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Ji W, Nightingale TE, Zhao F, Fritz NE, Phillips AA, Sisto SA, Nash MS, Badr MS, Wecht JM, Mateika JH, Panza GS. The Clinical Relevance of Autonomic Dysfunction, Cerebral Hemodynamics, and Sleep Interactions in Individuals Living With SCI. Arch Phys Med Rehabil 2024; 105:166-176. [PMID: 37625532 DOI: 10.1016/j.apmr.2023.08.006] [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: 05/31/2023] [Revised: 07/25/2023] [Accepted: 08/06/2023] [Indexed: 08/27/2023]
Abstract
A myriad of physiological impairments is seen in individuals after a spinal cord injury (SCI). These include altered autonomic function, cerebral hemodynamics, and sleep. These physiological systems are interconnected and likely insidiously interact leading to secondary complications. These impairments negatively influence quality of life. A comprehensive review of these systems, and their interplay, may improve clinical treatment and the rehabilitation plan of individuals living with SCI. Thus, these physiological measures should receive more clinical consideration. This special communication introduces the under investigated autonomic dysfunction, cerebral hemodynamics, and sleep disorders in people with SCI to stakeholders involved in SCI rehabilitation. We also discuss the linkage between autonomic dysfunction, cerebral hemodynamics, and sleep disorders and some secondary outcomes are discussed. Recent evidence is synthesized to make clinical recommendations on the assessment and potential management of important autonomic, cerebral hemodynamics, and sleep-related dysfunction in people with SCI. Finally, a few recommendations for clinicians and researchers are provided.
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Affiliation(s)
- Wenjie Ji
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY
| | - Tom E Nightingale
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK; Centre for Trauma Science Research, University of Birmingham, Birmingham, UK; International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
| | - Fei Zhao
- Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, MI; John D. Dingell VA Medical Center, Research and Development, Detroit, MI
| | - Nora E Fritz
- Department of Health Care Sciences, Program of Physical Therapy, Detroit, MI; Department of Neurology, Wayne State University, Detroit, MI
| | - Aaron A Phillips
- Department of Physiology and Pharmacology, Cardiac Sciences, Clinical Neurosciences, Biomedical Engineering, Libin Cardiovascular institute, Hotchkiss Brain Institute, Cumming School of Medicine, Calgary, AB, Canada; RESTORE.network, University of Calgary, Calgary, AB, Canad
| | - Sue Ann Sisto
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY
| | - Mark S Nash
- Department of Neurological Surgery, Physical Medicine & Rehabilitation Physical Therapy, Miami, FL; Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL
| | - M Safwan Badr
- John D. Dingell VA Medical Center, Research and Development, Detroit, MI; Departments of Physiology and Internal Medicine, Wayne State University, Detroit, MI
| | - Jill M Wecht
- James J Peters VA Medical Center, Department of Spinal Cord Injury Research, Bronx, NY; Icahn School of Medicine Mount Sinai, Departments of Rehabilitation and Human Performance, and Medicine Performance, and Medicine, New York, NY
| | - Jason H Mateika
- John D. Dingell VA Medical Center, Research and Development, Detroit, MI; Departments of Physiology and Internal Medicine, Wayne State University, Detroit, MI
| | - Gino S Panza
- Department of Health Care Sciences, Program of Occupational Therapy, Wayne State University, Detroit, MI; John D. Dingell VA Medical Center, Research and Development, Detroit, MI.
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Hayes BD, Fossey MPM, Poormasjedi-Meibod MS, Erskine E, Soriano JE, Scott B, Rosentreter R, Granville DJ, Phillips AA, West CR. Experimental high thoracic spinal cord injury impairs the cardiac and cerebrovascular response to orthostatic challenge in rats. Am J Physiol Heart Circ Physiol 2021; 321:H716-H727. [PMID: 34448635 DOI: 10.1152/ajpheart.00239.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 08/24/2021] [Indexed: 11/22/2022]
Abstract
Spinal cord injury (SCI) impairs the cardiovascular responses to postural challenge, leading to the development of orthostatic hypotension (OH). Here, we apply lower body negative pressure (LBNP) to rodents with high-level SCI to demonstrate the usefulness of LBNP as a model for experimental OH studies, and to explore the effect of simulated OH on cardiovascular and cerebrovascular function following SCI. Male Wistar rats (n = 34) were subjected to a sham or T3-SCI surgery and survived into the chronic period postinjury (i.e., 8 wk). Cardiac function was tracked via ultrasound pre- to post-SCI to demonstrate the clinical utility of our model. At study termination, we conducted left-ventricular (LV) catheterization and insonated the middle cerebral artery to investigate the hemodynamic, cardiac, and cerebrovascular response to a mild dose of LBNP that is sufficient to mimic clinically defined OH in rats with T3-SCI but not sham animals. In response to mimicked OH, there was a greater decline in stroke volume, cardiac output, maximal LV pressure, and blood pressure in SCI compared with sham (P < 0.034), whereas heart rate was increased in sham but decreased in SCI (P < 0.029). SCI animals also had an exaggerated reduction in peak, minimum and mean middle cerebral artery flow, for a given change in blood pressure, in response to LBNP (P < 0.033), implying impaired dynamic cerebral autoregulation. Using a preclinical SCI model of OH, we demonstrate that complete high thoracic SCI impairs the cardiac response to OH and disrupts dynamic cerebral autoregulation.NEW & NOTEWORTHY This is the first use of LBNP to interrogate the cardiac and cerebrovascular responses to simulated OH in a preclinical study of SCI. Here, we demonstrate the utility of our simulated OH model and use it to demonstrate that SCI impairs the cardiac response to simulated OH and disrupts dynamic cerebrovascular autoregulation.
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Affiliation(s)
- Brian D Hayes
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mary Pauline Mona Fossey
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Experimental Medicine, Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Erin Erskine
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jan Elaine Soriano
- Departments of Physiology and Pharmacology, Cardiac Sciences, Clinical Neurosciences, Libin Cardiovascular Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Berkeley Scott
- Departments of Physiology and Pharmacology, Cardiac Sciences, Clinical Neurosciences, Libin Cardiovascular Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Ryan Rosentreter
- Departments of Physiology and Pharmacology, Cardiac Sciences, Clinical Neurosciences, Libin Cardiovascular Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - David J Granville
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Aaron A Phillips
- Departments of Physiology and Pharmacology, Cardiac Sciences, Clinical Neurosciences, Libin Cardiovascular Institute, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Christopher R West
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
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Gerega A, Wojtkiewicz S, Sawosz P, Kacprzak M, Toczylowska B, Bejm K, Skibniewski F, Sobotnicki A, Gacek A, Maniewski R, Liebert A. Assessment of the brain ischemia during orthostatic stress and lower body negative pressure in air force pilots by near-infrared spectroscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:1043-1060. [PMID: 32133236 PMCID: PMC7041453 DOI: 10.1364/boe.377779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 05/26/2023]
Abstract
A methodology for the assessment of the cerebral hemodynamic reaction to normotensive hypovolemia, reduction in cerebral perfusion and orthostatic stress leading to ischemic hypoxia and reduced muscular tension is presented. Most frequently, the pilots of highly maneuverable aircraft are exposed to these phenomena. Studies were carried out using the system consisting of a chamber that generates low pressure around the lower part of the body - LBNP (lower body negative pressure) placed on the tilt table. An in-house developed 6-channel NIRS system operating at 735 and 850 nm was used in order to assess the oxygenation of the cerebral cortex, based on measurements of diffusely reflected light in reflectance geometry. The measurements were carried out on a group of 12 active pilots and cadets of the Polish Air Force Academy and 12 healthy volunteers. The dynamics of changes in cerebral oxygenation was evaluated as a response to LBNP stimuli with a simultaneous rapid change of the tilt table angle. Parameters based on calculated changes of total hemoglobin concentration were proposed allowing to evaluate differences in reactions observed in control subjects and pilots/cadets. The results of orthogonal partial least squares-discriminant analysis based on these parameters show that the subjects can be classified into their groups with 100% accuracy.
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Affiliation(s)
- Anna Gerega
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Stanislaw Wojtkiewicz
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Piotr Sawosz
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Michal Kacprzak
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Beata Toczylowska
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Karolina Bejm
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Franciszek Skibniewski
- Technical Department of Aeromedical Research and Flight Simulators, Military Institute of Aviation Medicine, Warsaw, Poland
| | - Aleksander Sobotnicki
- Department of Research and Development, Institute of Medical Technology and Equipment, Zabrze, Poland
| | - Adam Gacek
- Department of Research and Development, Institute of Medical Technology and Equipment, Zabrze, Poland
| | - Roman Maniewski
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
| | - Adam Liebert
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
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Cerebral Blood Oxygenation Changes in Juvenile Patients with Delayed Orthostatic Hypotension During an Active Standing Test. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020. [PMID: 31893398 DOI: 10.1007/978-3-030-34461-0_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Delayed orthostatic hypotension (OH) is a minor subset of orthostatic dysregulation (OD). Cerebral blood oxygenation in juvenile patients with delayed OH has not been studied. We investigated the bilateral changes in cerebral oxygenation in the prefrontal cortex during an active standing test in 23 juvenile patients with delayed OH using near-infrared spectroscopy (NIRS). We measured the oxy-Hb, deoxy-Hb, and total-Hb during the active standing test. Four observations were made during the test: t1 in a resting supine position, t2 when maintaining blood pressure, and the remaining two (t3, t4) during hypotension. The concentration of oxy-Hb significantly decreased prior to satisfying the diagnostic criteria of delayed OH after standing and did not change thereafter. The concentration of deoxy-Hb increased gradually during the measurement periods. In addition, total-Hb increased from t2 to t3. There was no significant difference in the change in each Hb parameter between the left and right cerebral hemispheres. Our results indicate that NIRS parameters are more sensitive than blood pressure for the interpretation of cerebral autoregulation in juvenile patients with delayed OH.
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A comparison of static and dynamic cerebral autoregulation during mild whole-body cold stress in individuals with and without cervical spinal cord injury: a pilot study. Spinal Cord 2018; 56:469-477. [PMID: 29330514 DOI: 10.1038/s41393-017-0021-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/14/2017] [Accepted: 09/14/2017] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN Experimental study. OBJECTIVES To characterize static and dynamic cerebral autoregulation (CA) of individuals with cervical spinal cord injury (SCI) compared to able-bodied controls in response to moderate increases in mean arterial pressure (MAP) caused by mild whole-body cold stress. SETTING Japan METHODS: Five men with complete autonomic cervical SCI (sustained > 5 y) and six age-matched able-bodied men participated in hemodynamic, temperature, catecholamine and respiratory measurements for 60 min during three consecutive stages: baseline (10 min; 33 °C water through a thin-tubed whole-body suit), mild cold stress (20 min; 25 °C water), and post-cold recovery (30 min; 33 °C water). Static CA was determined as the ratio between mean changes in middle cerebral artery blood velocity and MAP, dynamic CA as transfer function coherence, gain, and phase between spontaneous changes in MAP to middle cerebral artery blood velocity. RESULTS MAP increased in both groups during cold and post-cold recovery (mean differences: 5-10 mm Hg; main effect of time: p = 0.001). Static CA was not different between the able-bodied vs. the cervical SCI group (mean (95% confidence interval (CI)) of between-group difference: -4 (-11 to 3) and -2 (-5 to 1) cm/s/mm Hg for cold (p = 0.22) and post-cold (p = 0.24), respectively). At baseline, transfer function phase was shorter in the cervical SCI group (mean (95% CI) of between-group difference: 0.6 (0.2 to 1.0) rad; p = 0.006), while between-group differences in changes in phase were not different in response to the cold stress (interaction term: p = 0.06). CONCLUSIONS This pilot study suggests that static CA is similar between individuals with cervical SCI and able-bodied controls in response to moderate increases in MAP, while dynamic CA may be impaired in cervical SCI because of disturbed sympathetic control.
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Wecht JM, Bauman WA. Implication of altered autonomic control for orthostatic tolerance in SCI. Auton Neurosci 2018; 209:51-58. [DOI: 10.1016/j.autneu.2017.04.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 03/16/2017] [Accepted: 04/25/2017] [Indexed: 12/22/2022]
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Kay VL, Rickards CA. Reproducibility of a continuous ramp lower body negative pressure protocol for simulating hemorrhage. Physiol Rep 2015; 3:3/11/e12640. [PMID: 26607173 PMCID: PMC4673656 DOI: 10.14814/phy2.12640] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Central hypovolemia elicited by application of lower body negative pressure (LBNP) has been used extensively to simulate hemorrhage in human subjects. Traditional LBNP protocols incorporate progressive steps in pressure held for specific time intervals. The aim of this study was to assess the reproducibility of applying continuous LBNP at a constant rate until presyncope to replicate actual bleeding. During two trials (≥4 weeks intervening), LBNP was applied at a rate of 3 mmHg/min in 18 healthy human subjects (12M; 6F) until the onset of presyncopal symptoms. Heart rate (HR), mean arterial pressure (MAP), stroke volume (SV), total peripheral resistance (TPR), mean middle and posterior cerebral artery velocities (MCAv, PCAv), and cerebral oxygen saturation (ScO2) were measured continuously. Time to presyncope (TTPS) and hemodynamic responses were compared between the two trials. TTPS (1649 ± 98 sec vs. 1690 ± 88 sec; P = 0.47 [t-test]; r = 0.77) and the subsequent magnitude of central hypovolemia (%Δ SV −54 ± 4% vs. −53 ± 4%; P = 0.55) were similar between trials. There were no statistically distinguishable differences at either baseline (P ≥ 0.17) or presyncope between trials for HR, MAP, TPR, mean MCAv, mean PCAv, or ScO2 (P ≥ 0.19). The rate of change from baseline to presyncope for all hemodynamic responses was also similar between trials (P ≥ 0.12). Continuous LBNP applied at a rate of 3 mmHg/min was reproducible in healthy human subjects, eliciting similar reductions in central blood volume and subsequent reflex hemodynamic responses.
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Affiliation(s)
- Victoria L Kay
- Institute for Cardiovascular & Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Caroline A Rickards
- Institute for Cardiovascular & Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
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Bleton H, Sejdić E. A cerebral blood flow evaluation during cognitive tasks following a cervical spinal cord injury: a case study using transcranial Doppler recordings. Cogn Neurodyn 2015; 9:615-26. [PMID: 26557931 DOI: 10.1007/s11571-015-9355-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 06/15/2015] [Accepted: 08/27/2015] [Indexed: 10/23/2022] Open
Abstract
A spinal cord injury (SCI) is one of the most common neurological disorders. In this paper, we examined the consequences of upper SCI in a male participant on the cerebral blood flow velocity. In particular, transcranial Doppler was used to study these effects through middle cerebral arteries (MCA) during resting-state periods and during cognitive challenges (non-verbal word-generation tasks and geometric-rotation tasks). Signal characteristics were analyzed from raw signals and envelope signals (maximum velocity) in the time domain, the frequency domain and the time-frequency domain. The frequency features highlighted an increase of the peak frequency in L-MCA and R-MCA raw signals, which revealed stronger cerebral blood flow during geometric/verbal processes respectively. This underlined a slight dominance of the right hemisphere during word-generation periods and a slight dominance of the left hemisphere during geometric processes. This finding was confirmed by cross-correlation in the time domain and by the entropy rate in information-theoretic domain. A comparison of our results to other neurological disorders (Alzheimer's disease, Parkinson's disease, autism, epilepsy, traumatic brain injury) showed that the SCI had similar effects such as general decreased cerebral blood flow and similar regular hemispheric dominance in a few cases.
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Affiliation(s)
- Héloïse Bleton
- Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, PA 15261 USA
| | - Ervin Sejdić
- Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, PA 15261 USA
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Phillips AA, Ainslie PN, Krassioukov AV, Warburton DER. Regulation of cerebral blood flow after spinal cord injury. J Neurotrauma 2013; 30:1551-63. [PMID: 23758347 DOI: 10.1089/neu.2013.2972] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Significant cardiovascular and autonomic dysfunction occurs after era spinal cord injury (SCI). Two major conditions arising from autonomic dysfunction are orthostatic hypotension and autonomic dysreflexia (i.e., severe acute hypertension). Effective regulation of cerebral blood flow (CBF) is essential to offset these drastic changes in cerebral perfusion pressure. In the context of orthostatic hypotension and autonomic dysreflexia, the purpose of this review is to critically examine the mechanisms underlying effective CBF after an SCI and propose future avenues for research. Although only 16 studies have examined CBF control in those with high-level SCI (above the sixth thoracic spinal segment), it appears that CBF regulation is markedly altered in this population. Cerebrovascular function comprises three major mechanisms: (1) cerebral autoregulation, (i.e., ΔCBF/Δ blood pressure); (2) cerebrovascular reactivity to changes in PaCO2 (i.e. ΔCBF/arterial gas concentration); and (3) neurovascular coupling (i.e., ΔCBF/Δ metabolic demand). While static cerebral autoregulation appears to be well maintained in high-level SCI, dynamic cerebral autoregulation, cerebrovascular reactivity, and neurovascular coupling appear to be markedly altered. Several adverse complications after high-level SCI may mediate the changes in CBF regulation including: systemic endothelial dysfunction, sleep apnea, dyslipidemia, decentralization of sympathetic control, and dominant parasympathetic activity. Future studies are needed to describe whether altered CBF responses after SCI aid or impede orthostatic tolerance. Further, simultaneous evaluation of extracranial and intracranial CBF, combined with modern structural and functional imaging, would allow for a more comprehensive evaluation of CBF regulatory processes. We are only beginning to understand the functional effects of dysfunctional CBF regulation on brain function on persons with SCI, which are likely to include increased risk of transient ischemic attacks, stroke, and cognitive dysfunction.
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Affiliation(s)
- Aaron A Phillips
- Cardiovascular Physiology and Rehabilitation Laboratory, University of British Columbia, Vancouver, Canada
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Cerebrovascular autoregulation: lessons learned from spaceflight research. Eur J Appl Physiol 2012; 113:1909-17. [PMID: 23132388 DOI: 10.1007/s00421-012-2539-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 10/24/2012] [Indexed: 10/27/2022]
Abstract
This review summarizes our current understanding of cerebral blood flow regulation with exposure to microgravity, outlines potential mechanisms associated with post-flight orthostatic intolerance, and proposes future directions for research and linkages with cerebrovascular disorders found in the general population. It encompasses research from cellular mechanisms (e.g. hind limb suspension: tissue, animal studies) to whole body analysis with respect to understanding human responses using space analogue studies (bed rest, parabolic flight) as well as data collected before, during, and after spaceflight. Recent evidence indicates that cerebrovascular autoregulation may be impaired in some astronauts leading to increased susceptibility to syncope upon return to a gravitational environment. The proposed review not only provides insights into the mechanisms of post-flight orthostatic intolerance, but also increases our understanding of the mechanisms associated with pathophysiological conditions (e.g. unexplained syncope) with clinical applications in relation to postural hypotension or intradialytic hypotension.
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Phillips AA, Krassioukov AV, Ainslie PN, Warburton DE. Baroreflex Function after Spinal Cord Injury. J Neurotrauma 2012; 29:2431-45. [DOI: 10.1089/neu.2012.2507] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Aaron A. Phillips
- Cardiovascular Physiology and Rehabilitation Laboratory, Physical Activity Promotion and Chronic Disease Prevention Unit, University of British Columbia, British Columbia, Canada
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
| | - Andrei V. Krassioukov
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
- Division of Physical Medicine and Rehabilitation, Department of Medicine, University of British Columbia, British Columbia, Canada
| | - Philip N. Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Darren E.R. Warburton
- Cardiovascular Physiology and Rehabilitation Laboratory, Physical Activity Promotion and Chronic Disease Prevention Unit, University of British Columbia, British Columbia, Canada
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
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Sahota IS, Ravensbergen HRJC, McGrath MS, Claydon VE. Cerebrovascular responses to orthostatic stress after spinal cord injury. J Neurotrauma 2012; 29:2446-56. [PMID: 22720841 DOI: 10.1089/neu.2012.2379] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Orthostatic hypotension (OH) is a debilitating condition affecting individuals with spinal cord injury (SCI) that may be associated with cerebral hypoperfusion. We studied orthostatic cerebral control in individuals with SCI with different levels and severities of injury to spinal cardiovascular autonomic pathways. We measured beat-to-beat cardiovascular and cerebrovascular responses to passive orthostatic stress in 16 controls and 26 subjects with chronic SCI. Cerebrovascular control was assessed from diastolic cerebral blood flow velocity (CBFV(D)), and indices of static and dynamic cerebral autoregulation. Severity of autonomic injury was inferred from spectral analyses of systolic arterial pressure, and supine plasma noradrenaline concentrations. Symptoms of OH were evaluated using questionnaires. CBFV(D) decreased during orthostasis only in individuals with autonomically complete injuries above T6. Orthostatic CBFV(D) was significantly correlated (p<0.05) with the severity of autonomic injury. Individuals with injuries above T6 had impaired dynamic autoregulation (p<0.05) compared to controls, and this was correlated (p<0.05) with the severity of autonomic injury. Individuals with autonomically complete SCI reported increased severity of symptoms relative to controls (p<0.05). Symptom severity was correlated with the efficacy of dynamic autoregulation. During orthostatic stress, SCI individuals have impaired cerebrovascular control that is related to the level and severity of autonomic injury.
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Affiliation(s)
- Inderjeet S Sahota
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, British Columbia, Canada
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Kim YT, Tanaka H, Takaya R, Kajiura M, Tamai H, Arita M. Quantitative study on cerebral blood volume determined by a near-infrared spectroscopy during postural change in children. Acta Paediatr 2009; 98:466-71. [PMID: 19183359 DOI: 10.1111/j.1651-2227.2008.01113.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM To investigate changes in cerebral blood volume during standing in healthy children with or without abnormal cardiovascular responses. METHODS We studied 53 children (age, 10-15 years). Cerebral oxygenated haemoglobin (oxy-Hb) and deoxygenated Hb (deoxy-Hb) were non-invasively and continuously measured using near-infrared spectroscopy (NIRS) (NIRO 300, Hamamatsu Photomedics, Shizuoka, Japan) during active standing. Beat-to-beat arterial pressure was monitored by Portapres. RESULTS Of 49 children with complete data acquisition, 33 had a normal cardiovascular response to the test (Group I) and 16 showed an abnormal response (Group II); nine with instantaneous orthostatic hypotension, three with postural tachycardia syndrome, three with neutrally mediated syncope and one with delayed orthostatic hypotension. At the onset of standing, Group II showed a significantly larger fall of oxy-Hb than Group I did (-2.9 +/- 2.8 micromol/L vs. -6.4 +/- 7.2 micromol/L, respectively, p < 0.05). During min 1 to 7 of standing, with one exception, changes in oxy-Hb were normally distributed over the level of -4 micromol/L in Group I. Group II also showed a significantly marked decrease in oxy-Hb compared to Group I. Decreases in oxy-Hb were not correlated with blood pressure changes. CONCLUSION This study shows that precise change in cerebral blood volume caused by orthostatic stress can be determined by NIRS in children in a quantitative manner of NIRS. Children with abnormal circulatory responses to standing showed a significant reduction of oxy-Hb compared with normal counterparts, suggesting impairment of cerebral autoregulation in these children.
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Handrakis JP, DeMeersman RE, Rosado-Rivera D, LaFountaine MF, Spungen AM, Bauman WA, Wecht JM. Effect of hypotensive challenge on systemic hemodynamics and cerebral blood flow in persons with tetraplegia. Clin Auton Res 2008; 19:39-45. [PMID: 18850311 DOI: 10.1007/s10286-008-0496-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Accepted: 08/29/2008] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Individuals with tetraplegia have impaired central control of sympathetic vascular modulation and blood pressure (BP); how this impairment affects cerebral blood flow (CBF) is unclear. OBJECTIVES To determine if persons with tetraplegia maintain CBF similarly to able-bodied controls after a hypotensive challenge. METHODS Seven individuals with chronic tetraplegia and seven age-matched, non-SCI control subjects underwent a hypotensive challenge consisting of angiotensin-converting enzyme (ACE) inhibition (1.25 mg enalaprilat) and 45 degrees head-up tilt (HUT). Heart rate (HR), low frequency systolic BP variability (LFsbp), brachial mean arterial pressure (MAP) and middle cerebral artery CBF were measured before and after the challenge. Group differences for the baseline (BL) to post-challenge response were determined by repeated measures ANOVA. RESULTS HR did not differ between the groups in response to the hypotensive challenge. LFsbp response was significantly reduced in the tetra compared to the control group (-38 +/- 51 vs. 72 +/- 93%, respectively). MAP did not differ between the groups at BL but was significantly lower in the tetra compared to the control group post-challenge (55 +/- 13 vs. 71 +/- 9 mmHg, respectively); the percent change in MAP was significantly greater in the tetra than in the control group (-29 +/- 14.1 vs. -13 +/- 9%, respectively). However, CBF did not differ between the groups at baseline or post-challenge; the percent change in CBF post-challenge was not different between the tetra and control groups (-29 +/- 13.2 vs. -23 +/- 10.3%, respectively). INTERPRETATION Despite impaired sympathetic vasomotor and BP control, CBF in persons with tetraplegia was comparable to that of control subjects during a hypotensive challenge.
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Affiliation(s)
- John P Handrakis
- Center of Excellence for the Medical Consequences of Spinal Cord Injury, James J. Peters VA Medical Center, 130 West Kingsbridge Road, Bronx, NY 10468, USA.
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Chao CY, Cheing GL. Orthostatic Hypotension for People with Spinal Cord Injuries. Hong Kong Physiother J 2008. [DOI: 10.1016/s1013-7025(09)70008-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Tran CCD, Berthelot M, Etienne X, Van Beers P, Dussault C, Jouanin JC. Brief exposure to -2 Gz reduces cerebral oxygenation in response to stand test. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 599:163-8. [PMID: 17727261 DOI: 10.1007/978-0-387-71764-7_22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The aim of the present experiment was to determine whether a single 30 s of exposure to -2 Gz (foot-to-head inertial forces) as orthostatic stress results in altered brain oxygenation control in response to active standing. Cerebral oxygenation (oxy-Hb), cerebral blood volume (CBV), and mean arterial blood pressure at brain level (MAPbrain) were recorded in 12 subjects in supine and then in standing position (10 min), before and after -2 Gz centrifugation. The decrease in oxy-Hb (-5 +/- 9 vs. -9 +/- 10 microM, P < 0.001) and in CBV (-2 +/- 11 vs. -4 +/- 12 microM, P < 0.05) upon standing was more important after -2 Gz centrifugation, with unchanged MAPbrain (-6 +/- 7 vs. -6 +/- 9 mmHg). These findings suggest a downward shift in the static cerebral autoregulation curve.
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Affiliation(s)
- Cong C D Tran
- Institut de médecine aérospatiale du service de santé des armées, BP 73, 91223 Brétigny/Orge, France
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Claydon VE, Steeves JD, Krassioukov A. Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology. Spinal Cord 2005; 44:341-51. [PMID: 16304564 DOI: 10.1038/sj.sc.3101855] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Motor and sensory deficits are well-known consequences of spinal cord injury (SCI). During the last decade, a significant number of experimental and clinical studies have focused on the investigation of autonomic dysfunction and cardiovascular control following SCI. Numerous clinical reports have suggested that unstable blood pressure control in individuals with SCI could be responsible for their increased cardiovascular mortality. The aim of this review is to outline the incidence and pathophysiological mechanisms underlying the orthostatic hypotension that commonly occurs following SCI. We describe the clinical abnormalities of blood pressure control following SCI, with particular emphasis upon orthostatic hypotension. Possible mechanisms underlying orthostatic hypotension in SCI, such as changes in sympathetic activity, altered baroreflex function, the lack of skeletal muscle pumping activity, cardiovascular deconditioning and altered salt and water balance will be discussed. Possible alterations in cerebral autoregulation following SCI, and the impact of these changes upon cerebral perfusion are also examined. Finally, the management of orthostatic hypotension will be considered.
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Affiliation(s)
- V E Claydon
- International Collaboration On Repair Discoveries (ICORD), University of British Columbia, Vancouver, Canada
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Tran CCD, Berthelot M, Etienne X, Dussault C, Jouanin JC, Van Beers P, Serra A, Guézennec CY. Cerebral oxygenation declines despite maintained orthostatic tolerance after brief exposure to gravitational stress. Neurosci Lett 2005; 380:181-6. [PMID: 15854774 DOI: 10.1016/j.neulet.2005.01.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2004] [Revised: 01/07/2005] [Accepted: 01/13/2005] [Indexed: 11/21/2022]
Abstract
We examined the effect of a single 120 s of exposure to +3Gz (head-to-foot inertial forces) centrifugation as orthostatic stress on cerebral oxygenation (oxy-Hb) and cerebral blood volume (CBV) changes in response to stand test, in order to relate the occurrence of altered cerebral oxygenation control to any increase in sympathetic activity. Frontal near-infrared spectroscopy and mean arterial blood pressure at brain level (MAPbrain) were recorded in 14 subjects in supine and then in standing (10 min) position, before and after +3Gz centrifugation. The decrease in oxy-Hb (-7 +/- 5 a.u. versus -27 +/- 4 a.u., P<0.001) and in CBV (-6 +/- 10 a.u. versus -15 +/- 8 a.u., P<0.05) upon standing was more important after +3Gz centrifugation, with unchanged MAPbrain (-8 +/- 8 mmHg versus -3 +/- 11 mmHg). Upon standing, the high-frequency component of heart rate was lower (1090 +/- 460 ms2 versus 827 +/- 412 ms2, P<0.05) after +3Gz centrifugation. These findings suggest a downward shift in the static cerebral autoregulatory curve. We conclude that cerebral vasoconstriction might have occurred without centrally mediated increase in the entire peripheral sympathetic activity of the body.
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Affiliation(s)
- Cong Chi Denis Tran
- Département Physiologie, Institut de Médecine Aérospatiale du Service de Santé des Armées, B.P. 73, 91223 Brétigny-sur-Orge Cédex, France.
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Brown CM, Dütsch M, Hecht MJ, Neundörfer B, Hilz MJ. Assessment of cerebrovascular and cardiovascular responses to lower body negative pressure as a test of cerebral autoregulation. J Neurol Sci 2003; 208:71-8. [PMID: 12639728 DOI: 10.1016/s0022-510x(02)00438-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to determine whether lower body negative pressure (LBNP), combined with noninvasive methods of assessing changes in systemic and cerebral vascular resistance, is suitable as a method for assessing cerebral autoregulation. In 13 subjects we continuously assessed heart rate, blood pressure, cerebral blood flow velocity (CBFV) and cardiac output during graded levels of LBNP from 0 to -50 mm Hg. With increasing levels of LBNP, cardiac output declined significantly (to 55.8+/-4.5% of baseline value) but there was no overall change in mean arterial pressure. CBFV also fell at higher levels of LBNP (to 81.4+/-3.2% of baseline) but the percentage CBFV change was significantly less than that in cardiac output (P<0.01). The maximum increase in cerebrovascular resistance (pulsatility ratio) was significantly less than that in total peripheral resistance (17+/-6% vs. 105+/-16%, P<0.01). Spectral analysis showed that the power of low-frequency oscillations in mean arterial pressure, but not CBFV, increased significantly at the -50 mm Hg level of LBNP. These results show that, even during high levels of orthostatic stress, cerebral autoregulation is preserved and continues to protect the cerebral circulation from changes in the systemic circulation. Furthermore, assessment of cardiovascular and cerebrovascular parameters during LBNP may provide a useful clinical test of cerebral autoregulation.
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Affiliation(s)
- Clive M Brown
- Autonomic Laboratory, Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, Germany.
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