Perception of bronchoconstriction in obstructive pulmonary diseases (disease-specific dyspnoea)

The perception of dyspnoea differs between subjects with obstructive pulmonary diseases, partly because the underlying mechanisms for bronchoconstriction are different. We investigated the perception of bronchoconstriction in subjects with bronchiectasis, asthma and chronic bronchitis and possible contributing factors. Forty-seven non-smoking subjects with bronchiectasis, 50 subjects with asthma and 31 with chronic bronchitis were challenged with histamine. The Borg score was assessed before and after each challenge. The perception score corresponding to a fall in the forced expiratory volume in 1 s (FEV¹) by 20% (PS²⁰) was calculated. The mean values of ΔBorg/ΔFEV¹ (the Borg score change divided by the change in FEV¹ as a percentage of the baseline FEV¹) and PS²⁰ of subjects with bronchiectasis and chronic bronchitis were significantly lower than in subjects with asthma after histamine challenge. The ratio of non-perceivers was higher in bronchiectasis (25.5%) and in chronic bronchitis (32.3%) than in asthma (4.0%). When all subjects were considered, ΔBorg/ΔFEV¹ values were significantly related to female sex (r²=11.5%, P=0.0001), but not to age, duration of the disease, PD²⁰ or baseline FEV¹%. The present study indicates that perception of histamine-induced bronchoconstriction is lower in patients with bronchiectasis and chronic bronchitis than in asthmatic patients, and that sex partially contributes to this difference.