Perception of acute airway function changes by patients with mild asthma

The objective of this study was to compare the perception of dyspnea during acute bronchoconstriction and bronchodilation in patients with mild asthma with normal lung function who never experienced severe asthma exacerbations in the past. We studied 83 mild, stable asthmatic patients aged 18-58 years. All patients underwent the methacholine challenge followed by the bronchodilation test with salbutamol. The perceptual sensitivity of changes in airway function was analyzed by linear regression coefficients, slope alpha(constr), and slope alpha(dilat). Additionally, the perception score was determined at a 20% decrease in FEV(1) (PS(20)) during the methacholine challenge. The finding was that perceptual sensitivity for bronchoconstriction and bronchodilation, expressed as slope alpha(constr) and slope alpha(dilat), was similar in the study subjects (mean +/- SD, 0.09 +/- 0.05 and 0.10 +/- 0.05, respectively). The two subgroups under assessment were named poor perceivers when PS(20) < 1 (n = 19) and good perceivers when PS(20) > or = 1 (n = 64). While assessing them, the values of slope alpha(constr) did not differ from the values of slope alpha(dilat) in either of the subgroups of poor perceivers or good perceivers. However, the poor perceivers sensed changes in airway function significantly less than the good perceivers did, although overlapping values of slope alpha were observed. In conclusion, this study indicates that perceptual sensitivity during acute bronchoconstriction and bronchodilation is comparably the same in mild, stable asthmatic patients. However, some of these asthmatic patients may display a diminished perception of dyspnea, which can lead to the deterioration of their asthma without their noticing the corresponding symptoms. Thus, they may delay treatment for acute asthma.