Power spectral analysis of perfusion signals on free radial forearm flap transplantation in humans

Forearm cutaneous perfusion is an established in vivo model in many clinical and basic researches to explore the peripheral circulation. The aim of our study is to characterize the dynamic properties of regional microcirculation after simultaneous denervation and revascularization in free forearm flap transplantations. Serial changes in laser Doppler flow and cutaneous temperature were measured during 14 forearm flap transplantations. Digitalized perfusion data were relayed for power spectral analysis based on the fast Fourier transform. Real time heart rate variability was measured to verify the influence of systemic autonomic nervous modulations. The basal flow expressed a threefold to fourfold increase, from 20.31 ± 3.25 to 73.79 ± 11.78 PU, after the transplantation. Frequency domain analysis of cutaneous blood flow variability showed significantly increased high frequency (0.15-0.4 Hz, 55.14% ± 3.31% to 65.31% ± 2.78%, P = 0.0035) and decreased very low frequency (0.003-0.04 Hz, 18.61% ± 2.70% to 9.25% ± 1.38%, P = 0.0049) power fraction after flap transfer. Simultaneous denervation and revascularization of forearm flaps increased the regional blood flow significantly that was caused by increased high frequency and decreased very low frequency fractional contributions in dynamic regulation of regional cutaneous microcirculation. They are associated with the sympathetic denervation and reactive hyperemia, respectively.