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Cerebral artery dilatation maintains cerebral oxygenation at extreme altitude and in acute hypoxia--an ultrasound and MRI study

Wilson, MH; Edsell, MEG; Davagnanam, I; Hirani, SP; Martin, DS; Levett, DZH; Thornton, JS; ... Imray, CHE; + view all (2011) Cerebral artery dilatation maintains cerebral oxygenation at extreme altitude and in acute hypoxia--an ultrasound and MRI study. Journal of Cerebral Blood Flow and Metabolism , 31 (10) pp. 2019-2029. 10.1038/jcbfm.2011.81. Green open access

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Abstract

Transcranial Doppler is a widely used noninvasive technique for assessing cerebral artery blood flow. All previous high altitude studies assessing cerebral blood flow (CBF) in the field that have used Doppler to measure arterial blood velocity have assumed vessel diameter to not alter. Here, we report two studies that demonstrate this is not the case. First, we report the highest recorded study of CBF (7,950 m on Everest) and demonstrate that above 5,300 m, middle cerebral artery (MCA) diameter increases (n = 24 at 5,300 m, 14 at 6,400 m, and 5 at 7,950 m). Mean MCA diameter at sea level was 5.30 mm, at 5,300 m was 5.23 mm, at 6,400 m was 6.66 mm, and at 7,950 m was 9.34 mm (P < 0.001 for change between 5,300 and 7,950 m). The dilatation at 7,950 m reversed with oxygen. Second, we confirm this dilatation by demonstrating the same effect (and correlating it with ultrasound) during hypoxia (FiO(2) = 12% for 3 hours) in a 3-T magnetic resonance imaging study at sea level (n = 7). From these results, we conclude that it cannot be assumed that cerebral artery diameter is constant, especially during alterations of inspired oxygen partial pressure, and that transcranial 2D ultrasound is a technique that can be used at the bedside or in the remote setting to assess MCA caliber. Journal of Cerebral Blood Flow & Metabolism (2011) 31, 2019-2029; doi:10.1038/jcbfm.2011.81; published online 8 June 2011

Type: Article
Title: Cerebral artery dilatation maintains cerebral oxygenation at extreme altitude and in acute hypoxia--an ultrasound and MRI study
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/jcbfm.2011.81
Publisher version: http://dx.doi.org/10.1038/jcbfm.2011.81
Language: English
Additional information: This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivative Works 3.0 Unported License (CC BY-NC-ND). To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/
Keywords: brain imaging, cerebral blood flow, high altitude, MRI, transcranial Doppler, blood-flow-velocity, acute mountain-sickness, Transcranial Doppler sonography, magnetic-resonance angiography, cerebrovascular responses, hemodynamic-response, everest, humans, acclimatization, autoregulation
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Brain Repair and Rehabilitation
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Department of Neuromuscular Diseases
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Internal Medicine
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci > Department of Surgical Biotechnology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health
URI: https://discovery.ucl.ac.uk/id/eprint/1312106
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