Ultrasonic Cardiac Output Measurement for Non- Invasive Cardiac Output Monitoring: Update and Lit- Erature Review

In this article, we review use and clinical utility of the Ultrasonic Cardiac Output Monitor, manufactured in Australia, which was first introduced clinically in 2001. It is non-invasive, requires only a low cost and allows for bedside examination, all of which make this tool potentially useful for patients in emergency departments and intensive care units. Its uses include triage, differential diagnosis of shock, resuscitation, and immediate monitoring of therapeutic intervention. According to past report, emergency physicians with no prior ultrasonographic experience can be trained to obtain reliable cardiac output estimations with the USCOM after the course of an audiovisual training package representing over 20 patients. Afterward, average intra-assessor difference in measuring cardiac output was 0.2 L/min. After reviewing the literature of the past eight years comparing measurement of cardiac output with ultrasonic measurement and Swan Ganz measurement, we found the error of cardiac output monitoring ranged from -0.01 L/min to 0.79 L/min. Thus, validity of noninvasive monitoring is still controversial. Possible factors affecting interpretation of ultrasonic data such as velocity time integral, aortic valve cross-sectional area, and operator and patient limitations are discussed.