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Shali RK, Setarehdan SK, Seifi B. Functional near-infrared spectroscopy based blood pressure variations and hemodynamic activity of brain monitoring following postural changes: A systematic review. Physiol Behav 2024; 281:114574. [PMID: 38697274 DOI: 10.1016/j.physbeh.2024.114574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 04/03/2024] [Accepted: 04/26/2024] [Indexed: 05/04/2024]
Abstract
Postural change from supine or sitting to standing up leads to displacement of 300 to 1000 mL of blood from the central parts of the body to the lower limb, which causes a decrease in venous return to the heart, hence decrease in cardiac output, causing a drop in blood pressure. This may lead to falling down, syncope, and in general reducing the quality of daily activities, especially in the elderly and anyone suffering from nervous system disorders such as Parkinson's or orthostatic hypotension (OH). Among different modalities to study brain function, functional near-infrared spectroscopy (fNIRS) is a neuroimaging method that optically measures the hemodynamic response in brain tissue. Concentration changes in oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (HHb) are associated with brain neural activity. fNIRS is significantly more tolerant to motion artifacts compared to fMRI, PET, and EEG. At the same time, it is portable, has a simple structure and usage, is safer, and much more economical. In this article, we systematically reviewed the literature to examine the history of using fNIRS in monitoring brain oxygenation changes caused by sudden changes in body position and its relationship with the blood pressure changes. First, the theory behind brain hemodynamics monitoring using fNIRS and its advantages and disadvantages are presented. Then, a study of blood pressure variations as a result of postural changes using fNIRS is described. It is observed that only 58 % of the references concluded a positive correlation between brain oxygenation changes and blood pressure changes. At the same time, 3 % showed a negative correlation, and 39 % did not show any correlation between them.
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Affiliation(s)
- Roya Kheyrkhah Shali
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran.
| | - Seyed Kamaledin Setarehdan
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Behjat Seifi
- Faculty of Medical Science, University of Tehran, Tehran, Iran
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2
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Lenka A, Lamotte G, Beach P. Asymptomatic orthostatic hypotension in synucleinopathies: to treat or not to treat? Clin Auton Res 2024; 34:25-29. [PMID: 38079008 DOI: 10.1007/s10286-023-01006-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Accepted: 10/21/2023] [Indexed: 03/17/2024]
Affiliation(s)
- Abhishek Lenka
- Parkinson's Disease Center and Movement Disorders Clinic, Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Guillaume Lamotte
- Department of Neurology, University of Utah, Salt Lake City, UT, USA.
- Department of Neurology, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.
| | - Paul Beach
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
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Klop M, de Heus RAA, Maier AB, van Alphen A, Floor-Westerdijk MJ, Bronkhorst M, Melis RJF, Meskers CGM, Claassen JAHR, van Wezel RJA. Capturing postural blood pressure dynamics with near-infrared spectroscopy-measured cerebral oxygenation. GeroScience 2023; 45:2643-2657. [PMID: 37041313 PMCID: PMC10651596 DOI: 10.1007/s11357-023-00791-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 03/31/2023] [Indexed: 04/13/2023] Open
Abstract
Orthostatic hypotension (OH) is highly prevalent in older adults and associated with dizziness, falls, lower physical and cognitive function, cardiovascular disease, and mortality. OH is currently diagnosed in a clinical setting with single-time point cuff measurements. Continuous blood pressure (BP) devices can measure OH dynamics but cannot be used for daily life monitoring. Near-infrared spectroscopy (NIRS) has potential diagnostic value in measuring cerebral oxygenation continuously over a longer time period, but this needs further validation. This study aimed to compare NIRS-measured (cerebral) oxygenation with continuous BP and transcranial Doppler-measured cerebral blood velocity (CBv) during postural changes. This cross-sectional study included 41 participants between 20 and 88 years old. BP, CBv, and cerebral (long channels) and superficial (short channels) oxygenated hemoglobin (O2Hb) were measured continuously during various postural changes. Pearson correlations between BP, CBv, and O2Hb were calculated over curves and specific characteristics (maximum drop amplitude and recovery). BP and O2Hb only showed good curve-based correlations (0.58-0.75) in the initial 30 s after standing up. Early (30-40 s) and 1-min BP recovery associated significantly with O2Hb, but no consistent associations were found for maximum drop amplitude and late (60-175 s) recovery values. Associations between CBv and O2Hb were poor, but stronger for long-channel than short-channel measurements. BP associated well with NIRS-measured O2Hb in the first 30 s after postural change. Stronger associations for CBv with long-channel O2Hb suggest that long-channel NIRS specifically reflects cerebral blood flow during postural transitions, necessary to better understand the consequences of OH such as intolerance symptoms.
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Affiliation(s)
- Marjolein Klop
- Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands.
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, the Netherlands.
| | - Rianne A A de Heus
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Andrea B Maier
- Department of Human Movement Sciences, @AgeAmsterdam, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
- Healthy Longevity Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Centre for Healthy Longevity, @AgeSingapore, National University Health System, Singapore, Singapore
| | - Anne van Alphen
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | | | - René J F Melis
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Carel G M Meskers
- Department of Rehabilitation Medicine, Amsterdam Movement Sciences, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Jurgen A H R Claassen
- Department of Geriatric Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Richard J A van Wezel
- Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands
- Department of Biomedical Signals and Systems, Technical Medical Centre, University of Twente, Enschede, the Netherlands
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Pérez-Denia L, Claffey P, O'Reilly A, Delgado-Ortet M, Rice C, Kenny RA, Finucane C. Cerebral Oxygenation Responses to Standing in Young Patients with Vasovagal Syncope. J Clin Med 2023; 12:4202. [PMID: 37445237 DOI: 10.3390/jcm12134202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 07/15/2023] Open
Abstract
Vasovagal syncope (VVS) is common in young adults and is attributed to cerebral hypoperfusion. However, during active stand (AS) testing, only peripheral and not cerebral hemodynamic responses are measured. We sought to determine whether cerebral oxygenation responses to an AS test were altered in young VVS patients when compared to the young healthy controls. A sample of young healthy adults and consecutive VVS patients attending a Falls and Syncope unit was recruited. Continuous beat-to-beat blood pressure (BP), heart rate, near-infrared spectroscopy (NIRS)-derived tissue saturation index (TSI), and changes in concentration of oxygenated/deoxygenated Δ[O2Hb]/Δ[HHb] hemoglobin were measured. BP and NIRS-derived features included nadir, peak, overshoot, trough, recovery rate, normalized recovery rate, and steady-state. Multivariate linear regression was used to adjust for confounders and BP. In total, 13 controls and 27 VVS patients were recruited. While no significant differences were observed in the TSI and Δ[O2Hb], there was a significantly smaller Δ[HHb] peak-to-trough and faster Δ[HHb] recovery rate in VVS patients, independent of BP. A higher BP steady-state was observed in patients but did not remain significant after multiple comparison correction. Young VVS patients demonstrated a similar cerebral circulatory response with signs of altered peripheral circulation with respect to the controls, potentially due to a hyper-reactive autonomic nervous system. This study sets the grounds for future investigations to understand the role of cerebral regulation during standing in VVS.
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Affiliation(s)
- Laura Pérez-Denia
- School of Medicine, Trinity College Dublin, D02 K6K6 Dublin, Ireland
- Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 TYF3 Dublin, Ireland
- Department of Medical Physics, Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 C9X2 Dublin, Ireland
| | - Paul Claffey
- School of Medicine, Trinity College Dublin, D02 K6K6 Dublin, Ireland
- Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 TYF3 Dublin, Ireland
| | - Ailbhe O'Reilly
- Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 TYF3 Dublin, Ireland
- Department of Bioengineering, School of Mechanical Engineering, Trinity College Dublin, D02 PN40 Dublin, Ireland
| | | | - Ciara Rice
- Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 TYF3 Dublin, Ireland
| | - Rose Anne Kenny
- School of Medicine, Trinity College Dublin, D02 K6K6 Dublin, Ireland
- Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 TYF3 Dublin, Ireland
| | - Ciarán Finucane
- School of Medicine, Trinity College Dublin, D02 K6K6 Dublin, Ireland
- Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 TYF3 Dublin, Ireland
- Department of Medical Physics, Mercer's Institute for Successful Ageing, St. James's Hospital Dublin, D08 C9X2 Dublin, Ireland
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Nordine M, Treskatsch S, Habazettl H, Gunga HC, Brauns K, Dosel P, Petricek J, Opatz O. Orthostatic Resiliency During Successive Hypoxic, Hypoxic Orthostatic Challenge: Successful vs. Unsuccessful Cardiovascular and Oxygenation Strategies. Front Physiol 2021; 12:712422. [PMID: 34776997 PMCID: PMC8578448 DOI: 10.3389/fphys.2021.712422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 10/06/2021] [Indexed: 11/25/2022] Open
Abstract
Introduction: Rapid environmental changes, such as successive hypoxic-hypoxic orthostatic challenges (SHHOC) occur in the aerospace environment, and the ability to remain orthostatically resilient (OR) relies upon orchestration of physiological counter-responses. Counter-responses adjusting for hypoxia may conflict with orthostatic responses, and a misorchestration can lead to orthostatic intolerance (OI). The goal of this study was to pinpoint specific cardiovascular and oxygenation factors associated with OR during a simulated SHHOC. Methods: Thirty one men underwent a simulated SHHOC consisting of baseline (P0), normobaric hypoxia (Fi02 = 12%, P1), and max 60 s of hypoxic lower body negative pressure (LBNP, P2). Alongside anthropometric variables, non-invasive cardiovascular, central and peripheral tissue oxygenation parameters, were recorded. OI was defined as hemodynamic collapse during SHHOC. Comparison of anthropometric, cardiovascular, and oxygenation parameters between OR and OI was performed via Student’s t-test. Within groups, a repeated measures ANOVA test with Holm-Sidak post hoc test was performed. Performance diagnostics were performed to assess factors associated with OR/OI (sensitivity, specificity, positive predictive value PPV, and odd’s ratio OR). Results: Only 9/31 were OR, and 22/31 were OI. OR had significantly greater body mass index (BMI), weight, peripheral Sp02, longer R-R Interval (RRI) and lower heart rate (HR) at P0. During P1 OR exhibited significantly higher cardiac index (CI), stroke volume index (SVI), and lower systemic vascular resistance index (SVRI) than OI. Both groups exhibited a significant decrease in cerebral oxygenation (TOIc) with an increase in cerebral deoxygenated hemoglobin (dHbc), while the OI group showed a significant decrease in cerebral oxygenated hemoglobin (02Hbc) and peripheral oxygenation (TOIp) with an increase in peripheral deoxygenated hemoglobin (dHbp). During P2, OR maintained significantly greater CI, systolic, mean, and diastolic pressure (SAP, MAP, DAP), with a shortened RRI compared to the OI group, while central and peripheral oxygenation were not different. Body weight and BMI both showed high sensitivity (0.95), low specificity (0.33), a PPV of 0.78, with an OR of 0.92, and 0.61. P0 RRI showed a sensitivity of 0.95, specificity of 0.22, PPV 0.75, and OR of 0.99. Delta SVI had the highest performance diagnostics during P1 (sensitivity 0.91, specificity 0.44, PPV 0.79, and OR 0.8). Delta SAP had the highest overall performance diagnostics for P2 (sensitivity 0.95, specificity 0.67, PPV 0.87, and OR 0.9). Discussion: Maintaining OR during SHHOC is reliant upon greater BMI, body weight, longer RRI, and lower HR at baseline, while increasing CI and SVI, minimizing peripheral 02 utilization and decreasing SVRI during hypoxia. During hypoxic LBNP, the ability to remain OR is dependent upon maintaining SAP, via CI increases rather than SVRI. Cerebral oxygenation parameters, beyond 02Hbc during P1 did not differ between groups, suggesting that the during acute hypoxia, an increase in cerebral 02 consumption, coupled with increased peripheral 02 utilization does seem to play a role in OI risk during SHHOC. However, cardiovascular factors such as SVI are of more value in assessing OR/OI risk. The results can be used to implement effective aerospace crew physiological monitoring strategies.
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Affiliation(s)
- Michael Nordine
- Department of Anaesthesiology and Intensive Care Medicine, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sascha Treskatsch
- Department of Anaesthesiology and Intensive Care Medicine, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Helmut Habazettl
- Center for Space Medicine and Extreme Environments Berlin, Berlin Institute of Health, Institute of Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Hanns-Christian Gunga
- Center for Space Medicine and Extreme Environments Berlin, Berlin Institute of Health, Institute of Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Katharins Brauns
- Center for Space Medicine and Extreme Environments Berlin, Berlin Institute of Health, Institute of Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Petr Dosel
- Military University Hospital, Institute of Aviation Medicine, Prague, Czechia
| | - Jan Petricek
- Military University Hospital, Institute of Aviation Medicine, Prague, Czechia
| | - Oliver Opatz
- Center for Space Medicine and Extreme Environments Berlin, Berlin Institute of Health, Institute of Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
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The influence of short-term high-altitude acclimatization on cerebral and leg tissue oxygenation post-orthostasis. Eur J Appl Physiol 2021; 121:3095-3102. [PMID: 34319446 DOI: 10.1007/s00421-021-04765-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 07/06/2021] [Indexed: 10/20/2022]
Abstract
PURPOSE Orthostasis at sea level decreases brain tissue oxygenation and increases risk of syncope. High altitude reduces brain and peripheral muscle tissue oxygenation. This study determined the effect of short-term altitude acclimatization on cerebral and peripheral leg tissue oxygenation index (TOI) post-orthostasis. METHOD Seven lowlanders completed a supine-to-stand maneuver at sea level (450 m) and for 3 consecutive days at high altitude (3776 m). Cardiorespiratory measurements and near-infrared spectroscopy-derived oxygenation of the frontal lobe (cerebral TOI) and vastus lateralis (leg TOI) were measured at supine and 5-min post-orthostasis. RESULTS After orthostasis at sea level, cerebral TOI decreased [mean Δ% (95% confidential interval): - 4.5%, (- 7.5, - 1.5), P < 0.001], whilst leg TOI was unchanged [- 4.6%, (- 10.9, 1.7), P = 0.42]. High altitude had no effect on cerebral TOI following orthostasis [days 1-3: - 2.3%, (- 5.3, 0.7); - 2.4%, (- 5.4, 0.6); - 2.1%, (- 5.1, 0.9), respectively, all P > 0.05], whereas leg TOI decreased [days 1-3: - 12.0%, (- 18.3, - 5.7); - 12.1%, (- 18.4, - 5.8); - 10.2%, (- 16.5, - 3.9), respectively, all P < 0.001]. This response did not differ with days spent at high altitude, despite evidence of cardiorespiratory acclimatization [increased peripheral oxygen saturation (supine: P = 0.01; stand: P = 0.02) and decreased end-tidal carbon dioxide (supine: P = 0.003; stand: P = 0.01)]. CONCLUSION Cerebral oxygenation is preferentially maintained over leg oxygenation post-orthostasis at high altitude, suggesting different vascular regulation between cerebral and peripheral circulations. Short-term acclimatization to high altitude did not alter cerebral and leg oxygenation responses to orthostasis.
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Xia X, Wang R, Vetrano DL, Grande G, Laukka EJ, Ding M, Fratiglioni L, Qiu C. From Normal Cognition to Cognitive Impairment and Dementia: Impact of Orthostatic Hypotension. Hypertension 2021; 78:769-778. [PMID: 34225472 PMCID: PMC8357050 DOI: 10.1161/hypertensionaha.121.17454] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Supplemental Digital Content is available in the text. The role of orthostatic hypotension (OH) in the continuum of cognitive aging remains to be clarified. We sought to investigate the associations of OH with dementia, cognitive impairment, no dementia (CIND), and CIND progression to dementia in older adults while considering orthostatic symptoms. This population-based cohort study included 2532 baseline (2001–2004) dementia-free participants (age ≥60 years; 62.6% women) in the SNAC-K (Swedish National Study on Aging and Care in Kungsholmen) who were regularly examined over 12 years. We further divided the participants into a baseline CIND-free cohort and a CIND cohort. OH was defined as a decrease by ≥20/10 mm Hg in systolic/diastolic blood pressure upon standing and further divided into asymptomatic and symptomatic OH. Dementia was diagnosed following the international criteria. CIND was defined as scoring ≥1.5 SDs below age group-specific means in ≥1 cognitive domain. Data were analyzed with flexible parametric survival models, controlling for confounding factors. Of the 2532 participants, 615 were defined with OH at baseline, and 322 were diagnosed with dementia during the entire follow-up period. OH was associated with an adjusted hazard ratio of 1.40 for dementia (95% CI, 1.10–1.76), 1.15 (0.94–1.40) for CIND, and 1.54 (1.05–2.25) for CIND progression to dementia. The associations of dementia and CIND progression to dementia with asymptomatic OH were similar to overall OH, whereas symptomatic OH was only associated with CIND progression to dementia. Our study suggests that OH, even asymptomatic OH, is associated with increased risk of dementia and accelerated progression from CIND to dementia in older adults.
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Affiliation(s)
- Xin Xia
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.)
| | - Rui Wang
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.).,The Swedish School of Sport and Health Sciences, GIH, Stockholm, Sweden (R.W.).,Department of Medicine and Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison (R.W.)
| | - Davide L Vetrano
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.).,Department of Geriatrics, Catholic University of Rome, Italy (D.L.V.).,Centro di Medicina dell'Invecchiamento, Fondazione Policlinico A. Gemelli, Rome, Italy (D.L.V.)
| | - Giulia Grande
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.)
| | - Erika J Laukka
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.).,Stockholm Gerontology Research Center, Sweden (E.J.L., L.F.)
| | - Mozhu Ding
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.).,Unit of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (M.D.)
| | - Laura Fratiglioni
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.).,Stockholm Gerontology Research Center, Sweden (E.J.L., L.F.)
| | - Chengxuan Qiu
- Aging Research Center, Department of Neurobiology, Care Sciences and Society (NVS), Karolinska Institutet-Stockholm University, Sweden (X.X., R.W., D.L.V., G.G., E.J.L., M.D., L.F., C.Q.)
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Rocha EA, Mehta N, Távora-Mehta MZP, Roncari CF, Cidrão AADL, Elias Neto J. Dysautonomia: A Forgotten Condition - Part II. Arq Bras Cardiol 2021; 116:981-998. [PMID: 34008826 PMCID: PMC8121459 DOI: 10.36660/abc.20200422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 11/04/2020] [Indexed: 12/15/2022] Open
Affiliation(s)
- Eduardo Arrais Rocha
- Hospital Universitário Walter Cantídio da Universidade Federal do Ceará (UFC) - Programa de Pós-graduação em Ciências Cardiovasculares da Faculdade de Medicina da UFC, Fortaleza, CE - Brasil
| | - Niraj Mehta
- Universidade Federal do Paraná, Curitiba, PR - Brasil.,Clínica de Eletrofisiologia do Paraná, Curitiba, PR - Brasil
| | | | - Camila Ferreira Roncari
- Departamento de Fisiologia e Farmacologia - Faculdade de Medicina da Universidade Federal do Ceará (UFC), Fortaleza, CE - Brasil
| | - Alan Alves de Lima Cidrão
- Programa de Pós-graduação em Ciências Cardiovasculares da Faculdade de Medicina da UFC, Fortaleza, CE - Brasil
| | - Jorge Elias Neto
- Serviço de Eletrofisiologia do Vitória Apart Hospital, Vitória, ES - Brasil
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Harms MPM, Finucane C, Pérez-Denia L, Juraschek SP, van Wijnen VK, Lipsitz LA, van Lieshout JJ, Wieling W. Systemic and cerebral circulatory adjustment within the first 60 s after active standing: An integrative physiological view. Auton Neurosci 2021; 231:102756. [PMID: 33385733 PMCID: PMC8103784 DOI: 10.1016/j.autneu.2020.102756] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/30/2020] [Accepted: 11/22/2020] [Indexed: 02/07/2023]
Abstract
Transient cardiovascular and cerebrovascular responses within the first minute of active standing provide the means to assess autonomic, cardiovascular and cerebrovascular regulation using a real-world everyday stimulus. Traditionally, these responses have been used to detect autonomic dysfunction, and to identify the hemodynamic correlates of patient symptoms and attributable causes of (pre)syncope and falls. This review addresses the physiology of systemic and cerebrovascular adjustment within the first 60 s after active standing. Mechanical factors induced by standing up cause a temporal mismatch between cardiac output and vascular conductance which leads to an initial blood pressure drops with a nadir around 10 s. The arterial baroreflex counteracts these initial blood pressure drops, but needs 2-3 s to be initiated with a maximal effect occurring at 10 s after standing while, in parallel, cerebral autoregulation buffers these changes within 10 s to maintain adequate cerebral perfusion. Interestingly, both the magnitude of the initial drop and these compensatory mechanisms are thought to be quite well-preserved in healthy aging. It is hoped that the present review serves as a reference for future pathophysiological investigations and epidemiological studies. Further experimental research is needed to unravel the causal mechanisms underlying the emergence of symptoms and relationship with aging and adverse outcomes in variants of orthostatic hypotension.
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Affiliation(s)
- Mark P M Harms
- Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Ciáran Finucane
- Department of Medical Physics & Bioengineering, Mercer's Institute for Successful Ageing, St James's Hospital, Dublin 8, Ireland; Department of Medical Gerontology, School of Medicine, Trinity College Dublin, Ireland
| | - Laura Pérez-Denia
- Department of Medical Physics & Bioengineering, Mercer's Institute for Successful Ageing, St James's Hospital, Dublin 8, Ireland; Department of Medical Gerontology, School of Medicine, Trinity College Dublin, Ireland
| | - Stephen P Juraschek
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Veera K van Wijnen
- Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Lewis A Lipsitz
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA; Hinda and Arthur Marcus Institute for Aging Research, Hebrew Senior Life, Boston, MA, USA
| | - Johannes J van Lieshout
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; School of Life Sciences, The Medical School, MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, Queen's Medical Centre, Nottingham, United Kingdom
| | - Wouter Wieling
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.
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Kim YS, van der Ster BJP, Brassard P, Secher NH, van Lieshout JJ. Cerebral vs. Cardiovascular Responses to Exercise in Type 2 Diabetic Patients. Front Physiol 2021; 11:583155. [PMID: 33519500 PMCID: PMC7844205 DOI: 10.3389/fphys.2020.583155] [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: 07/14/2020] [Accepted: 12/23/2020] [Indexed: 12/17/2022] Open
Abstract
The human brain is constantly active and even small limitations to cerebral blood flow (CBF) may be critical for preserving oxygen and substrate supply, e.g., during exercise and hypoxia. Exhaustive exercise evokes a competition for the supply of oxygenated blood between the brain and the working muscles, and inability to increase cardiac output sufficiently during exercise may jeopardize cerebral perfusion of relevance for diabetic patients. The challenge in diabetes care is to optimize metabolic control to slow progression of vascular disease, but likely because of a limited ability to increase cardiac output, these patients perceive aerobic exercise to be more strenuous than healthy subjects and that limits the possibility to apply physical activity as a preventive lifestyle intervention. In this review, we consider the effects of functional activation by exercise on the brain and how it contributes to understanding the control of CBF with the limited exercise tolerance experienced by type 2 diabetic patients. Whether a decline in cerebral oxygenation and thereby reduced neural drive to working muscles plays a role for "central" fatigue during exhaustive exercise is addressed in relation to brain's attenuated vascular response to exercise in type 2 diabetic subjects.
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Affiliation(s)
- Yu-Sok Kim
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Internal Medicine, Medisch Centrum Leeuwarden, Leeuwarden, Netherlands
| | - Björn J. P. van der Ster
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Anesthesiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Niels H. Secher
- Department of Anesthesia, The Copenhagen Muscle Research Center, University of Copenhagen, Copenhagen, Denmark
| | - Johannes J. van Lieshout
- Laboratory for Clinical Cardiovascular Physiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
- MRC/Arthritis Research UK Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen’s Medical Centre, Nottingham, United Kingdom
- Department of Internal Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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11
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Zohdi H, Scholkmann F, Wolf U. Individual Differences in Hemodynamic Responses Measured on the Head Due to a Long-Term Stimulation Involving Colored Light Exposure and a Cognitive Task: A SPA-fNIRS Study. Brain Sci 2021; 11:54. [PMID: 33466405 PMCID: PMC7824905 DOI: 10.3390/brainsci11010054] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/20/2020] [Accepted: 12/30/2020] [Indexed: 12/11/2022] Open
Abstract
When brain activity is measured by neuroimaging, the canonical hemodynamic response (increase in oxygenated hemoglobin ([O2Hb]) and decrease in deoxygenated hemoglobin ([HHb]) is not always seen in every subject. The reason for this intersubject-variability of the responses is still not completely understood. This study is performed with 32 healthy subjects, using the systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS) approach. We investigate the intersubject variability of hemodynamic and systemic physiological responses, due to a verbal fluency task (VFT) under colored light exposure (CLE; blue and red). Five and seven different hemodynamic response patterns were detected in the subgroup analysis of the blue and red light exposure, respectively. We also found that arterial oxygen saturation and mean arterial pressure were positively correlated with [O2Hb] at the prefrontal cortex during the CLE-VFT independent of the color of light and classification of the subjects. Our study finds that there is substantial intersubject-variability of cerebral hemodynamic responses, which is partially explained by subject-specific systemic physiological changes induced by the CLE-VFT. This means that both subgroup analyses and the additional assessment of systemic physiology are of crucial importance to achieve a comprehensive understanding of the effects of a CLE-VFT on human subjects.
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Affiliation(s)
- Hamoon Zohdi
- Institute of Complementary and Integrative Medicine, University of Bern, 3012 Bern, Switzerland; (H.Z.); (F.S.)
| | - Felix Scholkmann
- Institute of Complementary and Integrative Medicine, University of Bern, 3012 Bern, Switzerland; (H.Z.); (F.S.)
- Biomedical Optics Research Laboratory, Neonatology Research, Department of Neonatology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland
| | - Ursula Wolf
- Institute of Complementary and Integrative Medicine, University of Bern, 3012 Bern, Switzerland; (H.Z.); (F.S.)
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12
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Bellissimo G, Leslie E, Maestas V, Zuhl M. The Effects of Fast and Slow Yoga Breathing on Cerebral and Central Hemodynamics. Int J Yoga 2020; 13:207-212. [PMID: 33343150 PMCID: PMC7735505 DOI: 10.4103/ijoy.ijoy_98_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 02/26/2020] [Accepted: 04/08/2020] [Indexed: 12/17/2022] Open
Abstract
Background: Yoga breathing has shown to impose significant cardiovascular and psychological health benefits. Objective: The mechanism (s) responsible for these health benefits remain unclear. The aim of the present study was to assess the differences in cerebral and central hemodynamic responses following fast breathing (FB) and slow breathing (SB) protocols compared to breathing awareness (BA) as a control. Methods: Twenty healthy participants (10 males and 10 females) volunteered to take part in the study. Participants were between ages 18–55 years (group mean: 24 ± 5 years), with a height of 168.7 ± 9.8 cm and a weight of 70.16 ± 10.9 kg. A familiarization trial including FB and SB protocols were performed by each participant at least 24 h before the testing day. The breathing protocols were designed to achieve 6 breath/min for SB and ~ 120 breaths/min for FB. Results: FB resulted in an increase in both right prefrontal cortex (RPFC) and left prefrontal cortex (LPFC) hemoglobin difference (Hbdiff) (brain oxygenation) compared to BA (P < 0.05). FB resulted in an increased Hbdiff in LPFC compared to RPFC SB (P < 0.05). FB resulted in an increased Hbdiff in LPFC compared to SB (P < 0.05). Conclusion: FB may be an effective yoga breathing technique for eliciting cerebral brain oxygenation indicated by increased Hbdiff. These results may be applicable to both healthy and clinical populations.
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Affiliation(s)
- Gabriella Bellissimo
- Department of Health, Exercise, and Sports Sciences, University of New Mexico, Albuquerque, NM, USA
| | - Eric Leslie
- Department of Health, Exercise, and Sports Sciences, University of New Mexico, Albuquerque, NM, USA
| | - Valarie Maestas
- Department of Health, Exercise, and Sports Sciences, University of New Mexico, Albuquerque, NM, USA
| | - Micah Zuhl
- Department of Health, Exercise, and Sports Sciences, University of New Mexico, Albuquerque, NM, USA.,School of Health Sciences, Central Michigan University, Mt. Pleasant, MI, USA
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13
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Sørensen H. Is cerebral monitoring useful? Focus must shift from mere observation to testing interventions. Acta Anaesthesiol Scand 2020; 64:568-569. [PMID: 32058601 DOI: 10.1111/aas.13562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 01/11/2020] [Accepted: 02/11/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Henrik Sørensen
- Department of Anaesthesia, Centre for Cancer and Organ Diseases, Copenhagen, Denmark.,Department of Integrative Physiology, NEXS, University of Copenhagen, Copenhagen, Denmark
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14
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Kim JB, Phillips Z, Paik SH, Kang SY, Jeon NJ, Kim BJ, Kim BM. Cerebral hemodynamic monitoring of Parkinson's disease patients with orthostatic intolerance during head-up tilt test. NEUROPHOTONICS 2020; 7:025002. [PMID: 32411811 PMCID: PMC7202364 DOI: 10.1117/1.nph.7.2.025002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
Significance: Monitoring of cerebral perfusion rather than blood pressure changes during a head-up tilt test (HUTT) is proposed to understand the pathophysiological effect of orthostatic intolerance (OI), including orthostatic hypotension (OH), in Parkinson's disease (PD) patients. Aim: We aim to characterize and distinguish the cerebral perfusion response to a HUTT for healthy controls (HCs) and PD patients with OI symptoms. Approach: Thirty-nine PD patients with OI symptoms [10 PD patients with OH (PD-OH) and 29 PD patients with normal HUTT results (PD-NOR)], along with seven HCs participated. A 108-channel diffuse optical tomography (DOT) system was used to reconstruct prefrontal oxyhemoglobin (HbO), deoxyhemoglobin (Hb), and total hemoglobin (HbT) changes during dynamic tilt (from supine to 70-deg tilt) and static tilt (remained tilted at 70 deg). Results: HCs showed rapid recovery of cerebral perfusion in the early stages of static tilt. PD-OH patients showed decreasing HbO and HbT during dynamic tilt, continuing into the static tilt period. The rate of HbO change from dynamic tilt to static tilt is the distinguishing feature between HCs and PD-OH patients. Accordingly, PD-NOR patients were subgrouped based on positive-rate and negative-rate of HbO change. PD patients with a negative rate of HbO change were more likely to report severe OI symptoms in the COMPASS questionnaire. Conclusions: Our findings showcase the usability of DOT for sensitive detection and quantification of autonomic dysfunction in PD patients with OI symptoms, even those with normal HUTT results.
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Affiliation(s)
- Jung Bin Kim
- Korea University Anam Hospital, Department of Neurology, Seoul, Republic of Korea
| | - Zephaniah Phillips
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
| | - Seung-ho Paik
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
- KLIEN Inc., Seoul Biohub, Seoul, Republic of Korea
| | - Shin-young Kang
- Korea University, Department of Bio-Convergence Engineering, Seoul, Republic of Korea
| | - Nam-Joon Jeon
- Korea University Anam Hospital, Neurophysiology Laboratory, Seoul, Republic of Korea
| | - Byung-Jo Kim
- Korea University Anam Hospital, Department of Neurology, Seoul, Republic of Korea
- Korea University Anam Hospital, Brain Convergence Research Center, Seoul, Republic of Korea
| | - Beop-Min Kim
- Korea University Anam Hospital, Department of Neurology, Seoul, Republic of Korea
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15
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Smarius BJA, Breugem CC, Boasson MP, Alikhil S, van Norden J, van der Molen ABM, de Graaff JC. Effect of hyperextension of the neck (rose position) on cerebral blood oxygenation in patients who underwent cleft palate reconstructive surgery: prospective cohort study using near-infrared spectroscopy. Clin Oral Investig 2020; 24:2909-2918. [PMID: 32219565 DOI: 10.1007/s00784-019-03157-8] [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: 03/26/2019] [Accepted: 11/13/2019] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To facilitate the best approach during cleft palate surgery, children are positioned with hyperextension of the neck. Extensive head extension may induce intraoperative cerebral ischemia if collateral flow is insufficient. To evaluate and monitor the effect of cerebral blood flow on cerebral tissue oxygenation, near-infrared spectroscopy has proved to be a valuable method. The aim of this study was to evaluate and quantify whether hyperextension affects the cerebral tissue oxygenation in children during cleft palate surgery. MATERIALS AND METHODS This prospective study included children (ASA 1 and 2) under the age of 3 years old who underwent cleft palate repair at the Wilhelmina Children's Hospital, in The Netherlands. Data were collected for date of birth, cleft type, date of cleft repair, and physiological parameters (MAP, saturation, heart rate, expiratory CO2 and O2, temperature, and cerebral blood oxygenation) during surgery. The cerebral blood oxygenation was measured with NIRS. RESULTS Thirty-four children were included in this study. The majority of the population was male (61.8%, n = 21). The mixed model analyses showed a significant drop at time of Rose position of - 4.25 (69-74 95% CI; p < 0.001) and - 4.39 (69-74 95% CI; p < 0.001). Postoperatively, none of the children displayed any neurological disturbance. CONCLUSION This study suggests that hyperextension of the head during cleft palate surgery leads to a significant decrease in cerebral oxygenation. Severe cerebral desaturation events during surgery were uncommon and do not seem to be of clinical relevance in ASA 1 and 2 children. CLINICAL RELEVANCE There was a significant drop in cerebral oxygenation after positioning however it is not clear whether this drop is truly significant physiologically in ASA 1 and 2 patients.
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Affiliation(s)
- B J A Smarius
- Department of Pediatric Plastic Surgery, Wilhelmina Children's Hospital, University Medical Center Utrecht, P.O. 85090, 3508 AB, Utrecht, The Netherlands.
| | - C C Breugem
- Department of Pediatric Plastic Surgery, Emma Children's Hospital, University Medical Center Amsterdam, Amsterdam, The Netherlands.,Department of Plastic Surgery, Meander Medical Center, Amersfoort, The Netherlands
| | - M P Boasson
- Department of Anesthesia, University Medical Center Utrecht, Utrecht, The Netherlands
| | - S Alikhil
- Department of Anesthesia, University Medical Center Utrecht, Utrecht, The Netherlands
| | - J van Norden
- Department of Anesthesia, University Medical Center Utrecht, Utrecht, The Netherlands
| | - A B Mink van der Molen
- Department of Pediatric Plastic Surgery, Wilhelmina Children's Hospital, University Medical Center Utrecht, P.O. 85090, 3508 AB, Utrecht, The Netherlands
| | - J C de Graaff
- Department of Anesthesia, University Medical Center Utrecht, Utrecht, The Netherlands. .,Department of Anesthesia, Erasmus MC Sophia Children's Hospital, Rotterdam, The Netherlands.
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16
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Gibbons TD, Zuj KA, Prince CN, Kingston DC, Peterson SD, Hughson RL. Haemodynamic and cerebrovascular effects of intermittent lower-leg compression as countermeasure to orthostatic stress. Exp Physiol 2019; 104:1790-1800. [PMID: 31578774 DOI: 10.1113/ep088077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 09/30/2019] [Indexed: 02/04/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does smartly timed intermittent compression of the lower legs alter cerebral blood velocity and oxygenation during acute orthostatic challenges? What is the main finding and its importance? Intermittent compression timed to the local diastolic phase increased the blood flux through the legs and heart after two different orthostatic stress tests. Cerebral blood velocity improved during the first minute of recovery, and indices of cerebral tissue oxygenation remained elevated for 2 min. These results provide promise for the use of lower-leg active compression as a therapeutic tool for individuals vulnerable to initial orthostatic hypotension and orthostatic stress. ABSTRACT Intermittent compression of the lower legs provides the possibility of improving orthostatic tolerance by actively promoting venous return and improving central haemodynamics. We tested the hypothesis that intermittent compression of 65 mmHg timed to occur only within the local diastolic phase of each cardiac cycle would attenuate the decrease in blood pressure and improve cerebral haemodynamics during the first minute of recovery from two different orthostatic stress tests. Fourteen subjects (seven female) performed four squat-to-stand transitions and four repeats of standing bilateral thigh-cuff occlusion and release (TCR), with intermittent compression of the lower legs applied in half of the trials. Blood flow in the superficial femoral artery, mean arterial pressure, Doppler ultrasound cardiac output, total peripheral resistance, middle cerebral artery blood velocity (MCAv) and cerebral tissue saturation index (TSI%) were monitored. With both orthostatic stress tests, there was a significant compression × time interaction for superficial femoral artery flow (P < 0.001). The hypotensive state was attenuated with intermittent compression despite decreased total peripheral resistance (squat-to-stand, compression × time interaction, P < 0.001; TCR, compression × time interaction, P = 0.002) as a consequence of elevated cardiac output in both tests (P < 0.001). Intermittent compression also increased MCAv (P = 0.001) and TSI% (P < 0.001) during the squat-to-stand transition and during TCR (MCAv and TSI%, compression × time interaction, P < 0.001). Intermittent compression of the lower legs during quiet standing after an active orthostatic challenge augmented local, central and cerebral haemodynamics, providing potential as a therapeutic tool for individuals vulnerable to orthostatic stress.
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Affiliation(s)
- Travis D Gibbons
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Kathryn A Zuj
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Chekema N Prince
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, Canada
| | - David C Kingston
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Sean D Peterson
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, Canada
| | - Richard L Hughson
- Schlegel-University of Waterloo Research Institute for Aging, Faculty of Applied Health Sciences, Waterloo, ON, Canada
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17
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Gibbons TD, Zuj KA, Peterson SD, Hughson RL. Comparison of pulse contour, aortic Doppler ultrasound and bioelectrical impedance estimates of stroke volume during rapid changes in blood pressure. Exp Physiol 2019; 104:368-378. [PMID: 30582758 DOI: 10.1113/ep087240] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/18/2018] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Pulse contour analysis of the finger arterial pressure by Windkessel modelling is commonly used to estimate stroke volume continuously. But is it valid during dynamic changes in blood pressure? What is the main finding and its importance? Second-by-second analysis revealed that pulse contour analysis underestimated stroke volume by up to 25% after standing from a squat, and 16% after standing thigh-cuff release, when compared with aortic Doppler ultrasound estimates. These results reveal that pulse contour analysis of stroke volume should be interpreted with caution during rapid changes in physiological state. ABSTRACT Dynamic measurements of stroke volume (SV) and cardiac output provide an index of central haemodynamics during transitional states, such as postural changes and onset of exercise. The most widely used method to assess dynamic fluctuations in SV is the Modelflow method, which uses the arterial blood pressure waveform along with age- and sex-specific aortic properties to compute beat-to-beat estimates of aortic flow. Modelflow has been validated against more direct methods in steady-state conditions, but not during dynamic changes in physiological state, such as active orthostatic stress testing. In the present study, we compared the dynamic SV responses from Modelflow (SVMF ), aortic Doppler ultrasound (SVU/S ) and bioelectrical impedance analysis (SVBIA ) during two different orthostatic stress tests, a squat-to-stand (S-S) transition and a standing bilateral thigh-cuff release (TCR), in 15 adults (six females). Second-by-second analysis revealed that when compared with estimates of SV by aortic Doppler ultrasound, Modelflow underestimated SV by up to 25% from 3 to 11 s after standing from the squat position and by up to 16% from 3 to 7 s after TCR (P < 0.05). The SVMF and SVBIA were similar during the first minute of the S-S transition, but were different 3 s after TCR and at intermittent time points between 34 and 44 s (P < 0.05). These findings indicate that the physiological conditions elicited by orthostatic stress testing violate some of the inherent assumptions of Modelflow and challenge models used to interpret bioelectrical impedance responses, resulting in an underestimation in SV during rapid changes in physiological state.
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Affiliation(s)
- Travis D Gibbons
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Kathryn A Zuj
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada
| | - Sean D Peterson
- Department of Mechanical and Mechatronic Engineering, University of Waterloo, Waterloo, ON, Canada
| | - Richard L Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON, Canada.,Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON, Canada
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18
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Konda PR, Sharma PK, Gandhi AR, Ganguly E. Correlates of Cognitive Impairment among Indian Urban Elders. JOURNAL OF GERONTOLOGY & GERIATRIC RESEARCH 2018; 7:489. [PMID: 31406631 PMCID: PMC6690611 DOI: 10.4172/2167-7182.1000489] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Cognitive impairment among elderly is increasing owing to increases in life expectancy globally. The problem is multifactorial. The objective of the present paper was to study the correlates of cognitive impairment in an urban elderly population in India. METHODS A cross sectional study was conducted among 100 randomly selected urban elderly population. Data was collected upon household visits using a predesigned pretested questionnaire administered by a trained investigator. Measurements included cognitive function assessment using Mini Mental State Examination, depression assessment using Geriatric Depression Scale, blood pressure measurement and anthropometry. Cognitive impairment was defined at MMSE score <24. Logistic regression was done to identify independently associated factors with cognitive impairment. RESULTS Prevalence of cognitive impairment among elderly was 10%. Women had a higher prevalence than men. Higher age, no schooling, living single, lower weight, lower waist and hip ratios, difficulty in activities of daily living, poor self-reported health, bedridden and depression significantly associated with cognitive impairment. The independently associated factors upon logistic regression were increasing age, no schooling and bedridden status for past six months. CONCLUSION Although the current prevalence of cognitive impairment among Indian urban elderly is low, several associated factors exist in this population that may increase the burden in future. Geriatric health policy should address the modifiable risk factors to manage the problem of cognitive impairment and its consequent outcomes.
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Affiliation(s)
| | - Pawan Kumar Sharma
- Department of Community Medicine, Mediciti Institute of Medical Sciences, Ghanpur, Hyderabad, India
- Department of Epidemiology, University of Pittsburgh, and Share India, Fogarty International NIH, USA
| | - Atul R Gandhi
- Consultant Statistician & Chief Manager-Monitoring and Evaluation, EdelGive Foundation, Edelweiss House, Mumbai, India
| | - Enakshi Ganguly
- Department of Community Medicine, Mediciti Institute of Medical Sciences, Ghanpur, Hyderabad, India
- Department of Epidemiology, University of Pittsburgh, and Share India, Fogarty International NIH, USA
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19
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20
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Curtelin D, Morales-Alamo D, Torres-Peralta R, Rasmussen P, Martin-Rincon M, Perez-Valera M, Siebenmann C, Pérez-Suárez I, Cherouveim E, Sheel AW, Lundby C, Calbet JA. Cerebral blood flow, frontal lobe oxygenation and intra-arterial blood pressure during sprint exercise in normoxia and severe acute hypoxia in humans. J Cereb Blood Flow Metab 2018; 38:136-150. [PMID: 28186430 PMCID: PMC5757439 DOI: 10.1177/0271678x17691986] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cerebral blood flow (CBF) is regulated to secure brain O2 delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O2 delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (PIO2 = 73 mmHg). During the sprints, cardiac output increased to ∼22 L min-1, mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7.5 s and decreased to pre-exercise values towards the end of the sprint. When the sprints in normoxia were preceded by a reduced PETCO2, CBF and frontal lobe oxygenation decreased in parallel ( r = 0.93, P < 0.01). In hypoxia, MCAv was increased by 25%, due to a 26% greater vascular conductance, despite 4-6 mmHg lower PaCO2 in hypoxia than normoxia. This vasodilation fully accounted for the 22 % lower CaO2 in hypoxia, leading to a similar brain O2 delivery during the sprints regardless of PIO2. In conclusion, when a conflict exists between preserving brain O2 delivery or restraining CBF to avoid potential damage by an elevated perfusion pressure, the priority is given to brain O2 delivery.
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Affiliation(s)
- David Curtelin
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,2 Emergency Medicine Department, Insular Universitary Hospital of Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - David Morales-Alamo
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Rafael Torres-Peralta
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Peter Rasmussen
- 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Marcos Martin-Rincon
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Mario Perez-Valera
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Christoph Siebenmann
- 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - Ismael Pérez-Suárez
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
| | - Evgenia Cherouveim
- 5 Department of Physical Education and Sport Sciences, National and Kapodistrian University of Athens, Athens, Greece
| | - A William Sheel
- 6 School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Carsten Lundby
- 4 Center for Integrative Human Physiology, Institute of Physiology, University of Zürich, Zürich, Switzerland
| | - José Al Calbet
- 1 Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,3 Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
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21
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van Wijnen VK, Finucane C, Harms MPM, Nolan H, Freeman RL, Westerhof BE, Kenny RA, Ter Maaten JC, Wieling W. Noninvasive beat-to-beat finger arterial pressure monitoring during orthostasis: a comprehensive review of normal and abnormal responses at different ages. J Intern Med 2017; 282:468-483. [PMID: 28564488 DOI: 10.1111/joim.12636] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Over the past 30 years, noninvasive beat-to-beat blood pressure (BP) monitoring has provided great insight into cardiovascular autonomic regulation during standing. Although traditional sphygmomanometric measurement of BP may be sufficient for detection of sustained orthostatic hypotension, it fails to capture the complexity of the underlying dynamic BP and heart rate responses. With the emerging use of noninvasive beat-to-beat BP monitoring for the assessment of orthostatic BP control in clinical and population studies, various definitions for abnormal orthostatic BP patterns have been used. Here, age-related changes in cardiovascular control in healthy subjects will be reviewed to define the spectrum of the most important abnormal orthostatic BP patterns within the first 180 s of standing. Abnormal orthostatic BP responses can be defined as initial orthostatic hypotension (a transient systolic BP fall of >40 mmHg within 15 s of standing), delayed BP recovery (an inability of systolic BP to recover to a value of >20 mmHg below baseline at 30 s after standing) and sustained orthostatic hypotension (a sustained decline in systolic BP of ≥20 mmHg occurring 60-180 s after standing). In the evaluation of patients with light-headedness, pre(syncope), (unexplained) falls or suspected autonomic dysfunction, it is essential to distinguish between normal cardiovascular autonomic regulation and these abnormal orthostatic BP responses. The prevalence, clinical relevance and underlying pathophysiological mechanisms of these patterns differ significantly across the lifespan. Initial orthostatic hypotension is important for identifying causes of syncope in younger adults, whereas delayed BP recovery and sustained orthostatic hypotension are essential for evaluating the risk of falls in older adults.
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Affiliation(s)
- V K van Wijnen
- Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - C Finucane
- Department of Medical Physics, Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
| | - M P M Harms
- Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - H Nolan
- Department of Medical Gerontology, The Irish Longitudinal Study on Ageing (TILDA), Lincoln Gate, Trinity College, Dublin, Ireland
| | - R L Freeman
- Neurology Department, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - B E Westerhof
- Department of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands.,Heart Failure Research Center, Laboratory for Clinical Cardiovascular Physiology, Academic Medical Center, Amsterdam, The Netherlands
| | - R A Kenny
- Department of Medical Gerontology, The Irish Longitudinal Study on Ageing (TILDA), Lincoln Gate, Trinity College, Dublin, Ireland.,Mercer's Institute for Successful Ageing, St James's Hospital, Dublin, Ireland
| | - J C Ter Maaten
- Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - W Wieling
- Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands
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22
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Távora-Mehta MZP, Mehta N, Magajevski A, Oliveira LD, Maluf DLS, Concato L, Doubrawa E, Ortiz MR, Cunha CLPD. Reduced Systolic Volume: Main Pathophysiological Mechanism in Patients with Orthostatic Intolerance? Arq Bras Cardiol 2017; 107:354-364. [PMID: 27849259 PMCID: PMC5102482 DOI: 10.5935/abc.20160135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/08/2016] [Indexed: 11/20/2022] Open
Abstract
Background Orthostatic intolerance patients' pathophysiological mechanism is still
obscure, contributing to the difficulty in their clinical management. Objective To investigate hemodynamic changes during tilt test in individuals with
orthostatic intolerance symptoms, including syncope or near syncope. Methods Sixty-one patients who underwent tilt test at - 70° in the phase without
vasodilators were divided into two groups. For data analysis, only the first
20 minutes of tilting were considered. Group I was made up of 33 patients
who had an increase of total peripheral vascular resistance (TPVR) during
orthostatic position; and Group II was made up of 28 patients with a
decrease in TPVR (characterizing insufficient peripheral vascular
resistance). The control group consisted of 24 healthy asymptomatic
individuals. Hemodynamic parameters were obtained by a non-invasive
hemodynamic monitor in three different moments (supine position, tilt 10'
and tilt 20') adjusted for age. Results In the supine position, systolic volume (SV) was significantly reduced in
both Group II and I in comparison to the control group, respectively (66.4
±14.9 ml vs. 81.8±14.8 ml vs. 101.5±24.2 ml;
p<0.05). TPVR, however, was higher in Group II in comparison to Group I
and controls, respectively (1750.5± 442 dyne.s/cm5
vs.1424±404 dyne.s/cm5 vs. 974.4±230
dyne.s/cm5; p<0.05). In the orthostatic position, at 10',
there was repetition of findings, with lower absolute values of SV compared
to controls (64.1±14.0 ml vs 65.5±11.3 ml vs 82.8±15.6
ml; p<0.05). TPVR, on the other hand, showed a relative drop in Group II,
in comparison to Group I. Conclusion Reduced SV was consistently observed in the groups of patients with
orthostatic intolerance in comparison to the control group. Two different
responses to tilt test were observed: one group with elevated TPVR and
another with a relative drop in TPVR, possibly suggesting a more severe
failure of compensation mechanisms.
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Affiliation(s)
| | - Niraj Mehta
- Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Adriano Magajevski
- Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | | | | | - Letícia Concato
- Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
| | - Eduardo Doubrawa
- Hospital de Clínicas, Universidade Federal do Paraná, Curitiba, PR, Brazil
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23
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Imhoff S, Malenfant S, Nadreau É, Poirier P, Bailey DM, Brassard P. Uncoupling between cerebral perfusion and oxygenation during incremental exercise in an athlete with postconcussion syndrome: a case report. Physiol Rep 2017; 5:5/2/e13131. [PMID: 28122826 PMCID: PMC5269417 DOI: 10.14814/phy2.13131] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 12/21/2016] [Accepted: 12/23/2016] [Indexed: 11/24/2022] Open
Abstract
High-intensity exercise may pose a risk to patients with postconcussion syndrome (PCS) when symptomatic during exertion. The case of a paralympic athlete with PCS who experienced a succession of convulsion-awakening periods and reported a marked increase in postconcussion symptoms after undergoing a graded symptom-limited aerobic exercise protocol is presented. Potential mechanisms of cerebrovascular function failure are then discussed.
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Affiliation(s)
- Sarah Imhoff
- Department of Kinesiology, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada.,Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
| | - Simon Malenfant
- Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada.,Pulmonary Hypertension Research Group, Quebec Heart and Lungs Institute Research Center, Laval University, Quebec City, Quebec, Canada
| | - Éric Nadreau
- Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
| | - Paul Poirier
- Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, South Wales, United Kingdom.,Sondes Moléculaires en Biologie, Laboratoire Chimie Provence UMR 6264 CNRS, Université de Provence Marseille, Marseille, France
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada .,Research Center of the Institut universitaire de cardiologie et de pneumologie de Québec, Laval University, Quebec City, Quebec, Canada
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24
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Bronzwaer ASGT, Verbree J, Stok WJ, Daemen MJAP, van Buchem MA, van Osch MJP, van Lieshout JJ. The cerebrovascular response to lower-body negative pressure vs. head-up tilt. J Appl Physiol (1985) 2017; 122:877-883. [PMID: 28082333 DOI: 10.1152/japplphysiol.00797.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 11/22/2022] Open
Abstract
Lower-body negative pressure (LBNP) has been proposed as a MRI-compatible surrogate for orthostatic stress. Although the effects of LBNP on cerebral hemodynamic behavior have been considered to reflect those of orthostatic stress, a direct comparison with actual orthostasis is lacking. We assessed the effects of LBNP (-50 mmHg) vs. head-up tilt (HUT; at 70°) in 10 healthy subjects (5 female) on transcranial Doppler-determined cerebral blood flow velocity (CBFv) in the middle cerebral artery and cerebral perfusion pressure (CPP) as estimated from the blood pressure signal (finger plethysmography). CPP was maintained during LBNP but decreased after 2 min in response to HUT, leading to an ~15% difference in CPP between LBNP and HUT (P ≤ 0.020). Mean CBFv initially decreased similarly in response to LBNP and for HUT, but, from minute 3 on, the decline became ~50% smaller (P ≤ 0.029) during LBNP. The reduction in end-tidal Pco2 partial pressure (PetCO2 ) was comparable but with an earlier return toward baseline values in response to LBNP but not during HUT (P = 0.008). We consider the larger decrease in CBFv during HUT vs. LBNP attributable to the pronounced reduction in PetCO2 and to gravitational influences on CPP, and this should be taken into account when applying LBNP as an MRI-compatible orthostatic stress modality.NEW & NOTEWORTHY Lower-body negative pressure (LBNP) has the potential to serve as a MRI-compatible surrogate of orthostatic stress but a comparison with actual orthostasis was lacking. This study showed that the pronounced reduction in end-tidal Pco2 together with gravitational effects on the brain circulation lead to a larger decline in cerebral blood flow velocity in response to head-up tilt than during lower-body negative pressure. This should be taken into account when employing lower-body negative pressure as MRI-compatible alternative to orthostatic stress.
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Affiliation(s)
- Anne-Sophie G T Bronzwaer
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Jasper Verbree
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Wim J Stok
- Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Mat J A P Daemen
- Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; and
| | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Johannes J van Lieshout
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; .,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Medical Research Center/Arthritis Research United Kingdom Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, United Kingdom
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25
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Guo H, Schaller F, Tierney N, Smith SA, Shi X. New Insight into the Mechanism of Cardiovascular Dysfunction in the Elderly: Transfer Function Analysis. Exp Biol Med (Maywood) 2016; 230:549-57. [PMID: 16118405 DOI: 10.1177/153537020523000806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
This study sought to test the hypothesis that alterations in the relationships between (i) mean arterial pressure (MAP) and heart rate (HR), (ii) cardiac output (CO) and MAP, and (Hi) total Peripheral resistance (TPR) and MAP variability contribute to the diminished dynamic control of cardiovascular function with advanced age. Six-minute hemodynamic data were continuously recorded in 11 elderly (70 ± 2 years) and 11 young (26 ± 1 year) healthy volunteers under supine resting condition and during lower body negative pressure–induced orthostatic challenge. The data were converted using fast Fourier transform, and the ratio of cross-spectra to auto-spectra between two signals (i.e., MAP-HR, CO-MAP, TPR-MAP) was computed for transfer function analysis. In the low-frequency ranges (LF; 0.04–O.14 Hz) and high-frequency ranges (0.15–0.30 Hz), the gain and coherence of the transfer function describing the relationship between MAP-HR signals were significantly greater in younger than in older adults. The phase degree was significantly >0 in both groups under all conditions, suggesting that the MAP variability preceded the HR variability. In contrast, the coherence between CO-MAP signals in both age groups was <0.5, indicating that the beat-to-beat MAP variability was not significantly related to the CO signals. However, the transfer function gain and coherence of TPR-MAP signals were significantly greater in the young group (coherence ≥0.5 in the LF range), suggesting a more effective dynamic vasomotor control. In conclusion, the oscillations in CO-MAP signals are not significantly synchronized or not related in a simply linear fashion in both age groups. The MAP variability is more related to the oscillation of TPR signals in the young group only. Advanced age not only diminishes MAP-HR transfer function gain, but also weakens its coherence. Thus, alterations in the relationship between MAP-HR variability and TPR-MAP variability may significantly contribute to the diminished dynamic control of cardiovascular function manifest in the elderly.
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Affiliation(s)
- Hong Guo
- Department of Integrative Physiology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
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26
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Gutkin M, Stewart JM. Orthostatic Circulatory Disorders: From Nosology to Nuts and Bolts. Am J Hypertens 2016; 29:1009-19. [PMID: 27037712 PMCID: PMC4978226 DOI: 10.1093/ajh/hpw023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Revised: 11/27/2015] [Accepted: 02/12/2016] [Indexed: 12/17/2022] Open
Abstract
When patients complain of altered consciousness or discomfort in the upright posture, either relieved by recumbency or culminating in syncope, physicians may find themselves baffled. There is a wide variety of disorders that cause abnormal regulation of blood pressure and pulse rate in the upright posture. The aim of this focused review is 3-fold. First, to offer a classification (nosology) of these disorders; second, to illuminate the mechanisms that underlie them; and third, to assist the physician in the practical aspects of diagnosis of adult orthostatic hypotension, by extending clinical skills with readily available office technology.
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Affiliation(s)
- Michael Gutkin
- Hypertension Section, Saint Barnabas Medical Center, Livingston, New Jersey, USA;
| | - Julian M Stewart
- Center for Hypotension, New York Medical College, Valhalla, New Jersey, USA
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27
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Kay VL, Rickards CA. The role of cerebral oxygenation and regional cerebral blood flow on tolerance to central hypovolemia. Am J Physiol Regul Integr Comp Physiol 2016; 310:R375-83. [DOI: 10.1152/ajpregu.00367.2015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 12/14/2015] [Indexed: 11/22/2022]
Abstract
Tolerance to central hypovolemia is highly variable, and accumulating evidence suggests that protection of anterior cerebral blood flow (CBF) is not an underlying mechanism. We hypothesized that individuals with high tolerance to central hypovolemia would exhibit protection of cerebral oxygenation (ScO2), and prolonged preservation of CBF in the posterior vs. anterior cerebral circulation. Eighteen subjects (7 male/11 female) completed a presyncope-limited lower body negative pressure (LBNP) protocol (3 mmHg/min onset rate). ScO2 (via near-infrared spectroscopy), middle cerebral artery velocity (MCAv), posterior cerebral artery velocity (PCAv) (both via transcranial Doppler ultrasound), and arterial pressure (via finger photoplethysmography) were measured continuously. Subjects who completed ≥70 mmHg LBNP were classified as high tolerant (HT; n = 7) and low tolerant (LT; n = 11) if they completed ≤60 mmHg LBNP. The minimum difference in LBNP tolerance between groups was 193 s (LT = 1,243 ± 185 s vs. HT = 1,996 ± 212 s; P < 0.001; Cohen's d = 3.8). Despite similar reductions in mean MCAv in both groups, ScO2 decreased in LT subjects from −15 mmHg LBNP ( P = 0.002; Cohen's d=1.8), but was maintained at baseline values until −75 mmHg LBNP in HT subjects ( P < 0.001; Cohen's d = 2.2); ScO2 was lower at −30 and −45 mmHg LBNP in LT subjects ( P ≤ 0.02; Cohen's d ≥ 1.1). Similarly, mean PCAv decreased below baseline from −30 mmHg LBNP in LT subjects ( P = 0.004; Cohen's d = 1.0), but remained unchanged from baseline in HT subjects until −75 mmHg ( P = 0.006; Cohen's d = 2.0); PCAv was lower at −30 and −45 mmHg LBNP in LT subjects ( P ≤ 0.01; Cohen's d ≥ 0.94). Individuals with higher tolerance to central hypovolemia exhibit prolonged preservation of CBF in the posterior cerebral circulation and sustained cerebral tissue oxygenation, both associated with a delay in the onset of presyncope.
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Affiliation(s)
- Victoria L. Kay
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Caroline A. Rickards
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
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28
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Greaney JL, Kenney WL, Alexander LM. Sympathetic regulation during thermal stress in human aging and disease. Auton Neurosci 2015; 196:81-90. [PMID: 26627337 DOI: 10.1016/j.autneu.2015.11.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 02/07/2023]
Abstract
Humans control their core temperature within a narrow range via precise adjustments of the autonomic nervous system. In response to changing core and/or skin temperature, several critical thermoregulatory reflex effector responses are initiated and include shivering, sweating, and changes in cutaneous blood flow. Cutaneous vasomotor adjustments, mediated by modulations in sympathetic nerve activity (SNA), aid in the maintenance of thermal homeostasis during cold and heat stress since (1) they serve as the first line of defense of body temperature and are initiated before other thermoregulatory effectors, and (2) they are on the efferent arm of non-thermoregulatory reflex systems, aiding in the maintenance of blood pressure and organ perfusion. This review article highlights the sympathetic responses of humans to thermal stress, with a specific focus on primary aging as well as impairments that occur in both heart disease and type 2 diabetes mellitus. Age- and pathology-related changes in efferent muscle and skin SNA during cold and heat stress, measured directly in humans using microneurography, are discussed.
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Affiliation(s)
- Jody L Greaney
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, PA 16802, United States.
| | - W Larry Kenney
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, PA 16802, United States
| | - Lacy M Alexander
- Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, PA 16802, United States
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29
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Jodaitis L, Vaillant F, Snacken M, Boland B, Spinewine A, Dalleur O, Gilles C, Petrovic M, Pepersack T. Orthostatic hypotension and associated conditions in geriatric inpatients. Acta Clin Belg 2015; 70:251-8. [PMID: 26135806 DOI: 10.1179/2295333715y.0000000006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Screening of orthostatic hypotension (OH) was performed in 285 patients aged 75 years. Current drugs, reasons for admission, geriatric syndromes, and confounding medical conditions were collected. Patients with OH (n = 116, 41%) as compared to those without OH (n = 169) more frequently (P < 0.01) presented falls in the last 6 months (62 vs. 40%, P < 0.001), a fall as the reason for the current admission (49 vs. 26%, P < 0.001), feeling of fainting (20 vs. 6%, P = 0.002), syncope (29 vs. 4%, P < 0.001) or functional decline (71 vs. 47%, P = 0.012). No difference was observed between the two groups in terms of age (85 ± 5 vs. 84 ± 4 years), gender (59 vs. 50% female), common geriatric conditions (e.g. malnutrition 46 vs. 58%, dementia 22 vs. 26%), comorbidity or confounding conditions (dehydration 28 vs. 30%, sepsis 2 vs. 6%). No difference was detected in the use of drugs with psychotropic cardiovascular or diuretic effect, or in their associations. Orthostatic hypotension is frequent upon hospital admission and should be screened, particularly in geriatric fallers. This absence of relation between OH and drugs use suggests that non-pharmacological interventions should be first attempted in older inpatients with OH before deciding to reduce or withdraw useful drugs.
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30
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Onizuka C, Niimi Y, Sato M, Sugenoya J. Arterial blood pressure response to head-up tilt test and orthostatic tolerance in nurses. Environ Health Prev Med 2015; 20:262-70. [PMID: 25894388 DOI: 10.1007/s12199-015-0455-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 03/02/2015] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES High tolerance to postural changes was examined in nurses. METHODS Twelve female nurses and 12 healthy controls underwent a 70° head-up tilt (HUT) test for 10 min. Blood pressure (BP), heart rate (HR), pulse pressure, and hormone levels were measured. Baroreceptor sensitivity (BRS) was calculated using a sequence technique. RESULTS HR increased during HUT in both subject groups, with no difference between groups. Systolic BP was rapidly increased by HUT in both subject groups, and was higher in the nurse group than in the control group during the first 2 min of HUT. Pulse pressure decreased during 1-2.5 min of HUT in the control group, but there was no decrease in the nurse group. BRS was decreased by HUT in the nurse group, while it tended to be decreased in the control group. Both during baseline and HUT, BRS was lower in the nurse group than in the control group. Plasma noradrenaline increased with HUT, and the increase was greater in the nurse group than in the control group. CONCLUSIONS Although nurse subjects had a lower BRS during HUT than control subjects, they were able to effectively maintain BP during HUT, suggesting that nurse subjects had higher orthostatic tolerance. The better maintenance of BP in nurse subjects appeared to be associated with a compensatory mechanism other than the arterial baroreflex and/or a hemodynamic mechanism.
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Affiliation(s)
- Chisato Onizuka
- Department of Physiology, Aichi Medical University, Nagakute, Aichi, 480-1195, Japan,
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31
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Nagaya S, Hayashi H, Fujimoto E, Maruoka N, Kobayashi H. Passive ankle movement increases cerebral blood oxygenation in the elderly: an experimental study. BMC Nurs 2015; 14:14. [PMID: 25838799 PMCID: PMC4383075 DOI: 10.1186/s12912-015-0066-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 03/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ankle exercise has been proven to be an effective intervention to increase venous velocity. However, the efficacy of ankle exercise for improving cerebral circulation has not been determined. We hypothesized that ankle exercise in the supine position would be able to increase oxyhemoglobin levels measured at the forehead. METHODS Seventeen community-dwelling elderly women participated in this study. We recorded blood pressure, heart rate (HR), and oxyhemoglobin (OxyHb) levels from the participants in the supine position. Participants repeated ankle plantar flexion and dorsiflexion movements for 1 min. Two types of exercise were used: active movement and passive movement. We used two-way analysis of variance to assess the differences in mean arterial blood pressure (MAP), HR, and OxyHb between different exercises (active and passive) and times (before and after exercise). RESULTS The HR and MAP increased during active exercise but not during passive exercise. On the other hand, the levels of OxyHb measured at the forehead were elevated during both active and passive exercises. This increase lasted at least 1 min after exercise. There was no significant difference between active and passive exercise with regard to OxyHb; however, a significant difference was observed between before and after exercise (p < 0.05, η(2) G = 0.153). CONCLUSIONS The physiological response of OxyHb to ankle exercise was different from that of the other cardiovascular functions. Both active and passive ankle exercises were able to increase cerebral blood oxygenation, whereas the other cardiovascular functions did not respond to passive exercise.
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Affiliation(s)
- Sachiko Nagaya
- Department of Nursing, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-minami, Higashi-ku, Nagoya City, Aichi 461-8673 Japan ; Department of Nursing, Ishikawa Prefectural Nursing University, 1-1 Gakuendai, Kahoku City, Ishikawa 929-1210 Japan
| | - Hisae Hayashi
- Department of Rehabilitation, Seijoh University, 2-172, Fukinodai, Tokai City, 476-8588 Japan
| | - Etsuko Fujimoto
- Department of Nursing, Nagoya University Graduate School of Medicine, 1-1-20 Daiko-minami, Higashi-ku, Nagoya City, Aichi 461-8673 Japan
| | - Naoko Maruoka
- Department of Nursing, Ishikawa Prefectural Nursing University, 1-1 Gakuendai, Kahoku City, Ishikawa 929-1210 Japan
| | - Hiromitsu Kobayashi
- Department of Nursing, Ishikawa Prefectural Nursing University, 1-1 Gakuendai, Kahoku City, Ishikawa 929-1210 Japan
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32
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Wieling W, van Dijk N, Thijs RD, de Lange FJ, Krediet CTP, Halliwill JR. Physical countermeasures to increase orthostatic tolerance. J Intern Med 2015; 277:69-82. [PMID: 24697914 DOI: 10.1111/joim.12249] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- W Wieling
- Department of Internal Medicine, Academic Medical Centre University of Amsterdam, Amsterdam, the Netherlands
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33
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Abstract
Evidence accumulated over 30 years, from experiments on animals and human subjects, has conclusively demonstrated that inputs from the vestibular otolith organs contribute to the control of blood pressure during movement and changes in posture. This review considers the effects of gravity on the body axis, and the consequences of postural changes on blood distribution in the body. It then separately considers findings collected in experiments on animals and human subjects demonstrating that the vestibular system regulates blood distribution in the body during movement. Vestibulosympathetic reflexes differ from responses triggered by unloading of cardiovascular receptors such as baroreceptors and cardiopulmonary receptors, as they can be elicited before a change in blood distribution occurs in the body. Dissimilarities in the expression of vestibulosympathetic reflexes in humans and animals are also described. In particular, there is evidence from experiments in animals, but not humans, that vestibulosympathetic reflexes are patterned, and differ between body regions. Results from neurophysiological and neuroanatomical studies in animals are discussed that identify the neurons that mediate vestibulosympathetic responses, which include cells in the caudal aspect of the vestibular nucleus complex, interneurons in the lateral medullary reticular formation, and bulbospinal neurons in the rostral ventrolateral medulla. Recent findings showing that cognition can modify the gain of vestibulosympathetic responses are also presented, and neural pathways that could mediate adaptive plasticity in the responses are proposed, including connections of the posterior cerebellar vermis with the vestibular nuclei and brainstem nuclei that regulate blood pressure.
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Affiliation(s)
- Bill J Yates
- Departments of Otolaryngology and Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania
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34
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Endo A, Fujita Y, Fuchigami T, Takahashi S, Mugishima H, Skatani K. Changes in cerebral blood oxygenation induced by active standing test in children with POTS and NMS. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 812:253-261. [PMID: 24729241 DOI: 10.1007/978-1-4939-0620-8_34] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Orthostatic dysregulation (OD) has been classified into subtypes by heart rate and blood pressure; however, the hemodynamics of brains have not yet been revealed. Therefore, we investigated changes in cerebral blood flow and oxygenation during an active standing test to clarify the pathophysiology of two subtypes: postural tachycardia syndrome (POTS) and neurally mediated syncope (NMS). We studied 31 children (15 boys, 16 girls; mean age, 14.0 ± 1.7 years) who presented with OD at the Department of Pediatrics and Child Health, Nihon University School of Medicine between 2009 and 2011. OD was diagnosed using the Japanese clinical guidelines for juvenile orthostatic dysregulation. After a 10-min resting period in the supine position, patients were asked to quickly stand up and keep upright for 10 min. Cerebral blood flow and cerebral oxygenation were measured using transcranial Doppler sonography and near-infrared spectroscopy. POTS showed a significant decrease of oxy-Hb and resistance index (RI), suggesting transient ischemia with maintainable cerebral autoregulation. NMS showed a decrease of oxy-Hb and an increase of RI, suggesting ischemia and impairment of autoregulation.
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Affiliation(s)
- Ayumi Endo
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Yukihiko Fujita
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo, 173-8610, Japan.
| | - Tatsuo Fuchigami
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Shori Takahashi
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Hideo Mugishima
- Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Oyaguchi-Kamicho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Kaoru Skatani
- Department of Neurological Surgery, Nihon University School of Medicine, Tokyo, Japan.,Nihon University College of Engineering, Tokyo, Japan
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Immink RV, Pott FC, Secher NH, van Lieshout JJ. Hyperventilation, cerebral perfusion, and syncope. J Appl Physiol (1985) 2013; 116:844-51. [PMID: 24265279 DOI: 10.1152/japplphysiol.00637.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This review summarizes evidence in humans for an association between hyperventilation (HV)-induced hypocapnia and a reduction in cerebral perfusion leading to syncope defined as transient loss of consciousness (TLOC). The cerebral vasculature is sensitive to changes in both the arterial carbon dioxide (PaCO2) and oxygen (PaO2) partial pressures so that hypercapnia/hypoxia increases and hypocapnia/hyperoxia reduces global cerebral blood flow. Cerebral hypoperfusion and TLOC have been associated with hypocapnia related to HV. Notwithstanding pronounced cerebrovascular effects of PaCO2 the contribution of a low PaCO2 to the early postural reduction in middle cerebral artery blood velocity is transient. HV together with postural stress does not reduce cerebral perfusion to such an extent that TLOC develops. However when HV is combined with cardiovascular stressors like cold immersion or reduced cardiac output brain perfusion becomes jeopardized. Whether, in patients with cardiovascular disease and/or defect, cerebral blood flow cerebral control HV-induced hypocapnia elicits cerebral hypoperfusion, leading to TLOC, remains to be established.
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Affiliation(s)
- R V Immink
- Laboratory for Clinical Cardiovascular Physiology, Department of Anatomy, Embryology, and Physiology, AMC Center for Heart Failure Research, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
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Laughlin MH, Davis MJ, Secher NH, van Lieshout JJ, Arce-Esquivel AA, Simmons GH, Bender SB, Padilla J, Bache RJ, Merkus D, Duncker DJ. Peripheral circulation. Compr Physiol 2013; 2:321-447. [PMID: 23728977 DOI: 10.1002/cphy.c100048] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Blood flow (BF) increases with increasing exercise intensity in skeletal, respiratory, and cardiac muscle. In humans during maximal exercise intensities, 85% to 90% of total cardiac output is distributed to skeletal and cardiac muscle. During exercise BF increases modestly and heterogeneously to brain and decreases in gastrointestinal, reproductive, and renal tissues and shows little to no change in skin. If the duration of exercise is sufficient to increase body/core temperature, skin BF is also increased in humans. Because blood pressure changes little during exercise, changes in distribution of BF with incremental exercise result from changes in vascular conductance. These changes in distribution of BF throughout the body contribute to decreases in mixed venous oxygen content, serve to supply adequate oxygen to the active skeletal muscles, and support metabolism of other tissues while maintaining homeostasis. This review discusses the response of the peripheral circulation of humans to acute and chronic dynamic exercise and mechanisms responsible for these responses. This is accomplished in the context of leading the reader on a tour through the peripheral circulation during dynamic exercise. During this tour, we consider what is known about how each vascular bed controls BF during exercise and how these control mechanisms are modified by chronic physical activity/exercise training. The tour ends by comparing responses of the systemic circulation to those of the pulmonary circulation relative to the effects of exercise on the regional distribution of BF and mechanisms responsible for control of resistance/conductance in the systemic and pulmonary circulations.
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Affiliation(s)
- M Harold Laughlin
- Department of Medical Pharmacology and Physiology, and the Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA.
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Abstract
Orthostatic hypotension (OH) is a relatively common heterogenous and multifactorial disorder, traditionally classified as neurogenic (less common but often more severe) or nonneurogenic (more common, with no direct signs of autonomic nervous system disease). The different clinical variants of orthostatic intolerance include initial, classical and delayed OH as well as postural tachycardia syndrome. Orthostatic instability may induce syncopal attacks either alone or in combination with other mechanisms, and is often dismissed as a precipitating factor. Moreover, prevalent OH is an independent risk factor for all-cause mortality and cardiovascular morbidity, and the majority of patients with OH are asymptomatic or have few nonspecific symptoms. Management of symptomatic orthostatic intolerance includes both nonpharmacological and pharmacological methods, but it is not always successful and may lead to complications. Future studies of OH should focus on mechanisms that lead to neurogenic and nonneurogenic OH, novel diagnostic methods and more effective therapeutic modalities.
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Affiliation(s)
- A Fedorowski
- Department of Clinical Sciences, Clinical Research Center, Lund University, Malmö, Sweden.
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39
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Wieling W, Krediet CTP, Solari D, de Lange FJ, van Dijk N, Thijs RD, van Dijk JG, Brignole M, Jardine DL. At the heart of the arterial baroreflex: a physiological basis for a new classification of carotid sinus hypersensitivity. J Intern Med 2013; 273:345-58. [PMID: 23510365 DOI: 10.1111/joim.12042] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The aim of this review is to provide an update of the current knowledge of the physiological mechanisms underlying reflex syncope. Carotid sinus syncope will be used as the classical example of an autonomic reflex with relatively well-established afferent, central and efferent pathways. These pathways, as well as the pathophysiology of carotid sinus hypersensitivity (CSH) and the haemodynamic effects of cardiac standstill and vasodilatation will be discussed. We will demonstrate that continuous recordings of arterial pressure provide a better understanding of the cardiovascular mechanisms mediating arterial hypotension and cerebral hypoperfusion in patients with reflex syncope. Finally we will demonstrate that the current criteria to diagnose CSH are too lenient and that the conventional classification of carotid sinus syncope as cardioinhibitory, mixed and vasodepressor subtypes should be revised because isolated cardioinhibitory CSH (asystole without a fall in arterial pressure) does not occur. Instead, we suggest that all patients with CSH should be thought of as being 'mixed', between cardioinhibition and vasodepression. The proposed stricter set of criteria for CSH should be evaluated in future studies.
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Affiliation(s)
- W Wieling
- Department of Internal Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands.
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Xu WH, Wang H, Hu YH, Wang B, Chen J, Gao S. Supine-to-standing transcranial Doppler test in patients with multiple system atrophy. Parkinsonism Relat Disord 2013; 19:539-42. [PMID: 23466059 DOI: 10.1016/j.parkreldis.2013.01.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 12/13/2012] [Accepted: 01/31/2013] [Indexed: 10/27/2022]
Abstract
BACKGROUND Supine-to-standing test, a transcranial Doppler (TCD) based technique, has been recently developed to evaluate cardiovascular dysautonomia. We explored the value of supine-to-standing TCD test in predicting the course of multiple system atrophy (MSA) with orthostatic hypotension (OH). METHODS By monitoring the signals of middle cerebral artery during supine-to-standing posture changes, the trend curves of cerebral blood flow velocities, pulsatility index and resistance index were obtained from 38 MSA patients with OH and 31 healthy subjects. The correlation between TCD findings and the clinical outcome of the patients, which was determined by follow-up structured phone interview, was analyzed. Adverse outcome was defined if a patient died, was in bed-ridden state or had recurrent syncope (>1 per month). RESULTS Two characteristic TCD findings were revealed in the MSA patients but not in the controls, i.e. a blunted cerebral blood flow velocity rebound after standing and/or sustained higher pulsatility index upon standing than supine baseline. Structured phone interview was completed in 31 of the 38 patients (mean follow-up time, 20 ± 11 months). While no subject had recurrent syncope before enrollment, 12 patients developed an adverse outcome during follow-up. The coexistence of two characteristic TCD findings predicted adverse outcomes with positive predictive value 66.7% and negative predictive value 87.5%. CONCLUSIONS Supine-to-standing TCD test is valuable in predicting the course of MSA with OH at early stage. We hypothesize baroreflex failure effects and paradoxical cerebral vasoconstriction in response to OH may account for the TCD findings in MSA patients.
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Affiliation(s)
- Wei-Hai Xu
- Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Beijing 1000730, China.
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Sun J, Sang H, Yang C, Dong H, Lei C, Lu Y, Ma Y, Zhou X, Sun X, Xiong L. Electroacupuncture improves orthostatic tolerance in healthy individuals via improving cardiac function and activating the sympathetic system. Europace 2012; 15:127-34. [PMID: 22791300 DOI: 10.1093/europace/eus220] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Orthostatic intolerance (OI) is a common clinical problem; however, effective and applicable clinical prevention/treatment is limited. The aim of this study was to investigate whether electroacupuncture (EA) is a novel effective treatment in attenuating OI in healthy individuals. METHODS AND RESULTS This study used a randomized, controlled, crossover design using two protocols. Orthostatic intolerance was induced with a combination of head-up tilt (HUT) and lower body negative pressure (LBNP). Twenty healthy individuals in Protocol 1 and 10 healthy individuals in Protocol 2 received no EA, EA at PC-6 acupuncture points (acupoint), and EA at a non-acupoint in a random order with an interim of 1 week. Electroacupuncture was administered prior to HUT/LBNP in Protocol 1 and simultaneously during HUT/LBNP in Protocol 2. Electroacupuncture at PC-6 administered either before or during HUT/LBNP postponed the occurrence of pre-syncopal symptoms, improved haemodynamic responses to HUT/LBNP (including increased diastolic blood pressure, stroke volume, and total peripheral resistance and a decreased heart rate), blunted decreases of maximum velocity and velocity time integral of blood flow in the middle cerebral artery, and increased plasma noradrenalin and adrenalin concentrations. In addition, heart rate variability analysis revealed that EA at PC-6 either before or during HUT/LBNP decreased high-frequency ranges of R-R interval while increasing low-frequency ranges of R-R interval, which indicates an elevated heart sympathetic tone. CONCLUSION Electroacupuncture at PC-6 is effective in improving orthostatic tolerance. Cardiac function improvement and sympathetic activation are responsible for the improved orthostatic tolerance after EA. EA represents a novel intervention against OI.
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Affiliation(s)
- Jing Sun
- Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
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Mitchell JR, Roach DE, Tyberg JV, Belenkie I, Sheldon RS. Mechanism of loss of consciousness during vascular neck restraint. J Appl Physiol (1985) 2012; 112:396-402. [DOI: 10.1152/japplphysiol.00592.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vascular neck restraint (VNR) is a technique that police officers may employ to control combative individuals. As the mechanism of unconsciousness is not completely understood, we tested the hypothesis that VNR simply compresses the carotid arteries, thereby decreasing middle cerebral artery blood flow. Twenty-four healthy police officers (age 35 ± 4 yr) were studied. Heart rate (HR), arterial pressure, rate of change of pressure (dP/d t), and stroke volume (SV) were measured using infrared finger photoplethysmography. Bilateral mean middle cerebral artery flow velocity (MCAVmean) was measured by using transcranial Doppler ultrasound. Neck pressure was measured using flat, fluid-filled balloon transducers positioned over both carotid bifurcations. To detect ocular fixation, subjects were asked to focus on a pen that was moved from side to side. VNR was released 1–2 s after ocular fixation. Ocular fixation occurred in 16 subjects [time 9.5 ± 0.4 (SE) s]. Pressures over the right (R) and left (L) carotid arteries were 257 ± 22 and 146 ± 18 mmHg, respectively. VNR decreased MCAVmean (R 45 ± 3 to 8 ± 4 cm/s; L 53 ± 2 to 10 ± 3 cm/s) and SV (92 ± 4 to 75 ± 4 ml; P < 0.001). Mean arterial pressure (MAP), dP/d t, and HR did not change significantly. We conclude that the most important mechanism in loss of consciousness was decreased cerebral blood flow caused by carotid artery compression. The small decrease in CO (9.6 to 7.5 l/min) observed would not seem to be important as there was no change in MAP. In addition, with no significant change in HR, ventricular contractility, or MAP, the carotid sinus baroreceptor reflex appears to contribute little to the response to VNR.
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Affiliation(s)
- Jamie R. Mitchell
- Departments of 1Cardiac Sciences,
- Physiology and Pharmacology,
- The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Dan E. Roach
- Departments of 1Cardiac Sciences,
- Physiology and Pharmacology,
- The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - John V. Tyberg
- Departments of 1Cardiac Sciences,
- Physiology and Pharmacology,
- The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Israel Belenkie
- Departments of 1Cardiac Sciences,
- Medicine, and
- The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Robert S. Sheldon
- Departments of 1Cardiac Sciences,
- Medicine, and
- The Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
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Poda R, Guaraldi P, Solieri L, Calandra-Buonaura G, Marano G, Gallassi R, Cortelli P. Standing worsens cognitive functions in patients with neurogenic orthostatic hypotension. Neurol Sci 2011; 33:469-73. [DOI: 10.1007/s10072-011-0746-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 08/18/2011] [Indexed: 11/29/2022]
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Autonomic dysfunction affects cerebral neurovascular coupling. Clin Auton Res 2011; 21:395-403. [PMID: 21796357 DOI: 10.1007/s10286-011-0129-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Accepted: 05/17/2011] [Indexed: 10/17/2022]
Abstract
OBJECTIVE Autonomic failure (AF) affects the peripheral vascular system, but little is known about its influence on cerebrovascular regulation. Patients with familial amyloidotic polyneuropathy (FAP) were studied as a model for AF. METHODS Ten mild (FAPm), 10 severe (FAPs) autonomic dysfunction FAP patients, and 15 healthy controls were monitored in supine and sitting positions for arterial blood pressure (ABP) and heart rate (HR) with arterial volume clamping, and for blood flow velocity (BFV) in posterior (PCA) and contralateral middle cerebral arteries (MCA) with transcranial Doppler. Analysis included resting BFV, cerebrovascular resistance parameters (cerebrovascular resistance index, CVRi; resistance area product, RAP; and critical closing pressure, CrCP), and neurovascular coupling through visually evoked BFV responses in PCA (gain, rate time, attenuation, and natural frequency). RESULTS In non-stimulation conditions, in each position, there were no significant differences between the groups, regarding HR, BP, resting BFV, and vascular resistance parameters. Sitting ABP was higher than in supine in the three groups, although only significantly in controls. Mean BFV was lower in sitting in all the groups, lacking statistical significance only in FAPs PCA. CVRi and CrCP increased with sitting in all the groups, while RAP increased in controls but decreased in FAPm and FAPs. In visual stimulation conditions, FAPs comparing to controls had a significant decrease of natural frequency, in supine and sitting, and of rate time and gain in sitting position. INTERPRETATION These results demonstrate that cerebrovascular regulation is affected in FAP subjects with AF, and that it worsens with orthostasis.
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Minati L, Kress IU, Visani E, Medford N, Critchley HD. Intra- and extra-cranial effects of transient blood pressure changes on brain near-infrared spectroscopy (NIRS) measurements. J Neurosci Methods 2011; 197:283-8. [PMID: 21392529 PMCID: PMC3089735 DOI: 10.1016/j.jneumeth.2011.02.029] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 02/08/2011] [Accepted: 02/28/2011] [Indexed: 11/07/2022]
Abstract
Brain near-infrared spectroscopy (NIRS) is an emerging neurophysiological tool that combines straightforward activity localization with cost–economy, portability and patient compatibility. NIRS is proving its empirical utility across specific cognitive and emotional paradigms. However, a potential limitation is that it is not only sensitive to haemodynamic changes taking place in the cortex, and task-related cardiovascular responses expressed in the perfusion of extracranial layers may be confounding. Existing literature reports correlations between brain NIRS and systemic blood pressure, yet it falls short of establishing whether in normal participants the blood pressure changes encountered in experimental settings can have confounding effects. Here, we tested this hypothesis by performing two experimental manipulations while recording from superficial occipital cortex, encompassing striate and extrastriate regions. Visual stimulation with reversing chequerboards evoked cortical haemodynamic responses. Simultaneously and independently, transient systemic blood pressure changes were generated through rapid arm-raising. Shallow-penetration NIRS recordings, probing only extra-cerebral tissues, highlighted close haemodynamic coupling with blood pressure. A different coupling pattern was observed in deep-penetration recordings directed at haemodynamic signals from visual cortex. In absence of blood-pressure changes, NIRS signals tracked differences in visual stimulus duration. However when blood pressure was actively manipulated, this effect was absent and replaced by a very large pressure-related response. Our observations demonstrate that blood pressure fluctuations can exert confounding effects on brain NIRS, through expression in extracranial tissues and within the brain itself. We highlight the necessity for continuous blood pressure monitoring alongside brain NIRS, and for further research on methods to correct for physiological confounds.
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Affiliation(s)
- Ludovico Minati
- Department of Psychiatry, Brighton & Sussex Medical School (BSMS), Falmer, UK.
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Haubrich C, Pies K, Dafotakis M, Block F, Kloetzsch C, Diehl RR. Transcranial Doppler monitoring in Parkinson's disease: cerebrovascular compensation of orthostatic hypotension. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:1581-1587. [PMID: 20800957 DOI: 10.1016/j.ultrasmedbio.2010.06.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 05/25/2010] [Accepted: 06/22/2010] [Indexed: 05/29/2023]
Abstract
Despite of precipitous blood pressure falls in Parkinson's Disease (PD) patients, they may not experience syncope or postural complaints. Can cerebral blood flow regulation explain why orthostatic hypotension (OH) has often no accompanying symptoms? In patients with PD and OH (18 asymptomatic; 8 symptomatic), arterial blood pressure (ABP) as well as Doppler-detected cerebral blood flow velocity (CBFV) in middle and posterior cerebral arteries (MCA and PCA) were monitored during head-up tilt and compared with 25 controls and eight non-PD-OH patients. Analysis included the transfer function between slow spontaneous pressure and flow-oscillations. ABP and CBFV were maintained at significantly higher levels in asymptomatic than symptomatic PD-OH (ABP: 85.7 ± 10.5 vs. 66.9 ± 12.5%; MCA-FV: 83.3 ± 9.3 vs. 66.1 ± 6.8%; PCA-FV: 84.4 ± 12.2 vs. 65.9 ± 9.3% of supine). When orthostatic complaints occurred, CBFV depended directly on ABP changes (MCA r(2) = 0.64; PCA r(2) = 0.62; both p < 0.05). Despite of a tilt-induced blood pressure instability in PD-OH, the transfer function parameters did not differ from normal [phase: MCA: 46.6 ± 20.5°; PCA 39.2 ± 28.8°, gain: MCA 2.0 ± 0.7; PCA 2.9 ± 1.6)]. Results showed a normal autoregulatory response to downward blood pressure shifts in PD. Moreover, orthostatic blood pressure instability is compensated equally sufficient in anterior and posterior parts of cerebral circulation. Whether in PD patients, OH becomes symptomatic rather seems to depend on blood pressure falling below the autoregulated range.
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Müller R, Bundgaard-Nielsen M, Kehlet H. Orthostatic function and the cardiovascular response to early mobilization after breast cancer surgery. Br J Anaesth 2010; 104:298-304. [DOI: 10.1093/bja/aep381] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Edlow BL, Kim MN, Durduran T, Zhou C, Putt ME, Yodh AG, Greenberg JH, Detre JA. The effects of healthy aging on cerebral hemodynamic responses to posture change. Physiol Meas 2010; 31:477-95. [PMID: 20181999 DOI: 10.1088/0967-3334/31/4/002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aging is associated with an increased incidence of orthostatic hypotension, impairment of the baroreceptor reflex and lower baseline cerebral blood flow. The effect of aging on cerebrovascular autoregulation, however, remains to be fully elucidated. We used a novel optical instrument to assess microvascular cerebral hemodynamics in the frontal lobe cortex of 60 healthy subjects ranging from ages 20-78. Diffuse correlation spectroscopy (DCS) and near-infrared spectroscopy (NIRS) were used to measure relative cerebral blood flow (rCBF), total hemoglobin concentration (THC), oxyhemoglobin concentration (HbO(2)) and deoxyhemoglobin concentration (Hb). Cerebral hemodynamics were monitored for 5 min at each of the following postures: head-of-bed 30 degrees , supine, standing and supine. Supine-to-standing posture change caused significant declines in rCBF, THC and HbO(2), and an increase in Hb, across the age continuum (p < 0.01). Healthy aging did not alter postural changes in frontal cortical rCBF (p = 0.23) and was associated with a smaller magnitude of decline in HbO(2) (p < 0.05) during supine-to-standing posture change. We conclude that healthy aging does not alter postural changes in frontal cortical perfusion.
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Affiliation(s)
- Brian L Edlow
- Department of Neurology, University of Pennsylvania, Philadelphia, USA
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Abstract
Leg crossing increases arterial pressure and combats symptomatic orthostatic hypotension in patients with sympathetic failure. This study compared the central and cerebrovascular effects of leg crossing in patients with sympathetic failure and healthy controls. We addressed the relationship between MCA Vmean (middle cerebral artery blood velocity; using transcranial Doppler ultrasound), frontal lobe oxygenation [O2Hb (oxyhaemoglobin)] and MAP (mean arterial pressure), CO (cardiac output) and TPR (total peripheral resistance) in six patients (aged 37–67 years; three women) and age- and gender-matched controls during leg crossing. In the patients, leg crossing increased MAP from 58 (42–79) to 72 (52–89) compared with 84 (70–95) to 90 (74–94) mmHg in the controls. MCA Vmean increased from 55 (38–77) to 63 (45–80) and from 56 (46–77) to 64 (46–80) cm/s respectively (P<0.05), with a larger rise in O2Hb [1.12 (0.52–3.27)] in the patients compared with the controls [0.83 (−0.11 to 2.04) μmol/l]. In the control subjects, CO increased 11% (P<0.05) with no change in TPR. By contrast, in the patients, CO increased 9% (P<0.05), but also TPR increased by 13% (P<0.05). In conclusion, leg crossing improves cerebral perfusion and oxygenation both in patients with sympathetic failure and in healthy subjects. However, in healthy subjects, cerebral perfusion and oxygenation were improved by a rise in CO without significant changes in TPR or MAP, whereas in patients with sympathetic failure, cerebral perfusion and oxygenation were improved through a rise in MAP due to increments in both CO and TPR.
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A definition of normovolaemia and consequences for cardiovascular control during orthostatic and environmental stress. Eur J Appl Physiol 2010; 109:141-57. [PMID: 20052592 PMCID: PMC2861179 DOI: 10.1007/s00421-009-1346-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2009] [Indexed: 11/20/2022]
Abstract
The Frank–Starling mechanism describes the relationship between stroke volume and preload to the heart, or the volume of blood that is available to the heart—the central blood volume. Understanding the role of the central blood volume for cardiovascular control has been complicated by the fact that a given central blood volume may be associated with markedly different central vascular pressures. The central blood volume varies with posture and, consequently, stroke volume and cardiac output (\documentclass[12pt]{minimal}
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\begin{document}$$ \dot{Q} $$\end{document} do not increase further indicating that in the supine resting position the heart operates on the plateau of the Frank–Starling curve which, therefore, may be taken as a functional definition of normovolaemia. Since the capacity of the vascular system surpasses the blood volume, orthostatic and environmental stress including bed rest/microgravity, exercise and training, thermal loading, illness, and trauma/haemorrhage is likely to restrict venous return and \documentclass[12pt]{minimal}
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\begin{document}$$ \dot{Q} $$\end{document}. Consequently the cardiovascular responses are determined primarily by their effect on the central blood volume. Thus during environmental stress, flow redistribution becomes dependent on sympathetic activation affecting not only skin and splanchnic blood flow, but also flow to skeletal muscles and the brain. This review addresses the hypothesis that deviations from normovolaemia significantly influence these cardiovascular responses.
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