The role of microvascular fluid shifts in the adaptation to hypobaric hypoxia and its contribution to the pathophysiology of AMS (acute mountain sickness) is unresolved. In a systematic prospective study, we investigated the effects of hypobaric hypoxia and physical exercise alone, and in combination, on microvascular fluid exchange and related factors. We used computer-assisted VCP (venous congestion plethysmography) on the calves of ten altitude-acclimatized volunteers. We investigated the effects of: (i) actively climbing to an altitude of 3196 m, (ii) airlifting these subjects to the same altitude, and (iii) exercise at low altitude. CFC (capillary filtration capacity), Pvi (isovolumetric venous pressure) and Qa (calf blood flow) were assessed before and after each procedure and then repeated after an overnight rest. Measurements of CFC showed no evidence of increased microvascular permeability after any of the procedures. Pvi was significantly decreased (P<0.001) from 20.3±4.4 to 8.9±4.3 mmHg after active ascent, and was still significantly lower (P=0.009) after overnight rest at high altitude (13.6±5.9 mmHg). No such changes were observed after the passive ascent (16.7±4.0 mmHg at baseline; 17.3±4.5 mmHg after passive ascent; and 19.9±5.3 mmHg after overnight rest) or after exercise at low altitude. After the active ascent, Qa was significantly increased. We also found a significant correlation between Qa, Pvi and the number of circulating white blood cells. In conclusion, we found evidence to support the hypothesis that increased microvascular permeability associated with AMS does not occur in acclimatized subjects. We also observed that the microvascular equilibrium pressure (Pvi) fell in inverse relation to the increase in Qa, especially in hypoxic exercise. We hypothesize that this inverse relationship reflects the haemodynamic changes at the microvascular interface, possibly attributable to the flow-induced increases in endothelial surface shear forces.
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February 2006
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Research Article|
January 17 2006
Effect of high altitude and exercise on microvascular parameters in acclimatized subjects
Andreas Bauer;
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
Correspondence: Dr Andreas Bauer (email [email protected]).
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Florian Demetz;
Florian Demetz
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
†South Tyrolean Mountain Rescue, Brauereistrasse 18, 39010 Vilpian, Italy
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Dirk Bruegger;
Dirk Bruegger
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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Martin Schmoelz;
Martin Schmoelz
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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Sebastian Schroepfer;
Sebastian Schroepfer
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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André Martignoni;
André Martignoni
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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Heiko Baschnegger;
Heiko Baschnegger
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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Josef Hoelzl;
Josef Hoelzl
†South Tyrolean Mountain Rescue, Brauereistrasse 18, 39010 Vilpian, Italy
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Manfred Thiel;
Manfred Thiel
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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Alexander Choukér;
Alexander Choukér
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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Klaus Peter;
Klaus Peter
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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John Gamble;
John Gamble
‡School of Sport and Exercise Sciences, University of Birmingham, Birmingham B15 2TT, U.K.
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Frank Christ
Frank Christ
*Clinic for Anaesthesiology, Ludwig-Maximilians University Munich, Marchioninistr. 15, 81377 Munich, Germany
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Publisher: Portland Press Ltd
Received:
July 15 2005
Revision Received:
September 07 2005
Accepted:
September 29 2005
Accepted Manuscript online:
September 29 2005
Online ISSN: 1470-8736
Print ISSN: 0143-5221
The Biochemical Society
2006
Clin Sci (Lond) (2006) 110 (2): 207–215.
Article history
Received:
July 15 2005
Revision Received:
September 07 2005
Accepted:
September 29 2005
Accepted Manuscript online:
September 29 2005
Citation
Andreas Bauer, Florian Demetz, Dirk Bruegger, Martin Schmoelz, Sebastian Schroepfer, André Martignoni, Heiko Baschnegger, Josef Hoelzl, Manfred Thiel, Alexander Choukér, Klaus Peter, John Gamble, Frank Christ; Effect of high altitude and exercise on microvascular parameters in acclimatized subjects. Clin Sci (Lond) 1 February 2006; 110 (2): 207–215. doi: https://doi.org/10.1042/CS20050217
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