|Year : 2017 | Volume
| Issue : 1 | Page : 60-61
Sibes K Das MD (Pulmonary Medicine) 1, Anirban Das2, Soumya Sarkar1, Himadri Samanta1
1 Department of Pulmonary Medicine, Medical College, Kolkata, India
2 Department of Pulmonary Medicine, Murshidabad Medical College, Murshidabad, West Bengal, India
|Date of Web Publication||29-Dec-2016|
Sibes K Das
Department of Pulmonary Medicine, Medical College, Kolkata
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Das SK, Das A, Sarkar S, Samanta H. Saber-sheath trachea. J Assoc Chest Physicians 2017;5:60-1
A 55-year-old man, a known case of chronic obstructive pulmonary disease (COPD), was admitted with nonsevere exacerbation. He was treated with controlled oxygen, intravenous coamoxyclav, nebulization with salbutamol, and oral prednisolone. His chest radiograph showed evidence of hyperinflation along with intrathoracic narrowing of trachea [Figure 1]. High-resolution computed tomography (HRCT) scan of thorax showed presence of multiple bullae, evidence of emphysema, and reduction of coronal diameter and increase of sagittal diameter of intrathoracic trachea suggestive of saber-sheath trachea [Figure 2].
|Figure 1: Chest X-ray PA view showing narrowing of intrathoracic trachea along with evidence of hyperinflation|
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|Figure 2: HRCT scan of thorax showing saber-sheath trachea along with multiple bullae and emphysema|
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Saber-sheath trachea is a fixed deformity of the intrathoracic trachea, which is characterized by reduction in coronal diameter associated with an increase in sagittal diameter, as conventionally measured 1 cm above the aortic arch. The extrathoracic trachea is normal. It is considered to be present when tracheal index, i.e., ratio of coronal to sagittal diameter is <0.50. It is considered as diagnostic of COPD. The sensitivity of this sign is above 90% but the specificity is below 40%. It is thought to be because of increased intrathoracic pressure as a result of hyperinflation, chronic injury, and softening of tracheal cartilage secondary to chronic cough. Saber-sheath trachea is generally evident after the age of 50 years. It is unlikely to contribute significantly to airflow obstruction. Saber-sheath trachea may provide a clue to the presence of COPD when other radiological signs are absent. In computed tomography (CT), there is inward displacement of the lateral portions of the tracheal wall and tracheal cartilage with side-to-side narrowing of the tracheal lumen. The tracheal wall usually is of normal thickness. During forced expiration, CT demonstrates further inward bowing of the tracheal walls in many patients.
Saber-sheath trachea is correlated with functional severity, being more common in global initiative for chronic obstructive lung disease (GOLD) stages III and IV. Chest radiography is considered as good as CT scan in detecting this deformity. Saber-sheath trachea is considered a fixed tracheal deformity, as the tracheal index does not change over time.
As chest radiograph is routinely performed in the evaluation of patients with COPD, we recommend performing a careful assessment of intrathoracic trachea, which can provide the physician with important clues to the presence of COPD, specially in the presence of otherwise negative or nonspecific radiological findings.
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[Figure 1], [Figure 2]