Bronchial Thermoplasty in Asthma
Reviewed By Allergy, Immunology & Inflammation Assembly
Submitted by
Rachel Taliercio, DO
Staff, Respiratory Institute
Cleveland Clinic Foundation
Cleveland, OH
Sumita Khatri
Staff, Respiratory Institute
Co-Director, Asthma Center
Cleveland Clinic Foundation
Cleveland, OH
Submit your comments to the author(s).
History
A 49 year old bank employee and never smoker presents to outpatient clinic for evaluation of asthma. She was first diagnosed with asthma as an adult at the age of 27. Since the diagnosis she has been on maintenance therapy and her asthma was well controlled in her late 20’s and early 30’s. During her mid 30’s her asthma got worse, daily symptoms were more frequent and there was increased use of short acting rescue medication. In her 40’s she started to miss work because of asthma and symptoms from a common cold will now linger for weeks. It is harder for her to identify triggers and her asthma is more unpredictable. She has flares requiring prednisone on average two to three times per year. She was hospitalized for an asthma exacerbation two years ago and her most recent ED visit for asthma was one year ago. She currently has daily symptoms of asthma and wakes up at least twice a night. There is daily use of rescue medication and she is breathless with mild exertion. Current therapy is high dose Advair diskus 500/50 one puff twice daily and Singulair. She was on Xolair therapy for a year and a half with no clinical benefit.
Physical Exam
The patient’s BMI was 34. BP 130/90, pulse 75 beats/minute and oxygen saturation 96% on room air. Nasal mucosa appeared mildly inflamed. Lungs were clear to auscultation and there was no clubbing.
Lab
Spirometry demonstrated a diminished FEV1/FVC ratio of62, FEV1 of 1.63L (56%), and FVC of 2.60 L (70%). On date of initial evaluation, her asthma control test was 7, very poorly controlled.
When to call asthma severe is an important distinction for both clinical and therapeutic reasons. The International ERS/ATS guidelines on the definition, evaluation and treatment of severe asthma were updated in 2014. The definition of severe asthma for patients ≥ 6 years of age requires at least one year of treatment with high dose ICS and LABA or leukotriene modifier/theophylline. Therapy with systemic corticosteroids (≥ 50% of days) and frequency of flares (2 or more) have the same timeline of one year. Therapy with biologic agents is not part of the criteria however the diagnosis of severe asthma is required for the use of most biologic agents. Urgent visits and missed days of work are commonly seen with severe asthma but not required for the diagnosis. Additional criteria include history of serious exacerbations (prior hospitalization, ICU admission, or need for mechanical ventilation in the prior year) and evidence of airflow obstruction (FEV1/FVC ratio below the lower limit of normal and FEV1 % predicted ≤ 80).
Most patients with severe asthma are on combination ICS/LABA therapy. There are currently only two combination ICS/LABA inhalers that meet the criteria for high dose inhaled steroids: Mometasone Furoate/Formoterol Fumarate 200/5 two puffs twice daily and Fluticasone propionate/Salmeterol 500/50 one puff twice daily. High dose budesonide is defined as a daily dose of ≥ 1600 µg (MDI or DPI).
Obstructive sleep apnea is a comorbidity of asthma and a contributing factor for uncontrolled asthma. Obesity is another important comorbidity and this patient should be counseled on the importance of diet modification and exercise. There is not strong evidence for the treatment of silent reflux in the management of asthma. Heartburn should only be treated if the patient is experiencing troublesome symptoms and/or complications. Methacholine challenge testing is indicated when the clinical history and/or pulmonary function testing is not entirely consistent with asthma. This patient’s clinical history is consistent with a diagnosis of asthma and supported by spirometry showing airflow obstruction and a positive bronchodilator response. Rhinosinusitis commonly coexists with asthma and contributes to a lack of control. Sinus imaging is generally pursued when patients report a history of frequent/recurrent sinusitis and/or nasal polyposis/anosmia. High resolution chest CT is usually reserved for patients with an atypical presentation.
While we currently do not have a formalized consensus opinion regarding candidacy for bronchial thermoplasty (BT), there are generally agreed upon guidelines. Patients eligible for treatment with Xolair should first undergo therapy for at least four months and, if there is no response or sub-optimal response to therapy, BT should be considered. Prior therapy with biologic agents is not a contraindication to the procedure. Comorbidities, such as sinus disease, should be evaluated for and treated prior to considering BT. The procedure can be pursued when confounding factors are controlled. There are currently no guidelines regarding BMI and eligibility however all patients should be able to safely undergo conscious sedation. Clinical trials involving BT have restricted the procedure to patients with a pack year history of ≤ 10. Pulmonary function testing should be stable and within 85% of baseline prior to the procedure. Guidelines propose eligible patients should have an FEV1 % predicted ≥ 60.
Studies on bronchial thermoplasty (BT) have shown a decrease in the frequency of severe exacerbations, emergency room visits, and missed days of work. There is no improvement in lung function post-procedure. There was no reduction in the daily use of rescue medication and patients should be counseled that controller therapy will still be a key part of maintaining asthma control. There is a risk of asthma exacerbation post-procedure and patients undergoing BT have a higher rate of hospitalization owing to this risk.
References
- Chung KF et al. Eur Respir J 2014; 43: 343-373.
- Sheshadri et al. Curr Allergy Asthma Ref (2014) 14:470.
- Castro et al. AJRCCM 2010; 181: 116-124.
- Wahidi and Kraft. AJRCCM 201; 185: 710-714.
