Diagnostic Considerations
The differential diagnosis of tracheomalacia includes laryngomalacia, subglottic stenosis, congenital cysts, vocal cord paralysis, and hypocalcemic tetany. Complications include problems with acute airway obstruction and perioperative morbidity and mortality.
According to a 2005 study by Boogaard, when pediatric pulmonologists diagnosed airway malacia (on the basis of symptoms, history, and lung function) prior to bronchoscopy, a correct diagnosis was made in 74% of the cases. [9] However, in 52% of the diagnoses of airway malacia, the diagnosis was not suspected prior to bronchoscopy. Children with tracheomalacia present with atypical and variable clinical features; considerable overlap occurs with features of allergic asthma. [9, 10]
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Lateral chest radiograph shows excessive tracheal narrowing.
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This shows the trachea during inspiration and expiration. Tracheal collapse of more than 50% during expiration is diagnostic of tracheomalacia.
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The mechanism of tracheal narrowing is shown here in healthy cases and in cases of tracheomalacia. Adapted from Feist JH, et al. Chest 68:3, Sept, 1975.
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Healthy trachea is visualized endoscopically.
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A 58-year-old woman with a history of polychondritis presented with inspiratory stridor and respiratory difficulties. The chest radiograph shows narrowing of the distal trachea on bronchoscopy. More than a 50% decrease in tracheal lumen occurred during expiration (see CT images).
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The CT scan of a 58-year-old woman with a history of polychondritis who presented with inspiratory stridor and respiratory difficulties shows tracheal narrowing of the distal trachea.
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CT image showing tracheal narrowing in a 58-year-old woman with a history of polychondritis who presented with inspiratory stridor and respiratory difficulties.
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A 3-dimensional reconstruction of CT scan images confirms the presence of tracheomalacia in a 58-year-old woman with a history of polychondritis who presented with inspiratory stridor and respiratory difficulties.
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Patterns of upper airway obstruction are presented here. Patient A has fixed upper airway obstruction. Patient B has variable extrathoracic obstruction, eg, vocal cord dysfunction. Patient C has variable intrathoracic obstruction, eg tracheomalacia.
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A flow volume loop shows a pattern of variable extrathoracic obstruction. Truncation of the expiratory limb is present. As the pleural pressure exceeds the airway pressure, airway collapse occurs due to flow limitation during expiration and not during inspiration.
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A flow volume loop shows the classic pattern of fixed upper airway obstruction. Truncation of both inspiratory and expiratory limbs is present.
