Introduction
Background
The causes of adult laryngeal and upper tracheal stenosis are trauma, chronic inflammatory diseases (eg, amyloidosis, sarcoidosis, relapsing polychondritis), benign neoplasm (eg, respiratory papillomatosis), malignant neoplasm (eg, primary tracheal, secondary invasion, metastatic), and collagen vascular diseases (eg, tracheopathia osteoplastica, Wegener granulomatosis). The most common cause of laryngotracheal stenosis continues to be trauma, which can be internal (eg, resulting from prolonged endotracheal intubation, tracheotomy, surgery, irradiation, endotracheal burns) or external (eg, blunt or penetrating neck trauma). Of these causes, it has been the authors' experiences that prolonged endotracheal intubation is the leading cause of laryngotracheal stenosis, and this condition occurs mainly in patients with multiple trauma or in those who have undergone cardiovascular surgery.
In 1880, William MacEwen first reported endotracheal intubation for anesthesia,1 and in 1969, Lindholm reported injuries to the larynx and trachea after intubation for this purpose.2 The current use of high-volume, low-pressure cuffs has almost eliminated the tracheal lesions that are caused by pressure from the cuff of the endotracheal tube. However, the number of intensive care patients who require intubation and artificial ventilation has increased dramatically.
Pathophysiology
The sequence of events that leads to laryngeal and upper tracheal stenosis in adults involves ulceration of the mucosa and cartilage, inflammatory reactions with associated granulation tissue, fibrous tissue formation, and contraction of fibrous scar tissue. Capillary perfusion pressure is a crucial consideration in mucosal injury, and mucosal ischemia is produced by direct contact with an endotracheal tube segment or by an increase in the pressure in the tube cuff.
Ulceration is the earliest laryngotracheal injury that is produced by an endotracheal tube. Ulcer healing involves regeneration of the epithelium (primary healing) or repair (secondary healing). If the regenerated epithelium fails to cover the granulation tissue (ie, pseudopapillary or nodular granulation tissue), the growth of the granulation tissue becomes exaggerated. After weeks or months, the once-vascular tissue becomes an almost avascular scar that contains only a few widely separated blood vessels.
Freitag and colleagues have recently proposed a new classification method that is based on a detailed description of the type, location, and degree of the airway stenoses.3
The type of stenoses includes 2 groups as follows:
- Structural stenosis
- Stenosis due to all types of exophytic intraluminal malignant or benign tumors and granulation tissue
- Extrinsic compression
- Narrowing due to airway distortion, kinking, bending, or buckling
- Shrinking or scarring (eg, postintubation stenosis)
- Dynamic (functional) stenosis
- Triangular- or tent-shaped airway, in which cartilage is damaged
- Inward bulging of the floppy posterior membrane
The degree of the stenosis is assigned by a numerical code:
Open table in new window
0 | None |
1 | <25% |
2 | 26–50% |
3 | 51-75% |
4 | 76-90% |
5 | 90-100% |
The location of the stenosis is divided into 5 regions:
- Upper one third of the trachea
- Middle one third of the trachea
- Lower one third of the trachea
- Right main bronchus
- Left main bronchus
Frequency
United States
Tracheal stenosis affects 4-13% of adults and occurs in 1-8% of neonates who have had prolonged intubation. Primary tracheal tumors are rare causes of tracheal stenosis.
Recurrent respiratory papillomatosis most commonly involves the larynx, but other areas of the respiratory tract may be affected. Some authors consider these papillomas the most common benign laryngeal tumors. Tracheobronchial involvement is usually secondary to contamination following tracheotomy.
Sarcoidosis involves the larynx in 5% of affected patients and the trachea in 1% of cases; however, this disease remains a diagnosis of exclusion. Laryngeal or tracheal involvement occurs in 50-70% of patients who have relapsing polychondritis. In cases of Wegener granulomatosis, tracheobronchial involvement occurs in 10-20% of the affected patients.
Mortality/Morbidity
Severe congenital laryngotracheal or benign acquired stenosis requires immediate airway intervention, but less than one half of the patients who have the congenital condition require tracheotomy. Individuals may seek medical care only after they have had repeated episodes of laryngotracheal infections or exercise intolerance.
Race
The authors are not aware of any racial prevalence.
Sex
To the authors' knowledge, males and females are equally affected.
Age
Postintubation tracheal stenosis is uncommon in children. Congenital stenosis is even more uncommon.
Anatomy
Gross anatomy and vascular supply
The trachea occupies the anterior and middle portions of the neck and penetrates into the superior mediastinum behind the sternum. The airway begins at the level of the cricoid cartilage and ends at the level of the sternal angle, where it bifurcates to form the 2 main stem or primary bronchi. The trachea takes the shape of a cylindrical tube, with a flattened posterior wall, wherein its skeletal structure is composed of C-shaped hyaline cartilage (tracheal rings). None of the tracheal rings are complete; they all have a posterior opening that is filled with fibroareolar connective tissue and transversely oriented smooth muscle fibers.
The trachea has 2 depressions — a superior depression that is formed by the left thyroid lobule and an inferior depression near the bifurcation made by the aorta — and its lumen is lined by mucosa that consists of a thin lamina propria and a ciliated, pseudostratified columnar epithelium. In men, the trachea is about 12 cm long and has a transverse anteroposterior (AP) diameter of 20 mm; in women, the tracheal length is approximately 11 cm, with a transverse AP diameter of 10 mm.
The superior and inferior thyroid, thymic, and right bronchial arteries provide the trachea's arterial supply. The venous blood vessels form rings that travel along the intercartilaginous spaces and flow into the esophageal and inferior thyroid veins. Tracheal innervation is provided by the vagus nerve (pulmonary plexus and laryngeal nerves) and the sympathetic nerves (cervical and dorsal ganglia).
Surgical anatomy
The indications for tracheal reconstructive operations are primary tumors, secondary tumors (thyroid, bronchogenic, esophageal), postintubation lesions, and other causes of stenoses.
The anterior surgical approach to the trachea is used for most benign lesions. It is very important to limit dissection to the anterior face of the trachea to prevent injuring the recurrent laryngeal nerves and venous plexus, which are located lateral to the trachea. The anastomosis must be made without tension.
Presentation
Acquired benign stenoses may cause symptoms a few days to weeks after extubation. Frequently, symptoms develop after a latency period of months to years.
Symptoms of dyspnea may vary from a discrete wheezing to severe asphyxia. Stridor occurs during inspiration and expiration.
Preferred Examination
A thorough patient history should be obtained, with a complete medical history that is directed toward any previous airway intervention (intubation or tracheotomy) and head and neck, thoracic, or trauma surgery. Upper airway dysfunction in acute fulminant processes may be obvious on simple examination of the patient, but chronic subtle cases are more difficult to diagnose.
Complete evaluation of the airway requires a thorough knowledge of its anatomy and physiology. The larynx, hypopharynx, and proximal trachea are assessed with an indirect mirror examination, a 70° or 90° telescope, or a flexible, fiberoptic nasolaryngoscope.
Bronchoscopy is considered the gold standard for the detection and diagnosis of tracheobronchial pathology because it permits direct visualization of the airway lumen. However, bronchoscopy has potentially hazardous complications such as profound oxygen desaturation in hypoxemic patients, tachycardia, cardiac arrhythmias, and endoscopy-induced inflammation.
Laboratory evaluation in patients with tracheal stenosis can demonstrate changes in serum electrolyte levels, acid-base balance, blood-oxygen level, and red blood cell count.
Plain AP and lateral radiographic images of the upper airway are obtained with a soft-tissue protocol during both inspiration and expiration. These studies may be used to diagnose the cause of tracheal obstruction. AP and lateral chest radiographs are also useful. In addition, high-resolution computed tomography (CT) scanning of the neck and thorax may be performed, and lung function may be analyzed.
Limitations of Techniques
The endoscopic evaluation can be subjective and dependent on the endoscopist's skills. Other technical limitations include the inability to evaluate the airway caliber and morphology beyond a high-grade stenosis of the bronchial lumen, difficulty passing the endoscope through severely narrowed airway sections, the scarce information that may be obtained about the extent of any extraluminal disease, and patient intolerance of the procedure.
Few contraindications exist for endoscopic examination, but cervical spine disorders and coagulopathy are among them. Patients who have significant airway compromise should not undergo flexible endoscopy unless rigid endoscopic equipment and an experienced team are readily available to establish an adequate airway in emergent situations. Rigid laryngotracheobronchoscopy is useful for the diagnosis and therapy of tracheal stenosis, but this procedure should be performed with general anesthesia. Flexible endoscopy is better for diagnosis and can be performed with local anesthesia.
Differential Diagnoses
Airway Foreign Body
Asthma
Epiglottitis, Acute
Other Problems to Be Considered
Patients who need prolonged endotracheal intubation and who present with a feeding problem have almost always been placed under a nothing-by-mouth (NPO) status and receive a nasogastric or nasojejunal tube. Either tube can add to tracheal damage by causing internal trauma to the esophagus, which can lead to the formation of a fistula between the 2 structures. This fistula must be identified with endoscopy, dynamic radiographic imaging studies performed with a small volume of barium or water-soluble contrast agent, or CT scanning.
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Further Reading
Keywords
upper airway stenosis, stenotic trachea, tracheal trauma, laryngotracheal stenosis, narrow airway
