Minimally Invasive Cardiac Output Monitoring: Toy Or Tool?

Abstract

Cardiac output measurement is still regarded as one of the key hemodynamic variables in the assessment of cardiac function and as an essential measure for guiding the therapy of critically ill patients. In order to achieve adequate oxygen delivery (DO₂), hemodynamic monitoring is necessary in order to provide appropriate cardiovascular support [1]. Although measurements of regional perfusion and oxygenation are gaining increasing attention, cardiac output measurement is still regarded as the key hemodynamic variable in the assessment of cardiac function and to guide therapy. Flow, as gauged by cardiac output, is the key measure of how well the circulation is delivering oxygen and nutrients to the vital organs and is the focus of all resuscitation efforts. Traditionally a pulmonary artery catheter (PAC) has been used for measuring pulmonary arterial pressures and cardiac output by thermodilution techniques in order to guide fluid therapy and hemodynamic manipulation. There have been serious concerns about the risk-benefit ratio of using pulmonary artery occlusion pressure (PAOP) as a measure of cardiac preload and recent studies have suggested a lack of benefit in some patient groups using the PAC [2]72-[4]. Recently, in a cohort of patients undergoing major non-cardiac surgery, it was demonstrated that the use of the PAC provides no benefit [5]. Among patients with severe sepsis, PAC placement was not associated with a change in mortality rate or resource use, although small non-significant trends towards a lower resource use were present in the PAC group [6]. In a consensus statement of the National Heart, Lung, and Blood Institute (NHLBI) and the Food and Drug Administration (FDA) PAC use was not recommended for elective major surgery [7].