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The physiological effects of hypobaric hypoxia versus normobaric hypoxia: a systematic review of crossover trials

The physiological effects of hypobaric hypoxia versus normobaric hypoxia: a systematic review of crossover trials
The physiological effects of hypobaric hypoxia versus normobaric hypoxia: a systematic review of crossover trials
Much hypoxia research has been carried out at high altitude in a hypobaric hypoxia (HH) environment. Many research teams seek to replicate high-altitude conditions at lower altitudes in either hypobaric hypoxic conditions or normobaric hypoxic (NH) laboratories. Implicit in this approach is the assumption that the only relevant condition that differs between these settings is the partial pressure of oxygen (PO2), which is commonly presumed to be the principal physiological stimulus to adaptation at high altitude. This systematic review is the first to present an overview of the current available literature regarding crossover studies relating to the different effects of HH and NH on human physiology. After applying our inclusion and exclusion criteria, 13 studies were deemed eligible for inclusion. Several studies reported a number of variables (e.g. minute ventilation and NO levels) that were different between the two conditions, lending support to the notion that true physiological difference is indeed present. However, the presence of confounding factors such as time spent in hypoxia, temperature, and humidity, and the limited statistical power due to small sample sizes, limit the conclusions that can be drawn from these findings. Standardisation of the study methods and reporting may aid interpretation of future studies and thereby improve the quality of data in this area. This is important to improve the quality of data that is used for improving the understanding of hypoxia tolerance, both at altitude and in the clinical setting.
normobaric hypoxia, hypobaric hypoxia, altitude
1-20
Coppel, Jonny
6912d59b-c394-4d38-a7d4-c537a3af08dd
Hennis, Philip
7d49a209-ee6d-4d54-845f-8b7781ea5b8e
Gilbert-Kawai, Edward
9babf11e-8fd3-4924-acda-68b62cfa3121
Grocott, Michael P.W.
1e87b741-513e-4a22-be13-0f7bb344e8c2
Coppel, Jonny
6912d59b-c394-4d38-a7d4-c537a3af08dd
Hennis, Philip
7d49a209-ee6d-4d54-845f-8b7781ea5b8e
Gilbert-Kawai, Edward
9babf11e-8fd3-4924-acda-68b62cfa3121
Grocott, Michael P.W.
1e87b741-513e-4a22-be13-0f7bb344e8c2

Coppel, Jonny, Hennis, Philip, Gilbert-Kawai, Edward and Grocott, Michael P.W. (2015) The physiological effects of hypobaric hypoxia versus normobaric hypoxia: a systematic review of crossover trials. Extreme Physiology & Medicine, 4 (2), 1-20. (doi:10.1186/s13728-014-0021-6). (PMID:25722851)

Record type: Article

Abstract

Much hypoxia research has been carried out at high altitude in a hypobaric hypoxia (HH) environment. Many research teams seek to replicate high-altitude conditions at lower altitudes in either hypobaric hypoxic conditions or normobaric hypoxic (NH) laboratories. Implicit in this approach is the assumption that the only relevant condition that differs between these settings is the partial pressure of oxygen (PO2), which is commonly presumed to be the principal physiological stimulus to adaptation at high altitude. This systematic review is the first to present an overview of the current available literature regarding crossover studies relating to the different effects of HH and NH on human physiology. After applying our inclusion and exclusion criteria, 13 studies were deemed eligible for inclusion. Several studies reported a number of variables (e.g. minute ventilation and NO levels) that were different between the two conditions, lending support to the notion that true physiological difference is indeed present. However, the presence of confounding factors such as time spent in hypoxia, temperature, and humidity, and the limited statistical power due to small sample sizes, limit the conclusions that can be drawn from these findings. Standardisation of the study methods and reporting may aid interpretation of future studies and thereby improve the quality of data in this area. This is important to improve the quality of data that is used for improving the understanding of hypoxia tolerance, both at altitude and in the clinical setting.

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More information

Accepted/In Press date: 18 December 2014
Published date: 26 February 2015
Keywords: normobaric hypoxia, hypobaric hypoxia, altitude
Organisations: NIHR Southampton Respiratory Biomedical Research Unit

Identifiers

Local EPrints ID: 384054
URI: http://eprints.soton.ac.uk/id/eprint/384054
PURE UUID: 1c36ab53-8723-49fb-a831-748d6af891e5
ORCID for Michael P.W. Grocott: ORCID iD orcid.org/0000-0002-9484-7581

Catalogue record

Date deposited: 08 Dec 2015 14:42
Last modified: 15 Mar 2024 03:33

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Contributors

Author: Jonny Coppel
Author: Philip Hennis
Author: Edward Gilbert-Kawai

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