Dexa-Dexme group). The primary outcome was the duration of analgesia measured from the time of block procedure to first oral morphine intake. Secondary outcomes included duration of sensory and motor blocks, pains scores at rest and on movement, cumulative oral morphine consumption at 48h and rates of hypotension.

Results The mean (standard deviation) duration of analgesia was 24.5h (2.0h) in the Dexa group and 22.4h (1.6h) in the Dexa-Dexme group (p=0.42). Similarly, there were no significant differences in all the secondary outcomes, with the exception of rates of hypotension that was higher in the Dexa-Dexme group (83.3% vs 43.5%, p<0.001)

Conclusions In conclusion, the intravenous combination of dexamethasone and dexmedetomidine does not provide superior analgesia than intravenous dexamethasone after an interscalene brachial plexus block. The administration of dexmedetomidine is associated with more episodes of hypotension.