critical care medicine
How To Do Infraclavicular Subclavian Vein Cannulation, Ultrasound Guided
Relevant Anatomy
The subclavian vein is the proximal continuation of the axillary vein and extends medially from the lateral edge of the first rib to the brachiocephalic (innominate) vein. Because ultrasound waves do not penetrate bone, the axillary vein (distal subclavian vein) is imaged inferior to the lateral clavicle (for the infraclavicular approach). The axillary vein extends laterally from the first rib to the teres major muscle, where it becomes the brachial vein. Normal anatomic variation in the orientation of the axillary vein and artery is great, so ultrasound guidance is of particular value (and is recommended as mandatory) in this region. The axillary vessels are best identified by using a short-axis (cross-section) view in the area inferior to the distal clavicle, where the vessels are most superficial and have their largest diameter. A long-axis (longitudinal) view and shallow angle of needle insertion are useful for the axillary vein cannulation to avoid impaling the pleura. The skin insertion site is influenced by both the imaging and the dimensions of the transducer tip (ie, the skin insertion site for long-axis ultrasound guidance may be several centimeters distal to that for short-axis ultrasound guidance). Right subclavian cannulation, versus left, is sometimes preferred because it avoids the thoracic duct and because the right pleural apex is lower than the left. Left cannulation is sometimes preferred because it affords a direct, less angular path into the superior vena cava, with less chance of misdirected catheterization of the internal jugular vein. 