ABSTRACT
The PA catheter (Fig. 9.1) is advanced through the right atrium, the right ventricle (RV), and the PA until a PA occlusion pressure is reached (Fig. 9.2). The static column of blood between the tip of the PA catheter and the pulmonary vein will transmit the pressure from the left atrium (LA). During diastole, when the mitral valve is open, the measured pressure also corresponds to the left ventricular diastolic pressure (Fig. 9.2). A prerequisite of a correct measurement is that the pulmonary venous pressure exceeds pulmonary alveolar pressure. This is more likely the case, when the catheter tip is directed into the lower lobe (8). The lung tissue between the tip of the catheter and the left heart results in a damping (2-4 mmHg) and delaying (100-150 milliseconds) of the pressure wave in the pulmonary capillary wedge pressure (PCWP) as compared with left ventricular or left atrial pressure (LAP) (Fig. 9.3).
