Single shot interscalene blocks are an effective analgesic for arthroscopic shoulder surgery. However, patients receiving these blocks are often found to be in significant pain when the block wears off, usually in the late evening or early hours of the morning. Overnight admission is currently routine in our unit, to ensure adequate analgesia can be administered during this period. Recent studies have suggested that adding dexamethasone to the local anaesthetic agent can prolong the duration of the block. We carried out a prospective study to assess whether addition of dexamethasone to brachial plexus blocks could reduce patient's post-operative analgesic demands and allow safe discharge on the same day after surgery.

Twenty-six patients undergoing arthroscopic shoulder surgery during a morning theatre list, had ultrasound guided brachial plexus blocks using a mixture of 0.25% bupivacaine 20–30ml with 2–3mg of dexamethasone. All were admitted to the ward afterwards for analgesia and physiotherapy. Pain numerical rating scores (0–10) were recorded at rest in recovery one hour postoperatively by the attending anaesthetist and on active movement of the shoulder joint 24 hours after surgery by the attending physiotherapist. A standardised analgesia regime was prescribed with regular and as required medication, including as required strong opiates.

Mean pain scores in recovery were 0.31 and on the morning after surgery were 2.38. Sixteen out of 26 required no further analgesia, with only 3 out of the 10 who did requiring opiates.

The use of dexamethasone provides adequate analgesia for a prolonged period for most patients after brachial plexus block for shoulder surgery and does not result in a significant analgesic requirement when the block wears off. This may provide support for avoiding overnight admission in selected patients after arthroscopic shoulder surgery.