151
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Hsiu H, Hsu WC, Wu YF, Hsu CL, Chen CY. Differences in the Skin-Surface Laser Doppler Signals Between Polycystic Ovary Syndrome and Normal Subjects. Microcirculation 2014; 21:124-30. [DOI: 10.1111/micc.12095] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 09/23/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Hsin Hsiu
- Graduate Institute of Biomedical Engineering; National Taiwan University of Science and Technology; Taipei Taiwan
| | - Wei-Chen Hsu
- Department of Traditional Chinese Medicine; Taipei City Hospital RenAi Branch; Taipei Taiwan
| | - Yi-Fan Wu
- Graduate Institute of Biomedical Engineering; National Taiwan University of Science and Technology; Taipei Taiwan
| | - Chia-Liang Hsu
- Graduate Institute of Applied Science and Technology; National Taiwan University of Science and Technology; Taipei Taiwan
| | - Chih-Yu Chen
- Department of Obstetrics and Gynecology; Taipei City Hospital RenAi Branch; Taipei Taiwan
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152
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Yano T, Lian CS, Afroundeh R, Shirakawa K, Yunoki T. Comparison of oscillations of skin blood flow and deoxygenation in vastus lateralis in light exercise. Biol Sport 2014; 31:15-20. [PMID: 25187674 PMCID: PMC3994580 DOI: 10.5604/20831862.1083274] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2013] [Indexed: 11/23/2022] Open
Abstract
The purpose of the present study was to compare oscillation of skin blood flow with that of deoxygenation in muscle during light exercise in order to determine the physiological significance of oscillations in deoxygenation. Prolonged exercise with 50% of peak oxygen uptake was performed for 60 min. Skin blood flow (SBF) was measured using a laser blood flow meter on the right vastus lateralis muscle. Deoxygenated haemoglobin/myoglobin (DHb/Mb) concentration in the left vastus lateralis were measured using a near-infrared spectroscopy system. SBF and DHb/Mb during exercise were analysed by fast Fourier transform. We classified frequency bands according to previous studies (Kvernmo et al. 1999, Kvandal et al. 2006) into phase I (0.005-0.0095 and 0.0095-0.02 Hz), phase II (0.02-0.06 Hz: phase II) and phase III (0.06-0.16 Hz). The first peak of power spectra density (PSD) in SBF appeared at 0.0078 Hz in phase I. The second peak of PSD in SBF appeared at 0.035 Hz. The third peak of PSD in SBF appeared at 0.078 Hz. The first peak of PSD in DHb/Mb appeared at 0.0039 Hz, which was out of phase I. The second peak of PSD in DHb/Mb appeared at 0.016 Hz. The third peak of PSD in DHb/Mb appeared at 0.035 Hz. The coefficient of cross correlation was very low. Cross power spectra density showed peaks of 0.0039, 0.016 and 0.035 Hz. It is concluded that a peak of 0.016 Hz in oscillations of DHb/Mb observed in muscle during exercise is associated with endothelium-dependent vasodilation (phase I) and that a peak of 0.035 Hz in DHb/Mb is associated with sympathetic nerve activity (phase II). It is also confirmed that each peak of SBF oscillations is observed in each phase.
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Affiliation(s)
- T Yano
- Laboratory of Exercise Physiology, Faculty of Education, Hokkaido University, Kita-ku, Sapporo, Japan
| | - C-S Lian
- Laboratory of Exercise Physiology, Faculty of Education, Hokkaido University, Kita-ku, Sapporo, Japan
| | - R Afroundeh
- Laboratory of Exercise Physiology, Faculty of Education, Hokkaido University, Kita-ku, Sapporo, Japan
| | - K Shirakawa
- Laboratory of Exercise Physiology, Faculty of Education, Hokkaido University, Kita-ku, Sapporo, Japan
| | - T Yunoki
- Laboratory of Exercise Physiology, Faculty of Education, Hokkaido University, Kita-ku, Sapporo, Japan
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153
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Bruning RS, Kenney WL, Alexander LM. Altered skin flowmotion in hypertensive humans. Microvasc Res 2014; 97:81-7. [PMID: 24418051 DOI: 10.1016/j.mvr.2014.01.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2013] [Revised: 12/11/2013] [Accepted: 01/01/2014] [Indexed: 01/10/2023]
Abstract
Essential hypertensive humans exhibit attenuated cutaneous nitric oxide (NO)-dependent vasodilation. Using spectral analysis (fast Fourier transformation) we aimed to characterize the skin flowmotion contained in the laser-Doppler flowmetry recordings during local heating-induced vasodilation before and after concurrent pharmacological inhibition of nitric oxide synthase (NOS) in hypertensive and age-matched normotensive men and women. We hypothesized that hypertensive subjects would have lower total power spectral densities (PSDs), specifically in the frequency intervals associated with intrinsic endothelial and neurogenic control of the microvasculature. Furthermore, we hypothesized that NOS inhibition would attenuate the endothelial frequency interval. Laser-Doppler flowmetry recordings during local heating experiments from 18 hypertensive (MAP: 108±2mmHg) and 18 normotensive (MAP: 88±2mmHg) men and women were analyzed. Within site NO-dependent vasodilation was assessed by perfusion of a non-specific NOS inhibitor (N(G)-nitro-l-arginine methyl ester; l-NAME) through intradermal microdialysis during the heating-induced plateau in skin blood flow. Local heating-induced vasodilation increased total PSD for all frequency intervals (all p<0.001). Hypertensives had a lower total PSD (p=0.03) and absolute neurogenic frequency intervals (p<0.01) compared to the normotensives. When normalized as a percentage of total PSD, hypertensives had reduced neurogenic (p<0.001) and augmented myogenic contributions (p=0.04) to the total spectrum. NOS inhibition decreased total PSD (p<0.001) for both groups, but hypertensives exhibited lower absolute endothelial (p<0.01), neurogenic (p<0.05), and total PSD (p<0.001) frequency intervals compared to normotensives. These data suggest that essential hypertension results in altered neurogenic and NOS-dependent control of skin flowmotion and support the use of spectral analysis as a non-invasive technique to study vasoreactivity.
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Affiliation(s)
- R S Bruning
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802-6900, USA
| | - W L Kenney
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802-6900, USA
| | - L M Alexander
- Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802-6900, USA.
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154
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Wang G, Tian Y, Jia S, Zhou W, Zhang W. Pilot study of blood perfusion coherence along the meridian in forearm. Altern Ther Health Med 2013; 13:327. [PMID: 24267384 PMCID: PMC3842661 DOI: 10.1186/1472-6882-13-327] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 11/19/2013] [Indexed: 11/28/2022]
Abstract
Background Many studies have explored the relationship between skin microcirculation and meridian activation. However, few studies have examined blood perfusion coherence along the meridians, and other studies have suggested that the skin vasodilator response relates to age. This study investigated blood perfusion coherence characteristics along the meridian of the forearm in healthy volunteers. Methods A total of 15 young subjects (25.53 ± 2.20) and 15 middle-aged subjects (50.07 ± 3.37) were recruited for this study. Before experiments, each subject was placed in a temperature-controlled room for 60 min. Skin blood perfusion from five points was recorded simultaneously using a full-field laser perfusion imager before and after inflatable occlusion. The five points comprised three points located on the pericardium meridian, and two points from different locations. Coherence analysis between these points was performed at different frequency intervals from 0.0095 to 2 Hz. Results In young subjects, the coherence value was unchanged before and after occlusion, and there was no significant difference in coherence value between meridian-meridian points (M-M) and meridian-parameridian points (M-P). In middle-aged subjects, the coherence value increased significantly in both M-M and M-P at frequency intervals of 0.14-0.4 Hz, 0.4-1.6 Hz, and 1.6-2 Hz. However, there was no significant difference in coherence values between M-M and M-P. Conclusions Inflatable occlusion can increase middle-aged subjects’ blood perfusion coherence value of the forearm. However, there is no specificity in meridian location.
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155
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Webb RC, Bonifas AP, Behnaz A, Zhang Y, Yu KJ, Cheng H, Shi M, Bian Z, Liu Z, Kim YS, Yeo WH, Park JS, Song J, Li Y, Huang Y, Gorbach AM, Rogers JA. Ultrathin conformal devices for precise and continuous thermal characterization of human skin. NATURE MATERIALS 2013; 12:938-44. [PMID: 24037122 PMCID: PMC3825211 DOI: 10.1038/nmat3755] [Citation(s) in RCA: 481] [Impact Index Per Article: 43.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 08/08/2013] [Indexed: 05/11/2023]
Abstract
Precision thermometry of the skin can, together with other measurements, provide clinically relevant information about cardiovascular health, cognitive state, malignancy and many other important aspects of human physiology. Here, we introduce an ultrathin, compliant skin-like sensor/actuator technology that can pliably laminate onto the epidermis to provide continuous, accurate thermal characterizations that are unavailable with other methods. Examples include non-invasive spatial mapping of skin temperature with millikelvin precision, and simultaneous quantitative assessment of tissue thermal conductivity. Such devices can also be implemented in ways that reveal the time-dynamic influence of blood flow and perfusion on these properties. Experimental and theoretical studies establish the underlying principles of operation, and define engineering guidelines for device design. Evaluation of subtle variations in skin temperature associated with mental activity, physical stimulation and vasoconstriction/dilation along with accurate determination of skin hydration through measurements of thermal conductivity represent some important operational examples.
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Affiliation(s)
- R. Chad Webb
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Andrew P. Bonifas
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Alex Behnaz
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Yihui Zhang
- Center for Mechanics and Materials, Tsinghua University, Beijing 100084, China
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA
| | - Ki Jun Yu
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Huanyu Cheng
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA
| | - Mingxing Shi
- School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China
| | - Zuguang Bian
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA
- Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China
| | - Zhuangjian Liu
- Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Yun-Soung Kim
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Woon-Hong Yeo
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Jae Suk Park
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Jizhou Song
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, Florida 33146, USA
| | - Yuhang Li
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA
| | - Yonggang Huang
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208, USA
| | - Alexander M. Gorbach
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - John A. Rogers
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Correspondence and requests for materials should be addressed to J.A.R.
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156
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Bi R, Dong J, Lee K. Multi-channel deep tissue flowmetry based on temporal diffuse speckle contrast analysis. OPTICS EXPRESS 2013; 21:22854-61. [PMID: 24104172 DOI: 10.1364/oe.21.022854] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Recently, diffuse speckle contrast analysis (DSCA) was introduced as a competent modality for deep tissue blood flow measurement, where the speckle contrast is calculated over spatial domain on the CCD image of diffuse reflectance. In this paper, we introduce time-domain DSCA where temporal statistics are used for speckle contrast calculation and results in the same deep tissue flow measurement. This new modality is especially suitable for multi-channel real-time flowmetry, and we demonstrate its performance on human arm during cuff occlusion test. Independent component analysis (ICA) study on multi-channel data shows promising results about underlying physiology.
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157
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Iatsenko D, Bernjak A, Stankovski T, Shiogai Y, Owen-Lynch PJ, Clarkson PBM, McClintock PVE, Stefanovska A. Evolution of cardiorespiratory interactions with age. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2013; 371:20110622. [PMID: 23858485 PMCID: PMC4042892 DOI: 10.1098/rsta.2011.0622] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
We describe an analysis of cardiac and respiratory time series recorded from 189 subjects of both genders aged 16-90. By application of the synchrosqueezed wavelet transform, we extract the respiratory and cardiac frequencies and phases with better time resolution than is possible with the marked events procedure. By treating the heart and respiration as coupled oscillators, we then apply a method based on Bayesian inference to find the underlying coupling parameters and their time dependence, deriving from them measures such as synchronization, coupling directionality and the relative contributions of different mechanisms. We report a detailed analysis of the reconstructed cardiorespiratory coupling function, its time evolution and age dependence. We show that the direct and indirect respiratory modulations of the heart rate both decrease with age, and that the cardiorespiratory coupling becomes less stable and more time-variable.
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Affiliation(s)
- D. Iatsenko
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
- e-mail:
| | - A. Bernjak
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
| | - T. Stankovski
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - Y. Shiogai
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
| | - P. J. Owen-Lynch
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster LA1 4YQ, UK
| | - P. B. M. Clarkson
- Cardiology Department, Raigmore Hospital, Old Perth Road, Inverness IV2 3UJ, UK
| | | | - A. Stefanovska
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia
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158
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Tzen YT, Brienza DM, Karg PE, Loughlin PJ. Effectiveness of local cooling for enhancing tissue ischemia tolerance in people with spinal cord injury. J Spinal Cord Med 2013; 36:357-64. [PMID: 23820151 PMCID: PMC3758532 DOI: 10.1179/2045772312y.0000000085] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
OBJECTIVE To investigate the effects of localized cooling and cooling rate on pressure-induced ischemia for people with and without neurological deficits. DESIGN A 2 × 3 mixed factorial design with two groups: (1) people with spinal cord injury (SCI) and (2) people without neurological deficits (control), and three test conditions: (1) pressure only, (2) pressure with fast cooling (-4°C/min), and (3) pressure with slow cooling (-0.33°C/min). SETTING University laboratory. PARTICIPANTS Fourteen controls and 14 individuals with SCI. INTERVENTIONS Pressure on the sacrum was 0.4 kPa for 5 minutes, then 8 kPa for 20 minutes, and finally 0.4 kPa for 15 minutes. Fast and slow cooling to 25°C applied during 8 kPa of pressure. OUTCOME MEASURES Reactive hyperemia and its spectral densities in the metabolic, neurogenic, and myogenic frequency ranges. RESULTS In controls, reactive hyperemia was greater in pressure only as compared with both cooling conditions. No change was noted in all spectral densities in both cooling conditions, and only neurogenic spectral density increased without cooling. In subjects with SCI, no difference was noted in reactive hyperemia among conditions. However, metabolic and myogenic spectral densities increased without cooling and all spectral densities increased with slow cooling. No change was noted in all spectral densities with fast cooling. CONCLUSION Local cooling reduced the severity of ischemia in controls. This protective effect may be masked in subjects with SCI due to chronic microvascular changes; however, spectral analysis suggested local cooling may reduce metabolic vasodilation. These findings provide evidence towards the development of support surfaces with temperature control for weight-bearing soft tissues.
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Affiliation(s)
- Yi-Ting Tzen
- University of Pittsburgh, Pittsburgh, PA 15206, USA.
| | - David M. Brienza
- Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Patricia E. Karg
- Department of Rehabilitation Science and Technology, University of Pittsburgh, Pittsburgh, PA, USA
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159
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Roustit M, Cracowski JL. Assessment of endothelial and neurovascular function in human skin microcirculation. Trends Pharmacol Sci 2013; 34:373-84. [DOI: 10.1016/j.tips.2013.05.007] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 05/03/2013] [Accepted: 05/17/2013] [Indexed: 10/26/2022]
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160
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Hsiu H, Hsu WC, Hsu CL, Bau JG, Chen CT, Liu YS. Complexity analysis of the microcirculatory-blood-flow response following acupuncture stimulation. Microvasc Res 2013; 89:34-9. [PMID: 23806782 DOI: 10.1016/j.mvr.2013.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 05/29/2013] [Accepted: 06/13/2013] [Indexed: 10/26/2022]
Abstract
Beat-to-beat cardiovascular variability analysis provides important information on the circulatory regulatory activities. Changes in the arterial pulse transmission or the opening condition of arteriolar openings might change the fluctuation pattern of the MBF supply, and thus change the complexity property therein. We performed complexity analysis of beat-to-beat laser Doppler flowmetry (LDF) signals to study the microcirculatory-blood-flow (MBF) response at the needled site (Hegu acupoint) following acupuncture stimulation (AS). LDF signals were measured in male healthy volunteers (n=29). Each experiment involved recording a 20-minute baseline-data sequence and two sets of effects data recorded 0-20 and 50-70min after stopping AS. Approximate-entropy (ApEn) analysis, which quantifies the unpredictability of fluctuations in a time series, was performed on each 20-minute beat-to-beat LDF data sequence. The present findings indicate that AS can not only improve the local blood supply but may also increase ApEn values and decrease MBF variability parameters. This was the first attempt to apply complexity analysis to LDF signals in order to elucidate microcirculatory responses following AS. The observed results are probably attributable to the contradictory effects on the MBF supply induced by AS, which might interfere with the microcirculatory regulatory activities so as to increase the complexity of LDF signals. The present findings could help to identify the mechanism underlying the effects of AS, might aid the development of an index for monitoring the induced microcirculatory regulatory responses, and thus provide an evidence-based connection between AS and modern physiology.
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Affiliation(s)
- Hsin Hsiu
- Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
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161
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Kvandal P, Sheppard L, Landsverk SA, Stefanovska A, Kirkeboen KA. Impaired cerebrovascular reactivity after acute traumatic brain injury can be detected by wavelet phase coherence analysis of the intracranial and arterial blood pressure signals. J Clin Monit Comput 2013; 27:375-83. [PMID: 23748602 PMCID: PMC3689920 DOI: 10.1007/s10877-013-9484-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 05/14/2013] [Indexed: 11/25/2022]
Abstract
The objective of the study was to evaluate the wavelet spectral energy of oscillations in the intracranial pressure (ICP) signal in patients with acute traumatic brain injury (TBI). The wavelet phase coherence and phase shift in the 0.006-2 Hz interval between the ICP and the arterial blood pressure (ABP) signals were also investigated. Patients were separated into normal or impaired cerebrovascular reactivity, based on the pressure reactivity index (PRx). Spectral energy, phase coherence and phase shift in the low frequency and cardiorespiratory intervals were compared for the two groups. Data were prospectively collected and analyzed retrospectively in 22 patients, within the first week after acute TBI. The ICP and ABP signals were continuously recorded for [Formula: see text]40 min and the wavelet transform was used to calculate the spectral energy and phase of the signals. The average ICP wavelet energy spectrum showed distinct peaks around 1.0 (cardiac), 0.25 (respiratory) and 0.03 Hz. Patients with normal cerebrovascular reactivity (negative PRx) had 38.6 % (±SD 16.7 %) of the mean wavelet energy below the lower limit of the respiratory frequency band (0.14 Hz) compared to only 18.1 % (±SD 17.8 %) in patients with altered cerebrovascular reactivity (positive PRx) (difference: p = 0.0057). Wavelet phase coherence between the ABP and ICP signals was statistically significant (p < 0.05) in the 0.006-2 Hz interval. The phase shift between the ABP and ICP signals was around zero in the 0.14-1.0 Hz interval. Seven patients with PRx between -0.4943 and -0.1653 had a phase shift in the interval 0.07-0.14 Hz, whereas 15 patients with PRx between -0.1019 and 0.3881 had a phase shift in the interval 0.006-0.07 Hz. We conclude that the wavelet transform of the ICP signal shows spectral peaks at the cardiac, respiratory and 0.03 Hz frequencies. Normal cerebrovascular reactivity seems to be manifested as increased spectral energy in the frequency interval <0.14 Hz. A phase shift between the ICP and ABP signals in the interval 0.07-0.14 Hz indicates normal cerebrovascular reactivity, while a phase shift in the interval 0.006-0.07 Hz indicates altered cerebrovascular reactivity.
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Affiliation(s)
- Per Kvandal
- Intensive Care Unit, Oslo University Hospital, 0407 Ullevål, Oslo, Norway
| | - Lawrence Sheppard
- Physics Department, Nonlinear Biomedical Physics Group, Lancaster University, Lancaster, UK
- Present Address: Division of Ecology and Evolution, Faculty of Natural Sciences, Imperial College London, London, UK
| | - Svein A. Landsverk
- Department of Anesthesiology, Ullevål and Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Aneta Stefanovska
- Physics Department, Nonlinear Biomedical Physics Group, Lancaster University, Lancaster, UK
| | - Knut A. Kirkeboen
- Department of Anesthesiology, Ullevål and Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
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162
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Skin blood flow dynamics and its role in pressure ulcers. J Tissue Viability 2013; 22:25-36. [PMID: 23602509 DOI: 10.1016/j.jtv.2013.03.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 03/05/2013] [Accepted: 03/06/2013] [Indexed: 11/20/2022]
Abstract
Pressure ulcers are a significant healthcare problem affecting the quality of life in wheelchair bounded or bed-ridden people and are a major cost to the healthcare system. Various assessment tools such as the Braden scale have been developed to quantify the risk level of pressure ulcers. These tools have provided an initial guideline on preventing pressure ulcers while additional assessments are needed to improve the outcomes of pressure ulcer prevention. Skin blood flow function that determines the ability of the skin in response to ischemic stress has been proposed to be a good indicator for identifying people at risk of pressure ulcers. Wavelet spectral and nonlinear complexity analyses have been performed to investigate the influences of the metabolic, neurogenic and myogenic activities on microvascular regulation in people with various pathological conditions. These findings have contributed to the understanding of the role of ischemia and viability on the development of pressure ulcers. The purpose of the present review is to provide an introduction of the basic concepts and approaches for the analysis of skin blood flow oscillations, and present an overview of the research results obtained so far. We hope this information may contribute to the development of better clinical guidelines for the prevention of pressure ulcers.
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163
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Li Z, Zhang M, Xin Q, Luo S, Zhou W, Cui R, Lu L. Assessment of cerebral oxygenation oscillations in subjects with hypertension. Microvasc Res 2013; 88:32-41. [PMID: 23583904 DOI: 10.1016/j.mvr.2013.04.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 03/06/2013] [Accepted: 04/01/2013] [Indexed: 11/18/2022]
Abstract
PURPOSE The objective of this study was to assess the spontaneous oscillations in subjects with hypertension based on the wavelet transform of cerebral oxygenation signal measured with near-infrared spectroscopy (NIRS). METHODS Continuous recordings of NIRS and arterial blood pressure (ABP) signals were obtained from simultaneous measurements in 20 healthy subjects (age: 70.8±5.2 years) and 22 subjects with hypertension (age: 72.5±6.8 years). RESULTS Using spectral analysis based on wavelet transform, five frequency intervals were identified (I, 0.4-2 Hz; II, 0.15-0.4 Hz; III, 0.06-0.15 Hz; IV, 0.02-0.06 Hz and V, 0.005-0.02 Hz). The amplitudes of Δ[Hb] and Δ[HbO2] in intervals I, II and III were significantly higher in hypertensive patients, who have increased mean flow velocity in middle cerebral artery (MCA), compared to that in the healthy subjects (p<0.01). The amplitudes of the ABP in frequency intervals III and V were significantly higher in hypertensive patients than in the healthy subjects (p<0.01). CONCLUSIONS The present findings revealed that hypertension and increased mean flow velocity in MCA have significant effect on the cerebral oscillations. The higher cerebral oscillations might be related to the intracerebral atherosclerosis in response to systemic hypertension. In addition, the higher spontaneous oscillations in intervals III and V in ABP indicate a metabolic regulation and myogenic response to hypertension.
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Affiliation(s)
- Zengyong Li
- School of Mechanical Engineering, Shandong University, Jinan, 250061 PR China.
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164
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Klonizakis M, Humeau-Heurtier A. Multifractal analysis of laser Doppler flowmetry signals before and after arm-cranking exercise in an older healthy population. Med Phys 2013; 40:020702. [DOI: 10.1118/1.4774362] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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165
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Evaluate laser needle effect on blood perfusion signals of contralateral hegu acupoint with wavelet analysis. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:103729. [PMID: 23024689 PMCID: PMC3450915 DOI: 10.1155/2012/103729] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 08/01/2012] [Accepted: 08/03/2012] [Indexed: 12/15/2022]
Abstract
Our previous studies suggested that the MBF in contralateral Hegu acupoint (IL4) increased after ipsilateral Hegu acupoint was stimulated with manual acupuncture. In this study, twenty-eight (28) healthy volunteers were recruited and were randomly divided into Hegu acupoint stimulation group and Non-Hegu stimulation group. All subjects received the same model stimulation of the laser needle for 30 min in right Hegu acupoint and Non-Hegu acupoint, respectively. MBF of left LI4 was measured by the laser Doppler perfusion imaging system. The original data dealt with morlet wavelet analysis and the average amplitude and power spectral density of different frequency intervals was acquired. The results indicated that right Hegu stimulation with the laser needle might result in the increase of left Hegu acupoint MBF. 40 min later after ceased stimulation, the MBF is still increasing significantly, whereas the MBF has no significantly change in Non-Hegu stimulation group. The wavelet analysis result suggested that compared to Non-Hegu stimulation, stimulated to right Hegu acupoint might result in the increase of average amplitude in frequency intervals of 0.0095-0.02 Hz, 0.02-0.06 Hz, and 0.06-0.15 Hz, which might be influenced by the endothelial, neurogenic, and the intrinsic myogenic activity of the vessel wall, respectively.
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166
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Humeau-Heurtier A, Mahé G, Durand S, Henrion D, Abraham P. Laser speckle contrast imaging: Multifractal analysis of data recorded in healthy subjects. Med Phys 2012; 39:5849-56. [DOI: 10.1118/1.4748506] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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167
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Tikhonova IV, Tankanag AV, Chemeris NK. Age-related changes of skin blood flow during postocclusive reactive hyperemia in human. Skin Res Technol 2012; 19:e174-81. [DOI: 10.1111/j.1600-0846.2012.00624.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2012] [Indexed: 12/01/2022]
Affiliation(s)
- Irina V. Tikhonova
- Institute of Cell Biophysics; Russian Academy of Sciences; Institutskaya st. 3; Pushchino; Moscow Region; 142290; Russia
| | - Arina V. Tankanag
- Institute of Cell Biophysics; Russian Academy of Sciences; Institutskaya st. 3; Pushchino; Moscow Region; 142290; Russia
| | - Nikolay K. Chemeris
- Institute of Cell Biophysics; Russian Academy of Sciences; Institutskaya st. 3; Pushchino; Moscow Region; 142290; Russia
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168
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Dai XQ, Lu YH, Lin H, Bai L. Mechanisms of control of human skin blood flow under external pressure. BIOL RHYTHM RES 2012. [DOI: 10.1080/09291016.2011.571027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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169
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Hsiu H, Chao PT, Chiang WR, Hsu CL, Jan MY, Wang WK, Wang YYL. EFFECT OF PULSE NUMBER ON THE PULSE-BASED SYNCHRONIZED-AVERAGING ANALYSIS IN LASER DOPPLER SIGNAL. BIOMEDICAL ENGINEERING-APPLICATIONS BASIS COMMUNICATIONS 2012. [DOI: 10.4015/s1016237207000239] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Pulse parameters calculated from the LDF waveform based on a time-domain synchronized averaging analysis were shown to be able to discriminate the difference in microvascular resistance. However, its applicability may depend on the validation of signal stationarity. In this study, our aim is to investigate the effect of pulse number, which may destroy the signal stationarity, on various pulse LDF parameters. Analysis was performed in data obtained on healthy volunteers. When one pulse parameter is deviated from the standard value for more than 10%, it was regarded as an error; EP (error probability) was then defined as the occurring probability of error. It was revealed in this study that average parameter deviations for FDT and PDT were smaller than 5% for all tested pulse numbers. If we set 10% as the parameter-deviation criterion as well as the acceptable EP range, there should be at least 120 pulses for FDT and PDT, and 210 pulses for FNA and PW. The study presented here has established the criteria for appropriate pulse number to achieve the signal stationarity; we can thus get accurate pulse parameters so that the microcirculatory discriminability of the pulse-based time-averaging analysis on LDF signal can be improved. The proposed quantitative method to verify the validation of signal stationarity when utilizing time-averaging can also be applied to analysis of other bio-signals.
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Affiliation(s)
- Hsin Hsiu
- Department of Electrical Engineering, Yuan Ze University, Taoyuan, Taiwan
| | - Pin-Tsun Chao
- Biophysics Lab, Institute of Physics, Academia Sinica, Taipei, Taiwan
| | - Wen-Rei Chiang
- Department of Electrical Engineering, Yuan Ze University, Taoyuan, Taiwan
| | - Chia-Liang Hsu
- Department of Electrical Engineering, Yuan Ze University, Taoyuan, Taiwan
| | - Ming-Yie Jan
- Biophysics Lab, Institute of Physics, Academia Sinica, Taipei, Taiwan
| | - Wei-Kung Wang
- Biophysics Lab, Institute of Physics, Academia Sinica, Taipei, Taiwan
| | - Yuh-Ying Lin Wang
- Biophysics Lab, Institute of Physics, Academia Sinica, Taipei, Taiwan
- Department of Physics, National Taiwan Normal University, Taipei, Taiwan
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170
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Li Z, Zhang M, Xin Q, Chen G, Liu F, Li J. Spectral analysis of near-infrared spectroscopy signals measured from prefrontal lobe in subjects at risk for stroke. Med Phys 2012; 39:2179-85. [DOI: 10.1118/1.3696363] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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171
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Deep and surface hemodynamic signal from functional time resolved transcranial near infrared spectroscopy compared to skin flowmotion. Comput Biol Med 2012; 42:282-9. [DOI: 10.1016/j.compbiomed.2011.06.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 04/18/2011] [Accepted: 06/01/2011] [Indexed: 11/20/2022]
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172
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Li Z, Zhang M, Chen G, Luo S, Liu F, Li J. Wavelet analysis of lumbar muscle oxygenation signals during whole-body vibration: implications for the development of localized muscle fatigue. Eur J Appl Physiol 2012; 112:3109-17. [PMID: 22210560 DOI: 10.1007/s00421-011-2298-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 12/20/2011] [Indexed: 11/28/2022]
Abstract
The objective of this study was to assess the effects of whole-body vibration (WBV) on lumbar muscle oxygenation oscillations in healthy men based on the wavelet transform of near-infrared spectroscopy signals. Twelve healthy participants were exposed to WBV at frequencies of 3, 4.5 and 6 Hz while muscle oxygenation signal was monitored before, during and recovery from WBV. With spectral analysis based on wavelet transform of NIR signal, six frequency intervals were identified (I, 0.005-0.0095 Hz; II, 0.0095-0.02 Hz; III, 0.02-0.06 Hz; IV, 0.06-0.16 Hz; V, 0.16-0.40 Hz and VI, 0.40-2.0 Hz). It was found that the muscle oxygenation oscillations at 4.5 Hz in the frequency intervals I, II and III was lower during WBV compared with that of at 3 Hz. Present results demonstrated WBV at 4.5 Hz induced lower oscillatory activities than that of at 3 Hz. The lower oscillatory activities might indicate a decrease in the efficiency of oxygen supply to the oxygenated tissue and such mechanism might contribute to the development of local muscle fatigue.
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Affiliation(s)
- Zengyong Li
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong, SAR, People's Republic of China.
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173
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Wavelet analysis of acute effects of static magnetic field on resting skin blood flow at the nail wall in young men. Microvasc Res 2011; 82:277-83. [DOI: 10.1016/j.mvr.2011.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 01/14/2011] [Accepted: 03/16/2011] [Indexed: 11/22/2022]
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174
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Humeau A, Mahe G, Chapeau-Blondeau F, Rousseau D, Abraham P. Multiscale Analysis of Microvascular Blood Flow: A Multiscale Entropy Study of Laser Doppler Flowmetry Time Series. IEEE Trans Biomed Eng 2011; 58:2970-3. [DOI: 10.1109/tbme.2011.2160865] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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175
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Hsiu H, Hsu WC, Huang SM, Lin CC, Lin HW. Assessing the microcirculatory response following oral administration of Liuwei Dihuang formula by spectral analysis of skin-surface laser Doppler signals. ZHONG XI YI JIE HE XUE BAO = JOURNAL OF CHINESE INTEGRATIVE MEDICINE 2011; 9:1101-1109. [PMID: 22015192 DOI: 10.3736/jcim20111011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
OBJECTIVE This study aimed to assess the skin-surface microcirculatory effects of oral administration of Liuwei Dihuang (LW) formula by analyzing the frequency content of laser-Doppler skin blood-flow signals at important acupoints. METHODS Laser-Doppler signals were measured in male healthy volunteers in two groups of experiments: the LW experiment (n=42; aged (27.8±3.8) years) and the control experiment (n=28; aged (27.3±3.4) years). Each experiment involved a 20-minute baseline-data sequence and three following sets of effects data: recorded on the same day after oral administration of 250 mL water (28 degrees centigrade) accompanied with 5 g of LW formula (herbal extract granules), and recorded on the second day after taking other two doses of LW formula. RESULTS During the second day, the increases in the mean and pulsatile components of the flux signal were the most prominent, and the relative energy contribution at 0.02 to 0.06 Hz was significantly decreased at Taixi (KI3). There were no any other significant changes in these parameters at other measurement sites. CONCLUSION The redistribution of skin-surface microcirculatory blood flow following oral LW administration observed here can be attributed to different changes in sympathetic neural activities and thus the different perfusion resistance through the arteriolar openings of the peripheral vascular beds at different measurement sites. The developed noninvasive and real-time monitoring technique could form part of an evidence-based method for studying the physiological effects and the underlying mechanisms of traditional Chinese medicine herbs.
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Affiliation(s)
- Hsin Hsiu
- National Taiwan University of Science and Technology, Taipei, Taiwan, China.
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176
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Fractal scaling of laser Doppler flowmetry time series in patients with essential hypertension. Microvasc Res 2011; 82:291-5. [PMID: 21854788 DOI: 10.1016/j.mvr.2011.07.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 07/29/2011] [Accepted: 07/31/2011] [Indexed: 11/22/2022]
Abstract
The full diagnostic potential of the fractal complexity measure, α, of detrended fluctuation analysis (DFA) has not been realized yet. To reveal the impaired mechanisms in the blood flow regulation in patients with essential hypertension (EHT), we studied the laser Doppler flowmetry (LDF) time series by applying DFA. Forearm microvascular blood flow was measured by LDF during supine rest. After a 15 min baseline recording, microvascular response to thermal hyperemia was measured over 30 min. We found three distinct scaling regions; corresponding to the integration of local mechanisms, cardiac effect on local blood flow, and the coupling of extrinsic factors (cardiac and respiratory) to local blood flow by myogenic mechanism. In the control group, local scaling exponent, α(L)=0.96 ± 0.08, did not change but cardiac scaling exponent, α(C)=1.53 ± 0.05, for baseline signal was increased to α(CT)=1.73 ± 0.10 and cardio-respiratory scaling exponent, α(CR)=0.73 ± 0.19, was decreased to α(CRT)=0.24 ± 0.06 during vasodilatation in response to local heating. However, we found significantly different scaling exponents, α(LT)<1, α(CT) ≥ α(C)<1.5 and α(CR) ≈ α(CRT)>0.5 in patients with EHT. Our findings suggest that the local regulatory and the cushioning peripheral vascular functions are impaired in patients with EHT, and vascular/microvascular pathology can be evaluated by applying DFA to LDF signal.
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177
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Boyle M. Response to “Hypotension with acetaminophen—Maybe there is a different mechanism”. Aust Crit Care 2011. [DOI: 10.1016/j.aucc.2011.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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178
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Investigation of skin vasoreactivity and blood flow oscillations in hypertensive patients. J Hypertens 2011; 29:1569-76. [DOI: 10.1097/hjh.0b013e328348b653] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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179
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Thorn CE, Kyte H, Slaff DW, Shore AC. An association between vasomotion and oxygen extraction. Am J Physiol Heart Circ Physiol 2011; 301:H442-9. [PMID: 21602466 PMCID: PMC3154677 DOI: 10.1152/ajpheart.01316.2010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 05/12/2011] [Indexed: 02/08/2023]
Abstract
Vasomotion is defined as a spontaneous local oscillation in vascular tone whose function is unclear but may have a beneficial effect on tissue oxygenation. Optical reflectance spectroscopy and laser Doppler fluximetry provide unique insights into the possible mechanisms of vasomotion in the cutaneous microcirculation through the simultaneous measurement of changes in concentration of oxyhemoglobin ([HbO(2)]), deoxyhemoglobin ([Hb]), and mean blood saturation (S(mb)O(2)) along with blood volume and flux. The effect of vasomotion at frequencies <0.02 Hz attributed to endothelial activity was studied in the dorsal forearm skin of 24 healthy males. Fourier analysis identified periodic fluctuations in S(mb)O(2) in 19 out of 24 subjects, predominantly where skin temperatures were >29.3°C (X(2) = 6.19, P < 0.02). A consistent minimum threshold in S(mb)O(2) (mean: 39.4%, range: 24.0-50.6%) was seen to precede a sudden transient surge in flux, inducing a fast rise in S(mb)O(2). The integral increase in flux correlated with the integral increase in [HbO(2)] (Pearson's correlation r(2) = 0.50, P < 0.001) and with little change in blood volume suggests vasodilation upstream, responding to a low S(mb)O(2) downstream. This transient surge in flux was followed by a sustained period where blood volume and flux remained relatively constant and a steady decrease in [HbO(2)] and equal and opposite increase in [Hb] was considered to provide a measure of oxygen extraction. A measure of this oxygen extraction has been approximated by the mean half-life of the decay in S(mb)O(2) during this period. A comparison of the mean half-life in the 8 normal subjects [body mass index (BMI) <26.0 kg/m(2)] of 12.2 s and the 11 obese subjects (BMI >29.5 kg/m(2)) of 18.8 s was statistically significant (Mann Whitney, P < 0.004). The S(mb)O(2) fluctuated spontaneously in this saw tooth manner by an average of 9.0% (range 4.0-16.2%) from mean S(mb)O(2) values ranging from 30 to 52%. These observations support the hypothesis that red blood cells may act as sensors of local tissue hypoxia, through the oxygenation status of the hemoglobin, and initiate improved local perfusion to the tissue through hypoxic vasodilation.
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Affiliation(s)
- Clare E Thorn
- Diabetes and Vascular Medicine, Institute of Biomedical and Clinical Sciences, Peninsula College of Medicine and Dentistry, University of Exeter, National Institute for Health Research Peninsula Clinical Research Facility, Exeter, United Kingdom.
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180
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Tigno XT, Hansen BC, Nawang S, Shamekh R, Albano AM. Vasomotion becomes less random as diabetes progresses in monkeys. Microcirculation 2011; 18:429-39. [PMID: 21435082 PMCID: PMC3148284 DOI: 10.1111/j.1549-8719.2011.00103.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Please cite this paper as: Tigno, Hansen, Nawang, Shamekh, and Albano (2011). Vasomotion Becomes Less Random as Diabetes Progresses in Monkeys. Microcirculation 18(6), 429-439. ABSTRACT OBJECTIVE Changes in vasomotion may precede other global indices of autonomic dysfunction that track the onset and progression of diabetes. Recently, we showed that baseline spectral properties of vasomotion can discriminate among N, PreDM, and T2DM nonhuman primates. In this study, our aims were to: (i) determine the time dependence and complexity of the spectral properties of vasomotion in three metabolic groups of monkeys; (ii) examine the effects of heat-provoked vasodilatation on the power spectrum; and (iii) compare the effects of exogenous insulin on the vasomotion. MATERIALS AND METHODS Laser Doppler flow rates were measured from the foot in 9 N, 11 PreDM, and 7 T2DM monkeys. Baseline flow was measured at 34°C, and under heat stimulation at 44°C. Euglycemic-hyperinsulinemic clamps were performed to produce acute hyperinsulinemia. The Lempel-Ziv complexity, prediction error, and covariance complexity of five-dimensional embeddings were calculated as measures of randomness. RESULTS AND CONCLUSIONS With progression of diabetes, measures of randomness of the vasomotion progressively decreased, suggesting a progressive loss of the homeostatic capacity of the peripheral circulation to respond to environmental changes. Power spectral density among T2DM animals resided mostly in the 0- to 1.45-Hz range, which excluded the cardiac component, suggesting that with progression of the disease, regulation of flow shifts toward local rather than central (autonomic) mechanisms. Heating increased all components of the spectral power in all groups. In N, insulin increased the vasomotion contributed by endothelial, neurogenic, vascular myogenic, and respiratory processes, but diminished that due to heart rate. In contrast, in T2DM, insulin failed to stimulate the vascular myogenic and respiratory activities, but increased the neural/endothelial and heart rate components. Interestingly, acute hyperinsulinemia resulted in no significant vasomotion changes in the chronically hyperinsulinemic PreDM, suggesting yet another form of "insulin resistance" during this stage of the disease.
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Affiliation(s)
- Xenia T Tigno
- Department of Molecular Pharmacology and Physiology, College of Medicine, University of South Florida, Tampa, Florida, USA.
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181
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Drummond PD, O'Brien G. Facial nerve activity disrupts psychomotor rhythms in the forehead microvasculature. Auton Neurosci 2011; 164:105-8. [PMID: 21764650 DOI: 10.1016/j.autneu.2011.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 04/23/2011] [Accepted: 06/15/2011] [Indexed: 11/25/2022]
Abstract
Forehead blood flow was monitored in seven participants with a unilateral facial nerve lesion during relaxation, respiratory biofeedback and a sad documentary. Vascular waves at 0.1Hz strengthened during respiratory biofeedback, in tune with breathing cycles that also averaged 0.1Hz. In addition, a psychomotor rhythm at 0.15Hz was more prominent in vascular waveforms on the denervated than intact side of the forehead, both before and during relaxation and the sad documentary. These findings suggest that parasympathetic activity in the facial nerve interferes with the psychomotor rhythm in the forehead microvasculature.
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Affiliation(s)
- Peter D Drummond
- School of Psychology, Murdoch University, Perth, Western Australia, Australia.
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182
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Mohamed Yacin S, Srinivasa Chakravarthy V, Manivannan M. Reconstruction of gastric slow wave from finger photoplethysmographic signal using radial basis function neural network. Med Biol Eng Comput 2011; 49:1241-7. [PMID: 21748397 DOI: 10.1007/s11517-011-0796-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 06/25/2011] [Indexed: 10/18/2022]
Abstract
Extraction of extra-cardiac information from photoplethysmography (PPG) signal is a challenging research problem with significant clinical applications. In this study, radial basis function neural network (RBFNN) is used to reconstruct the gastric myoelectric activity (GMA) slow wave from finger PPG signal. Finger PPG and GMA (measured using Electrogastrogram, EGG) signals were acquired simultaneously at the sampling rate of 100 Hz from ten healthy subjects. Discrete wavelet transform (DWT) was used to extract slow wave (0-0.1953 Hz) component from the finger PPG signal; this slow wave PPG was used to reconstruct EGG. A RBFNN is trained on signals obtained from six subjects in both fasting and postprandial conditions. The trained network is tested on data obtained from the remaining four subjects. In the earlier study, we have shown the presence of GMA information in finger PPG signal using DWT and cross-correlation method. In this study, we explicitly reconstruct gastric slow wave from finger PPG signal by the proposed RBFNN-based method. It was found that the network-reconstructed slow wave provided significantly higher (P < 0.0001) correlation (≥ 0.9) with the subject's EGG slow wave than the correlation obtained (≈0.7) between the PPG slow wave from DWT and the EEG slow wave. Our results showed that a simple finger PPG signal can be used to reconstruct gastric slow wave using RBFNN method.
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Affiliation(s)
- S Mohamed Yacin
- Touch Lab, Biomedical Engineering Group, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, 600036, Tamilnadu, India
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183
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Abstract
This minireview discusses vasomotion, which is the oscillation in tone of blood vessels leading to flowmotion. We will briefly discuss the prevalence of vasomotion and its potential physiological and pathophysiological relevance. We will also discuss the models that have been suggested to explain how a coordinated oscillatory activity of the smooth muscle tone can occur and emphasize the role of the endothelium, the handling of intracellular Ca(2+) and the role of smooth muscle cell ion conductances. It is concluded that vasomotion is likely to enhance tissue dialysis, although this concept still requires more experimental verification, and that an understanding at the molecular level for the pathways leading to vasomotion is beginning to emerge.
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Affiliation(s)
- C Aalkjær
- Department of Physiology and Biophysics, The Water and Salt Centre, Aarhus University, Denmark.
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184
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Hsiu H, Hsu WC, Hsu CL, Huang SM. Assessing the effects of acupuncture by comparing needling the hegu acupoint and needling nearby nonacupoints by spectral analysis of microcirculatory laser Doppler signals. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2011; 2011:435928. [PMID: 21804856 PMCID: PMC3136473 DOI: 10.1093/ecam/neq073] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 05/25/2010] [Indexed: 12/13/2022]
Abstract
We aimed to assess the effects of acupuncture by analyzing the frequency content of skin blood-flow signals simultaneously recorded at the Hegu acupoint and two nearby nonacupoints following acupuncture stimulation (AS). Laser Doppler flowmetry (LDF) signals were measured in male healthy volunteers in two groups of experiments: needling the Hegu acupoint (n = 13) and needling a nearby nonacupoint (control experiment; n = 10). Each experiment involved recording a 20 min baseline-data sequence and two sets of effects data recorded 0–20 and 50–70 min after stopping AS. Wavelet transform with Morlet mother wavelet was applied to the measured LDF signals. Needling the Hegu acupoint significantly increased the blood flow, significantly decreased the relative energy contribution at 0.02–0.06 Hz and significantly increased the relative energy contribution at 0.4–1.6 Hz at Hegu, but induced no significant changes at the nonacupoints. Also, needling a nearby nonacupoint had no effect in any band at any site. This is the first time that spectral analysis has been used to investigate the microcirculatory blood-flow responses induced by AS, and has revealed possible differences in sympathetic nerve activities between needling the Hegu acupoint and its nearby nonacupoint. One possible weakness of the present design is that different De-Qi feelings following AS could lead to nonblind experimental setup, which may bias the comparison between needling Hegu and its nearby nonacupoint. Our results suggest that the described noninvasive method can be used to evaluate sympathetic control of peripheral vascular activity, which might be useful for studying the therapeutic effects of AS.
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Affiliation(s)
- Hsin Hsiu
- Graduate Institute of Biomedical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
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185
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Sheppard LW, Vuksanović V, McClintock PVE, Stefanovska A. Oscillatory dynamics of vasoconstriction and vasodilation identified by time-localized phase coherence. Phys Med Biol 2011; 56:3583-601. [PMID: 21606559 DOI: 10.1088/0031-9155/56/12/009] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We apply wavelet-based time-localized phase coherence to investigate the relationship between blood flow and skin temperature, and between blood flow and instantaneous heart rate (IHR), during vasoconstriction and vasodilation provoked by local cooling or heating of the skin. A temperature-controlled metal plate (approximately 10 cm2) placed on the volar side of the left arm was used to provide the heating and cooling. Beneath the plate, the blood flow was measured by laser Doppler flowmetry and the adjacent skin temperature by a thermistor. Two 1 h datasets were collected from each of the ten subjects. In each case a 30 min basal recording was followed by a step change in plate temperature, to either 24 °C or 42 °C. The IHR was derived from simultaneously recorded ECG. We confirm the changes in the energy and frequency of blood flow oscillations during cooling and heating reported earlier. That is, during cooling, there was a significant decrease in the average frequency of myogenic blood flow oscillations (p < 0.05) and the myogenic spectral peak became more prominent. During heating, there was a significant (p < 0.05) general increase in spectral energy, associated with vasodilation, except in the myogenic interval. Weak phase coherence between temperature and blood flow was observed for unperturbed skin, but it increased in all frequency intervals as a result of heating. It was not significantly affected by cooling. We also show that significant (p < 0.05) phase coherence exists between blood flow and IHR in the respiratory and myogenic frequency intervals. Cooling did not affect this phase coherence in any of the frequency intervals, whereas heating enhanced the phase coherence in the respiratory and myogenic intervals. This can be explained by the reduction in vascular resistance produced by heating, a process where myogenic mechanisms play a key role. We conclude that the mechanisms of vasodilation and vasoconstriction, in response to temperature change, are oscillatory in nature and are independent of central sources of variability.
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Affiliation(s)
- L W Sheppard
- Department of Physics, Lancaster University, Lancaster LA1 4YB, UK
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186
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Characterisation of very low frequency oscillations in laser Doppler perfusion signals with a singular spectrum analysis. Microvasc Res 2011; 81:239-44. [DOI: 10.1016/j.mvr.2011.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Revised: 02/03/2011] [Accepted: 02/25/2011] [Indexed: 12/12/2022]
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187
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Bernjak A, Deitrick G, Bauman W, Stefanovska A, Tuckman J. Basal sympathetic activity to the microcirculation in tetraplegic man revealed by wavelet transform of laser Doppler flowmetry. Microvasc Res 2011; 81:313-8. [DOI: 10.1016/j.mvr.2011.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 01/14/2011] [Accepted: 01/14/2011] [Indexed: 10/18/2022]
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188
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Hsiu H, Huang SM, Chen CT, Hsu CL, Hsu WC. Acupuncture stimulation causes bilaterally different microcirculatory effects in stroke patients. Microvasc Res 2011; 81:289-94. [DOI: 10.1016/j.mvr.2011.03.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 02/17/2011] [Accepted: 03/02/2011] [Indexed: 10/18/2022]
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189
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Clough GF, L'Esperance V, Turzyniecka M, Walter L, Chipperfield AJ, Gamble J, Krentz AJ, Byrne CD. Functional dilator capacity is independently associated with insulin sensitivity and age in central obesity and is not improved by high dose statin treatment. Microcirculation 2011; 18:74-84. [PMID: 21166928 DOI: 10.1111/j.1549-8719.2010.00070.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To test the hypothesis that: (i) functional microvascular dilator capacity is independently associated with insulin sensitivity and age in individuals with central adiposity at risk of cardiovascular disease (CVD); and (ii) functional microvascular dilator capacity is improved by high dose statin treatment. METHODS Functional dilator capacity (measured as change in laser Doppler blood flux from baseline during post occlusive reactive hyperemia [peak flux%resting flux; PF%RF] and flowmotion (power spectral density [PSD] analysis)) were assessed in 40 people with central adiposity and one or more other CVD risk factors. Measurements were made at rest and during acute hyperinsulinaemia before and six months after high dose atorvastatin (40 mg daily) or placebo. RESULTS Insulin-induced change in PF%RF was independently associated with insulin sensitivity (M/I) (r = 0.46 p = 0.02) and age (r = -0.46 p = 0.02), which together explained almost half of the variance in PF%RF (adjusted r² = 0.37, p = 0.008). Whilst atorvastatin decreased LDL cholesterol by 51% (p < 0.001), PF%RF and flowmotion remained unchanged. CONCLUSIONS Insulin sensitivity and age are independently associated with an insulin-induced change in functional microvascular dilator capacity in individuals with central adiposity at risk of CVD. Dilator capacity is not improved by six months high dose statin treatment.
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Affiliation(s)
- Geraldine F Clough
- Institute of Developmental Sciences, School of Medicine, University of Southampton, Southampton General Hospital (MP 887), Southampton, UK.
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190
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Dynamic microvascular blood flow analysis during post-occlusive reactive hyperemia test in patients with schizophrenia. Ann Biomed Eng 2011; 39:1972-83. [PMID: 21445693 DOI: 10.1007/s10439-011-0294-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 03/03/2011] [Indexed: 10/18/2022]
Abstract
Patients suffering from schizophrenia have an increased mortality risk due to cardiovascular events. Recently the analysis of peripheral circulation has revealed interesting results in the study of vascular pathological conditions assuming that the state of microcirculation of the skin is at least partly representative for the constitution of other vascular beds including those of the cardiac muscle and arteries. The objective of this study was to investigate the microcirculation in patients with acute schizophrenia (PAT, n = 15, mean age 33.0 years, 7 male, 8 female) to identify whether spectral features from blood flow signals derived through laser Doppler spectrometry are significantly altered compared to healthy subjects (CON, n = 15, mean age 32.4 years, 7 male, 8 female) by means of the post-occlusive reactive hyperemia test. It was also explored if a segmentation of the post-ischemic stage can disclose more detailed and additional information about the dynamic behavior of the blood flow during hyperemic response. For this reason, time-frequency analyses were performed to observe the course of the blood flow frequency components over time. Our results indicate significant differences in the patients group, already detectable under baseline conditions but also in the hyperemic phase. The main modifications affect the respiratory (p = 0.006) as well as the cardiac (p = 0.001) activity. It was further shown that the application of a segmented analysis of the post-ischemic state considerably improves the differentiation between both groups. Only with the introduced segmentation algorithm using a window length of 2048 samples and a shift of 128 and 256 samples we could demonstrate influences of the disease on the endothelial (p = 0.029), the sympathetic (p = 0.019) and the myogenic (p = 0.029) mechanisms. These information provide further insights into the appearance of schizophrenia and could lead to an improvement of the patients' treatment to avoid the occurrence of cardiovascular events.
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191
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Boyle M, Lau A, Nicholson L, O'Brien M, Flynn G, Collins D, Walsh W, Bihari D. Paracetamol-induced skin blood flow and blood pressure changes. Crit Care 2011. [PMCID: PMC3067019 DOI: 10.1186/cc9765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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192
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Pradhan RK, Chakravarthy VS. Informational dynamics of vasomotion in microvascular networks: a review. Acta Physiol (Oxf) 2011; 201:193-218. [PMID: 20887358 DOI: 10.1111/j.1748-1716.2010.02198.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Vasomotion refers to spontaneous oscillation of small vessels observed in many microvascular beds. It is an intrinsic phenomenon unrelated to cardiac rhythm or neural and hormonal regulation. Vasomotion is found to be particularly prominent under conditions of metabolic stress. In spite of a significant existent literature on vasomotion, its physiological and pathophysiological roles are not clear. It is thought that modulation of vasomotion by vasoactive substances released by metabolizing tissue plays a role in ensuring optimal delivery of nutrients to the tissue. Vasomotion rhythms exhibit a great variety of temporal patterns from regular oscillations to chaos. The nature of vasomotion rhythm is believed to be significant to its function, with chaotic vasomotion offering several physiological advantages over regular, periodic vasomotion. In this article, we emphasize that vasomotion is best understood as a network phenomenon. When there is a local metabolic demand in tissue, an ideal vascular response should extend beyond local microvasculature, with coordinated changes over multiple vascular segments. Mechanisms of information transfer over a vessel network have been discussed in the literature. The microvascular system may be regarded as a network of dynamic elements, interacting, either over the vascular anatomical network via gap junctions, or physiologically by exchange of vasoactive substances. Drawing analogies with spatiotemporal patterns in neuronal networks of central nervous system, we ask if properties like synchronization/desynchronization of vasomotors have special significance to microcirculation. Thus the contemporary literature throws up a novel view of microcirculation as a network that exhibits complex, spatiotemporal and informational dynamics.
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Affiliation(s)
- R K Pradhan
- Biotechnology and Bioengineering Center, Medical College of Wisconsin, Milwaukee, WI 53226-6509, USA.
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193
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Liu WM, Meyer J, Scully CG, Elster E, Gorbach AM. Observing temperature fluctuations in humans using infrared imaging. QUANTITATIVE INFRARED THERMOGRAPHY JOURNAL 2011; 8:21-36. [PMID: 23538682 PMCID: PMC3607327 DOI: 10.3166/qirt.8.21-36] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this work we demonstrate that functional infrared imaging is capable of detecting low frequency temperature fluctuations in intact human skin and revealing spatial, temporal, spectral, and time-frequency based differences among three tissue classes: microvasculature, large sub-cutaneous veins, and the remaining surrounding tissue of the forearm. We found that large veins have stronger contractility in the range of 0.005-0.06 Hz compared to the other two tissue classes. Wavelet phase coherence and power spectrum correlation analysis show that microvasculature and skin areas without vessels visible by IR have high phase coherence in the lowest three frequency ranges (0.005-0.0095 Hz, 0.0095-0.02 Hz, and 0.02-0.06 Hz), whereas large veins oscillate independently.
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Affiliation(s)
- Wei-Min Liu
- Naval Medical Research Center, Silver Spring, MD, USA ; National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
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194
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Humeau A, Buard B, Mahé G, Chapeau-Blondeau F, Rousseau D, Abraham P. Multifractal analysis of heart rate variability and laser Doppler flowmetry fluctuations:comparison of results from different numerical methods. Phys Med Biol 2010; 55:6279-97. [DOI: 10.1088/0031-9155/55/20/015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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195
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On non-invasive measurement of gastric motility from finger photoplethysmographic signal. Ann Biomed Eng 2010; 38:3744-55. [PMID: 20614246 DOI: 10.1007/s10439-010-0113-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 06/22/2010] [Indexed: 10/19/2022]
Abstract
This article investigates the possibility of extracting gastric motility (GM) information from finger photoplethysmographic (PPG) signals non-invasively. Now-a-days measuring GM is a challenging task because of invasive and complicated clinical procedures involved. It is well-known that the PPG signal acquired from finger consists of information related to heart rate and respiratory rate. This thread is taken further and effort has been put here to find whether it is possible to extract GM information from finger PPG in an easier way and without discomfort to the patients. Finger PPG and GM (measured using Electrogastrogram, EGG) signals were acquired simultaneously at the rate of 100 Hz from eight healthy subjects for 30 min duration in fasting and postprandial states. In this study, we process the finger PPG signal and extract a slow wave that is analogous to actual EGG signal. To this end, we chose two advanced signal processing approaches: first, we perform discrete wavelet transform (DWT) to separate the different components, since PPG and EGG signals are non-stationary in nature. Second, in the frequency domain, we perform cross-spectral and coherence analysis using autoregressive (AR) spectral estimation method in order to compare the spectral details of recorded PPG and EGG signals. In DWT, a lower frequency oscillation (≈0.05 Hz) called slow wave was extracted from PPG signal which looks similar to the slow wave of GM in both shape and frequency in the range (0-0.1953) Hz. Comparison of these two slow wave signals was done by normalized cross-correlation technique. Cross-correlation values are found to be high (range 0.68-0.82, SD 0.12, R = 1.0 indicates exact agreement, p < 0.05) for all subjects and there is no significant difference in cross-correlation between fasting and postprandial states. The coherence analysis results demonstrate that a moderate coherence (range 0.5-0.7, SD 0.13, p < 0.05) exists between EGG and PPG signal in the "slow wave" frequency band, without any significant change in the level of coherence in postprandial state. These results indicate that finger PPG signal contains GM-related information. The findings are sufficiently encouraging to motivate further exploration of finger PPG as a non-invasive source of GM-related information.
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196
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Tikhonova IV, Tankanag AV, Chemeris NK. Time–amplitude analysis of skin blood flow oscillations during the post-occlusive reactive hyperemia in human. Microvasc Res 2010; 80:58-64. [DOI: 10.1016/j.mvr.2010.03.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 03/01/2010] [Accepted: 03/17/2010] [Indexed: 10/19/2022]
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197
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Pointwise Hölder exponents of a model for skin laser Doppler flowmetry signals based on six nonlinear coupled oscillators with linear and parametric couplings: Comparison with experimental data from young healthy subjects. Ing Rech Biomed 2010. [DOI: 10.1016/j.irbm.2009.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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198
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Buard B, Mahé G, Chapeau-Blondeau F, Rousseau D, Abraham P, Humeau A. Generalized fractal dimensions of laser Doppler flowmetry signals recorded from glabrous and nonglabrous skin. Med Phys 2010; 37:2827-36. [DOI: 10.1118/1.3395577] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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199
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Hsiu H, Hsu WC, Chen BH, Hsu CL. Differences in the microcirculatory effects of local skin surface contact pressure stimulation between acupoints and nonacupoints: possible relevance to acupressure. Physiol Meas 2010; 31:829-41. [PMID: 20479520 DOI: 10.1088/0967-3334/31/6/007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In the present study, laser Doppler measurement was used to quantitatively investigate the microcirculatory effects of contact pressure stimulation (PS) underneath the Hoku acupoint and its nearby nonacupoint, to improve the understanding of the mechanisms underlying acupressure therapy. A control group (no PS applied) and three experimental groups with different applied PS (group A, 60 mmHg on the Hoku acupoint; group B, 60 mmHg on a nearby nonacupoint; group C, 50 mmHg on a nearby nonacupoint) were studied. Each experiment involved recording data of a 20 min baseline and two periods of effects after stopping PS. The relative energy contribution (REC) in five frequency bands, as revealed by Morlet wavelet transformation, was calculated. At the pressed site, the average value of the laser Doppler flux signal was increased only in group A, and coefficient of variance of the amplitude sequence was only significantly decreased during measurement (M1: 0 to 20 min) in group B. The RECs of the myogenic-related band were significantly increased in groups A and C, whereas there were no significant changes found in group B. The improved microcirculatory blood-flow perfusion at Hoku may partly explain why acupressure can exert better therapeutic effects than PS applied to other sites. The laser Doppler spectra responses illustrated that the induced pressure-induced vasodilation can be attributed mainly to the myogenic response. Laser Doppler measurement and analysis therefore represent a noninvasive method of examining the microcirculatory efficacy of acupressure therapy.
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Affiliation(s)
- Hsin Hsiu
- Department of Electrical Engineering, Yuan Ze University, No. 135, Rd Yuan-Tung, Taoyuan, Taiwan, Republic of China.
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200
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Recovery of 0.1Hz microvascular skin blood flow in dysautonomic diabetic (type 2) neuropathy by using Frequency Rhythmic Electrical Modulation System (FREMS). Med Eng Phys 2010; 32:407-13. [DOI: 10.1016/j.medengphy.2010.02.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 12/21/2009] [Accepted: 02/03/2010] [Indexed: 11/22/2022]
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