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

Wilson, Mark H., Edsell, Mark E.G., Davagnanam, Indran, Hirani, Shashivadan P., Martin, Dan S., Levett, Denny Z.H., Thornton, John S., Golay, Xavier, Strycharczuk, Lisa, Newman, Stanton P., Montgomery, Hugh E., Grocott, Mike P.W. and Imray, Christopher H.E. Caudwell Xtreme Everest Research Group (2011) Cerebral artery dilatation maintains cerebral oxygenation at extreme altitude and in acute hypoxia--an ultrasound and MRI study Journal of Cerebral Blood Flow & Metabolism, 31, (10), pp. 2019-2029. (doi:10.1038/jcbfm.2011.81). (PMID:21654697).

Record type: Article


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

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Published date: October 2011
Organisations: Human Development & Health


Local EPrints ID: 348884
ISSN: 0271-678X
PURE UUID: f05205a8-ea82-45b3-bd67-17a9814d56d8

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Date deposited: 21 Feb 2013 14:31
Last modified: 18 Jul 2017 04:46

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Author: Mark H. Wilson
Author: Mark E.G. Edsell
Author: Indran Davagnanam
Author: Shashivadan P. Hirani
Author: Dan S. Martin
Author: Denny Z.H. Levett
Author: John S. Thornton
Author: Xavier Golay
Author: Lisa Strycharczuk
Author: Stanton P. Newman
Author: Hugh E. Montgomery
Author: Christopher H.E. Imray

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