Tracheal disease

# Normal Anatomy of Trachea

## A. The trachea
- Average length is 11 cm (range 10-13 cm) and shortens with age
- 18-22 rings (about 2 rings per cm)
- The cricoid cartilage is the only complete ring
- Average diameter is 2.3 cm laterally and 1.8 cm anteroposteriorly
- In infants, the anterioposterior diameter is greater
- COPD will increase the AP diameter ("saber sheath")

## B. Anatomic relationships:
- Anterior - thyroid isthmus, innominate artery, aortic arch
- Posterior - esophagus
- Lateral - azygos, pleura, recurrent laryngeal nerves
- Inferior - anterior and posterior subcarinal lymph nodes

## C. Arterial supply
- Three branches of the inferior thyroid artery on either side of the upper trachea
- Subclavian, supreme intercostal, internal thoracic, innominate, superior and middle bronchial arteries all contribute to varying degrees
- Lateral longitudinal vessel anastomoses feed transverse vessels, which penetrate between cartilage rings to supply submucosa
- Mobilize only 1-2 cm circumferentially to avoid ischemic necrosis
- Mobilize anteriorly and posteriorly to avoid significant vessels

# Congenital Tracheal Anomalies

## A. Agenesis or atresia
- Usually fatal at birth

## B. Tracheoesophageal fistula
- Tracheal lesion easily closed, esophageal portion more difficult
- Rarely has associated stenosis

## C. Congenital stenosis
- Webs and diaphragms most often occur at subcricoid level
- Three types of stenosis: generalized hypoplasia, funnel-like narrowing, and segmental stenosis
- Main bronchi most often normal with generalized hypoplasia, vary in size with funnel-like narrowing, and commonly have anomalies with segmental stenosis
- Associated with a wide range of anomalies throughout the body
- About 50% of pulmonary sling cases are associated with lower tracheal stenosis

## D. Diagnosis of congenital stenosis
- Suspicion in infants with inspiratory and expiratory stridor or more severe respiratory distress
- Wheezing, retraction, poor feeding, failure to thrive may also be present

## E. Management
- Operations in infants are high risk, as postoperative edema may obstruct small airways and mechanical ventilation may disrupt anastomoses
- A conservative approach is wise, as less than 1/3 of the trachea in a child can be resected
- Webs can be dilated or excised endoscopically
- Stenoses should not be dilated, as this can create longitudinal tears, resulting in recurrent scarring and stricture
- Tracheostomy for palliation is a suitable alternative to allow growth for surgical repair

# Tracheal Neoplasms

## A. Primary neoplasms of the trachea are rare

## B. Squamous cell carcinoma
- Most common tracheal neoplasm
- Well localized exophytic or ulcerated lesion
- Multiple lesions or a superficially infiltrating variety also occur
- 1/3 of patients will present with mediastinal or pulmonary metastasis
- Spread is usually to regional tracheal lymph nodes and then directly into mediastinal structures

## C. Adenoid cystic carcinoma (cylindroma)
- Grows slowly and displaces mediastinal structures rather than invading
- Submucosal and perineural spread may occur for quite long distances
- Best chance at cure is complete resection at first operation

## D. Clinical Features
- Dyspnea on exertion
- Wheezing
- Stridor
- Excessive secretions
- Hemoptysis
- Pneumonia
- Cough

## E. Secondary tracheal neoplasms
- Thyroid cancers are the most common indication for tracheal operations for secondary malignancy
- Laryngeal carcinoma involves the upper trachea by direct extension
- Bronchogenic carcinoma more commonly involves the carina or bronchial origin on the right
- Tracheoesophageal fistula can result from radiation therapy for or from invasion by esophageal cancer
- Other tumor include carcinoid, head and neck, breast, and lymphoma

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

# Trauma

## A. Penetrating injuries
- Usually involve the cervical trachea
- Fresh injuries can be closed primarily

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

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

# Diagnosis
- CXR
- Fluoroscopy determines laryngeal function and presence of tracheomalacia
- CT to evaluate extramural extension of tumors
- Bronchoscopy and biopsy at the time of operation

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

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