Venous Pressure By Jugular Inspection

1. With which chambers of the heart are the jugular veins in continuity in systole and in diastole?

ANS: In systole the jugular veins are in continuity only with the right atrium, because the tricuspid valve is closed. In diastole, when the tricuspid valve is open, the jugulars are also in continuity with the right ventricle (RV). Therefore, examination of the jugulars may reveal the contour and pressure in the right atrium and RV without the need for catheterization.

In diastole, the atrium and ventricle are in continuity and become an "atrioventricle." Note also that the internal jugulars are in a more direct line with the superior vena cava than are the external jugulars.

In diastole, the atrium and ventricle are in continuity and become an "atrioventricle." Note also that the internal jugulars are in a more direct line with the superior vena cava than are the external jugulars.

Jugular Right Ventricle

External IJ J jugulars

Ventricular systole

External IJ J jugulars

Diastole

Ventricular systole

Diastole

2. Why is the internal jugular a more accurate manometer than the externals?

ANS: a. The internal jugulars are in a direct straight-line communication with the superior vena cave which, in turn, communicates directly with the right atrium. The external jugulars communicate with the superior vena cave after two near 90° turns, one where the external jugular enters the subclavian and another where the subclavian enters the superior vena cava. It is only logical that it would be difficult to communicate pressure accurately through two sharp turns.

b. The external jugulars are occasionally either absent or too thready to be visible to the naked eye in the normal population.

c. If the external jugulars are narrow in diameter under normal conditions, they become so constricted with heart failure or shock due to the increased sympathetic stimulation that they may become invisible.

3. When do internal jugulars become visible?

ANS: Only in the presence of severe tricuspid regurgitation.

4. If the internal jugulars are usually invisible, how can they be used as a manometer to measure venous pressure?

ANS: The pulsations of the internal jugulars are transmitted to the skin of the neck. The top level of the skin's pulsations is taken as the venous pressure. Thus the jugular is used as a "pulsation manometer."

5. Which is the most accurate internal jugular to use, the left or the right? Why?

ANS: Normally, the pressure in the right jugulars is either slightly greater than or the same as that in the left jugulars. Upper levels of normal have been established for the right side. In some arteriosclerotic patients the left jugular pressure may be falsely elevated owing to compression of the innominate vein between the sternum anteriorly and large tortuous arteries arising from a high unfolded aortic arch posteriorly. (An aortic aneurysm may also be the cause of innominate vein compression, but this is rare in comparison with arteriosclerotic compression.)

6. What does the expression, "The jugulars were (or were not) distended," imply?

ANS: This expression denotes several things:

a. The physician was using the external jugulars and therefore the absolute height of the venous pressure will be inaccurate. The external jugular top level of pulsations is usually lower than the top level of the internal jugulars.

b. When the statement is made that the jugulars were "flat" or "not distended," the internal jugular pulsations may still be very high if the external jugulars are either congenitally invisible or too constricted by the sympathetic stimulation of heart failure to be seen.

c. If the statement is made that the jugulars were distended to a high level with the chest elevated to 45° then you can probably believe that the venous pressure is actually high. This is because internal jugulars are almost always higher than external jugulars.

Boldface type indicates that the term is explained in the glossary.

7. When may you use external jugulars to measure venous pressure?

ANS: a. It is helpful to apply supraclavicular pressure with the chest elevated to 45° in an attempt to raise external jugulars when first looking at the neck for venous pressure. If the externals were invisible before supraclavicular pressure and can be distended by supraclavicular pressure, then they have a normal pressure and give a strong indication that the internal jugular pressures are also normal. b. In severe TR the RV systolic pressure transmits poorly to the external jugulars, which will more accurately reflect venous pressure.

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