The upper airways are defined as the trachea and mainstem bronchi. Functionally, the upper airways serve as conduits for ventilation. Anatomically and physiologically, however, they represent complex structures that are susceptible to a wide variety of processes. Involvement of the trachea, mainstem bronchi, or both in various disease processes, although rare, present challenging problems for both physician and patient.

The adult human trachea begins at the level of the cricoid cartilage and extends to the bifurcation of the mainstem bronchi (Figs. 53-1 and 53-2). The carinal spur is a useful landmark that denotes the distal extent of the trachea. On average, the adult human trachea measures 11 cm in length, with some variation in proportion to the height of the individual patient. There are approximately two tracheal rings per centimeter of trachea. Thus, on average, the total number of tracheal rings ranges from 18 to 22, with the cricoid forming the only complete tracheal ring. The potential for presentation of the trachea in the neck is a major factor permitting relatively easy surgical access. In a young, nonobese adult, hyperextension of the neck may deliver more than 50% of the trachea into the neck, thereby greatly facilitating any attempt at resection and reconstruction. From a nearly subcutaneous position at the level of the cricoid, the trachea courses posteriorly and caudally at an angle, resting against the esophagus and vertebral column at the level of the carina.

The blood supply of the trachea is vital to successful resection and reconstruction. The upper trachea is principally supplied by branches of the inferior thyroid artery, whereas the lower trachea is supplied by branches of the bronchial artery as well as by branches of the subclavian, supreme intercostals, internal thoracic, and innominate arteries (Fig. 53-3)¹. These vessels supply the trachea through lateral pedicles of tissue, and the longitudinal anastomoses between the vessels are very thin. Excessive disruption of these lateral vessels by circumferential dissection of the trachea may compromise blood supply and lead to complications, such as stenosis and anastomotic dehiscence. At the level of the second and third tracheal rings, the thyroid isthmus crosses the trachea anteriorly. The recurrent laryngeal nerves course in a groove between the trachea and the esophagus (Fig. 53-4). The nerves enter the larynx between the cricoid and thyroid cartilages.

The trachea bifurcates into the right and left mainstem bronchi in the region of the fifth through seventh thoracic vertebra. The right mainstem bronchus arises in a direct line with the trachea, whereas the left mainstem bronchus arises at a sharper angle. This anatomy helps to explain the more frequent right-sided location of aspirated material(s).

The length of the right mainstem bronchus from the trachea to the point of the takeoff of the right upper lobe bronchus is approximately 1.2 cm. The length of the left mainstem bronchus is approximately 4 to 6 cm from the trachea to the takeoff of the left upper lobe bronchus. Both mainstem bronchi are supplied directly by bronchial arteries.

Most commonly, the trachea is approached through a cervical neck incision. As noted earlier, up to 50% of the entire trachea may be accessed in this manner. The right and left mainstem bronchi are usually approached through a right posterolateral thoracotomy. The carina may be approached through a right posterolateral thoracotomy, a clam shell incision, or a median sternotomy.

Diseases affecting the upper airways are rare. Tumors of the trachea and mainstem bronchi occur most commonly in adults. Most of the primary tumors are malignant, with the majority representing adenoid cystic carcinoma or squamous cell carcinoma. Benign tumors occur most commonly before the seventh decade of life. They tend to occur sporadically and lead to symptoms secondary to progressive airway obstruction. Nonneoplastic diseases, such as infection, are less common than tumors, although the precise incidence is difficult to discern. Left untreated, diseases affecting the upper airways cause significant morbidity and, in some cases, mortality from airway obstruction.

Symptoms of upper airway pathology are often subtle and insidious in onset. The rarity of upper airway diseases may delay the suspicion of airway pathology as the cause of an individual patient’s symptoms. Shortness of breath is the most common symptom experienced by patients who are affected by disease of the upper airways.² When a tumor or mass is present, dyspnea occurs after the effective airway lumen has been narrowed by approximately one-third. Even in the face of significant airway narrowing, the patient will have an apparently normal chest x-ray and often is diagnosed as suffering from “asthma.” At times, these patients are treated with steroids for prolonged periods of time before a specific diagnosis, such as a tracheal tumor, is established. As the airway narrows further, the classic symptom of wheezing becomes more prominent. The presence of stridor indicates severe compromise of the airway. Failure to improve on steroid therapy often leads to further workup, at which time a specific upper airway diagnosis is established. Cough is another common symptom and may be secondary to irritation or to ineffective clearance of secretions, leading to pneumonia.

The symptoms caused by diseases of the upper airways are common to many processes. Other causes of dyspnea must be considered. These include cardiac causes, such as congestive heart failure, as well as pulmonary causes, such as pulmonary embolus. In addition, a myriad of other common processes, such as chronic obstructive pulmonary disease, must be considered. Wheezing is most commonly a sign of primary reactive airways disease, whereas cough may be caused by pneumonia as well as other processes that irritate the airways. It is important to remember, however, that it is the potentially numerous and far more common processes that produce symptoms similar to those of upper airway diseases that often lead to the delay in diagnosis of upper airways disease.

The overpenetrated posteroanterior chest x-ray is often the most useful means by which to obtain an excellent view of the trachea and mainstem bronchi. The presence of a mass and extent of luminal narrowing may be seen by careful inspection of the tracheal air column. Deviation from midline of the tracheal air column also may be noted on a standard chest film. Furthermore, postobstructive pneumonia may be seen. Although not universally available, tracheal tomograms, as described by Weber and Grillo,³ provide excellent visualization of the entire upper airways. These are particularly useful in planning for resection and reconstruction. These are no longer necessary in the era of CT scans and three-dimensional (3D) reconstruction.

CT scanning permits cross-sectional visualization of the upper airways. The presence of an intraluminal mass is often clearly identified by CT scan. Furthermore, by knowing the distance between cuts, or utilizing spiral CTs, one often can accurately estimate the size of the mass as well as the length of airway involved. 3D helical CT scanning and reconstructed axial imaging are used to obtain virtual bronchoscopic views of the upper airways, thereby permitting an accurate assessment of airway pathology. The presence of an extrinsic mass that is compressing the airways is also best identified by CT scan. MRI may supply additional information, but it is rarely more helpful than the information obtained by CT scan.

On occasion, especially in cases of extrinsic compression of the airway, a barium esophagram may be useful. Rarely, arteriography may be useful in defining compression of the airway by vascular structures.

Functional studies may provide useful information in the diagnosis of upper airway disease. Pulmonary function studies may point to airway obstruction. A decrease in peak flow rates, as well as a flattening of the expiratory flow-volume loop, may lead to suspicion of an obstructive process if clinical signs have been overlooked. Furthermore, pulmonary function studies may provide information regarding the status of the pulmonary parenchyma. While this may not alter the decision to perform surgery, it may alter the conduct of a given operation, for example, whether or not single-lung ventilation will be tolerated.

Bronchoscopy is mandatory in the evaluation of upper airway disease. If a mass is noted in the airway, bronchoscopy is essential to establishing a histologic diagnosis (i.e., biopsy) and for determining the extent of the mass. If it is necessary to establish an adequate airway by removing a portion of a tumor or to obtain more adequate tissue for diagnosis, then rigid bronchoscopy may be preferable. Bronchoscopy always should be performed by experienced individuals and with appropriate precautions for the possibility of airway compromise. When the indications for surgical resection and reconstruction have been established by other modalities, bronchoscopy may be deferred until the time of the operative procedure.

Tumors

Chondroma

Chondroma is the most common benign mesenchymal tumor of the upper airways.⁴ Histologically, chondromas resemble normal cartilage and can exhibit vascular invasion. Approximately 200 cases have been reported in the world literature. And there is a 5:1 male predominance. Most patients present in adulthood.

Grossly, the tumor appears as a firm, white nodule that projects into the lumen of the airway (Fig. 53-5). The most common site of origin is the internal aspect of the posterior cricoid lamina. These tumors are covered by a normal mucosa, and calcification is present in up to 75% of the patients. The firm consistency of the tumor may make it difficult to obtain a biopsy. No clear etiology for these tumors has been described. Although these tumors can be removed bronchoscopically, local recurrence has been observed. There also have been reports of malignant transformation. For these reasons, the recommended treatment is segmental resection with a rim of normal tissue.⁵