Transitions in skin blood flow fractal scaling: The importance of fluctuation amplitude in microcirculation


Esen H., ATA N. , ESEN F.

MICROVASCULAR RESEARCH, vol.97, pp.6-12, 2015 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 97
  • Publication Date: 2015
  • Doi Number: 10.1016/j.mvr.2014.07.014
  • Title of Journal : MICROVASCULAR RESEARCH
  • Page Numbers: pp.6-12

Abstract

Detrended fluctuation analysis (DFA) of laser Doppler flowmetry (LDF) time series from volar skin reveals three scaling regions: cardiac, cardio-respiratory and local. Scaling exponents, slopes (alpha(C), alpha(CR) and alpha(L)) of the straight lines, in these regions indicate correlation properties of LDF signal. Transitions from uncorrelated to positive in cardiac (alpha(C)) and positive to negative correlations in the cardio-respiratory (alpha(CR)) exponent have been observed for vasodilatation signals in response to local heating. However, positive correlation in local region (alpha(L)) did not change with vasodilatation. We studied whether the transitions in scaling exponents are correlated with the increase in peak to peak fluctuation amplitude (A(F)) of LDF signal. LDF signals were normalized to unity using average values of their pulsatile parts: baseline and saturation signals. If A(F) of normalized LDF signal is >= 0.5, we observed transitions in alpha(C) and in alpha(CR) but not in alpha(L), in healthy subjects. It is suggested that the transition from positive to negative correlation in alpha(CR) with increasing amplitude may be explained by intact arteriolar myogenic activity in healthy young (Y) and middle aged (MA) subjects. In contrast, we did not observe transition in alpha(CR) suggesting impaired myogenic activity in patients with essential hypertension (EHT). (C) 2014 Elsevier Inc. All rights reserved.