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.