Inhaled corticosteroids and the beneficial effect of deep inspiration in asthma.
Deep inspiration-induced bronchoprotection and bronchodilation are impaired in asthma. We evaluated the effect of inhaled glucocorticosteroids on these phenomena. Two groups of subjects with asthma, 9 with moderate/severe hyperresponsiveness to methacholine, and 12 with mild/borderline hyperresponsiveness to methacholine, received inhaled fluticasone (880 microg daily) for 12 weeks. Serial bronchoprovocations were performed at Weeks 0, 6, and 12. The impact of deep inspirations on the airway response to methacholine was evaluated on the basis of inspiratory vital capacity and FEV(1). Fluticasone produced a wide spectrum of changes in the beneficial effects of deep inspiration, but the mean changes were not significant. The magnitude of the steroid-induced changes in bronchoprotection by deep inspiration correlated with baseline log PC(20) (the provocative concentration of methacholine causing a 20% fall in FEV(1); higher log PC(20) predicted improvement of the deep inspiration effect). The steroid-induced changes led to the emergence of strong positive correlations between the effects of deep inspiration and the methacholine log PC(20) that did not exist at baseline. We conclude that deep inspiration-induced bronchoprotection can be restored by inhaled glucocorticosteroids only in individuals with mild hyperresponsiveness. After steroid treatment, the beneficial effects of deep inspiration become significant determinants of the magnitude of airway hyperresponsiveness.
Scichilone
Nicola
N
Johns Hopkins Asthma and Allergy Center, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21224, USA.
Permutt
Solbert
S
Bellia
Vincenzo
V
Togias
Alkis
A
D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D000730:Androstadienes / Q000008:administration & dosage* / Q000627:therapeutic use; D001249:Asthma / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology / Q000628:therapy*; D016535:Bronchial Hyperreactivity / Q000209:etiology / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D001993:Bronchodilator Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D005260:Female; D000068298:Fluticasone; D005541:Forced Expiratory Volume; D006801:Humans; D001239:Inhalation; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D015656:Respiratory Mechanics; D012138:Respiratory Therapy; D012720:Severity of Illness Index; D014797:Vital Capacity
D000730:Androstadienes; D016085:Bronchoconstrictor Agents; D001993:Bronchodilator Agents; D016210:Methacholine Chloride; D000068298:Fluticasone