The upper airways may become involved in a variety of disease processes, often secondary to a more systemic illness. Relapsing polychondritis is a disease of unknown origin in which any cartilaginous structure in the body may be affected, most commonly the nose and ears. When the upper airways are involved, patients experience progressive airway obstruction and difficulty in clearing secretions. The disease has a variable course, and therapy is usually limited to palliative stenting.
Wegener's granulomatosis is a systemic inflammatory disease that may involve the upper airways and lead to obstruction. Treatment is focused primarily on the systemic disease. Similarly, amyloidosis at times may affect the upper airways, leading to obstruction. Sarcoidosis may affect the upper airways by causing extrinsic compression from enlarged mediastinal lymph nodes or by causing extensive fibrotic changes within the airway, leading to stenosis and obstruction. Treatment is focused on the underlying condition because the airway process is usually too extensive and diffuse to permit surgical resection. Tracheopathia osteoplastica is a variant condition characterized by the formation of calcified nodules beneath the mucosa adjacent to but not involving the cartilages. It has a variable course and rarely requires surgical treatment.
Tuberculosis may involve the upper airways. Acutely, patients may be affected by tracheitis; as this process heals after medical treatment, a stenosis may develop. On rare occasions, segmental resection may become necessary. However, this should be performed only long after the active process is controlled. Histoplasmosis also may affect the upper airways, principally by causing extrinsic compression. The dense mediastinal fibrosis, as well as the enlarged and hardened mediastinal lymph nodes, may lead to compression of the distal trachea, carina, and mainstem bronchi. In addition, broncholiths may be seen within the airway as a result of erosion of a lymph node. Involvement of the upper airways by cicatricial pemphigoid also has been reported.
A number of congenital vascular anomalies may lead to extrinsic compression of the upper airways. These anomalies typically present in infants or young children and nearly always require surgical correction because of airway obstruction (see Chapter 39). A double aortic arch is the most common complete vascular ring that causes tracheal compression. Anatomically, this anomaly is characterized by an ascending aorta that divides into two arches. The two arches pass around the esophagus and trachea and then rejoin posteriorly to form the descending aorta. Usually, one of the arches is dominant, most commonly the right one. Affected patients typically present in the first year of life with stridor, respiratory distress, and a characteristic seal bark cough. The diagnosis is made by barium esophagram in the appropriate clinical setting. In addition, a CT scan or MRI may be obtained. The treatment is surgical division of the nondominant portion of the double arch at its insertion into the descending aorta, thereby releasing the complete ring. The ligamentum arteriosum, as well as any adhesions around the trachea and esophagus, is also divided. The results of surgery are excellent, with complete resolution of both respiratory and esophageal symptoms.
A right aortic arch with a left ligamentum arteriosum also may form a complete ring and lead to compression of the airway and esophagus. In this anomaly, which may have several variations, the compression is not as severe as with double aortic arch; this may lead to a later onset of symptoms and therefore presentation. The diagnosis is established in a similar manner to double arch. Treatment is also surgical, with division of the ligamentum and release of the ring. Results are excellent, and nearly all patients are relieved of their symptoms one year after treatment.
Rarely, the innominate artery may cause anterior compression of the trachea. This anomaly is seen when the innominate appears to originate from a more posterior location on a normally located aortic arch. The diagnosis is usually suspected on CT scan and can be confirmed by rigid bronchoscopy. Surgical treatment, when indicated, attempts to achieve relief of the anterior compression by suspending the innominate artery to the posterior aspect of the sternum.
A pulmonary artery sling is characterized by a left pulmonary artery that originates from the right pulmonary artery. As the anomalous pulmonary artery courses anteriorly to the esophagus to the hilum of the left lung, a ring is formed that encircles the right mainstem bronchus and distal trachea. In addition to the extrinsic compression, approximately 50% of patients with this anomaly will have complete tracheal rings, leading to severe airway stenosis. Nearly all patients with pulmonary artery sling present in early infancy with respiratory distress, which may be particularly severe if complete tracheal rings are also present. The diagnosis is suspected by the observation of hyperaeration of the right lung on plain chest radiograph as well as with anterior compression of the esophagus on barium esophagram (all other lesions show posterior compression). Both CT scan and MRI may confirm the diagnosis. However, echocardiography is the current modality of choice for making the diagnosis. Echocardiography has been shown to be very accurate and obviates the need for any sedation in an infant whose respiratory status may be tenuous at best. Treatment is always surgical. Although several approaches have been described, surgical correction is usually achieved using cardiopulmonary bypass.12 The left pulmonary artery is divided and reimplanted into the main pulmonary artery anterior to the trachea. In the presence of complete tracheal rings, a simultaneous tracheoplasty may be performed.
Congenital Tracheal Stenosis
Congenital tracheal stenosis is a rare but life-threatening disorder characterized by congenital absence of the membranous trachea. The trachea is composed of complete cartilaginous O rings, and although the length may vary, this most frequently leads to long-segment tracheal stenosis. The type of stenosis is classified into three categories and may involve the mainstem bronchi as well. In one report, the medical management of this entity resulted in a greater than 40% mortality.13
The diagnosis is suspected on clinical grounds. These patients present in the first months of life with severe respiratory distress. The diagnosis is confirmed and the extent of airway involved is assessed by rigid bronchoscopy. Since these patients frequently have other malformations, such as pulmonary artery sling and/or cardiac abnormalities, it is important to perform a thorough diagnostic evaluation before undertaking any surgical repair of the airway.
As alluded to earlier, treatment is surgical correction. For short-segment stenosis, segmental resection and reconstruction are sufficient to achieve long-term patency of the airway. Wright et al.14 have reported that resection of more than 30% of the pediatric airway results in a substantial failure rate. For long-segment stenosis, a number of surgical options have been devised, including pericardial patch tracheoplasty and slide tracheoplasty. Surgical correction of the stenosis may be made more difficult by the need to correct other anomalies in the same setting (e.g., pulmonary artery sling).
Large goiters, particularly those with a significant posterior component, may compress the airway. The goiter may alter the shape of the airway over a prolonged period of time, leading to some compromise in the lumen of the airway. In rare instances, the compression may lead to softening of the tracheal cartilages, resulting in a malacic airway. The diagnosis of compression is made by bronchoscopy. Surgical resection of the compressing goiter results in significant improvement in respiratory symptoms. However, if malacia has occurred, care must be exercised, for removal of the goiter actually may remove an element of support for the airway and therefore lead to airway collapse.
This rare entity occurs most commonly after right pneumonectomy. The mediastinum shifts to the right and may lead to angulation and compression of the remaining airway. Typically, the carina and left mainstem bronchus are compressed by the left pulmonary artery anteriorly and the aorta or vertebral column posteriorly. The syndrome also may occur in a reverse manner in the presence of a right aortic arch. The diagnosis is made by cross-sectional imaging and bronchoscopy in the appropriate clinical setting. Surgical treatment involves mediastinal repositioning, as reported by Grillo et al.15
The upper airways, like any other organ in the body, may be involved by penetrating trauma. Gunshot wounds to the neck that involve the airway are often fatal. When not fatal, the airway injury is usually a laceration. Penetrating knife wounds to the neck area may cause tracheal laceration. Diagnosis is made on clinical grounds. Respiratory distress, subcutaneous emphysema, and the presence of a neck wound should strongly raise the suspicion of an airway injury. In the chest, the presence of a pneumothorax with a transmediastinal missile also should raise suspicion of airway injury. After ensuring a secure airway, bronchoscopy is mandatory for evaluation. Depending on the degree of associated injuries, the airway laceration simply may be repaired primarily with absorbable suture; the repair should be buttressed with viable tissue. In rare circumstances, segmental resection and reconstruction may be required.
Blunt trauma also may cause significant damage to the upper airways. At times, this damage may go undetected for prolonged periods of time. Ruptures of the airways may not be recognized at the time of initial presentation and may be detected only when the airway has become stenotic with time. The stenoses usually are severe and may compromise the distal airways. The diagnosis is made by bronchoscopy in the appropriate clinical setting, and the treatment is resection of the stenosis with reconstruction as soon as possible.
Total tracheal disruption is an often fatal injury. However, some patients survive and are treated with emergent tracheostomy. The recurrent laryngeal nerves are usually damaged, sometimes permanently. With time, the area of separation becomes severely stenotic. Although difficult, reconstitution of a suitable airway may be accomplished.
The upper airways may incur damage as a result of attempted therapeutic interventions. Segmental resection and reconstruction may result in anastomotic stricture, particularly if the blood supply has been damaged. Radiation therapy may result in inflammation, fibrosis, and ultimate stenosis of the airway. Laser and burn injuries to the airways also may lead to fibrosis and stenosis. The placement of stents, particularly self-expanding metal stents, may result in strictures and granulations of the airway.
The airway may be damaged as a result of intubation. The damage may be caused by standard nasal or oral endotracheal tubes or from tracheostomy tubes. Although a number of lesions may be seen, the most common are those that lead to airway obstruction. Stenosis occurs at the site of the cuff and may be seen as a result of a period of intubation as short as 2 days. The damage and resulting stenosis occur as a result of pressure necrosis on the tracheal wall by an overinflated cuff. In patients who have undergone tracheostomy, granulations may occur at the tracheostomy site as well, also leading to obstruction. Symptoms may occur as early as 2 days after extubation but may occur up to several months after extubation. The diagnosis requires a high index of suspicion in these patients, often for prolonged periods of time, owing to a delay in diagnosis. Every patient who develops symptoms of airway obstruction and who has a history of being intubated for over 24 hours or more within the previous 2 years must be suspected of having an airway stenosis.16 Although treatment must be individualized, these lesions are often amenable to successful segmental resection and reconstruction.