Ashok Muniappan
INDICATIONS/CONTRAINDICATIONS
Tracheal dilation is indicated for relief of symptoms related to stenosis or obstruction caused by both benign and neoplastic conditions. Postintubation tracheal stenosis is the most common benign etiology requiring tracheal dilation. Other causes include neoplasms, trauma, inflammatory processes, and infection (Table 34.1). Secondary involvement of the trachea by a neoplasm is far more common than primary tracheal tumors.
Rigid bronchoscopy and tracheal dilation are indicated for the urgent relief of tracheal stenosis. Severe tracheal stenosis that is symptomatic is an emergency. A small amount of mucus or blood can completely obliterate the airway without warning and precipitate anoxia.
There are no absolute contraindications to tracheal dilation. Once the indication is established, the practitioner must select the appropriate method to most effectively deal with the airway narrowing. Tracheal dilation is often a prelude to a more definitive surgical procedure such as tracheal resection. Tracheal dilation on its own may not be effective or durable and familiarity with other techniques such as tracheal resection, T-tube insertion, or tracheal stenting is necessary.
PREOPERATIVE PLANNING
The patient often presents with a delay in diagnosis, and may have been treated as having “adult-onset asthma.” Important adjuncts for preoperative care of a patient with tracheal obstruction include airway humidification, oxygen, heliox, and mild sedation provided in an intensive care unit.
When the patient has any element of distress or there is concern about the security of the airway, advanced imaging of the airway by computed tomography (CT) is deferred. In a less severe presentation, CT scanning is useful for planning further interventions.
Assembly of a team proficient in airway dilation and management is paramount. Emergent airway dilation requires general anesthesia, and the anesthesiologist must be familiar with appropriate anesthetic technique. Tracheal dilation must be performed in an operating room suite with capability for flexible and rigid bronchoscopy as well as equipment and materials necessary for establishing a surgical airway if tracheal dilation is not possible or fails.
TABLE 34.1 Diagnoses Associated with Tracheal Stenosis or Obstruction
SURGERY
Anesthesia
General anesthesia is induced by either an inhalation or intravenous technique, and neuromuscular blockade is avoided until it is determined that the airway can be secured. If dilation and intubation beyond the stenosis do not appear straightforward, a temporary solution is jet ventilation through a rigid bronchoscope or endotracheal tube positioned proximal to the lesion, as long as there is a patent lumen. In most instances, slow and patient induction with an inhalational anesthetic delivered through a mask or laryngeal mask airway is sufficient. A flexible bronchoscope delivers 1% lidocaine topically to the vocal folds and mucosa of the subglottis, if bronchoscopy is performed without paralysis.
Positioning
Patients are positioned supine. A blanket or pillow may be placed beneath the occiput to improve alignment of the oral, pharyngeal, and laryngeal axis.
Technique
Rigid bronchoscopy is the standard technique for dilation of a benign stenosis in an adult. A complete set of equipment and materials for rigid bronchoscopy is mandatory (Table 34.2 and Fig. 34.1). A Jackson rigid bronchoscope is preferable as it has a gently rounded tip as opposed to the sharper spade-like tip of the Storz bronchoscope (Fig. 34.2). A blunt tip permits safe passage of the bronchoscope through a stenosis or tumor. A 7- or 8-mm Jackson rigid bronchoscope is used to examine the glottis and intubate the trachea, taking care to not travel into the stenosis. A suction device clears secretions that may have accumulated at the stricture. A rigid telescope, introduced through the rigid bronchoscope, enhances examination of the stenosis.
TABLE 34.2 Equipment and Materials Required for Rigid Bronchoscopy and Tracheal Dilation
Figure 34.1 Tip of Jackson and Storz rigid bronchoscopes. The gentle rounded tip of the Jackson bronchoscope (left) is more effective and considered safer for coring-out tumor and tracheal dilation compared to the sharp tip of the Storz bronchoscope (right).
Figure 34.2 Rigid bronchoscopes and bougie dilators. A: Jackson-Pilling esophageal bougies sized 10 to 16 Fr are used to dilate very tight strictures. B: Pediatric bronchoscopes (3.5, 4, and 5 mm), introduced with the assistance of a laryngoscope, are used to examine and dilate very tight strictures. C: Adult rigid bronchoscopes (6, 7, 8, and occasionally 9 mm) are used to further dilate strictures, core-out tumor, and remove blood and tissue.
Figure 34.3 Technique of rigid bronchoscopy and tracheal dilation. The rigid bronchoscope is positioned proximal to the stenosis to visualize the disease and remove secretions (A). An esophageal bougie is gently passed through the bronchoscope and stenosis (B), taking care not to perforate the distal airway. The tip of the bronchoscope engages the lumen at the level of the stenosis, and gentle rotatory motion is used to traverse the stricture (C). Normal caliber of trachea is seen once the bronchoscope has passed through the stricture (D).
Serial dilation of the tracheal stenosis with Jackson-Pilling esophageal bougies is performed through the 7-mm rigid bronchoscope (Fig. 34.3B). Care is taken not to pass the bougie beyond the stenosis so as to avoid perforation of the distal membranous wall of the trachea. Sufficient bougie dilation permits intubation of the stenosis with a Jackson pediatric rigid bronchoscope (3.5 to 5 mm). Pediatric bronchoscopes are best introduced with the aid of a laryngoscope. The tip of the bronchoscope engages the stenotic orifice and a gentle corkscrew motion is used to navigate the stenosis, which effectively dilates it (Fig. 34.3). Excessive force increases the risk of airway perforation or the raising of a mucosal flap. Serial dilation with adult bronchoscopes (6 to 8 mm) is performed next. Most stenoses are able to be dilated with at least a 7-mm rigid bronchoscope. Avulsed granulation tissue and scar are removed with a biopsy forceps, and all secretions are evacuated. A flexible bronchoscope introduced through the rigid bronchoscope is useful for clearing retained secretions in the distal tracheobronchial tree. There is little to recommend laser incision of a benign stenosis prior to dilation, as some have advocated. Such therapy often delays referral to a surgeon expert in tracheal reconstruction and more importantly extends the degree of tracheal injury, making surgery more difficult or impossible.
Rigid bronchoscopy is also effective for relief of neoplastic airway obstruction. Rigid bronchoscopic examination confirms that the tumor is not an arteriovenous malformation or hemangioma, rare lesions that must not be mechanically disrupted. Most neoplastic obstructions are safely cored-out with the rigid bronchoscope. Only rarely does a neoplasm involve the circumference of the airway, and in most patients there will be an orifice to work with. The beveled tip of the bronchoscope engages the orifice and a gentle rotatory motion through the tumor is used to core it out. Fragments of tumor are retrieved with forceps and a large suction cannula is passed through the rigid bronchoscope. Oozing from the base of the tumor is controlled with tamponade by the bronchoscope. Epinephrine-soaked pledgets (0.1 mg/mL) can be applied to the surface to control more troublesome bleeding. Although laser and cautery are not required in our experience, some practitioners use them routinely when debulking an airway tumor. Precautions to prevent airway fires are mandatory if these techniques are deployed.
An alternative technique for managing tracheal stenosis is balloon dilatation. There are no controlled studies that support tracheal balloon dilatation over rigid bronchoscopy. Balloon dilatation is felt to be less traumatic to the tracheal mucosa; on the other hand there is no tactile feedback to gauge whether or not the trachea is yielding to dilation, increasing the risk of perforation. Balloon dilatation appears to be most appropriate for bronchial stenosis and pediatric airway dilation.
POSTOPERATIVE MANAGEMENT
After tracheal dilation, either an orotracheal tube or laryngeal mask airway is placed. Most patients that undergo tracheal dilation are extubated in the operating room once they are sufficiently awake and able to generate a cough reflex. If the patient is noted to have significant pulmonary compromise prior to the procedure, secondary to atelectasis or pneumonia, a brief period of positive pressure ventilation with an endotracheal tube can be beneficial. Antibiotic therapy is indicated if there is evidence of bacterial tracheobronchitis or pneumonia. Steroids are administered if there is concern of glottic edema, which is sometimes exacerbated after rigid bronchoscopy. All patients merit observation in a unit expert in respiratory care. Vigilance for recurrent symptoms is mandatory, as the effect of dilation may be very transient. Certain lesions, such as a stomal stenosis, are predictably refractory to dilation as the abnormal cartilage resists durable stretching. These patients are better served by definitive tracheal resection and reconstruction whenever possible and consideration of T tubes or other airway appliances when surgery is contraindicated.
COMPLICATIONS
Serious complications after tracheal dilation are exceedingly rare when carefully performed by an experienced operator. The most serious complications are related to airway perforation. Disruption of the airway leads to pneumomediastinum and on occasion pneumothorax, which requires tube thoracostomy. If there is concern about rupture of the membranous wall of the trachea, esophagoscopy is indicated to rule out full-thickness esophageal injury. Core-out of tracheal neoplasms sometimes causes postprocedure hemorrhage that almost always responds to the conservative measures mentioned above. It is important to verify that patients have normal coagulation parameters before performing tracheal dilation and tumor core-out.
RESULTS
There are no controlled studies directly comparing the results of tracheal dilation with tracheal resection and reconstruction. Retrospective analysis suggests that tracheal dilation for a benign stenosis generally requires chronic reintervention or an airway appliance such as tracheostomy or T tube. A small minority of patients has a durable effect from dilation and can avoid further treatment.
Rigid bronchoscopy and core-out of tracheal tumors has been found to be very effective, in our experience. We observed that a single bronchoscopy was sufficient to improve the airway in over 90% of patients presenting with malignant airway obstruction. Complications occurred in 11 of 56 patients and included pneumonia in five, bleeding in three, pneumothorax in two, and laryngeal edema in one. Approximately 30% of the patients went on to have definitive resection.
CONCLUSIONS
Tracheal dilation is potentially a life-saving technique for a patient presenting with severe critical airway obstruction. Safe and effective dilation requires careful coordination with anesthesia, access to a wide range of instruments, and most importantly a dedicated team with experience caring for such patients. In most patients, tracheal dilation is only a temporary measure and serves as a bridge to more definitive care such as tracheal reconstruction or T-tube insertion.
Recommended References and Readings
Chang AC, Pickens A, Orringer MB. Awake tracheobronchial dilation without the use of rigid bronchoscopy. Ann Thorac Surg. 2006;82:43–45.
Herrington HC, Weber SM, Andersen PE. Modern management of laryngotracheal stenosis. Laryngoscope. 2006;116:1553–1557.
Mathisen DJ, Grillo HC. Endoscopic relief of malignant airway obstruction. Ann Thorac Surg. 1989;48:469–475.
Thistlethwaite PA, Yung G, Kemp A, et al. Airway stenoses after lung transplantation: Incidence, management, and outcome. J Thorac Cardiovasc Surg. 2008;136:1569–1575.