Effects of airway tone and volume history on maximal expiratory flow in asthma

J Appl Physiol (1985). 1987 Mar;62(3):1133-40. doi: 10.1152/jappl.1987.62.3.1133.


We assessed the difference between isovolumic maximal expiratory flows (Vmax) using maneuvers begun at mid-lung volumes, so-called partial expiratory flow-volume curves (P), vs. those begun at full inflation, so-called maximal expiratory flow-volume curves (M), in 10 asthmatic subjects before and following obstruction induced by isocapnic hyperpnea with cold air and before and after bronchodilation with a beta-agonist or antimuscarinic agent. Volume history effects were quantitated as an M-to-P ratio of Vmax at 30% vital capacity (M/P V30). Although M/P V30 was variable among patients at base line, there was a uniform increase in M/P V30 during constriction and a consistent decrease below base line after dilation. Blunting of induced obstruction with beta-agonists also diminished the increase in M/P V30. Antimuscarinics, despite equivalent bronchodilation, failed to alter the degree of obstruction induced by cold air or the increase in M/P V30 seen during obstruction. The level of airway tone, as indicated by specific resistance, related directly to the M/P V30. We conclude that the response of the asthmatic lung to a deep inhalation is relatively predictable when acute changes in airway tone are produced.

Publication types

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

MeSH terms

  • Adult
  • Asthma / physiopathology*
  • Atropine
  • Cold Temperature
  • Female
  • Forced Expiratory Flow Rates
  • Humans
  • Isoproterenol
  • Male
  • Peak Expiratory Flow Rate
  • Respiratory System / drug effects
  • Respiratory System / physiopathology*


  • Atropine
  • Isoproterenol