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Turner R, Rasmussen P, Gatterer H, Tremblay JC, Roche J, Strapazzon G, Roveri G, Lawley J, Siebenmann C. Cerebral blood flow regulation in hypobaric hypoxia: role of haemoconcentration. J Physiol 2024. [PMID: 38687185 DOI: 10.1113/jp285169] [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: 06/19/2023] [Accepted: 04/04/2024] [Indexed: 05/02/2024] Open
Abstract
During acute hypoxic exposure, cerebral blood flow (CBF) increases to compensate for the reduced arterial oxygen content (CaO2). Nevertheless, as exposure extends, both CaO2 and CBF progressively normalize. Haemoconcentration is the primary mechanism underlying the CaO2 restoration and may therefore explain, at least in part, the CBF normalization. Accordingly, we tested the hypothesis that reversing the haemoconcentration associated with extended hypoxic exposure returns CBF towards the values observed in acute hypoxia. Twenty-three healthy lowlanders (12 females) completed two identical 4-day sojourns in a hypobaric chamber, one in normoxia (NX) and one in hypobaric hypoxia (HH, 3500 m). CBF was measured by ultrasound after 1, 6, 12, 48 and 96 h and compared between sojourns to assess the time course of changes in CBF. In addition, CBF was measured at the end of the HH sojourn after hypervolaemic haemodilution. Compared with NX, CBF was increased in HH after 1 h (P = 0.001) but similar at all later time points (all P > 0.199). Haemoglobin concentration was higher in HH than NX from 12 h to 96 h (all P < 0.001). While haemodilution reduced haemoglobin concentration from 14.8 ± 1.0 to 13.9 ± 1.2 g·dl-1 (P < 0.001), it did not increase CBF (974 ± 282 to 872 ± 200 ml·min-1; P = 0.135). We thus conclude that, at least at this moderate altitude, haemoconcentration is not the primary mechanism underlying CBF normalization with acclimatization. These data ostensibly reflect the fact that CBF regulation at high altitude is a complex process that integrates physiological variables beyond CaO2. KEY POINTS: Acute hypoxia causes an increase in cerebral blood flow (CBF). However, as exposure extends, CBF progressively normalizes. We investigated whether hypoxia-induced haemoconcentration contributes to the normalization of CBF during extended hypoxia. Following 4 days of hypobaric hypoxic exposure (corresponding to 3500 m altitude), we measured CBF before and after abolishing hypoxia-induced haemoconcentration by hypervolaemic haemodilution. Contrary to our hypothesis, the haemodilution did not increase CBF in hypoxia. Our findings do not support haemoconcentration as a stimulus for the CBF normalization during extended hypoxia.
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Affiliation(s)
- Rachel Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Institut für Sportwissenschaft, Universität Innsbruck, Tyrol, Austria
| | | | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Joshua C Tremblay
- School of Sport and Health Sciences, Cardiff Metropolitan University, Wales, UK
| | - Johanna Roche
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giulia Roveri
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Justin Lawley
- Institut für Sportwissenschaft, Universität Innsbruck, Tyrol, Austria
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Mazzucco S, Li L, Tuna MA, Rothwell PM. Age-specific sex-differences in cerebral blood flow velocity in relation to haemoglobin levels. Eur Stroke J 2024:23969873241245631. [PMID: 38634499 DOI: 10.1177/23969873241245631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2024] Open
Abstract
INTRODUCTION Cerebral blood flow (CBF) declines with age and abnormalities in CBF are associated with age-related cerebrovascular disease and neurodegeneration. Women have higher CBF than men, although this sex-difference diminishes to some extent with age in healthy subjects. The physiological drivers of these age/sex differences are uncertain, but might be secondary to age and sex-differences in haemoglobin (Hb) level. Hb levels are inversely correlated with CBF, are lower in women, and decline with age in men, but the interrelations between these factors have not been explored systematically either in healthy subjects or across the full age-range in patients with vascular risk factors. We aimed to determine the age-specific interrelations between sex, Hb, and CBF velocity in a large cohort of patients with cerebrovascular disease. PATIENTS AND METHODS In patients with a recent transient ischaemic attack or minor stroke (Oxford Vascular Study) and no ipsilateral or contralateral stenosis of the carotid or intracranial arteries, we related peak-systolic velocity (PSV) and other parameters on transcranial Doppler ultrasound (TCD) of the middle cerebral artery to sex, age, Hb and vascular risk factors. RESULTS Of 958 eligible subjects (mean age/SD = 68.04/14.26, 53.2% male), younger women (age < 55 years) had higher CBF velocities than men (mean sex difference in PSV at age < 55 years = 16.31 cm/s; p < 0.001), but this difference declined with age (interaction p < 0.001), such that it was no longer significant at age 75-84 (∆PSV = 3.26 cm/s; p = 0.12) and was reversed at age ⩾ 85 (∆PSV = -7.42 cm/s; p = 0.05). These changes mirrored trends in levels of Hb, which were higher in men at age < 55 (∆Hb = 1.92 g/dL; p < 0.001), but steadily decreased with age in men but not in women (interaction p < 0.001), with no residual sex-difference at age ⩾ 85 (∆Hb = 0.12 g/dL; p = 0.70). There was an inverse correlation between Hb and PSV in both women and men (both p ⩽ 0.01), and the sex-difference in PSV at age < 55 was substantially diminished after adjustment for Hb (∆PSV = 6.92; p = 0.036; ∆PSV = 5.92, p = 0.13 with further adjustment for end-tidal CO2). In contrast, the sex difference in PSV was unaffected by adjustment for systolic and diastolic blood pressure, heart rate, and vascular risk factors (history of hypertension, diabetes, hyperlipidaemia and smoking). DISCUSSION CBF velocity is strongly correlated with Hb level at all ages, and sex-differences in CBF velocity appear to be explained in major part by age-related sex-differences in Hb.
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Affiliation(s)
- Sara Mazzucco
- Wolfson Centre for Prevention of Stroke and Dementia, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Linxin Li
- Wolfson Centre for Prevention of Stroke and Dementia, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Maria Assuncao Tuna
- Wolfson Centre for Prevention of Stroke and Dementia, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Peter M Rothwell
- Wolfson Centre for Prevention of Stroke and Dementia, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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Roh DJ, Murguia-Fuentes R, Gurel K, Khasiyev F, Rahman S, Bueno PP, Kozii K, Spagnolo-Allende AJ, Cottarelli A, Simonetto M, Ji R, Guo J, Spektor V, Hod EA, Burke DJ, Konofagou E, Rundek T, Wright CB, Marshall RS, Elkind MSV, Gutierrez J. Relationships of Hematocrit With Chronic Covert and Acute Symptomatic Lacunar Ischemic Lesions. Neurology 2024; 102:e207961. [PMID: 38165319 PMCID: PMC10870744 DOI: 10.1212/wnl.0000000000207961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 09/11/2023] [Indexed: 01/03/2024] Open
Abstract
BACKGROUND AND OBJECTIVES Red blood cell (RBC) concentrations are known to associate with ischemic stroke. It is unclear whether RBC concentrations associate specifically with small vessel disease lacunar infarcts. We investigated the hypothesis that RBC concentrations associate with both chronic covert and acute symptomatic brain MRI lacunar infarcts. METHODS A cross-sectional observational analysis was performed across 2 cohorts with available hematocrit (as the assessment of RBC concentration exposure) and MRI outcome data. The primary setting was a population-based cohort of stroke-free, older adult (>50 years) participants from the Northern Manhattan Study (NOMAS) enrolled between 2003 and 2009. A second replication sample consisted of patients admitted with acute stroke and enrolled into the Columbia Stroke Registry (CSR) between 2005 and 2020. Associations of hematocrit with (1) chronic, covert lacunar infarcts and (2) symptomatic (i.e., acute) lacunar strokes were separately assessed from the NOMAS and CSR cohorts, respectively, using general additive models after adjusting for relevant covariates. RESULTS Of 1,218 NOMAS participants analyzed, 6% had chronic, covert lacunar infarcts. The association between hematocrit and these covert lacunar infarcts was U-shaped (χ2 = 9.21 for nonlinear associations; p = 0.03), with people with hematocrit extremes being more likely to have covert lacunar infarcts. Of the 1,489 CSR patients analyzed, 23% had acute lacunar strokes. In this sample, only the relationships of increased hematocrit concentrations and lacunar strokes were replicated (adjusted coefficient β = 0.020; SE = 0.009; p = 0.03). DISCUSSION We identified relationships of hematocrit with MRI lacunar infarcts in both stroke-free and ischemic stroke cohorts, respectively. The relationship between increased hematocrit concentrations with lacunar infarcts was replicated in both cohorts. Further studies are required to clarify the mechanisms behind the relationships of hematocrit with ischemic cerebral small vessel disease.
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Affiliation(s)
- David J Roh
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Ricardo Murguia-Fuentes
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Kursat Gurel
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Farid Khasiyev
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Salwa Rahman
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Pedro Paiva Bueno
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Khrystyna Kozii
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Antonio J Spagnolo-Allende
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Azzurra Cottarelli
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Marialaura Simonetto
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Robin Ji
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Jia Guo
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Vadim Spektor
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Eldad A Hod
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Devin J Burke
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Elisa Konofagou
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Tatjana Rundek
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Clinton B Wright
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Randolph S Marshall
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Mitchell S V Elkind
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
| | - Jose Gutierrez
- From the Departments of Neurology (D.J.R., K.G., S.R., P.P.B., K.K., A.J.S.-A., D.J.B., R.S.M., J. Gutierrez), Pathology and Cell Biology (A.C., E.A.H.), Biomedical Engineering (R.J., E.K.), Psychiatry (J. Guo), and Department of Radiology (V.S.), Vagelos College of Physicians and Surgeons, Columbia University, New York, NY; Department of Neurology (R.M.-F.), Louisiana State University Health Shreveport; Department of Neurology (F.K.), St. Louis University, MO; Department of Neurology (M.S.), Weill Cornell Medical Center, New York, NY; Department of Neurology (T.R.), University of Miami/Jackson Memorial Hospital, FL; National Institute of Neurological Disorders and Stroke (C.B.W.),, Bethesda, MD; and Department of Epidemiology (M.S.V.E.), Mailman School of Public Health, Columbia University, New York, NY
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Hoiland RL, MacLeod DB, Stacey BS, Caldwell HG, Howe CA, Nowak-Flück D, Carr JMJR, Tymko MM, Coombs GB, Patrician A, Tremblay JC, Van Mierlo M, Gasho C, Stembridge M, Sekhon MS, Bailey DM, Ainslie PN. Hemoglobin and cerebral hypoxic vasodilation in humans: Evidence for nitric oxide-dependent and S-nitrosothiol mediated signal transduction. J Cereb Blood Flow Metab 2023; 43:1519-1531. [PMID: 37042194 PMCID: PMC10414015 DOI: 10.1177/0271678x231169579] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 01/20/2023] [Accepted: 03/10/2023] [Indexed: 04/13/2023]
Abstract
Cerebral hypoxic vasodilation is poorly understood in humans, which undermines the development of therapeutics to optimize cerebral oxygen delivery. Across four investigations (total n = 195) we investigated the role of nitric oxide (NO) and hemoglobin-based S-nitrosothiol (RSNO) and nitrite (NO 2 - ) signaling in the regulation of cerebral hypoxic vasodilation. We conducted hemodilution (n = 10) and NO synthase inhibition experiments (n = 11) as well as hemoglobin oxygen desaturation protocols, wherein we measured cerebral blood flow (CBF), intra-arterial blood pressure, and in subsets of participants trans-cerebral release/uptake of RSNO and NO 2 - . Higher CBF during hypoxia was associated with greater trans-cerebral RSNO release but not NO 2 - , while NO synthase inhibition reduced cerebral hypoxic vasodilation. Hemodilution increased the magnitude of cerebral hypoxic vasodilation following acute hemodilution, while in 134 participants tested under normal conditions, hypoxic cerebral vasodilation was inversely correlated to arterial hemoglobin concentration. These studies were replicated in a sample of polycythemic high-altitude native Andeans suffering from excessive erythrocytosis (n = 40), where cerebral hypoxic vasodilation was inversely correlated to hemoglobin concentration, and improved with hemodilution (n = 6). Collectively, our data indicate that cerebral hypoxic vasodilation is partially NO-dependent, associated with trans-cerebral RSNO release, and place hemoglobin-based NO signaling as a central mechanism of cerebral hypoxic vasodilation in humans.
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Affiliation(s)
- Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
- International Collaboration on Repair Discoveries, Vancouver, BC, Canada
| | - David B MacLeod
- Human Pharmacology & Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Hannah G Caldwell
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Connor A Howe
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Daniela Nowak-Flück
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Jay MJR Carr
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Michael M Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Geoff B Coombs
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Alexander Patrician
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Joshua C Tremblay
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Michelle Van Mierlo
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
| | - Chris Gasho
- Department of Medicine, Division of Pulmonary and Critical Care, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Mypinder S Sekhon
- International Collaboration on Repair Discoveries, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, Department of Pathology and Laboratory Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada
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5
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Carr JM, Ainslie PN, MacLeod DB, Tremblay JC, Nowak-Flück D, Howe CA, Stembridge M, Patrician A, Coombs GB, Stacey BS, Bailey DM, Green DJ, Hoiland RL. Cerebral O 2 and CO 2 transport in isovolumic haemodilution: Compensation of cerebral delivery of O 2 and maintenance of cerebrovascular reactivity to CO 2. J Cereb Blood Flow Metab 2023; 43:99-114. [PMID: 36131560 PMCID: PMC9875354 DOI: 10.1177/0271678x221119442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This study investigated the influence of acute reductions in arterial O2 content (CaO2) via isovolumic haemodilution on global cerebral blood flow (gCBF) and cerebrovascular CO2 reactivity (CVR) in 11 healthy males (age; 28 ± 7 years: body mass index; 23 ± 2 kg/m2). Radial artery and internal jugular vein catheters provided measurement of blood pressure and gases, quantification of cerebral metabolism, cerebral CO2 washout, and trans-cerebral nitrite exchange (ozone based chemiluminescence). Prior to and following haemodilution, the partial pressure of arterial CO2 (PaCO2) was elevated with dynamic end-tidal forcing while gCBF was measured with duplex ultrasound. CVR was determined as the slope of the gCBF response and PaCO2. Replacement of ∼20% of blood volume with an equal volume of 5% human serum albumin (Alburex® 5%) reduced haemoglobin (13.8 ± 0.8 vs. 11.3 ± 0.6 g/dL; P < 0.001) and CaO2 (18.9 ± 1.0 vs 15.0 ± 0.8 mL/dL P < 0.001), elevated gCBF (+18 ± 11%; P = 0.002), preserved cerebral oxygen delivery (P = 0.49), and elevated CO2 washout (+11%; P = 0.01). The net cerebral uptake of nitrite (11.6 ± 14.0 nmol/min; P = 0.027) at baseline was abolished following haemodilution (-3.6 ± 17.9 nmol/min; P = 0.54), perhaps underpinning the conservation of CVR (61.7 ± 19.0 vs. 69.0 ± 19.2 mL/min/mmHg; P = 0.23). These findings demonstrate that the cerebrovascular responses to acute anaemia in healthy humans are sufficient to support the maintenance of CVR.
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Affiliation(s)
- Jay Mjr Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - David B MacLeod
- Human Pharmacology & Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Joshua C Tremblay
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Daniela Nowak-Flück
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Alexander Patrician
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7
| | - Geoff B Coombs
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7.,School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Daniel J Green
- School of Human Sciences (Exercise and Sport Sciences), The University of Western Australia, Nedlands, Western Australia
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, School of Health and Exercise Sciences, Kelowna, B.C., Canada, V1V 1V7.,Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.,Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.,International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, British Columbia, Canada
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6
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Powers WJ, An H, Diringer MN. Cerebral Blood Flow and Metabolism. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00003-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Suppan E, Pichler G, Binder-Heschl C, Schwaberger B, Urlesberger B. Three Physiological Components That Influence Regional Cerebral Tissue Oxygen Saturation. Front Pediatr 2022; 10:913223. [PMID: 35769216 PMCID: PMC9234387 DOI: 10.3389/fped.2022.913223] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 05/09/2022] [Indexed: 11/17/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) measurement of regional cerebral tissue oxygen saturation (rcStO2) has become a topic of high interest in neonatology. Multiple studies have demonstrated that rcStO2 measurements are feasible in the delivery room during immediate transition and resuscitation as well as after admission to the neonatal intensive care unit. Reference ranges for different gestational ages, modes of delivery, and devices have already been published. RcStO2 reflects a mixed tissue saturation, composed of arterial (A), venous (V), and capillary signals, derived from small vessels within the measurement compartment. The A:V signal ratio fluctuates based on changes in oxygen delivery and oxygen consumption, which enables a reliable trend monitoring of the balance between these two parameters. While the increasing research evidence supports its use, the interpretation of the absolute values of and trends in rcStO2 is still challenging, which halts its routine use in the delivery room and at the bedside. To visualize the influencing factors and improve the understanding of rcStO2 values, we have created a flowchart, which focuses on the three major physiological components that affect rcStO2: oxygen content, circulation, and oxygen extraction. Each of these has its defining parameters, which are discussed in detail in each section.
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Affiliation(s)
- Ena Suppan
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Gerhard Pichler
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Corinna Binder-Heschl
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Bernhard Schwaberger
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
| | - Berndt Urlesberger
- Division of Neonatology, Department of Pediatrics, Medical University of Graz, Graz, Austria.,Research Unit for Neonatal Micro- and Macrocirculation, Medical University of Graz, Graz, Austria.,Research Unit for Cerebral Development and Oximetry Research, Medical University of Graz, Graz, Austria
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8
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Cote S, Butler R, Michaud V, Lavallee E, Croteau E, Mendrek A, Lepage J, Whittingstall K. The regional effect of serum hormone levels on cerebral blood flow in healthy nonpregnant women. Hum Brain Mapp 2021; 42:5677-5688. [PMID: 34480503 PMCID: PMC8559491 DOI: 10.1002/hbm.25646] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 08/09/2021] [Accepted: 08/20/2021] [Indexed: 12/15/2022] Open
Abstract
Sex hormones estrogen (EST) and progesterone (PROG) have received increased attention for their important physiological action outside of reproduction. While studies have shown that EST and PROG have significant impacts on brain function, their impact on the cerebrovascular system in humans remains largely unknown. To address this, we used a multi-modal magnetic resonance imaging (MRI) approach to investigate the link between serum hormones in the follicular phase and luteal phase of the menstrual cycle (MC) with measures of cerebrovascular function (cerebral blood flow [CBF]) and structure (intracranial artery diameter). Fourteen naturally cycling women were recruited and assessed at two-time points of their MC. CBF was derived from pseudo-continuous arterial spin labeling while diameters of the internal carotid and basilar artery was assessed using time of flight magnetic resonance angiography, blood samples were performed after the MRI. Results show that PROG and EST had opposing and spatially distinct effects on CBF: PROG correlated negatively with CBF in anterior brain regions (r = -.86, p < .01), while EST correlations were positive, yet weak and most prominent in posterior areas (r = .78, p < .01). No significant correlations between either hormone or intracranial artery diameter were observed. These results show that EST and PROG have opposing and regionally distinct effects on CBF and that this relationship is likely not due to interactions with large intracranial arteries. Considering that CBF in healthy women appears tightly linked to their current hormonal state, future studies should consider assessing MC-related hormone fluctuations in the design of functional MRI studies in this population.
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Affiliation(s)
- Samantha Cote
- Faculty of Medicine and Health Sciences, Department of Nuclear Medicine and RadiobiologyUniversity of SherbrookeSherbrookeQuebecCanada
| | - Russell Butler
- Faculty of Arts and Sciences, Department of Computer ScienceBishop's UniversitySherbrookeQuebecCanada
| | - Vincent Michaud
- Department of Diagnostic RadiologyUniversity of SherbrookeSherbrookeQuebecCanada
| | - Eric Lavallee
- Sherbrooke Molecular Imaging Center (CIMS), Sherbrooke University Hospital Research Center (CR‐CHUS)SherbrookeQuebecCanada
| | - Etienne Croteau
- Faculty of Medicine and Health Sciences, Department of Nuclear Medicine and RadiobiologyUniversity of SherbrookeSherbrookeQuebecCanada
- Sherbrooke Molecular Imaging Center (CIMS), Sherbrooke University Hospital Research Center (CR‐CHUS)SherbrookeQuebecCanada
| | - Adrianna Mendrek
- Faculty of Arts and Sciences, Department of PsychologyBishop's UniversitySherbrookeQuebecCanada
| | - Jean‐Francois Lepage
- Faculty of Medicine and Health Sciences, Department of Nuclear Medicine and RadiobiologyUniversity of SherbrookeSherbrookeQuebecCanada
- Faculty of Medicine and Health Sciences, Department of PediatricsUniversity of SherbrookeSherbrookeQuebecCanada
| | - Kevin Whittingstall
- Faculty of Medicine and Health Sciences, Department of Nuclear Medicine and RadiobiologyUniversity of SherbrookeSherbrookeQuebecCanada
- Department of Diagnostic RadiologyUniversity of SherbrookeSherbrookeQuebecCanada
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Ibaraki M, Nakamura K, Matsubara K, Shinohara Y, Kinoshita T. Effect of hematocrit on cerebral blood flow measured by pseudo-continuous arterial spin labeling MRI: A comparative study with 15O-water positron emission tomography. Magn Reson Imaging 2021; 84:58-68. [PMID: 34562565 DOI: 10.1016/j.mri.2021.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 09/16/2021] [Accepted: 09/18/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION In cerebral blood flow (CBF) quantification with pseudo-continuous arterial spin labeling (pCASL) MRI, arterial blood T1 (T1a) is usually fixed to a typical value (e.g., 1650 ms). However, individual T1a depends strongly on hematocrit (Hct) level. To investigate the utility of Hct-based T1a as an alternative to the fixed T1a method, we performed a comparative study with 15O-water positron emission tomography (PET). METHODS For patients with unilateral occlusion or stenosis of major arteries, hemispheric CBF on the healthy side was measured using pCASL and 15O-water PET. The pCASL CBFs were calculated with both (a) fixed T1a (1650 ms) and (b) individual T1a estimated from blood-sampled Hct (Hct-based T1a). Correlation coefficients of Hct-CBF were calculated and compared between pCASL and PET. RESULTS In pCASL, CBF with fixed T1a showed a strong negative correlation with Hct (r = -0.568), which was reduced with individual Hct-based T1a (r = -0.341 to -0.190), consistent with the Hct-CBF relation measured with PET (r = -0.349). DISCUSSION AND CONCLUSION We demonstrated that Hct-based T1a resulted in smaller inter-individual variations in pCASL CBF and an inverse Hct-CBF relationship more similar to that of PET. Care must be taken in the interpretation of pCASL CBF imaging in relation to Hct level even in subjects without anemia. Further comparative studies are needed to investigate whether advanced techniques improve pCASL CBF quantification at the individual level.
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Affiliation(s)
- Masanobu Ibaraki
- Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita, Japan.
| | - Kazuhiro Nakamura
- Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita, Japan.
| | - Keisuke Matsubara
- Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita, Japan.
| | - Yuki Shinohara
- Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita, Japan.
| | - Toshibumi Kinoshita
- Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, Akita, Japan.
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10
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Fernandes IA, Mattos JD, Campos MO, Rocha MP, Mansur DE, Rocha HM, Garcia VP, Alvares T, Secher NH, Nóbrega ACL. Reactive oxygen species play a modulatory role in the hyperventilatory response to poikilocapnic hyperoxia in humans. J Physiol 2021; 599:3993-4007. [PMID: 34245024 DOI: 10.1113/jp281635] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 07/08/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The proposed mechanism for the increased ventilation in response to hyperoxia includes a reduced brain CO2 -[H+ ] washout-induced central chemoreceptor stimulation that results from a decrease in cerebral perfusion and the weakening of the CO2 affinity for haemoglobin. Nonetheless, hyperoxia also results in excessive brain reactive oxygen species (ROS) formation/accumulation, which hypothetically increases central respiratory drive and causes hyperventilation. We then quantified ventilation, cerebral perfusion/metabolism, arterial/internal jugular vein blood gases and oxidant/antioxidant biomarkers in response to hyperoxia during intravenous infusion of saline or ascorbic acid to determine whether excessive ROS production/accumulation contributes to the hyperoxia-induced hyperventilation in humans. Ascorbic acid infusion augmented the antioxidant defence levels, blunted ROS production/accumulation and minimized both the reduction in cerebral perfusion and the increase in ventilation observed during saline infusion. Hyperoxic hyperventilation seems to be mediated by central chemoreceptor stimulation provoked by the interaction between an excessive ROS production/accumulation and reduced brain CO2 -[H+ ] washout. ABSTRACT The hypothetical mechanism for the increase in ventilation ( V ̇ E ) in response to hyperoxia (HX) includes central chemoreceptor stimulation via reduced CO2 -[H+ ] washout. Nonetheless, hyperoxia disturbs redox homeostasis and raises the hypothesis that excessive brain reactive oxygen species (ROS) production/accumulation may increase the sensitivity to CO2 or even solely activate the central chemoreceptors, resulting in hyperventilation. To determine the mechanism behind the HX-evoked increase in V ̇ E , 10 healthy men (24 ± 4 years) underwent 10 min trials of HX under saline and ascorbic acid infusion. V ̇ E , arterial and right internal right jugular vein (ijv) partial pressure for oxygen (PO2 ) and CO2 (PCO2 ), pH, oxidant (8-isoprostane) and antioxidant (ascorbic acid) markers, as well as cerebral blood flow (CBF) (Duplex ultrasonography), were quantified at each hyperoxic trial. HX evoked an increase in arterial partial pressure for oxygen, followed by a hyperventilatory response, a reduction in CBF, an increase in arterial 8-isoprostane, and unchanged PijvCO2 and ijv pH. Intravenous ascorbic acid infusion augmented the arterial antioxidant marker, blunted the increase in arterial 8-isoprostane and attenuated both the reduction in CBF and the HX-induced hyperventilation. Although ascorbic acid infusion resulted in a slight increase in PijvCO2 and a substantial decrease in ijv pH, when compared with the saline bout, HX evoked a similar reduction and a paired increase in the trans-cerebral exchanges for PCO2 and pH, respectively. These findings indicate that the poikilocapnic hyperoxic hyperventilation is likely mediated via the interaction of the acidic brain interstitial fluid and an increase in central chemoreceptor sensitivity to CO2 , which, in turn, seems to be evoked by the excessive ROS production/accumulation.
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Affiliation(s)
- Igor A Fernandes
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
| | - João D Mattos
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
| | - Monique O Campos
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
| | - Marcos P Rocha
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
| | - Daniel E Mansur
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
| | - Helena M Rocha
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
| | - Vinicius P Garcia
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
| | | | - Niels H Secher
- Department of Anaesthesia, Rigshospitalet, Institute for Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Antonio C L Nóbrega
- Laboratory of Exercise Sciences, Fluminense Federal University, Niterói, Brazil
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11
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Taty TM, Mabiala JB, Lovett ME, Pongo J, Musungufu DA, Uchama M, O'Brien NF. Cerebral Blood Flow Velocity is Not Associated with Serum Hemoglobin in Children with Malaria-Associated Anemia. J Neuroimaging 2020; 30:463-467. [PMID: 32449973 DOI: 10.1111/jon.12715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/26/2020] [Accepted: 03/28/2020] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Hemoglobin (Hbg) is often thought to impact cerebral blood flow velocity (CBFV). This study was performed to investigate the relationship between Hbg value and CBFV in African children with malaria. METHODS In this prospective, observational study, children aged 3 months to 18 years with malaria and a normal Blantyre coma score underwent a single transcranial Doppler ultrasound (TCD) examination with a concurrent Hbg check. RESULTS One hundred fifty-six children with a mean age of 43 months were enrolled. Thirty-three children (21%) had severe anemia (Hbg <5g/dL), 46 (29%) had moderate anemia (Hbg 5-6.9 g/dL), 63 children (41%) had mild anemia (7-9.9 g/dL), and 14 children (9%) had no anemia (Hbg >10 g/dL) at the time of TCD examination. Mean averaged CBFV in the middle cerebral artery (MCA) for the cohort was 99% of predicted based on normative values standardized for age. There was no significant correlation between Hbg levels and measured CBFV in the MCA (r = -.09; 95% CI, -.24-.07; P = .29). CONCLUSION In a large sample of African children with malaria, Hbg did not correlate with CBFVs as measured by TCD. Future work that includes baseline TCD measurements and Hbg values as well as other physiological parameters known to influence CBFVs is necessary to confirm these findings.
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Affiliation(s)
- Tshimanga M Taty
- Departement de Pediatrie, Hopital Pediatrique de Kalembe Lembe, Cliniques Universitaires de Kinshasa, Kinshasa, Congo DR
| | - Joseph B Mabiala
- Departement de Pediatrie, Cliniques Universitaires de Kinshasa, Kinshasa, Congo DR
| | - Marlina E Lovett
- Department of Pediatrics, Division of Critical Care Medicine, Nationwide Children's Hospital, The Ohio State University, Columbus, OH
| | - Jean Pongo
- L'Hopital General de Reference de Lodja, Universite des Sciences et des Technologie de Lodja (USTL), Lodja, Sankuru, Congo DR
| | - Davin A Musungufu
- L'Hopital Generale de Reference de Nyankunde, Bukavu, South Kivu, Congo DR
| | - Mananu Uchama
- L'Hopital Generale de Reference de Nyankunde, Bukavu, South Kivu, Congo DR
| | - Nicole F O'Brien
- Department of Pediatrics, Division of Critical Care Medicine, Nationwide Children's Hospital, The Ohio State University, Columbus, OH
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12
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Minhas JS, Rook W, Panerai RB, Hoiland RL, Ainslie PN, Thompson JP, Mistri AK, Robinson TG. Pathophysiological and clinical considerations in the perioperative care of patients with a previous ischaemic stroke: a multidisciplinary narrative review. Br J Anaesth 2020; 124:183-196. [PMID: 31813569 PMCID: PMC7034810 DOI: 10.1016/j.bja.2019.10.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 09/24/2019] [Accepted: 10/18/2019] [Indexed: 12/28/2022] Open
Abstract
With an ageing population and increasing incidence of cerebrovascular disease, an increasing number of patients presenting for routine and emergency surgery have a prior history of stroke. This presents a challenge for pre-, intra-, and postoperative management as the neurological risk is considerably higher. Evidence is lacking around anaesthetic practice for patients with vascular neurological vulnerability. Through understanding the pathophysiological changes that occur after stroke, insight into the susceptibilities of the cerebral vasculature to intrinsic and extrinsic factors can be developed. Increasing understanding of post-stroke systemic and cerebral haemodynamics has provided improved outcomes from stroke and more robust secondary prevention, although this knowledge has yet to be applied to our delivery of anaesthesia in those with prior stroke. This review describes the key pathophysiological and clinical considerations that inform clinicians providing perioperative care for patients with a prior diagnosis of stroke.
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Affiliation(s)
- Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK.
| | - William Rook
- Academic Department of Anaesthesia, Critical Care, Pain, and Resuscitation, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Ryan L Hoiland
- Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Phil N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Jonathan P Thompson
- Anaesthesia and Critical Care, Department of Cardiovascular Sciences, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, UK
| | - Amit K Mistri
- University Hospitals of Leicester NHS Trust, Leicester Royal Infirmary, Leicester, UK
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK; National Institute for Health Research, Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
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13
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Gibbons TD, Tymko MM, Thomas KN, Wilson LC, Stembridge M, Caldwell HG, Howe CA, Hoiland RL, Akerman AP, Dawkins TG, Patrician A, Coombs GB, Gasho C, Stacey BS, Ainslie PN, Cotter JD. Global REACH 2018: The influence of acute and chronic hypoxia on cerebral haemodynamics and related functional outcomes during cold and heat stress. J Physiol 2020; 598:265-284. [PMID: 31696936 DOI: 10.1113/jp278917] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 10/28/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Thermal and hypoxic stress commonly coexist in environmental, occupational and clinical settings, yet how the brain tolerates these multi-stressor environments is unknown Core cooling by 1.0°C reduced cerebral blood flow (CBF) by 20-30% and cerebral oxygen delivery (CDO2 ) by 12-19% at sea level and high altitude, whereas core heating by 1.5°C did not reliably reduce CBF or CDO2 Oxygen content in arterial blood was fully restored with acclimatisation to 4330 m, but concurrent cold stress reduced CBF and CDO2 Gross indices of cognition were not impaired by any combination of thermal and hypoxic stress despite large reductions in CDO2 Chronic hypoxia renders the brain susceptible to large reductions in oxygen delivery with concurrent cold stress, which might make monitoring core temperature more important in this context ABSTRACT: Real-world settings are composed of multiple environmental stressors, yet the majority of research in environmental physiology investigates these stressors in isolation. The brain is central in both behavioural and physiological responses to threatening stimuli and, given its tight metabolic and haemodynamic requirements, is particularly susceptible to environmental stress. We measured cerebral blood flow (CBF, duplex ultrasound), cerebral oxygen delivery (CDO2 ), oesophageal temperature, and arterial blood gases during exposure to three commonly experienced environmental stressors - heat, cold and hypoxia - in isolation, and in combination. Twelve healthy male subjects (27 ± 11 years) underwent core cooling by 1.0°C and core heating by 1.5°C in randomised order at sea level; acute hypoxia ( P ET , O 2 = 50 mm Hg) was imposed at baseline and at each thermal extreme. Core cooling and heating protocols were repeated after 16 ± 4 days residing at 4330 m to investigate any interactions with high altitude acclimatisation. Cold stress decreased CBF by 20-30% and CDO2 by 12-19% (both P < 0.01) irrespective of altitude, whereas heating did not reliably change either CBF or CDO2 (both P > 0.08). The increases in CBF with acute hypoxia during thermal stress were appropriate to maintain CDO2 at normothermic, normoxic values. Reaction time was faster and slower by 6-9% with heating and cooling, respectively (both P < 0.01), but central (brain) processes were not impaired by any combination of environmental stressors. These findings highlight the powerful influence of core cooling in reducing CDO2 . Despite these large reductions in CDO2 with cold stress, gross indices of cognition remained stable.
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Affiliation(s)
- T D Gibbons
- School of Physical Education, Sport & Exercise Science, University of Otago, 55/47 Union St W, Dunedin, 9016, New Zealand
| | - M M Tymko
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - K N Thomas
- Department of Surgical Sciences, University of Otago, 201 Great King St, Dunedin, 9016, New Zealand
| | - L C Wilson
- Department of Medicine, University of Otago, 201 Great King St, Dunedin, 9016, New Zealand
| | - M Stembridge
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK
| | - H G Caldwell
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - C A Howe
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - R L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - A P Akerman
- Faculty of Health Sciences, University of Ottawa, 125 University St, Ottawa, Ontario, Canada, K1N 6N5
| | - T G Dawkins
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK
| | - A Patrician
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - G B Coombs
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - C Gasho
- Division of Pulmonary, Critical Care, Hyperbaric and Sleep Medicine, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - B S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
| | - P N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - J D Cotter
- School of Physical Education, Sport & Exercise Science, University of Otago, 55/47 Union St W, Dunedin, 9016, New Zealand
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14
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Howe CA, Ainslie PN, Tremblay JC, Carter HH, Patrician A, Stembridge M, Williams A, Drane AL, Delorme E, Rieger MG, Tymko MM, Gasho C, Santoro A, MacLeod DB, Hoiland RL. UBC-Nepal Expedition: Haemoconcentration underlies the reductions in cerebral blood flow observed during acclimatization to high altitude. Exp Physiol 2019; 104:1963-1972. [PMID: 31410899 DOI: 10.1113/ep087663] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 08/13/2019] [Indexed: 12/16/2022]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to evaluate the degree to which increases in haematocrit alter cerebral blood flow and cerebral oxygen delivery during acclimatization to high altitude. What is the main finding and its importance? Through haemodilution, we determined that, after 1 week of acclimatization, the primary mechanism contributing to the cerebral blood flow response during acclimatization is an increase in haemoglobin and haematocrit. The remaining contribution to the cerebral blood flow response during acclimatization is likely to be attributable to ventilatory acclimatization. ABSTRACT At high altitude, an increase in haematocrit (Hct) is achieved through altitude-induced diuresis and erythropoiesis, both of which result in increased arterial oxygen content. Given the impact of alterations in Hct on oxygen content, haemoconcentration has been hypothesized to mediate, in part, the attenuation of the initial elevation in cerebral blood flow (CBF) at high altitude. To test this hypothesis, healthy men (n = 13) ascended to 5050 m over 9 days without the aid of prophylactic acclimatization medications. After 1 week of acclimatization at 5050 m, participants were haemodiluted by rapid saline infusion (2.10 ± 0.28 l) to return Hct towards pre-acclimatization values. Arterial blood gases, Hct, global CBF (duplex ultrasound) and haemodynamic variables were measured after initial arrival at 5050 m and after 1 week of acclimatization at high altitude, before and after the haemodilution protocol. After 1 week at 5050 m, the Hct increased from 42.5 ± 2.5 to 49.6 ± 2.5% (P < 0.001), and it was subsequently reduced to 45.6 ± 2.3% (P < 0.001) after haemodilution. Global CBF decreased from 844 ± 160 to 619 ± 136 ml min-1 (P = 0.033) after 1 week of acclimatization and increased to 714 ± 204 ml min -1 (P = 0.045) after haemodilution. Despite the significant changes in Hct, and thus oxygen content, cerebral oxygen delivery was unchanged at all time points. Furthermore, these observations occurred in the absence of any changes in mean arterial blood pressure, cardiac output, arterial blood pH or oxygen saturation pre- and posthaemodilution. These data highlight the influence of Hct in the regulation of CBF and are the first to demonstrate experimentally that haemoconcentration contributes to the reduction in CBF during acclimatization to altitude.
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Affiliation(s)
- Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Joshua C Tremblay
- Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Howard H Carter
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Alex Patrician
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Mike Stembridge
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, UK
| | - Alex Williams
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Aimee L Drane
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, UK
| | - Eric Delorme
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Mathew G Rieger
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Chris Gasho
- VA Loma Linda Healthcare System and Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Antoinette Santoro
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - David B MacLeod
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
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15
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Stotesbury H, Kawadler JM, Hales PW, Saunders DE, Clark CA, Kirkham FJ. Vascular Instability and Neurological Morbidity in Sickle Cell Disease: An Integrative Framework. Front Neurol 2019; 10:871. [PMID: 31474929 PMCID: PMC6705232 DOI: 10.3389/fneur.2019.00871] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/26/2019] [Indexed: 12/20/2022] Open
Abstract
It is well-established that patients with sickle cell disease (SCD) are at substantial risk of neurological complications, including overt and silent stroke, microstructural injury, and cognitive difficulties. Yet the underlying mechanisms remain poorly understood, partly because findings have largely been considered in isolation. Here, we review mechanistic pathways for which there is accumulating evidence and propose an integrative systems-biology framework for understanding neurological risk. Drawing upon work from other vascular beds in SCD, as well as the wider stroke literature, we propose that macro-circulatory hyper-perfusion, regions of relative micro-circulatory hypo-perfusion, and an exhaustion of cerebral reserve mechanisms, together lead to a state of cerebral vascular instability. We suggest that in this state, tissue oxygen supply is fragile and easily perturbed by changes in clinical condition, with the potential for stroke and/or microstructural injury if metabolic demand exceeds tissue oxygenation. This framework brings together recent developments in the field, highlights outstanding questions, and offers a first step toward a linking pathophysiological explanation of neurological risk that may help inform future screening and treatment strategies.
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Affiliation(s)
- Hanne Stotesbury
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Jamie M Kawadler
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Patrick W Hales
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Dawn E Saunders
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom.,Department of Radiology, Great Ormond Hospital, London, United Kingdom
| | - Christopher A Clark
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom
| | - Fenella J Kirkham
- Developmental Neurosciences, UCL Great Ormond Institute of Child Health, London, United Kingdom.,Clinical and Experimental Sciences, University of Southampton, Southampton, United Kingdom.,Department of Child Health, University Hospital Southampton, Southampton, United Kingdom.,Department of Paediatric Neurology, Kings College Hospital NHS Foundation Trust, London, United Kingdom
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16
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Hoiland RL, Fisher JA, Ainslie PN. Regulation of the Cerebral Circulation by Arterial Carbon Dioxide. Compr Physiol 2019; 9:1101-1154. [DOI: 10.1002/cphy.c180021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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17
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Chai Y, Bush AM, Coloigner J, Nederveen AJ, Tamrazi B, Vu C, Choi S, Coates TD, Lepore N, Wood JC. White matter has impaired resting oxygen delivery in sickle cell patients. Am J Hematol 2019; 94:467-474. [PMID: 30697803 PMCID: PMC6874897 DOI: 10.1002/ajh.25423] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/27/2018] [Accepted: 01/22/2019] [Indexed: 12/13/2022]
Abstract
Although modern medical management has lowered overt stroke occurrence in patients with sickle cell disease (SCD), progressive white matter (WM) damage remains common. It is known that cerebral blood flow (CBF) increases to compensate for anemia, but sufficiency of cerebral oxygen delivery, especially in the WM, has not been systematically investigated. Cerebral perfusion was measured by arterial spin labeling in 32 SCD patients (age range: 10-42 years old, 14 males, 7 with HbSC, 25 HbSS) and 25 age and race-matched healthy controls (age range: 15-45 years old, 10 males, 12 with HbAS, 13 HbAA); 8/24 SCD patients were receiving regular blood transfusions and 14/24 non-transfused SCD patients were taking hydroxyurea. Imaging data from control subjects were used to calculate maps for CBF and oxygen delivery in SCD patients and their T-score maps. Whole brain CBF was increased in SCD patients with a mean T-score of 0.5 and correlated with lactate dehydrogenase (r2 = 0.58, P < 0.0001). When corrected for oxygen content and arterial saturation, whole brain and gray matter (GM) oxygen delivery were normal in SCD, but WM oxygen delivery was 35% lower than in controls. Age and hematocrit were the strongest predictors for WM CBF and oxygen delivery in patients with SCD. There was spatial co-localization between regions of low oxygen delivery and WM hyperintensities on T2 FLAIR imaging. To conclude, oxygen delivery is preserved in the GM of SCD patients, but is decreased throughout the WM, particularly in areas prone to WM silent strokes.
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Affiliation(s)
- Yaqiong Chai
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
| | - Adam M. Bush
- Department of Radiology, Stanford, University, California
| | - Julie Coloigner
- Univ Rennes, CNRS, Inria, Inserm, IRISA UMR 6074, VISAGES - ERL U 1228, Rennes, France
| | - Aart J. Nederveen
- Department of Radiology and Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Benita Tamrazi
- Department of Radiology and Nuclear Medicine, Children’s Hospital Los Angeles,Los Angeles, California
| | - Chau Vu
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, California
| | - Thomas D. Coates
- Section of Hematology, Children’s Hospital Los Angeles, Los Angeles, California
| | - Natasha Lepore
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
- Department of Radiology and Nuclear Medicine, Children’s Hospital Los Angeles,Los Angeles, California
| | - John C. Wood
- Department of Biomedical Engineering, University of Southern California Engineering, School, Los Angeles, California
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, California
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18
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19
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Clement P, Mutsaerts HJ, Václavů L, Ghariq E, Pizzini FB, Smits M, Acou M, Jovicich J, Vanninen R, Kononen M, Wiest R, Rostrup E, Bastos-Leite AJ, Larsson EM, Achten E. Variability of physiological brain perfusion in healthy subjects - A systematic review of modifiers. Considerations for multi-center ASL studies. J Cereb Blood Flow Metab 2018; 38:1418-1437. [PMID: 28393659 PMCID: PMC6120130 DOI: 10.1177/0271678x17702156] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Quantitative measurements of brain perfusion are influenced by perfusion-modifiers. Standardization of measurement conditions and correction for important modifiers is essential to improve accuracy and to facilitate the interpretation of perfusion-derived parameters. An extensive literature search was carried out for factors influencing quantitative measurements of perfusion in the human brain unrelated to medication use. A total of 58 perfusion modifiers were categorized into four groups. Several factors (e.g., caffeine, aging, and blood gases) were found to induce a considerable effect on brain perfusion that was consistent across different studies; for other factors, the modifying effect was found to be debatable, due to contradictory results or lack of evidence. Using the results of this review, we propose a standard operating procedure, based on practices already implemented in several research centers. Also, a theory of 'deep MRI physiotyping' is inferred from the combined knowledge of factors influencing brain perfusion as a strategy to reduce variance by taking both personal information and the presence or absence of perfusion modifiers into account. We hypothesize that this will allow to personalize the concept of normality, as well as to reach more rigorous and earlier diagnoses of brain disorders.
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Affiliation(s)
- Patricia Clement
- 1 Department of Radiology and nuclear medicine, Ghent University, Ghent, Belgium
| | - Henk-Jan Mutsaerts
- 2 Cognitive Neurology Research Unit, Sunnybrook Healthy Sciences Centre, Toronto, Canada.,3 Academic Medical Center, Amsterdam, the Netherlands
| | - Lena Václavů
- 3 Academic Medical Center, Amsterdam, the Netherlands
| | - Eidrees Ghariq
- 4 Leiden University Medical Center, Leiden, the Netherlands
| | | | | | - Marjan Acou
- 1 Department of Radiology and nuclear medicine, Ghent University, Ghent, Belgium
| | - Jorge Jovicich
- 7 Magnetic Resonance Imaging Laboratory Center for Mind/Brain Sciences, University of Trento, Mattarello, Italy
| | | | | | | | - Egill Rostrup
- 10 Department of Diagnostics, Glostrup Hospital, University of Copenhagen, Denmark
| | | | | | - Eric Achten
- 1 Department of Radiology and nuclear medicine, Ghent University, Ghent, Belgium
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20
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Bush AM, Borzage MT, Choi S, Václavů L, Tamrazi B, Nederveen AJ, Coates TD, Wood JC. Determinants of resting cerebral blood flow in sickle cell disease. Am J Hematol 2016; 91:912-7. [PMID: 27263497 DOI: 10.1002/ajh.24441] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 11/11/2022]
Abstract
Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated. This study examined the physiological determinants of CBF in 37 patients with sickle cell disease, 38 ethnicity matched control subjects and 16 patients with anemia of non-sickle origin. Cerebral blood flow was measured using phase contrast MRI of the carotid and vertebral arteries. CBF increased inversely to oxygen content (r(2) = 0.69, P < 0.0001). Brain oxygen delivery, the product of CBF and oxygen content, was normal in all groups. Brain composition, specifically the relative amounts of grey and white matter, was the next strongest CBF predictor, presumably by influencing cerebral metabolic rate. Grey matter/white matter ratio and CBF declined monotonically until the age of 25 in all subjects, consistent with known maturational changes in brain composition. Further CBF reductions were observed with age in subjects older than 35 years of age, likely reflecting microvascular aging. On multivariate regression, CBF was independent of disease state, hemoglobin S, hemoglobin F, reticulocyte count and cell free hemoglobin, suggesting that it is regulated similarly in patients and control subjects. In conclusion, sickle cell disease patients had sufficient oxygen delivery at rest, but accomplish this only by marked increases in their resting CBF, potentially limiting their ability to further augment flow in response to stress. Am. J. Hematol. 91:912-917, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Adam M. Bush
- Department of Biomedical Engineering; University of Southern California; California
| | - Matthew T. Borzage
- Division of Neonatology and Radiology; Children's Hospital Los Angeles; California
| | - Soyoung Choi
- Neurosciences Program; University of Southern California; California
| | - Lena Václavů
- Department of Radiology; Academic Medical Center; Amsterdam
| | - Benita Tamrazi
- Department of Radiology; Children's Hospital Los Angeles; California
| | | | - Thomas D. Coates
- Section of Hematology; Children's Hospital Los Angeles; California
| | - John C. Wood
- Department of Radiology; Children's Hospital Los Angeles; California
- Division of Cardiology; Children's Hospital Los Angeles; California
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21
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Affiliation(s)
- Donald S. Prough
- Department of Anesthesia Bowman Gray School of Medicine 300 South Hawthorne Rd Winston-Salem, NC 2 7103
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22
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Furukawa K, Abumiya T, Sakai K, Hirano M, Osanai T, Shichinohe H, Nakayama N, Kazumata K, Aida T, Houkin K. Measurement of human blood viscosity by an electromagnetic spinning sphere viscometer. J Med Eng Technol 2016; 40:285-92. [DOI: 10.1080/03091902.2016.1181216] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Koji Furukawa
- Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Takeo Abumiya
- Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Keiji Sakai
- Department of Fundamental Engineering, Institute of Industrial Science, University of Tokyo, Tokyo, Japan
| | - Miki Hirano
- Department of Fundamental Engineering, Institute of Industrial Science, University of Tokyo, Tokyo, Japan
| | - Toshiya Osanai
- Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Hideo Shichinohe
- Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Naoki Nakayama
- Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Ken Kazumata
- Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | | | - Kiyohiro Houkin
- Department of Neurosurgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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23
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Borzage MT, Bush AM, Choi S, Nederveen AJ, Václavů L, Coates TD, Wood JC. Predictors of cerebral blood flow in patients with and without anemia. J Appl Physiol (1985) 2016; 120:976-81. [PMID: 26796758 PMCID: PMC4835904 DOI: 10.1152/japplphysiol.00994.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 01/19/2016] [Indexed: 11/22/2022] Open
Abstract
Sickle cell disease (SCD) is the most common cause of stroke in childhood and results primarily from a mismatch of cerebral oxygen supply and demand rather than arterial obstruction. However, resting cerebral blood flow (CBF) has not been examined in the general African American population, in whom obesity, hypertension, cerebrovascular disease, and diminished cerebrovascular reserve capacity are common. To better understand the underlying physiological substrate upon which SCD is superimposed, we measured CBF in 32 young (age 28 ± 10 yr), asymptomatic African American subjects with and without sickle cell trait (n= 14). To characterize the effects of chronic anemia, in isolation of sickle hemoglobin we also studied a cohort of 13 subjects with thalassemia major (n= 10), dyserythropoetic anemia (n= 1), or spherocytosis (n= 2). Blood was analyzed for complete blood count, hemoglobin electrophoresis, cell free hemoglobin, and lactate dehydrogenase. Multivariate regression analysis showed that oxygen content was the strongest predictor of CBF (r(2)= 0.33,P< 0.001). CBF declined rapidly in the second and third decades of life, but this drop was explained by reductions in cerebral gray matter. However, age effects persisted after correction for brain composition, possibly representing microvascular impairment. CBF was independent of viscosity, hemoglobin S%, and body mass index. Hyperoxia resulted in reduced CBF by 12.6% (P= 0.0002), and CBF changes were proportional to baseline oxygen content (r(2)= 0.16,P= 0.02). These data suggest that these hemoglobin subtypes do not alter the normal CBF regulation of the balance of oxygen supply and demand.
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Affiliation(s)
- Matthew T Borzage
- Division of Neonatology and Radiology, Children's Hospital Los Angeles, Los Angeles, California
| | - Adam M Bush
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California
| | - Aart J Nederveen
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Lena Václavů
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Thomas D Coates
- Division of Hematology, Children's Hospital Los Angeles, Los Angeles, California; and
| | - John C Wood
- Division of Cardiology and Radiology, Children's Hospital Los Angeles, Los Angeles, California
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24
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Ameriso SF, Meiselman HJ, Saraj A, Fisher M. The Effect of Hemorheologic Factors on Middle Cerebral Artery Blood Flow Velocity in Young Individuals. J Neuroimaging 2016; 2:16-8. [DOI: 10.1111/jon19922116] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/1990] [Revised: 06/10/1991] [Accepted: 07/22/1991] [Indexed: 11/29/2022] Open
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25
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Cerebral Blood Flow and Metabolism. Stroke 2016. [DOI: 10.1016/b978-0-323-29544-4.00003-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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26
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Hoiland RL, Bain AR, Rieger MG, Bailey DM, Ainslie PN. Hypoxemia, oxygen content, and the regulation of cerebral blood flow. Am J Physiol Regul Integr Comp Physiol 2015; 310:R398-413. [PMID: 26676248 DOI: 10.1152/ajpregu.00270.2015] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 11/30/2015] [Indexed: 01/13/2023]
Abstract
This review highlights the influence of oxygen (O2) availability on cerebral blood flow (CBF). Evidence for reductions in O2 content (CaO2 ) rather than arterial O2 tension (PaO2 ) as the chief regulator of cerebral vasodilation, with deoxyhemoglobin as the primary O2 sensor and upstream response effector, is discussed. We review in vitro and in vivo data to summarize the molecular mechanisms underpinning CBF responses during changes in CaO2 . We surmise that 1) during hypoxemic hypoxia in healthy humans (e.g., conditions of acute and chronic exposure to normobaric and hypobaric hypoxia), elevations in CBF compensate for reductions in CaO2 and thus maintain cerebral O2 delivery; 2) evidence from studies implementing iso- and hypervolumic hemodilution, anemia, and polycythemia indicate that CaO2 has an independent influence on CBF; however, the increase in CBF does not fully compensate for the lower CaO2 during hemodilution, and delivery is reduced; and 3) the mechanisms underpinning CBF regulation during changes in O2 content are multifactorial, involving deoxyhemoglobin-mediated release of nitric oxide metabolites and ATP, deoxyhemoglobin nitrite reductase activity, and the downstream interplay of several vasoactive factors including adenosine and epoxyeicosatrienoic acids. The emerging picture supports the role of deoxyhemoglobin (associated with changes in CaO2 ) as the primary biological regulator of CBF. The mechanisms for vasodilation therefore appear more robust during hypoxemic hypoxia than during changes in CaO2 via hemodilution. Clinical implications (e.g., disorders associated with anemia and polycythemia) and future study directions are considered.
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Affiliation(s)
- Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, British Columbia, Canada; and
| | - Anthony R Bain
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, British Columbia, Canada; and
| | - Mathew G Rieger
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, British Columbia, Canada; and
| | - Damian M Bailey
- Neurovascular Research Laboratory, Research Institute of Science and Health, University of South Wales, Glamorgan, United Kingdom
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, British Columbia, Canada; and Neurovascular Research Laboratory, Research Institute of Science and Health, University of South Wales, Glamorgan, United Kingdom
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Sedaghat S, Vernooij MW, Loehrer E, Mattace-Raso FUS, Hofman A, van der Lugt A, Franco OH, Dehghan A, Ikram MA. Kidney Function and Cerebral Blood Flow: The Rotterdam Study. J Am Soc Nephrol 2015; 27:715-21. [PMID: 26251352 DOI: 10.1681/asn.2014111118] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 05/12/2015] [Indexed: 12/21/2022] Open
Abstract
CKD is linked with various brain disorders. Whereas brain integrity is dependent on cerebral perfusion, the association between kidney function and cerebral blood flow has yet to be determined. This study was performed in the framework of the population-based Rotterdam Study and included 2645 participants with mean age of 56.6 years (45% men). We used eGFR and albumin-to-creatinine ratio to assess kidney function and performed phase-contrast magnetic resonance imaging of basilar and carotid arteries to measure cerebral blood flow. Participants had an average (SD) eGFR of 86.3 (13.4) ml/min per 1.73 m(2) and a median (interquartile range) albumin-to-creatinine ratio of 3.4 (2.2-6.1) mg/g. In age- and sex-adjusted models, a higher albumin-to-creatinine ratio was associated with lower cerebral blood flow level (difference in cerebral blood flow [milliliters per minute per 100 ml] per doubling of the albumin-to-creatinine ratio, -0.31; 95% confidence interval, -0.58 to -0.03). The association was not present after adjustment for cardiovascular risk factors (P=0.10). Each 1 SD lower eGFR was associated with 0.42 ml/min per 100 ml lower cerebral blood flow (95% confidence interval, 0.01 to 0.83) adjusted for cardiovascular risk factors. Thus, in this population-based study, we observed that lower eGFR is independently associated with lower cerebral blood flow.
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Affiliation(s)
| | | | | | - Francesco U S Mattace-Raso
- Division of Geriatric Medicine, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | | | | | | | - M Arfan Ikram
- Departments of Epidemiology, Radiology, and Neurology and
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Yamal JM, Rubin ML, Benoit JS, Tilley BC, Gopinath S, Hannay HJ, Doshi P, Aisiku IP, Robertson CS. Effect of Hemoglobin Transfusion Threshold on Cerebral Hemodynamics and Oxygenation. J Neurotrauma 2015; 32:1239-45. [PMID: 25566694 DOI: 10.1089/neu.2014.3752] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Cerebral dysfunction caused by traumatic brain injury may adversely affect cerebral hemodynamics and oxygenation leading to worse outcomes if oxygen capacity is decreased due to anemia. In a randomized clinical trial of 200 patients comparing transfusion thresholds <7 g/dl versus 10 g/dl, where transfusion of leukoreduced packed red blood cells was used to maintain the assigned hemoglobin threshold, no long-term neurological difference was detected. The current study examines secondary outcome measures of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and brain tissue oxygenation (PbtO2) in patients enrolled in this randomized clinical trial. We observed a lower hazard for death (hazard ratio [HR]=0.12, 95% confidence interval [CI]=0.02-0.99) during the first 3 days post-injury, and a higher hazard for death after three days (HR=2.55, 95% CI=1.00-6.53) in the 10 g/dl threshold group as compared to the 7 g/dL threshold group. No significant differences were observed for ICP and CPP but MAP was slightly lower in the 7 g/dL group, although the decreased MAP did not result in increased hypotension. Overall brain tissue hypoxia events were not significantly different in the two transfusion threshold groups. When the PbtO2 catheter was placed in normal brain, however, tissue hypoxia occurred in 25% of patients in the 7 g/dL threshold group, compared to 10.2% of patients in the 10 g/dL threshold group (p=0.04). Although we observed a few differences in hemodynamic outcomes between the transfusion threshold groups, none were of major clinical significance and did not affect long-term neurological outcome and mortality.
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Affiliation(s)
- Jose-Miguel Yamal
- 1 Department of Biostatistics, University of Texas School of Public Health , Houston, Texas
| | - M Laura Rubin
- 1 Department of Biostatistics, University of Texas School of Public Health , Houston, Texas
| | - Julia S Benoit
- 2 Department of Basic Vision Sciences, College of Optometry and Texas Institute for Measurement Evaluation and Statistics, University of Houston , Houston, Texas
| | - Barbara C Tilley
- 1 Department of Biostatistics, University of Texas School of Public Health , Houston, Texas
| | - Shankar Gopinath
- 3 Department of Neurosurgery, Baylor College of Medicine , Houston, Texas
| | - H Julia Hannay
- 4 Department of Psychology, University of Houston , Houston, Texas
| | - Pratik Doshi
- 5 Department of Emergency Medicine and Internal Medicine, University of Texas Health Science Center at Houston , Houston, Texas
| | - Imoigele P Aisiku
- 6 Department of Emergency Medicine, Brigham and Women's Hospital , Boston, Massachusetts
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van der Veen PH, Muller M, Vincken KL, Westerink J, Mali WPTM, van der Graaf Y, Geerlings MI. Hemoglobin, hematocrit, and changes in cerebral blood flow: the Second Manifestations of ARTerial disease-Magnetic Resonance study. Neurobiol Aging 2014; 36:1417-23. [PMID: 25618615 DOI: 10.1016/j.neurobiolaging.2014.12.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 12/07/2014] [Accepted: 12/15/2014] [Indexed: 11/26/2022]
Abstract
Hemoglobin and hematocrit are important determinants of blood viscosity and arterial oxygen content and may therefore influence cerebral blood flow (CBF). We examined cross-sectional and prospective associations of hemoglobin and hematocrit with CBF in 569 patients with manifest arterial disease (mean age 57 ± 10 years) with available data on magnetic resonance angiography to measure parenchymal CBF. Mean (SD) parenchymal CBF at baseline was 52.3 (9.8) mL/min/100 mL and decreased with 1.5 (11.0) mL/min/100 mL after on average 3.9 years of follow-up. Linear regression analyses showed that greater hemoglobin and hematocrit values were associated with lower baseline parenchymal CBF and more decline in parenchymal CBF over time, independent of cardiovascular risk factors, use of antiplatelet drugs, anticoagulants, or diuretics, and brain measures: adjusted mean differences (95% confidence interval [CI]) in decline in parenchymal CBF between patients in the lower and upper quartiles of hemoglobin and hematocrit were -2.48 (95% CI -3.70 to -1.25) and -3.69 (95% CI -5.45 to -1.94) mL/min/100 mL. Higher hemoglobin and hematocrit were associated with lower baseline parenchymal CBF and a greater decline in parenchymal CBF over time, possibly as a result of physiological compensating mechanisms.
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Affiliation(s)
- Pieternella H van der Veen
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands; Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Majon Muller
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands; Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands
| | - Koen L Vincken
- Image Sciences Institute, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Jan Westerink
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Willem P T M Mali
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Yolanda van der Graaf
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Mirjam I Geerlings
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
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Effects of alcohol intoxication and gender on cerebral perfusion: an arterial spin labeling study. Alcohol 2011; 45:725-37. [PMID: 21621371 DOI: 10.1016/j.alcohol.2011.04.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/15/2011] [Accepted: 04/15/2011] [Indexed: 12/16/2022]
Abstract
An increasing number of studies use functional MRI (fMRI) and blood oxygen level-dependent (BOLD) signal to investigate the neurofunctional basis of acute alcohol effects on the brain. However, the BOLD signal reflects neural activity only indirectly as it depends on regional hemodynamic changes and is therefore sensitive to vasoactive substances, such as alcohol. We used MRI-based pulsed arterial spin labeling (ASL) method to quantify effects of acute intoxication on resting cerebral perfusion. Gender effects have not been previously examined and yet they are of particular interest given the differences in hormonal dynamics, alcohol metabolism, and hemodynamic regulation. Nineteen young, healthy individuals (nine women) with no personal or familial alcohol- or drug-related problems served as their own controls by participating in both alcohol (0.6g/kg ethanol for men, 0.55g/kg for women) and placebo scanning sessions in a counterbalanced manner. Regionally specific effects of the moderate alcohol dose on gray matter perfusion were examined with voxel-wise and region-of-interest analyses suggesting an interaction between gender and alcohol beverage. Acute intoxication increased perfusion in bilateral frontal regions in men but not in women. Under placebo, stronger cortical perfusion was observed in women compared with men primarily in the left hemisphere in frontal, parietal, and temporal areas. These results emphasize gender differences and regional specificity of alcohol's effects of cerebral perfusion possibly because of interactive influences on hormonal, metabolic, and hemodynamic autoregulatory systems. Alcohol-induced perfusion increase correlated positively with impulsivity/antisocial tendencies, consistent with dopaminergic mediation of reward, and its effects on cortical perfusion. Additional ASL studies are needed to investigate dose- and time-dependent effects of alcohol intoxication and gender on the hemodynamic factors that conjointly influence BOLD signal to disambiguate the vascular/metabolic mechanisms from the neurally based changes.
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Ibaraki M, Shinohara Y, Nakamura K, Miura S, Kinoshita F, Kinoshita T. Interindividual variations of cerebral blood flow, oxygen delivery, and metabolism in relation to hemoglobin concentration measured by positron emission tomography in humans. J Cereb Blood Flow Metab 2010; 30:1296-305. [PMID: 20160738 PMCID: PMC2949226 DOI: 10.1038/jcbfm.2010.13] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Regional cerebral blood flow (CBF) and oxygen metabolism can be measured by positron emission tomography (PET) with (15)O-labeled compounds. Hemoglobin (Hb) concentration of blood, a primary determinant of arterial oxygen content (C(a)O(2)), influences cerebral circulation. We investigated interindividual variations of CBF, cerebral blood volume (CBV), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO(2)) in relation to Hb concentration in healthy human volunteers (n=17) and in patients with unilateral steno-occlusive disease (n=44). For the patients, data obtained only from the contralateral hemisphere (normal side) were analyzed. The CBF and OEF were inversely correlated with Hb concentration, but CMRO(2) was independent of Hb concentration. Oxygen delivery defined as a product of C(a)O(2) and CBF (C(a)O(2) CBF) increased with a rise of Hb concentration. The analysis with a simple oxygen model showed that oxygen diffusion parameter (L) was constant over the range of Hb concentration, indicating that a homeostatic mechanism controlling CBF is necessary to maintain CMRO(2). The current findings provide important knowledge to understand the control mechanism of cerebral circulation and to interpret the (15)O PET data in clinical practice.
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Affiliation(s)
- Masanobu Ibaraki
- Department of Radiology and Nuclear Medicine, Akita Research Institute of Brain and Blood Vessels, 6-10 Senshu-Kubota Machi, Akita, Japan.
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Wajima D, Nakamura M, Horiuchi K, Miyake H, Takeshima Y, Tamura K, Motoyama Y, Konishi N, Nakase H. Enhanced cerebral ischemic lesions after two-vein occlusion in diabetic rats. Brain Res 2010; 1309:126-35. [DOI: 10.1016/j.brainres.2009.10.061] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2009] [Revised: 10/22/2009] [Accepted: 10/24/2009] [Indexed: 11/26/2022]
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Abstract
Investigation of the interplay between the cerebral circulation and brain cellular function is fundamental to understanding both the pathophysiology and treatment of stroke. Currently, PET is the only technique that provides accurate, quantitative in vivo regional measurements of both cerebral circulation and cellular metabolism in human subjects. We review normal human cerebral blood flow and metabolism and human PET studies of ischemic stroke, carotid artery disease, vascular dementia, intracerebral hemorrhage and aneurysmal subarachnoid hemorrhage and discuss how these studies have added to our understanding of the pathophysiology of human cerebrovascular disease.
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Affiliation(s)
- William J. Powers
- Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Allyson R. Zazulia
- Departments of Neurology and Radiology, Washington University School of Medicine, St. Louis, MO
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Ainslie PN, Ogoh S. Regulation of cerebral blood flow in mammals during chronic hypoxia: a matter of balance. Exp Physiol 2009; 95:251-62. [PMID: 19617269 DOI: 10.1113/expphysiol.2008.045575] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Respiratory-induced changes in the partial pressures of arterial carbon dioxide (PaCO2) and oxygen (PaO2) play a major role in cerebral blood flow (CBF) regulation. Elevations in PaCO2 (hypercapnia) lead to vasodilatation and increases in CBF, whereas reductions in PaCO2 (hypocapnia) lead to vasoconstriction and decreases in CBF. A fall in PaO2 (hypoxia) below a certain threshold (<40-45 mmHg) also produces cerebral vasodilatation. Upon initial exposure to hypoxia, CBF is elevated via a greater relative degree of hypoxia compared with hypocapnia. At this point, hypoxia-induced elevations in blood pressure and loss of cerebral autoregulation, stimulation of neuronal pathways, angiogenesis, release of adenosine, endothelium-derived NO and a variety of autocoids and cytokines are additional factors acting to increase CBF. Following 2-3 days, however, the process of ventilatory acclimatization results in a progressive rise in ventilation, which increases PaO2 and reduces PaCO2, collectively acting to attenuate the initial rise in CBF. Other factors acting to lower CBF include elevations in haematocrit, sympathetic nerve activity and local and endothelium-derived vasoconstrictors. Hypoxia-induced alterations of cerebrovascular reactivity, autoregulation and pulmonary vascular tone may also affect CBF. Thus, the extent of change in CBF during exposure to hypoxia is dependent on the balance between the myriad of vasodilators and constrictors derived from the endothelium, neuronal innervations and perfusion pressure. This review examines the extent and mechanisms by which hypoxia regulates CBF. Particular focus will be given to the marked influence of hypoxia associated with exposure to high altitude and chronic lung disease. The associated implications of these hypoxia-induced integrative alterations for the regulation of CBF are discussed, and future avenues for research are proposed.
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Affiliation(s)
- Philip N Ainslie
- Department of Human Kinetics, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna V1V 1V7, Canada.
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36
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Hillbom ME. What supports the role of alcohol as a risk factor for stroke? ACTA MEDICA SCANDINAVICA. SUPPLEMENTUM 2009; 717:93-106. [PMID: 3314365 DOI: 10.1111/j.0954-6820.1987.tb13046.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
For more than 30 years, clinical observations to link alcohol abuse and stroke have accumulated in several countries. Studies of general populations have indicated that the risk for stroke increases with increasing alcohol consumption. Studies of young victims of stroke where the classical risk factors of stroke are uncommon, have demonstrated that even occasional heavy drinking carries an increased risk for stroke. In particular, the increased occurrence of strokes during weekends, the very time of heavy alcohol consumption in non-alcoholics, supports this notion. Alcoholics seem to get their strokes at an earlier age than non-alcoholics. Paradoxically, the published evidence has implicated drinking in both ischemic and hemorrhagic strokes, which suggests that there may be more than one mechanism by which alcohol can increase the risk. Strokes seem to be precipitated during the alcohol intoxication itself rather than the following withdrawal syndrome, but the contributing mechanisms, except for bleedings caused by external violence, are unknown. Alcohol can produce fluctuations in platelet reactivity and untoward interactions with certain drugs, but it remains to be demonstrated that such effects are temporally related to the onset of ischemic and hemorrhagic strokes.
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Affiliation(s)
- M E Hillbom
- Department of Clinical and Experimental Alcohol and Drug Addiction Research, Karolinska Hospital, Stockholm, Sweden
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Frietsch T, Maurer MH, Vogel J, Gassmann M, Kuschinsky W, Waschke KF. Reduced cerebral blood flow but elevated cerebral glucose metabolic rate in erythropoietin overexpressing transgenic mice with excessive erythrocytosis. J Cereb Blood Flow Metab 2007; 27:469-76. [PMID: 16804549 DOI: 10.1038/sj.jcbfm.9600360] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To examine the impact of excessive erythrocytosis on local cerebral blood flow (CBF) and cerebral glucose metabolic rate (CMR(glc)), we made use of our constitutively erythropoietin (Epo)-overexpressing transgenic mouse line (tg-6) that reach a mean hematocrit of 0.87. Compared with wild-type (wt) control siblings, CBF decreased by 44% in tg-6 mice, while upon hemodilution (tg-6-HD) to a physiologic hematocrit (e.g., 0.44) tg-6-HD mice returned the CBF to wt levels. Cerebral blood flow was determined in another transgenic mouse line that overexpresses human Epo in the brain only (tg-21): CBF increased by 17% compared with wt controls. However, oxygen delivery was similar in all four mouse groups tested (wt, tg-6, tg-6-HD and tg-21). Mean CMR(glc) was higher in tg-6 (+72%), tg-6-HD mice (+43%) and tg-21 (+22%) than in wt mice. Local CMR(glc) was higher in all 40 brain regions in tg-6 but only in 15 and 8 regions in tg-6-HD and tg-21 mice. These results show that prolonged increases in hematocrit did not alter cerebral oxygen delivery at a decreased CBF and increased CMR(glc). Hemodilution suggests that high blood viscosity is a cause of the decrease in CBF and partly of the increase in CMR(glc). Cerebral glucose metabolic rate may also be increased by a direct effect of Epo in the brain (tg-21 mice).
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Affiliation(s)
- Thomas Frietsch
- Department of Anesthesiology and Critical Care Medicine, Faculty of Clinical Medicine Mannheim, Mannheim, Germany.
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Platt D, Horn J, Summa JD, Schmitt-Rüth R, Kauntz J, Krönert E. On the efficacy of piracetam in geriatric patients with acute cerebral ischemia: a clinically controlled double-blind study. Arch Gerontol Geriatr 2005; 16:149-64. [PMID: 15374345 DOI: 10.1016/0167-4943(93)90006-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/1992] [Revised: 02/08/1993] [Accepted: 02/09/1993] [Indexed: 11/21/2022]
Abstract
Using a randomized, double blind group comparison, the efficacy and tolerance of piracetam as an additional therapy of hydroxyethyl starch, venous infusion and low dose heparin treatment, which are the basis of therapy in our hospital, has been studied in patients displaying acute cerebral ischemia. A total of 56 patients were enrolled, of whom 27 were given piracetam and 29 served as a control during a 28-day period. Using single photon emission computer tomography (SPECT) analysis, we observed that in 23 piracetam-treated patients (85.2%) a reduction in the area of brain regions displaying an impaired flow rate occurred (P < 0.001; Fisher's exact two-sided test). Only six of placebo-treated patients (20.7%) showed an improved flow rate. Analysis of the recorded computer tomography map gave an improvement coefficient >2 (flow rate marginally or better improved) for 23 piracetam patients as compared with 5 placebo patients (P < 0.001, Uleman test).
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Affiliation(s)
- D Platt
- University of Erlangen-Nürnberg, Germany
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Kazmierski R, Guzik P, Ambrosius W, Ciesielska A, Moskal J, Kozubski W. Predictive value of white blood cell count on admission for in-hospital mortality in acute stroke patients. Clin Neurol Neurosurg 2004; 107:38-43. [PMID: 15567551 DOI: 10.1016/j.clineuro.2004.03.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2003] [Revised: 03/03/2004] [Accepted: 03/18/2004] [Indexed: 11/21/2022]
Abstract
OBJECTIVE In the present study, we sought to determine the predictive value of white blood cell (WBC) count measured on admission for in-hospital death in acute stroke patients. METHODS WBC count was measured automatically in 400 consecutive acute stroke patients (67.5 +/- 12.9 years old; 226 female) on admission to hospital. Patients included into the study had symptoms starting less than 12 h prior to hospitalization and no known causes of inflammation. Logistic regression adjusted for age, gender, the presence of diabetes, hypertension, atrial fibrillation, previous stroke and ischemic heart disease was used for the calculation of odds ratio (OR) with 95% confidence interval (CI) for in-hospital mortality. RESULTS Stroke patients with WBC counts in the third tertile (over 9.7 x 10(3) microL(-1)) had more than eight times (OR: 8.26; 95% CI: 3.95-17.25; P < 0.0001) increased risk of in-hospital mortality as compared with the rest of the patients. The WBC count increment of every 1000 cell/microL was associated with OR for in-hospital death of 1.27 (95% CI: 1.17-1.39; P < 0.0001). There was also a significant correlation between patients' WBC count and their clinical condition and degree of disability at the time of admission to hospital. CONCLUSION An increased WBC count within the first 12 h of onset of an ischemic stroke is a strong prognostic factor for in-hospital mortality.
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Affiliation(s)
- Radoslaw Kazmierski
- Department of Neurology, University of Medical Sciences, Przybyszewskiego 49, PL 60-355 Poznañ, Poland.
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Abstract
Children with sickle disease are at high risk for ischemic stroke and transient ischemic attacks, usually secondary to intracranial arteriopathy involving the terminal internal carotid and proximal middle cerebral and anterior cerebral arteries, which may be diagnosed using transcranial Doppler ultrasound or magnetic resonance angiography (MRA). Other central nervous system (CNS) complications include seizures and coma, which may be secondary to ischemic stroke, sinovenous thrombosis, reversible posterior leukoencephalopathy, or acute demyelination. The immediate priority after an acute CNS event is to improve cerebral oxygenation with oxygen supplementation to maintain peripheral saturation measured using pulse oximetry between 96% and 99%, and a simple transfusion of packed cells within an hour of presentation if the patient's hemoglobin is less than 10 g/dL. The patient then should have erythrocytapheresis or manual exchange to reduce the hemoglobin S percentage to below 30%. Computed tomography to exclude hemorrhage is mandatory and MR T2-weighted imaging with MRA, fat-saturated imaging of the neck (dissection), MR venography (sinovenous thrombosis), and diffusion-weighted imaging usually distinguishes between arterial ischemic stroke and the differential diagnoses. Comatose patients with widespread focal or global cerebral edema may have good functional outcome after surgical decompression. Anticoagulation may be indicated for dissection or sinovenous thrombosis and steroids for demyelination. Blood pressure should be reduced slowly if raised in patients with reversible posterior leukoencephalopathy. Seizures should be treated aggressively and electroencephalogram monitoring should be done to exclude subclinical seizures if the patient is unconscious. Hemorrhagic stroke may require craniectomy and drainage and/or management of vasospasm. Interventional neuroradiology with coils is an alternative to surgical clipping for aneurysms. For secondary prevention, regular blood transfusion to hemoglobin S of less than 30% reduces the risk of recurrent stroke from approximately 67% to approximately 10%. Hydroxyurea and phlebotomy may be used in patients who are alloimmunized. Moyamoya syndrome is a risk factor for recurrence despite prophylactic blood transfusion. Revascularization may prevent additional stroke. Bone marrow transplantation may be offered to patients with human leukocyte antigen-compatible siblings. Blood transfusion prevents stroke in patients with velocities greater than 200 cm per second on TCD; a phase III trial studying the prevention of the progression of silent infarction is being done. Emerging primary prophylaxis regimens being tested include citrulline and arginine, aspirin, and overnight oxygen supplementation. Physicians caring for children with sickle cell disease also should ensure adequate nutrition, including five servings of fruit and vegetables a day. The role of vitamin supplementation is controversial, particularly when patients must take daily penicillin prophylaxis.
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Affiliation(s)
- Fenella J. Kirkham
- Department of Pediatrics, Washington University School of Medicine, 4444 Forest Park Boulevard, St. Louis, MO 63108, USA.
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Zazulia AR, Markham J, Powers WJ. Cerebral Blood Flow and Metabolism in Human Cerebrovascular Disease. Stroke 2004. [DOI: 10.1016/b0-44-306600-0/50047-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Affiliation(s)
- Jerry L Spivak
- Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Bedell E, Prough DS. Anesthetic management of traumatic brain injury. ANESTHESIOLOGY CLINICS OF NORTH AMERICA 2002; 20:417-39. [PMID: 12166003 DOI: 10.1016/s0889-8537(01)00010-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The management of TBI remains an important and frustrating component of the practice of anesthesiology and critical care medicine. The difficulties in management of TBI as well as the poor response rates to medical therapy after TBI are not new. The following passage appeared in the introductory chapter of a text on TBI from 1897: "The manner of treatment is of importance in only a minority of cases, since many subjects of intracranial injury are fated to die whatever measures may be adopted for their relief, and a still greater number are destined to recover though left entirely to the resources of nature. It is probable that in by far the larger proportion of cases in which the issue is determined by treatment it is met in the initial stage, and by insuring restoration from primary shock" [111]. Although secondary insults from factors such as hypotension, hypoxemia, and hyperventilation increase morbidity and mortality, data are not yet available to indicate whether scrupulous prevention and prompt treatment of secondary injuries will reduce morbidity and mortality. In addition, no specific intervention to date has improved overall long-term outcome. With ongoing research, perhaps active interventions will become available. Until that time, thoughtful and careful attention to physiologic management provides the greatest opportunity for a good outcome.
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Affiliation(s)
- Eric Bedell
- Department of Anesthesiology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555-0591, USA.
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Mariak Z, Krejza J, Swiercz M, Kordecki K, Lewko J. Accuracy of transcranial color Doppler ultrasonography in the diagnosis of middle cerebral artery spasm determined by receiver operating characteristic analysis. J Neurosurg 2002; 96:323-30. [PMID: 11838807 DOI: 10.3171/jns.2002.96.2.0323] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The value of transcranial Doppler ultrasonography for the detection of middle cerebral artery (MCA) spasm has been asserted. None of the published studies, however, has adequately scrutinized the overall diagnostic accuracy of this procedure. There are only sporadic reports concerning the utility of transcranial color Doppler (TCCD) ultrasonography, although this method has been proved to be more precise. In this study the authors attempted to estimate the performance of TCCD ultrasonography in detecting MCA narrowing by using receiver operating characteristic (ROC) curve analysis, based on TCCD studies obtained in a relatively large, randomly selected population of patients. METHODS Transcranial color Doppler ultrasonography studies were obtained in 100 consecutive patients (54 men and 46 women ages 18-74 years, median age 50 years) routinely referred by neurosurgeons for intraarterial angiography. The M1 segment of the MCA was insonated using a 2.5-MHz probe via a temporal acoustic window, and angle-corrected flow velocities were obtained. Angiographically depicted vasospasm was graded as none, mild (< or = 25% vessel caliber reduction), and moderate to severe (> 25% vessel caliber reduction). The effectiveness of TCCD ultrasonography in diagnosing MCA spasm was evaluated by calculating the areas under the ROC curves (Az). Of the 200 MCAs examined, 173 were successfully visualized with the aid of TCCD ultrasonography. Mild vasospasm was angiographically diagnosed in 15 arteries and moderate-to-severe vasospasm in 28. The best-performing TCCD parameter for the detection of MCA narrowing was revealed to be peak systolic velocity. The Az value for moderate-to-severe vasospasm only was 0.93 and that for all vasospasms was 0.8. The best efficiency, that is, the optimal tradeoff between sensitivity and specificity in diagnosing vasospasms, was associated with a peak systolic velocity of 182 cm/second. CONCLUSIONS The performance of TCCD ultrasonography in the diagnosis of advanced MCA narrowing is very good, and is acceptable for all vasospasms. The best-performing parameter was peak systolic velocity.
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Affiliation(s)
- Zenon Mariak
- Department of Neurosurgery, Bialystok Medical Academy, Poland
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Rebel A, Lenz C, Krieter H, Waschke KF, Van Ackern K, Kuschinsky W. Oxygen delivery at high blood viscosity and decreased arterial oxygen content to brains of conscious rats. Am J Physiol Heart Circ Physiol 2001; 280:H2591-7. [PMID: 11356614 DOI: 10.1152/ajpheart.2001.280.6.h2591] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We addressed the question to which extent cerebral blood flow (CBF) is maintained when, in addition to a high blood viscosity (Bvis) arterial oxygen content (CaO2 ) is gradually decreased. CaO2 was decreased by hemodilution to hematocrits (Hct) of 30, 22, 19, and 15% in two groups. One group received blood replacement (BR) only and served as the control. The second group received an additional high viscosity solution of polyvinylpyrrolidone (BR/PVP). Bvis was reduced in the BR group and was doubled in the BR/PVP. Despite different Bvis, CBF did not differ between BR and BR/PVP rats at Hct values of 30 and 22%, indicating a complete vascular compensation of the increased Bvis at decreased CaO2 . At an Hct of 19%, local cerebral blood flow (LCBF) in some brain structures was lower in BR/PVP rats than in BR rats. At the lowest Hct of 15%, LCBF of 15 brain structures and mean CBF were reduced in BR/PVP. The resulting decrease in cerebral oxygen delivery in the BR/PVP group indicates a global loss of vascular compensation. We concluded that vasodilating mechanisms compensated for Bvis increases thereby maintaining constant cerebral oxygen delivery. Compensatory mechanisms were exhausted at a Hct of 19% and lower as indicated by the reduction of CBF and cerebral oxygen delivery.
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Affiliation(s)
- A Rebel
- Faculty of Clinical Medicine, Department of Anesthesiology, Mannheim D-68067, Heidelberg, Germany.
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Meade TW. Design and intermediate results of the Lower Extremity Arterial Disease Event Reduction (LEADER)* trial of bezafibrate in men with lower extremity arterial disease [ISRCTN4119421]. CURRENT CONTROLLED TRIALS IN CARDIOVASCULAR MEDICINE 2001; 2:195-204. [PMID: 11806795 PMCID: PMC57751 DOI: 10.1186/cvm-2-4-195] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2001] [Revised: 06/25/2001] [Accepted: 06/27/2001] [Indexed: 11/30/2022]
Abstract
BACKGROUND: Raised levels of both triglycerides and fibrinogen, each of which are reduced by bezafibrate, may contribute to lower extremity arterial disease (LEAD). This condition is characterized by a particularly high incidence of coronary heart disease (CHD) and stroke, but is little studied thus far in randomised controlled trials. METHOD: Patients were recruited through 85 practices in the British Medical Research Council General Practice Research Framework and through nine hospital vascular clinics. The treatment regimen, which is double-blind and placebo-controlled, is bezafibrate 400 mg/day. The 1568 patients recruited represent 86% of those eligible at screening. RESULTS: None of the anticipated side effects (mainly gastrointestinal) differed between the two groups. Nearly 80% of the total person-years accrued at 3 years were spent on trial treatment. Bezafibrate significantly reduced total cholesterol by approximately 8.0% and low-density lipoprotein (LDL)-cholesterol by approximately 9.0%, and increased high-density lipoprotein (HDL)-cholesterol by approximately 11.0% initially, falling to about 6.0% at 3 years. Triglycerides were significantly reduced by about 23.0% and fibrinogen by about 14.0%. Plasma creatinine rose by approximately 11% in those on active treatment. All of these effects were highly significant (P < 0.0001). Bezafibrate had no effect on the level of C-reactive protein (CRP). CONCLUSION: The trial recruited an unusually high proportion of eligible patients, ensuring the general applicability of its results. The fibrinogen-lowering and lipid-modifying effects of bezafibrate were confirmed. Although bezafibrate lowers fibrinogen, it has no effect on CRP; this suggests that the reduction in fibrinogen is due to an effect on its metabolism rather than suppression of an inflammatory response.
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Affiliation(s)
- Thomas W Meade
- MRC Epidemiology and Medical Care Unit, Wolfson Institute of Preventive Medicine, London, UK.
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Krejza J, Mariak Z, Huba M, Wolczynski S, Lewko J. Effect of endogenous estrogen on blood flow through carotid arteries. Stroke 2001; 32:30-6. [PMID: 11136910 DOI: 10.1161/01.str.32.1.30] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Recent evidence suggests that physiological changes in the concentration of endogenous estrogens may influence stroke outcome. The purpose of this study was to determine a menstrual cycle-related profile of blood flow through the carotid arteries and its correlation with estrogen concentration. METHODS The flow velocity and cross-sectional area of the common carotid artery, internal carotid artery (ICA), and external carotid artery (ECA) were measured with duplex Doppler sonography throughout the menstrual cycle in 14 healthy women. Concentration of plasma 17beta-estradiol, progesterone, hematocrit, hemoglobin, and blood pressure were also determined. RESULTS In the follicular phase, the concentration of estrogen increased to reach a peak on day 14, whereas concentration of progesterone remained low. The mean and end-diastolic velocities in the ICA increased on average by 15% of their base values, along with increasing concentrations of estrogen (r=0.59 and 0.65, respectively). The profile of flow velocity changes in this artery corresponded to the profile of estrogen concentration. In contrast to the ICA, flow velocities in the ECA decreased from their base value, reaching their minimum in the luteal phase. The mean flow velocity in the common carotid artery increased on day 14 by just 2% of its base value. The lumen of the carotid arteries was stable throughout the cycle. Hematocrit, hemoglobin, and systolic blood pressure also remained unchanged. CONCLUSIONS Increased concentration of endogenous estrogen correlates with substantial augmentation of flow in the internal carotid artery. This promotion of flow is caused mainly by decreased cerebrovascular resistance with consequent "stealing" of blood from the ECA.
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Affiliation(s)
- J Krejza
- Department of Radiology, Bialystok Medical Academy, Bialystok, Poland.
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Abstract
We hypothesized that the response of cerebral blood flow (CBF) to changing viscosity would be dependent on "baseline" CBF, with a greater influence of viscosity during high-flow conditions. Plasma viscosity was adjusted to 1.0 or 3.0 cP in rats by exchange transfusion with red blood cells diluted in lactated Ringer solution or with dextran. Cortical CBF was measured by H(2) clearance. Two groups of animals remained normoxic and normocarbic and served as controls. Other groups were made anemic, hypercapnic, or hypoxic to increase CBF. Under baseline conditions before intervention, CBF did not differ between groups and averaged 49.4 +/- 10.2 ml. 100 g(-1). min(-1) (+/-SD). In control animals, changing plasma viscosity to 1. 0 or 3.0 cP resulted in CBF of 55.9 +/- 8.6 and 42.5 +/- 12.7 ml. 100 g(-1). min(-1), respectively (not significant). During hemodilution, hypercapnia, and hypoxia with a plasma viscosity of 1. 0 cP, CBF varied from 98 to 115 ml. 100 g(-1). min(-1). When plasma viscosity was 3.0 cP during hemodilution, hypercapnia, and hypoxia, CBF ranged from 56 to 58 ml. 100 g(-1). min(-1) and was significantly reduced in each case (P < 0.05). These results support the hypothesis that viscosity has a greater role in regulation of CBF when CBF is increased. In addition, because CBF more closely followed changes in plasma viscosity (rather than whole blood viscosity), we believe that plasma viscosity may be the more important factor in controlling CBF.
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Affiliation(s)
- Y Tomiyama
- Department of Anesthesia, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA
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Solerte SB, Ceresini G, Ferrari E, Fioravanti M. Hemorheological changes and overproduction of cytokines from immune cells in mild to moderate dementia of the Alzheimer's type: adverse effects on cerebromicrovascular system. Neurobiol Aging 2000; 21:271-81. [PMID: 10867211 DOI: 10.1016/s0197-4580(00)00105-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An association between hemorheological alterations (i.e., whole-blood and plasma hyperviscosity, reduced erythrocyte deformability, increased red cell aggregation, hyperfibrinogenemia and increased acute-phase protein levels) and the mild stage of senile dementia of the Alzheimer's type (DAT) was suggested in the present study. In particular, hyperfibrinogenemia and the increase of erytrhocyte aggregation were correlated with the increased generation and release of TNF-alpha and IFN-gamma (spontaneous release and IL-2-modulated release) from natural killer (NK) lymphocytes (CD16+, CD56+, CD3- cells) of patients with DAT; whereas a normal cytokine release from NK cells was found in healthy old subjects and in patients with vascular dementia (VaD). The in vitro and in vivo administration of the hemorheologic drug pentoxifylline (PTX) significantly reduced spontaneous and IL-2-modulated cytokine overproduction from NK cells (in vitro effects with 500 U/ml and 1000 U/ml/NK cells) and improved all the hemorheological parameters. Taken together, these data suggest that disturbances of cerebrovascular flow and of hemorheology could be considered a negative component related to the pathogenesis and progression of DAT neurodegeneration. The association between hemorheological changes and alterations of TNF-alpha and IFN-gamma release from NK may indicate a potential immunorheologic mechanism associated with cerebrovascular damage in DAT and could suggest the use of vascular protective drugs as support of the main pharmacological and non-pharmacological therapy of AD.
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Affiliation(s)
- S B Solerte
- Department of Internal Medicine, Geriatrics and Gerontology Clinic, School of Geriatrics, University of Pavia, Ospedale S.Margherita, Piazza Borromeo 2, 27100, Pavia, Italy.
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