Low-frequency skin microvascular oscillations: dynamics, synchronization and compliance with changes in vascular tone during the tilt test

The purpose is to study the dynamics of low-frequency oscillations (LF; basic frequency of about 0.1 Hz) in the spectra of fingerprint photoplethysmograms (PPG), their synchronization with a similar LF-rhythm in cardiointervalogram (CIG) and compliance with changes in vascular tone during the tilt test in healthy volunteers. Material and Methods. Synchronous cardiointerval recording, breathing recording, left shoulder rheovasography and PPG records from the palm surfaces of distal phalanges of anonymous fingers were analyzed, as well as central hemodynamics data by impedance rheocardiography in 30 healthy volunteers during the tilt test. Dynamics of LF-oscillations in PPG signals, their interaction (including synchronization) with similar oscillations in CIG and vascular tone parameters were studied. Results. At the stages of tilt test the values of LF-oscillations power in the spectra of PPG had no statistically significant differences. During the tilt test the index of synchronization of LF-oscillations increased (p