Place the patient in a supine position, with the head of the bed elevated to 45 to 90 degrees. (Normally, veins distend only when the patient lies flat.) Locate the angle of Louis (sternal notch). To do so, palpate the clavicles where they join the sternum (suprasternal notch). Place your first two fingers on the suprasternal notch. Then, without lifting them from the skin, slide them down the sternum until you feel a bony protuberance—this is the angle of Louis.

Find the internal jugular vein. Shine a flashlight across the patient's neck to create shadows that highlight his venous pulse. Be sure to distinguish jugular venous pulsations from carotid arterial pulsations: Venous pulsations disappear with light finger pressure, whereas arterial pulsations continue.

Locate the highest point along the vein where you can see pulsations. Using a centimeter ruler, measure the distance between that high point and the sternal notch. Record this finding as well as the angle at which the patient was lying. A finding greater than 3 or 4 cm above the sternal notch with the head of the bed at a 45-degree angle indicates jugular vein distention.