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Tracheal Diseases

Tracheal Diseases

1. Anatomy

A. The trachea
1) Average length is 11 cm (range 10-13 cm) and shortens with age
2) 18-22 rings (about 2 rings per cm)
3) The cricoid cartilage is the only complete ring
4) Average diameter is 2.3 cm laterally and 1.8 cm anteroposteriorly
5) In infants, the anterioposterior diameter is greater
6) COPD will increase the AP diameter ("saber sheath")
B. Anatomic relationships:
1) Anterior - thyroid isthmus, innominate artery, aortic arch
2) Posterior - esophagus
3) Lateral - azygous, pleura, recurrent laryngeal nerves
4) Inferior - anterior and posterior subcarinal lymph nodes
C. Arterial supply:
1) Three branches of the inferior thyroid artery on either side of the upper trachea
2) Subclavian, supreme intercostal, internal thoracic, innominate, superior and middle bronchial arteries all contribute to varying degrees
3) Lateral longitudinal vessel anastomoses feed transverse vessels, which penetrate between cartilage rings to supply submucosa
4) Mobilize only 1-2 cm circumferentially to avoid ischemic necrosis
5) Mobilize anteriorly and posteriorly to avoid significant vessels

2. Congenital Tracheal Anomalies

A. Agenesis or atresia
1) Usually fatal at birth
B. Tracheoesophageal fistula
1) Tracheal lesion easily closed, esophageal portion more difficult
2) Rarely has associated stenosis
C. Congenital stenosis
1) Webs and diaphragms most often occur at subcricoid level
2) Three types of stenosis: generalized hypoplasia, funnel-like narrowing, and segmental stenosis
3) Main bronchi most often normal with generalized hypoplasia, vary in size with funnel-like narrowing, and commonly have anomalies with segmental stenosis
4) Associated with a wide range of anomalies throughout the body
5) About 50% of pulmonary sling cases are associated with lower tracheal stenosis
D. Diagnosis of congenital stenosis
1) Suspicion in infants with inspiratory and expiratory stridor or more severe respiratory distress
2) Wheezing, retraction, poor feeding, failure to thrive may also be present
E. Management
1) Operations in infants are high risk, as postoperative edema may obstruct small airways and mechanical ventilation may disrupt anastomoses
2) A conservative approach is wise, as less than 1/3 of the trachea in a child can be resected
3) Webs can be dilated or excised endoscopically
4) Stenoses should not be dilated, as this can create longitudinal tears, resulting in recurrent scarring and stricture
5) Tracheostomy for palliation is a suitable alternative to allow growth for surgical repair

3. Tracheal Neoplasms

A. Primary neoplasms of the trachea are rare
B. Squamous cell carcinoma
1) Most common tracheal neoplasm
2) Well localized exophytic or ulcerated lesion
3) Multiple lesions or a superficially infiltrating variety also occur
4) 1/3 of patients will present with mediastinal or pulmonary metastasis
5) Spread is usually to regional tracheal lymph nodes and then directly into mediastinal structures
C. Adenoid cystic carcinoma (cylindroma)
1) Grows slowly and displaces mediastinal structures rather than invading
2) Submucosal and perineural spread may occur for quite long distances
3) Best chance at cure is complete resection at first operation
D. Clinical Features
1) Dyspnea on exertion
2) Wheezing
3) Stridor
4) Excessive secretions
5) Hemoptysis
6) Pneumonia
7) Cough
E. Secondary tracheal neoplasms
1) Thyroid cancers are the most common indication for tracheal operations for secondary malignancy
2) Laryngeal carcinoma involves the upper trachea by direct extension
3) Bronchogenic carcinoma more commonly involves the carina or bronchial origin on the right
4) Tracheoesophageal fistula can result from radiation therapy for or from invasion by esophageal cancer
5) Other tumor include carcinoid, head and neck, breast, and lymphoma

4. Infection and Inflammation

A. Tuberculosis may cause strictures of the lower trachea and bronchi
B. Strictures are submucosal and the cartilage has a grossly normal caliber
C. Fibrosing mediastinitis and histoplasmosis may be so extensive as to preclude reconstruction
D. Idiopathic strictures most often occur in the upper trachea
E. Other causes include Wegener's granulomatosis, amyloid, sarcoid, relapsing polychondritis, and tracheopathia osteoplastica

5. Trauma

A. Penetrating injuries
1) Usually involve the cervical trachea
2) Fresh injuries can be closed primarily
B. Blunt injuries
1) Closed trauma may lacerate or sever the trachea
2) A severed trachea should be re-approximated if possible
3) The distal trachea should be intubated for security
4) A tracheostomy tube should be inserted in the distal severed end for complex injuries and repair undertaken later
5) A vertical split at carina is usually diagnosed by a pneumothorax that fails to resolve with closed suction
6) Bronchoscopy, thoracotomy, and occasionally cardiopulmonary bypass are required to repair this lesion
7) Traumatic TEF should be promptly repaired, as inflammation makes repair difficult when the diagnosis is delayed
8) Always establish the function of the recurrent laryngeal nerves and larynx prior to surgery, if possible

6. Postintubation Injuries

A. These are currently the most frequent cause of tracheal stenosis
B. Laryngeal level
1) Sealing cuffs may irritate vocal cords, causing granulomas and fusion of the posterior commissure
2) Mucosal erosion at the cricoid can cause subglottic stenosis
3) Most lesions are reversible with time
C. Stomal level
1) Principle factors include a stoma that is too large, loss of tissue from infection (rare), and pressure erosion from rigid connecting systems (most common)
2) Avoid injuring the first cartilaginous ring during original tracheostomy to prevent subglottic stenosis
3) Avoid low placement of the tracheostomy to prevent innominate artery erosion and supracarinal stenosis
D. Sealing cuff level
1) Most common cause is direct pressure necrosis by high-pressure cuff
2) This has essentially disappeared with use of low-pressure, high-volume cuffs
3) Children may develop granuloma on anterior tracheal wall when ventilated without a cuff
E. Tracheomalacia
1) Usually occurs in segment of trachea between stoma and the cuff
2) Secretions pool here and inflammation leads to cartilage thinning
F. Tracheoesophageal fistula
1) Manifested by sudden appearance of secretions in tracheobronchial tree
2) Pneumonitis, pneumonia, abscess, and gastric dilitation may develop
3) Methylene blue in tube feedings will appear promptly in the trachea
G. Trachoinnominate fistula
1) Manifested by sudden exsanguinating hemorrhage into the tracheobronchial tree
2) Emergent tamponade with high-pressure cuff or digital pressure is necessary

7. Diagnosis

B. Fluoroscopy determines laryngeal function and presence of tracheomalacia
C. CT to evaluate extramural extension of tumors
D. Bronchoscopy and biopsy at the time of operation

8. Resection and Reconstruction

A. All patients should be induced slowly and gently in the OR
B. Extubation in the OR is desired in order to avoid intubation injury to the suture line
C. Upper half of trachea
1) Collar incision with partial upper sternal split, if necessary, is used for benign and malignant lesions of the upper trachea
2) Almost all stenoses above the carina can be reached through this approach as well
3) Dissect anteriorly from the cricoid cartilage to the carina, staying close to the trachea
4) The recurrent laryngeal nerves must be identified
5) Divide the trachea and intubate distally
6) About 4.5 cm can be removed without additional mobilization
7) Laryngeal release is preferred, if needed, taking care to avoid injury to the superior laryngeal nerves
8) Hilar release is more hazardous and is contraindicated in patients with poor pulmonary function
9) Once the sutures have been placed, the distal tube is removed and the endotracheal tube is readvanced past the anastomosis
10) All sutures are tied and the anastomosis tested under water for leakage
B. Lower half of trachea
1) Posterolateral thoracotomy in 4th interspace provides optimal exposure and should be performed on the side contralateral to the aortic arch (usually right)
2) About 4.5 to 5 cm can be resected without extreme maneuvers
3) Release technique include hilar dissection, loosening of the carina, and cervical flexion
4) Laryngeal release does not provide any additional mobilization
5) A pleural or pericardial flap is constructed to protect the anastomosis

9. Tracheostomy

A. Principal indications include upper airway obstruction, management of secretions, prolonged ventilation, and emergent airway
B. Second and third rings are opened vertically
C. Avoid high and low stoma placement to prevent subglottic stenosis and innominate artery erosion
D. Persistent stoma 3 to 6 months after tracheostomy should be closed surgically

10. Results

A. Small numbers of patients make accurate predictions of survival difficult
B. Resection of benign tumors and low-grade malignant tumors appears to have high probablity of cure
C. Single-stage resection and reconstruction is probably the best approach for squamous cell and adenoid cystic carcinoma
D. Adjunctive radiation is usually indicated for squamous cell and adenoid cystic tumors
E. Selected patients can be treated effectively with resection and reconstruction for secondary tracheal tumors