The model of vascular bed for estimation of human systemic hydrohemodynamics

Abstract

Existing methods of impedance cardiography for estimating blood flow parameters are based on measuring amplitude and temporal characteristics of pulse waves in specific points. Our aim was to improve the algorithm of blood flow analysis using continuous representation of cardiocycle. The suggested algorithm of the vascular blood flow estimation during systolic and diastolic phase of pulse wave is proposed which uses the continuous "integral amplitude" of rheogram. Also, we have developed the basic hemodynamics equation for our heterogeneous model taking into account anthropometric, morphologic and anisotropic properties of various body segments. The resulting formulas were adapted for the estimation of peripheral blood flow in major body segments (head, arms, legs and torso, including abdominal and thoracic regions). A method of controlled systemic hemodynamics estimation is represented which utilizes an automatic commutation scheme with application of 5 electrode pairs on head and extremities. We describe the results of registration of blood flow redistribution between body segmentsduring active orthostatic test with simultaneous control of a checksum, i.e. a difference between the volumes of central and peripheral blood flows. © Springer-Verlag 2007.