(p. 618) Pulmonary artery catheterization in the ICU 

Haemodynamic monitoring is a significant component in the management of critically-ill patients. Flow-directed pulmonary artery catheters (PAC) are a simple and rapid technique for measuring several continuous or intermittent circulatory variables. The PAC is helpful in diagnosis, guidance of therapy, and monitoring therapeutic interventions in various clinical conditions, including myocardial infarction and its complications, non-cardiogenic pulmonary oedema and severely ill patients.The catheter is inserted through a large vein. The PAC is advanced, after ballooninflation with 1.5 mL of air, through the right ventricle across the pulmonary valve and into the pulmonary artery (PA). Finally, the catheter is advanced to the ‘wedge’ position. The pulmonary artery wedge pressure (PAWP) is identified by a decrease in pressure combined with a characteristic change in the waveform. The balloon should then be deflated and the PA tracing should reappear. Direct measurements include central venous pressure, pulmonary artery pressure, and PAWP, which during diastole represents the left ventricular end-diastolic pressure and reflects left ventricular preload. Cardiac output can be measured by thermodilution technique. Other haemodynamic variables can be derived from these measurements. Absolute contraindications are rare. Relative contraindications include coagulopathy and conditions that increase the risk of arrhythmias.