[Asthma patients' perception of dyspnea during acute bronchoconstriction]

The aim of this study was to analyze variations in the perception of acute bronchial obstruction among asthmatics in our practice and to try to define the variables that influence inter-individual differences. We studied 153 asthmatics in stable condition, using a Borg scale to measure dyspnea perceived during a histamine bronchial challenge test. To study individual perception we analyzed both absolute magnitude of perception of dyspnea on the Borg scale when forced expiratory volume in 1 second (FEV1) fell 20% (perception score 20-PS20) and the mathematical difference between PS20 and baseline dyspnea (change in Borg, CB). The results were as follows. 1) The factors that affected PS20 according to multiple linear regression were anxiety, baseline dyspnea and the provocative concentration required to produce a 20% fall in FEV1 (PC20). 2) Within each level of asthma severity, there were differences in dyspnea perception when FEV1 fell 20% (analysis of variance of repeated measures), such that patients with mild asthma and no bronchial obstruction perceived more change in dyspnea. 3) CB during the bronchial challenge test distinguished four ways of perceiving dyspnea: 15% were dysperceivers, 13% were hypoperceivers, 48% were normoperceivers and 24% were hyperperceivers. 4) Hypoperceivers and dysperceivers were at greater risk of severe exacerbation whereas hyperperceivers requested unnecessary medical consultations. 5) Subjects with poorer quality of life were usually dysperceivers; hyperperceivers were the second most common type among those with poorer quality of life. In conclusion, a large percentage of asthmatics do not appropriately perceive acute bronchial obstruction, and the simplest way to evaluate their perception is to calculate the change in dyspnea (on a Borg scale) during the bronchial challenge test. The manner of perceiving dyspnea can not be predicted beforehand, yet it has a significant impact on the use of medical resources and patient quality of life, among other aspects.