Selected contribution: airway caliber in healthy and asthmatic subjects: effects of bronchial challenge and deep inspirations

J Appl Physiol (1985). 2001 Jul;91(1):506-15; discussion 504-5. doi: 10.1152/jappl.2001.91.1.506.


In 9 healthy and 14 asthmatic subjects before and after a standard bronchial challenge and a modified [deep inspiration (DI), inhibited] bronchial challenge and after albuterol, we tracked airway caliber by synthesizing a method to measure airway resistance (Raw; i.e., lung resistance at 8 Hz) in real time. We determined the minimum Raw achievable during a DI to total lung capacity and the subsequent dynamics of Raw after exhalation and resumption of tidal breathing. Results showed that even after a bronchial challenge healthy subjects can dilate airways maximally, and the dilation caused by a single DI takes several breaths to return to baseline. In contrast, at baseline, asthmatic subjects cannot maximally dilate their airways, and this worsens considerably postconstriction. Moreover, after a DI, the dilation that does occur in airway caliber in asthmatic subjects constricts back to baseline much faster (often after a single breath). After albuterol, asthmatic subjects could dilate airways much closer to levels of those of healthy subjects. These data suggest that the asthmatic smooth muscle resides in a stiffer biological state compared with the stimulated healthy smooth muscle, and inhibiting a DI in healthy subjects cannot mimic this.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Airway Resistance
  • Albuterol
  • Asthma / diagnosis
  • Asthma / physiopathology*
  • Bronchi / physiopathology*
  • Bronchial Provocation Tests
  • Bronchoconstriction
  • Bronchodilator Agents
  • Computer Systems
  • Female
  • Humans
  • Inspiratory Capacity
  • Male
  • Reference Values
  • Respiratory Physiological Phenomena


  • Bronchodilator Agents
  • Albuterol