Erroneous interpretation of pulmonary capillary wedge pressure in massive pulmonary embolism

Pulmonary capillary wedge pressure (WP) values obtained after catheterization of a pulmonary artery (PA) totally occluded by thrombus may be erroneously interpreted. The left lower lobe PA was catheterized in 13 anesthetized dogs. Measurements of mean pulmonary artery pressure (MPAP) and WP were performed before and after total occlusion of the PA by a clamp located 1 cm from the tip of the catheter. There was a difference between pulmonary artery occluded pressure (PAoP), MPAP, and WP, both in normovolemic and overload conditions (p less than .01). The PAoP was not equivalent either to WP or to MPAP. In massive pulmonary embolism, WP may not reflect left ventricular end-diastolic pressure (LVEDP).