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effect of stratified inequality of blood flow on gas exchange in liquid-filled lungs.This investigation set out to answer two questions: (1) are the distal alveoli in the terminal lung units less well perfused than the proximal alveoli, i.e., is there stratification of blood flow; and (2) if so, does this enhance gas exchange in the presence of stratified inequality of ventilation. Excised dog lungs were ventilated with saline and perfused with blood. Following single inspirations of xenon 133 in saline and various periods of breath holding, the expired xenon concentration against volume was measured and it confirmed marked stratified inequality of ventilation under these conditions. By measuring the rate of depletion of xenon from alveoli during a period of blood flow, we showed that the alveoli which emptied at the end of expiration had 16% less blood flow than those exhaling earlier. However, by measuring the xenon concentration in pulmonary venous blood, we found that about 10% less tracer was transferred from the alveoli into the blood when the inspired xenon was stratified within the respiratory zone. Thus while stratification of blood flow was confirmed, it was shown to impair rather than enhance the efficiency of gas transfer.
Document ID
19720040815
Document Type
Reprint (Version printed in journal)
Authors
West, J. B.
(California, University La Jolla, Calif., United States)
Maloney, J. E.
(Melbourne, University Melbourne, Australia)
Castle, B. L.
(NASA Ames Research Center Biotechnology Div., Moffett Field, Calif., United States)
Date Acquired
August 6, 2013
Publication Date
March 1, 1972
Publication Information
Publication: Journal of Applied Physiology
Volume: 32
Subject Category
BIOSCIENCES
Distribution Limits
Public
Copyright
Other