Figure 5.

Sonographic guidance of central venous cannulation. (A) Transverse view of the anterior neck. The internal jugular vein (V) is underneath the sternocleidomastoid muscle (SCM). The carotid artery (arrow) is posterior and medial to the vein, and it is positioned outside the path of a needle into the center of the vein. Right panel shows the collapse of the vein, but not the artery, with compression. (B) The needle should be offset from the probe and at an angle such that (right) it enters the vein within the sound beam.