Rationale: Bronchoconstriction after deep inhalation is associated with increased severity of asthma and is also a predictor of length of hospital stay in individuals admitted with asthma exacerbations. We hypothesized that this effect may represent a new non-invasive method to assess bronchial reactivity and other measures of asthma control.
Methods: We used a cross-sectional study design recruiting participants 18 to 65 years of age with a physician diagnosis of asthma. All participants were asked to provide three serial peak expiratory flow rate (PEFR) measurements in the morning, and bronchial reactivity was measured up to a maximum inhaled dose of 24.5 micromoL methacholine on the same day. Participants also recorded their asthma symptoms score and bronchodilator use during the 7 days before measuring bronchial reactivity.
Results: A total of 127 people provided data for analysis. There was no significant relationship between bronchoconstriction after deep inhalation (as measured by three serial PEFR measurements) and either bronchial reactivity to methacholine, asthma symptoms, or bronchodilator use.
Conclusions: Bronchoconstriction induced by deep inspiration does not appear to be a valid marker of airway hyperresponsiveness or asthma severity in adults with mild to moderate asthma.