Bronchial Thermoplasty for Severe Asthma With Dynamic Hyperinflation (HEAT-SA)

Evaluation of the Efficiency of Bronchial Thermoplasty on Dynamic Hyperinflation in Uncontrolled Severe Asthma

Bronchial thermoplasty is a treatment for severe asthma that consist in decreasing the thickness of bronchial muscle by heat using a catheter inserted into the bronchi under direct vision with the help of an endoscope This treatment has shown efficacy on symptoms, quality of life and the number of exacerbations related to severe asthma. This clinical study evaluates the efficiency of this treatment on the dynamic hyperinflation phenomenon (worsening of bronchial obstruction during exercise in patients with asthma contributing to worsening shortness of breath).

Bronchial thermoplasty is a recently validated bronchoscopic technique for the management of severe asthma that treats smooth muscle by radiofrequency to reduce its thickness. This procedure leads to improved asthma control and quality of life, but also to decreased exacerbations frequency and number of emergencies hospitalizations. This treatment requires 3 procedures every 3 to 4 weeks. The pathophysiological mechanisms underlying its effectiveness need to be better understood for an improved selection of best candidates. In particular, there is a discrepancy between the improvement observed in symptoms (ACQ), quality of life (AQLQ) and the lack of improvement in forced expiratory volume in 1 second (FEV1). Investigator assume that this paradox is due to an efficiency appearing at effort, targeting dynamic hyperinflation phenomenon. The objective of this study is to evaluate the influence of bronchial thermoplasty on dynamic hyperinflation in severe asthma. The secondary objectives are to assess the effectiveness of bronchial thermoplasty (ACQ, AQLQ) in a selected population of patients with dynamic hyperinflation and to describe bronchial wall structural changes by probe-based confocal LASER endomicroscopy (pCLE).

Three sessions of bronchial thermoplasty are needed to treat patients. There will be 3 to 4 weeks between each procedure. Bronchial thermoplasty procedure is performed under general anesthesia. The medical device used in this research to achieve the thermoplasty is the Alair system (class IIb medical device ; Boston scientific) A confocal endomicroscopy will be conducted at the first and final session of thermoplasty. This examination involves analyzing and recording the structure of bronchi microscopy through a small catheter placed on the bronchus. Photographs of the bronchi will be realized.

A lung plethysmography will be used to patients to see evolution of dynamic hyperinflation after bronchial thermoplasty, defined as a decrease in inspiratory capacity by more than 500 ml during exercise. The plethysmography will be made before the first procedure and three months after the third procedure.

Description of structural modification of the bronchial wall by probe-based confocal LASER endomicroscopy (pCLE) induced by bronchial thermoplasty

Efficiency of bronchial thermoplasty on asthma control (ACQ) and quality of life (AQLQ) in a selected population of patients with severe asthma with dynamic hyperinflation.

Listing of thermoplasty complications (bronchitis, bronchospasm, exacerbation of asthma, hemoptysis, bronchiectasis) by medical staff

Inclusion Criteria: Severe asthma, uncontrolled despite optimal treatment according to GINA (global initiative for asthma) recommendations At least 2 exacerbations treated by systemic steroids in the last year FEV1 between 40 and 80% of predicted values and dynamic hyperinflation (defined as a decrease in inspiratory capacity by more than 500 ml during exercise) Exclusion Criteria: Current asthma exacerbation or respiratory infection History of exacerbation after bronchoscopy FEV1 < 40% of predicted values Oxygen saturation < 90% Contra-indications to ALAIR catheter system : pacemaker or other electronic implanted device Allergy to Remifentanyl or Propofol pregnancy; breastfeeding

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