critical care medicine
How To Do Infraclavicular Subclavian Vein Cannulation
Relevant Anatomy
Superiorly overlying the first rib, in sequence from anterior to posterior, are the clavicle, subclavian vein, anterior scalene muscle, and subclavian artery. Just medial to the junction of the medial and middle thirds of the clavicle, the subclavian vein is attached by fibrous tissue to both the first rib and the clavicle, stabilizing its position and diameter. At this site, the size of the subclavian vein is only slightly affected by respiration, the Trendelenburg position, or the Valsalva maneuver. This region of the vein is the intended target of subclavian venipuncture using the infraclavicular approach. The infraclavicular approach is most common, and one of two skin insertion sites is used: either 1 to 2 cm inferior to the clavicle at the junction of its medial and middle thirds, or just inferior to the clavicle at its midpoint. Needles are advanced medially along a coronal (frontal) plane—skirting beneath the clavicle—toward the sternal notch. At the first site, the underlying first rib offers protection against pneumothorax. At the second site (clavicular midpoint), less effort is needed to maintain the shallow angle of insertion that keeps the needle in the coronal plane. 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 (especially for pulmonary arterial catheterization) because it affords a direct, less angular path to the superior vena cava, with less chance of misdirected catheterization of the internal jugular vein. 