Surgical Management of Upper Airway Stenosis

Key Points

Accurate preoperative assessment of laryngotracheal stenosis is critical to a successful repair; it includes the use of multiple staging systems to evaluate diameter and levels of airway stenosis.
The primary goals of surgical intervention are to establish an adequate airway and enable eventual decannulation.
Timing of surgical intervention is important; chronic airway stenosis may be electively repaired following proper preoperative evaluation of possible inflammatory and autoimmune etiologies in idiopathic stenosis cases.
Endoscopic and open approaches for repair are acceptable. The advent of microlaryngeal instrumentation, balloon dilation instrumentation, and distal chip endoscopes has enabled endoscopic management and decreased morbidity of larger open procedures but may require more frequent procedures.
Endoscopic treatment options include microsurgical débridement or laser therapy with dilation, possibly with the use of injected steroids and topical applications such as mitomycin C.
Successful surgical repair hinges on providing an adequate skeletal framework as scaffolding, followed by the need for grafts to avoid scarring and tethering.
Sources of cartilage grafts include vascularized thyroid and hyoid, auricular and nasal cartilages, and more recently tracheal allotransplants.
Stents are useful in limited instances, with the need to maintain a patent airway balanced by the risk of ischemic mucosal injury and increased risk of infection of underlying grafts.
Controversy surrounding the effect of endotracheal intubation that leads to airway stenosis from compression has led to improvements in endotracheal tube design; the largest impact has been on the size of the tube and the pressure and volume of its cuff on the posterior glottic region.
Traumatic laryngotracheal injury may lead to airway stenosis, and surgical intervention ranges from tracheostomy to tracheal resection with postoperative stent placement.

Pathophysiology

Adult laryngotracheal stenosis has numerous potential etiologies ( Box 67.1 ). The pathophysiology of the specific cause plays a significant role in determining the appropriate surgical management options.

Box 67.1

Data from references .

Causes of Adult Laryngeal and Upper Tracheal Stenosis

Trauma

Internal Laryngotracheal Injury

Prolonged endotracheal intubation
Tracheostomy
Endoluminal surgical procedure
Endotracheal burn
- Thermal
- Chemical
Laryngopharyngeal reflux

External Laryngotracheal Injury

Blunt neck trauma
Penetrating injury of the larynx
Radiation therapy

Chronic Inflammatory Disease

Autoimmune
Granulomatosis with polyangiitis
Sarcoidosis
Relapsing polychondritis
Granulomatous infection
Tuberculosis

Neoplasms

Benign

Papillomas
Chondromas
Minor salivary gland neoplasms
Neural neoplasms

Malignant

Squamous cell carcinoma
Minor salivary gland neoplasms
Sarcomas
Lymphoma

The most common cause of laryngotracheal stenosis is prolonged endotracheal intubation. The injury from endotracheal intubation is usually initiated by ischemic necrosis of the mucosa from pressure of the cuff of the endotracheal (ET) tube or from the tube itself. Mucosal ulceration in the presence of bacterial infection can lead to perichondritis and chondritis with subsequent cartilage resorption. Patients can come to medical attention during this process with acute stenosis secondary to granulation tissue and acute inflammation. Chronic stenosis occurs because healing by secondary intention results in submucosal fibrosis and scar contraction. Stenosis may result from soft tissue scaring, cartilaginous remodeling, or both. Injuries from ET intubation occur primarily in the posterior glottis as a result of pressure exerted by the wall of the tube at the level of the glottis and the pressure of the cuff at the level of the subglottis. With the widespread acceptance and the use of ET intubation to provide ventilatory and airway support, efforts have been directed toward modifying the tube size and composition as well as cuff volume and pressure to minimize injury risk. Other factors that may influence the risk of laryngotracheal stenosis include duration of intubation, lack of proper sedation, medical comorbidities interfering with wound healing or capillary perfusion (e.g., cardiovascular lability, poorly controlled diabetes, hypothyroidism, and gastroesophageal reflux), and laryngeal movement.

External trauma may also injure the laryngotracheal complex, the result of which is usually disruption of the cartilaginous framework, hematoma in the laryngeal spaces, and mucosal disruption—any of these can cause acute airway stenosis. Airway narrowing may be a consequence of loss of the rigid laryngotracheal framework and subsequent collapse, or intraluminal fibrosis and contracture. Pressure from the hematoma or direct injury to the cartilage can cause cartilage loss and extensive deposition of collagen, and subsequent loss of structural rigidity scar contracture leads to chronic stenosis and loss of mobility. The location, mechanism, and severity of the laryngeal injury caused by external trauma vary.

Patient comorbidities and systemic diseases have also been shown to be correlated with the development of subglottic and tracheal stenosis. Diabetes mellitus, congestive heart failure, and a history of stroke have been shown to be associated with a higher incidence of severe acute laryngeal injury from intubation. In some cases, this condition prompts early tracheostomy. Additionally, for patients with idiopathic airway stenosis who have no significant history of intubation, trauma, or laryngeal surgery, a thorough autoimmune evaluation should be performed. A significant proportion of patients with subglottic stenosis may carry a diagnosis of granulomatosis with polyangiitis (previously known as Wegener granulomatosis). These patients often require more procedures, longer follow-up periods, and potentially systemic therapies. Laryngopharyngeal reflux in the setting of gastroesophageal disease has been associated with laryngotracheal stenosis as a potential causative factor. Treatment with H2 blockers and proton pump inhibitors in the perioperative and acute injury phases has been demonstrated to prevent scar formation and subsequent contracture.

Classification of Stenosis

Multiple staging systems exist for airway stenosis. As shown in Table 67.1 , these classifications are based on the function or location of the stenotic section:

The Myer-Cotton classification: Originally developed for subglottic stenosis, now the most widely used staging system.
The McCaffrey classification: Adds to diagnostic and therapeutic planning by providing a prediction of prognosis following surgery.
The Bogdasarian and Olson classification: Guides treatment planning for posterior glottic stenosis.

TABLE 67.1

Classification and Staging Systems for Airway Stenosis

M yer -C otton C lassification : C ircumferential S tenosis L imited to S ubglottic R egion
Grade I	Obstruction of 0%–50% of the lumen
Grade II	Obstruction of 51%–70% of the lumen
Grade III	Obstruction of 71%–99% of the lumen
Grade IV	No detectable lumen; obstruction of 100% of the lumen
M ccaffrey C lassification : L aryngotracheal S tenosis B ased on the S ubsites and L ength of the S tenosis
Stage I	Subglottic or tracheal lesions <1 cm long
Stage II	Subglottic lesions >1 cm long, not extending into the trachea
Stage III	Subglottic lesions extending into the upper trachea but do not involve the glottis
Stage IV	Subglottic and tracheal lesions involving the glottic lesions, with fixation or paralysis of one or both vocal folds
B ogdasarian and O lson S taging : P osterior G lottic L aryngeal S tenosis
Stage I	Adhesion of the vocal process
Stage II	Scarring of the interarytenoid plane and internal surface of the posterior cricoid lamina
Stage III	Unilateral cricoarytenoid joint ankylosis
Stage IV	Bilateral cricoarytenoid joint ankylosis

Surgical Principles

Goals and Assessment

Successful repair of upper airway stenosis requires establishing an adequate airway, allowing for decannulation, and preserving the laryngeal functions of airway protection, phonation, and sustained glottic closure to allow for increasing intrathoracic pressure. Selection of the appropriate surgical repair should consider all these factors in the context of the patient's concurrent injuries, functional status, and medical stability. Surgical procedures designed to improve the airway often compromise other laryngeal functions. The anticipated overall function of the larynx should be carefully discussed with the patient so that expectations are reasonable.

Several factors should be considered that include the location, dimensions, and quality (soft vs. fibrous) of the stenosis; associated vocal fold motion impairment; and extent of functional impairment. Initial evaluation should involve a thorough history that includes details of the degree of subjective impairment along with objective measures, such as exercise tolerance and pulmonary function testing. The latter may be helpful in delineating the site of the obstruction quality (fixed versus variable obstruction) and the severity of the airway compromise. Fixed obstruction will demonstrate a plateau of flow rates for both inhalation and exhalation, whereas variable obstruction, either intrathoracic or extrathoracic, will demonstrate a plateau of flow rate on exhalation or inhalation, respectively ( Fig. 67.1 ).

Fig. 67.1, Flow-volume loop for assessing adequacy of the upper airway.

Physical examination that includes an indirect laryngeal examination followed by direct laryngoscopy and bronchoscopy is essential. Subglottic evaluation may be aided with the use of topical laryngotracheal anesthesia. If a tracheostomy is in place, endoscopy through the stoma with retroflexion may be of utility. High-resolution computed tomography of the larynx and trachea may be useful in assessing the level and length of the stenosis and if there is suprastructural collapse. Three-dimensional computed tomography with volume rendering ( Fig. 67.2 ) or virtual endoscopy is a tool of potential benefit that provides a “surgeon's view” of the stenosis. Additional adjuvant testing may be used in selected patients, based on symptoms and surgeon concerns: videostroboscopy, modified barium swallow, or fiberoptic endoscopic examination of swallowing (FEES) or laryngeal electromyography (EMG).

Preoperative evaluation is aimed at determining the appropriate surgical approach to manage the airway stenosis. Surgery for laryngotracheal stenosis can be grouped into three categories: open procedures with resection and reanastomosis, reconstruction with augmentation or grafting, or endoscopic procedures. Often, patients may need multiple surgeries, with criteria for success generally being defined as the number of additional procedures required and ultimate decannulation for tracheostomy patients. Open treatments typically involve more extensive surgery and are associated with a greater variety and sometimes greater severity of complications. Open repair, however, can provide definitive treatment when endoscopic treatment has failed or is unlikely to provide a permanent adequate solution. Several factors are involved in the determination of endoscopic versus open repair options. Tracheal or cricotracheal resection and anastomosis offer excellent decannulation rates, however in patients with long segment stenosis greater than six tracheal rings, this procedure has more limited success and reconstruction or laryngotracheoplasty is preferred. Endoscopic surgery is associated with poor outcomes when cicatricial contracture, scarring wider than 1 cm in vertical dimension, tracheomalacia and/or loss of cartilage, previous history of severe bacterial infection associated with tracheostomy, or posterior laryngeal inlet scarring with arytenoid fixation are present. A history of blunt or penetrating trauma is correlated with the highest rates of need for multiple surgical procedures. A systematic review found that patients with idiopathic stenosis are less likely to receive further surgery (25%) compared to those with a history of intubation, trauma, or surgery (35% to 54%), but have the lowest rate of successful decannulation at 63%. Although expertise and choice of surgery tend to dictate success of open procedures, patient factors that may impact restenosis or need for additional procedures include high grade of stenosis, advanced age, body mass index (BMI), medical comorbidities, and history of radiation to the laryngotracheal region or neck.

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