Selected Contribution: Airway caliber in healthy and asthmatic subjects: effects of bronchial challenge and deep inspirations

• Published in: Journal of applied physiology (1985) Vol. 91; no. 1; pp. 506 - 515
• Main Authors: Jensen, Andrew, Atileh, Haytham, Suki, Bela, Ingenito, Edward P., Lutchen, Kenneth R.
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.07.2001
• Subjects: Adult; Airway Resistance; Albuterol; Asthma; Asthma - diagnosis; Asthma - physiopathology; Bronchi - physiopathology; Bronchial Provocation Tests; Bronchoconstriction; Bronchodilator Agents; Computer Systems; Female; Humans; Inspiratory Capacity; Male; Muscular system; Reference Values; Respiratory Physiological Phenomena; Respiratory system
• ISSN: 8750-7587; 1522-1601
• 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.