This seeming controversy may be due to the understanding of clinicians on the potential limitations of PAC oriented RCT’s, including patient selection, timing and the general absence of a protocolized strategy based on PAC-derived variables. In spite of this the use of PAC’s is still widespread, especially in the fields of cardiology and cardiac surgery. Fuelled by large randomized controlled trials (RCT) that failed to demonstrate any outcome benefit in relation to PAC-use in a large variety of disease states, the verdict on general application in the clinical setting has become predominantly negative. Despite these noble intentions, over time the PAC has predominantly become a topic of debate concerning safety, indication and clinical utility, with the main focus on the potential of the PAC to improve clinical patient outcome. The principal stimulus for the development of the PAC was the aim to study and improve the care of acutely ill patients in whom fluoroscopy was not readily available or who were not in a condition to be readily moved to a diagnostic facility. The underlying objective of the two physicians was to apply physiologic principles to the understanding of the circulatory abnormalities characterizing an illness in an individual patient, and to provide a rational basis for selection of therapy with objective, quantitative assessment of patient response. In 1970 the floating pulmonary artery catheter (PAC) was introduced by Swan and Ganz. We conclude that thorough understanding of measurements obtained from the PAC are the first step in successful application of the PAC in daily clinical practice. Limitations of all of these measurements will be highlighted there as well. The second part will cover the measurements of the contemporary PAC including measurement of continuous cardiac output, RV ejection fraction, end-diastolic volume index, and mixed venous oxygen saturation. In this first part, the insertion techniques, interpretation of waveforms of the PAC, the interaction of waveforms with the respiratory cycle and airway pressure as well as pitfalls in waveform analysis are discussed. In this review, which consists of two parts, we will introduce the difference between intermittent pulmonary artery thermodilution using cold bolus injections, and the contemporary PAC enabling continuous measurements by using a thermal filament which at random heats up the blood. In recent years, the PAC evolved from a device that enabled intermittent cardiac output measurements in combination with static pressures to a monitoring tool that provides continuous data on cardiac output, oxygen supply and-demand balance, as well as right ventricular (RV) performance. Nowadays, the classical pulmonary artery catheter (PAC) has an almost 50-year-old history of its clinical use for hemodynamic monitoring.
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