Study of digital blood pressure and laser Doppler flowmetry signals through a multiscale analysis

Multiscale entropy (MSE) analysis allows quantifying the complexity of time series over multiple time scales. MSE can be useful to identify impaired cardiovascular control. Therefore, to better understand the regulatory mechanisms of the peripheral cardiovascular system, we have processed digital blood pressure (BP) and laser Doppler flowmetry (LDF) signals from finger and forearm with MSE. BP and LDF signals have been recorded simultaneously on 6 healthy subjects before and after a vasodilator administration (glycerin trinitrate, GTN). Our results show that BP and LDF signals do not have a constant complexity over scales. Moreover, a minimum, which may reflect the cardiac activity, was identified on MSE profiles. For BP signals GTN induces changes in the complexity. We also note that, after GTN administration, the complexity of LDF signals from forearm is increased for the largest scales studied herein while no changes are observed for the one of LDF signals from finger.