Hydraulic Bench Testing of the TruCATH~(TM)/TruCCOM~(TM) Continuous Cardiac Output Monitor

摘要

The aim of this study was to test the truCATH~(TM)/ truCOMMS~(TM) continuous cardiac output catheter/monitor in a computer-controlled pulsatile mock loop system. The pulmonary artery catheter is equipped with two thermistors and a heating coil which maintains a 2degC temperature difference between the thermistors. The required electrical power is assumed to be an indicator of cardiac output. The catheter was tested under a variety of loading conditions including changes in heart rate (60, 75, 90, 120 beats/mm), filling pressures (0-15 mmHg), ventricular driving pressures (22-135 mmHg), and pulmonary resistance (0.08-1.47 mmHgcentre not s/mL) in random combinations, generating flows of 1.5-10 L/min. Fluid temperature was varied between 32 and 42degC. Our data demonstrate a good linear relation between the electrical power output of the TruCATH~(TM)/TruCOMMS~(TM) catheter and the actual flow as measured volumetrically. The system appeared to be sensitive to fluid temperature changes, but dimension less analysis with Womersley and Reynolds numbers revealed that it is a direct consequence of the temperature-dependent water viscosity. We conclude that the TruCATH~(TM)/TruCOMMS~(TM) is a potentially useful clinical tool but the absolute correspondence between the catheter output and the patient's actual cardiac output remains to be assessed.