A Mathematical Representation of the Thermodilution Curve

Abstract

The primary purpose of this study was to develop a mathematical representation of the thermodilution cardiac output curve. Further work focused on the development of an empirical model and a software implementation to measure cardiac output with improved patient diagnostic efficiency (speed) by area prediction. The empirical model is equivalent to a second-order over-damped system with a rectangular pulse as input. The output of the system represents the thermal response. The curve is constrained in that it follows the area criterion assumed by many cardiac output units. A software implementation of this model used to predict cardiac output takes in measured values of a thermal response up to the curve’s peak and matches time constants with the model to derive a predicted curve. In matching the curve, the software also produces data that assesses the error between the two curves (measured and predicted).