Inclusion Criteria:

• patients undergoing upper limb surgery at or below the elbow
• age between 18 and 75 years
• American Society of Anesthesiologists classification 1-3
• body mass index between 18 and 35 kg/m2

Exclusion Criteria:

• adults who are unable to give their own consent
• allergy or contraindication to dexmedetomidine
• exposure to dexmedetomidine during the previous 48 hrs
• pre-existing neuropathy (assessed by history and physical examination)
• coagulopathy (assessed by history and physical examination and, if deemed clinically necessary, by blood workup i.e. platelets ≤ 100, International Normalized Ratio ≥ 1.4 or partial prothrombin time ≥ 50)
• renal failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work-up i.e. creatinine. eGFR < 90)
• hepatic failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work-up i.e. transaminases ≥ 100)
• allergy to LA
• pregnancy (as institutional policy, female patients with childbearing potential undergoing non urgent surgery are tested preoperatively for pregnancy with blood tests)
• breast feeding
• prior surgery in the infraclavicular region
• chronic pain syndromes requiring opioid intake at home