To estimate the level of the JVP, learn to find the highest point of oscillation in the internal jugular vein or, alternatively, the point above which the external jugular vein appears collapsed. The JVP is usually measured in vertical distance above the sternal angle (also called the angle of Louis), the bony ridge adjacent to the second rib where the manubrium joins the body of the sternum.
Study carefully the illustrations in Figure 1. Note that in the three positions, the sternal angle remains roughly 5 cm above the right midatrium. In this patient, the pressure in the internal jugular vein is somewhat elevated.
FIGURE 1. JVP height remains relatively constant.
In Position A, the head of the bed is raised to the usual level, approximately 30°, but the JVP cannot be measured because the level of oscillation, or meniscus, is above the jaw and, therefore, not visible.
■ In Position B, the head of the bed is raised to 60°. The "top" of the internal jugular vein is now easily visible, so the vertical distance from the sternal angle or right atrium can now be measured.
■ In Position C, the patient is upright and the veins are barely discernible above the clavicle, making measurement untenable.
Note that the height of the venous pressure as measured from the sternal angle is similar in all three positions, but your ability to measure the height of the column of venous blood, or JVP, differs according to how you position the patient. JVP measured at >3 cm above the sternal angle, or >8 cm above the right atrium, is considered elevated or abnormal.
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