Compression of the trachea by vascular structures or masses can cause significant respiratory compromise. Tracheal compression by aberrant great vessels (aorta, innominate artery) may cause wheezing, stridor, cough, and dyspnea. The most common cause of tracheal compression is anterior compression from an anomalous innominate artery that arises more distally than normal from the aortic arch. This usually results in mild respiratory symptoms, and surgical correction is rarely necessary. Complete vascular rings, which compress the esophagus posteriorly and the trachea anteriorly, include the double aortic arch and a right aortic arch with a persistent ligamentum arteriosum (most common). Both lesions have right-sided aortic arches, which may be visible on chest radio-graph. In addition to respiratory symptoms, complete vascular rings may cause dysphagia as a result of esophageal compression. The diagnosis of vascular anomalies can often be made by a barium swallow, which identifies the esophageal compression. Bronchoscopy will identify a pulsatile compression of the airway, but the diagnostic procedure of choice is a computed tomography (CT) angiogram of the chest and great vessels. Complete vascular rings almost always require surgical repair. Other causes of extrinsic tracheal compression include enlarged mediastinal lymph nodes (tuberculosis), mediastinal masses (teratoma, lymphoma, thymoma, germ cell tumors), and, rarely, cystic hygromas.
Aspiration of foreign bodies into the trachea and bronchi is relatively common. The majority of children who aspirate foreign bodies are under 4 years of age. Most deaths secondary to foreign body aspiration occur in this age group. Because the right mainstem bronchus takes off at a less acute angle than the left mainstem bronchus, foreign bodies tend to lodge in right-sided airways. Some foreign bodies, especially nuts, can
Chapter 136 u Lower Airway, Parenchymal, and Pulmonary Vascular Diseases 471 also lodge more proximally in the larynx or subglottic space, totally occluding the airway. Many foreign bodies are not radiopaque, which makes them difficult to detect radiographically. The most common foreign bodies aspirated by young children are food (especially nuts) and small toys. Coins more often lodge in the esophagus than in the airways. Older children have been known to aspirate rubber balloons, which can be life-threatening.
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Many children who aspirate foreign bodies have clear histories of choking, witnessed aspiration, or physical or radiographic evidence of foreign body aspiration. However, a small percentage of patients have a negative history because the aspiration went unrecognized. Physical findings observed with acute foreign body aspiration may include cough, localized wheezing, unilateral absence of breath sounds, stridor, and, rarely, bloody sputum.
Most foreign bodies are small and quickly expelled, butsome may remain in the lung for long periods of time andmay come to medical attention because of persistent cough,sputum production, or recurrent unilateral pneumonia. Foreign body aspiration should be in the differential diagnosis ofpatients with persistent wheezing unresponsive to bronchodilator therapy, persistent atelectasis, recurrent or persistentpneumonia, or chronic cough without another explanation.Foreign bodies may also lodge in the esophagus and compress the trachea, thus producing respiratory symptoms.Therefore, esophageal foreign bodies should be included inthe differential diagnosis of infants or young children withpersistent stridor or wheezing, particularly if dysphagia is present.