A Modified Windkessel Model And Its Parameter Estimation Based On Photoplethysmograph

Cardiovascular system is one of the most complicated systems in the humanbody. Clinical experiment and animal experiment were the main ways of research oncardiovascular system before, but some experiments cannot be done on account oftechnologies and morals. Moreover, there are great differences between the humanand the animal, so the results from the animal experiment are short of reliability.Plenty of time and money are also needed for the experiment in order to draw asimple conclusion. With the development of mathematical and physical model, theseproblems in the experiment are solved.We can analyze and predict the operating mechanism and the changingregulations of some diseases using mathematical or physical model of cardiovascularsystem. In this way, it will replace of complex experiment, and increase the researchefficiency greatly. In this thesis, we propose a three-elastic cavity cardiovascularsystem model on the basis of the windkessel model, and we use the software Matlabto process the model. We regard the cardiovascular system model as a linearmechanical-model, heart beat is the input of the system and the Photoplethysmograph(PPG) is the output of the system. We can estimate the structure and the parameter ofthe system by analyzing the relations between the input and the output, then adjustingthe model's parameters, make the output of the model consistent with the pulse wavecharacteristic in experiment.Subsection function is used to describe the structure of the model based oncharacters of the heart striking. Then a RLC circuit model is established to model thecardiovascular blood system, the resistance R the resistance of vascular, the capacityC represents the elasticity of vascular, and the inductance L represents the complianceof vascular. The model parameters can be estimated with the Runge-Kutta solution inMatlab7.0. In conclusion, the outputs of the model are similar with the PPG. The model hassolved the problems in experiment. The three-elastic cavity model established in thisstudy provides an extendable simulation tool for studying the physiological andpathological characteristics of cardiovascular system.