Central airways behave more stiffly during forced expiration in patients with asthma

Chronic inflammation and extracellular remodeling of the airway wall charac terize asthma. The purpose of this study was to examine whether these featu res cause a change in airway mechanical properties. We examined 14 healthy and 10 young adults with long-lasting asthma, the latter treated with inhal ed bronchodilators and corticosteroids. To obtain area-versus-transmural pr essure (A-Ptm) curves during forced expiration (Pedersen, O. F., et al. J. Appl. Physiol. 1982;52:357-369), we used an esophageal balloon and a Pitot static probe positioned at five locations between the right lower lobe and midtrachea. Cross-sectional area (A), airway compliance (Caw = dA/dPtm), an d specific airway compliance (sCaw = Caw/A) were obtained from the A-Ptm cu rves. Results showed that: (1) A was larger in males than in females; (2) C aw and sCaw decreased with a more downstream position; and (3) Caw and sCaw were significantly lower in the patients with asthma, with the differences between the asthmatic patients and the healthy subjects becoming smaller t oward the trachea. The lower Caw and sCaw in the patients with long-lasting asthma support the concept that chronic inflammation and remodeling of the airway wall may result in stiffer dynamic elastic properties of the asthma tic airway.