Methods of Cardiac Output Monitoring

Abstract

Cardiac output is the primary compensatory mechanism that responds to an oxygenation challenge. The determination of blood flow, i.e. cardiac output, is an integral part of hemodynamic monitoring. This is a review on methods of cardiac output monitoring. Minimally invasive cardiac output monitors have varying degrees of ‘invasiveness’ with some being totally non-invasive and others only marginally less invasive than a pulmonary artery catheter (PAC). All minimally invasive cardiac output monitors have their own sources of potential error. Users of cardiac output monitors should be aware of their potential sources of error and clinical limitations. There are many methods of monitoring the hemodynamic status of patients, both invasive and non-invasive, the most popular of which is thermodilution. The invasive methods are the Thermodilution and Fick method, whereas the non-invasive methods are transoesophageal echocardiography, oeshophaegeal Doppler, pulse contour, lithium dilution, and partial CO2 rebreathing and thoracic electrical bioimpedance. All the methods have their advantages and disadvantages, but thermodilution is the golden standard for critical patients, although it does many risks. But, the thermodilution technique remains the most common approach in use today.