Jugular venous pressure


The jugular venous pressure is the indirectly observed pressure over the venous system via visualization of the internal jugular vein. It can be useful in the differentiation of different forms of heart and lung disease.
Classically three upward deflections and two downward deflections have been described.

Visualization

The patient is positioned at a 45° incline, and the filling level of the external jugular vein determined. The internal jugular vein is visualised when looking for the pulsation. In healthy people, the filling level of the jugular vein should be less than 4 centimetres vertical height above the sternal angle. A pen-light can aid in discerning the jugular filling level by providing tangential light.
The JVP is easiest to observe if one looks along the surface of the sternocleidomastoid muscle, as it is easier to appreciate the movement relative to the neck when looking from the side. Like judging the movement of an automobile from a distance, it is easier for an observer to see the movement of an automobile when it is crossing the observer's path at 90 degrees, as opposed to coming towards the observer.
Pulses in the JVP are rather hard to observe, but trained cardiologists do try to discern these as signs of the state of the right atrium.

Differentiation from the carotid pulse

The JVP and carotid pulse can be differentiated several ways:
The jugular venous pulsation has a biphasic waveform.
A classical method for quantifying the JVP was described by Borst & Molhuysen in 1952. It has since been modified in various ways. A venous arch may be used to measure the JVP more accurately.

Moodley's sign

This sign is used to determine which waveform you are viewing. Feel the radial pulse while simultaneously watching the JVP. The waveform that is seen immediately after the arterial pulsation is felt is the 'v wave' of the JVP.

Abdominojugular test

The term "hepatojugular reflux" was previously used as it was thought that compression of the liver resulted in "" of blood out of the hepatic sinusoids into the inferior vena cava, thereby elevating right atrial pressure and visualized as jugular venous distention. The exact physiologic mechanism of jugular venous distention with a positive test is much more complex and the commonly accepted term is now "abdominojugular test".
In a prospective randomized study involving 86 patients who underwent right and left cardiac catheterization, the abdominojugular test was shown to correlate best with the pulmonary arterial wedge pressure. Furthermore, patients with a positive response had lower left ventricular ejection fractions and stroke volumes, higher left ventricular filling pressure, higher mean pulmonary arterial, and higher right atrial pressures.
The abdominojugular test, when done in a standardized fashion, correlates best with the pulmonary arterial wedge pressure, and therefore, is probably a reflection of an increased central blood volume. In the absence of isolated right ventricular failure, seen in some patients with right ventricular infarction, a positive abdominojugular test suggests a pulmonary artery wedge pressure of 15 mm Hg or greater.

Interpretation

Certain wave form abnormalities, include cannon a-waves, or increased amplitude 'a' waves, are associated with AV dissociation, when the atrium is contracting against a closed tricuspid valve, or even in ventricular tachycardia. Another abnormality, "c-v waves", can be a sign of tricuspid regurgitation. The absence of 'a' waves may be seen in atrial fibrillation.
An elevated JVP is the classic sign of venous hypertension. JVP elevation can be visualized as jugular venous distension, whereby the JVP is visualized at a level of the neck that is higher than normal. The paradoxical increase of the JVP with inspiration is referred to as the Kussmaul sign, and indicates impaired filling of the right ventricle. The differential diagnosis of Kussmaul's sign includes constrictive pericarditis, restrictive cardiomyopathy, pericardial effusion, and severe right-sided heart failure.
An exaggerated "y" wave or diastolic collapse of the neck veins from constrictive pericarditis is referred to as Friedreich's sign.
An important use of the jugular venous pressure is to assess the central venous pressure in the absence of invasive measurements. A 1996 systematic review concluded that a high jugular venous pressure makes a high central venous pressure more likely, but does not significantly help confirm a low central venous pressure. The study also found that agreement between doctors on the jugular venous pressure can be poor.