Time frequency analysis of the experimental electrical impedance of pulsatile blood flowing through rigid tubes

Abstract

An Impedance Cardiogram (ICG) contains small fluctuations that are not explained by blood volume changes alone. The orientation of flowing red blood cells directly influences the measured impedance, and this may be one source of such fluctuations. In this paper the impedance and velocity of pulsatile blood flowing through rigid tubes has been experimentally collected and analyzed in the time and frequency domains. The time frequency distributions are presented for both velocity and impedance of pulsatile blood. In particular, the frequency content of velocity and impedance are well correlated during the acceleration and deceleration phases of flow, and less correlated during changes in the direction of acceleration. This is believed to be due to the influence of changes in red blood cell orientation at these times and may lead to further understanding of the origin of fluctuations in an ICG. © 2009 Springer-Verlag.