Airway neoplasms account for approximately 90% of carinal resections.¹ The incidence of primary tracheal tumors is unclear, but is known to be rare. A recent population-based cancer registry analysis using the SEER database demonstrated an incidence of 2.6 tracheal tumor cases per 1,000,000 people per year.² Carinal tumors, as a subcategory of tracheal tumors, are even less common. Most are malignant and can be divided into bronchogenic carcinoma and other airway neoplasms. Bronchogenic carcinomas are by definition malignant; the other airway neoplasms may exhibit a wide range of behavior. As demonstrated in Table 64-1, the most common malignant primary tracheal neoplasms are squamous cell carcinoma (SCC) and adenoid cystic carcinoma (ACC).³ SCC occurs primarily in smokers in their sixth and seventh decades and may present confined to the trachea or invading into adjacent mediastinal structures. ACC is an exophytic intratracheal lesion, which may involve the tracheal wall to variable extent (Fig. 64-1), and compress mediastinal structures without invading them initially. Lymph node metastases occur, but less commonly than in SCC. A characteristic feature of ACC is its proclivity for extending long distances submucosally and perineurally.

Patients commonly present with symptoms and signs of central airway obstruction. They have worsening dyspnea, often progressing to wheezing and/or stridor as the diameter of the airway decreases. Dyspnea on exertion occurs when the airway diameter is less than 8 mm and stridor develops with airways less than 5 mm.⁴ Chest radiographs may demonstrate a mass in the tracheobronchial airway column. These findings are often subtle and are usually missed. Consequently, patients are commonly given a diagnosis of adult-onset asthma, and diagnosis is delayed. Patients presenting with either postobstructive pneumonia or a cough with hemoptysis may have their tumors diagnosed more rapidly. Extensive tumors may result in hoarseness, dysphagia or chest discomfort suggesting more diffuse or extensive mediastinal invasion.

Chest radiographs can appear normal despite significant tracheobronchial obstruction, but careful evaluation often demonstrates the outline of the mass within the airway column. Until recently, carinal tomograms were useful, revealing the location and extent of the lesion, permitting the assessment of the uninvolved proximal and distal airway. Virtually all the essential information was provided in a single view, giving the surgeon an accurate assessment of the lesion’s extent. Recently, computerized tomograms have virtually replaced the use of carinal tomograms. The use of high-speed, multidetector helical CT scanners to acquire images combined with the powerful 3D-image reformation software has created impressive two and three dimensional airway reconstructions (Fig. 64-2A,B). In addition, computerized tomograms have proven critical in evaluating extraluminal extension and enlarged regional mediastinal lymph nodes; something conventional tomograms could not provide (Fig. 64-2C).

When a high degree of obstruction exists, the airway can be reopened endoscopically. This palliates acute symptomology and allows a greater degree of preoperative assessment and preparation, as well as the safe delivery of anesthesia. Specifically, patients with postobstructive pneumonia benefit from having the obstruction relieved, the pneumonia treated and the central airways cleared of purulence in advance of definitive resection and reconstruction (Fig. 64-3A–D). This is accomplished using a ventilating rigid bronchoscope under general anesthesia, without respiratory paralysis. Using the tip of the bronchoscope as a coring device, the side with the least obstruction is cleared first. Significant bleeding is rarely a problem, and can be handled with the usual techniques of rigid bronchoscopic tamponade and the judicious use of topical epinephrine solution or iced saline. Unimpeded bronchoscopic examination can then be undertaken.⁵

Metastatic workup is similar to that for lung cancer and should include chest CT, brain MRI, and PET scan to assess extraluminal extension, nodal basins, and distant metastases. Bronchoscopy allows tissue diagnosis and reveals the intraluminal extent of the tumor. Mediastinoscopy is ideally reserved for the day of resection to assess resectability, evaluate regional lymph node status and to begin central airway mobilization. By performing the mediastinoscopy at the time of planned resection, the scarring and decreased mobility associated with a staged approach is avoided. Patients with bronchogenic carcinoma and N2 disease should be considered to have unresectable disease, and surgery should only be performed in a protocol setting. Patients with ACC may benefit from resection despite nodal involvement.⁶

Anesthesia

An experienced anesthesiology team working in close cooperation with the surgical team is essential to achieve successful carinal resection. Placing a patient with a partial airway obstruction under general anesthesia is potentially hazardous. Replacement of spontaneous breathing with positive-pressure ventilation can convert a partially obstructing lesion into a complete obstruction. When maintenance of the airway is a concern, a “breathe down” technique with an inhalation agent is employed and paralytics are given only after the airway is secured. This allows the patient to breath spontaneous during the induction process, maintaining favorable respiratory physiology. Once a stable airway is secured, anesthesia is maintained with total intravenous anesthesia (TIVA) using short-acting agents such as remifentanil and propafenone. This allows immediate extubation at the completion of the procedure and maintains continuous anesthesia during periods when inhalational agents would be interrupted by the apneic intervals necessary to complete the procedure.

The administration of anesthesia through a rigid bronchoscopy during tumor “core-out” can be accomplished with either standard volume ventilation or with “jet” ventilation. Ventilating rigid bronchoscopes do not have balloon cuffs and by necessity have an open top to allow the passage of instruments. With standard volume ventilation there is a substantial air leak around the tip of the bronchoscope and out through the partially open top. Despite the use of a rubber diaphragm through which to introduce instruments, the seal is imperfect, and substantial volume is lost. Consequently, higher gas flow is required to compensate for this loss in effective tidal volume. Assessing effectiveness of ventilation is performed by observing adequate chest excursions rather than end-tidal CO₂, since returning gases leak out from the circuit. With “jet” ventilation, gas is delivered at high pressure at the source, resulting in higher flow rates and higher effective tidal volumes. The top of the bronchoscope must be left open to allow venting of excess volume/pressure to reduce the risk of barotrauma. Both methods are safe and effective in experienced hands. When thermoablative devices are employed, special precautions are mandatory to prevent airway fires. Ventilation at low FiO₂ combined with periods of apnea prior to ignition of thermal devices (allows dispersion of oxygen) is employed. Clear communication and precise coordination with the anesthesiologist is essential.

Anesthesia for carinal resection is administered through an extra-long, armored endotracheal tube. Its flexibility allows bronchoscopic placement into one of the mainstem bronchi. After transecting the airway, the orotracheal tube is pulled back into the trachea and intermittent ventilation is performed with sterile cross-field equipment. The orotracheal tube is again advanced once the anastomosis is completed (Fig. 64-4). Occasionally, “jet” ventilation is useful when the left main bronchi is surgically foreshortened and will not accommodate an endotracheal balloon cuff. The small caliber of the tubing and lack of a balloon cuff allow for a less cluttered operative field and improved exposure for suture placement. However, the high-velocity airflow coupled with an open airway allows blood and airway secretions to mix and become sprayed into the lungs and the operative field. This potentially increases the risk of both pleural and pneumonic infections. In addition, the anesthesiology team must be proficient with the techniques of high-frequency “jet” ventilation. Excessive ventilation without time for passive exhalation results in hyperexpansion injury to the lung parenchyma. Inadequate “jet” ventilation results in a slow reduction in FRC as there is no mechanism to provide the PEEP necessary to prevent alveolar collapse. The risk of ARDS is higher when “jet” ventilation is employed.⁷ Cardiopulmonary bypass is generally not helpful, and only introduces unnecessary risks. A rare circumstance may arise where it is required.

Operative Procedure

Mediastinoscopy is performed on the day of proposed surgery not only to assess nodal status and resectability, but to facilitate the resection and reconstruction by mobilizing the pretracheal plane while visualizing the recurrent laryngeal nerve. Scarring of the pretracheal plane from prior mediastinoscopy limits airway mobility, complicates reconstruction, and increases the likelihood of injury to the left recurrent laryngeal nerve. Scar tissue also may be difficult to distinguish from tumor.

Choice of the operative approach is dependent on the type of carinal resection as well as personal preference. Carinal resection alone or carinal resection with right pneumonectomy can be comfortably performed through either a right thoracotomy or median sternotomy. Both approaches have their proponents.^8,9 The bias of the authors is toward the right thoracotomy approach and is discussed below. Carinal resection with left pneumonectomy presents a unique challenge and is discussed later.

A standard right posterolateral thoracotomy in the fourth interspace creates excellent exposure of the carina and allows for most resections through a single incision. When tumor extension down the left main bronchus precludes carinal reconstruction following complete resection, median sternotomy, bilateral thoracotomies, or extended clam-shell incision should be used since they permit sleeve pneumonectomy.

Once the right lung is collapsed and retracted anteriorly, the pleura overlying the carina is incised and the carina exposed. Division of the azygos vein facilitates exposure. The carina should be circumferentially freed by dissecting on the airway and avoiding the left recurrent laryngeal nerve. Dissection should be kept to a minimum and skeletonization of the airway limited to only the diseased segment to be resected (Fig. 64-5). Likewise, a balance must be struck between achieving adequate lymphadenectomy and maintaining tracheobronchial blood supply. Tapes are placed around the trachea and both mainstem bronchi. The inferior pulmonary ligament is released to allow greater mobility of the right lung, and equipment for cross-field sterile ventilation is prepared. The order of dividing the airway structures varies, but commonly the trachea is divided first. Preoperative bronchoscopic assessment by the surgeon directs the tracheal division to just proximal to the tumor. An adequate margin can then be taken under direct visualization in the form of a complete ring sent separately for intraoperative frozen section. The endotracheal tube is then removed to allow division of both mainstem bronchi under direct endobronchial visualization. Adequate margins are taken of both distal bronchi and sent separately for frozen section. Only the left mainstem bronchus is reintubated, usually across the field, maintaining collapse of the right lung.