What measurement is taken at the distal tip of a PA catheter?

The wedge pressure measurement is specifically taken at the distal tip of a pulmonary artery (PA) catheter when the balloon at the tip is inflated. This procedure allows the catheter to be "wedged" into a small pulmonary artery, occluding it temporarily. By doing so, it reflects the pressure in the left atrium, providing valuable information about left ventricular function and fluid status in critically ill patients. This measurement is particularly useful in assessing conditions such as heart failure, pulmonary congestion, and fluid responsiveness.

In contrast, the other measurements listed are associated with different locations or functions of the PA catheter. Central venous pressure is measured using a separate catheter placed in the superior vena cava or the right atrium, while right ventricular pressure is obtained directly from the right ventricle when the catheter is placed in that chamber. Pulmonary artery pressure is recorded without occlusion from the distal tip of the catheter when the balloon is not inflated. Thus, wedge pressure is unique to the PA catheter's wedge technique and offers insights into the hemodynamic status of the left heart.