Specific effect of hypobaria on cerebrovascular hypercapnic responses in hypoxia.

Details

Ressource 1Request a copy Sous embargo indéterminé.
State: Public
Version: author
License: CC BY 4.0
Serval ID
serval:BIB_8A7E5FAA115D
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Specific effect of hypobaria on cerebrovascular hypercapnic responses in hypoxia.
Journal
Physiological reports
Author(s)
Aebi M.R., Bourdillon N., Kunz A., Bron D., Millet G.P.
ISSN
2051-817X (Electronic)
ISSN-L
2051-817X
Publication state
Published
Issued date
02/2020
Peer-reviewed
Oui
Volume
8
Number
4
Pages
e14372
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
It remains unknown whether hypobaria plays a role on cerebrovascular reactivity to CO <sub>2</sub> (CVR). The present study evaluated the putative effect of hypobaria on CVR and its influence on cerebral oxygen delivery (cDO <sub>2</sub> ) in five randomized conditions (i.e., normobaric normoxia, NN, altitude level of 440 m; hypobaric hypoxia, HH at altitude levels of 3,000 m and 5,500 m; normobaric hypoxia, NH, altitude simulation of 5,500 m; and hypobaric normoxia, HN). CVR was assessed in nine healthy participants (either students in aviation or pilots) during a hypercapnic test (i.e., 5% CO <sub>2</sub> ). We obtained CVR by plotting middle cerebral artery velocity versus end-tidal CO <sub>2</sub> pressure (P <sub>ET</sub> CO <sub>2</sub> ) using a sigmoid model. Hypobaria induced an increased slope in HH (0.66 ± 0.33) compared to NH (0.35 ± 0.19) with a trend in HN (0.46 ± 0.12) compared to NN (0.23 ± 0.12, p = .069). P <sub>ET</sub> CO <sub>2</sub> was decreased (22.3 ± 2.4 vs. 34.5 ± 2.8 mmHg and 19.9 ± 1.3 vs. 30.8 ± 2.2 mmHg, for HN vs. NN and HH vs. NH, respectively, p < .05) in hypobaric conditions when compared to normobaric conditions with comparable inspired oxygen pressure (141 ± 1 vs. 133 ± 3 mmHg and 74 ± 1 vs. 70 ± 2 mmHg, for NN vs. HN and NH vs. HH, respectively) During hypercapnia, cDO <sub>2</sub> was decreased in 5,500 m HH (p = .046), but maintained in NH when compared to NN. To conclude, CVR seems more sensitive (i.e., slope increase) in hypobaric than in normobaric conditions. Moreover, hypobaria potentially affected vasodilation reserve (i.e., MCAv autoregulation) and brain oxygen delivery during hypercapnia. These results are relevant for populations (i.e., aviation pilots; high-altitude residents as miners; mountaineers) occasionally exposed to hypobaric normoxia.
Keywords
cerebral blood flow autoregulation, cerebral oxygen delivery, hypobaria, hypoxia
Pubmed
Open Access
Yes
Create date
27/02/2020 14:36
Last modification date
22/02/2021 10:42
Usage data