Journal ArticleDOI
Electric properties of flowing blood and impedance cardiography
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TLDR
The resistivity of flowing blood is found to be a function of the shear rate profile, and the resistivity changes in elastic tubes are influenced by both velocity changes and changes in diameter, but in opposite directions.Abstract:
An effective resistivity is defined for axisymmetric flow through a circular tube with a uniform electric field in the longitudinal direction. The resistivity of flowing blood is found to be a function of the shear rate profile. Under axisymmetric conditions shear rate profiles are a function of a single parameter: the reduced average velocity, which is the average velocity divided by the radius of the tube. The resistivity of human blood was investigated while the blood was in laminar flow in a circular tube with different constant flow rates. The relative change in resistivity in % is given by: −0.45·H·{1-exp[−0.26·(〈v〉/R)0.39]}; where H is the packed cell volume in % and 〈v〉/R is the reduced average velocity in s−1. In accelerating flow the resistivity change is synchronous with the change in flow rate, but in decelerating flow there is an exponential decay characterized by a relaxation time τ. For packed cell volumes of 36.4% and 47.5% τ was estimated to be 0.21 s, for a packed cell volume of 53.7% τ was estimated to be 0.29 s. The resistivity changes in elastic tubes are influenced by both velocity changes and changes in diameter, but in opposite directions.read more
Citations
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Patent
Apparatus and methods of bioelectrical impedance analysis of blood flow
TL;DR: In this paper, a multi-parameter algorithm derived using stepwise multiple linear regression or other optimization techniques is presented for computing cardiac output from bio-electrical impedance values using a multiscale algorithm, which can be used to control administration of intravenous fluids or medication to an organism or to optimize a pacemaker.
Journal ArticleDOI
Principles of electrical impedance tomography and its clinical application.
TL;DR: Electrical impedance tomography is a promising functional tomography technology on the verge of its clinical application and potential applications in the future as well as limitations of EIT technology are described.
Journal ArticleDOI
Stroke volume equation for impedance cardiography.
TL;DR: Compared with TDCO, equation N, using a square-root transformation for dZ/dtmax/Z0, and a mass-based VC was superior to existing transthoracic impedance techniques for SV and CO determination.
Journal ArticleDOI
Measuring impedance in congestive heart failure: current options and clinical applications.
W.H. Wilson Tang,Wilson Tong +1 more
TL;DR: A critical review of the current understanding and promises of impedance measurements, the techniques that have evolved, as well as the evidence and limitations regarding their clinical applications in the setting of heart failure management is provided.
Journal ArticleDOI
Multiple sources of the impedance cardiogram based on 3-D finite difference human thorax models
Li Wang,Robert P Patterson +1 more
TL;DR: The results suggest that the thoracic impedance cardiographic signal is a mixed representation of many inseparable factors and may not be reliable for the stroke volume calculation.
References
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Book
Boundary layer theory
TL;DR: The flow laws of the actual flows at high Reynolds numbers differ considerably from those of the laminar flows treated in the preceding part, denoted as turbulence as discussed by the authors, and the actual flow is very different from that of the Poiseuille flow.
Book
Electrodynamics of continuous media
TL;DR: In this article, the propagation of electromagnetic waves and X-ray diffraction of X rays in crystals are discussed. But they do not consider the effects of superconductivity on superconducting conductors.
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Multiple sources of the impedance cardiogram based on 3-D finite difference human thorax models
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