Artifact Removal from the Radial Bioimpedance Signal using Adaptive Wavelet Packet Transform

Impedance cardiography has become a synonym for indirect assessment of monitoring the stroke volume, cardiac output and other hemodynamic parameters by monitoring the blood volume changes of the body in terms of changes in the electrical impedance of a body segment. Changes occurring in the impedance of the body due to various physiological processes are captured in terms of the voltage variation. But this method is affected by electrical noise such as power line hum and motion and respiratory artifacts due to movement of the subject while acquiring the bioimpedance signal. This can cause errors in the automatic extraction of the characteristic points for estimation the hemodynamic parameters. This paper presents an adaptive algorithm for baseline wander removal from the bioimpedance waveform, obtained at the radial pulse of the left hand, using the wavelet packet transform. The algorithm computes the energy in scale of the wavelet coefficients. The energies in the successive scales are compared and the branch of wavelet binary tree with the higher energy is selected. The impedance signals have been acquired by using the peripheral pulse analyzer and excellent results are obtained.

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