129Xe MRI and Oscillometry of Irritant-Induced Asthma After Bronchial Thermoplasty.

Irritant-induced asthma (IIA) may develop after acute inhalational exposure in individuals without preexisting asthma. The effect of bronchial thermoplasty to treat intractable, worsening IIA has not yet been described. We evaluated a previously healthy 52-year-old man after inhalation of an unknown white powder. His pulmonary function and symptoms/quality of life worsened over 4 years, despite maximal guidelines-based asthma therapy. We acquired 129Xe MRI and pulmonary function test measurements on three occasions including before and after bronchial thermoplasty treatment. Seven months after bronchial thermoplasty, improved MRI ventilation and oscillometry small airway resistance were observed. Spirometry and asthma control did not improve until 19 months after bronchial thermoplasty, 5.5 years postexposure. Together, oscillometry measurements of the small airways and 129Xe MRI provided effort-independent, sensitive, and objective measurements of response to therapy. Improved MRI and oscillometry small airway resistance measurements temporally preceded improved airflow obstruction and may be considered for complex asthma cases.

Use of Quantitative CT Imaging to Identify Bronchial Thermoplasty Responders.

BACKGROUND: Bronchial thermoplasty (BT) is a treatment for patients with poorly controlled, severe asthma. However, predictors of treatment response to BT are defined poorly. RESEARCH QUESTION: Do baseline radiographic and clinical characteristics exist that predict response to BT? STUDY DESIGN AND METHODS: We conducted a longitudinal prospective cohort study of participants with severe asthma receiving BT across eight academic medical centers. Participants received three separate BT treatments and were monitored at 3-month intervals for 1 year after BT. Similar to prior studies, a positive response to BT was defined as either improvement in Asthma Control Test results of ≥ 3 or Asthma Quality of Life Questionnaire of ≥ 0.5. Regression analyses were used to evaluate the association between pretreatment clinical and quantitative CT scan measures with subsequent BT response. RESULTS: From 2006 through 2017, 88 participants received BT, with 70 participants (79.5%) identified as responders by Asthma Control Test or Asthma Quality of Life Questionnaire criteria. Responders were less likely to undergo an asthma-related ICU admission in the prior year (3% vs 25%; P = .01). On baseline quantitative CT imaging, BT responders showed less air trapping percentage (OR, 0.90; 95% CI, 0.82-0.99; P = .03), a greater Jacobian determinant (OR, 1.49; 95% CI, 1.05-2.11), greater SD of the Jacobian determinant (OR, 1.84; 95% CI, 1.04-3.26), and greater anisotropic deformation index (OR, 3.06; 95% CI, 1.06-8.86). INTERPRETATION: To our knowledge, this is the largest study to evaluate baseline quantitative CT imaging and clinical characteristics associated with BT response. Our results show that preservation of normal lung expansion, indicated by less air trapping, a greater magnitude of isotropic expansion, and greater within-lung spatial variation on quantitative CT imaging, were predictors of future BT response. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01185275; URL: www. CLINICALTRIALS: gov.

Safety and efficacy of bronchial thermoplasty in Australia 5 years post-procedure.

BACKGROUND AND OBJECTIVE: Outside clinical trials, there is limited long-term data following bronchial thermoplasty (BT). In a cohort of real-world severe asthmatics in an era of biological therapy, we sought to evaluate the safety and efficacy of BT 5 years post-treatment. METHODS: Every patient treated with BT at two Australian tertiary centres were recalled at 5 years, and evaluated by interview and record review, Asthma Control Questionnaire (ACQ), spirometry and high-resolution CT Chest. CT scans were interpreted using the modified Reiff and BRICS CT scoring systems for bronchiectasis. RESULTS: Fifty-one patients were evaluated. At baseline, this cohort had a mean age of 59.0 ± 11.8 years, mean ACQ of 3.0 ± 1.0, mean FEV1 of 55.5 ± 18.8% predicted, and 53% were receiving maintenance oral steroids in addition to triple inhaler therapy. At 5 years, there was a sustained improvement in ACQ scores to 1.8 ± 1.0 (p < 0.001). Steroid requiring exacerbation frequency was reduced from 3.8 ± 3.6 to 1.0 ± 1.6 exacerbations per annum (p < 0.001). 44% of patients had been weaned off oral steroids. No change in spirometry was observed. CT scanning identified minor degrees of localized radiological bronchiectasis in 23/47 patients with the modified Reiff score increasing from 0.6 ± 2.6 at baseline to 1.3 ± 2.5 (p < 0.001). However, no patients exhibited clinical features of bronchiectasis, such as recurrent bacterial infection. CONCLUSION: Sustained clinical benefit from BT at 5 years was demonstrated in this cohort of very severe asthmatics. Mild, localized radiological bronchiectasis was identified in a portion of patients without clinical features of bronchiectasis.

Immediate complications and flow volume changes during treatment phases of bronchial thermoplasty: a single-center descriptive study.

INTRODUCTION: Bronchial thermoplasty (B.T.) is a therapeutic bronchoscopic procedure in which controlled thermal energy is applied to the airway wall to decrease smooth muscle mass. Immediate complications of B.T. include acute exacerbation of bronchial asthma, upper and lower respiratory tract infection, hemoptysis, among others. Our study assessed these immediate adverse events and the changes in forced expiratory volume in one second (FEV1%) measured four hours after each procedure from baseline. The study also aimed to examine the number of activations during each cycle of treatment and its correlation to the corresponding change in FEV1% from baseline. METHODS: A case-series analysis of 17 patients who underwent B.T. between 2014 and 2019 was done. Demographic, clinical characteristics, including pre and post-BT FEV1% measures, and the number of activations were obtained. RESULTS: Acute exacerbation of asthma was the commonest complication accounting for 33%, 57%, and 75% after BT1, BT2, and BT3, respectively. There was deterioration in FEV1% after each treatment phase, the most significant being in BT3. There was no correlation between the number of heat activations with the change in FEV1% from baseline. CONCLUSION: The number of activations in B.T. does not correlate with the immediate deterioration in FEV1%, although exacerbation of asthma is the commonest complication post-B.T.

Safety and effectiveness of bronchial thermoplasty after 10 years in patients with persistent asthma (BT10+): a follow-up of three randomised controlled trials.

BACKGROUND: Bronchial thermoplasty is an endoscopic treatment for uncontrolled asthma. Previous randomised clinical trials have shown that bronchial thermoplasty reduces severe exacerbations in people with asthma. However, the long-term efficacy and safety of bronchial thermoplasty beyond 5 years is unknown. The BT10+ study aimed to investigate the efficacy and safety of bronchial thermoplasty after 10 or more years of follow-up. METHODS: BT10+ was an international, multicentre, follow-up study of participants who were previously enrolled in the AIR, RISA, and AIR2 trials and who had 10 or more years of follow-up since bronchial thermoplasty treatment. Data on patient demographics, quality of life, lung function, CT scans (AIR2 participants only), severe exacerbations, and health-care use during the previous year were collected at the BT10+ 10-year outcomes study visit. The primary effectiveness endpoint was durability of the thermoplasty treatment effect, determined by comparing the proportion of participants who had severe exacerbations during the first and fifth years after bronchial thermoplasty treatment with the proportion of participants who had severe exacerbations during the 12-month period before the BT10+ visit. The primary safety endpoint was the absence of clinically significant post-treatment respiratory image changes after bronchial thermoplasty, defined as bronchiectasis or bronchial stenosis as confirmed by pulmonary volumetric high-resolution CT scan at the BT10+ visit (AIR2 participants only). All analyses were done on an intention-to-treat basis. The trial is registered with ClinicalTrials.gov, NCT03243292. The last patient was enrolled on Dec 11, 2018. The last patient completed follow-up on Jan 10, 2019. FINDINGS: The BT10+ study enrolled 192 (45%) of the 429 participants who were enrolled in the AIR, RISA, and AIR2 trials. The BT10+ participants comprised 136 who received bronchial thermoplasty (52% of the 260 participants who received bronchial thermoplasty in the original trials), and 56 sham or control participants (33% of 169 from the original trials). 18 (32%) sham or control participants received bronchial thermoplasty after the previous trials concluded. The participants included in BT10+ were followed for 10·8-15·6 years (median 12·1 years) post-treatment. Baseline characteristics were similar between participants enrolled in BT10+ and those not enrolled. Participants treated with bronchial thermoplasty had similar proportions of severe exacerbations at the BT10+ visit (34 [25%] of 136 participants) compared with 1 year (33 [24%] of 135 participants; difference 0·6%, 95% CI -9·7 to 10·8) and 5 years (28 [22%] of 130 participants; difference 3·5%, -6·7% to 13·6) after treatment. Quality of life measurements and spirometry were similar between year 1, year 5, and the BT10+ visit. At the BT10+ study visit, pulmonary high-resolution CT scans from AIR2 participants treated with bronchial thermoplasty showed that 13 (13%) of 97 participants had bronchiectasis. When compared with baseline high-resolution CT scans, six (7%) of 89 participants treated with bronchial thermoplasty who did not have bronchiectasis at baseline had developed bronchiectasis after treatment (5 classified as mild, 1 classified as moderate). Participants treated with bronchial thermoplasty after the original study and participants in the sham or control group also had reductions in severe exacerbations at the BT10+ visit compared with baseline. INTERPRETATION: Our findings suggest that efficacy of bronchial thermoplasty is sustained for 10 years or more, with an acceptable safety profile. Therefore, bronchial thermoplasty is a long-acting therapeutic option for patients with asthma that remains uncontrolled despite optimised medical treatment. FUNDING: Boston Scientific.

Efficacy of bronchial thermoplasty in patients with severe asthma.

Objective: To investigate the efficacy and safety of bronchial thermoplasty (BT) in clinical practice in adults with severe, refractory asthma.Methods: Prospective, single-center, open, observational study comprising patients with uncontrolled asthma (asthma control questionnaire (ACQ) >1.5) and/or frequent exacerbations despite treatment with at least high dose inhaled corticosteroids plus a second controller. Efficacy outcomes was change from baseline 4, 8, 12 and 24 months in FEV1, FVC and FEV1/FVC ratio, asthma control questionnaire (ACQ) score and asthma quality of life score (mini-AQLQ). Results are presented as median with interquartile ranges (IQR). The following were recorded as adverse events: Un-scheduled health care contacts, rescue courses of oral corticosteroid (OCS) and/or antibiotics for exacerbation for exacerbations/respiratory tract infections (RTI).Results: Six-teen patients were enrolled (nine males, median age 50 years; 14 followed for 24 months). Compared to baseline, an improvement in FEV1, FVC, FEV1/FVC ratio, mini-AQLQ and ACQ was observed, i.e.FEV1 (IQR) 1.98 L (1.65-2.45) vs. 2.45 L (2.09-2.93) (p = 0.006), FVC (IQR) 3.23 L (2.76-4.05) vs. 3.75 L (3.22-4.36) (p = 0.041), FEV1/FVC 0.60 (IQR: 0.55-0.70) vs. 0.66 (IQR: 0.63-0.71) (p = 0.016), mini-AQLQ 4.0 (IQR: 3.2-4.9) vs. 5.6 (IQR 4.5-6.5) (p = 0.008, and ACQ 2.9 (IQR: 2.1-3.7) versus 1.5 (IQR 1.0-2.4) (p = 0.004). On the other hand, an increase was observed in unscheduled visits (p = 0.005), as well as use of OCS and antibiotics (p = 0.009 and p = 0.003, respectively).Conclusion: BT in adults with severe asthma improved ACQ, mini-AQLQ and lung function, but resulted in an increased frequency of unscheduled doctor-visits and rescue courses of OCS and antibiotics.

A case report of aspergillosis accompanied by saccular bronchodilation after bronchial thermoplasty in a 19-year-old woman.

BACKGROUND: Fungal infections are rarely reported as a complication of bronchial thermoplasty (BT) in patients without immunosuppressive comorbidity. CASE PRESENTATION: A 19-year-old woman college student was admitted to our hospital owing to uncontrolled severe asthma despite using the maximum dose of steroid inhalation. She experienced asthmatic attacks more frequently while cheerleading, which is an extracurricular activity. She received BT because she wanted to continue cheerleading. After the second BT session, she developed more sputum and cough. During the third session, white secretion and saccular bronchodilation appeared in the left lower bronchus. Aspergillus fumigatus was detected in the culture of the bronchial lavage sample, and saccular bronchodilation in the affected bronchus was observed on computed tomography (CT). Five months after the start of oral itraconazole, her subjective symptoms as well as her CT findings improved. Her asthma condition improved enough for the patient to continue cheerleading without exacerbation. CONCLUSIONS: It is necessary to consider the possibility of respiratory tract infections including fungal infections after BT. Detailed observations of the entire bronchus and sample collection for microbial culture are highly recommended.

Puzzling onsets of pneumonia sequentially after each session of bronchial thermoplasty: a case report.

BACKGROUND: Bronchial thermoplasty (BT) is a novel bronchoscopic intervention for severe persistent asthma. An increase in transient respiratory adverse events associated with BT were noted over the treatment periods, however, these events appear sporadic and should not always recur in a single individual and BT-related pneumonia has rarely been reported. CASE PRESENTATION: We present a case of uncontrolled severe asthma who developed puzzling pneumonia sequentially after each session of BT procedures. After each operation of three sequential BT procedures, she developed cough and purulent expectoration when her chest radiology showed new infiltrates right in the treatment regions. After empirical use of antibacterial agents plus physiotherapy and postural sputum drainage, her symptoms vanished and chest imaging resumed normal. CONCLUSION: The originality of our case report is related to the recurrence of pneumonia after three sequential BT procedures. To date, similar report has not been available in the literature. We hope to prompt alerts for post-BT respiratory infections, although most of them, along with other adverse events, are mild and tractable.

[Analysis of the safety and efficacy of bronchial thermoplasty for severe asthma with the first second forced expiratory volume (FEV(1)) as a percentage of the predicted value (FEV(1)%pred)<60].

Objective: To investigate the efficacy and safety of bronchial thermoplasty (BT) in severe asthma patients with the first second forced expiratory volume (FEV(1)) as a percentage of the predicted value (FEV(1)%pred) <60%. Methods: A retrospective analysis was performed on 75 patients with asthma who were treated with BT at Shenzhen University Hospital of the Chinese Academy of Sciences from January 2016 to January 2018. The patients were divided into two groups based on the FEV(1)%pred before treatment: FEV(1)%pred <60% group (39 cases) and FEV(1)%pred ≥60% group (36 cases). Comparative analysis of glucocorticoid consumption, times of acute attack, asthma control test (ACT) score, changes in lung function, and adverse reactions at 3 weeks after treatment were performed between the two groups of patients. Results: Before BT treatment, the consumption of oral prednisone, the amount of budesonide inhaled, and the times of acute attack [M (Q(1), Q(3))] in the FEV(1)%pred <60% group were significantly greater than those in the FEV(1)%pred ≥60% group, and the ACT score was significantly lower than the FEV(1)%pred ≥60% group [10.00 (0, 20.00) vs 0(0, 3.75) mg/d, 960 (320, 960) vs 320 (320, 640) µg/d, 5(4, 8) vs 4 (4, 5) times/year, 13 (9, 15) vs 17 (13, 19) scores] (all P<0.05). Except that the oral prednisone dosage in the FEV(1)%pred<60% group was still higher 1 year after treatment [0 (0, 5.00) vs 0 (0, 0) mg/d] (P=0.009), there was no significant difference in the remaining indicators between the two groups 1 year after treatment and 2 years after treatment (all P>0.05). After 1 year and 2 years of treatment, all indicators in the two groups were better than before treatment (all P<0.05). The inhaled budesonide amount and the times of acute exacerbation in the FEV(1)%pred <60% group 2 years after treatment were less than those 1 year after treatment [320 (320, 320) vs 320 (320, 640) µg/d, 0 (0, 0) vs 0(0, 1) times/year] (all P<0.05), and there was no significant difference in the remaining indicators. In the FEV(1)%pred ≥60% group, there was no significant difference between 2 years after treatment and 1 year after treatment in the above indicators except the amount of inhaled budesonide (all P>0.05). In the FEV(1)%pred <60% group, FEV(1) and the FEV(1)%pred were significantly lower than the FEV(1)%pred ≥60% group before treatment, 1 year after treatment and 2 years after treatment [FEV(1):(1.21±0.41) vs (2.26±0.80)L, (1.84±0.73) vs (2.30±0.78)L, (1.70±0.66) vs (2.38±0.76)L; FEV(1)%pred:46.2 (38.5, 53.7)% vs 80.8(66.5, 93.6)%, 60.1 (48.2, 71.6)% vs 87.4 (68.5, 96.5)%, 58.5 (48.6, 74.8)% vs 86.6 (73.0, 97.3)%] (all P<0.05). In the FEV(1)%pred <60% group, FEV(1) and FEV(1)%pred 1 year after treatment and 2 years after treatment were all increased compared with before treatment (all P<0.05). In the FEV(1)%pred ≥60% group, there was no statistical difference in FEV(1) at each time point before and after treatment (all P>0.05), but the FEV(1)%pred at 2 years after treatment was higher than before treatment (P<0.05). There were no significant differences in adverse events between the two groups (all P>0.05). Conclusion: BT can significantly improve the lung function, reduce the times of acute attack and the dosage of glucocorticoids in severe asthma patients with FEV(1)% pred<60%, which is safe and effective.

Single-Session Bronchial Thermoplasty Guided by 129Xe Magnetic Resonance Imaging. A Pilot Randomized Controlled Clinical Trial.

Rationale: Adverse events have limited the use of bronchial thermoplasty (BT) in severe asthma.Objectives: We sought to evaluate the effectiveness and safety of using 129Xe magnetic resonance imaging (129Xe MRI) to prioritize the most involved airways for guided BT.Methods: Thirty subjects with severe asthma were imaged with volumetric computed tomography and 129Xe MRI to quantitate segmental ventilation defects. Subjects were randomized to treatment of the six most involved airways in the first session (guided group) or a standard three-session BT (unguided). The primary outcome was the change in Asthma Quality of Life Questionnaire score from baseline to 12 weeks after the first BT for the guided group compared with after three treatments for the unguided group.Measurements and Main Results: There was no significant difference in quality of life after one guided compared with three unguided BTs (change in Asthma Quality of Life Questionnaire guided = 0.91 [95% confidence interval, 0.28-1.53]; unguided = 1.49 [95% confidence interval, 0.84-2.14]; P = 0.201). After one BT, the guided group had a greater reduction in the percentage of poorly and nonventilated lung from baseline when compared with unguided (-17.2%; P = 0.009). Thirty-three percent experienced asthma exacerbations after one guided BT compared with 73% after three unguided BTs (P = 0.028).Conclusions: Results of this pilot study suggest that similar short-term improvements can be achieved with one BT treatment guided by 129Xe MRI when compared with standard three-treatment-session BT with fewer periprocedure adverse events.

Bronchial thermoplasty: Redefining its role.

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.

Bronchial thermoplasty versus mepolizumab: Comparison of outcomes in a severe asthma clinic.

BACKGROUND AND OBJECTIVE: BT and interleukin-blocking monoclonal antibodies are both effective therapies for severe asthma, but there have been no direct comparisons between the two treatments. The aim of this study was to compare the efficacy and safety of BT and mepolizumab, in a real-world setting. METHODS: Patients with severe asthma despite optimized inhaler therapy were drawn from a severe asthma clinic in a tertiary hospital. Every patient commencing therapy with BT or mepolizumab was prospectively included in a national registry. At predetermined assessment points over a 12-month period, assessments were made of ACQ, spirometry, oral corticosteroid requiring exacerbations, reliever medication and maintenance oral corticosteroid use. RESULTS: A total of 91 patients with severe asthma participated: mean ACQ score 3.5 ± 1.0, FEV1 51.4 ± 17.7%, maintenance oral steroids 48.3% and 11.5 ± 10.0 inhalations/day reliever therapy. Forty-seven patients received mepolizumab and 44 received BT. Baseline characteristics were similar except significantly higher blood eosinophil count in the mepolizumab group. At 12 months, there were no differences between treatment outcomes for ACQ (1.9 ± 1.3 mepolizumab vs 1.7 ± 1.3 BT), exacerbation rate (0.9 ± 1.1 vs 0.9 ± 1.5), reduction in reliever use (-6.3 ± 10.5 vs -5.0 ± 8.8 puffs/day) or reduction in oral corticosteroids (-3.3 ± 7.5 vs - 5.8 ± 6.7 mg/day). The FEV1 improved equally (160 ± 290 vs 150 ± 460 mL). Readmission or prolonged admission was observed in 18.2% of BT patients, whilst 25.5% of mepolizumab patients had discontinued treatment at 12 months, 14.9% due to an adverse event or non-compliance. CONCLUSION: The results suggest that BT is as efficacious as mepolizumab for the treatment of severe asthma.

Bronchial Thermoplasty Including the Middle Lobe Bronchus Significantly Improves Lung Function and Quality of Life in Patients Suffering from Severe Asthma.

PURPOSE: Bronchial Thermoplasty (BT) is indicated in patients suffering from severe and symptomatic bronchial asthma despite maximal medical therapy. However, treatment of the right middle lobe (RML) bronchus is currently not recommended. The aim of this study was to investigate the safety and efficacy of BT if the RML bronchus is included. METHODS: BT was performed in 17 consecutive patients, quality of life and pulmonary function were characterized before and 90 days after BT completion. Furthermore, we performed a clean-up bronchoscopy following every BT. This study was approved by the IRB of the University of Essen (No. 17-7356 BO) and registered as a retrospective observational study at the German Clinical Trials Registry (No. DRKS 00011550). RESULTS: The median baseline values of FEV1 and Asthma Questionnaire of Life Quality (AQLQ) were 1.33 l (0.91; 1.73) and 3.01 (2.76; 3.61), respectively, and significantly improved 90 days after treatment with FEV 1 at 1.75 l (p-value 0.002) and AQLQ 3.8 (p-value < 0.05). Also the amount of oral corticosteroid necessity decreased significantly. No severe adverse events occurred due to the procedure. Clean-up bronchoscopies-when performed-revealed significant fibrinous exudation after every BT procedure. CONCLUSION: BT including the RML bronchus is feasible. Functionally limited patients with severe asthma could potentially profit. Due to the relevant fibrinous exudation, BT should be followed by clean-up bronchoscopy, not only after RML treatment.

Effect of bronchial thermoplasty on structural changes and inflammatory mediators in the airways of subjects with severe asthma.

BACKGROUND: Bronchial thermoplasty (BT) is a novel technique used in the treatment of subjects with severe refractory asthma. Radiofrequency is provided to airway walls during bronchoscopy in order to reduce airway remodeling. Several clinical studies have reported an improvement in subjects' symptoms following BT. However, how BT affects the airway architectures and inflammatory mediators in the airways has not been yet fully elucidated. METHODS: Fourteen subjects with severe asthma were recruited in this study according to the criteria of ATS severe asthma definition. The study subjects undertook bronchial biopsy during the bronchoscopy procedure at baseline and 6 weeks after the initial BT treatment. The obtained samples were stained with antibodies for α-smooth muscle actin (α-SMA); protein gene product (PGP) 9.5, a specific nerve marker; von Willebrand factor (vWF), a marker for blood vessels; interleukin-17A (IL-17A) and transforming growth factor-ß1 (TGF-ß1). RESULTS: The expression of α-SMA and PGP9.5 were significantly reduced post-BT. There was no significant difference in the number of blood vessels between baseline and post-BT. In addition, BT did not affect the production of IL-17A and TGF-ß1 in the airways. The changes in the expression of α-SMA and PGP9.5 had no significant correlation with the improvement of pulmonary function. CONCLUSION: and Clinical Relevance: This study suggests that BT reduces airway smooth muscle mass and the airway innervation without affecting vasculature and the production of inflammatory mediators in the airways of subjects with severe asthma.

A rare case of plastic bronchitis following bronchial thermoplasty

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What is the role of bronchial thermoplasty in the management of severe asthma?

Asthma is a common chronic inflammatory condition of the airways. Conventional therapy comprises inhaled corticosteroid and bronchodilators as well as trigger avoidance and management of comorbid conditions. A small group remain symptomatic despite these strategies and novel therapies have been developed. Bronchial thermoplasty is a nonpharmacological therapy which targets airway smooth muscle to improve asthma control. Clinical trials to date have shown the efficacy and safety of bronchial thermoplasty with a persistent effect on extended follow up. Questions remain regarding the exact mechanism of action of bronchial thermoplasty, the cost effectiveness of the procedure and the ideal criteria for patient selection.

In vitro, in silico and in vivo study challenges the impact of bronchial thermoplasty on acute airway smooth muscle mass loss.

Bronchial thermoplasty is a treatment for asthma. It is currently unclear whether its histopathological impact is sufficiently explained by the proportion of airway wall that is exposed to temperatures necessary to affect cell survival.Airway smooth muscle and bronchial epithelial cells were exposed to media (37-70°C) for 10 s to mimic thermoplasty. In silico we developed a mathematical model of airway heat distribution post-thermoplasty. In vivo we determined airway smooth muscle mass and epithelial integrity pre- and post-thermoplasty in 14 patients with severe asthma.In vitro airway smooth muscle and epithelial cell number decreased significantly following the addition of media heated to ≥65°C. In silico simulations showed a heterogeneous heat distribution that was amplified in larger airways, with <10% of the airway wall heated to >60°C in airways with an inner radius of ∼4 mm. In vivo at 6 weeks post-thermoplasty, there was an improvement in asthma control (measured via Asthma Control Questionnaire-6; mean difference 0.7, 95% CI 0.1-1.3; p=0.03), airway smooth muscle mass decreased (absolute median reduction 5%, interquartile range (IQR) 0-10; p=0.03) and epithelial integrity increased (14%, IQR 6-29; p=0.007). Neither of the latter two outcomes was related to improved asthma control.Integrated in vitro and in silico modelling suggest that the reduction in airway smooth muscle post-thermoplasty cannot be fully explained by acute heating, and nor did this reduction confer a greater improvement in asthma control.