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Phase V of the single-breath washout testA downward-deflecting phase V is often seen following the terminal rise (phase IV) in single-breath washout tests. To investigate the nature of phase V, experiments using simultaneous washouts of N2 and tracer boluses of Ar were performed on eight normal nonsmoking subjects aged 27-41 who exhibited a phase V. Phase V is found to occur in all subjects at expiratory flow rates between 0.1 and 2.0 l/sec shortly after expiration became flow limited. Volumes of both phases IV and V increase with increasing flow rate. The difference between the exhaled volumes at which flow became limited and phase V appeared is shown to be approximately equal to the anatomic dead space. Results support a model of lung emptying in a gravitational field in which flow limitation occurs first in the lower lung regions and then progresses toward the upper regions, causing phase IV. A decrease in the amount of flow from the upper relative to the lower regions after all regions have become flow limited then causes phase V.
Document ID
19820038393
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Nichol, G. M.
(California Univ. La Jolla, CA, United States)
Michels, D. B.
(California Univ. La Jolla, CA, United States)
Guy, H. J. B.
(Christchurch Clinical School of Medicine, Christchurch, New Zealand; California, University La Jolla, CA, United States)
Date Acquired
August 10, 2013
Publication Date
January 1, 1982
Publication Information
Publication: Journal of Applied Physiology: Respiratory
Subject Category
Aerospace Medicine
Accession Number
82A21928
Funding Number(s)
CONTRACT_GRANT: NSG-9075
Distribution Limits
Public
Copyright
Other

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