PARAMETER-IDENTIFICATION IN CORONARY PRESSURE-FLOW MODELS - A GRAPHICAL APPROACH

The confident identification of parameters is important in the practic al application of physiological models. However, the task of parameter identification is often complicated by interactions among parameters and by the fact that the sensitivity of the model to changes in a give n parameter is generally a function of all the other parameters. Here we illustrate a graphical approach to parameter identification that al lows the modeler to visualize the behavior of the model, the sensitivi ty functions, and certain functions characteristic of parameter interd ependence. The visual display can be generated over any desired portio n of parameter space. The technique is applied to a simple, four-param eter, myocardial pump model of the coronary circulation. The results i ndicate that over specified ranges of parameters, it is possible to di stinguish among the four parameters of the model: the ratio of proxima l-to-distal resistance, alpha the overall resistance of the vascular b ed, R; the compliance of the vascular bed, C; and a parameter, kappa, relating tissue pressure to left ventricular pressure. It was found th at in order to identify all parameters uniquely, it was necessary to r egress upon both coronary inflow and outflow.