Perception of dyspnea in mild smoking asthmatics

Background: Previous data from the literature reported blunted perception of airway obstruction in severe asthmatics with near fatal asthma. Approximately 25% of patients with asthma are current smokers. Aim: To determine whether there is an alteration in perception of airway obstruction during a non specific provocative challenge with methacholine in mild controlled asthmatics who smoke. Methods: Enrolled in this study were 50 subjects, including 26 mild asthmatics and 24 healthy subjects, all of them current smokers. The first objective was the sensitivity of airway obstruction calculated by the regression slope linking the change in the visual analogic scale (VAS) assessed by the patient and the fall in FEV1 during a methacholine challenge. Results: Asthmatics who smoke had a blunted perception of airway obstruction during the bronchial challenge significantly different from that seen in healthy smokers (p = 0.03). This impaired dyspnea perception was inversely related to baseline VAS (r = -0.29, p<0.05) and positively related to baseline FEV1 (r = 0.35, p<0.05). Perception of airway obstruction was not correlated with age, sex, atopy or with airway inflammation features such as exhaled NO or sputum eosinophils. Conclusion: Mild asthmatics who smoke display reduced dyspnea perception during a nonspecific provocative challenge with methacholine. This altered perception of airway obstruction does not relate to airway inflammation. (C) 2007 Elsevier Ltd. All rights reserved.