Perception of bronchoconstriction in asthma patients measured during histamine challenge test

This study investigated two aspects of the perception of bronchoconstrictio n ("sensitivity" and "absolute perceptual magnitude") in asthmatic patients and identified which clinical characteristics are related to these two asp ects of perception of bronchoconstriction. The perception of histamine induced bronchoconstriction was measured in 128 asthmatic patients. Subjects quantified their breathlessness on a Visual A nalogue Scale (VAS) before forced expiratory volume in one second (FEV1 was measured after each inhalation of histamine. The perceptive "sensitivity" for changes in FEV1 was analysed by the "VAS percentage fall in FEV1" slope . The "absolute perceptual magnitude" was determined by the VAS value at a 20% fall in FEV1, Spearman correlations were used for analysis between the two aspects of perception and asthma symptoms, peak flow variability, bronc hial responsiveness and FEV1 % predicted. Patients with a low "sensitivity" for changes in FEV1 were more likely to s how a frequent peak flow variability (Rs=-0.21; p<0.05), a high bronchial r esponsiveness (Rs=0.37; p<0.001) and a low baseline FEV1 % pred (Rs=0.22; p <0.05), Patient's "absolute perceptual magnitude" correlated positively wit h symptoms during daily life (significant correlations varied 0.21-0.32) bu t not with the lung function parameters. The severity of asthma reflected by a low lung function and a high bronchia l responsiveness, is associated with a low "sensitivity" for changes in for ced expiratory volume in one second. A patient's "absolute perceptual magni tude" is positively related with asthma symptoms during daily life.