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Yu S, Hsu CY, Chuang HY, Yang CC, Lai CL, Yu HS. Abnormalities in Cutaneous Microcirculation in Patients with Alzheimer's Disease, Mild Cognitive Impairment, and Chronic Insomnia Disorder. J Clin Med 2021; 10:jcm10245718. [PMID: 34945014 PMCID: PMC8703751 DOI: 10.3390/jcm10245718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/28/2021] [Accepted: 12/02/2021] [Indexed: 11/23/2022] Open
Abstract
Impaired sympathetic response is frequently observed in neurodegenerative diseases, such as Alzheimer’s disease (AD). On the other hand, chronic insomnia disorder (CID) is also often accompanied by activation of sympathetic nerves. Considering that cutaneous microcirculation reflects sympathetic tone, we hypothesized that baseline cutaneous microcirculation in fingers, as detected by laser Doppler flowmetry (LDF), differs among patients with mild cognitive impairment (MCI), AD, and CID. As light therapy is one of the adjunctive treatments for AD and CID, we designed a randomized controlled cross-over trial of light therapy through eyes for 12 weeks with red light as treatment and green light as control limb, and examined if light therapy has an impact on cutaneous microcirculation. Before light therapy, patients with AD had significantly lower baseline cutaneous perfusion than those with CID in left and right first to fourth fingers. After red light therapy, however, cutaneous perfusion of fingers in CID patients significantly decreased (right fingers, before vs. after = 227.25 ± 62.00 vs. 162.00 ± 49.34, p = 0.007; left fingers, before vs. after = 228.99 ± 58.80 vs. 177.41 ± 59.41, p = 0.003) while cutaneous perfusion of fingers in CID patients did not significantly change after green light therapy. Light therapy with red light also significantly increased cutaneous finger perfusion in patients with AD (right fingers, before vs. after = 130.13 ± 49.82 vs. 172.38 ± 38.32, p = 0.043). Our results suggest that cutaneous perfusion is a useful tool to detect sympathetic dysfunction in patients with CID and AD, and that light therapy with red light is a potential therapeutic intervention to reverse impaired sympathetic function in patients with CID and patients with AD.
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Affiliation(s)
- Sebastian Yu
- Department of Dermatology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807378, Taiwan;
- Department of Dermatology, Kaohsiung Medical University Hospital, Kaohsiung 807377, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
- Neuroscience Research Center, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
| | - Chung-Yao Hsu
- Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807378, Taiwan;
| | - Hung-Yi Chuang
- Department of Public Health and Environmental and Occupational Medicine, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807378, Taiwan;
| | - Chen-Cheng Yang
- Department of Occupational Medicine, Kaohsiung Municipal Siaogang Hospital, Kaohsiung Medical University, Kaohsiung 807378, Taiwan;
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
| | - Chiou-Lian Lai
- Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung 807378, Taiwan;
- Correspondence: (C.-L.L.); (H.-S.Y.)
| | - Hsin-Su Yu
- Graduate Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 807378, Taiwan
- Correspondence: (C.-L.L.); (H.-S.Y.)
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Finžgar M, Frangež HB, Cankar K, Frangež I. Transcutaneous application of the gaseous CO 2 for improvement of the microvascular function in patients with diabetic foot ulcers. Microvasc Res 2020; 133:104100. [PMID: 33181169 DOI: 10.1016/j.mvr.2020.104100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 11/03/2020] [Accepted: 11/03/2020] [Indexed: 01/13/2023]
Abstract
INTRODUCTION Microvascular function is impaired in patients with diabetes mellitus (DM) and is involved in numerous DM complications. Several microvascular-supporting interventions have been proposed of which the transcutaneous application of gaseous CO2 (hereinafter CO2 therapy) is one of the most promising. The aim of present study was to determine the effect of repeated CO2 therapies on the cutaneous microvascular function in DM patients with diabetic foot ulcers. METHODOLOGY A total of 42 subjects with at least one chronic diabetic foot ulcer were enrolled in the study. They were divided into the experimental group (21 subjects aged 64.6 ± 11.6 years) that underwent 4-week-long treatment with transcutaneous application of gaseous CO2 (hereinafter CO2 therapies), and the placebo group (21 subjects aged 65.0 ± 10.7 years) that underwent 4-week-long placebo treatment with transcutaneous application of air. Before the first and after the last treatment in both groups, laser Doppler (LD) flux in foot cutaneous microcirculation, heart rate, and arterial blood pressure measurements were carried out during rest and local thermal hyperaemia (LTH) provocation test. RESULTS In the experimental group the following statistically significant changes were observed after the completed treatment 1) increased mean relative powers of LD flux signals during rest in the frequency bands related to NO-independent endothelial (0.07 ± 0.055 vs. 0.048 ± 0.059, p = 0.0058), NO-mediated endothelial (0.154 ± 0.101 vs. 0.113 ± 0.108, p = 0.015), and neurogenic (0.17 ± 0.107 vs. 0.136 ± 0.098, p = 0.018) activity; 2) decreased resting LD flux (35 ± 29 PU vs. 52 ± 56 PU; p = 0.038); and 3) increased peak LD flux as a function of baseline during LTH (482 ± 474%BL vs. 287 ± 262%BL, p = 0.036); there were no statistically significant changes observed in the placebo group. No systemic effects were observed in none of the two groups by means of mean values of heart rate and arterial blood pressure. CONCLUSIONS Repeated CO2 therapies improves the microvasular function in DM patients without any systemic side effects.
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Affiliation(s)
- Miha Finžgar
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva c. 6, Ljubljana, Slovenia
| | - Helena Ban Frangež
- Department of Obstetrics and Gynaecology, University Medical Centre Ljubljana, Šlajmerjeva ul. 3, 1000 Ljubljana, Slovenia; Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia
| | - Ksenija Cankar
- Institute of Physiology, Faculty of Medicine, University of Ljubljana, Zaloška c. 4, 1000 Ljubljana, Slovenia
| | - Igor Frangež
- Faculty of Medicine, University of Ljubljana, Vrazov trg 2, 1000 Ljubljana, Slovenia; Department of Surgical Infections, University Medical Centre Ljubljana, Zaloška c. 2, 1000 Ljubljana, Slovenia.
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Martini R, Bagno A. The wavelet analysis for the assessment of microvascular function with the laser Doppler fluxmetry over the last 20 years. Looking for hidden informations. Clin Hemorheol Microcirc 2018; 70:213-229. [DOI: 10.3233/ch-189903] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Romeo Martini
- Department of Cardio-Thorax and Vascular Sciences, Unit of Angiology, Azienda Ospedaliera Universitaria di Padova, Italy
| | - Andrea Bagno
- Department of Industrial Engineering, Università di Padova, Italy
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La Fountaine MF, Cirnigliaro CM, Azarelo F, Hobson JC, Tascione O, Swonger KN, Dyson-Hudson T, Bauman WA. Cutaneous microvascular perfusion responses to insulin iontophoresis are differentially affected by insulin resistance after spinal cord injury. Exp Physiol 2017; 102:1234-1244. [PMID: 28671307 DOI: 10.1113/ep086239] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 06/29/2017] [Indexed: 01/06/2023]
Abstract
NEW FINDINGS What is the central question of this study? What impact does insulin resistance have on cutaneous perfusion responses to insulin iontophoresis in vascular beds with markedly reduced or functionally ablated sympathetic nervous system vasomotor function resulting from spinal cord injury? What is the main finding and its importance? Persons with spinal cord injury have sublesional microvascular endothelial dysfunction, as indicated by a blunted cutaneous perfusion response to acetylcholine iontophoresis, and the presence of insulin resistance has a further confounding effect on endothelium-mediated changes to cutaneous perfusion in the lower extremities. Endothelium-mediated mechanisms that regulate skin blood flow might play an integral role in optimizing skin perfusion in vascular beds with sympathetic nervous system vasomotor impairment, such as in spinal cord injury (SCI). Insulin is a vasoactive hormone and second messenger of nitric oxide that facilitates endothelium-mediated dilatation. The effects of insulin resistance (IR) on sublesional cutaneous perfusion responses to insulin provocation have yet to be described in persons with SCI. Persons with SCI and an able-bodied (AB) cohort were divided into subgroups based upon fasting plasma insulin concentration cut-offs for IR (≥13.13 mIU ml-1 ) or insulin sensitivity (IS; <13.13 mIU ml-1 ), as follows: AB, IS (ABIS, n = 21); SCI, IS (SCIS, n = 21); AB, IR (ABIR, n = 9); and SCI, IR (SCIR, n = 11). Laser Doppler flowmetry characterized peak blood perfusion unit (BPU) responses (percentage change from baseline) to insulin, acetylcholine or placebo iontophoresis in the lower extremities; BPU responses were log10 transformed to facilitate comparisons, and the net insulin response (NetIns) BPU response was calculated (insulin minus placebo BPU response). The NetIns was significantly greater in both IS groups compared with their corresponding IR group. The acetylcholine-mediated BPU responses in the SCI subgroups were significantly lower than those in the ABIS group. The proportional BPU responses of NetIns to acetylcholine in the IS cohorts (i.e. ABIS and SCIS) were significantly greater (P < 0.05) than that of each IR subgroup. The presence of IR has a confounding effect on sublesional microvascular endothelium-mediated cutaneous perfusion responses to provocation. Preservation of endothelial sensitivity to its agonists appears to be an important modifiable risk factor to optimize cutaneous perfusion in the lower extremities of persons with SCI.
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Affiliation(s)
- Michael F La Fountaine
- Department of Veterans Affairs Rehabilitation Research & Development Service National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Affairs Medical Center, Bronx, NY, USA.,School of Health and Medical Sciences, Seton Hall University, South Orange, NJ, USA.,The Institute for Advanced Study of Rehabilitation and Sports Science, School of Health and Medical Sciences, Seton Hall University, South Orange, NJ, USA
| | - Christopher M Cirnigliaro
- Department of Veterans Affairs Rehabilitation Research & Development Service National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Affairs Medical Center, Bronx, NY, USA
| | - Frank Azarelo
- Department of Veterans Affairs Rehabilitation Research & Development Service National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Affairs Medical Center, Bronx, NY, USA
| | - Joshua C Hobson
- Department of Veterans Affairs Rehabilitation Research & Development Service National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Affairs Medical Center, Bronx, NY, USA
| | - Oriana Tascione
- State University of New York Downstate College of Medicine, Brooklyn, NY, USA
| | - Kirsten N Swonger
- Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA, USA
| | - Trevor Dyson-Hudson
- Kessler Foundation, West Orange, NJ, USA.,Department of Physical Medicine and Rehabilitation, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - William A Bauman
- Department of Veterans Affairs Rehabilitation Research & Development Service National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters Veterans Affairs Medical Center, Bronx, NY, USA.,Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Rehabilitation Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Sorelli M, Stoyneva Z, Mizeva I, Bocchi L. Spatial heterogeneity in the time and frequency properties of skin perfusion. Physiol Meas 2017; 38:860-876. [DOI: 10.1088/1361-6579/aa5909] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Popa SO, Ferrari M, Andreozzi GM, Martini R, Bagno A. Wavelet analysis of skin perfusion to assess the effects of FREMS therapy before and after occlusive reactive hyperemia. Med Eng Phys 2015; 37:1111-5. [PMID: 26391066 DOI: 10.1016/j.medengphy.2015.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 06/03/2015] [Accepted: 08/19/2015] [Indexed: 11/30/2022]
Abstract
Laser Doppler Fluxmetry is used to evaluate the hemodynamics of skin microcirculation. Laser Doppler signals contain oscillations due to fluctuations of microvascular perfusion. By performing spectral analysis, six frequency intervals from 0.005 to 2 Hz have been identified and assigned to distinct cardiovascular structures: heart, respiration, vascular myocites, sympathetic terminations and endothelial cells (dependent and independent on nitric oxide). Transcutaneous electrical pulses are currently applied to treat several diseases, i.e. neuropathies and chronic painful leg ulcers. Recently, FREMS (Frequency Rhythmic Electrical Modulation System) has been applied to vasculopathic patients, too. In this study Laser Doppler signals of skin microcirculation were measured in five patients with intermittent claudication, before and after the FREMS therapy. Changes in vascular activities were assessed by wavelet transform analysis. Preliminary results demonstrate that FREMS induces alterations in vascular activities.
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Affiliation(s)
- Stefan Octavian Popa
- Department of Industrial Engineering, University of Padova, via Marzolo 9, 35131 Padova, Italy
| | - Myriam Ferrari
- Department of Industrial Engineering, University of Padova, via Marzolo 9, 35131 Padova, Italy
| | - Giuseppe Maria Andreozzi
- UOC of Angiology, "Azienda Ospedale" University of Padova, via Giustiniani 2, 35128 Padova, Italy
| | - Romeo Martini
- UOC of Angiology, "Azienda Ospedale" University of Padova, via Giustiniani 2, 35128 Padova, Italy
| | - Andrea Bagno
- Department of Industrial Engineering, University of Padova, via Marzolo 9, 35131 Padova, Italy.
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Wecht JM, La Fountaine MF, Handrakis JP, West CR, Phillips A, Ditor DS, Sharif H, Bauman WA, Krassioukov AV. Autonomic Nervous System Dysfunction Following Spinal Cord Injury: Cardiovascular, Cerebrovascular, and Thermoregulatory Effects. CURRENT PHYSICAL MEDICINE AND REHABILITATION REPORTS 2015. [DOI: 10.1007/s40141-015-0093-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Processing of laser Doppler flowmetry signals from healthy subjects and patients with varicose veins: Information categorisation approach based on intrinsic mode functions and entropy computation. Med Eng Phys 2015; 37:553-9. [DOI: 10.1016/j.medengphy.2015.03.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 02/14/2015] [Accepted: 03/27/2015] [Indexed: 11/18/2022]
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Humeau-Heurtier A, Abraham P, Mahe G. Analysis of laser speckle contrast images variability using a novel empirical mode decomposition: comparison of results with laser Doppler flowmetry signals variability. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:618-627. [PMID: 25347875 DOI: 10.1109/tmi.2014.2364079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Laser Doppler flowmetry (LDF) and laser speckle contrast imaging (LSCI) have emerged as noninvasive optical modalities to monitor microvascular blood flow. Many studies proposed to extract physiological information from LDF by analyzing signals variability. By opposition, such analyses for LSCI data have not been conducted yet. We propose to analyze LSCI variability using a novel data-driven method: the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN). CEEMDAN is suitable for nonlinear and nonstationary data and leads to intrinsic mode functions (IMFs). It is based on the ensemble empirical mode decomposition (EEMD) which relies on empirical mode decomposition (EMD). In our work the average frequencies of LSCI IMFs given by CEEMDAN are compared with the ones given by EMD and EEMD. Moreover, LDF signals acquired simultaneously to LSCI data are also processed with CEEMDAN, EMD and EEMD. We show that the average frequencies of IMFs given by CEEMDAN depend on the signal-to-noise ratio (SNR) used in the computation but, for a given SNR, the average frequencies found for LSCI are close to the ones obtained for LDF. By opposition, EEMD leads to IMFs with frequencies that do not vary much when the SNR level is higher than a threshold. The new CEEMDAN algorithm has the advantage of achieving a complete decomposition with no error in the reconstruction but our study suggests that further work is needed to gain knowledge in the adjustment of the added noise level. CEEMDAN, EMD and EEMD are data-driven methods that can provide a better knowledge of LSCI.
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Humeau-Heurtier A, Mahé G, Abraham P. Microvascular blood flow monitoring with laser speckle contrast imaging using the generalized differences algorithm. Microvasc Res 2015; 98:54-61. [PMID: 25576743 DOI: 10.1016/j.mvr.2014.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/22/2014] [Accepted: 12/27/2014] [Indexed: 10/24/2022]
Abstract
Laser speckle contrast imaging (LSCI) is a full-field optical technique to monitor microvascular blood flow with high spatial and temporal resolutions. It is used in many medical fields such as dermatology, vascular medicine, or neurosciences. However, LSCI leads to a large amount of data: image sampling frequency is often of several Hz and recordings usually last several minutes. Therefore, clinicians often perform regions of interest in which a spatial averaging of blood flow is performed and the result is followed with time. Unfortunately, this leads to a poor spatial resolution for the analyzed data. At the same time, a higher spatial resolution for the perfusion maps is wanted. To get over this dilemma we propose a new post-acquisition visual representation for LSCI perfusion data using the so-called generalized differences (GD) algorithm. From a stack of perfusion images, the procedure leads to a new single image with the same spatial resolution as the original images and this new image reflects perfusion changes. The algorithm is herein applied on simulated stacks of images and on experimental LSCI perfusion data acquired in three different situations with a commercialized laser speckle contrast imager. The results show that the GD algorithm provides a new way of visualizing LSCI perfusion data.
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Affiliation(s)
- Anne Humeau-Heurtier
- University of Angers, LARIS - Laboratoire Angevin de Recherche en Ingénierie des Systèmes, 62 Avenue Notre-Dame du Lac, 49000 Angers, France.
| | - Guillaume Mahé
- University of Rennes 1, CHU of Rennes, Pôle Imagerie Médicale et Explorations Fonctionnelles, 35033 Rennes Cedex 9, France; INSERM, CIC 1414 "Ischemia, Macro and Microcirculation" Group, 35033 Rennes Cedex 9, France
| | - Pierre Abraham
- University of Angers, CHU of Angers, Laboratoire de Physiologie et d'Explorations Vasculaires, UMR CNRS 6214-INSERM 1083, 49033 Angers Cedex 01, France
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Liao F, Jan YK. Enhanced phase synchronization of blood flow oscillations between heated and adjacent non-heated sacral skin. Med Biol Eng Comput 2012; 50:1059-70. [PMID: 22936012 DOI: 10.1007/s11517-012-0948-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 08/08/2012] [Indexed: 01/08/2023]
Abstract
The study of skin microcirculation may be used to assess risk for pressure ulcers. It is observed that local heating causes an increase in blood flow of not only 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, 0.02-0.05, 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 exhibited 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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Affiliation(s)
- Fuyuan Liao
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
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Humeau-Heurtier A, Mahé G, Chapeau-Blondeau F, Rousseau D, Abraham P. Study of time reversibility/irreversibility of cardiovascular data: theoretical results and application to laser Doppler flowmetry and heart rate variability signals. Phys Med Biol 2012; 57:4335-51. [PMID: 22705853 DOI: 10.1088/0031-9155/57/13/4335] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Time irreversibility can be qualitatively defined as the degree of a signal for temporal asymmetry. Recently, a time irreversibility characterization method based on entropies of positive and negative increments has been proposed for experimental signals and applied to heart rate variability (HRV) data (central cardiovascular system (CVS)). The results led to interesting information as a time asymmetry index was found different for young subjects and elderly people or heart disease patients. Nevertheless, similar analyses have not yet been conducted on laser Doppler flowmetry (LDF) signals (peripheral CVS). We first propose to further investigate the above-mentioned characterization method. Then, LDF signals, LDF signals reduced to samples acquired during ECG R peaks (LDF_R(ECG) signals) and HRV recorded simultaneously in healthy subjects are processed. Entropies of positive and negative increments for LDF signals show a nonmonotonic pattern: oscillations--more or less pronounced, depending on subjects--are found with a period matching the one of cardiac activity. However, such oscillations are not found with LDF_R(ECG) nor with HRV. Moreover, the asymmetry index for LDF is markedly different from the ones of LDF_R(ECG) and HRV. The cardiac activity may therefore play a dominant role in the time irreversibility properties of LDF signals.
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Affiliation(s)
- Anne Humeau-Heurtier
- LUNAM Université, LISA-Laboratoire d'Ingénierie des Systèmes Automatisés, 62 avenue Notre Dame du Lac, 49000 Angers, France
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