Improvements of scale fourier linear combiner for impedance cardiography analysis.

In this paper, we present two additions to the SFLC algorithm in order to improve the beat by beat estimation of fiducial points (B and X) and the maximum value of the derivative in impedance cardiography signal: addition of a reference input and scanning each beat more than once. On data synthesized from real ICG which exhibits beat by beat changes and baseline variations, we used statistical measures to show that the modified algorithms give accurate beat by beat estimation conversely to the original version of SFLC. We also give results on a real ICG using phono cardiography as a reference. In this case too, results show the pertinence of the proposed improvements.

Impedance cardiography filtering using scale Fourier linear combiner based on RLS algorithm.

The Cardiac Output (CO) can be calculated from the thoracic cardio-impedance signal from several methods, and all of them are linked to the frequency information, information that is limited by the type of filtering used before. A methodology is proposed to evaluate the effect of the commonly used methods of filtering, and an improvement of the SFLC LMS-based algorithm by the use of RLS algorithm is also tested. Performances of algorithms are then evaluated considering different types of noise such as white noise or combination of sinusoidal noises to simulate the effect of respiration and body movements.