Physical Model of the Pulmonary Circulation Designed for Investigation on Cardiac Output Measurement by Means of the Thermodilution Method

Abstract

The "gold clinical standard" of cardiac output measurements is the thermodilution method, implemented by the Swan-Ganz catheter. The unreliability of obtained results is difficult to estimate experimentally, due to the lack of reference methods or the risk of serious interferences in the measured object. Moreover, the pulsating blood flow produced by the heart is difficult to measure. Therefore it is advisable to develop the physical model of the pulmonary circulation, designed to investigate the accuracy of cardiac output measurements by means of the thermodilution method.

The Influence of Limited Dynamic Response of the Indicator Detector in a Swan-Ganz Catheter on the Overestimation of Cardiac Output Measurement By Means of Thermodilution

“…5) that dT/dt depends on the flow and area of the cross-section of the vessel with the following relationship: the lower the flow, the greater dT/dt. This effect was confirmed experimentally in measurements of CO by means of thermodilution carried out on the physical model of pulmonary circulation [12,16]. The courses of IDC obtained for three values of flow (0.98, 1.81 and 2.40l/min) are presented in Fig.…”

Analysis of actual accuracy in cardiac output measurements by means of thermodilution

“…The continuous flow (which -in steady-state -equals the pulsating flow) was measured by a rotameter with an accuracy of 1.5%. The functional verification of the developed model was performed by comparing the course of the dilution phenomenon (IDC curves) occurring in the physical model and the human circulatory system (13). It was unequivocally proved that the model is able to simulate faithfully CO measurements by means of thermodilution.…”

“…• for blood substitute: specific heat = 3528 J/kg·K, mass density = 1065 kg/m • no human or animal blood was used, physical experiments were performed on an adequate model of the pulmonary circulation [13].…”

“…To estimate experimentally the unreliability of thermodilution an adequate physical model of the pulmonary circulation was applied (Fig. 5) [13]. It consisted of the following parts: the right atrium, right ventricle, pulmonary artery valve, tricuspid valve, pulmonary trunk and left and right pulmonary arteries.…”