Maximal Airway Response in Adolescents With Long-term Asthma Remission and Persisting Airway Hypersensitivity: Materials and Methods
However, for airway hypersensitivity to methacholine in symptom-free and medication-free asthmatic adolescents, neither the presence of maximal response plateau nor the severity of excessive airway narrowing has been investigated so far. This is an important issue because several studies have suggested that the mechanisms underlying maximal airway response and airway sensitivity to methacholine are different, and that airway sensitivity is not an adequate measure of maximal airway response.
Corticosteroids are currently the most effective anti-inflammatory drugs available for the treatment of asthma. When inhaled corticosteroids are administered to symptomatic asthmatic subjects, airway sensitivity and the maximal airway response to inhaled methacholine are reduced. Recently, we have shown that inhaled budesonide did not cause a significant improvement in the airway hypersensitivity, as measured by the provocative concentration of methacholine causing a 20% fall in FEV1 (PC20), in adolescents with long-term asthma remission. It is not known, however, whether inhaled corticosteroids could reduce the maximal airway response constituting BHR in this clinical setting.
This study was designed with two main aims. The first aim was to compare the profiles of maximal airway response to high doses of inhaled methacholine between adolescents with long-term asthma remission and currently symptomatic asthmatic adolescents with a similar degree of PC20, and the second aim was to determine whether the maximal response plateau in adolescents with asthma remission and persisting airway hypersensitivity is reduced by prolonged treatment with inhaled corticosteroids.
A group of adolescents with long-term remission of atopic asthma were recruited from the allergy clinic at Seoul National University Children’s Hospital. All subjects had a history of wheezing and dyspnea, and had previous diagnoses of atopic asthma according to the American Thoracic Society criteria.