University of Tasmania

File(s) not publicly available

Arterial blood gases and oxygen content in climbers on Mount Everest

journal contribution
posted on 2023-05-17, 02:56 authored by Grocott, MP, Martin, DS, Levett, DZ, McMorrow, R, Windsor, J, Montgomery, HE, Ahuja, V, Aref-Adib, G, Burnham, R, Chisholm, A, Clarke, K, Coates, D, Coates, M, Cook, D, Cox, M, Dhillon, S, Dougall, C, Doyle, P, Duncan, P, Edsell, M, Edwards, LM, Evans, L, Gardiner, P, Gunning, P, Hart, N, Harrington, J, Harvey, J, Holloway, C, Howard, D, Hurlbut, D, Imray, C, Ince, C, Jonas, M, van der Kaaij, J, Khosravi, M, Kolfschoten, N, Luery, H, Luks, A, Meale, P, Mitchell, K, Morgan, G, Morgan, J, Murray, A, Mythen, M, Newman, S, O'Dwyer, M, Pate, J, Plant, T, Pun, M, Richards, P, Richardson, A, Rodway, G, Simpson, J, Stroud, C, Stroud, M, Stygal, J, Symons, B, Szawarski, P, Van Tulleken, A, Van Tulleken, C, Vercueil, A, Wandrag, L, Wilson, M, Basnyat, B, Clarke, C, Hornbein, T, Milledge, J, West, J
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 (PaO2) and carbon dioxide (PaCO2), pH, and hemoglobin and lactate concentrations were measured. The arterial oxygen saturation (SaO2), bicarbonate concentration, base excess, and alveolar-arterial oxygen difference were calculated. Results: PaO2 fell with increasing altitude, whereas SaO2 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 PaO2 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 PaCO2 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. Copyright © 2009 Massachusetts Medical Society.


Publication title

New England Journal of Medicine








Tasmanian School of Medicine


Massachusetts Medical Soc/Nejm

Place of publication

Waltham Woods Center, 860 Winter St,, Waltham, USA, Ma, 02451-1413

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the health sciences

Usage metrics

    University Of Tasmania


    Ref. manager