Abstract Use of a pulmonary artery catheter and cardiac output measurement Pulmonary artery catheter pressure (mm Hg)A catheter passed into the right atrium from an easily accessible central vein can be passed through the right ventricle and out into the pulmonary arterial tree while the vascular waveforms are visualized. Figure 11.1 shows the waveforms as they appear to the user. A small balloon at the tip of the catheter allows it to be flow directed and wedged in a pulmonary arterial vessel.