Prevalence of Hyperventilation Syndrome in Difficult Asthma

There is only one visit. During this visit, each patient will complete self-questionnaires like Nijmegen, Hospital Anxiety and Depression Scale(HAD), Short-Form 36(SF36), and Asthma Quality of Life Questionnaire (AQLQ), The participants will have baseline spirometry and fractional exhaled nitric oxide measured at expiratory flow of 50 mL/s (FENO50), blood gases at rest, an hyperventilation challenge and Cardiopulmonary Exercise Testing(CPET) to determine accurately the presence or not of chronic hyperventilation syndrome. The diagnosis is confirmed by two positive tests (Nijmegen, Hyperventilation challenge and blood gases) and the final decision of a medical committee. The first step is to determine the prevalence oh this syndrome in this specific population. The second step is to assess the sensitivity, the specificity, the false positive rate and the false negative rate of the different parameters measured during the tests.

Inclusion criteria

• men and women,
• aged more than 18,
• non smokers for two years or longer, less than 10 pack/years smoking history,
• physician-diagnosed asthma,
• uncontrolled asthma with Asthma control test (ACT) < 18,
• historical of FEV1 reversibility,
• daily inhaled steroids treatment by at least 2000microg eq beclomethasone,
• Forced expiratory volume in 1 second (FEV1) > 50% predicted value

Exclusion criteria

• other chronic pulmonary disease,
• vocal cord dysfunction,
• pregnancy,
• Participation in another interventional research trial,
• unable to provide consent,
• asthma exacerbation within the last 4 weeks