Excessive Dynamic Airway Collapse causes posterior tracheal membrane collapse with ≥50% lumen narrowing, diagnosed effectively by bronchoscopy, and treated with positive airway pressure.
Excessive Dynamic Airway Collapse (EDAC) should be considered in the differential diagnosis for patients with persistent dyspnea and wheeze that worsens in the supine position.
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An 84-year-old female, with a background of hypertension, coronary artery disease, Grade II Barett’s esophagus, came to the emergency room with complaints of sudden onset of breathlessness worsening in supine position, cough with expectoration for 3 days, and desaturation up to 85% in room air for 2 days. In view of biphasic wheeze and desaturation, the patient was admitted to the high dependency unit. She was diagnosed to have Influenza A pneumonia, associated with Type II Respiratory failure. She was treated with anti-viral and non-invasive ventilation (NIV). She improved symptomatically and was shifted to the ward. While her other symptoms resolved, she persistently had cough and breathlessness, which was more on lying down. Her attenders also gave a brief history of snoring. On auscultation, inspiratory wheeze was persistent. Computed tomography (CT)-chest and ECHO were done to further evaluate the condition. ECHO revealed the following: Concentric left ventricular (LV) hypertrophy No regional wall movement abnormality Normal LV systolic function (ejection fraction-62%) Grade I LV diastolic dysfunction Normal right ventricular systolic function No Aortic stenosis (AS)/Aortic regurgitation (AR) Mild Mitral regurgitation (MR)/Tricuspid regurgitation (TR) Normal pulmonary artery pressure No evidence of pericardial effusion/clot/vegetation. An image of a section from the CT- Chest of the patient has been shared below Figure 1:Figure 1: Computed tomography chest imageQuestion-1 What is the relevant finding seen in the CT-Chest image? Answer 1 Collapse of the posterior membrane of the trachea resulting in luminal narrowing. Question-2 What is the probable diagnosis? Answer 2 Excessive Dynamic Airway Collapse (EDAC). Question-3 Describe how we can evaluate and treat this patient’s condition. Answer 3 EDAC is defined as the pathological collapse and narrowing of the airway lumen by 50% or more of the sagittal diameter, which occurs as a result of laxity of the posterior wall membrane with intact cartilage.1 Patients with EDAC may be asymptomatic during most hours of the day, but may also present with complaints of episodic dyspnea, persistent wheeze despite medications, chronic dry cough, and may at times even present with severe respiratory failure.2 While evaluating patients with EDAC, three crucial investigations to look at include pulmonary function tests, CT-chest, and bronchoscopy. In Spirometry, a useful marker to consider would be the Empey’s Index to diagnose upper airway obstruction, which is defined as the ratio of forced expiratory volume in 1 s to the Peak expiratory flow rate. A ratio of 10 or more is suggestive of an obstruction. The Empey’s Index is directly proportional to the extent of obstruction. In EDAC, the ratio is expected to be more than 10; however, due to variability in the obstruction extent, it may not reflect on the spirometry values.3 On a CT-Chest image, patient’s lumen may appear narrowed. However, since the compression is dynamic, the obstruction may be relieved at the time of CT imaging and may therefore give us false-negative results. Bronchoscopy would allow direct imaging of the pathway and when doubtful, also gives us the leverage to induce the dynamic compression by asking the patient to exert. Therefore, bronchoscopy would be more confirmatory of the diagnosis.4 The most appropriate differential diagnosis for this condition is tracheobronchomalacia. As the name suggests, tracheobronchomalacia refers to the luminal narrowing in the airway caused due to weakness in the cartilages. Invariably, CT-chest imaging would reveal collapse of the anterior wall, resulting in airway narrowing, unlike in EDAC, where the posterior wall is involved. A bronchoscopy would help clench the diagnosis of tracheobronchomalacia. EDAC is typically treated with bronchodilators and mucolytics to address the issue of persistent cough. EDAC responds well to a positive airway pressure device. The PEEP provided by the positive airway pressure device would help keep the airway patent and prevent collapse. In extremes of condition, where the breathlessness episodes are more frequent and cause frequent exacerbations Y-stenting procedures may be considered.5 A failure with stenting may also lead to consideration of surgical interventions such as airway splinting and tracheal resection.6 Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Aprameya et al. (Thu,) reported a other. Excessive Dynamic Airway Collapse causes posterior tracheal membrane collapse with ≥50% lumen narrowing, diagnosed effectively by bronchoscopy, and treated with positive airway pressure.