Retroclavicular approach vs infraclavicular approach for plexic bloc anesthesia of the upper limb: study protocol randomized controlled trial

BACKGROUND The coracoid approach is recognized as the simplest approach to perform brachial plexus anaesthesia, but needle visualization needs to be improved. With a different needle entry point, the retroclavicular approach confers a perpendicular angle between the ultrasound and the needle, which theoretically enhances needle visualization. This trial compares these two techniques. The leading hypothesis is that the retroclavicular approach is comparable to the infraclavicular coracoid approach in general aspects, but needle visualization is better with this novel approach. METHODS We designed a multicentre, randomized, non-inferiority trial. Patients eligible for the study are older than 18 years, able to consent, will undergo urgent or elective upper limb surgery distal to the elbow and are classified with American Society of Anaesthesiologists risk score (ASA) I-III. They will be excluded if they meet contraindicated criteria to regional anaesthesia, have affected anatomy of the clavicle or are pregnant. Randomization will be done by a computer-generated randomization schedule stratified for each site and in 1:1 ratio, and concealment will be maintained with opaque, sealed envelopes in a locked office. The primary outcome, the performance time, will be analyzed using non-inferiority analysis while secondary outcomes will be analyzed with superiority analysis. Needle visualization will be ranked on a Likert scale of 1-5 that is subjective and represents a pitfall. Two separate persons will rank needle visualization to compensate this pitfall. According to previous studies, 49 patients per group are required for statistical power of 0.90 and one-sided type I error of 0.05. DISCUSSION The conduct of this study will bring clear answers to our questions and, if our hypothesis is confirmed, will confer an anatomic alternative to difficult coracoid infraclavicular brachial blocks or could even become a standard for brachial plexus anaesthesia. TRIAL REGISTRATION ClinicalTrials.gov, NCT02913625 . Registered on 12 September 2016.