Low-frequency fluctuations in the laser Doppler flow signal (LDFS) from the skin are related to microvascular
mechanisms of flow control. Wavelet spectral analysis has been used to correlate fluctuations in the LDFS with the
endothelial, neurogenic and myogenic mechanisms of control in the frequency intervals 0.005-0.02 Hz, 0.02-0.06 Hz and
0.06-0.16 Hz, respectively. Generally the signal power, in each frequency interval, derived from the respective wavelet
coefficients, is used as a measure of the activity of the related mechanism of microvascular control. However, the time-domain
characteristics of the fluctuations in the LDFS in each frequency interval are poorly known. As a consequence,
there is a lack of objective criteria to properly measure, in each frequency interval, the related hemodynamic parameters.
Here a time-domain method is proposed to analyze and quantify fluctuations in the LDFS in each frequency band.
Baseline (32 degrees Celsius) and thermally stimulated (42 degrees Celsius) LDFS of forearms from 15 healthy
volunteers were collected and analyzed. The data obtained indicate that inappropriate time windows, frequently used for
measurements, increase the variability of the measured signal power, diminishing the capability of the method when
assessing microvascular dynamics and dysfunctions. To overcome this limitation, an objective method to measure the
LDFS power in each frequency band is proposed.