Physiological assessment of inflammation in the peripheral lung of asthmatic patients.

Even the asymptomatic asthmatic person with normal lung function may have peripheral airway obstruction and inflammation along with hyperresponsiveness to nonspecific challenges. The airway caliber change induced immediately following a deep inhalation (DI) appears to relate to the mechanism (inflammation vs. smooth muscle constriction) and site (peripheral vs. more central) of obstruction and the degree of hyperresponsiveness. Data are presented and reviewed that support the notion that relative hysteresis of parenchyma (including peripheral airways and alveolar ducts) and airways (more centrally located, conducting airways) can explain the magnitude and sign of airway caliber change that follow a DI in asthmatic subjects.