Bronchial thermoplasty reduces gas trapping in severe asthma

BMC Pulmonary Medicine

David LangtonAlvin IngKim BennettsWei WangClaude FarahMatthew PetersVirginia Plummer and Francis Thien

Open Peer Review reports



In randomized controlled trials, bronchial thermoplasty (BT) has been proven to reduce symptoms in severe asthma, but the mechanisms by which this is achieved are uncertain as most studies have shown no improvement in spirometry. We postulated that BT might improve lung mechanics by altering airway resistance in the small airways of the lung in ways not measured by FEV1. This study aimed to evaluate changes in measures of gas trapping by body plethysmography.


A prospective cohort of 32 consecutive patients with severe asthma who were listed for BT at two Australian university hospitals were evaluated at three time points, namely baseline, and then 6 weeks and 6 months post completion of all procedures. At each evaluation, medication usage, symptom scores (Asthma Control Questionnaire, ACQ-5) and exacerbation history were obtained, and lung function was evaluated by (i) spirometry (ii) gas diffusion (KCO) and (iii) static lung volumes by body plethysmography.


ACQ-5 improved from 3.0 ± 0.8 at baseline to 1.5 ± 0.9 at 6 months (mean ± SD, p < 0.001, paired t-test). Daily salbutamol usage improved from 8.3 ± 5.6 to 3.5 ± 4.3 puffs per day (p < 0.001). Oral corticosteroid requiring exacerbations reduced from 2.5 ± 2.0 in the 6 months prior to BT, to 0.6 ± 1.3 in the 6 months after BT (p < 0.001). The mean baseline FEV1 was 57.8 ± 18.9%predicted, but no changes in any spirometric parameter were observed after BT. KCO was also unaltered by BT. A significant reduction in gas trapping was observed with Residual Volume (RV) falling from 146 ± 37% predicted at baseline to 136 ± 29%predicted 6 months after BT (p < 0.005). Significant improvements in TLC and FRC were also observed. These changes were evident at the 6 week time period and maintained at 6 months. The change in RV was inversely correlated with the baseline FEV1 (r = 0.572, p = 0.001), and in patients with a baseline FEV1 of < 60%predicted, the RV/TLC ratio fell by 6.5 ± 8.9%.


Bronchial thermoplasty improves gas trapping and this effect is greatest in the most severely obstructed patients. The improvement may relate to changes in the mechanical properties of small airways that are not measured with spirometry.

Download PDF 

(You must be logged in to add and reply comments)

Interasma on Twitter

Interasma Interasma - CME:Unlocking the Door to Asthma Control: Key Factors for Therapy Selection and Medication Management
Interasma RT @EAACI_HQ: Read this article! RNA‐specific toll-like receptors #TLR are important in immunity against various pathogens but an inadequat…
Interasma RT @worldallergy: Top story: This Is Why Food Allergies Are on the Rise, According to Experts, see more https://t.c…
Interasma RT @worldallergy: WAO Tweeted Times - top stories by @ARIAGuideline, @Interasma
Interasma RT @worldallergy: Top story: POLLAR: Impact of air POLLution on Asthma and Rhinitis; a European Institute of Innovation and Technology Heal…

Editor: Juan C. Ivancevich, MD

Copyright © Interasma 2003-2017  •  Terms of Use  •  Privacy Policy  •  Contact Us  •  Sitemap

Powered by FREI SA