Pulmonary artery wedge pressure (PAWP), also known as pulmonary capillary wedge pressure (PCWP), is a measure of the pressure within the pulmonary capillaries and the left atrium. It is obtained by advancing a catheter, such as a pulmonary artery catheter or a Swan-Ganz catheter, into the pulmonary artery and further into a branch of the pulmonary artery until it wedges into a small pulmonary arteriole.
PAWP is an indirect estimate of left atrial pressure and left ventricular end-diastolic pressure. It reflects the pressure exerted by the blood in the left side of the heart at the end of diastole, when the heart is relaxed and filled with blood. By measuring PAWP, clinicians can assess the filling pressures of the left side of the heart and evaluate left ventricular function.
PAWP is typically measured during a brief inflation of the balloon located at the tip of the catheter, causing it to wedge in a small vessel within the pulmonary circulation. The pressure measured at this point provides an estimation of the pressure within the left atrium.
PAWP is often used as an indicator of left ventricular preload, which is the amount of blood stretching the ventricular walls just before contraction. It helps clinicians assess the fluid status of patients, guide fluid management strategies, and evaluate the response to therapy in conditions such as heart failure or acute respiratory distress syndrome (ARDS).
Normal PAWP values typically range from 6 to 12 mmHg (millimeters of mercury), but the interpretation of PAWP readings must consider the specific clinical context and individual patient factors.
It's important to note that PAWP measurements should be interpreted along with other hemodynamic parameters, such as cardiac output, systemic vascular resistance, and arterial blood gases, to obtain a comprehensive understanding of a patient's cardiovascular status.