Prevalence of Hyperventilation Syndrome in Difficult Asthma

Most of asthmatics patients remain uncontrolled despite an inhaled steroids treatment. Chronic hyperventilation syndrome (also called Idiopathic Hyperventilation) occurs in 20 to 40% of asthmatic patients. The purpose of the study is to assess the prevalence of chronic hyperventilation syndrome in a specific population of difficult-to-treat asthmatics patients, those who receive daily high doses of inhaled steroids (≥ 1000 µg of fluticasone with an additional treatment by a long-acting beta 2-agonist (LABA) and who remain uncontrolled (Asthma control test (ACT) \< 18). We plan to realize a systematic assessment of the diagnosis of chronic hyperventilation syndrome with the Nijmegen questionnaire, blood gases at rest, hyperventilation testing and Cardiopulmonary Exercise Testing(CPET). We also will collect demographic information as well as information about asthma history, asthma control and treatment.