Continuous Measurement of Cardiac Output with an Ultrasonic Catheter

Abstract

Over the last decade the value of measuring cardiac or stroke output in the critically ill or patients undergoing major surgery has become clear and increasingly advocated (1,2). Thermal dilution via the Swan-Ganz catheter method has made cardiac output (CO) measurement a practical clinical tool. However, it suffers from a number of shortcomings, foremost of which is the fact that it is an intermittent measurement. Rapid CO changes can occur due to bleeding, surgical manipulations, induction or removal of anesthetic agents. Alteration in posture, peripheral resistance, vascular capacitance, contractility and/or intravascular volume can also occur quickly and strongly affect CO. Intermittent sampling can be misleading and during patient crises implementing CO measurement may be impossible, even though it is of value in such situations.