Minimal Effective Volume 90% for Double-injection Costoclavicular Block

In 2020, a trial demonstrated that a 2-injection technique constitutes the optimal method for the costoclavicular block. This study aims to determine the minimum amount of medication required to achieve a successful double-injection costoclavicular nerve. Block dose assignment will be done using an up-and-down sequential method, called the Biased Coin Design (BCD). The double-injection technique for US-guided costoclavicular block consists in depositing two thirds of the LA volume in the deep compartment (to anesthetize the posterior and medial cords), and one third of the injectate in the superficial compartment (to anesthetize the lateral cord). The ED90 will be calculated using isotonic regression with a 95% confidence interval derived by bootstrapping.

Inclusion Criteria: * Age between 18 and 70 years * American Society of Anesthesiologists classification 1-3 * Body mass index between 20 and 30 Exclusion Criteria: * Adults who are unable to give their own consent * Pre-existing neuropathy (assessed by history and physical examination) * Coagulopathy (assessed by history and physical examination and, if deemed clinically necessary, by blood work up 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≥ 100) * 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 * Prior surgery in the infraclavicular region * Chronic pain syndromes requiring opioid intake at home