Ashok Muniappan
INDICATIONS/CONTRAINDICATIONS
Tracheal stenosis or obstruction most commonly develops in the setting of postintubation injury (stomal or cuff injury), primary and secondary tumors of the airway, and trauma, in order of decreasing frequency. Patients are symptomatic when the cross-sectional area is reduced by more than 50% or the diameter of the tracheal lumen is less than 5 to 6 mm. Tracheal resection and reconstruction (TRR) may be appropriate for definitive correction of all of these conditions. Tracheal resection is distinguished from laryngotracheal resection in that the lesions are confined to the trachea and do not involve the cricoid or subglottic airway.
TRR is generally not appropriate for patients requiring mechanical ventilatory support, as positive airway pressures predispose to anastomotic complications. TRR is also inadvisable in patients requiring a high dose of corticosteroid, which can impair healing. Extended lesions of the trachea that involve more than half its length may not be resectable as anastomotic tension may be too great. Advanced age, obesity, short stature, kyphosis, and prior tracheal or mediastinal surgery must also be factored when selecting patients for TRR. When TRR is undertaken for an airway neoplasm, it is important to rule out distant metastasis or invasion of a mediastinal structure that cannot be resected.
PREOPERATIVE PLANNING
Plain chest radiography may identify an abnormal tracheal air column and establish the level of the tracheal pathology. Computed tomography (CT) is much more sensitive and provides more accurate localization and measurement of tracheal disease. Inspiratory and expiratory CT imaging can visualize dynamic obstruction, for instance when tracheomalacia is responsible for inspiratory collapse of the trachea. CT is vital for evaluation of neoplastic disease, as it determines whether or not there is invasion of adjacent mediastinal structures or if there is evidence of distant metastatic disease.
Bronchoscopy is much more specific and sensitive than imaging in the evaluation of tracheal disorders. Tracheal narrowing may be over- or underestimated on imaging studies. Bronchoscopy is used to measure the extent of the lesion and determine whether a lesion is resectable. Rigid bronchoscopy is the most versatile technique as it is not only diagnostic but also therapeutic when used to dilate critical airway stenoses. Rigid bronchoscopy and core-out of tracheal neoplasms restores the airway and provides tissue for histologic diagnosis. There is virtually no indication for emergent TRR, and bronchoscopic management is sufficient to assess and stabilize the patient’s airway.
When a patient’s condition requires prolonged mechanical ventilation, a tracheostomy may be necessary. The stoma is carefully located in the diseased segment of the trachea so as to not extend the amount of diseased trachea that would eventually require resection. It is important to wean patients from mechanical ventilation before undertaking TRR. Similarly, patients requiring high-dose corticosteroid therapy are weaned completely or to a very low dose prior to TRR.
SURGERY
Anesthesia
Induction of anesthesia is performed with the surgeon present. A laryngeal mask airway may be sufficient for ventilation and permits flexible bronchoscopy. A rigid bronchoscope must be available if anesthetic induction leads to complete airway obstruction. Jackson bougie dilators and small ventilating rigid bronchoscopes (3 to 5 mm size) are effective at dilating very tight strictures. Once dilation is completed, the anesthesiologist may intubate with a size 5 to 6 orotracheal tube. A pediatric flexible bronchoscope may facilitate navigation of the tube through the stenosis.
Positioning
Patients are positioned supine with a bag inflated under their shoulders to extend the neck; a gel pad supports the occiput (Fig. 35.1). The arms are left at the sides, and the knees and hips are slightly flexed so as to prevent blood pooling in the lower extremities. The patient is prepped from the chin to just beneath the xiphoid.
Technique
A low cervical collar incision is made and subplatysmal flaps are raised (Fig. 35.2). The superior flap should be at least to the level of the cricoid cartilage and the inferior flap is made down to the sternal notch. Gelpi retractors are used to distract the flaps and maintain exposure (Fig. 35.3). On occasion, a cervicomediastinal approach is necessary if the lesion is in the lower half of the trachea (Fig. 35.4). In this case, a T-shaped incision, including the low-collar component and an extension in the midline down to the sternal angle is made. The sternum is divided in the midline down to the angle and a pediatric chest spreader distracts the manubrium. Total sternotomy does not enhance exposure. A right thoracotomy is generally only necessary for the most distal tracheal resections, which approach the carina. The collar incision may have to circumscribe a tracheal stoma, when one exists (Fig. 35.2).
The midline anatomy is established by dissecting down to the anterior surface of the trachea. The sternohyoid and sternothyroid strap muscles are mobilized and retracted with a Weitlaner retractor. The thyroid isthmus is divided if it has not been previously. Anterior dissection right on the airway is performed to isolate the tracheal pathology. As the tracheal vasculature is segmental and enters laterally, circumferential dissection must be restricted to the lesion that is to be resected. As the surface appearance of the trachea does not always reveal the location of the endoluminal pathology, bronchoscopic transillumination at the stenosis or tumor allows marking sutures to be placed on the surface, to guide further dissection and plan airway division. The endotracheal tube may need to be pulled back to visualize the endoluminal disease.
Figure 35.1 Patient positioning. A bag is inflated beneath the shoulders, extending the neck. The arms are by the side. The table is adjusted to flex the patient at the hips and knees.
Figure 35.2 Low collar incision. The low collar incision provides adequate exposure for proximal and midtracheal lesions. When there is a pre-existing tracheostomy, the incision either incorporates it (A), or is placed beneath it if the stoma is high in the neck (B).
Figure 35.3 Cervical exposure. Gelpi retractors on either side of the incision retract the subplatysmal flaps. A Weitlaner retractor distracts the strap muscles. The divided ends of the thyroid isthmus are retracted by suture ligatures.
Figure 35.4 Cervicomediastinal exposure. When the tracheal lesion is more distal, mediastinal exposure is necessary. Here a low collar incision is extended in the midline down to the sternal angle, in a T configuration (A). The manubrium is divided and retracted with a pediatric chest spreader (B).
Figure 35.5 Tracheal division and cross-field ventilation. The lesion is most often divided at its distal extent (A) unless the lesion is distal (B). An endotracheal tube is introduced into the distal trachea and connected to sterile ventilator tubing on the field.
The trachea is generally divided just distal to the lower end of the stenosis or tracheal tumor (Fig. 35.5). The indwelling tube’s cuff is deflated prior to incision, and then withdrawn once the distal tracheal lumen is identified. A red rubber catheter is attached to the tip of the endotracheal tube before it is withdrawn and will facilitate later replacement of the orotracheal tube (Fig. 35.6). Cross-field ventilation is established by intubating the distal tracheal segment with a 6-0 endotracheal tube in the surgical field, and connecting it to sterile ventilator circuit tubing that was previously passed off to the anesthesiologist. The segment of the trachea containing the stricture or tumor is dissected and divided proximally. The recurrent nerves are avoided by maintaining dissection right on the airway. A single recurrent nerve may have to be sacrificed if it is involved by tumor, as in the case of an invasive thyroid cancer. Lateral stay sutures of 2-0 vicryl are placed in the midlateral wall in both ends of the trachea and facilitate further dissection (Fig. 35.7). The stay sutures should encircle at least one cartilage ring and be placed more than one ring away from the cut edge. The stays may be replaced if it is determined that additional trachea must be resected. It is important to not resect too much trachea to avoid excessive anastomotic tension. After a segment is cautiously resected, the anesthesiologist flexes the neck by picking up the head and brings the chin toward the sternum (Fig. 35.8). The stay sutures are brought together to determine whether the tracheal ends come together with minimal tension. Rarely, when extended resections would produce increased anastomotic tension, a laryngeal release is performed to allow inferior distraction of the larynx and upper trachea.
Figure 35.6 Anchoring endotracheal tube. Before the orotracheal tube is drawn back, a red rubber catheter is attached to its tip with a suture (A). The catheter is drawn into the endotracheal tube and the suture is tied (B). This facilitates reintubation of the trachea after anastomotic sutures are placed.
Figure 35.7 Stay sutures. 2-0 vicryl stay sutures are used to facilitate dissection and to reduce tension on anastomotic sutures. They are placed around a ring of cartilage in the midlateral wall (A). Proximal sutures may have to be placed in the midlateral aspect of the cricoid cartilage (B).
When TRR is performed for a neoplasm, frozen-section analysis is used to confirm that the margins of the remaining trachea are free of disease. Microscopic positive margins may have to be accepted if additional resection would lead to unacceptable anastomotic tension. Cervicomediastinal nodal dissection is avoided as it would lead to tracheal devascularization.
Figure 35.8 Cervical flexion. Anastomotic sutures have been placed (A). The head is picked up to bring the chin down toward the sternum. The stay sutures are crossed and brought together to assess the degree of tension (B).
Figure 35.9 Tracheal anastomosis. The anastomosis starts with a 4-0 vicryl suture placed in the posterior midline membranous wall, with the suture ends on the outside (A). Subsequent sutures are placed in front of the previously placed suture (B).
The first anastomotic suture is placed in the posterior midline of the membranous wall (Fig. 35.9). It is passed from outside into the lumen on one end and then inside outside on the other end of the trachea. It is left untied, but snapped and clipped to the drapes. Additional posterior anastomotic sutures are placed sequentially, taking care that each suture is anterior to the previously placed sutures and clipped to the drapes in order (Fig. 35.10). The sutures are placed 3 to 4 mm from the cut edge, and 3 to 4 mm apart. The last posterior suture is placed just short of the previously placed stay suture. The process is repeated on the other side, completing placement of the posterior anastomotic sutures. Anterior anastomotic sutures are next placed and are clipped to the drapes anteriorly, again taking care to maintain their order. Temporary removal of the endotracheal tube and apnea are used to facilitate placement of sutures.
Before tying the anastomotic sutures, the orotracheal tube is passed carefully into the distal trachea, taking care not to gather up sutures. The anesthesiologist flexes the neck by picking up the head and supports it with several blankets. The bag beneath the shoulders is deflated. The stay sutures are brought together, tied, and reclamped. The anterior anastomotic sutures are tied first (Fig. 35.11). The posterior anastomotic sutures are then tied in the reverse order of placement, proceeding anterior to posterior. The integrity of the anastomosis is verified by performing a leak test with airway pressures of 30 cm H2O. A myoplasty with a strap muscle is performed to buttress the anastomosis.
Figure 35.10 Organizing anastomotic sutures. The sutures are not tied until they are all placed. Instead, each suture is placed, snapped, and clipped to the drapes in order.
Figure 35.11 Anastomosis. Once all sutures are placed (A), the bag beneath the shoulders is deflated and the neck is flexed. The stay sutures are tied, but not cut. The anterior anastomotic sutures are tied and cut. The posterior anastomotic sutures are then tied in reverse order of placement, proceeding from anterior to posterior (B).
A small flat Jackson-Pratt drain is left in the subplatysmal or pretracheal space and brought out to one side of the incision. The platysma and skin are reapproximated. With the drapes removed, cervical flexion is confirmed, and a “guardian” no.2 suture is placed from the submental crease to the presternal skin to prevent inadvertent neck extension (Fig. 35.12). It is important not to overflex the neck, as spinal cord insufficiency is a rare but known complication. The patient is extubated in the operating room.
Figure 35.12 Guardian stitch. After the neck is closed and prior to extubation, a heavy no. 2 suture is placed to remind the patient to maintain neck flexion. The stitch is passed from the submental crease to the presternal skin.
POSTOPERATIVE MANAGEMENT
The patient is initially admitted to the intensive care unit for the first postoperative night. Oral ingestion is limited and nausea and reflux are aggressively managed, to prevent aspiration. The cervical drain may be removed on postoperative day 3 or 4 if drainage is minimal and simple. If the anastomosis is healing well at bronchoscopic examination on postoperative day 7, the chin suture is cut. The patient may be discharged the following day. The patient must avoid significant neck extension or rotation for 3 additional weeks.
Complications
While anastomotic complications after TRR are relatively infrequent, they can cause significant morbidity. Complications include anastomotic granulation, restenosis, and most disastrously separation or dehiscence. Anastomotic granulation was historically related to suture material used and has been virtually eliminated with the use of vicryl suture. It may also develop as a consequence of a tiny separation in the anastomosis. Gentle bronchoscopic debridement of granulation may be all that is necessary. A late complication of a partial separation and granulation is restenosis, as a thick scar develops.
A more significant anastomotic dehiscence leads to cervical emphysema, wound infection, and on occasion respiratory insufficiency. Securing the airway remains the first priority. Exploration is performed to determine whether the anastomosis can be salvaged or if a surgical airway is necessary. An extreme presentation of anastomotic dehiscence is a tracheoinnominate fistula, which is often fatal. Fortunately, severe anastomotic dehiscence is quite rare in properly selected patients undergoing TRR at experienced centers.
RESULTS
Our center reported the largest single series of patients undergoing TRR for PITS, in which 471 out of 503 (94%) patients had good or satisfactory results (including freedom from tracheal appliance). The mortality rate was 2.4%. A subsequent report identified prior tracheal surgery, diabetes, lengthy resection (>4 cm), age less than 17 years, and need for preoperative tracheostomy as risk factors for anastomotic complications.
Five-year survival after tracheal resection for primary carcinoma was 52% in patients with adenoid cystic carcinoma and 39% in patients with squamous cell carcinoma, in our experience. Long-term survival was associated with complete resection, negative airway margins, and adenoid cystic histology.
CONCLUSIONS
TRR effectively relieves clinically significant tracheal obstruction with acceptable morbidity and minimal risk of mortality in well-selected patients. Both primary and secondary neoplasms of the trachea may be either cured or more effectively palliated by performing tracheal resection and reconstruction.
Recommended References and Readings
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