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Arterial blood gases and oxygen content in climbers on Mount Everest

Arterial blood gases and oxygen content in climbers on Mount Everest
Arterial blood gases and oxygen content in climbers on Mount Everest
BACKGROUND: The level of environmental hypobaric hypoxia that affects climbers at the summit of Mount Everest (8848 m [29,029 ft]) is close to the limit of tolerance by humans. We performed direct field measurements of arterial blood gases in climbers breathing ambient air on Mount Everest.

METHODS: We obtained samples of arterial blood from 10 climbers during their ascent to and descent from the summit of Mount Everest. The partial pressures of arterial oxygen (PaO(2)) and carbon dioxide (PaCO(2)), pH, and hemoglobin and lactate concentrations were measured. The arterial oxygen saturation (SaO(2)), bicarbonate concentration, base excess, and alveolar-arterial oxygen difference were calculated.

RESULTS: PaO(2) fell with increasing altitude, whereas SaO(2) was relatively stable. The hemoglobin concentration increased such that the oxygen content of arterial blood was maintained at or above sea-level values until the climbers reached an elevation of 7100 m (23,294 ft). In four samples taken at 8400 m (27,559 ft)--at which altitude the barometric pressure was 272 mm Hg (36.3 kPa)--the mean PaO(2) in subjects breathing ambient air was 24.6 mm Hg (3.28 kPa), with a range of 19.1 to 29.5 mm Hg (2.55 to 3.93 kPa). The mean PaCO(2) was 13.3 mm Hg (1.77 kPa), with a range of 10.3 to 15.7 mm Hg (1.37 to 2.09 kPa). At 8400 m, the mean arterial oxygen content was 26% lower than it was at 7100 m (145.8 ml per liter as compared with 197.1 ml per liter). The mean calculated alveolar-arterial oxygen difference was 5.4 mm Hg (0.72 kPa).

CONCLUSIONS: The elevated alveolar-arterial oxygen difference that is seen in subjects who are in conditions of extreme hypoxia may represent a degree of subclinical high-altitude pulmonary edema or a functional limitation in pulmonary diffusion.
140-149
Grocott, Michael P.W.
1e87b741-513e-4a22-be13-0f7bb344e8c2
Martin, Daniel S.
3e441b48-9221-4308-8ae6-49cbde20753f
Levett, Denny Z.H.
4b33b751-32be-4fa3-aaf7-b62e62f08de8
McMorrow, Roger
d6228e27-c305-4171-9cb1-68590cabb847
Windsor, Jeremy
a90638f6-fdf2-49ff-b73b-f50b2d63cf3d
Montgomery, Hugh E.
8082956e-3142-42b4-9f46-b0c9cee79785
Caudwell Xtreme Everest Research Group
Grocott, Michael P.W.
1e87b741-513e-4a22-be13-0f7bb344e8c2
Martin, Daniel S.
3e441b48-9221-4308-8ae6-49cbde20753f
Levett, Denny Z.H.
4b33b751-32be-4fa3-aaf7-b62e62f08de8
McMorrow, Roger
d6228e27-c305-4171-9cb1-68590cabb847
Windsor, Jeremy
a90638f6-fdf2-49ff-b73b-f50b2d63cf3d
Montgomery, Hugh E.
8082956e-3142-42b4-9f46-b0c9cee79785

Grocott, Michael P.W., Martin, Daniel S., Levett, Denny Z.H., McMorrow, Roger, Windsor, Jeremy and Montgomery, Hugh E. , Caudwell Xtreme Everest Research Group (2009) Arterial blood gases and oxygen content in climbers on Mount Everest. New England Journal of Medicine, 360 (2), 140-149. (doi:10.1056/NEJMoa0801581). (PMID:19129527)

Record type: Article

Abstract

BACKGROUND: The level of environmental hypobaric hypoxia that affects climbers at the summit of Mount Everest (8848 m [29,029 ft]) is close to the limit of tolerance by humans. We performed direct field measurements of arterial blood gases in climbers breathing ambient air on Mount Everest.

METHODS: We obtained samples of arterial blood from 10 climbers during their ascent to and descent from the summit of Mount Everest. The partial pressures of arterial oxygen (PaO(2)) and carbon dioxide (PaCO(2)), pH, and hemoglobin and lactate concentrations were measured. The arterial oxygen saturation (SaO(2)), bicarbonate concentration, base excess, and alveolar-arterial oxygen difference were calculated.

RESULTS: PaO(2) fell with increasing altitude, whereas SaO(2) was relatively stable. The hemoglobin concentration increased such that the oxygen content of arterial blood was maintained at or above sea-level values until the climbers reached an elevation of 7100 m (23,294 ft). In four samples taken at 8400 m (27,559 ft)--at which altitude the barometric pressure was 272 mm Hg (36.3 kPa)--the mean PaO(2) in subjects breathing ambient air was 24.6 mm Hg (3.28 kPa), with a range of 19.1 to 29.5 mm Hg (2.55 to 3.93 kPa). The mean PaCO(2) was 13.3 mm Hg (1.77 kPa), with a range of 10.3 to 15.7 mm Hg (1.37 to 2.09 kPa). At 8400 m, the mean arterial oxygen content was 26% lower than it was at 7100 m (145.8 ml per liter as compared with 197.1 ml per liter). The mean calculated alveolar-arterial oxygen difference was 5.4 mm Hg (0.72 kPa).

CONCLUSIONS: The elevated alveolar-arterial oxygen difference that is seen in subjects who are in conditions of extreme hypoxia may represent a degree of subclinical high-altitude pulmonary edema or a functional limitation in pulmonary diffusion.

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More information

Published date: 8 January 2009
Organisations: Dev Origins of Health & Disease

Identifiers

Local EPrints ID: 183311
URI: http://eprints.soton.ac.uk/id/eprint/183311
PURE UUID: fe7d71fe-8799-44cd-85b7-7b1dbaecd917
ORCID for Michael P.W. Grocott: ORCID iD orcid.org/0000-0002-9484-7581

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Date deposited: 03 May 2011 09:06
Last modified: 15 Mar 2024 03:33

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Contributors

Author: Daniel S. Martin
Author: Denny Z.H. Levett
Author: Roger McMorrow
Author: Jeremy Windsor
Author: Hugh E. Montgomery
Corporate Author: Caudwell Xtreme Everest Research Group

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