Jugular Venous Pressure (JVP). Estimating the JVP is one of the most iportant and frequently used skills of physical examination. At first it will seem ficult, but with practice and supervision you will find that the JVP provides aluable information about the patient's volume status and cardiac function.
you have learned, the JVP reflects pressure in the right atrium, or central venous pressure, and is best assessed from pulsations in the right internal jugular vein. Note, however, that the jugular veins and pulsations are difficult to see in children younger than 12 years of age, so they are not useful for evaluating the cardiovascular system in this age group (see Chapter 17, pp. - ).
To assist you in learning this portion of the cardiac examination, steps for assessing the JVP are outlined on the next page. As you begin your assessment, take a moment to reflect on the patient's volume status and consider how you may need to alter the elevation of the head of the bed or examin-
ing table. The usual starting point for assessing the JVP is to elevate the head of the bed to 30°. Identify the external jugular vein on each side, then find the internal jugular venous pulsations transmitted from deep in the neck to the overlying soft tissues. The JVP is the elevation at which the highest oscillation point, or meniscus, of the jugular venous pulsations is usually evident in euvolemic patients. In patients who are hypovolemic, you may anticipate that the JVP will be low, causing you to subsequently lower the head of the bed, sometimes even to 0°, to see the point of oscillation best. Likewise, in volume-overloaded or hypervolemic patients, you may anticipate that the JVP will be high, causing you to subsequently raise the head of the bed.
A hypovolemic patient may have to lie flat before you see the veins. In contrast, when jugular venous pressure is increased, an elevation up to 60° or even 90° may be required. In all these positions, the sternal angle usually remains about 5 cm above the right atrium, as diagrammed on p._.
STEPS FOR ASSESSING THE JUGULAR VENOUS PRESSURE (JVP)
■ Make the patient comfortable. Raise the head slightly on a pillow to relax the sternomastoid muscles.
■ Raise the head of the bed or examining table to about 30°. Turn the patient's head slightly away from the side you are inspecting.
■ Use tangential lighting and examine both sides of the neck. Identify the external jugular vein on each side, then find the internal jugular venous pulsations.
■ If necessary, raise or lower the head of the bed until you can see the oscillation point or meniscus of the internal jugular venous pulsations in the lower half of the neck.
■ Focus on the right internal jugular vein. Look for pulsations in the suprasternal notch, between the attachments of the sternomastoid muscle on the sternum and clavicle, or just posterior to the sternomastoid. The table below helps you distinguish internal jugular pulsations from those of the carotid artery.
■ Identify the highest point of pulsation in the right internal jugular vein. Extend a long rectangular object or card horizontally from this point and a centimeter ruler vertically from the sternal angle, making an exact right angle. Measure the vertical distance in centimeters above the sternal angle where the horizontal object crosses the ruler. This distance, measured in centimeters above the sternal angle or the atrium, is the JVP.
The following features help to distinguish jugular from carotid artery pulsations:
Internal Jugular Pulsations
Soft, rapid, undulating quality, usually with two elevations and two troughs per heart beat
Pulsations eliminated by light pressure on the vein(s) just above the sternal end of the clavicle
Level of the pulsations changes with position, dropping as the patient becomes more upright.
Level of the pulsations usually descends with inspiration.
A more vigorous thrust with a single outward component
Pulsations not eliminated by this pressure
Level of the pulsations unchanged by position
Establishing the true vertical and horizontal lines to measure the JVP is difficult, much like the problem of hanging a picture straight when you are close to it. Place your ruler on the sternal angle and line it up with something in the room that you know to be vertical. Then place a card or rectangular object at an exact right angle to the ruler. This constitutes your horizontal line. Move it up or down—still horizontal—so that the lower edge rests at the top of the jugular pulsations, and read the vertical distance on the ruler. Round your measurement off to the nearest centimeter.
Increased pressure suggests right-sided heart failure or, less commonly, constrictive pericarditis, tricuspid stenosis, or superior vena cava obstruction.
In patients with obstructive lung disease, venous pressure may appear elevated on expiration only; the veins collapse on inspiration. This finding does not indicate congestive heart failure.
Venous pressure measured at greater than 3 cm or possibly 4 cm above the sternal angle, or more than 8 cm or 9 cm in total distance above the right atrium, is considered elevated above normal.
If you are unable to see pulsations in the internal jugular veins, look for them in the external jugulars, although they may not be visible here. If you see none, use the point above which the external jugular veins appear to collapse. Make this observation on each side of the neck. Measure the vertical distance of this point from the sternal angle.
Th e highest point of venous pulsations may lie below the level of the sternal angle. Under these circumstances, venous pressure is not elevated and seldom needs to be measured.
Even though students may not see clinicians making these measurements very frequently in clinical settings, practicing exact techniques for measuring the JVP is important. Eventually, with experience, clinicians and cardiologists come to identify the JVP and estimate its height visually.
Jugular Venous Pulsations. Observe the amplitude and timing of the jugular venous pulsations. In order to time these pulsations, feel the left carotid artery with your right thumb or listen to the heart simultaneously.
Unilateral distention of the external jugular vein is usually due to local kinking or obstruction. Occasionally, even bilateral distention has a local cause.
Prominent a waves indicate increased resistance to right atrial contraction, as in tricuspid stenosis
The a wave just precedes S1 and the carotid pulse, the x descent can be seen as a systolic collapse, the v wave almost coincides with S2, and the y descent follows early in diastole. Look for absent or unusually prominent waves.
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