Imaging Studies
Chest radiography
Chest radiography may demonstrate hyperinflation, excessive narrowing of the tracheal lumen during expiration, or vascular anomalies such as double aortic arch; further evaluation usually is required. (See the images below.)
This shows the trachea during inspiration and expiration. Tracheal collapse of more than 50% during expiration is diagnostic of tracheomalacia.
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).
Cinefluoroscopy
Cinefluoroscopy performed with contrast in the esophagus utilizing quiet respiration and coughing has proved to be an optimal means of establishing a diagnosis. During coughing, more than half to complete collapse of tracheal lumen confirms the diagnosis. In addition to showing collapse of the tracheal wall, cinefluoroscopy may identify esophageal defects, and it may reveal deformation of tracheal contour due to vascular anomaly.
Computed tomography
The dynamic airway collapse is better appreciated with ultrafast computed tomography (CT). Dynamic expiratory CT elicits a larger degree of airway collapse than standard end-expiratory CT in patients with tracheobronchomalacia. [11] Fourteen patients (11 men, 3 women; age range, 19-79 years) were included in a study to assess airway collapse for confirmation of a diagnosis of tracheobronchomalacia; dynamic expiratory CT revealed a significantly greater degree of airway collapse than end-expiratory CT. [12] (See the images below.)
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.
CT image showing tracheal narrowing in a 58-year-old woman with a history of polychondritis who presented with inspiratory stridor and respiratory difficulties.
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.
Endoscopy
The definitive diagnosis of major airway depends on obtaining an accurate history combined with proper endoscopic evaluation (see the image below). [11] The airway is directly visualized during spontaneous respiration using ventilating laryngoscope and telescoping bronchoscopy. Flexible bronchoscopy also may be utilized. The findings consist of the following classic triad:
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Loss of normal semicircular shape of tracheal lumen
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Forward ballooning of the posterior membranous wall
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Anteroposterior narrowing of the tracheal lumen
Other Tests
In pulmonary function testing, the flow-volume curve, though usually performed in adults rather than children, may demonstrate a normal inspiratory curve but a truncated expiratory limb.
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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.
