Abstract
| Originalsprog | Engelsk |
|---|---|
| Tidsskrift | Journal of Physiology |
| Vol/bind | 586 |
| Udgave nummer | 9 |
| Sider (fra-til) | 2381-91 |
| Antal sider | 10 |
| ISSN | 0022-3751 |
| DOI | |
| Status | Udgivet - 2008 |
Bibliografisk note
Keywords: Oxygen; Physical Endurance; Physical Exertion; Pulmonary Alveoli; Pulmonary Artery; Pulmonary Gas ExchangeAdgang til dokumentet
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I: Journal of Physiology, Bind 586, Nr. 9, 2008, s. 2381-91.
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review
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TY - JOUR
T1 - The contribution of intrapulmonary shunts to the alveolar-to-arterial oxygen difference during exercise is very small
AU - Vogiatzis, Ioannis
AU - Zakynthinos, Spyros
AU - Boushel, Robert
AU - Athanasopoulos, Dimitris
AU - Guenette, Jordan A
AU - Wagner, Harrieth
AU - Roussos, Charis
AU - Wagner, Peter D
N1 - Keywords: Oxygen; Physical Endurance; Physical Exertion; Pulmonary Alveoli; Pulmonary Artery; Pulmonary Gas Exchange
PY - 2008
Y1 - 2008
N2 - Exercise is well known to cause arterial PO2 to fall and the alveolar-arterial PO2 difference(Aa PO2 ) to increase. Until recently, the physiological basis for this was considered to be mostly ventilation/perfusion ((.)VA/(.)Q) inequality and alveolar-capillary diffusion limitation. Recently, arterio-venous shunting through dilated pulmonary blood vessels has been proposed to explain a significant part of the Aa PO2 during exercise. To test this hypothesis we determined venous admixture during 5 min of near-maximal, constant-load, exercise in hypoxia (in inspired O2 fraction, FIO2 , 0.13), normoxia (FIO2 , 0.21) and hyperoxia (FIO2 , 1.0) undertaken in balanced order on the same day in seven fit cyclists ((.)VO2max, 61.3 +/- 2.4 ml kg(-1) min(-1); mean +/- S.E.M.).Venous admixture reflects three causes of hypoxaemia combined: true shunt, diffusion limitation and ((.)VA/(.)Q) inequality. In hypoxia, venous admixture was 22.8 +/- 2.5% of the cardiac output; in normoxia it was 3.5 +/- 0.5%; in hyperoxia it was 0.5 +/- 0.2%. Since only true shunt accounts for venous admixture while breathing 100% O2, the present study suggests that shunt accounts for only a very small portion of the observed venous admixture, Aa PO2 and hypoxaemia during heavy exercise.
AB - Exercise is well known to cause arterial PO2 to fall and the alveolar-arterial PO2 difference(Aa PO2 ) to increase. Until recently, the physiological basis for this was considered to be mostly ventilation/perfusion ((.)VA/(.)Q) inequality and alveolar-capillary diffusion limitation. Recently, arterio-venous shunting through dilated pulmonary blood vessels has been proposed to explain a significant part of the Aa PO2 during exercise. To test this hypothesis we determined venous admixture during 5 min of near-maximal, constant-load, exercise in hypoxia (in inspired O2 fraction, FIO2 , 0.13), normoxia (FIO2 , 0.21) and hyperoxia (FIO2 , 1.0) undertaken in balanced order on the same day in seven fit cyclists ((.)VO2max, 61.3 +/- 2.4 ml kg(-1) min(-1); mean +/- S.E.M.).Venous admixture reflects three causes of hypoxaemia combined: true shunt, diffusion limitation and ((.)VA/(.)Q) inequality. In hypoxia, venous admixture was 22.8 +/- 2.5% of the cardiac output; in normoxia it was 3.5 +/- 0.5%; in hyperoxia it was 0.5 +/- 0.2%. Since only true shunt accounts for venous admixture while breathing 100% O2, the present study suggests that shunt accounts for only a very small portion of the observed venous admixture, Aa PO2 and hypoxaemia during heavy exercise.
U2 - 10.1113/jphysiol.2007.150128
DO - 10.1113/jphysiol.2007.150128
M3 - Journal article
C2 - 18339692
SN - 0022-3751
VL - 586
SP - 2381
EP - 2391
JO - Journal of Physiology
JF - Journal of Physiology
IS - 9
ER -