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Cerebral blood flow response to acute hypoxic hypoxia

Hypoxic hypoxia (inspiratory hypoxia) stimulates an increase in cerebral blood flow (CBF) maintaining oxygen delivery to the brain. However, this response, particularly at the tissue level, is not well characterised. This study quantifies the CBF response to acute hypoxic hypoxia in healthy subjects...

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Autores principales: Harris, Ashley D, Murphy, Kevin, Diaz, Claris M, Saxena, Neeraj, Hall, Judith E, Liu, Thomas T, Wise, Richard G
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BlackWell Publishing Ltd 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4114548/
https://www.ncbi.nlm.nih.gov/pubmed/24123253
http://dx.doi.org/10.1002/nbm.3026
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author Harris, Ashley D
Murphy, Kevin
Diaz, Claris M
Saxena, Neeraj
Hall, Judith E
Liu, Thomas T
Wise, Richard G
author_facet Harris, Ashley D
Murphy, Kevin
Diaz, Claris M
Saxena, Neeraj
Hall, Judith E
Liu, Thomas T
Wise, Richard G
author_sort Harris, Ashley D
collection PubMed
description Hypoxic hypoxia (inspiratory hypoxia) stimulates an increase in cerebral blood flow (CBF) maintaining oxygen delivery to the brain. However, this response, particularly at the tissue level, is not well characterised. This study quantifies the CBF response to acute hypoxic hypoxia in healthy subjects. A 20-min hypoxic (mean P(ET)o(2) = 52 mmHg) challenge was induced and controlled by dynamic end-tidal forcing whilst CBF was measured using pulsed arterial spin labelling perfusion MRI. The rate constant, temporal delay and magnitude of the CBF response were characterised using an exponential model for whole-brain and regional grey matter. Grey matter CBF increased from 76.1 mL/100 g/min (95% confidence interval (CI) of fitting: 75.5 mL/100 g/min, 76.7 mL/100 g/min) to 87.8 mL/100 g/min (95% CI: 86.7 mL/100 g/min, 89.6 mL/100 g/min) during hypoxia, and the temporal delay and rate constant for the response to hypoxia were 185 s (95% CI: 132 s, 230 s) and 0.0035 s(–1) (95% CI: 0.0019 s(–1), 0.0046 s(–1)), respectively. Recovery from hypoxia was faster with a delay of 20 s (95% CI: –38 s, 38 s) and a rate constant of 0.0069 s(–1) (95% CI: 0.0020 s(–1), 0.0103 s(–1)). R(2)*, an index of blood oxygenation obtained simultaneously with the CBF measurement, increased from 30.33 s(–1) (CI: 30.31 s(–1), 30.34 s(–1)) to 31.48 s(–1) (CI: 31.47 s(–1), 31.49 s(–1)) with hypoxia. The delay and rate constant for changes in R(2)* were 24 s (95% CI: 21 s, 26 s) and 0.0392 s(–1) (95% CI: 0.0333 s(–1), 0.045 s(–1) ), respectively, for the hypoxic response, and 12 s (95% CI: 10 s, 13 s) and 0.0921 s(–1) (95% CI: 0.0744 s(–1), 0.1098 s(–1)/) during the return to normoxia, confirming rapid changes in blood oxygenation with the end-tidal forcing system. CBF and R(2)* reactivity to hypoxia differed between subjects, but only R(2)* reactivity to hypoxia differed significantly between brain regions. © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.
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spelling pubmed-41145482014-09-02 Cerebral blood flow response to acute hypoxic hypoxia Harris, Ashley D Murphy, Kevin Diaz, Claris M Saxena, Neeraj Hall, Judith E Liu, Thomas T Wise, Richard G NMR Biomed Research Articles Hypoxic hypoxia (inspiratory hypoxia) stimulates an increase in cerebral blood flow (CBF) maintaining oxygen delivery to the brain. However, this response, particularly at the tissue level, is not well characterised. This study quantifies the CBF response to acute hypoxic hypoxia in healthy subjects. A 20-min hypoxic (mean P(ET)o(2) = 52 mmHg) challenge was induced and controlled by dynamic end-tidal forcing whilst CBF was measured using pulsed arterial spin labelling perfusion MRI. The rate constant, temporal delay and magnitude of the CBF response were characterised using an exponential model for whole-brain and regional grey matter. Grey matter CBF increased from 76.1 mL/100 g/min (95% confidence interval (CI) of fitting: 75.5 mL/100 g/min, 76.7 mL/100 g/min) to 87.8 mL/100 g/min (95% CI: 86.7 mL/100 g/min, 89.6 mL/100 g/min) during hypoxia, and the temporal delay and rate constant for the response to hypoxia were 185 s (95% CI: 132 s, 230 s) and 0.0035 s(–1) (95% CI: 0.0019 s(–1), 0.0046 s(–1)), respectively. Recovery from hypoxia was faster with a delay of 20 s (95% CI: –38 s, 38 s) and a rate constant of 0.0069 s(–1) (95% CI: 0.0020 s(–1), 0.0103 s(–1)). R(2)*, an index of blood oxygenation obtained simultaneously with the CBF measurement, increased from 30.33 s(–1) (CI: 30.31 s(–1), 30.34 s(–1)) to 31.48 s(–1) (CI: 31.47 s(–1), 31.49 s(–1)) with hypoxia. The delay and rate constant for changes in R(2)* were 24 s (95% CI: 21 s, 26 s) and 0.0392 s(–1) (95% CI: 0.0333 s(–1), 0.045 s(–1) ), respectively, for the hypoxic response, and 12 s (95% CI: 10 s, 13 s) and 0.0921 s(–1) (95% CI: 0.0744 s(–1), 0.1098 s(–1)/) during the return to normoxia, confirming rapid changes in blood oxygenation with the end-tidal forcing system. CBF and R(2)* reactivity to hypoxia differed between subjects, but only R(2)* reactivity to hypoxia differed significantly between brain regions. © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd. BlackWell Publishing Ltd 2013-12 2013-10-07 /pmc/articles/PMC4114548/ /pubmed/24123253 http://dx.doi.org/10.1002/nbm.3026 Text en © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd. http://creativecommons.org/licenses/by/3.0/ This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research Articles
Harris, Ashley D
Murphy, Kevin
Diaz, Claris M
Saxena, Neeraj
Hall, Judith E
Liu, Thomas T
Wise, Richard G
Cerebral blood flow response to acute hypoxic hypoxia
title Cerebral blood flow response to acute hypoxic hypoxia
title_full Cerebral blood flow response to acute hypoxic hypoxia
title_fullStr Cerebral blood flow response to acute hypoxic hypoxia
title_full_unstemmed Cerebral blood flow response to acute hypoxic hypoxia
title_short Cerebral blood flow response to acute hypoxic hypoxia
title_sort cerebral blood flow response to acute hypoxic hypoxia
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4114548/
https://www.ncbi.nlm.nih.gov/pubmed/24123253
http://dx.doi.org/10.1002/nbm.3026
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