The goal of the study is to compare the duration of analgesia in patients undergoing forearm or hand surgery with a supraclavicular brachial plexus block, who receive either iv dexmedetomidine or placebo.

Most surgical interventions on the forearm and the hand in Valais Hospital are performed under regional anesthesia. This ensures intraoperative patient comfort and reduces pain during the first 6 to 12 postoperative hours. A very common strategy to provide anesthesia of the arm is to inject local anesthetics in the region over the clavicle around the brachial plexus. This "supraclavicular brachial plexus block" is routinely performed in Valais Hospital and is always done under ultrasound guidance.

A drawback of locoregional anesthesia is the recurrence of pain once the effect of the block wears off after approximately 6 to 8 hours. This phenomenon is called rebound pain. It and can be very severe and debilitating, can significantly impact postoperative recovery and may also preclude ambulatory surgery as well as early mobilization and physiotherapy. Therefore, strategies that prolong the analgesic effect of locoregional anesthesia are warranted.

Dexmedetomidine is a selective α2-adrenoceptor agonists with sedative and analgesic properties. It has been shown to prolong the analgesic duration of local anesthetics when administered intravenously. However, the association of dexmedetomidine with long-acting local anesthetics for supraclavicular brachial plexus block has not been systematically investigated.

Inclusion Criteria:

Patients undergoing elbow, forearm or hand surgery under supraclavicular brachial plexus block Patients who are ASA physical status I-III

Exclusion criteria

• Patient refusal
• ASA physical status IV
• History of hypersensitivity or intolerance to dexmedetomidine
• History of hypersensitivity or intolerance to dexamethasone
• History of hypersensitivity or intolerance to local anesthetics
• History of recent (< 1 year) cerebrovascular insult
• Second or third degree heart block
• Uncontrolled hypotension
• Conditions contraindicating supraclavicular brachial plexus block: neurological deficit or neuropathy of the arm, severe hepatic dysfunction (Child B and C), coagulopathy, malignancy or infection in the area above the clavicle
• Chronic opioid use
• Pregnancy

dexmedetomidine or placebo prepared by Lausanne University Hospital Pharmacy