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Foo CT, Donovan GM, Thien F, Langton D, Noble PB. Bronchial Thermoplasty Improves Ventilation Heterogeneity Measured by Functional Respiratory Imaging in Severe Asthma. J Asthma Allergy 2024; 17:399-409. [PMID: 38681236 PMCID: PMC11048211 DOI: 10.2147/jaa.s454951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/22/2024] [Indexed: 05/01/2024] Open
Abstract
Purpose Bronchial thermoplasty (BT) is a bronchoscopic intervention for the treatment of severe asthma. Despite demonstrated symptomatic benefit, the underlying mechanisms by which this is achieved remain uncertain. We hypothesize that the effects of BT are driven by improvements in ventilation heterogeneity as assessed using functional respiratory imaging (FRI). Patient and Methods Eighteen consecutive patients with severe asthma who underwent clinically indicated BT were recruited. Patients were assessed at baseline, 4-week after treatment of the left lung, and 12-month after treatment of the right lung. Data collected included short-acting beta-agonist (SABA) and oral prednisolone (OCS) use, asthma control questionnaire (ACQ-5) and exacerbation history. Patients also underwent lung function tests and chest computed tomography. Ventilation parameters including interquartile distance (IQD; measure of ventilation heterogeneity) were derived using FRI. Results 12 months after BT, significant improvements were seen in SABA and OCS use, ACQ-5, and number of OCS-requiring exacerbations. Apart from pre-bronchodilator FEV1, no other significant changes were observed in lung function. Ventilation heterogeneity significantly improved after treatment of the left lung (0.18 ± 0.04 vs 0.20 ± 0.04, p=0.045), with treatment effect persisting up to 12 months later (0.18 ± 0.05 vs 0.20 ± 0.04, p=0.028). Ventilation heterogeneity also improved after treatment of the right lung, although this did not reach statistical significance (0.18 ± 0.05 vs 0.19 ± 0.04, p=0.06). Conclusion Clinical benefits after BT are accompanied by improvements in ventilation heterogeneity, advancing our understanding of its mechanism of action. Beyond BT, FRI has the potential to be expanded into other clinical applications.
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Affiliation(s)
- Chuan T Foo
- Department of Respiratory Medicine, Eastern Health, Melbourne, VIC, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - Graham M Donovan
- Department of Mathematics, University of Auckland, Auckland, New Zealand
| | - Francis Thien
- Department of Respiratory Medicine, Eastern Health, Melbourne, VIC, Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - David Langton
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
- Department of Thoracic Medicine, Peninsula Health, Frankston, VIC, Australia
| | - Peter B Noble
- School of Human Sciences, The University of Western Australia, Crawley, WA, Australia
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2
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Henry C, Biardel S, Boucher M, Godbout K, Chakir J, Côté A, Laviolette M, Bossé Y. Bronchial thermoplasty attenuates bronchodilator responsiveness. Respir Med 2023; 217:107340. [PMID: 37422022 DOI: 10.1016/j.rmed.2023.107340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/31/2023] [Accepted: 06/25/2023] [Indexed: 07/10/2023]
Abstract
INTRODUCTION Bronchial thermoplasty is an effective intervention to improve respiratory symptoms and to reduce the rate of exacerbations in uncontrolled severe asthma. A reduction in airway smooth muscle is arguably the most widely discussed mechanisms accounting for these clinical benefits. Yet, this smooth muscle reduction should also translate into an impaired response to bronchodilator drugs. This study was designed to address this question. METHODS Eight patients with clinical indication for thermoplasty were studied. They were uncontrolled severe asthmatics despite optimal environmental control, treatment of comorbidities, and the use of high-dose inhaled corticosteroids and long-acting β2-agonists. Lung function measured by spirometry and respiratory mechanics measured by oscillometry were examined pre- and post-bronchodilator (salbutamol, 400 μg), both before and at least 1 year after thermoplasty. RESULTS Consistent with previous studies, thermoplasty yielded no benefits in terms of baseline lung function and respiratory mechanics, despite improving symptoms based on two asthma questionnaires (ACQ-5 and ACT-5). The response to salbutamol was also not affected by thermoplasty based on spirometric readouts, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio. However, a significant interaction was observed between thermoplasty and salbutamol for two oscillometric readouts, namely reactance at 5 Hz (Xrs5) and reactance area (Ax), showing an attenuated response to salbutamol after thermoplasty. CONCLUSIONS Thermoplasty attenuates the response to a bronchodilator. We argue that this result is a physiological proof of therapeutic efficacy, consistent with the well-described effect of thermoplasty in reducing the amount of airway smooth muscle.
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Affiliation(s)
- Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Sabrina Biardel
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Krystelle Godbout
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Jamila Chakir
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Andréanne Côté
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Michel Laviolette
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ) - Université Laval, Québec, Canada.
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3
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Liao X, Gao S, Xie F, Wang K, Wu X, Wu Y, Gao W, Wang M, Sun J, Liu D, Xu W, Li Q. An underlying mechanism behind interventional pulmonology techniques for refractory asthma treatment: Neuro-immunity crosstalk. Heliyon 2023; 9:e20797. [PMID: 37867902 PMCID: PMC10585236 DOI: 10.1016/j.heliyon.2023.e20797] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 09/11/2023] [Accepted: 10/06/2023] [Indexed: 10/24/2023] Open
Abstract
Asthma is a common disease that seriously threatens public health. With significant developments in bronchoscopy, different interventional pulmonology techniques for refractory asthma treatment have been developed. These technologies achieve therapeutic purposes by targeting diverse aspects of asthma pathophysiology. However, even though these newer techniques have shown appreciable clinical effects, their differences in mechanisms and mutual commonalities still deserve to be carefully explored. Therefore, in this review, we summarized the potential mechanisms of bronchial thermoplasty, targeted lung denervation, and cryoablation, and analyzed the relationship between these different methods. Based on available evidence, we speculated that the main pathway of chronic airway inflammation and other pathophysiologic processes in asthma is sensory nerve-related neurotransmitter release that forms a "neuro-immunity crosstalk" and amplifies airway neurogenic inflammation. The mechanism of completely blocking neuro-immunity crosstalk through dual-ablation of both efferent and afferent fibers may have a leading role in the clinical efficacy of interventional pulmonology in the treatment of asthma and deserves further investigation.
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Affiliation(s)
- Ximing Liao
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Shaoyong Gao
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Fengyang Xie
- Department of Hematology, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Kun Wang
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xiaodong Wu
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yin Wu
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Wei Gao
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Muyun Wang
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Jiaxing Sun
- Department of Respiratory and Critical Care Medicine, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Dongchen Liu
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Shantou University Medical College, Shantou, 515000, China
| | - Wujian Xu
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Qiang Li
- Department of Respiratory and Critical Care Medicine, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
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4
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Li A, Lee P. Which Endoscopic Procedure to Use and in What Patient? Valves, Coils, Foam, and Heat in COPD and Asthma. Pulm Ther 2022; 9:49-69. [PMID: 36534323 PMCID: PMC9931990 DOI: 10.1007/s41030-022-00208-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 11/10/2022] [Indexed: 12/23/2022] Open
Abstract
Despite the latest developments in therapeutic agents targeting airway endotypes, a significant proportion of patients with asthma and chronic obstructive pulmonary disease (COPD) remain symptomatic. Endoscopic therapies have a complementary role in the management of these airway diseases. The sustained efficacy of bronchial thermoplasty (BT) among patients with asthma over 10 years has been encouraging, as it has been shown to improve symptom control and reduce hospital admissions and exacerbations. Studies suggest that BT helps ameliorate airway inflammation and reduce airway smooth muscle thickness. While studies suggest that it is as effective as biologic agents, its role in the management of severe asthma has yet to be clearly defined and GINA 2022 still suggests limiting its use to patients with characteristics of the various populations studied. Conversely, bronchoscopic lung volume reduction has shown promise among patients with advanced COPD. Rigorous patient selection is important. Patients with minimal collateral ventilation (CV) and higher heterogeneity index have shown to benefit the most from endobronchial valve (EBV) therapy. For those with ongoing CV, endobronchial coils would be more appropriate. Both therapeutic modalities have demonstrated improved quality of life, effort tolerance, and lung function indices among appropriately selected patients. The emerging evidence suggests that endoscopic procedures among airway disease still have a substantial role to play despite the development of new therapeutic options.
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Affiliation(s)
- Andrew Li
- Respiratory and Critical Care Medicine, National University Hospital, 1E Kent Ridge Road, Singapore, 119228, Singapore. .,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. .,Respiratory Service, Department of Medicine, Woodlands Health, Singapore, Singapore.
| | - Pyng Lee
- Respiratory and Critical Care Medicine, National University Hospital, 1E Kent Ridge Road, Singapore, 119228 Singapore ,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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5
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Hashmi MD, Khan A, Shafiq M. Bronchial thermoplasty: State of the art. Respirology 2022; 27:720-729. [PMID: 35692074 DOI: 10.1111/resp.14312] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/30/2022] [Indexed: 11/30/2022]
Abstract
Since the publication of a sham-controlled, randomized trial (AIR2) and subsequent marketing approval by the US Food and Drug Administration, we have significantly advanced our understanding of bronchial thermoplasty (BT)'s scientific basis, long-term safety, clinical efficacy and cost-effectiveness. In particular, the last 2 years have witnessed multiple research publications on several of these counts. In this review, we critically appraise our evolving understanding of BT's biologic underpinnings and clinical impact, offer an evidence-based patient workflow guide for the busy pulmonologist and highlight both current challenges as well as potential solutions for the researcher and the clinician.
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Affiliation(s)
- Muhammad Daniyal Hashmi
- Division of Pulmonary and Critical Care Medicine, Henry Ford Hospital, Wayne State University, Detroit, Michigan, USA
| | - Asad Khan
- Division of Pulmonary and Critical Care Medicine, University of Massachusetts Chan Medical School-Baystate, Springfield, Massachusetts, USA
| | - Majid Shafiq
- Division of Pulmonary and Critical Care Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, USA
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6
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Rajan A, Bennetts K, Langton D. Plethysmography Derived Gas Trapping Lacks Utility in Predicting Response to Bronchial Thermoplasty. ERJ Open Res 2022; 8:00690-2021. [PMID: 35539441 PMCID: PMC9081540 DOI: 10.1183/23120541.00690-2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 03/04/2022] [Indexed: 12/03/2022] Open
Abstract
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 foundhttps://bit.ly/3tJN1X8
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7
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Papakonstantinou E, Koletsa T, Zhou L, Fang L, Roth M, Karakioulaki M, Savic S, Grize L, Tamm M, Stolz D. Bronchial thermoplasty in asthma: an exploratory histopathological evaluation in distinct asthma endotypes/phenotypes. Respir Res 2021; 22:186. [PMID: 34183014 PMCID: PMC8240300 DOI: 10.1186/s12931-021-01774-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/07/2021] [Indexed: 11/24/2022] Open
Abstract
Background Bronchial thermoplasty regulates structural abnormalities involved in airway narrowing in asthma. In the present study we aimed to investigate the effect of bronchial thermoplasty on histopathological bronchial structures in distinct asthma endotypes/phenotypes.
Methods Endobronchial biopsies (n = 450) were collected from 30 patients with severe uncontrolled asthma before bronchial thermoplasty and after 3 sequential bronchial thermoplasties. Patients were classified based on blood eosinophils, atopy, allergy and smoke exposure. Tissue sections were assessed for histopathological parameters and expression of heat-shock proteins and glucocorticoid receptor. Proliferating cells were determined by Ki67-staining. Results In all patients, bronchial thermoplasty improved asthma control (p < 0.001), reduced airway smooth muscle (p = 0.014) and increased proliferative (Ki67 +) epithelial cells (p = 0.014). After bronchial thermoplasty, airway smooth muscle decreased predominantly in patients with T2 high asthma endotype. Epithelial cell proliferation was increased after bronchial thermoplasty in patients with low blood eosinophils (p = 0.016), patients with no allergy (p = 0.028) and patients without smoke exposure (p = 0.034).
In all patients, bronchial thermoplasty increased the expression of glucocorticoid receptor in epithelial cells (p = 0.018) and subepithelial mesenchymal cells (p = 0.033) and the translocation of glucocorticoid receptor in the nucleus (p = 0.036). Furthermore, bronchial thermoplasty increased the expression of heat shock protein-70 (p = 0.002) and heat shock protein-90 (p = 0.001) in epithelial cells and decreased the expression of heat shock protein-70 (p = 0.009) and heat shock protein-90 (p = 0.002) in subepithelial mesenchymal cells. The effect of bronchial thermoplasty on the expression of heat shock proteins -70 and -90 was distinctive across different asthma endotypes/phenotypes. Conclusions Bronchial thermoplasty leads to a diminishment of airway smooth muscle, to epithelial cell regeneration, increased expression and activation of glucocorticoid receptor in the airways and increased expression of heat shock proteins in the epithelium. Histopathological effects appear to be distinct in different endotypes/phenotypes indicating that the beneficial effects of bronchial thermoplasty are achieved by diverse molecular targets associated with asthma endotypes/phenotypes. Supplementary Information The online version contains supplementary material available at 10.1186/s12931-021-01774-0.
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Affiliation(s)
- Eleni Papakonstantinou
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland.,Laboratory of Pharmacology, Faculty of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Triantafyllia Koletsa
- Department of Pathology, Faculty of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Liang Zhou
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Lei Fang
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Michael Roth
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Meropi Karakioulaki
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Spasenija Savic
- Department of Pathology, University Hospital of Basel, Basel, Switzerland
| | - Leticia Grize
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Michael Tamm
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland
| | - Daiana Stolz
- Clinic of Respiratory Medicine and Pulmonary Cell Research, University Hospital of Basel and Department of Biomedicine, University of Basel, Petersgraben 4, 4031, Basel, Switzerland.
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8
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Dokuni R, Kobayashi K, Ohno Y, Nagano T, Tamura D, Umezawa K, Katsurada N, Nakata K, Yamamoto M, Tachihara M, Kamiryo H, Nishimura Y. Effect of Bronchial Thermoplasty on Air Trapping Assessed by Xenon Ventilation Computed Tomography. Intern Med 2021; 60:2027-2032. [PMID: 34193773 PMCID: PMC8313928 DOI: 10.2169/internalmedicine.6493-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Objective Bronchial thermoplasty (BT) is a bronchoscopic procedure for patients with severe asthma. Although it has been suggested that BT works by reducing airway smooth muscle, the detailed mechanism underlying its effects is still unknown. Methods We performed xenon ventilation computed tomography (Xe-CT) before each BT procedure and six weeks after the third treatment to assess the improvement in lung ventilation at each separate lung region. The air trapping index in each lobe was defined as the mean trapping value (0: none, 1: mild, 2: moderate, and 3: severe) of the included segments. Patients and Materials Four patients were included. Results Asthma symptoms were improved after BT. The comparison of the scores at baseline with those after the third treatment showed that the air trapping index was improved in both the treated and untreated regions. However, neither the pulmonary function nor the exhaled nitric oxide was improved. Conclusion Using Xe-CT, we successfully evaluated the air trapping in patients who underwent BT. The improvement in asthma symptoms by BT may be related to the amelioration of peripheral lung ventilation in both the treated and untreated regions.
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Affiliation(s)
- Ryota Dokuni
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Kazuyuki Kobayashi
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Yoshiharu Ohno
- Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe University Graduate School of Medicine, Japan
| | - Tatsuya Nagano
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Daisuke Tamura
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Kanoko Umezawa
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Naoko Katsurada
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Kyosuke Nakata
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Masatsugu Yamamoto
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Motoko Tachihara
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Hiroshi Kamiryo
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
| | - Yoshihiro Nishimura
- Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Japan
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9
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Langton D, Banks C, Noble PB, Plummer V, Thien F, Donovan GM. The effect of bronchial thermoplasty on airway volume measured 12 months post-procedure. ERJ Open Res 2020; 6:00300-2020. [PMID: 33263039 PMCID: PMC7682672 DOI: 10.1183/23120541.00300-2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/21/2020] [Indexed: 11/05/2022] Open
Abstract
Bronchial thermoplasty induces atrophy of the airway smooth muscle layer, but the mechanism whereby this improves patient health is unclear. In this study, we use computed tomography (CT) to evaluate the effects of bronchial thermoplasty on airway volume 12 months post-procedure. 10 consecutive patients with severe asthma were evaluated at baseline by the Asthma Control Questionnaire (ACQ), and high-resolution CT at total lung capacity (TLC) and functional residual capacity (FRC). The CT protocol was repeated 4 weeks after the left lung had been treated by bronchial thermoplasty, but prior to right lung treatment, and then again 12 months after both lungs were treated. The CT data were also used to model the implications of including the right middle lobe (RML) in the treatment field. The mean patient age was 62.7±7.7 years and forced expiratory volume in 1 s (FEV1) 42.9±11.5% predicted. 12 months post-bronchial-thermoplasty, the ACQ improved, from 3.4±1.0 to 1.5±0.9 (p=0.001), as did the frequency of oral steroid-requiring exacerbations (p=0.008). The total airway volume increased 12 months after bronchial thermoplasty in both the TLC (p=0.03) and the FRC scans (p=0.02). No change in airway volume was observed in the untreated central airways. In the bronchial thermoplasty-treated distal airways, increases in airway volume of 38.4±31.8% at TLC (p=0.03) and 30.0±24.8% at FRC (p=0.01) were observed. The change in distal airway volume was correlated with the improvement in ACQ (r=-0.71, p=0.02). Modelling outputs demonstrated that treating the RML conferred no additional benefit. Bronchial thermoplasty induces long-term increases in airway volume, which correlate with symptomatic improvement.
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Affiliation(s)
- David Langton
- Dept of Thoracic Medicine, Frankston Hospital, Peninsula Health, Melbourne, Victoria, Australia.,Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Ceri Banks
- Dept of Thoracic Medicine, Frankston Hospital, Peninsula Health, Melbourne, Victoria, Australia
| | - Peter B Noble
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Virginia Plummer
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Francis Thien
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia.,Dept of Respiratory Medicine, Eastern Health, Melbourne, Victoria, Australia
| | - Graham M Donovan
- Dept of Mathematics, University of Auckland, Auckland, New Zealand
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10
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Langton D, Lee P. Bronchial thermoplasty: Redefining its role. Respirology 2020; 25:981-986. [PMID: 32567121 DOI: 10.1111/resp.13887] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 04/10/2020] [Accepted: 04/29/2020] [Indexed: 02/01/2023]
Abstract
In this review, we trace (i) the origins of bronchial thermoplasty, (ii) the development of a solid evidence base for efficacy and safety, (iii) the emerging understanding of the pathophysiological mechanisms of action and (iv) the place in therapy today. Future challenges are then discussed.
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Affiliation(s)
- David Langton
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, Melbourne, VIC, Australia.,Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - Pyng Lee
- Division of Respiratory and Critical Care Medicine, National University Hospital, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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11
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Langton D, Bennetts K, Noble P, Plummer V, Thien F. Bronchial thermoplasty reduces airway resistance. Respir Res 2020; 21:76. [PMID: 32228586 PMCID: PMC7106594 DOI: 10.1186/s12931-020-1330-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 02/27/2020] [Indexed: 12/17/2022] Open
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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Affiliation(s)
- David Langton
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, 2 Hastings Road, Frankston, VIC 3199 Australia
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria Australia
| | - Kim Bennetts
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, 2 Hastings Road, Frankston, VIC 3199 Australia
| | - Peter Noble
- School of Human Sciences, The University of Western Australia, Crawley, Western Australia Australia
| | - Virginia Plummer
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria Australia
| | - Francis Thien
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria Australia
- Department of Respiratory Medicine, Eastern Health, Box Hill, Victoria Australia
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12
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Goorsenberg AWM, d'Hooghe JNS, Slats AM, van den Aardweg JG, Annema JT, Bonta PI. Resistance of the respiratory system measured with forced oscillation technique (FOT) correlates with bronchial thermoplasty response. Respir Res 2020; 21:52. [PMID: 32050956 PMCID: PMC7017531 DOI: 10.1186/s12931-020-1313-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/04/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Bronchial Thermoplasty (BT) is an endoscopic treatment for severe asthma using radiofrequency energy to target airway remodeling including smooth muscle. The correlation of pulmonary function tests and BT response are largely unknown. Forced Oscillation Technique (FOT) is an effort-independent technique to assess respiratory resistance (Rrs) by using pressure oscillations including small airways. AIM To investigate the effect of BT on pulmonary function, assessed by spirometry, bodyplethysmography and FOT and explore associations between pulmonary function parameters and BT treatment response. METHODS Severe asthma patients recruited to the TASMA trial were analyzed in this observational cohort study. Spirometry, bodyplethysmography and FOT measurements were performed before and 6 months after BT. Asthma questionnaires (AQLQ/ACQ-6) were used to assess treatment response. RESULTS Twenty-four patients were analyzed. AQLQ and ACQ improved significantly 6 months after BT (AQLQ 4.15 (±0.96) to 4.90 (±1.14) and ACQ 2.64 (±0.60) to 2.11 (±1.04), p = 0.004 and p = 0.02 respectively). Pulmonary function parameters remained stable. Improvement in FEV1 correlated with AQLQ change (r = 0.45 p = 0.03). Lower respiratory resistance (Rrs) at baseline (both 5 Hz and 19 Hz) significantly correlated to AQLQ improvement (r = - 0.52 and r = - 0.53 respectively, p = 0.01 (both)). Borderline significant correlations with ACQ improvement were found (r = 0.30 p = 0.16 for 5 Hz and r = 0.41 p = 0.05 for 19 Hz). CONCLUSION Pulmonary function remained stable after BT. Improvement in FEV1 correlated with asthma questionnaires improvement including AQLQ. Lower FOT-measured respiratory resistance at baseline was associated with favorable BT response, which might reflect targeting of larger airways with BT. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT02225392; Registered 26 August 2014.
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Affiliation(s)
- Annika W M Goorsenberg
- Department of Respiratory Medicine. F5-144, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Julia N S d'Hooghe
- Department of Respiratory Medicine. F5-144, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Annelies M Slats
- Department of Respiratory Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Joost G van den Aardweg
- Department of Respiratory Medicine. F5-144, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Jouke T Annema
- Department of Respiratory Medicine. F5-144, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Peter I Bonta
- Department of Respiratory Medicine. F5-144, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
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13
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Sugiyama H, Iikura M, Ishii S, Hojo M. Treatment for intractable asthma: bronchial thermoplasty. Glob Health Med 2019; 1:95-100. [PMID: 33330762 DOI: 10.35772/ghm.2019.01027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/18/2019] [Accepted: 11/25/2019] [Indexed: 01/01/2023]
Abstract
Bronchial Thermoplasty (BT) is an epoch-making treatment that reduces bronchial smooth muscle by using a bronchoscope to reach the basket catheter to the bronchus and directing high-frequency current directly into the bronchi. In GINA Guidelines 2019, BT is considered to be additional treatment at Step V (the most severe), and the evidence level is B. The Japanese guidelines (JGL) also added BT as a treatment for Step 4, but it is reserved because there are still unclear points regarding long-term efficacy and safety. In Japan, as of April 1, 2019, 672 treatments were performed at 123 institutions nationwide. The average age of patients was 54.1 years, but 84 cases were over 70 years old. The average value of %FEV1 was 78.2%, but there were 94 cases less than 60%. There were 32 cases that underwent BT treatment at our institution. Of them, 12 cases with progress up to one year later could be observed. The average age was 56.1 years old, and each of 6 men and women had a %FEV1 of 70.5%. One year later, AQLQ and %FEV1 improved, and the number of exacerbations decreased, but exhaled NO values increased. %FEV1 improvement might be due to poorer lung function (70.5% vs. 77.8%) and more BT activation (average 1.28 times AIR2) compared to the AIR2 trial. In terms of improvement in %FEV1, patients with moderate obstructive disorder from 50 to 80% responded well after BT treatment. In the near future, various new antibody preparations such as IL-4 / 13 antibody and anti-TSLP antibody are expected to be promoted. Therefore, we first consider whether these antibody preparations can be applied to patients with refractory asthma. We consider that BT is indicated only when there is no indication or no expected effect of antibody preparations. In other words, BT treatment is the last resort of intractable asthma, and it is the duty of medical professionals involved in BT treatment to be able to advocate when it is best to give BT to such patients.
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Affiliation(s)
- Haruhito Sugiyama
- Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan
| | - Motoyasu Iikura
- Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan
| | - Satoru Ishii
- Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan
| | - Masayuki Hojo
- Department of Respiratory Medicine, National Center for Global Health and Medicine, Tokyo, Japan
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14
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Thomson NC. Recent Developments In Bronchial Thermoplasty For Severe Asthma. J Asthma Allergy 2019; 12:375-387. [PMID: 31819539 PMCID: PMC6875488 DOI: 10.2147/jaa.s200912] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 10/30/2019] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Bronchial thermoplasty is approved in many countries worldwide as a non-pharmacological treatment for severe asthma. This review summarizes recent publications on the selection of patients with severe asthma for bronchial thermoplasty, predictors of a beneficial response and developments in the procedure and discusses specific issues about bronchial thermoplasty including effectiveness in clinical practice, mechanism of action, cost-effectiveness, and place in management. RESULTS Bronchial thermoplasty is a treatment option for patients with severe asthma after assessment and management of causes of difficult-to-control asthma, such as nonadherence, poor inhaler technique, comorbidities, under treatment, and other behavioral factors. Patients treated with bronchial thermoplasty in clinical practice have worse baseline characteristics and comparable clinical outcomes to clinical trial data. Bronchial thermoplasty causes a reduction in airway smooth muscle mass although it is uncertain whether this effect explains its efficacy since other mechanisms of action may be relevant, such as alterations in airway epithelial, gland, and/or nerve function; improvements in small airway function; or a placebo effect. The cost-effectiveness of bronchial thermoplasty is greater in countries where the costs of hospitalization and emergency department are high. The place of bronchial thermoplasty in the management of severe asthma is not certain, although some experts propose that bronchial thermoplasty should be considered for patients with severe asthma associated with non-type 2 inflammation or who fail to respond favorably to biologic therapies targeting type 2 inflammation. CONCLUSION Bronchial thermoplasty is a modestly effective treatment for severe asthma after assessment and management of causes of difficult-to-control asthma. Asthma morbidity increases during and shortly after treatment. Follow-up studies provide reassurance on the long-term safety of the procedure. Uncertainties remain about predictors of response, mechanism(s) of action, and place in management of severe asthma.
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Affiliation(s)
- Neil C Thomson
- Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, UK
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Langton D, Wang W, Sha J, Ing A, Fielding D, Hersch N, Plummer V, Thien F. Predicting the Response to Bronchial Thermoplasty. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY-IN PRACTICE 2019; 8:1253-1260.e2. [PMID: 31712191 DOI: 10.1016/j.jaip.2019.10.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 10/06/2019] [Accepted: 10/22/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND Although it is established that not all patients respond to bronchial thermoplasty (BT), the factors that predict response/nonresponse are largely unknown. OBJECTIVES To identify baseline factors that predict clinical response. METHODS The records of 77 consecutive patients entered into the Australian Bronchial Thermoplasty Registry were examined for baseline clinical characteristics, and outcomes measured at 6 and 12 months after BT, such as change in the Asthma Control Questionnaire (ACQ) score, exacerbation frequency, the requirement for short-acting beta-2 agonist (SABA) medication and oral corticosteroids, and improvement in spirometry. RESULTS This was a cohort of patients with severe asthma: aged 57.7 ± 11.4 years, 57.1% females, 53.2% of patients taking maintenance oral steroids, 43% having been treated with an mAb, mean FEV1 of 55.8% ± 19.8% predicted. RESULTS BT resulted in an improvement in the ACQ score from 3.2 ± 1.0 at baseline to 1.6 ± 1.1 at 6 months (P < .001). Exacerbation frequency in the previous 6 months reduced from 3.7 ± 3.3 to 0.7 ± 1.2 (P < .001). SABA requirement reduced from 9.3 ± 7.1 puffs/d to 3.5 ± 6.0 (P < .001), and 48.8% of patients were weaned completely off oral steroids. A significant improvement in FEV1 was observed. Using multiple linear regression models, baseline ACQ score strongly predicted improvement in ACQ score (P < .001). Patients with an exacerbation frequency greater than twice in the previous 6 months showed the greatest reduction in exacerbations (-5.3 ± 2.8; P < .001). Patients using more than 10 puffs/d of SABA experienced the greatest reduction in SABA requirement (-12.4 ± 10.5 puffs, P < .001). CONCLUSIONS The most severely afflicted patients had the greatest improvements in ACQ score, exacerbation frequency, and medication requirement.
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Affiliation(s)
- David Langton
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, Frankston, VIC, Australia; Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia.
| | - Wei Wang
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Joy Sha
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, Frankston, VIC, Australia
| | - Alvin Ing
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - David Fielding
- Department of Thoracic Medicine, Royal Brisbane and Women's Hospital, Herston, QLD, Australia
| | - Nicole Hersch
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Virginia Plummer
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, Frankston, VIC, Australia; Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia
| | - Francis Thien
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC, Australia; Department of Respiratory Medicine, Eastern Health, Box Hill, VIC, Australia
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16
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Langton D, Sloan G, Banks C, Bennetts K, Plummer V, Thien F. Bronchial thermoplasty increases airway volume measured by functional respiratory imaging. Respir Res 2019; 20:157. [PMID: 31311604 PMCID: PMC6636001 DOI: 10.1186/s12931-019-1132-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 07/10/2019] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The purpose of this study was to use CT scanning with computational fluid dynamics to evaluate the mechanisms by which Bronchial Thermoplasty (BT) improves asthmatic symptoms. METHODS The study was conducted in a university teaching hospital, experienced in performing BT. Imaging studies were performed before, and after, BT of the left lung, and prior to treatment of the right lung, which therefore acted as a control. On each occasion, two high-resolution CT scans were performed, one at full inspiration (TLC) and the other at Functional Residual Capacity (FRC). The study protocol was offered to 10 patients, all of whom met the definition of severe asthma, despite high dose inhaled corticosteroids and dual long acting bronchodilators. RESULTS Significant increases in airway luminal volume were observed on the treated side, compared with control, at both full inspiration (by 27%) and at FRC (by 17%). The ratio of distal airway volume to lung volume significantly increased on the treated side. The change in airway volume with inspiration from FRC increased by 48% on the treated side compared to 5% in the control lung, suggesting treatment increased airway distensibility. No effect was observed on airway wall thickness, nor air trapping. There was a trend towards correlation between the improvement in airway volume at TLC and improvement in symptoms. CONCLUSION This study demonstrates that BT increases the luminal airway volume on the treated side compared to the control lung. We suggest that this is an important link between the airway smooth muscle atrophy demonstrated pathologically, and the improvement in symptoms observed clinically.
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Affiliation(s)
- D Langton
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, 2 Hastings Road, Frankston, VIC, 3199, Australia. .,Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Vic, Australia.
| | - G Sloan
- Department of Medical Imaging, Frankston Hospital, Peninsula Health, Frankston, Vic, Australia
| | - C Banks
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, 2 Hastings Road, Frankston, VIC, 3199, Australia
| | - K Bennetts
- Department of Thoracic Medicine, Frankston Hospital, Peninsula Health, 2 Hastings Road, Frankston, VIC, 3199, Australia
| | - V Plummer
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Vic, Australia
| | - F Thien
- Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Vic, Australia.,Department of Respiratory Medicine, Eastern Health, Box Hill, Vic, Australia
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King GG, Farrow CE, Chapman DG. Dismantling the pathophysiology of asthma using imaging. Eur Respir Rev 2019; 28:28/152/180111. [PMID: 30996039 DOI: 10.1183/16000617.0111-2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/01/2019] [Indexed: 11/05/2022] Open
Abstract
Asthma remains an important disease worldwide, causing high burden to patients and healthcare systems and presenting a need for better management and ultimately prevention and cure. Asthma is a very heterogeneous condition, with many different pathophysiological processes. Better measurement of those pathophysiological processes are needed to better phenotype disease, and to go beyond the current, highly limited measurements that are currently used: spirometry and symptoms. Sophisticated three-dimensional lung imaging using computed tomography and ventilation imaging (single photon emission computed tomography and positron emission tomography) and magnetic resonance imaging and methods of lung imaging applicable to asthma research are now highly developed. The body of current evidence suggests that abnormalities in structure and ventilatory function measured by imaging are clinically relevant, given their associations with disease severity, exacerbation risk and airflow obstruction. Therefore, lung imaging is ready for more widespread use in clinical trials and to become part of routine clinical assessment of asthma.
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Affiliation(s)
- Gregory G King
- Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, Australia .,Woolcock Institute of Medical Research and Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia.,Centre of Excellence in Severe Asthma, Newcastle, Australia
| | - Catherine E Farrow
- Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, Australia.,Woolcock Institute of Medical Research and Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia.,Centre of Excellence in Severe Asthma, Newcastle, Australia
| | - David G Chapman
- Woolcock Institute of Medical Research and Northern Clinical School, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia.,School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, Australia
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