Human skin microcirculation after brachial plexus block evaluated by wavelet transform of the laser Doppler flowmetry signal.

Background: The skin microcirculation may be evaluated noninvasively by laser Doppler flowmetry and iontophoresis with acetylcholine and sodium nitroprusside. Wavelet transform of the perfusion signal shows periodic oscillations of five characteristic frequencies in the interval 0.0095-1.