Airway stability and heterogeneity in the constricted lung.
Anafi, Ron C., and Theodore A. Wilson.
Department of Aerospace Engineering and Mechanics, University of Minnesota,
Minneapolis, MN 55455
APStracts 8:0266A, 2001.
The effect of bronchoconstriction on airway resistance is known to be spatially
heterogeneous and dependent on tidal volume. We present a model of a single terminal
airway that explains these features. The model describes a feedback between flow and
airway resistance mediated by parenchymal interdependence and the mechanics of
activated smooth muscle. The pressure-tidal volume relationship for a constricted
terminal airway is computed and shown to be sigmoidal. Constricted terminal airways are
predicted to have two stable states, one effectively open and one nearly closed. We argue
that the heterogeneity of whole lung constriction is a consequence of this behavior.
Airways are partitioned between the two states to accommodate total flow, and changes
in tidal volume and end-expiratory pressure affect the number of airways in each state.
Quantitative predictions for whole lung resistance and elastance agree with data from
previously published studies on lung impedance.
Received 12 February 2001; accepted in final form 7 May 2001
APS Manuscript Number A0144-1.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 18 June 2001