Airway stability and heterogeneity in the constricted lung

J Appl Physiol (1985). 2001 Sep;91(3):1185-92. doi: 10.1152/jappl.2001.91.3.1185.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Airway Resistance / physiology*
  • Bronchoconstriction / physiology*
  • Elasticity
  • Humans
  • Lung / physiology*
  • Models, Biological*
  • Positive-Pressure Respiration
  • Respiratory Mechanics / physiology
  • Tidal Volume / physiology