Tracheobronchomalacia and excessive dynamic airway collapse

Excessive dynamic airway collapse during general anesthesia: a case report

Background

Excessive dynamic airway collapse (EDAC) is an uncommon cause of high airway pressure during mechanical ventilation. However, EDAC is not widely recognized by anesthesiologists, and therefore, it is often misdiagnosed as asthma.

Case presentation

A 70-year-old woman with a history of asthma received anesthesia with sevoflurane for a laparotomic cholecystectomy. Under general anesthesia, she developed wheezing, high inspiratory pressure, and a shark-fin waveform on capnography, which was interpreted as an asthma attack. However, treatment with a bronchodilator was ineffective. Bronchoscopy revealed the collapse of the trachea and main bronchi upon expiration. We reviewed the preoperative computed tomography scan and saw bulging of the posterior membrane into the airway lumen, leading to a diagnosis of EDAC.

Conclusions

Although both EDAC and bronchospasm present as similar symptoms, the treatments are different. Bronchoscopy proved useful for distinguishing between these two entities. Positive end-expiratory pressure should be applied and bronchodilators avoided in EDAC.

Characterization of tracheobronchomalacia in infants with hypophosphatasia

Background

Perinatal and infantile hypophosphatasia (HPP) are associated with respiratory failure and respiratory complications. Effective management of such complications is of key clinical importance. In some infants with HPP, severe tracheobronchomalacia (TBM) contributes to respiratory difficulties. The objective of this study is to characterize the clinical features, investigations and management in these patients.

Methods

We report a case series of five infants with perinatal HPP, with confirmed TBM, who were treated with asfotase alfa and observed for 3–7 years. Additionally, we reviewed respiratory function data in a subgroup of patients with perinatal and infantile HPP included in the clinical trials of asfotase alfa, who required high-pressure respiratory support (positive end-expiratory pressure [PEEP] ≥6 cm H₂O and/or peak inspiratory pressure ≥18 cm H₂O) during the studies.

Results

The case series showed that TBM contributed significantly to respiratory morbidity, and prolonged respiratory support with high PEEP was required. However, TBM improved over time, allowing weaning of all patients from ventilator use. The review of clinical trial data included 20 patients and found a high degree of heterogeneity in PEEP requirements across the cohort; median PEEP was 8 cm H₂O at any time and some patients presented with high PEEP (≥8 cm H₂O) over periods of more than 6 months.

Conclusion

In infants with HPP presenting with persistent respiratory complications, it is important to screen for TBM and initiate appropriate respiratory support and treatment with asfotase alfa at an early stage.

Trial registration

ClinicalTrials.gov numbers: NCT00744042, registered 27 August 2008; NCT01205152, registered 17 September 2010; NCT01176266, registered 29 July 2010.

Association Between Inhaled Corticosteroids and Tracheobronchomalacia

OBJECTIVE

The aim of this study was to assess any association between use of inhaled corticosteroids (ICS) and tracheobronchomalacia (TBM).

METHODS

This study was a retrospective analysis of patients with asthma and COPD, with and without TBM. Patients were diagnosed with TBM on the basis of CT imaging, flexible bronchoscopy, or both. Patients were deemed to be on ICS if they had been receiving treatment for at least 3 months. Simple logistic regression models were used to assess the association between TBM status and each proposed factor. A multivariable logistic regression model was used to assess the association between TBM and steroid dose.

RESULTS

A total of 463 patients with COPD (n = 153) and asthma (n = 310) were studied. In multivariate analysis, the odds of TBM were 3.5 times higher in patients on high-dose steroids compared with patients not on steroids (OR, 3.5; 95% CI, 1.4-8.5; P = .007). Age (P < .0001), presence of gastroesophageal reflux disease (P < .0001), use of long-acting muscarinic antagonists (P < .0001), and type of pulmonary disease (P = .002) were also associated with TBM. In patients using ICS, the odds of having TBM were 2.9 times greater in patients on high-dose inhaled steroids compared with those on low-dose inhaled steroids (OR, 2.9; 95% CI, 1.2-7.1; P = .02). Age (P = .003), presence of gastroesophageal reflux disease (P = .002), use of long-acting muscarinic antagonists (P = .004), type of ICS (P = .04), and number of months on ICS (P < .0001) were all associated with TBM.

CONCLUSIONS

There was a significant association between ICS use in higher doses for a longer duration of time with TBM. Prospective randomized controlled trials are needed to show causality of this observed association.

Combining lexical and context features for automatic ontology extension

BACKGROUND

Ontologies are widely used across biology and biomedicine for the annotation of databases. Ontology development is often a manual, time-consuming, and expensive process. Automatic or semi-automatic identification of classes that can be added to an ontology can make ontology development more efficient.

RESULTS

We developed a method that uses machine learning and word embeddings to identify words and phrases that are used to refer to an ontology class in biomedical Europe PMC full-text articles. Once labels and synonyms of a class are known, we use machine learning to identify the super-classes of a class. For this purpose, we identify lexical term variants, use word embeddings to capture context information, and rely on automated reasoning over ontologies to generate features, and we use an artificial neural network as classifier. We demonstrate the utility of our approach in identifying terms that refer to diseases in the Human Disease Ontology and to distinguish between different types of diseases.

CONCLUSIONS

Our method is capable of discovering labels that refer to a class in an ontology but are not present in an ontology, and it can identify whether a class should be a subclass of some high-level ontology classes. Our approach can therefore be used for the semi-automatic extension and quality control of ontologies. The algorithm, corpora and evaluation datasets are available at https://github.com/bio-ontology-research-group/ontology-extension.

Assessing Airflow Sensitivity to Healthy and Diseased Lung Conditions in a Computational Fluid Dynamics Model Validated In Vitro

Computational models are useful for understanding respiratory physiology. Crucial to such models are the boundary conditions specifying the flow conditions at truncated airway branches (terminal flow rates). However, most studies make assumptions about these values, which are difficult to obtain in vivo. We developed a computational fluid dynamics (CFD) model of airflows for steady expiration to investigate how terminal flows affect airflow patterns in respiratory airways. First, we measured in vitro airflow patterns in a physical airway model, using particle image velocimetry (PIV). The measured and computed airflow patterns agreed well, validating our CFD model. Next, we used the lobar flow fractions from a healthy or chronic obstructive pulmonary disease (COPD) subject as constraints to derive different terminal flow rates (i.e., three healthy and one COPD) and computed the corresponding airflow patterns in the same geometry. To assess airflow sensitivity to the boundary conditions, we used the correlation coefficient of the shape similarity (R) and the root-mean-square of the velocity magnitude difference (Drms) between two velocity contours. Airflow patterns in the central airways were similar across healthy conditions (minimum R, 0.80) despite variations in terminal flow rates but markedly different for COPD (minimum R, 0.26; maximum Drms, ten times that of healthy cases). In contrast, those in the upper airway were similar for all cases. Our findings quantify how variability in terminal and lobar flows contributes to airflow patterns in respiratory airways. They highlight the importance of using lobar flow fractions to examine physiologically relevant airflow characteristics.

ERS statement on tracheomalacia and bronchomalacia in children

Tracheomalacia and tracheobronchomalacia may be primary abnormalities of the large airways or associated with a wide variety of congenital and acquired conditions. The evidence on diagnosis, classification and management is scant. There is no universally accepted classification of severity. Clinical presentation includes early-onset stridor or fixed wheeze, recurrent infections, brassy cough and even near-death attacks, depending on the site and severity of the lesion. Diagnosis is usually made by flexible bronchoscopy in a free-breathing child but may also be shown by other dynamic imaging techniques such as low-contrast volume bronchography, computed tomography or magnetic resonance imaging. Lung function testing can provide supportive evidence but is not diagnostic. Management may be medical or surgical, depending on the nature and severity of the lesions, but the evidence base for any therapy is limited. While medical options that include bronchodilators, anti-muscarinic agents, mucolytics and antibiotics (as well as treatment of comorbidities and associated conditions) are used, there is currently little evidence for benefit. Chest physiotherapy is commonly prescribed, but the evidence base is poor. When symptoms are severe, surgical options include aortopexy or posterior tracheopexy, tracheal resection of short affected segments, internal stents and external airway splinting. If respiratory support is needed, continuous positive airway pressure is the most commonly used modality either via a face mask or tracheostomy. Parents of children with tracheobronchomalacia report diagnostic delays and anxieties about how to manage their child's condition, and want more information. There is a need for more research to establish an evidence base for malacia. This European Respiratory Society statement provides a review of the current literature to inform future study.

Translation of Quantitative Imaging Biomarkers into Clinical Chest CT

Quantitative imaging has been proposed as the next frontier in radiology as part of an effort to improve patient care through precision medicine. In 2007, the Radiological Society of North America launched the Quantitative Imaging Biomarkers Alliance (QIBA), an initiative aimed at improving the value and practicality of quantitative imaging biomarkers by reducing variability across devices, sites, patients, and time. Chest CT occupies a strategic position in this initiative because it is one of the most frequently used imaging modalities, anatomically encompassing the leading causes of mortality worldwide. To date, QIBA has worked on profiles focused on the accurate, reproducible, and meaningful use of volumetric measurements of lung lesions in chest CT. However, other quantitative methods are on the verge of translation from research grounds into clinical practice, including (a) assessment of parenchymal and airway changes in patients with chronic obstructive pulmonary disease, (b) analysis of perfusion with dual-energy CT biomarkers, and (c) opportunistic screening for coronary atherosclerosis and low bone mass by using chest CT examinations performed for other indications. The rationale for and the key facts related to the application of these quantitative imaging biomarkers in cardiothoracic chest CT are presented. ^©RSNA, 2019 See discussion on this article by Buckler (pp 977-980).

In vivo dynamics of the tracheal airway and its influences on respiratory airflows

Respiration is a dynamic process accompanied by morphological changes in the airways. Although deformation of large airways is expected to exacerbate pulmonary disease symptoms by obstructing airflow during increased minute ventilation, its quantitative effects on airflow characteristics remain unclear. Here, we used an exemplar case derived from in vivo dynamic imaging and examined the effects of tracheal deformation on airflow characteristics under different conditions. First, we measured tracheal deformation profiles of a healthy lung using magnetic resonance imaging during forced exhalation, which we simulated to characterize subject-specific airflow patterns. Subsequently, for both inhalation and exhalation, we compared the airflows when the maximal deformation in tracheal cross-sectional area was 0% (rigid), 33% (mild), 50% (moderate), or 75% (severe). We quantified differences in airflow patterns between deformable and rigid airways by computing the correlation coefficients (R) and the root-mean-square of differences (Drms) between their velocity contours. For both inhalation and exhalation, airflow patterns were similar in all branches between the rigid and mild conditions (R > 0.9; Drms < 32%). However, airflow characteristics in the moderate and severe conditions differed markedly from those in the rigid and mild conditions in all lung branches, particularly for inhalation (moderate: R > 0.1, Drms < 76%; severe: R > 0.2, Drms < 96%). Our exemplar case supports the use of a rigid airway assumption to compute flows for mild deformation. For moderate or severe deformation, however, dynamic contraction should be considered, especially during inhalation, to accurately predict airflow and elucidate the underlying pulmonary pathology.

Ultralow Dose Dynamic Expiratory Computed Tomography for Evaluation of Tracheomalacia

OBJECTIVE

The aim of this study was to determine the average effective radiation dose and feasibility of ultralow dose dynamic expiratory computed tomography (CT) for evaluation of tracheomalacia (ULD) and to evaluate factors that impact image quality.

METHODS

This is a retrospective study of 64 consecutive patients from September to October 2016 for the evaluation of tracheomalacia. All studies were performed with routine inspiration chest CT followed by ULD z(kilovoltage peak (kVp) 80, 100, or 120 and fixed milliamperage 10) or typical dose CT (TD) (kVp 100 or 120 with automated milliamperage) dynamic expiration CT. Image quality was considered diagnostic if the trachea area could be accurately measured for tracheomalacia assessment, and diagnostic studies were graded fair, good, or excellent. Scan length, image quality, and effective radiation dose were compared for ULD versus TD and ULD at 100 kVp versus ULD at 80 kVp. For ULD studies, patient factors were compared across image quality.

RESULTS

The ULD had a mean effective radiation dose of 0.08 mSv, with all studies of diagnostic image quality. The ULD showed 95% reduction in effective radiation dose (P < 0.001), 14% significant reduction in scan length (P = 0.029), and qualitatively decreased image quality compared w2 ith TD (P < 0.001). The ULD at 100 kVp had significantly better image quality compared with ULD at 80 kVp (P = 0.041) with higher effective radiation dose (0.09 vs 0.05 mSv) (P < 0.001). Body mass index significantly impacted image quality for all ULD studies but not for ULD at 80 or 100 kVp.

CONCLUSION

For evaluation of tracheomalacia, ULD showed low effective radiation dose less than 0.1 mSv and maintained diagnostic image quality.

Upper airway wheezing: Inducible laryngeal obstruction vs. excessive dynamic airway collapse

There are multiple causes of dyspnea upon exertion in young, healthy patients to primarily include asthma and exercise-induced bronchospasm. Excessive dynamic airway collapse (EDAC) describes focal collapse of the trachea or main bronchi with maintained structural integrity of the cartilaginous rings. It is commonly associated with pulmonary disorders like bronchiectasis, chronic obstructive pulmonary disease and asthma. It is believed to result secondary to airway obstruction in these conditions. While uncommon in young, healthy adults, it has recently been found as a cause of dyspnea in this population. Inducible laryngeal obstruction (ILO) is an umbrella term that describes an induced, intermittent upper airway impediment. While ILO is found in 10% of young patients with exertional dyspnea, it is primarily inspiratory in nature due to paradoxical closure of the glottis or supraglottis. This report highlights the presentation of a United States Army soldier who after a deployment was given a diagnosis of asthma, later found to have ILO and was subsequently diagnosed with concurrent EDAC. We follow up with a literature review and discussion of symptomatology, diagnosis, exercise bronchoscopy, and treatment modalities for both EDAC and ILO.

Tracheobronchomalacia and Excessive Dynamic Airway Collapse

Tracheobronchomalacia (TBM) and excessive dynamic airway collapse (EDAC) are more frequently being recognized as the etiology of multiple types of respiratory complaints from chronic cough to exertional syncope to recurrent infections. Identification of these conditions requires a high suspicion, as well as a thorough history and physical examination. Dynamic computed tomography imaging and bronchoscopic evaluation are integral in achieving an accurate diagnosis. Once recognized, treatment ranges from addressing underlying contributing conditions to surgical stabilization of the airway. Referral to an institution familiar with the evaluation and treatment of TBM/EDAC is essential for the appropriate management of these conditions.

Diagnostic flexible versus rigid bronchoscopy for the assessment of tracheomalacia in children

OBJECTIVE

This project compares the degree of tracheal collapse determined by rigid and flexible bronchoscopy in paediatric patients with tracheomalacia.

METHODS

A total of nine patients with tracheomalacia underwent both rigid and flexible video bronchoscopy. All patients were breathing spontaneously. Cross-sectional images of the airway were processed using the ImageJ program and analysed via colour histogram mode technique in order to delineate the luminal area. Paired t-tests (conducted using Stata software version 13.0) quantified differences between rigid and flexible bronchoscopes regarding the ratios of luminal pixels at maximum airway collapse to expansion. Correlation between both techniques in terms of airway collapse to expansion ratios was determined by calculating the Pearson correlation coefficient (R).

RESULTS

The difference in ratios of maximum collapse to expansion between rigid and flexible bronchoscopy was not statistically significant (p = 0.4656) and was positively correlated (R = 0.523).

CONCLUSION

The ratios suggest that rigid and flexible bronchoscopy are equally efficacious in assessing tracheomalacia severity, and may be used interchangeably in a clinical setting.

Tracheal collapsibility in adults is dynamic over time

BACKGROUND

Tracheal collapse is a weakness of the tracheal wall leading to expiratory central airway collapse of more than 50% compared to inspiration. It has previously been discussed whether the collapsibility of the greater airways is a stable or a dynamic condition. Indeed, other well-known lung diseases such as asthma are characterized by dynamic changes with respect to pulmonary function indices. There are several different morphologies of the trachea related to collapsibility such as the crescent type and the saber-sheath type both involving the tracheal cartilage and excess dynamic airway collapse only involving the posterior membranous part of the trachea. Is the morphology of the trachea important for the course of the disease? The effect or adverse effects of inhaled corticosteroids are thought to play a role in the increasing incidence of the excess tracheal collapse. In this pilot study, we hypothesized that the excess collapsibility of the tracheal wall is dynamic.

METHODS

We prospectively examined 20 patients with excessive tracheal collapse on previous CT scans performed primarily due to bronchiectasis. A repeat CT scan was performed in order to evaluate the collapsibility. Before the repeat scan, patients were trained in maximal inspiration, expiration and breathholding. CT was performed in full inspiration and at end-expiration. Image assessment was performed on a dedicated CT workstation using standard lung window display settings. The percentage expiratory collapse based on cross sectional areas from carina to the thoracic inlet was calculated. Pulmonary function tests were performed and analysed in accordance with the American Thoracic Society and the European Respiratory Society guidelines.

RESULTS

Repeat CT scan were performed after 24 month +/- 7.2. Six of the 20 participants (30%) were males. Mean age was 67 +/- 11.3 years. Mean FEV1 was 83% of predicted, FVC 96.6 % of predicted and FEV1/FVC-ratio 71%. In 45% of the patients tracheal expiratory collapse improved (by more than 10%) based on percentage change in cross sectional areas in expiration compared to inspiration. 35% of patients showed disease progression with increased collapse and in 20% the collapsibility remained unchanged.

CONCLUSION

We demonstrate that the collapsibility in a large fraction of the patients had actually improved at the follow up examination. We do not find any dependency of the change in collapsibility on the morphology of the trachea after end expiration, use of corticosteroid, or recurrent infections. In addition, no correlation between the changes in collapse and changes in the pulmonary function tests and the symptoms is observed.

Positive airway pressure devices for the management of breathlessness

PURPOSE OF REVIEW

Breathlessness is a common symptom in many chronic diseases and may be refractory to pharmacotherapy. In this review, we discuss the pathophysiology of breathlessness and the role of positive airway pressure (PAP) devices to ameliorate it.

RECENT FINDINGS

Breathlessness is directly related to neural respiratory drive, which can be modified by addressing the imbalance between respiratory muscle load and capacity. Noninvasive PAP devices have been applied to patients limited by exertional breathless and, as the disease progresses, breathlessness at rest. The application of PAP is focussed on addressing the imbalance in load and capacity, aiming to reduce neural respiratory drive and breathlessness. Indeed, noninvasive bi-level PAP devices have been employed to enhance exercise capacity by enhancing pulmonary mechanics and reduce neural drive in chronic obstructive pulmonary disease (COPD) patients, and reduce breathlessness for patients with progressive neuromuscular disease (NMD) by enhancing respiratory muscle capacity. Novel continuous PAP devices have been used to maintain central airways patency in patients with excessive dynamic airway collapse (EDAC) and target expiratory flow limitation in severe COPD.

SUMMARY

PAP devices can reduce exertional and resting breathlessness by reducing the load on the system and enhancing capacity to reduce neural respiratory drive.

Difficulty in tracheal extubation followed by tracheal collapse after balloon dilatation for tracheal stenosis therapy: A case report

RATIONALE

Tracheobronchomalacia (TBM) refers to the weakening trachea or the trachea loss of structural integrity of airway cartilaginous structures. It causes tracheal stenosis, resulting in significantly high rates of mortality. Bronchoplasty by high-pressure balloon dilation under general anesthesia is a simple but effective and safe method to treat tracheobronchial stenosis. However, recurrent postoperative dyspnea after extubation due to tracheal collapse is still a challenge for anesthetists.

PATIENT CONCERNS

A 52-year-old man weighing 72 kg was scheduled for balloon dilatation surgery under general anesthesia because of breathing difficulties caused by tracheal stenosis. His previous medical history included rheumatoid arthritis, obstructive sleep apnea syndrome (OSAS), chronic bronchitis and a history of tracheal intubation. Laryngeal computerized tomography confirmed the stenosis at the level of thyroid gland.

DIAGNOSIS

The tracheal collapse after balloon dilatation for tracheal stenosis therapy.

INTERVENTIONS

Postoperatively, the patient presented with more serious and repetitive symptoms of dyspnea after extubation when compared to that before treatment. So, we had to re-insert the laryngeal mask airway (LMA), and exclude some anesthesia-associated factors, such as laryngospasm, bronchospasm and so on. After a series of treatments, we ultimately found the cause in time (the airway collapsed), and succeeded in tracheal extubation after the stent was inserted.

OUTCOMES

The patient recovered well and reported high satisfaction with anesthesia management.

LESSONS

In such an emergency even, the anesthesiologist should take valuable treatments to ensure the patient's effective ventilation. If the anesthesia-related factors can be eliminated, tracheomalacia or airway collapse should be considered whenever dyspnea occurs in the patients who unexpectedly fail to be extubated.

A 31-year-old female with a rare cause of recurrent lower lobar collapses

Can you diagnose this patient presenting to the emergency department with a short history of productive cough and breathlessness and a history of recurrent admission for chest infections? http://ow.ly/PoHQ30kmGPi.

Tracheobronchoplasty for tracheomalacia

Tracheobronchomalacia is an uncommon acquired disorder of the central airways. Common symptoms include dyspnea, constant coughing, inability to raise secretions and recurrent respiratory infections. Evaluation includes an inspiratory-expiratory chest computed tomography (dynamic CT), an awake functional bronchoscopy and pulmonary function studies. Patients with significant associated symptoms and severe collapse on CT and bronchoscopy are offered membraneous wall plication. Tracheobronchoplasty is performed through a right thoracotomy. The posterior airway is exposed after the azygous vein is ligated. The posterior wall of the trachea (and usually both main bronchi) is plicated to a sheet of thick acellular dermis (or polypropylene mesh) with a series of 4 mattress sutures of 4-0 sutures from the thoracic inlet to the bottom of the trachea to re-shape the trachea and restore the normal D shape. Patients report generally good results with improvement of their symptoms. Quality of life is usually improved while pulmonary function tests usually are not improved.

Exertional Dyspnea and Excessive Dynamic Airway Collapse

Excessive dynamic airway collapse is a relatively new diagnosis separate from tracheobronchomalacia that is manifested by functional collapse of the large airways. Most commonly described in patients with underlying obstructive lung disease such as chronic obstructive pulmonary disease and asthma, it may contribute to increased dyspnea, cough, or exacerbations. There are few data published on the role of excessive dynamic airway collapse as related specifically to exercise. It was recently described as the cause for exertional dyspnea in individuals without underlying lung disease.

Lumen area change (Delta Lumen) between inspiratory and expiratory multidetector computed tomography as a measure of severe outcomes in asthmatic patients

BACKGROUND

Quantitative computed tomographic (QCT) biomarkers of airway morphology hold potential for understanding and monitoring regional airway remodeling in asthmatic patients.

OBJECTIVE

We sought to determine whether the change in airway lumen area between total lung capacity (TLC) and functional residual capacity (FRC) lung volumes measured from CT imaging data was correlated with severe outcomes in asthmatic patients.

METHODS

We studied 152 asthmatic patients (90 female and 62 male patients) and 33 healthy subjects (12 female and 21 male subjects) using QCT. Postprocessing of airways at generations 1 to 5 (1 = trachea) was performed for wall area percentage, wall thickness percentage (WT%), lumen area at baseline total lung capacity (LA_TLC), lumen area at baseline functional residual capacity (LA_FRC), and low attenuation area at FRC. A new metric (reflecting remodeling, distal air trapping, or both), Delta Lumen, was determined as follows: Percentage difference in lumen area (LA_TLC - LA_FRC)/LA_TLC × 100.

RESULTS

Postprocessing of 4501 airway segments was performed (3681 segments in the 152 patients with asthma and 820 segments in the 33 healthy subjects; range, 17-28 segments per subject). Delta Lumen values were negatively correlated with WT% and low attenuation area (P < .01) in asthmatic patients. Delta Lumen values were significantly lower for airway generations 3 to 5 (segmental airways) in subjects undergoing hospitalization because of exacerbation and in patients with refractory asthma requiring treatment with systemic corticosteroids. WT% and low attenuation area were positively and Delta Lumen values were negatively associated with systemic corticosteroid treatment (P < .05), suggesting that a reduced Delta Lumen value is a potential outcome biomarker in patients with severe asthma.

CONCLUSION

Reduced Delta Lumen value in the central airways measured by using QCT is a promising exploratory biomarker of unstable refractory asthma that warrants further study.

A novel endobronchial approach to massive hemoptysis complicating silicone Y-stent placement for tracheobronchomalacia: A case report

RATIONALE

Airway stabilization for severe, symptomatic tracheobronchomalacia (TBM) may be accomplished by silicone Y-stent placement. Common complications of the Y-stent include mucus plugging and granulation tissue formation.

PATIENT CONCERNS

We describe a rare case of massive hemoptysis originating from a silicone Y-stent placed for TBM.

DIAGNOSES

An emergent bronchoscopy showed an actively bleeding, pulsatile vessel at the distal end of the left bronchial limb of the Y-stent. It was felt that the bleeding was caused by, or at least impacted by, the distal left bronchial limb of the Y-stent eroding into the airway wall.

INTERVENTIONS

We hypothesized that placement of oxidized regenerated cellulose (ORC) would provide initial hemostasis, and the subsequent placement of a biocompatible surgical sealant would lead to definitive resolution.

OUTCOMES

ORC provided sufficient hemostasis and the subsequent synthetic polymer reinforced the tissue for complete cessation of the bleed.

LESSONS

The combined use of ORC and a biocompatible surgical sealant provided long-term management for life-threatening hemoptysis, and potentially morbid procedures such as embolization or surgery were avoided by advanced endobronchial therapy.

Exercise-associated Excessive Dynamic Airway Collapse in Military Personnel

RATIONALE

Evaluation of military personnel for exertional dyspnea can present a diagnostic challenge, given multiple unique factors that include wide variation in military deployment. Initial consideration is given to common disorders such as asthma, exercise-induced bronchospasm, and inducible laryngeal obstruction. Excessive dynamic airway collapse has not been reported previously as a cause of dyspnea in these individuals.

OBJECTIVES

To describe the clinical and imaging characteristics of military personnel with exertional dyspnea who were found to have excessive dynamic collapse of large airways during exercise.

METHODS

After deployment to Afghanistan or Iraq, 240 active U.S. military personnel underwent a standardized evaluation to determine the etiology of persistent dyspnea on exertion. Study procedures included full pulmonary function testing, impulse oscillometry, exhaled nitric oxide measurement, methacholine challenge testing, exercise laryngoscopy, cardiopulmonary exercise testing, and fiberoptic bronchoscopy. Imaging included high-resolution computed tomography with inspiratory and expiratory views. Selected individuals underwent further imaging with dynamic computed tomography.

MEASUREMENTS AND MAIN RESULTS

A total of five men and one woman were identified as having exercise-associated excessive dynamic airway collapse on the basis of the following criteria: (1) exertional dyspnea without resting symptoms, (2) focal expiratory wheezing during exercise, (3) functional collapse of the large airways during bronchoscopy, (4) expiratory computed tomographic imaging showing narrowing of a large airway, and (5) absence of underlying apparent pathology in small airways or pulmonary parenchyma. Identification of focal expiratory wheezing correlated with bronchoscopic and imaging findings.

CONCLUSIONS

Among 240 military personnel evaluated after presenting with postdeployment exertional dyspnea, a combination of symptoms, auscultatory findings, imaging, and visualization of the airways by bronchoscopy identified six individuals with excessive dynamic central airway collapse as the sole apparent cause of dyspnea. Exercise-associated excessive dynamic airway collapse should be considered in the differential diagnosis of exertional dyspnea.

Computational fluid dynamics evaluation of excessive dynamic airway collapse

BACKGROUND

Excessive dynamic airway collapse, which is often caused by the collapse of the posterior membrane wall during exhalation, is often misdiagnosed with other diseases; stents can provide support for the collapsing airways. The standard pulmonary function tests do not necessarily show change in functional breathing condition for evaluation of these type of diseases.

METHODS

Flow characteristics through a patient's airways with excessive dynamic airway collapse have been numerically investigated. A stent was placed to support the collapsing airway and to improve breathing conditions. Computed tomography images of the patient's pre- and post-stenting were used for generating 3-Dimensional models of the airways, and were imported into a computational fluid dynamics software for simulation of realistic air flow behavior. Unsteady simulations of the inspiratory phase and expiratory phase were performed with patient-specific boundary conditions for pre- and post-intervention cases to investigate the effect of stent placement on flow characteristic and possible improvements.

FINDINGS

Results of post-stent condition show reduced pressure, velocity magnitude and wall shear stress during expiration. The variation in wall shear stress, velocity magnitude and pressure drop is negligible during inspiration.

INTERPRETATION

Although Spirometry tests do not show significant improvements, computational fluid dynamics results show significant improvements in pre- and post-treatment results, suggesting improvement in breathing condition.

Tracheobronchopathy From Inhaled Corticosteroids

Inhaled corticosteroids (ICSs) have become the mainstay of asthma control. They are also recommended as an add-on therapy to long-acting beta agonists and anticholinergics in moderate to severe COPD with recurrent exacerbations. Ultimately this clinical practice has led to the widespread use of ICSs, which are supported by a more favorable side effect profile than that of systemic steroids.

Expiratory central airway collapse in stable COPD and during exacerbations

BACKGROUND

Tracheal obstruction resulting from expiratory tracheal deformation has been associated with respiratory symptoms and severe airway exacerbations. In chronic obstructive pulmonary disease (COPD), acute exacerbations (AECOPD) create large intrathoracic pressure swings which may increase tracheal deformation. Excessive central airway collapse (ECAC) may be diagnosed when the tracheal area on expiration is less than 50% of that on inspiration. The prevalence of ECAC in AECOPD and its temporal course have not been systematically studied.

METHODS

We prospectively recruited healthy volunteers (n = 53), stable outpatients with COPD (n = 40) and patients with hospitalised acute exacerbations of COPD (AECOPD, n = 64). 17 of the AECOPD group returned for repeat evaluation when clinically well at 6-12 weeks. All subjects underwent dynamic 320-slice computed tomography of the larynx and trachea during tidal breathing, enabling quantitation of tracheal area and dimensions (mean ± SD).

RESULTS

No healthy individuals had ECAC. The prevalence of ECAC in stable COPD and AECOPD was 35% and 39% respectively. Mean tracheal collapse did not differ between stable COPD (57.5 ± 19.8%), AECOPD (53.8 ± 19.3%) and in the subset who returned when convalescent (54.9 ± 17.2%). AECOPD patients with and without ECAC had similar clinical characteristics.

CONCLUSIONS

Tracheal collapse in both stable and AECOPD is considerably more prevalent than in healthy individuals. ECAC warrants assessment as part of comprehensive COPD evaluation and management. Further studies should evaluate the aetiology of ECAC and whether it predisposes to exacerbations.

Our Experience on Silicone Y-Stent for Severe COPD Complicated With Expiratory Central Airway Collapse

BACKGROUND

Expiratory central airway collapse (ECAC) is abnormal central airway narrowing during expiration. ECAC involves 2 different pathophysiological entities as tracheobronchomalacia and excessive dynamic airway collapse (EDAC). Although the exact cause is unknown, chronic obstructive pulmonary disease (COPD) is frequently accompanied by ECAC. Although there are various publications on the relationship between COPD and ECAC, there are very few data for stent placement in patients with tracheobronchomalacia accompanied severe COPD. We share our results for stenting in ECAC among patients with severe COPD.

METHODS

The data in this case series were collected retrospectively. The ECAC diagnosis was made during flexible bronchoscopy with severe COPD. Silicone Y-stents were placed via rigid bronchoscopy under general anesthesia.

RESULTS

A total of 9 patients' (7 men) data were evaluated with an average age of 67±10.73 years. One patient experienced stent migration on the second day of stenting prompting stent removal. Another patient died 1 month after stenting. Consequently, we evaluated the follow-up data of remaining 7 patients. The changes in forced expiratory volume 1 was not significant for these 7 cases (P=0.51). The modified Medical Research Council (mMRC) score improvement was statistically significant (P=0.03). Functional status improvement was observed in 4 of 7 patients. Of the 7 patients, mean additional follow-up bronchoscopic interventions requirement was 2.2 times.

CONCLUSIONS

Our study showed significant decrease in mMRC score with stenting for ECAC in severe COPD. For 2 patients, we experienced severe complications during short-term follow-up period after stenting. Additional follow-up bronchoscopic interventions were required.

Tracheobronchomalacia

The term tracheobronchomalacia refers to excessively compliant and collapsible central airways leading to symptoms. Although seen as a coexisting condition with various other pulmonary condition, it may cause symptoms by itself. The condition is often misdiagnosed as asthma, bronchitis or just chronic cough due to a lack of specific pathognomonic history and clinical findings. The investigation revolves around different modes of imaging, lung function testing and usually confirmed by flexible bronchoscopy. The treatment widely varies based on the cause, with most cases treated conservatively with non-invasive ventilation. Some may require surgery or stent placement. In this article, we aim to discuss the pathophysiology behind this condition and recognize the common symptoms and causes of tracheobronchomalacia. The article will highlight the diagnostic steps as well as therapeutic interventions based on the specific cause.

Phenotypic presentation of chronic cough in children

Chronic cough in children is increasingly defined as a cough that lasts more than four weeks. It is recognized as a different entity than cough in adults. As a result, the diagnostic approach and management of chronic cough in children are no longer extrapolated from adult guidelines. These differences are attributed to the various characteristics of the respiratory tract, immunological system and nervous system in children. Specific paediatric guidelines and algorithms for chronic cough are now widely applied. Post-infectious cough, asthma, bronchiectasis, malacia and protracted bacterial bronchitis (PBB) appear to be the major causes of cough in young children. By adolescence, the causes of cough are more likely to be similar to those in adults, namely, gastroesophageal reflux, asthma, and upper airway syndrome. In a primary setting, it is essential to investigate the underlying disease entity that initiates and sustains chronic cough. The use of cough management protocols or algorithms improves clinical outcomes and should differ depending on the associated characteristics of the cough and the child's clinical history. Performing a thorough history and physical examination is crucial to starting an individualised approach. A correct interpretation of the phenotypic presentation can be translated into guidance for workup. This approach will be helpful for adequate management without the risk of inappropriate investigations or inadequate treatment.

Airway compliance measured by anatomic optical coherence tomography

Quantification of airway compliance can aid in the diagnosis and treatment of obstructive airway disorders by detecting regions vulnerable to collapse. Here we evaluate the ability of a swept-source anatomic optical coherence tomography (SSaOCT) system to quantify airway cross-sectional compliance (CC) by measuring changes in the luminal cross-sectional area (CSA) under physiologically relevant pressures of 10-40 cmH₂O. The accuracy and precision of CC measurements are determined using simulations of non-uniform rotation distortion (NURD) endemic to endoscopic scanning, and experiments performed in a simplified tube phantom and ex vivo porcine tracheas. NURD simulations show that CC measurements are typically more accurate than that of the CSAs from which they are derived. Phantom measurements of CSA versus pressure exhibit high linearity (R²>0.99), validating the dynamic range of the SSaOCT system. Tracheas also exhibited high linearity (R² = 0.98) suggestive of linear elasticity, while CC measurements were obtained with typically ± 12% standard error.

Awareness, Competencies, and Practice Patterns in Tracheobronchomalacia: A Survey of Pulmonologists

BACKGROUND

Tracheobronchomalacia (TBM) is a disorder of expiratory central airway collapse. TBM is separate from excessive dynamic airway collapse. Historically TBM has lacked a universally accepted definition. No consensus recommendations on evaluation and management exist. We suspect these unresolved issues contribute to deficits in pulmonologists' awareness and management of TBM.

METHODS

We created a 20-question survey obtaining information about overall awareness, knowledge base, competencies, and practice patterns in managing TBM. The survey was disseminated via email by American College of Chest Physicians to members of their Interventional Chest Diagnostic Procedures Network.

RESULTS

One hundred sixty-five clinicians participated in the survey. Seventy-seven percent of respondents chose the correct definition for TBM. Twenty-two percent of respondents never considered TBM in patients with cough, sputum production, dyspnea, and recurrent infections. Thirty-eight percent did not proceed with further evaluation of TBM if pulmonary function tests were normal. Eighteen percent use a classification system to describe the severity of TBM. Only 29% could identify TBM on bronchoscopy and only 39% identified TBM on computed tomography. Respondents that practice interventional pulmonology demonstrated a better knowledge base of TBM.

CONCLUSION

This survey exposes deficits among pulmonologists in their ability to confidently and correctly diagnose and manage TBM. These deficits are not surprising as our understanding of this clinical entity is evolving. There exists a need for further education of pulmonologists about TBM and a need to promote collaborative efforts through research and expert consensus committees to progress our knowledge and management of this disease.

Current concepts in severe adult tracheobronchomalacia: evaluation and treatment

There is increasing recognition of tracheobronchomalacia (TBM) in patients with respiratory complaints, though its true incidence in the adult population remains unknown. Most of these patients have an acquired form of severe diffuse TBM of unclear etiology. The mainstays of diagnosis are dynamic (inspiratory and expiratory) airway computed tomography (CT) scan and dynamic flexible bronchoscopy with forced expiratory maneuvers. While the prevailing definition of TBM is 50% reduction in cross-sectional area, a high proportion of healthy volunteers meet this threshold, thus this threshold fails to identify patients that might benefit from intervention. Therefore, we consider complete or near-complete collapse (>90% reduction in cross-sectional area) of the airway to be severe enough to warrant potential intervention. Surgical central airway stabilization by posterior mesh splinting (tracheobronchoplasty) effectively corrects malacic airways and has been shown to lead to significant improvement in symptoms, health-related quality of life, as well as functional and exercise capacity in carefully selected adults with severe diffuse TBM. A short-term stent trial clarifies a patient's candidacy for surgical intervention. Coordination of care between experienced interventional pulmonologists, radiologists, and thoracic surgeons is essential for optimal outcomes.

Tracheobronchomalacia as a Rare Cause of Chronic Dyspnea in Adults

OBJECTIVE

To emphasize the importance of a careful clinical evaluation to prevent unnecessary interventions and treatments.

CLINICAL PRESENTATION AND INTERVENTION

A 76-year-old female patient had been diagnosed with asthma during previous admissions to different hospitals. She had also undergone fiberoptic bronchoscopy (FOB) on 2 occasions for evaluation of right middle lobe atelectasis observed on computed tomography. A repeated FOB revealed tracheobronchomalacia and nodular bronchial amyloidosis. A silicone Y stent was inserted, but the dyspnea increased. Excessive granulation tissue developed, and the patient died despite ventilatory support.

CONCLUSION

The stenting technique used did not prevent the development of respiratory failure and death in this patient. Hence, a surgical procedure could be considered as an alternative to stenting in such cases.

Mounier-Kuhn syndrome: a case of tracheal smooth muscle remodeling

Mounier–Kuhn syndrome is a rare clinical disorder characterized by tracheobronchial dilation and recurrent lower respiratory tract infections. While the etiology of the disease remains unknown, histopathological analysis of Mounier–Kuhn airways demonstrates that the disease is, in part, characterized by cellular changes in airway smooth muscle.

Segmental bronchi collapsibility: computed tomography-based quantification in patients with chronic obstructive pulmonary disease and correlation with emphysema phenotype, corresponding lung volume changes and clinical parameters

BACKGROUND

Global pulmonary function tests lack region specific differentiation that might influence therapy in severe chronic obstructive pulmonary disease (COPD) patients. Therefore, the aim of this work was to assess the degree of expiratory 3^rd generation bronchial lumen collapsibility in patients with severe COPD using chest-computed tomography (CT), to evaluate emphysema-phenotype, lobar volumes and correlate results with pulmonary function tests.

METHODS

Thin-slice chest-CTs acquired at end-inspiration & end-expiration in 42 COPD GOLD IV patients (19 females, median-age: 65.9 y) from November 2011 to July 2014 were re-evaluated. The cross-sectional area of all segmental bronchi was measured 5 mm below the bronchial origin in both examinations. Lung lobes were semi-automatically segmented, volumes calculated at end-inspiratory and end-expiratory phase and visually defined emphysema-phenotypes defined. Results of CT densitometry were compared with lung functional tests including forced expiratory volume at 1 s (FEV₁), total lung capacity (TLC), vital capacity (VC), residual volume (RV), diffusion capacity parameters and the maximal expiratory flow rates (MEFs).

RESULTS

Mean expiratory bronchial collapse was 31%, stronger in lobes with homogenous (38.5%) vs. heterogeneous emphysema-phenotype (27.8%, P=0.014). The mean lobar expiratory volume reduction was comparable in both emphysema-phenotypes (volume reduction 18.6%±8.3% in homogenous vs. 17.6%±16.5% in heterogeneous phenotype). The degree of bronchial lumen collapsibility, did not correlate with expiratory volume reduction. MEF₂₅ correlated weakly with 3^rd generation airway collapsibility (r=0.339, P=0.03). All patients showed a concentric expiratory reduction of bronchial cross-sectional area.

CONCLUSIONS

Changes in collapsibility of 3^rd generation bronchi in COPD grade IV patients is significantly lower than that in the trachea and the main bronchi. Collapsibility did not correlate with the reduction in lung volume but was significantly higher in lobes with homogeneous vs. heterogeneous emphysema phenotype. Changes in the 3^rd generation bronchial calibres between inspiration and expiration are not predictive for the degree of small airway collapsibility and related airflow limitation.

Tracheobronchomalacia diagnosed by tracheobronchography in ventilator-dependent infants

BACKGROUND

Tracheobronchomalacia prevalence in premature infants on prolonged mechanical ventilation is high.

OBJECTIVE

To examine the prevalence of tracheobronchomalacia diagnosed by tracheobronchography in ventilator-dependent infants, and describe the demographic, clinical and dynamic airway characteristics of those infants with tracheobronchomalacia.

MATERIALS AND METHODS

This retrospective review studies 198 tracheobronchograms performed from 1998 to 2011 in a cohort of 158 ventilator-dependent infants <2 years of age. Dynamic airway assessment during tracheobronchography determined the optimal positive end-expiratory pressure to maintain airway patency at expiration in those infants with tracheobronchomalacia.

RESULTS

Tracheobronchograms were performed at a median age of 52 weeks post menstrual age. The primary diagnoses in these infants were bronchopulmonary dysplasia (53%), other causes of chronic lung disease of infancy (28%) and upper airway anomaly (13%). Of those with bronchopulmonary dysplasia, 48% had tracheobronchomalacia. Prematurity (P=0.01) and higher baseline - pre-tracheobronchogram positive end-expiratory pressure (P=0.04) were significantly associated with tracheobronchomalacia. Dynamic airway collapse during tracheobronchography showed statistically significant airway opening at optimal positive end-expiratory pressure (P < 0.001). There were no significant complications noted during and immediately following tracheobronchography.

CONCLUSION

The overall prevalence of tracheobronchomalacia in this cohort of ventilator-dependent infants is 40% and in those with bronchopulmonary dysplasia is 48%. Infants born prematurely and requiring high pre-tracheobronchogram positive end-expiratory pressure were likely to have tracheobronchomalacia. Tracheobronchography can be used to safely assess the dynamic function of the airway and can provide the clinician the optimal positive end-expiratory pressure to maintain airway patency.

Tracheal suspension by using 3-dimensional printed personalized scaffold in a patient with tracheomalacia

The major methods are used to fix or stabilize the central airways and major bronchi with either anterior suspension and/or posterior fixation for severe tracheomalacia (TM). Many support biomaterials, like mesh and sternal plate, can be used in the surgery. But there are no specialized biomaterials for TM which must be casually fabricated by the doctors in operation. Three dimensional printing (3DP) has currently untapped potential to provide custom, protean devices for challenging and life-threatening disease processes. After meticulous design, we created a polycaprolactone (PCL) scaffold for a female patient with TM, which would support for at least 24 months, to maintain the native lumen size of collapsed airways. Using 4-0 Polyglactin sutures, we grasped and suspended the malacic trachea into the scaffold. A remarkable improvement can be observed in the view of bronchoscope and chest CT after surgery. In the narrowest cavity of malacic trachea, the inner diameter increased from 0.3 to 1.0 cm, and the cross sectional area increased 4-5 times. The patient felt an obvious relief of dyspnea after surgery. In a word, the 3DP PCL scaffold can supply a personalized tool for suspending the malacic trachea in the future.

[CPAP interest in help of mucus clearance in tracheo-bronchomalacia outpatients]

The patients suffering of trachea bronchial dyskinesia in a context of trachea bronchomalacia present an important decrease of the expiratory flow during the Forced Expiration Techniques, and during the cough, returning difficult mucus clearance. The use of CPAP for these patients as a pneumatic prothesis can bring a considerable help during the chest physiotherapy techniques, avoiding the tracheobronchial collapse. The objectivation of the efficiency of this technique through a clinical case, its ease of application and control, allows us to propose the attempt of this additive help when the indication and the contraindications are clearly defined.

Tracheobronchomalacia/excessive dynamic airway collapse in patients with chronic obstructive pulmonary disease with persistent expiratory wheeze: A pilot study

BACKGROUND

Tracheobronchomalacia (TBM) refers to a condition in which structural integrity of cartilaginous wall of trachea is lost. Excessive dynamic airway collapse (EDAC) is characterized by excessive invagination of posterior wall of trachea. In both these conditions, airway lumen gets compromised, especially during expiration, which can lead to symptoms such as breathlessness, cough, and wheezing. Both these conditions can be present in obstructive lung diseases; TBM due to chronic airway inflammation and EDAC due to dynamic compressive forces during expiration. The present study was planned with the hypothesis that TBM/EDAC could also produce expiratory wheeze in patients with obstructive airway disorders. Hence, prevalence and factors affecting presence of this entity in patients with obstructive airway diseases were the aims and objectives of this study.

MATERIALS AND METHODS

Twenty-five patients with obstructive airway disorders (chronic obstructive pulmonary disease [COPD] or bronchial asthma), who were stable on medical management, but having persistent expiratory wheezing, were included in the study. They were evaluated for TBM/EDAC by bronchoscopy and computed tomographic scan of chest. The presence of TBM/EDAC was correlated with variables including age, sex, body mass index (BMI), smoking index, level of dyspnea, and severity of disease.

RESULTS

Mean age of the patients was 62.7 ± 7.81 years. Out of 25 patients, 14 were males. TBM/EDAC was found in 40% of study subjects. Age, sex, BMI, severity of disease, frequency of exacerbations and radiological findings etc., were not found to have any association with presence of TBM/EDAC.

CONCLUSION

TBM/EDAC is common in patients with obstructive airway disorders and should be evaluated in these patients, especially with persistent expiratory wheezing as diagnosis of this entity could provide another treatment option in these patients with persistent symptoms despite medical management.

Surgical Treatment of Tracheobronchomalacia: A novel approach

Tracheobronchomalacia, as a whole, is likely misdiagnosed and underestimated as a cause of respiratory compromise in pediatric patients. Currently, there is no standardized approach for the overall evaluation of pediatric tracheobronchomalacia (TBM) and the concept of excessive dynamic airway collapse (EDAC); no grading score for the evaluation of severity; nor a standardized means to successfully approach TBM and EDAC. This paper describes our experience standardizing the approach to these complex patients whose backgrounds include different disease etiologies, as well as a variety of comorbid conditions. Preoperative and postoperative evaluation of patients with severe TBM and EDAC, as well as concurrent development of a prospective grading scale, has allowed us to ascertain correlation between surgery, symptoms, and effectiveness on particular tracheal-bronchial segments. Long-term, continued collection of patient characteristics, surgical technique, complications, and outcomes must be collected given the overall heterogeneity of this particular population.