The perception of dyspnea after bronchoconstriction and bronchodilation in patients with asthma

AbstractBackground: It is well documented that the perception of dyspnea (POD), subjectively reported by patients, is an important index used to guide treatment. The severity of dyspnea following methacholine-induced bronchoconstriction and added mechanical loads is increasing in popular. No formal attention has been addressed to the reduction in dyspnea following bronchodilators. Study objective: To investigate if the magnitude of dyspnea perceived by a subject is independent on the direction (e.g., bronchoconstriction or bronchodilation) of the change in airway resistance. Methods: The POD was measured in 26 mild–moderate asthmatic patients following bronchodilation, using β2-agonists, and following bronchoconstriction, induced by methacholine challenge, to almost the same magnitude. Results: The increase in forced expiratory volume in 1s (FEV1), 30min after the inhalation of β2-agonist (mean±SEM 22.3±0.8%), was associated with a statistically significant decrease (P<0.005) in the POD. The mean decrease in FEV1 following methacoline challenge, was 23±0.7% and was followed by a statistically significant increase (P