Tracheobronchomalacia and excessive dynamic airway collapse

Twin airway abnormalities complicating the management of acute asthma: a case report

The term ‘refractory asthma’ includes patients with severe asthma, steroid-dependent and/or resistant asthma, difficult-to-treat asthma and irreversible asthma. In patients with to difficult to treat asthma, exclusion of other causes of persistent wheeze like vocal cord dysfunction, upper airway obstruction and allergic bronchopulmonary aspergillosis is important. Besides, the presence of anatomical abnormalities that could affect effective medication delivery could also result in sub-optimal treatment response. These factors reiterate the need for a rigorous and systematic approach to rule out alternative co-existent diseases or abnormalities in a patient with difficult-to-treat asthma. We hereby report a case of an asthmatic patient with refractory bronchospasm despite optimal treatment, wherein work-up for an additional pathophysiological process aided in successful management of his symptoms.

Excessive dynamic airway collapse in a small cohort of chronic obstructive pulmonary disease patients

INTRODUCTION

The prevalence of EDAC (Excessive Dynamic Airway Collapse) has not been studied specifically in patients with chronic obstructive pulmonary disease (COPD).

OBJECTIVE

The aim of this study was to investigate the prevalence of EDAC in COPD and to determine whether there are clinical factors or functional variables that could influence the degree of expiratory collapse of central airways.

METHODS

Prospective observational study of a group of patients with COPD. The degree of tracheobronchial collapse was evaluated by low-dose dynamic airway computed tomography (CT). We recorded clinical and pulmonary function tests data, quality of life and BODE index.

RESULTS

This study included 53 patients with COPD, 46 (87%) males, mean age 65 (SD, 9) years.

CONCLUSIONS

The prevalence of EDAC observed in a sample of patients with different levels of COPD severity is low. The degree of dynamic central airway collapse was not related to the patient's epidemiological or clinical features, and did not affect lung function, symptoms, capacity for effort, or quality of life.

Tracheobronchomalacia in pediatric patients with esophageal atresia: comparison of diagnostic laryngoscopy/bronchoscopy and dynamic airway multidetector computed tomography

PURPOSE

Diagnostic laryngoscopy and bronchoscopy (DLB) has been the traditional preoperative diagnostic modality for evaluating presence and severity of tracheobronchomalacia (TBM), and requires anesthesia. Alternatively, multidetector computed tomography (MDCT) is potentially a noninvasive modality that provides high-resolution, 3-dimensional (3D) imaging of the thorax providing preoperative guidance for pediatric surgeons. This study compares MDCT with intraoperative DLB in the assessment of TBM in symptomatic pediatric patients with esophageal atresia (EA).

METHODS

Following IRB approval all pediatric patients (≤18 years) who had EA and who underwent an MDCT study as a preoperative evaluation of TBM prior to aortopexy were retrospectively reviewed. Patients with incomplete reports on intraoperative DLB or MDCT studies were excluded. Two pediatric radiologists independently evaluated all MDCT studies in a blinded fashion. On both DLB and MDCT studies, TBM was scored as present or absent in five anatomic segments: upper, middle, and lower trachea, as well as right and left main stem bronchi. Operative reports including DLB findings were reviewed and compared to findings from MDCT study using the chance corrected kappa (κ) coefficient. Diagnostic accuracy of dynamic MDCT for detecting TBM was determined by sensitivity and specificity, and interobserver agreement between two radiology reviewers was measured by the kappa statistic.

RESULTS

The final study population included 18 patients (8 males and 10 females) with ages ranging from 1month to 11years (median: 7 months). Their presenting clinical symptoms included apneic spells (n=15, 83%) and failure to extubate (n=3, 17%). The overall diagnostic accuracy of dynamic airway MDCT compared to DLB was 91% (82/90 possible segments for TBM) with excellent overall agreement across all 5 anatomic segments (κ=0.82, p<0.001). The agreements for upper, mid, lower trachea, and right and left trachea were 89% (κ=0.73, p<0.001), 94% (κ=0.85, p<0.001), 89% (κ=0.76, p<0.001), 94% (κ=0.82, p<0.001), and 89% (κ=0.61, p=0.005); respectively. Interobserver agreement between two radiologists was excellent (κ=0.98, 95% confidence interval: 0.94-1.00, p<0.001) with only 1 disagreement between two radiologists that was found for the left main bronchus. Fifteen (83.3%) of the patients clinically improved after the aortopexy.

CONCLUSION

MDCT with 3D imaging is a highly accurate and reliable preoperative noninvasive imaging modality for evaluating TBM in pediatric patients with EA providing anatomic information consistent with and complimentary to bronchoscopy.

Potential role of the airway wall in the asthma of obesity

The pathogenesis of late-onset TH2-low asthma in obesity is thought to be related to weight-related decreases in lung volume, but why only a subset of individuals with obesity develop this condition is unknown. We tested the hypothesis that natural variations in both airway wall stiffness and airway wall thickness could lead to a subpopulation of hyperresponsive individuals exhibiting the symptoms of asthma in the setting of obesity. Increases in airway resistance (Raw) after airway smooth muscle stimulation were simulated using a computational model of an elastic airway embedded in elastic parenchyma. Using a range of randomly chosen values for both airway wall stiffness and thickness, we determined the resulting probability distributions of Raw responsiveness for a variety of different levels of transpulmonary pressure (Ptp). As Ptp decreased from 5 to 1 cmH2O, the resulting distributions of Raw moved toward progressively higher levels of responsiveness. With appropriate choices for the mean and standard deviation of the parameter that controls either airway wall stiffness or thickness, the model predicts a relationship between airway hyperresponsiveness and body mass index that is similar to that which has been reported in populations with obesity. We conclude that natural variations in airway wall mechanics and geometry between different individuals can potentially explain why an increasing percentage of the population exhibits the symptoms of asthma as the obesity of the population increases.

A surprising cause of wheezing in a morbidly obese patient: a case report

A typical patient with chronic obstructive pulmonary disease has small airway disease, which often responds to bronchodilators. If the patient is obese, he or she may be further compromised and not tolerate being in the supine position. We present a case of a patient with history of chronic obstructive pulmonary disease and obstructive sleep apnea with acute renal failure and urosepsis scheduled for an emergent debridement of Fournier's gangrene. In this patient, the fiberoptic intubation was performed in semi-Fowler's position, and tracheomalacia was observed.

Effect of Mucin and Bicarbonate Ion on Corrosion Behavior of AZ31 Magnesium Alloy for Airway Stents

The biodegradable ability of magnesium alloys is an attractive feature for tracheal stents since they can be absorbed by the body through gradual degradation after healing of the airway structure, which can reduce the risk of inflammation caused by long-term implantation and prevent the repetitive surgery for removal of existing stent. In this study, the effects of bicarbonate ion (HCO₃⁻) and mucin in Gamble’s solution on the corrosion behavior of AZ31 magnesium alloy were investigated, using immersion and electrochemical tests to systematically identify the biodegradation kinetics of magnesium alloy under in vitro environment, mimicking the epithelial mucus surfaces in a trachea for development of biodegradable airway stents. Analysis of corrosion products after immersion test was performed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) was used to identify the effects of bicarbonate ions and mucin on the corrosion behavior of AZ31 magnesium alloys with the temporal change of corrosion resistance. The results show that the increase of the bicarbonate ions in Gamble’s solution accelerates the dissolution of AZ31 magnesium alloy, while the addition of mucin retards the corrosion. The experimental data in this work is intended to be used as foundational knowledge to predict the corrosion behavior of AZ31 magnesium alloy in the airway environment while providing degradation information for future in vivo studies.

Non-malignant central airway obstruction

The most common causes of non-malignant central airway obstruction are post-intubation and post-tracheostomytracheal stenosis, followed by the presence of foreign bodies, benign endobronchial tumours and tracheobronchomalacia. Other causes, such as infectious processes or systemic diseases, are less frequent. Despite the existence of numerous classification systems, a consensus has not been reached on the use of any one of them in particular. A better understanding of the pathophysiology of this entity has allowed us to improve diagnosis and treatment. For the correct diagnosis of nonspecific clinical symptoms, pulmonary function tests, radiological studies and, more importantly, bronchoscopy must be performed. Treatment must be multidisciplinary and tailored to each patient, and will require surgery or endoscopic intervention using thermoablative and mechanical techniques.

The use of self-expandable metallic stents in the airways in the adult population

The airway stents restore patency in the face of luminal compromise from intrinsic and/or extrinsic pathologies. Luminal compromise beyond 50% often leads to debilitating symptoms such as dyspnea. Silicone stents remain the most commonly placed stents worldwide and have been the "gold standard" for the treatment of benign and malignant airway stenoses over the past 20 years. Nevertheless, silicone stents are not the ideal stents in all situations. Metallic stents can serve better in some selected conditions. Unlike silicone stents, there are large and increasing varieties of metallic stents available on the market. The lack of prospective or comparative studies between various types of metallic stents makes the choice difficult and expert-opinion based. International guidelines are sorely lacking in this area.

The relationships between tracheal index and lung volume parameters in mild-to-moderate COPD

BACKGROUND

Although elongated morphological changes in the trachea are known to be related to lung function in chronic obstructive pulmonary disease (COPD), whether the tracheal morphological changes are associated with airflow limitations or overinflation of the lung in the early stages of COPD has not yet been determined. Thus, our aim was to investigate the association of tracheal index (TI) with lung function parameters, including lung volume parameters, in COPD patients with mild-to-moderate airflow limitations.

MATERIALS AND METHODS

A retrospective study was conducted in 193 COPD patients with GOLD grades 1-2 (post-bronchodilator forced expiratory volume in 1s [FEV1] ≥ 50% predicted with FEV1/forced vital capacity ratio ≤ 70%; age range, 40-81) and 193 age- and gender-matched subjects with normal lung function as a control group (age range, 40-82). Two independent observers measured TI at three anatomical levels on chest radiographs and CT scans.

RESULTS

Compared with the control group, TI was reduced significantly and "saber-sheath trachea" was observed more frequently in COPD patients. Patients with GOLD grade 2 disease had a lower TI than those with GOLD grade 1. TI had apparent inverse correlations with total lung capacity, functional residual capacity, and residual volume, regardless of the anatomical level of the trachea. Even after adjustments for covariates, this association persisted.

CONCLUSIONS

TI is reduced even in mild-to-moderate COPD patients, and TI measured on chest CT shows significant inverse relationships with all lung volume parameters assessed, suggesting that tracheal morphology may change during the early stages of COPD.

Refractory asthma treatment is complicated by tracheobronchomalacia: case reports and review of the literature

Tracheobronchomalacia (TBM) is defined as the condition where the airway lumen narrows more than 50 percent. The acquired TBM usually occurs in adults; however, the prevalence of TBM in asthma is unknown. We report two cases of severe asthma in elderly patients that could not be controlled with higher medication use. Case 1 was a 70-year-old woman with sever persistent asthma for 10 years, presented with uncontrolled symptoms for 4 months. A CT of the chest showed collapse of the trachea at the posterior wall. Case 2 involved a 72-year-old woman with partly controlled asthma presenting with uncontrolled symptoms for 3 months. A CT of the chest showed normal distal tracheal anteroposterior diameter. However, bronchoscopy showed bronchomalacia at the right and left bronchus of the lower lungs. Patients who have severe asthma, despite adequate treatment with medication, should be further investigated to exclude other diseases that have clinical features similar to asthma such as tracheobronchomalacia, particularly in the elderly.

Dynamic expiratory tracheal collapse in COPD: correlation with clinical and physiologic parameters

BACKGROUND

COPD has been described as a risk factor for excessive expiratory tracheal collapse, but its prevalence and clinical correlates have not been fully determined. The purpose of this study is to prospectively determine the prevalence of excessive expiratory tracheal collapse among patients with COPD and to test the hypothesis that clinical and/or physiologic parameters will correlate with the presence of excessive tracheal collapse.

METHODS

We studied 100 adults meeting GOLD (Global Initiative for Obstructive Lung Disease) criteria for COPD, who underwent full pulmonary function tests (PFTs), 6-min walk test (6MWT), St. George's Respiratory Questionnaire (SGRQ), and low-dose CT scan at total lung capacity and during dynamic exhalation with spirometric monitoring. We examined correlations between percentage dynamic expiratory tracheal collapse and PFTs, 6MWT distance, and SGRQ scores.

RESULTS

Patients included 48 women and 52 men with mean age 65 ± 7 years, FEV₁ 64% ± 22% predicted, and percentage expiratory collapse 59% ± 19%. Twenty of 100 participants met study criteria for excessive expiratory collapse. There was no significant correlation between percentage expiratory tracheal collapse and any pulmonary function measure, total SGRQ score, or 6MWT distance. The SGRQ symptom subscale was weakly correlated with percentage collapse of the mid trachea (R = 0.215, P = .03).

CONCLUSIONS

Excessive expiratory tracheal collapse is observed in a subset of patients with COPD, but the magnitude of collapse is independent of disease severity and does not correlate significantly with physiologic parameters. Thus, the incidental identification of excessive expiratory tracheal collapse in a general COPD population may not necessarily be clinically significant.

Multidetector CT and postprocessing in planning and assisting in minimally invasive bronchoscopic airway interventions

A widening spectrum of increasingly advanced bronchoscopic techniques is available for the diagnosis and treatment of various bronchopulmonary diseases. The evolution of computed tomography (CT)-multidetector CT in particular-has paralleled these advances. The resulting development of two-dimensional and three-dimensional (3D) postprocessing techniques has complemented axial CT interpretation in providing more anatomically familiar information to the pulmonologist. Two-dimensional techniques such as multiplanar recontructions and 3D techniques such as virtual bronchoscopy can provide accurate guidance for increasing yield in transbronchial needle aspiration and transbronchial biopsy of mediastinal and hilar lymph nodes. Sampling of lesions located deeper within the lung periphery via bronchoscopic pathways determined at virtual bronchoscopy are also increasingly feasible. CT fluoroscopy for real-time image-guided sampling is now widely available; electromagnetic navigation guidance is being used in select centers but is currently more costly. Minimally invasive bronchoscopic techniques for restoring airway patency in obstruction caused by both benign and malignant conditions include mechanical strategies such as airway stent insertion and ablative techniques such as electrocauterization and cryotherapy. Multidetector CT postprocessing techniques provide valuable information for planning and surveillance of these treatment methods. In particular, they optimize the evaluation of dynamic obstructive conditions such as tracheobronchomalacia, especially with the greater craniocaudal coverage now provided by wide-area detectors. Multidetector CT also provides planning information for bronchoscopic treatment of bronchopleural fistulas and bronchoscopic lung volume reduction for carefully selected patients with refractory emphysema.

Respiratory and sleep disorders in mucopolysaccharidosis

MPS encompasses a group of rare lysosomal storage disorders that are associated with the accumulation of glycosaminoglycans (GAG) in organs and tissues. This accumulation can lead to the progressive development of a variety of clinical manifestations. Ear, nose, throat (ENT) and respiratory problems are very common in patients with MPS and are often among the first symptoms to appear. Typical features of MPS include upper and lower airway obstruction and restrictive pulmonary disease, which can lead to chronic rhinosinusitis or chronic ear infections, recurrent upper and lower respiratory tract infections, obstructive sleep apnoea, impaired exercise tolerance, and respiratory failure. This review provides a detailed overview of the ENT and respiratory manifestations that can occur in patients with MPS and discusses the issues related to their evaluation and management.

Anaesthesia and airway management in mucopolysaccharidosis

This paper provides a detailed overview and discussion of anaesthesia in patients with mucopolysaccharidosis (MPS), the evaluation of risk factors in these patients and their anaesthetic management, including emergency airway issues. MPS represents a group of rare lysosomal storage disorders associated with an array of clinical manifestations. The high prevalence of airway obstruction and restrictive pulmonary disease in combination with cardiovascular manifestations poses a high anaesthetic risk to these patients. Typical anaesthetic problems include airway obstruction after induction or extubation, intubation difficulties or failure [can't intubate, can't ventilate (CICV)], possible emergency tracheostomy and cardiovascular and cervical spine issues. Because of the high anaesthetic risk, the benefits of a procedure in patients with MPS should always be balanced against the associated risks. Therefore, careful evaluation of anaesthetic risk factors should be made before the procedure, involving evaluation of airways and cardiorespiratory and cervical spine problems. In addition, information on the specific type of MPS, prior history of anaesthesia, presence of cervical instability and range of motion of the temporomandibular joint are important and may be pivotal to prevent complications during anaesthesia. Knowledge of these risk factors allows the anaesthetist to anticipate potential problems that may arise during or after the procedure. Anaesthesia in MPS patients should be preferably done by an experienced (paediatric) anaesthetist, supported by a multidisciplinary team (ear, nose, throat surgeon and intensive care team), with access to all necessary equipment and support.

Pulmonary artery sling: a rare cause of tracheomalacia in the adult

Tracheomalacia (TM) is an under-recognized condition that presents with nonspecific symptoms such as dyspnea, cough, and recurrent infections. Frequently, patients with this condition are misdiagnosed with more prevalent diseases such as asthma and chronic obstructive pulmonary disease. We report a case of a 29-year-old woman with long-standing, mild, persistent asthma characterized by dyspnea and cough, who experienced acute and severe worsening of her symptoms after the cesarean section for the delivery of her third child. She was initially treated with bronchodilators and oral corticosteroids without improvement. She underwent further evaluation with a chest computed tomographic scan and a flexible bronchoscopy, which revealed focal TM in the distal trachea secondary to chronic extrinsic compression due to a pulmonary vascular sling. We discuss her subsequent evaluation and management.

Multidetector-row Computed Tomography of Diffuse Tracheal Disease: Pictorial Review

Diffuse tracheal diseases are uncommon and may mimic asthma or other forms of chronic obstructive lung disease. Bronchoscopy is usually definitive in establishing a diagnosis and assessing the severity of diffuse tracheal disease. However, advances in multidetector-row computed tomography (MDCT) technology allow for rapid acquisition time and generation of high-quality multiplanar reconstructions and virtual bronchoscopic images, making MDCT evaluation of suspected or known tracheal disease the noninvasive examination of choice. The MDCT findings of the various diseases that diffusely affect the trachea may be highly suggestive of 1 particular disease or narrow the differential diagnosis to a few possibilities. Moreover, MDCT imaging of the chest can help identify associated lung disease or complications of diffuse tracheal disease such as pneumonia or atelectasis. This pictorial review illustrates the MDCT appearances of the more common diffuse tracheal diseases.

Surgery for Tracheobronchomalacia

Tracheobronchomalacia (TBM) refers to a weakening of the anterior tracheal rings leading to splaying and collapse of the central airways. In this report, we review the treatment of TBM, including preoperative workup, intraoperative anesthesia management, and surgical technique for posterior splinting tracheobronchoplasty. Imperative in the preoperative preparation is a stent trial in which an airway stent is placed to temporarily relieve the TBM and reassess for improvement in symptoms. Definitive therapy is then carried out with posterior splinting tracheoplasty or tracheobronchoplasty. Surgical results are generally excellent with the majority of patients having significant improvements in breathing.

[Tracheobronchomalacia in adults: breakthroughs and controversies]

Tracheobronchomalacia (TBM) in adults is a disease defined by a reduction of more than 50% of the airway lumen during expiration. It encompasses many etiologies that differ in their morphologic aspects, pathophysiological mechanisms and histopathologies. TBM is encountered with increasing frequency, as it is more easily diagnosed with new imaging techniques and diagnostic bronchoscopy, as well as because of its frequent association with Chronic Obstructive Pulmonary Disease (COPD), which represents the most frequent etiology for acquired TBM in adults. A distinction between TBM in association with failure of the cartilaginous part of the airways and TBM affecting only the posterior membranous part is emerging since their physiopathology and treatment differ. The therapeutic management of TBM should be as conservative as possible. Priority should be given to identification and treatment of associated respiratory diseases, such as asthma or COPD. Surgery addressing extrinsic compression (thyroid goiter or tumor, for example) may be necessary. Noninvasive ventilation can be considered in patients with increasing symptoms. Endoscopic options, such as the placement of stents, should only be used as palliative or temporary solutions, because of the high complication rates. Symptomatic improvement after stenting might be helpful in selecting patients in whom a surgical management with tracheobronchoplasty can be useful.

Tracheobronchomalacia in children: review of diagnosis and definition

Tracheobronchomalacia is characterised by excessive airway collapsibility due to weakness of airway walls and supporting cartilage. The standard definition requires reduction in cross-sectional area of at least 50% on expiration. However, there is a paucity of information regarding the normal range of central airway collapse among children of varying ages, ethnicities and genders, with and without coexisting pulmonary disease. Consequently, the threshold for pathological collapse is considered somewhat arbitrary. Available methods for assessing the airway dynamically--bronchoscopy, radiography, cine fluoroscopy, bronchography, CT and MR--have issues with reliability, the need for intubation, radiation dose and contrast administration. In addition, there are varying means of eliciting the diagnosis. Forced expiratory manoeuvres have been employed but can exaggerate normal physiological changes. Furthermore, radiographic evidence of tracheal compression does not necessarily translate into physiological or functional significance. Given that the criteria used to make the diagnosis of tracheobronchomalacia are poorly validated, further studies with larger patient samples are required to define the threshold for pathological airway collapse.

Nasal versus oronasal raised volume forced expirations in infants--a real physiologic challenge

Raised volume rapid thoracoabdominal compression (RTC) generates forced expiration (FE) in infants typically from an airway opening pressure of 30 cm H(2)O (V(30)). We hypothesized that the higher nasal than pulmonary airway resistance limits forced expiratory flows (FEF(%)) during (nasal) FE(n), which an opened mouth, (oronasal) FE(o), would resolve. Measurements were performed during a brief post-hyperventilation apnea on 12 healthy infants aged 6.9-104 weeks. In two infants, forced expiratory (FEFV) flow volume (FV) curves were generated using a facemask that covered the nose and a closed mouth, then again with a larger mask with the mouth opened. In other infants (n = 10), the mouth closed spontaneously during FE. Oronasal passive expiration from V(30) generated either the inspiratory capacity (IC) or by activating RTC before end-expiration, the slow vital capacity ((j) SVC). Peak flow (PF), FEF(25), FEF(50), FEF(25-75), FEV(0.4), and FEV(0.5) were lower via FE(n) than FE(o) (P < 0.05), but the ratio of expired volume at PF and forced vital capacity (FVC) as percent was higher (P < 0.05). FEF(75), FEF(85), FEF(90), FVC as well as the applied jacket pressures were not different (P > 0.05). FEFV curves generated via FE(o) exhibited higher PF than FV curves of IC (P < 0.05); PF of those produced via FE(n) were not different from FV curves of IC (P > 0.05) but lower than those of (j) SVC (P < 0.05). In conclusion, the higher nasal than pulmonary airways resistance unequivocally affects the FEFV curves by consistently reducing PF and decreases mid-expiratory flows. A monitored slightly opened mouth and a gentle anterior jaw thrust are physiologically integral for raised volume RTC in order to maximize the oral and minimize nasal airways contribution to FE so that flow limitation would be in the pulmonary not nasal airways.

Computed tomographic imaging of the airways in COPD and asthma

Computed tomography (CT) is the modality of choice for imaging the airways. Volumetric data sets with isotropic spatial resolution based on multidetector thin-section CT with overlapping reconstruction should be used. Chronic obstructive pulmonary disease and asthma are the 2 most common disease entities that are defined by airflow obstruction. The morphologic correlates of airway changes are dilation of the lumen, thickening of the wall, visibility of small airways due to mucus or edema, air trapping, hypoxic vasoconstriction, and collapsibility. To assess air trapping, additional expiratory low-dose scans are recommended. In clinical routine, these findings are visually assessed and should be routinely reported. However, the interobserver variability is high, and there is a clear need for objective software-based measurements. The development of such tools is challenging, and they are just becoming available on a broader scale. Novel techniques based on dual-energy CT aim to measure iodine distribution maps to assess pulmonary perfusion as well as the distribution of inhaled xenon gas to assess the distribution and time course of pulmonary ventilation. However, these techniques are still being investigated in clinical studies. This review will provide an overview of CT for the diagnosis of chronic obstructive pulmonary disease and asthma, its role in phenotyping these diseases, and the measurement of disease severity and functional compromise.

Psittacosis infection and tracheobronchomalacia in a patient undergoing thyroidectomy

A 34-year-old woman with papillary thyroid carcinoma underwent total thyroidectomy with central and lateral lymphadenectomy. Immediate airway compromise required re-intubation immediately after surgery. Marked tracheal and bronchial collapse of greater than 50% of the lumen indicated tracheobronchomalacia. Subsequent attempts at extubation failed over the next week. The patient soon developed evidence of a lower respiratory tract infection. Empirical treatment with penicillins was unsuccessful. A clinical suspicion of chlamydia infection prompted initiation of macrolide treatment followed by resolution of both the patient's respiratory infection and tracheobronchomalacia. Serology returned positive for Chlamydophila psittaci infection. It later transpired that the patient had symptoms of an upper respiratory tract infection just prior to surgery. This case demonstrates an interesting and unreported cause of tracheobronchomalacia as well as providing a good lesson on the importance of preoperative screening for infection.

Conservative management of canine tracheal collapse with stanozolol: a double blinded, placebo control clinical trial

The objective of this study is to determine the efficacy of stanozolol in the treatment of tracheal collapse (TC) in dogs, which is the analogous disease to tracheomalacia (TM) in humans. Twenty-two dogs with endoscopically confirmed and graded TC were enrolled into five groups. Groups S1 (n=5), S2 (n=5) and S3 (n=4) with grade 1, 2 and 3 TC, respectively, received stanozolol orally for 75 days, while groups P1 (n=4) and P2 (n=4) with grade 1 and 2 TC, respectively, received placebo. The clinical score was evaluated every 15 days, whereas TC grade was reassessed at the end of the experiment. Clinical improvement was detected from the 30th day in S2 and S3 group dogs and from the 45th day in S1 group dogs and continued until the end of the experiment. Also, statistically significant differences were seen between S2 and P2 dogs from the 30th day, and between S1 and P1 dogs from the 60th day, and continued until the end of the study. Amelioration of the TC grade was seen in 13 of 14 (92.9%) dogs, which received stanozolol. Of the 14 dogs, 57.1% were cured and 35.8% demonstrated a less severe TC grade, while only one dog (7.1%) did not improve at all. Stanozolol seems to be an effective drug in the management of canine TC and it may have potential for use in humans with TM.

Tracheobronchomalacia in adults

Severe, diffuse tracheobronchomalacia (TBM) is an underrecognized cause of dyspnea, recurrent respiratory infections, cough, secretion retention, and even respiratory insufficiency. Patients often have comorbidities, such as asthma or chronic obstructive pulmonary disease, and inappropriate treatment for these conditions may precede eventual recognition of TBM by months or years. Most of these patients have an acquired form of TBM in which the etiology in unknown. Diagnosis of TBM is made by airway computed tomography scan and flexible bronchoscopy with forced expiration. The prevailing definition of TBM as a 50% reduction in cross-sectional area is nonspecific, with a high proportion of healthy volunteers meeting this threshold. The clinically significant threshold is complete or near-complete collapse of the airway. Airway stenting may treat TBM, although complications resulting from indwelling prostheses often limit the durability of stents. Surgical stabilization of the airway by posterior splinting (tracheobronchoplasty) effectively and permanently corrects malacic airways. Proper surgical selection is facilitated by a short-term stent trial.

Elastic properties of the central airways in obstructive lung diseases measured using anatomical optical coherence tomography

RATIONALE

Our understanding of how airway remodeling affects regional airway elastic properties is limited due to technical difficulties in quantitatively measuring dynamic, in vivo airway dimensions. Such knowledge could help elucidate mechanisms of excessive airway narrowing.

OBJECTIVES

To use anatomical optical coherence tomography (aOCT) to compare central airway elastic properties in control subjects and those with obstructive lung diseases.

METHODS

After bronchodilation, airway lumen area (Ai) was measured using aOCT during bronchoscopy in control subjects (n = 10) and those with asthma (n = 16), chronic obstructive pulmonary disease (COPD) (n = 9), and bronchiectasis (n = 8). Ai was measured in each of generations 0 to 5 while airway pressure was increased from -10 to 20 cm H(2)O. Airway compliance (Caw) and specific compliance (sCaw) were derived from the transpulmonary pressure (Pl) versus Ai curves.

MEASUREMENTS AND MAIN RESULTS

Caw decreased progressively as airway generation increased, but sCaw did not differ appreciably across the generations. In subjects with asthma and bronchiectasis, Caw and sCaw were similar to control subjects and the Pl-Ai curves were left-shifted. No significant differences were observed between control and COPD groups.

CONCLUSIONS

Proximal airway elastic properties are altered in obstructive lung diseases. Although central airway compliance does not differ from control subjects in asthma, bronchiectasis, or COPD, Ai is lower in asthma and the Pl-Ai relationship is left-shifted in both asthma and bronchiectasis, suggesting that airways are maximally distended at lower inflating pressures. Such changes reflect alteration in the balance between airway wall distensibility and radial traction exerted on airways by surrounding lung parenchyma favoring airway narrowing. Clinical trial registered with Australian New Zealand Clinical Trials Registry (ACTRN12607000624482).

Interventional bronchoscopy from bench to bedside: new techniques for central and peripheral airway obstruction

This article discusses how basic scientific concepts, based on a greater understanding of airway physiology, support the development and dissemination of multidimensional classification systems for tracheal stenosis, expiratory central airway collapse, and innovative interventional bronchoscopic procedures for patients with asthma and chronic obstructive pulmonary disease.

Airway stents

Stents are used for palliation of symptoms of central airway obstruction caused by either malignant or benign conditions. Stents may be applied for maintaining airway patency after dilatation of postinflammatory and infectious strictures, for airway dehiscence after lung transplantation, and for the management of tracheobronchomalacia. Fistulas between trachea or bronchi and the esophagus and dehiscence of pneumonectomy stump can be protected with covered stents. Choice of stent depends on careful patient selection, characteristics of airway stenosis, physician's expertise, and availability of equipment. Placement of tube stents requires rigid bronchoscopy and dilatation of strictures beforehand, whereas metal stents can be applied using a flexible bronchoscope. Advantages and disadvantages of commonly used airway stents are discussed.

Emerging technologies for the thorax: indications, management and complications

The field of interventional pulmonology has rapidly expanded to include the management and treatment of complex diseases of the chest. The management of central airway obstruction, pleural disease diagnosis, treatment and palliation, advanced bronchoscopic techniques to aid in the diagnosis of lung cancer and innovative therapies to treat asthma and COPD have all emerged over the past decade. As astute clinicians, we are all aware of the risks and benefits of using these therapies to treat our patients. In order to appropriately treat and manage these often complex medical situations, the physician should have an expert knowledge of all available modalities, the expertise to safely perform the procedure and the ability to minimize the risk of and manage the associated complications that may arise. In this chapter we review and update some of the bronchoscopic and pleural interventions offered by interventional pulmonologists as well as the associated complications and management.

[Tracheobronchomalacia]

Tracheobronchomalacia is a central airway disease characterised by weakness of the wall and dynamic decrease in the tracheal lumen and the large bronchi, particularly while exhaling. It is more common in middle age and the elderly with previous exposure to cigarettes. It causes chronic symptoms such as cough, dyspnea, increase in recurrent infections, and poor secretion management, but it can also progress to chronic respiratory failure and death. It is usually confused with other common diseases like chronic obstructive pulmonary disease (COPD) or asthma. Its causes can be congenital or acquired and its diagnosis involves the dynamic assessment of the airway with tomography and fibrobronchoscopy. It is classified as mild, moderate or severe depending on the degree of collapse of the airway when exhaling. Management consists of a primary phase, in which concomitant diseases must be controlled, such as COPD, asthma or gastro-oesophageal reflux. In diffuse moderate to severe symptomatic tracheobronchomalacia tracheobronchoplasty must be considered with strengthening of the posterior wall. Silicone and "Y" stents can be used to identify patients who could potentially benefit from surgical treatment as well as being used for the definitive symptomatic treatment with high surgical risk. More prospective studies need to be done in order to standardise certain common criteria for the management of this usually under-diagnosed disease.