TY - JOUR
T1 - Cerebral artery dilatation maintains cerebral oxygenation at extreme altitude and in acute hypoxia--an ultrasound and MRI study
AU - Wilson, Mark H.
AU - Edsell, Mark E. G.
AU - Davagnanam, Indran
AU - Hirani, Shashivadan P.
AU - Martin, Dan S.
AU - Levett, Denny Z. H.
AU - Thornton, John S.
AU - Golay, Xavier
AU - Strycharczuk, Lisa
AU - Newman, Stanton P.
AU - Montgomery, Hugh E.
AU - Grocott, Mike P. W.
AU - Imray, Christopher H. E.
AU - AUTHOR GROUP
AU - Ahuja, V.
AU - Aref-Adib, G.
AU - Burnham, R.
AU - Chisholm, A.
AU - Clarke, K.
AU - Coates, D.
AU - Coates, M.
AU - Cook, D.
AU - Cox, M.
AU - Dhillon, S.
AU - Dougall, C.
AU - Doyle, P.
AU - Duncan, P.
AU - Edsell, M.
AU - Edwards, L.
AU - Evans, L.
AU - Gardiner, P.
AU - Grocott, M.
AU - Gunning, P.
AU - Hart, N.
AU - Harrington, J.
AU - Harvey, J.
AU - Holloway, C.
AU - Howard, D.
AU - Hurlbut, D.
AU - Imray, C.
AU - Ince, C.
AU - Jonas, M.
AU - van der Kaaij, J.
AU - Khosravi, M.
AU - Kolfschoten, N.
AU - Levett, D.
AU - Luery, H.
AU - Luks, A.
AU - Martin, D.
AU - McMorrow, R.
AU - Meale, P.
PY - 2011
Y1 - 2011
N2 - 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
AB - 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
U2 - https://doi.org/10.1038/jcbfm.2011.81
DO - https://doi.org/10.1038/jcbfm.2011.81
M3 - Article
C2 - 21654697
SN - 0271-678X
VL - 31
SP - 2019
EP - 2029
JO - Journal of cerebral blood flow and metabolism
JF - Journal of cerebral blood flow and metabolism
IS - 10
ER -