Applicability of an effective conductivity approach in modeling thoracic impedance changes

This paper describes numerical simulations of the influence of conductivity changes inside a volume conductor on impedance changes measured on its surface. A simple model based on the finite element method has been developed to estimate an applicability of the effective conductivity theory in human chest modeling. The model consisted of a cylinder with two concentric spheres inside. Simulations were performed for two cases: first the geometry was changing and material properties were constant within each subdomain, next, the geometry was constant but conductivity values were changing for each phase of cardiac cycle. In the considered range of geometry changes dependence between impedance changes calculated for two models was linear. Performed simulations showed that effective conductivity approach can be utilized when studying dynamic processes involved by volume changes of internal organs.