Using multifractal detrended fluctuation analysis to assess sacral skin blood flow oscillations in people with spinal cord injury

Liao, Fuyuan; Jan, Yih‐Kuen

doi:10.1682/jrrd.2010.08.0145

Cited by 25 publications

(19 citation statements)

References 44 publications

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“…spinal cord injury, peripheral neuropathy) on microvascular dysfunction and its influences on the risk for ischemic injury and subsequent pressure ulcers. We also demonstrated that nonlinear properties of skin BFO are associated with vasodilatory function [20, 21]. By assessing the nonlinear property of blood flow oscillations, the clinicians may better understand the effect of various risk factors of pressure ulcer on causing soft tissue ischemia.…”

Section: Discussionmentioning

confidence: 99%

“…The study of skin microcirculation may be used to assess risk for pressure ulcers and effectiveness of preventive intervention [11, 12, 14, 15, 21]. A basic function of skin microcirculation is to regulate blood flow to meet the metabolic demands of local cells and to regulate skin temperature through a dynamic control of vascular resistance and blood flow redistribution [34, 35].…”

Section: Introductionmentioning

confidence: 99%

“…In addition to frequency components of BFO, the complexity of BFO also provides useful information to quantify microvascular dysfunction. Liao and Jan demonstrated that a decrease in complexity of skin BFO is associated with impaired vasodilation in people with SCI [21]. The exact role of skin blood flow in the pressure ulcer development remains to be determined.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced phase synchronization of blood flow oscillations between heated and adjacent non-heated sacral skin

Liao

Jan

2012

Med Biol Eng Comput

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The study of skin microcirculation may be used to assess risk for pressure ulcers. It is observed that local heating not only causes an increase in blood flow of the heated skin but also in the adjacent non-heated skin. The underlying physiological mechanism of this indirect vasodilation of the non-heated skin remains unclear. We hypothesized that blood flow oscillations (BFO) in the adjacent non-heated skin area synchronize with BFO in the heated skin, thus inducing a vasodilatory response. We investigated BFO in the heated and adjacent non-heated skin (12.1±1.2 cm distance) on the sacrum in 12 healthy participants. The ensemble empirical mode decomposition (EEMD) was used to decompose blood flow signals into a set of intrinsic mode functions (IMFs), and the IMFs with power spectra over the frequency range of 0.0095–0.02 Hz, 0.02–0.05 Hz, and 0.05–0.15 Hz were chosen as the characteristic components corresponding to metabolic, neurogenic, and myogenic regulations, respectively. Then, the instantaneous phase of the characteristic components was calculated using the Hilbert transform. From the time series of phase difference between a pair of characteristic components, the epochs of phase synchronization were detected. The results showed that myogenic and neurogenic BFO exhibit self-phase synchronization during the slower vasodilation of the heated skin. In the non-heated skin, the degree of synchronization of BFO is associated with the changes in blood flow.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Enhanced phase synchronization of blood flow oscillations between heated and adjacent non-heated sacral skin

Liao

Jan

2012

Med Biol Eng Comput

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“…An application of MF-DFA may cover many dierent problems in science, just to mention examples in seismology [12,13], cosmology [14], biology [15,16], meteorology [17], medicine [18], epidemiology [19], music [20,21], geophysics [22] and mostly nances [2331].…”

Section: Introductionmentioning

confidence: 99%

Multifractality of Nonlinear Transformations with Application in Finances

Grech

Pamuła

2013

Acta Phys. Pol. A

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We study the multifractal eects of nonlinear transformations of monofractal, stationary time series and apply the found results to measure the true unbiased multifractality generated only by multiscaling properties of initial (primary) data before transformations. A dierence is stressed between naive observed multifractal eects calculated directly within detrended multifractal analysis as the spread ∆h of the generalized Hurst exponents h(q) and the more reliable unbiased multifractality received after subtraction of residual bias eects generated by nonlinear transformations of initial data and coupled with nite size eects in time series. This property is investigated for volatile series of the real main world nancial indices. A dierence between multifractal properties of intraday and interday quotes is also pointed out in this context for the Warsaw Stock Exchange WIG index.Finally, based on the observed feature of real nonstationary data, a new measure of unbiased multifractality in signals is introduced. This measure comes from an analysis of the whole generalized Hurst exponent prole instead of looking just at its edge behavior h ± ≡ h(q → ±∞). Such an approach seems to be particularly useful when h(q) is not a monotonic function of the moment order q. Interesting examples with extreme events from nance are presented. They convince that an analysis directed only on investigation of the edges h ± in multifractal spectrum may be misleading.

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“…Skin blood flow has been found to exhibit irregular fluctuations over time [14–16]. Griffith [15] suggested that spontaneous contraction and dilation of the vessel wall and the nonlinear rheological properties of blood may contribute to this phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Assessing complexity of skin blood flow oscillations in response to locally applied heating and pressure in rats: Implications for pressure ulcer risk

Liao

O’Brien

Jan

2013

Physica A: Statistical Mechanics and its Applications

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The objective of this study was to investigate the effects of local heating on complexity of skin blood flow oscillations (BFO) under prolonged surface pressure in rats. Eleven Sprague–Dawley rats were studied: 7 rats underwent surface pressure with local heating (Δt = 10 °C) and 4 rats underwent pressure without heating. A pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin blood flow was measured using laser Doppler flowmetry. The loading period was divided into nonoverlapping 30 min epochs. For each epoch, multifractal detrended fluctuation analysis (MDFA) was utilized to compute DFA coefficients and complexity of endothelia related metabolic, neurogenic, and myogenic frequencies of BFO. The results showed that under surface pressure, local heating led to a significant decrease in DFA coefficients of myogenic frequency during the initial epoch of loading period, a sustained decrease in complexity of myogenic frequency, and a significantly higher degree of complexity of metabolic frequency during the later phase of loading period. Surrogate tests showed that the reduction in complexity of myogenic frequency was associated with a loss of nonlinearity whereas increased complexity of metabolic frequency was associated with enhanced nonlinearity. Our results indicate that increased metabolic activity and decreased myogenic response due to local heating manifest themselves not only in magnitudes of metabolic and myogenic frequencies but also in their structural complexity. This study demonstrates the feasibility of using complexity analysis of BFO to monitor the ischemic status of weight-bearing skin and risk of pressure ulcers.

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Using multifractal detrended fluctuation analysis to assess sacral skin blood flow oscillations in people with spinal cord injury

Cited by 25 publications

References 44 publications

Enhanced phase synchronization of blood flow oscillations between heated and adjacent non-heated sacral skin

Enhanced phase synchronization of blood flow oscillations between heated and adjacent non-heated sacral skin

Multifractality of Nonlinear Transformations with Application in Finances

Assessing complexity of skin blood flow oscillations in response to locally applied heating and pressure in rats: Implications for pressure ulcer risk

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