학술논문
Systemic oxygen extraction during exercise at high altitude
Document Type
Academic Journal
Author
Martin, D. S.; Cobb, A.; Meale, P.; Mitchell, K.; Edsell, M.; Mythen, M. G.; Grocott, M. P. W.; Adams, Tom; Biseker, Lindsay; Booth, Adam; Burdall, Oliver; Cobb, Alexandra; Cumpstey, Andrew; Dauncey, Steve; Edsell, Mark; Farrant, James; Feelisch, Martin; Fernandez, Bernadette; Firth, Oliver; Gilbert, Edward; Grant, Daniel; Grocott, Michael; Hennis, Phil; Jackson, Laura; Jenner, Will; van der Kaaij, Jildou; Khosravi, Maryam; Kortekaas, Edith; Levett, Denny; Mahomed, Zeyn; Martin, Daniel; Meale, Paula; Milledge, Jim; Mitchell, Kay; Mole, Damian; Moses, Oliver; Mythen, Michael; Rigat, Fabio; OʼDoherty, Alasdair; Salam, Alex; Sanborn, Matt; Sheperdigian, Adam; Shrubb, Fiona; Simpson, Jo; Talbot, Nick; Wandrag, Liesel; Wijesingha, Savini; Williamson, Wilby; Woolley, Tom; Yow, Heng
Source
British Journal of Anaesthesia. Apr 01, 2015 114(4):677-682
Subject
Language
English
ISSN
0007-0912
Abstract
BACKGROUND: Classic teaching suggests that diminished availability of oxygen leads to increased tissue oxygen extraction yet evidence to support this notion in the context of hypoxaemia, as opposed to anaemia or cardiac failure, is limited. METHODS: At 75 m above sea level, and after 7–8 days of acclimatization to 4559 m, systemic oxygen extraction [C(a−v)O2] was calculated in five participants at rest and at peak exercise. Absolute [C(a−v)O2] was calculated by subtracting central venous oxygen content (CcvO2) from arterial oxygen content (Equation is included in full-text article.)in blood sampled from central venous and peripheral arterial catheters, respectively. Oxygen uptake (Equation is included in full-text article.)was determined from expired gas analysis during exercise. RESULTS: Ascent to altitude resulted in significant hypoxaemia; median (range) (Equation is included in full-text article.)87.1 (82.5–90.7)% and (Equation is included in full-text article.)6.6 (5.7–6.8) kPa. While absolute C(a−v)O2 was reduced at maximum exercise at 4559 m [83.9 (67.5–120.9) ml litre vs 99.6 (88.0–151.3) ml litre at 75 m, P=0.043], there was no change in oxygen extraction ratio (OER) [C(a−v)O2/CaO2] between the two altitudes [0.52 (0.48–0.71) at 4559 m and 0.53 (0.49–0.73) at 75 m, P=0.500]. Comparison of C(a−v)O2 at peak (Equation is included in full-text article.)at 4559 m and the equivalent (Equation is included in full-text article.)at sea level for each participant also revealed no significant difference [83.9 (67.5–120.9) ml litre vs 81.2 (73.0–120.7) ml litre, respectively, P=0.225]. CONCLUSION: In acclimatized individuals at 4559 m, there was a decline in maximum absolute C(a−v)O2 during exercise but no alteration in OER calculated using central venous oxygen measurements. This suggests that oxygen extraction may have become limited after exposure to 7–8 days of hypoxaemia.