Abstract
BackgroundPhysical effort is capable of triggering airway obstruction in asthmatics, the so-called exercise-induced bronchoconstriction in asthma (EIBa). This study was performed in subjects with mild persistent asthma, aiming to find predictors for developing EIBa.MethodsIn 20 subjects with mild asthma, measurements of baseline functional respiratory parameters and airways responsiveness by a methacholine challenge were obtained on the first day. A maximal, symptom-limited incremental cardiopulmonary exercise test (CPExT) was performed the day after, with subsequent, repeated maneuvers of maximal full forced expiration to monitor the FEV1 change at 1,3,5,7,10 and 15 min after the end of the exercise.Results19 subjects completed the two-days protocol. No functional parameters both at rest and during effort were useful to predict EIBa after stopping exercise. In asthmatics with EIBa, mean Inspiratory Capacity (IC) did not increase with increasing ventilatory requirements during CPExT because 6 of them (50%) displayed dynamic pulmonary hyperinflation (DH), as documented by their progressive increase of end-expiratory lung volume. This subgroup, showing earlier post-exercise FEV1 fall, had significantly lower forced mean expiratory flow between 25% and 75% of forced vital capacity (FEF25-75%) at rest (p < 0.05) and higher airways responsiveness, expressed as PD20FEV1 (p < 0.05) as compared with other asthmatics with EIBa.ConclusionsNo functional respiratory parameters seem to predict EIBa in mild asthmatics. However, in those with EIBa, a subgroup developed DH during exercise, and this was associated with a baseline reduced forced expiratory flow rates at lower lung volumes and higher airway hyperresponsiveness, suggesting a prominent small airways impairment.
Highlights
Physical effort is capable of triggering airway obstruction in asthmatics, the so-called exercise-induced bronchoconstriction in asthma (EIBa)
Anthropometric and baseline functional data of the 19 patients of the study are shown in Table 1, all together and divided into 2 groups according to the presence or absence of EIBa
All subjects were treated with inhaled corticosteroids that were withdrawn 4 weeks before the study and 7 (2 in the group without EIBa) with long-acting beta-2 agonists on top
Summary
Physical effort is capable of triggering airway obstruction in asthmatics, the so-called exercise-induced bronchoconstriction in asthma (EIBa). Airflow obstruction occurs soon after the end of exercise mainly due to both osmotic and thermal mechanisms [2, 7, 8], but sometimes may develop during exercise, limiting the subjects’ physical performance [9]. It would be useful to identify simple functional predictors of EIBa, mainly in asthmatic young people, in order to implement reliable strategies to avoid bronchoconstriction and related symptoms after or even during exercise, as much as possible. For this reason, the study aimed to identify functional parameters, either at rest or during exercise, predictors of effort-related airflow obstruction in subjects with persistent mild asthma suspected for EIBa
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