Cardiac output monitoring

The primary goal of hemodynamic therapy is the prevention of inadequate tissue perfusion and inadequate oxygenation. Advanced cardiovascular monitoring is a prerequisite to optimize hemodynamic treatment in critically ill patients prone to cardiocirculatory failure. The most ideal cardiac output (CO) monitor should be reliable, continuous, noninvasive, operator-independent and cost-effective and should have a fast response time. Moreover, simultaneous measurement of cardiac preload enables the diagnosis of hypovolemia and hypervolemia.

Over recent years, a number of significant studies in the field of CO monitoring have been published. The available CO monitoring techniques can be divided into invasive techniques, minimally invasive techniques, and noninvasive techniques.

Minor invasive arterial thermodilution is the standard for the estimation of CO. Less invasive and continuous techniques such as pulse-contour CO and arterial waveform analysis are preferable. The accuracy of noncalibrated pulse-contour analysis is still a matter of discussion, although recent studies demonstrate acceptable accuracy compared with a standard technique. Doppler techniques are minimally invasive and offer a reasonable trend monitoring of CO. Noninvasive continuous techniques such as bioimpedance and bioreactance require further investigation.