Cardiac output

Abstract

Numerous techniques are currently available for the measurement of cardiac output in the operating room. While the direct Fick method is often considered the gold standard, it has not been widely used in the surgical patient. With the recent widespread availability of mass spectrometry and continuous hemoglobin oximetry, it could become more popular again. The thermodilution technique is most commonly used to measure cardiac output in clinical practice, although its accuracy and reproducibility are not great. At least three consistent thermodilution determinations are required for an accurate cardiac output measurement. Errors will occur when indicator is lost or gained, while an inconsistent injection technique will produce variability in the results. New noninvasive method to measure cardiac output are very promising. They include the Doppler technique and the thoracic bioimpedance methods. In this last method, the thoracic electrical impedance is measured by sets of electrodes placed around the neck and lower thorax. The latest bioimpedance equipment incorporates new equations that have increased the accuracy of the technique.