Prevalence of Hyperventilation Syndrome in Difficult Asthma

Overview

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.

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.