Document Detail

VA/Q inhomogeneity and AaDO2 in man during exercise: effect of SF6 breathing.
MedLine Citation:
PMID:  711565     Owner:  NLM     Status:  MEDLINE    
Pulmonary gas exchange was studied in five normal subjects both at rest and during moderate steady-state exercise on a bicycle ergometer while breathing a) room air and b) a mixture of 20.9% O2-balance sulfur hexafluoride (SF6). The alveolar-arterial oxygen pressure differences (AaDO2) widened significantly from rest to exercise. Breathing the O2-SF6 mixture reduced the AaDo2 significantly from 10.9 to 4.2 Torr at rest and from 15.5 to 10.1 Torr during exercise (P less than or equal to 0.01). There were no concurrent changes in metabolism, cardiac output, or heart rate during the SF6 breathing. Possible changes in the anatomic shunt fraction, alveolar-end-capillary equilibration, or the distribution of blood flow cannot account for these observations. We conclude that the AaDO2 increase during exercise reflects an inhomogeneity of ventilation-perfusion ratios (VA/Q) most probably arising within regions of the lung (intraregional inhomogeneity) rather than between regions (interregional inhomogeneity).
N Gledhill; A B Froese; F J Buick; A C Bryan
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of applied physiology: respiratory, environmental and exercise physiology     Volume:  45     ISSN:  0161-7567     ISO Abbreviation:  J Appl Physiol Respir Environ Exerc Physiol     Publication Date:  1978 Oct 
Date Detail:
Created Date:  1979-01-24     Completed Date:  1979-01-24     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  7801242     Medline TA:  J Appl Physiol Respir Environ Exerc Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  512-5     Citation Subset:  IM; S    
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MeSH Terms
Carbon Dioxide / blood
Heart Rate
Lung / physiology
Lung Volume Measurements
Oxygen / blood
Physical Exertion*
Ventilation-Perfusion Ratio
Reg. No./Substance:
0/Fluorides; 124-38-9/Carbon Dioxide; 7704-34-9/Sulfur; 7782-44-7/Oxygen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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