Bio-Impedance Signal Decomposer (BISD) as an Adaptive Signal Model Based Separator of Cardiac and Respiratory Components

Abstract

The paper presents the Bio-Impedance Signal Decomposer (BISD) for adaptive separation of two infra-low frequency signals: cardiac and respiratory bio-impedance (BI) signals, which are the time varying components of the total electrical BI signal. The adaptively tuneable cardiac BI signal model (CBISM), constructed from components of a specially designed orthonormal basis is the key element of the proposed BISD. If combined with the signal-shape locked loop (SSLL) concept, this allows an on-line decomposition of a BI signal into its cardiac and respiratory components with partially overlapping spectra. The proposed BISD is currently designed and realised as a digital (PC software) system. The solution is also oriented to be used for portable and implantable cardiac devices, such as rate adaptive pacemakers as well as for stationary devices in clinical conditions.