Description of a multidimensional classification system for patients with expiratory central airway collapse

Bronchoscopy for refractory/unexplained cough with mucus

INTRODUCTION

Refractory/unexplained cough (RUCC) is typically associated with throat symptoms and a dry cough. Some patients attending specialist cough clinics however, report sputum production (>1 tablespoon daily) and atypical sensations (urge-to-cough in chest). Bronchoscopy findings in this specific cohort have rarely been described.

AIMS

We aimed to evaluate bronchoscopy, bronchoalveolar lavage (BAL) cell differential and microbiology findings in RUCC with mucus production.

METHODS

We retrospectively reviewed case notes, procedure results and treatment of patients undergoing bronchoscopy for RUCC with more than a tablespoon of sputum daily.

RESULTS

Data were included from 54 patients with RUCC, normal or trivial findings on CT (Computerised Tomography) imaging and no response to guideline-directed treatment of their cough. Most (84%) patients had BAL neutrophilia and excessive dynamic airway collapse (EDAC) was seen in 31%. Treatment strategies in these patients differed to those adopted in typical RUCC associated with a dry cough. Management was influenced or changed in 48/54 (89%) of the patients undergoing bronchoscopy.

CONCLUSIONS

Bronchoscopy provides high diagnostic value in RUCC with mucus production (>1 tbsp daily), identifying specific treatable traits including neutrophilic airway inflammation and EDAC.

Excessive Dynamic Airway Collapse Severity Scoring System: A Call Out for an Overall Severity Determination

BACKGROUND

Severe excessive dynamic airway collapse (EDAC) is defined as airway narrowing due to posterior wall protrusion into the airway lumen, >90%. We aimed to establish an overall severity score to assess severe EDAC and the need for subsequent intervention.

METHODS

A retrospective study of patients who underwent dynamic bronchoscopy for evaluation of expiratory central airway collapse between January 2019 and July 2021. A numerical value was given to each tracheobronchial segmental collapse: 0 points (<70%), 1 point (70% to 79%), 2 points (80% to 89%), and 3 points (>90%) to be added for an overall EDAC severity score per patient. We compared the score among patients who underwent stent trials (severe EDAC) and those who did not. Based on the receiver operating characteristics curve, a cutoff total score to predict severe EDAC was calculated.

RESULTS

One hundred fifty-eight patients were included. Patients were divided into severe (n = 60) and nonsevere (n = 98) EDAC. A cutoff of 9 as the total score had a sensitivity of 94% and a specificity of 74% to predict severe EDAC, based on an area under the curve 0.888 (95% CI: 0.84, 0.93; P < 0.001).

CONCLUSION

Our EDAC Severity Scoring System was able to discern between severe and nonsevere EDAC by an overall score cutoff of 9, with high sensitivity and specificity for predicting severe disease and the need for further intervention, in our institution.

Successful step-by-step diagnosis and management of expiratory central airway collapse

A 45-year-old woman with recurrent dyspnea for 40 years was previously diagnosed with bronchial asthma and spasmodic dysphonia. On admission, the patient was diagnosed with expiratory central airway collapse (ECAC) due to expiratory dynamic airway collapse based on radiographic examination, chest computed tomography, and bronchoscopy. After continuous positive airway pressure and temporal airway stenting, surgical tracheobronchoplasty and tracheal membranous portion reinforcement using polypropylene mesh successfully relieved the respiratory symptoms. In patients with airway obstructive disease refractory to conventional therapies, ECAC should be considered.

Detection and diagnosis of large airway collapse: a systematic review

Large airway collapse (LAC) is a frequently encountered clinical problem, caused by tracheobronchomalacia +/− excessive dynamic airway collapse, yet there are currently no universally accepted diagnostic criteria. We systematically reviewed studies reporting a diagnostic approach to LAC in healthy adults and patients, to compare diagnostic modalities and criteria used. Electronic databases were searched for relevant studies between 1989 and 2019. Studies that reported a diagnostic approach using computed tomography (CT), magnetic resonance imaging or flexible fibreoptic bronchoscopy were included. Random effects meta-analyses were performed to estimate the prevalence of LAC in healthy subjects and in patients with chronic obstructive airway diseases. We included 41 studies, describing 10 071 subjects (47% female) with a mean±sd age of 59±9 years. Most studies (n=35) reported CT findings, and only three studies reported bronchoscopic findings. The most reported diagnostic criterion was a ≥50% reduction in tracheal or main bronchi calibre at end-expiration on dynamic expiratory CT. Meta-analyses of relevant studies found that 17% (95% CI: 0–61%) of healthy subjects and 27% (95% CI: 11–46%) of patients with chronic airways disease were classified as having LAC, using this threshold. The most reported approach to diagnose LAC utilises CT diagnostics, and at a threshold used by most clinicians (i.e., ≥50%) may classify a considerable proportion of healthy individuals as being abnormal and having LAC in a quarter of patients with chronic airways disease. Future work should focus on establishing more precise diagnostic criteria for LAC, relating this to relevant physiological and disease sequelae.

CT is mostly used to diagnose LAC, and at a threshold used by most clinicians (i.e. ≥50%) that would classify a large proportion of healthy individuals as being abnormal and LAC in a quarter of patients with chronic airway diseaseshttps://bit.ly/3izAuSk

Airway Abnormalities in Adult Mucopolysaccharidosis and Development of Salford Mucopolysaccharidosis Airway Score

(1) Background: Mucopolysaccharidoses (MPS) are a heterogeneous group of lysosomal storage disorders caused by the absence of enzymes required for degradation of glycosaminoglycans (GAGs). GAGs deposition in tissues leads to progressive airway narrowing and/or tortuosity. Increased longevity of patients has posed newer problems, especially the airway. This study aims to characterise various airway abnormalities in adult MPS from a regional centre and proposes a method to quantify the severity of the airway disease. (2) Methods: Retrospective analysis by case notes review, clinical examination, endoscopy, cross-sectional imaging, 3-dimensional reconstruction, and physiological investigations were used to assess the airway abnormalities. Quantitative assessment of the airway severity was performed a validated questionnaire of 15 parameters to derive Salford Mucopolysaccharidosis Airway Score (SMAS). (3) Results: Thirty-one adult MPS patients (21M/ 9F; median 26.7 years; range 19–42 years) were reviewed. There were 9 MPS I, 12 MPS II, 2 MPS III, 5 MPS IV, 2 MPS VI, and 1 MPS VII. Airway abnormalities in each MPS type are described. Patients scoring more than 35 on SMAS had some form of airway intervention. The area under curve of 0.9 was noted at a score of 25, so SMAS more than 25 may predict a difficult airway and potential to have complications. Pearson’s correlation between SMAS and height, weight, BMI were poor (p < 0.05). (4) Conclusions: Airway abnormalities in adult MPS are varied and complex. Assessment of the airway should be holistic and include multiple parameters. An objective multidimensional score such as SMAS may help to predict and manage difficult airways warranting further investigation and validation.

Therapeutic bronchoscopy for central airway diseases

Over the past century rigid bronchoscopy has been established as the main therapeutic means for central airway diseases of both benign and malignant aetiology. Its use requires general anaesthesia and mechanical ventilation usually in the form of manual or high-frequency jet ventilation. Techniques applied to regain patency of the central airways include mechanical debulking, thermal ablation (laser, electrocautery and argon plasma coagulation) and cryo-surgery. Each of these techniques have their advantages and limitations and best results can be attained by combining different modalities according to the type, location and extent of the airway blockage. If needed, deployment of airway endoprostheses (stents), as either fixed-diameter silicone or self-expandable metal stents, may preserve the airways patency often at the cost of several complications. Newer generation of customised stents either three-dimensional printed or drug-eluting stents constitute a promise for improved safety and efficacy results in the near future. Treating central disease of benign or malignant aetiology, foreign body aspiration or massive bleeding in the airways requires a structured approach with combined techniques, a dedicated team of professionals and experience to treat eventual complications. Specific training and fellowships in interventional pulmonology should therefore be offered to those who wish to specialise in this field.

A successful surgical tracheobronchoplasty in a case of expiratory collapse of central airways associated with tracheobronchomalacia in a severely deformed single lung patient

A 67-year-old male with a severe body deformity and a total collapse of the left lung due to infantile paralysis was admitted to a regional hospital for a spinal fracture. He suffered from cardiopulmonary arrest during the hospitalization. Although extubation was tried several times after resuscitation, he went into cardiopulmonary arrest repeatedly. The expiratory collapse of the central airways due to tracheobronchomalacia was suspected, requiring tracheostomy with persistent positive pressure ventilation. He was transferred to our hospital after several unsuccessful endobronchial interventions. Severe tracheobronchomalacia was diagnosed with dynamic bronchoscopy, and surgical tracheobronchoplasty using a polypropylene mesh was performed. A modified surgical approach was utilized to stabilize the intraoperative respiratory status in this particular patient with a severely deformed body and a single lung. Consequently, the tracheobronchoplasty was completed without intraoperative complications. The postoperative course was also uneventful, and the patient was ventilator-free on postoperative day 7.

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.

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.

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.

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.

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.

Tracheal collapse diagnosed by multidetector computed tomography: evaluation of different image analysis methods

Background: The gold standard for diagnosing excessive tracheal collapse is still evaluation during bronchoscopy. Today, multidetector computed tomography (MDCT) is used to confirm a suspicion of abnormal tracheal collapse. There is no gold standard for computed tomography (CT) image analysis of tracheal collapse.

Purpose: To evaluate four different methods for the diagnosis of tracheal collapse using the images obtained through MDCT to help clinicians evaluate the images in daily practice.

Objectives: 374 consecutive high-resolution CT scans with full inspiratory and end-expiratory CT scans were retrospectively analyzed.

Methods: The images were analyzed in four different ways. The degree of collapse was based on cross-sectional areas of individual locations or volumes of entire regions: (1) 1 cm above the carina, (2) the level of maximal collapse of the trachea, (3) the entire region from the carina to the thoracic inlet, and (4) the trachea and bronchial region as defined by the software.

Results: We compared three existing and one new method for image analysis of tracheal collapse by MDCT. The prevalence of tracheal collapse varied from 10.7% to 19.5% in this cohort of patients suffering from mixed lung diseases when using an expiratory collapse of ≥50% as a threshold. The four methods were comparable with highly significant Pearsons correlation coefficients (0.764–0.856). However, the four methods identified different patients with collapse of ≥50%. There was no correlation between symptoms and the degree of collapse.

Conclusion: The different methods identify tracheal collapse in different patients. Hence, the diagnosis of excessive tracheal collapse can not rely solely on MDCT images. Generally, there is a poor correlation between symptoms and the degree of collapse in the different methods. However, when using the maximal collapse, there is some correlation with symptoms. When in doubt regarding the diagnosis, further investigations, such as bronchoscopy, should be carried out.

Manometry Optimized Positive Expiratory Pressure (MOPEP) in Excessive Dynamic Airway Collapse (EDAC)

BACKGROUND

Positive expiratory pressure(PEP) breathing modalities are commonly prescribed in obstructive lung diseases, however practical methods of airway pressures(AP) quantification for therapeutic efficacy are lacking. Excessive dynamic airway collapse(EDAC) is characterized by expiratory central airway collapse leading to dyspnea and poor quality of life(QoL), with limited therapeutic options.

PURPOSE

To measure AP and exertional dyspnea in EDAC patients during normal breathing and with use of pursed-lip breathing(PLB), nasal PEP device(nPEP), and oral-PEP valve(oPEP) during rest and exercise using an Esophageal Manometer.

METHODS

EDAC patients exercised on a bicycle ergometer sequentially using normal breathing, PLB, nPEP, and oPEP for five-minute intervals. AP's were measured by continuous topographic upper airway manometry. Pre- and post-exercise BORG dyspnea scores were recorded and QoL measured with the St. George's respiratory questionnaire(SGRQ-C). The most effective and patient-preferred PEP modality was prescribed for daily activities and SGRQ-C repeated after one week.

RESULTS

Three women with symptomatic EDAC participated. Expiratory laryngopharyngeal AP's during exercise with normal breathing, PLB, nPEP and oPEP in patient-1 were 1.7, 14, 4.5, and 7.3 mmHg, in patient-2; 2.3, 8, 8.3, and 12 mmHg, and in patient-3; 1, 15, unobtainable, and 9 mmHg, respectively. Maximal reduction in BORG scores occurred with PLB in patient 1 and with oPEP in patients 2 and 3. After 1 week mean SGRQ-C scores declined by 17-points.

CONCLUSIONS

Upper airway manometry directly measures laryngopharyngeal pressures during rest and exercise and can be used to select and optimize PEP breathing techniques to improve respiratory symptoms in EDAC patients.

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.

Electronic supplementary material

The online version of this article (10.1186/s12931-017-0646-2) contains supplementary material, which is available to authorized users.

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.

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.

Successful High Flow Nasal Oxygen Therapy for Excessive Dynamic Airway Collapse: A Case Report

Excessive dynamic airway collapse (EDAC) is a disease entity of excessive reduction of the central airway diameter during exhalation, without cartilage collapse. An 80-year-old female presented with generalized edema and dyspnea at our hospital. The patient was in a state of acute decompensated heart failure due to pneumonia with respiratory failure. We accordingly managed the patient with renal replacement therapy, mechanical ventilation and antibiotics. Bronchoscopy confirmed the diagnosis of EDAC. We scheduled extubation after the improvement of pneumonia and heart condition. However, extubation failure occurred due to hypercapnic respiratory failure with poor expectoration. Her EDAC was improved in response to high flow nasal oxygen therapy (HFNOT). Subsequently, the patient was stabilized and transferred to the general ward. HFNOT, which generates physiologic positive end expiratory pressure (PEEP) effects, could be an alternative and effective management of EDAC. Further research and clinical trials are needed to demonstrate the therapeutic effect of HFNOT on EDAC.

Excessive Dynamic Airway Collapse: An Unexpected Contributor to Respiratory Failure in a Surgical Patient

Central airway collapse plays a significant, underrecognized role in respiratory failure after extubation of critically ill patients. Historically, airway collapse has been attributed to tracheomalacia (TM), softening of the cartilage in the trachea and other large airways. More recently, excessive dynamic airway collapse (EDAC) has been described as a distinct process unrelated to a loss of cartilaginous airway support. EDAC is caused by the posterior wall of the trachea bulging forward and causing airway obstruction during exhalation. This process is exaggerated when intrathoracic pressure is increased and results in a clinical picture of coughing, difficulty clearing secretions, dyspnea, and stridor. The increased use of computerized tomography and fiberoptic bronchoscopy has identified varying degrees of EDAC and TM in both symptomatic and asymptomatic individuals. This has led to renewed consideration of airway collapse and the different processes that contribute to it. Here we describe a 43-year-old morbidly obese patient who failed repeated attempts at extubation after elective hysterectomy. We will discuss the processes of EDAC and TM, describe how this condition contributed to this patient's respiratory failure, and review diagnosis and management options.

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.

The "forgotten zone": acquired disorders of the trachea in adults

The upper airway is generally defined as the air passage segment that extends between the naso- or oropharynx and the carina. The longest segment of the upper airway—the trachea—begins at the inferior portion of the larynx and extends to the branch point of the main carina. The trachea has the potential to be a “forgotten zone” in differential diagnoses, as pathological processes involving this portion may not receive prominent clinical consideration in disorders presenting with respiratory symptoms and signs. Unlike the oropharynx, this anatomical area is beyond visualization on routine inspection; unlike the mediastinum and lung fields, it is a potential “blind spot” on initial, plain radiographic examination of the chest. Nonetheless, the adult trachea is affected by a number of primary disorders and is also a target organ of a variety of systemic diseases. This review will focus on both primary and systemic diseases involving the adult trachea with specific attention to their clinical manifestations and diagnostic hallmarks.

Newer CT applications and their alternatives: what is appropriate in children?

Innovations in image acquisition and reconstruction technologies have greatly expanded the range of CT applications available in the routine clinical setting. CT images of sub-millimeter resolution can now be acquired of entire body regions in a few seconds or even sub-second time, allowing depiction of fine anatomical detail uncompromised by motion artifact. With sophisticated visualization software, image data can be processed into multiplanar, volume-rendered, cine and other formats to better display anatomical abnormalities and facilitate newer applications such as CT angiography, enterography, urography, tracheobronchography and cardiac CT. Newer applications including dual-energy material decomposition CT are furthering the transition of CT from a purely morphological to a combined anatomical, functional and metabolic imaging technique. These newer applications have largely been pioneered in adult populations, and heightened concern of the risk of carcinogenesis from ionizing radiation tempers dissemination of their use in children. Similar information can often be gleaned from alternative imaging modalities without ionizing radiation exposure, such as MRI and US, and what is most appropriate in children will depend on relative diagnostic efficacy, cost, availability and local expertise.

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.

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.

Bibliography. Current world literature

This bibliography is compiled by clinicians from the journals listed at the end of this publication. It is based on literature entered into our database between 1 November 2007 and 31 October 2008 (articles are generally added to the database about two and a half months after publication). In addition, the bibliography contains every paper annotated by reviewers; these references were obtained from a variety of bibliographic databases and published between the beginning of the review period and the time of going to press. The bibliography has been grouped into topics that relate to the reviews in this issue.

Morphometric bronchoscopy in adults with central airway obstruction: case illustrations and review of the literature

The severity of airway narrowing impacts ventilatory function, quality of life, and choice of therapy for patients with central airway obstruction. The quantification of airway caliber remains a subjective estimate that depends on patient positioning, technique, and operator experience. In this article, we describe how morphometric bronchoscopy, a software processing method whereby bronchoscopic digital images are analyzed in order to measure airway lumen diameter, can be used to objectively quantify the degree of airway narrowing in adult patients with central airway obstruction.