PT - JOURNAL ARTICLE AU - Ashwin Rajan AU - Kim Bennetts AU - David Langton TI - Plethysmography-derived gas trapping lacks utility in predicting response to bronchial thermoplasty AID - 10.1183/23120541.00690-2021 DP - 2022 Apr 01 TA - ERJ Open Research PG - 00690-2021 VI - 8 IP - 2 4099 - http://openres.ersjournals.com/content/8/2/00690-2021.short 4100 - http://openres.ersjournals.com/content/8/2/00690-2021.full SO - erjor2022 Apr 01; 8 AB - There is a paucity of literature on measurable baseline parameters predicting response and guiding selection for bronchial thermoplasty. This study examines whether baseline gas trapping, as assessed by plethysmography, is associated with a response to bronchial thermoplasty at 12 months.43 consecutive patients with severe asthma (mean±sd age 57.6±13.3 years) were evaluated at baseline and 12 months post bronchial thermoplasty. Data collected at both time points included spirometry, body plethysmography and four clinical outcome measures, namely Asthma Control Questionnaire (ACQ) score, annual exacerbation frequency, maintenance oral corticosteroid requirement and short-acting β-agonist use.At baseline, participants had severe airflow obstruction (forced expiratory volume in 1 s 49.1±15.8%) with marked gas trapping (residual volume (RV) 150.3±40.8%, RV/total lung capacity (TLC) 51.3±10.5%), poor symptom control (ACQ 3.3±1.0) and frequent exacerbations (median 4, interquartile range 8). 12 months after bronchial thermoplasty, significant improvements were observed in all four clinical outcome measures. However, baseline RV and RV/TLC were not significantly associated with changes in ACQ nor any other clinical outcome measure, and changes in RV and RV/TLC did not significantly correlate with a change in any clinical outcome measure.Plethysmography-derived gas trapping does not demonstrate utility in predicting response and guiding selection for bronchial thermoplasty. An improvement in gas trapping was not associated with positive clinical outcomes, suggesting that this may not be the dominant mode of action of bronchial thermoplasty in generating clinical improvement.This study examined whether measuring gas trapping by plethysmography could be used to predict response to bronchial thermoplasty; no association was found https://bit.ly/3tJN1X8