Bloqueo supraclavicular ecoguiado por abordaje perivascular medial. Descripción anatómica, técnica de bloqueo y cambios de perfusión regionales.

Introduction: Supraclavicular block is usually performed using a lateral to medial approach, although a medial to lateral approach is also feasible. Block onset may be evaluated through the sympathetic effect associated with the sensitive and motor blockade. Objective: To describe the ultrasound-guided supraclavicular block using a medial approach, evaluating the sensitive, motor, and sympathetic block onset. Materials and methods: An ultrasound-guided supraclavicular block was performed in a fresh cadaver with 20 mL volume (2mL of iodine and lmL of methylene blue). A CT scan was performed and sagittal sections were obtained. The clinical phase included 10 patients undergoing a medial approach block; the onset of the block was evaluated based on a motor, sensory and sympathetic assessment (measuring flow changes in the humeral artery, the palmar temperature, and the perfusion index). Results: Adequate distribution of the contrast medium was observed in the cadaver, with complete spread through the brachial plexus, both in terms of the CT-reconstruction as in the anatomical cross sections. A significant change in all the sympathetic block parameters was observed 5minutes after the bock: temperature (32.5±1.8°C to 33.4±1.7°C; P=.047), humeral arterial flow (105±70mL/min to 192±97mL/min; P = .007), and thumb perfusion index (5 ± 3 to 10 ± 3%; P = .002). The block was effective and uneventful in all patients. Conclusions: This supraclavicular approach achieves a homogeneous distribution throughout the brachial plexus, with high anesthetic efficacy. Regional changes secondary to the sympathetic block occur early after the block. [ABSTRACT FROM AUTHOR]