IDENTIFICATION OF THE 3-ELEMENT WINDKESSEL MODEL INCORPORATING A PRESSURE-DEPENDENT COMPLIANCE

A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel model of the art erial system incorporating a pressure-dependent compliance. The data r equired are pulsatile aortic pressure and flow. The basic assumptions are a steady-state periodic regime and a purely elastic compliant elem ent. By stating two conditions, zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are d etermined through simple closed form formulas as functions of mean val ues of the square of aortic pressure, the square of aortic flow, and t he product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be then obtained s o allowing the calculation of volume variation and compliance as funct ions of pressure. The feasibility of this method is studied by applyin g it to both simulated and experimental data relative to different cir culatory conditions and comparing the results with those obtained by a n iterative parameter optimization algorithm and with the actual value s when available. The conclusion is that the proposed method appears t o be effective in identifying the three-element windkessel even in the case of nonlinear compliance.