Wavelet phase coherence analysis of the skin blood flow oscillations in human

• The wavelet phase coherence of contralateral skin blood flow oscillations was studied.
• The reliability of the obtained values was estimated using the method of surrogates.
• High reliable coherence was obtained for myogenic, respiratory and cardiac rhythms.
• Central mechanisms of synchronization of cardiovascular oscillations are assumed.

The wavelet phase coherence of oscillations in the peripheral blood flow of contralateral skin sites was studied in 20 healthy subjects. Skin perfusion was registered simultaneously on similar regions of the outer sides of the right and left forearms by the laser Doppler flowmetry technique. To estimate the reliability of the obtained wavelet phase coherence values we applied the comparative method using amplitude-adjusted Fourier transform surrogates. High median values (0.63 and 0.59) of the wavelet phase coherence were obtained for the frequency intervals of respiratory (0.145–0.6 Hz) and cardiac (0.6–2 Hz) rhythms in 18 and 20 participants, respectively. In all the 20 participants we detected high and reliable values (Ме = 0.72) of the wavelet phase coherence for skin blood flow oscillations in the myogenic interval (0.052–0.145 Hz). Additionally, we demonstrated high wavelet phase coherence in the neurogenic (0.021–0.052 Hz) and endothelial (0.0095–0.021 Hz) intervals in 8 and 7 participants, respectively. The corresponding medians of the reliable wavelet phase coherence values for these intervals were 0.74 and 0.82. The obtained results suggest that the microvascular blood flow possesses not only the local mechanisms of generating low-frequency blood flow oscillations, but also a central mechanism, which is likely to synchronize low-frequency oscillations throughout the whole cardiovascular system.