Pulmonary artery catheter commonly used to assess hemodynamic status of cardiovascular system. Placement is through Cordis catheter in internal jugular or subclavian veins; after tip is advanced to 20 cm, balloon is inflated with 2Ð3 ml of air, and catheter is slowly advanced through right atrium and into pulmonary vein, with characteristic waveforms given off at each location. Catheter is then slowly advanced further until inflated balloon becomes ÒwedgedÓ into branch of pulmonary artery, with obliteration of pulmonary artery waveform. Once correctly positioned, preload status (central venous pressure), cardiac contractility (cardiac output and index), and afterload status (systemic vascular resistance) can be determined. Balloon must always be deflated when in place if readings are not being taken.