Wavelet Analysis of Laser-Induced Blood Flow Changes

Abstract

Background:

It has been shown that low-level laser irradiation induces vascular relaxation leading to improved microcirculation.

Objective:

To provide additional insight into the mechanisms of laser-induced vascular relaxation.

Design, Setting, and Participants:

Continuous wavelet transformation was applied to laser Doppler spectroscopy signals that were recorded immediately before and after a standardized laser needle stimulation over acupuncture point Neiguan (PC 6) in 6 healthy, nonsmoking men. Five oscillatory components in the frequency interval from 0.0095 to 2 Hz were analyzed corresponding to cardiac, respiratory, neurogenic, myogenic, and endothelial related activity.

Main Outcome Measures:

Measurement of skin blood flow and spectral amplitudes.

Results:

Findings demonstrated that laser needle stimulation had no statistically significant effect on peripheral blood flow and microvascular control under the conditions of the present study. Overall, the group average skin blood flow decreased from 6.46 arbitrary units (AU) before laser needle treatment to 5.18 AU after laser irradiation (99% CI for the mean difference: -0.5 to 3.06 AU).

Conclusions:

Observations pointed toward increased neurogenic and myogenic influences. Therefore, our results suggest that wavelet analysis enables valid differentiation of particular subsystems of microvascular control in response to laser needle treatment. Further research in terms of randomized controlled trials is required.