Bronchoscopic Evaluation

Bronchoscopy is essential in the evaluation of the patient with central airway obstruction who may be a candidate for airway stenting. Bronchoscopy is also useful for delivery and adjustment of an endoluminal stent and is preferred for refining the accuracy of stent delivery by a majority of pulmonary physicians and thoracic surgeons. Although stents may also be placed under fluoroscopic guidance without bronchoscopy, initial evaluation of the airway by bronchoscopy is critical to assess the nature of the obstructing lesion and the appropriateness for airway stenting. Bronchoscopy should be performed on any patient with symptoms of central airway obstruction combined with a history of prolonged mechanical ventilation or tracheo-stomy. Other patients with a history or findings suggestive of a potential tracheobronchial stenosis should also prompt bronchoscopic inspection, since imaging studies are not yet sensitive or specific enough to replace direct visualization of the airways.

Bronchoscopy performs five critical functions in the evaluation and treatment of patients with symptomatic central airway obstruction: 1) definition of the existence and pathology of the airway abnormality; 2) temporary stabilization of the critically narrowed airway; 3) definition of the extent, severity, and complexity of the stenosis; 4) assessment of the treatment modalities that may be successful given the pathology and anatomy; and 5) direct therapeutic bronchoscopic intervention for temporary or long-term airway palliation.

When the pathology of a tracheobronchial stricture is unknown, biopsies should be obtained to establish a diagnosis. Establishment of a stable airway and adequate access for secure ventilation is the top priority and should take place simultaneously with the initial bronchoscopic assessment. A careful map of the airway anatomy should be created that defines the extent of the lesion and its relation to the normal airway anatomy; that is, directly measuring the distance of the stenosis from the vocal cords, cricoid cartilage, carina, and if necessary, the length of the mainstem bronchi and bronchus intermedius. The anatomy should be clearly documented along with the associated findings of granulation tissue, mucosal inflammation, or loss of cartilaginous support. This assessment should document the length and severity of stenosis as well as the degree of stenosis due to endoluminal disease versus fibrotic scar or extrinsic compression. The initial bronchoscopy should also evaluate the remainder of the airway for signs of postobstructive inspissated secretions, inflammation, or infection.

When the initial bronchoscopic assessment has defined the pathology and anatomy, it is easier to choose the optimal therapeutic approach. Patients with central T3-4 N0-1 nonsmall cell lung cancer are usually best treated by an extended surgical resection with a sleeve lobectomy or sleeve pneumonectomy, as discussed earlier in this text. Patients with benign strictures of the trachea or patients with tracheal tumors that involve less than half the length of the trachea may usually be definitively treated with primary tracheal resection and reconstruction. Tumor or granulations can be debulked by mechanical core-out with the tip of the bronchoscope or biopsy forceps. In some cases, this may be augmented by laser vaporization. Benign or malignant strictures can be dilated with esophageal bougies, with serially sized rigid bronchoscopes, or with hydrostatic balloon dilatation. Patients with significant extrinsic compression or malacia, however, do not have other directly applicable strategies other than airway stenting. Stenting also provides an adjunct to debridement of an intraluminal lesion if the initial therapy fails or has the appearance of likely early failure (see Figure 40-7). Similarly, stenting provides a useful adjunct to the dilation of a benign stricture to maintain patency, with less need for repeated dilations.

The endoscopic techniques for airway palliation are not mutually exclusive. Each of these modalities, including definitive surgical correction, should be available and considered by the physician evaluating a patient with symptomatic central airway obstruction. The treatment can then be tailored to fit the pathology and anatomy, with treatments combined to achieve the optimal patient outcome.1 An algorithm for the application of therapeutic bronchoscopy to central airway obstruction, including stenting, is provided in Figure 40-8.

Many authors have come to favor either flexible bronchoscopy or rigid bronchoscopy for their therapeutic interventions. A number of pulmonary physicians and thoracic surgeons alike have abandoned rigid bronchoscopy in favor of the relative ease of flexible bronchoscopy. However, in patients with central airway obstruction and complex airway anatomy, rigid bronchoscopy provides a spectrum of airway interventions that are not easily duplicated by flexible bronchoscopy. Although rigid bronchoscopy has the disadvantage of requiring a general anesthetic, it has the significant advantage of providing ventilation concurrent with air-

figure 40-8 Algorithm for management of central airway obstruction

way assessment, and allowing the endoscopist to directly secure airway control distal to a critical stenosis. Rigid bronchoscopy has the advantage of larger instrumentation to facilitate mechanical d├ębridement of endoluminal tissue and aspiration of secretions and blood.

The availability of rigid bronchoscopy is especially important for airway stenting since rigid bronchoscopy allows delivery of silicone or expandable stents. This allows the choice of the best stent for the patient and anatomy rather than a stent chosen because of the inability to deliver a nonexpandable stent. Furthermore, it is much easier to manipulate, adjust, and even remove stents by rigid bronchoscopy. Although expandable stents are typically considered permanent, most of these can be removed, albeit with significant difficulty, by rigid bronchoscopy, even after the development of tissue ingrowth. Flexible bronchoscopy provides little ability to adjust expandable stents once they have become firmly seated within the airway.

Flexible bronchoscopy has the advantage of allowing excellent airway assessment in an endoscopy suite without general anesthesia. Flexible bronchoscopy also allows an easier assessment of the lobar and segmental orifices than rigid bronchoscopy does. The increasingly sophisticated instrumentation available for the flexible bronchoscope allows dilation of strictures, retrieval of foreign bodies, and manipulation of airway prostheses. However, this is a far more limited repertoire than that available to the endoscopist skilled in rigid bronchoscopy. Flexible bronchoscopy has the added disadvantage of exacerbating the obstruction by the diameter of the bronchoscope, although this may be minimized by use of pediatric bronchoscopes. This may not allow distal airway evaluation in critical tracheal stenosis until after dilatation.

The complete interventional bronchoscopist should be skilled and adept in both rigid and flexible bronchoscopies. The bronchoscopist should have a broad spectrum of instrumentation and a team that is familiar and comfortable with both approaches to the airway. Although the skills and procedures for therapeutic bronchoscopy are not particularly difficult, application of these skills is challenging in the patient with a severely compromised airway, even for physicians with significant experience in airway therapeutics. Because of this, maintenance of skill in rigid bronchoscopy is critical so that this expertise can be readily available when a patient presents with a complicated and threatened airway.

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