The pulmonary wedge pressure (PWP), also called pulmonary arterial wedge pressure (PAWP), pulmonary capillary wedge pressure (PCWP), pulmonary artery occlusion pressure (PAOP), or cross-sectional pressure, is the pressure measured by wedging a
pulmonary artery catheter
A pulmonary artery catheter (PAC), also known as a Swan-Ganz catheter or right heart catheter, is a balloon-tipped catheter that is inserted into a pulmonary artery in a procedure known as pulmonary artery catheterization or right heart cathet ...
with an inflated balloon into a small pulmonary arterial branch. It estimates the left atrial pressure.
Pulmonary venous wedge pressure (PVWP) is not synonymous with the above; PVWP has been shown to correlate with pulmonary artery pressures in studies, albeit unreliably.
Physiologically, distinctions can be drawn among pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary venous pressure and left atrial pressure, but not all of these can be measured in a clinical context.
Noninvasive estimation techniques have been proposed.
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Clinical significance
Because of the large compliance of
pulmonary circulation
The pulmonary circulation is a division of the circulatory system in all vertebrates. The circuit begins with deoxygenated blood returned from the body to the right atrium of the heart where it is pumped out from the right ventricle to the lungs ...
, it provides an indirect measure of the
left atrial pressure.
For example, it is considered the gold standard for determining the cause of
acute pulmonary edema
Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due to ...
; this is likely to be present at a PWP of >20mmHg. It has also been used to diagnose severity of left ventricular failure and mitral stenosis, given that elevated pulmonary capillary wedge pressure strongly suggests
failure of
left ventricular output.
Traditionally, it was believed that pulmonary edema with normal PWP suggested a diagnosis of
acute respiratory distress syndrome (ARDS) or non cardiogenic pulmonary edema (as in opiate poisoning). However, since capillary hydrostatic pressure exceeds wedge pressure once the balloon is deflated (to promote a gradient for forward flow), a normal wedge pressure ''cannot '' conclusively differentiate between hydrostatic pulmonary edema and ARDS.
Physiological pressure: 6–12 mm Hg.
References
External links
Overview at cvphysiology.com*
{{DEFAULTSORT:Pulmonary Wedge Pressure
Diagnostic intensive care medicine
Medical terminology
Medical tests
Cardiovascular physiology