Changes in non-invasive wave intensity parameters with variations of Savitzky-Golay filter settings

Ultrasound-measured waveforms, such as vessel diameter and blood flow velocity, are used to perform analysis of waves in the cardiovascular system. Wave intensity analysis is one of the tools used for this purpose. The waveforms are commonly filtered to eliminate high-frequency noise, however the filter settings affect the features of these signals and especially of their time derivatives, upon which wave intensity analysis is based. This study aims to investigate the alterations of wave intensity parameters with varying Savitzky-Golay filter settings, one of the most common smoothing algorithms used in this context. A broad spectrum of variations was observed in all the wave intensity variables. It is therefore important to always specify the filter settings applied to the signals in a wave intensity study, so that appropriate comparisons can be made.