The aim of this study is to determine the minimum effective volume of lidocaine in 90% of patients (ED90) required for single-injection US-guided costoclavicular ICB. Determination of the minimum effective volume of LA is important because it prevents the administration of an unnecessarily large (and potentially toxic) dose. Furthermore, when multiple blocks need to be performed at the same time in the same patient, knowledge of the minimum effective volume allows to the operator to preserve efficacy without sacrificing safety for each block.