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      Bronchial thermoplasty reduces airway resistance

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          Abstract

          Background

          The mechanism for symptomatic improvement after bronchial thermoplasty (BT) is unclear, since spirometry reveals little or no change. In this study, the effects of BT on airway resistance were examined using two independent techniques.

          Methods

          Eighteen consecutive patients, with severe asthma (57.6 ± 14.2 years) were evaluated by spirometry and plethysmography at three time points: (i) baseline, (ii) left lung treated but right lung untreated and (iii) 6 weeks after both lungs were treated with BT. At each assessment, total and specific airway resistance (Raw, sRaw) were measured. High resolution CT scans were undertaken at the first two assessments, and measurements of lobar volume, airway volume and airway resistance were made. The Asthma Control Questionnaire (ACQ) was administered at each assessment.

          Results

          The baseline ACQ score was 3.5 ± 0.9, and improved progressively to 1.8 ± 1.2 ( p < 0.01). At baseline, severe airflow obstruction was observed, FEV1 44.8 ± 13.7% predicted, together with gas trapping, and elevated Raw at 342 ± 173%predicted. Following BT, significant improvements in Raw and sRaw were observed, as well as a reduction in Residual Volume, increase in Vital Capacity and no change in FEV1. The change in Raw correlated with the change in ACQ ( r = 0.56, p < 0.05).

          CT scans demonstrated reduced airway volume at baseline, which correlated with the increased Raw determined by plethysmography ( p = − 0.536, p = < 0.05). Following BT, the airway volume increased in the treated lung, and this was accompanied by a significant reduction in CT-determined local airway resistance.

          Conclusion

          Symptomatic improvement after BT is mediated by increased airway volume and reduced airway resistance.

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          Most cited references24

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          Development and validation of a questionnaire to measure asthma control

          International guidelines on asthma management indicate that the primary goal of treatment should be optimum asthma control. The aim of this study was to develop and validate the Asthma Control Questionnaire (ACQ). The authors generated a list of all symptoms used to assess control and sent it to 100 asthma clinicians who were members of guidelines committees (18 countries). They scored each symptom for its importance in evaluating asthma control. From the 91 responses, the five highest scoring symptoms were selected for the ACQ. In addition, there is one question on beta2-agonist use and another on airway calibre (total questions=7). The ACQ was tested in a 9-week observational study of 50 adults with symptomatic asthma. The ACQ and other measures of asthma health status were assessed at baseline, 1, 5 and 9 weeks. In patients whose asthma was stable between clinic visits, reliability of the ACQ was high (intraclass correlation coefficient (ICC)=0.90). The questionnaire was very responsive to change in asthma control (p<0.0001). Cross-sectional and longitudinal validity were supported by correlations between the ACQ and other measures of asthma health status being close to a priori predictions. In conclusion, the Asthma Control Questionnaire has strong evaluative and discriminative properties and can be used with confidence to measure asthma control.
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            Effectiveness and safety of bronchial thermoplasty in the treatment of severe asthma: a multicenter, randomized, double-blind, sham-controlled clinical trial.

            Bronchial thermoplasty (BT) is a bronchoscopic procedure in which controlled thermal energy is applied to the airway wall to decrease smooth muscle. To evaluate the effectiveness and safety of BT versus a sham procedure in subjects with severe asthma who remain symptomatic despite treatment with high-dose inhaled corticosteroids and long-acting beta(2)-agonists. A total of 288 adult subjects (Intent-to-Treat [ITT]) randomized to BT or sham control underwent three bronchoscopy procedures. Primary outcome was the difference in Asthma Quality of Life Questionnaire (AQLQ) scores from baseline to average of 6, 9, and 12 months (integrated AQLQ). Adverse events and health care use were collected to assess safety. Statistical design and analysis of the primary endpoint was Bayesian. Target posterior probability of superiority (PPS) of BT over sham was 95%, except for the primary endpoint (96.4%). The improvement from baseline in the integrated AQLQ score was superior in the BT group compared with sham (BT, 1.35 +/- 1.10; sham, 1.16 +/- 1.23 [PPS, 96.0% ITT and 97.9% per protocol]). Seventy-nine percent of BT and 64% of sham subjects achieved changes in AQLQ of 0.5 or greater (PPS, 99.6%). Six percent more BT subjects were hospitalized in the treatment period (up to 6 wk after BT). In the posttreatment period (6-52 wk after BT), the BT group experienced fewer severe exacerbations, emergency department (ED) visits, and days missed from work/school compared with the sham group (PPS, 95.5, 99.9, and 99.3%, respectively). BT in subjects with severe asthma improves asthma-specific quality of life with a reduction in severe exacerbations and healthcare use in the posttreatment period. Clinical trial registered with www.clinialtrials.gov (NCT00231114).
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              Asthma control during the year after bronchial thermoplasty.

              Bronchial thermoplasty is a bronchoscopic procedure to reduce the mass of airway smooth muscle and attenuate bronchoconstriction. We examined the effect of bronchial thermoplasty on the control of moderate or severe persistent asthma. We randomly assigned 112 subjects who had been treated with inhaled corticosteroids and long-acting beta2-adrenergic agonists (LABA) and in whom asthma control was impaired when the LABA were withdrawn to either bronchial thermoplasty or a control group. The primary outcome was the frequency of mild exacerbations, calculated during three scheduled 2-week periods of abstinence from LABA at 3, 6, and 12 months. Airflow, airway responsiveness, asthma symptoms, the number of symptom-free days, use of rescue medication, and scores on the Asthma Quality of Life Questionnaire (AQLQ) and the Asthma Control Questionnaire (ACQ) were also assessed. The mean rate of mild exacerbations, as compared with baseline, was reduced in the bronchial-thermoplasty group but was unchanged in the control group (change in frequency per subject per week, -0.16+/-0.37 vs. 0.04+/-0.29; P=0.005). At 12 months, there were significantly greater improvements in the bronchial-thermoplasty group than in the control group in the morning peak expiratory flow (39.3+/-48.7 vs. 8.5+/-44.2 liters per minute), scores on the AQLQ (1.3+/-1.0 vs. 0.6+/-1.1) and ACQ (reduction, 1.2+/-1.0 vs. 0.5+/-1.0), the percentage of symptom-free days (40.6+/-39.7 vs. 17.0+/-37.9), and symptom scores (reduction, 1.9+/-2.1 vs. 0.7+/-2.5) while fewer puffs of rescue medication were required. Values for airway responsiveness and forced expiratory volume in 1 second did not differ significantly between the two groups. Adverse events immediately after treatment were more common in the bronchial-thermoplasty group than in the control group but were similar during the period from 6 weeks to 12 months after treatment. Bronchial thermoplasty in subjects with moderate or severe asthma results in an improvement in asthma control. (ClinicalTrials.gov number, NCT00214526 [ClinicalTrials.gov].). Copyright 2007 Massachusetts Medical Society.
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                Author and article information

                Contributors
                davidlangton@phcn.vic.gov.au
                KBennetts@phcn.vic.gov.au
                peter.noble@uwa.edu.au
                virginia.plummer@monash.edu
                frank.thien@monash.edu
                Journal
                Respir Res
                Respir. Res
                Respiratory Research
                BioMed Central (London )
                1465-9921
                1465-993X
                30 March 2020
                30 March 2020
                2020
                : 21
                : 76
                Affiliations
                [1 ]GRID grid.466993.7, ISNI 0000 0004 0436 2893, Department of Thoracic Medicine, Frankston Hospital, , Peninsula Health, ; 2 Hastings Road, Frankston, VIC 3199 Australia
                [2 ]GRID grid.1002.3, ISNI 0000 0004 1936 7857, Faculty of Medicine, Nursing and Health Sciences, , Monash University, ; Clayton, Victoria Australia
                [3 ]GRID grid.1012.2, ISNI 0000 0004 1936 7910, School of Human Sciences, , The University of Western Australia, ; Crawley, Western Australia Australia
                [4 ]GRID grid.414366.2, ISNI 0000 0004 0379 3501, Department of Respiratory Medicine, , Eastern Health, ; Box Hill, Victoria Australia
                Article
                1330
                10.1186/s12931-020-1330-5
                7106594
                32228586
                6094ae5d-d72a-40fc-bbc0-f7e078609e3b
                © The Author(s). 2020

                Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

                History
                : 30 December 2019
                : 27 February 2020
                Categories
                Research
                Custom metadata
                © The Author(s) 2020

                Respiratory medicine
                bronchial thermoplasty,asthma,airway resistance,imaging
                Respiratory medicine
                bronchial thermoplasty, asthma, airway resistance, imaging

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