Reduced-order nonlinear arterial compliance parameter estimation under vasoactive states

The arterial system is coupled with the heart, such that the pressure produced by the left ventricle of the heart is in tune to properties of the vasculature. A modified 3-element Windkessel model of the arterial system can closely approximate the complex load presented to the heart, but difficulties in estimating nonlinear arterial parameters have led compliance to be frequently modeled as a constant-valued element. Previously, a method that estimated the parameters from pressure- and flow-derived pressure-volume curves showed good estimates for high pressure and stiff arterial systems, but yielded poor results for lower pressure and compliant systems. We propose here a reduced-order approach in estimating nonlinear compliance parameters that yields good results for various vasocactive states corresponding to low-, normal, and high-pressure arterial systems in good agreement with previous experimental findings.