According to this study:

* Visualization of the external jugular vein can provide a reliable estimate of central venous pressure.

The assessment of central venous pressure (CVP) provides information important to managing critically ill patients, but examination of the internal jugular vein for that purpose is often difficult.

Researchers performed a prospective, blinded study to compare the usefulness of the external jugular vein in the assessment of CVP, with the measurement of CVP using an indwelling central venous catheter. Clinicians performed blinded examinations of the external jugular vein to estimate CVP, categorized as either low (5 cm or less of water) or high (10 cm or more of water), and researchers assessed the examination's usefulness in distinguishing low CVP from high CVP. After 118 examinations in 35 patients were recorded and analyzed the researchers reported that the external jugular vein was easier to visualize than the internal jugular vein and that such visualization reliably identifies abnormally low or high CVP with remarkable precision. This may have important clinical implications: the measurement of CVP allows clinicians to determine the cause of dyspnea, the reason for pulmonary edema (low versus high CVP), and intravascular volume in a hypotensive patient; CVP is also an important clinical marker in the resuscitation of patients who have severe sepsis and are in septic shock.