Effect of Spinal Cord Injury on Nonlinear Complexity of Skin Blood Flow Oscillations

This study investigated the effect of spinal cord injury (SCI) on nonlinear complexity of skin blood flow oscillations (BFO). Complexity of the characteristic frequencies embedded in BFO was described by the scaling coefficient derived by detrended fluctuation analysis (DFA) and the range of scaling coefficients derived from multifractal detrended fluctuation analysis (MDFA) in specific scale intervals. 23 subjects were recruited into this study, including 11 people with SCI and 12 healthy controls. Local heating-induced maximal sacral skin blood flow was measured by laser Doppler flowmetry. The results showed that metabolic BFO (0.0095-0.02 Hz) exhibited significantly lower complexity in people with SCI as compared with healthy controls (p<0.01) during maximal vasodilation. This study demonstrated that complexity analysis of BFO can provide information of blood flow dynamics beyond traditional spectral analysis.