In most situations, the patient is placed supine with the neck hyperextended and a deflatable shoulder bag in place. Arms may be tucked in or abducted. If abducted, 45 degrees is preferable so that the surgeon can stand above or below the arm.
The surgery always should begin with a full endoscopic assessment, including assessment of vocal cord function and measurement of the length of the lesion. The choice of incision and type of operation depend predominantly on the level and length of the lesion.
Orotracheal intubation is the usual manner of airway control, with dilation as needed to accommodate the usually small (6 mm or so) endotracheal tube. If the stenosis is high grade and cannot be dilated, there is usually a tracheostomy or T-tube present. The existing tube is removed, and an armored, cuffed endotracheal tube is inserted into the stoma and prepped into the field. This tube can be replaced later by a sterile tube and anesthesia tubing, once draping is complete.
Upper and midtracheal lesions can be approached via a low-collar incision, occasionally with the addition of a partial sternal split (Fig. 57-3). For lengthy lesions, the original incision should be extended. There are a number of possibilities, including a full median sternotomy, unilateral extension of a partial or full sternotomy into a fourth interspace thoracotomy, or a bilateral thoracosternotomy (clamshell) incision. If the lesion is complicated enough to require intrathoracic mobilization, we favor the clamshell incision to permit bilateral hilar release as well as mobilization of the inferior pulmonary ligaments. This approach, that is, neck incision plus clamshell, permits management of all except low tracheal and carinal lesions, which are best handled through a right posterolateral thoracotomy from the start. The transpericardial approach for a carinal resection, however, is quite feasible via a clamshell or median sternotomy.
Upper and midtracheal lesions can be approached via a low-collar incision, occasionally with the addition of a partial sternal split.
The neck incision is similar to that used for thyroidectomy but shorter because the lateral and superior dissection is less extensive. If there is a stoma, this should be circumscribed. Subplatysmal flaps are raised to expose the trachea from the level of the lower thyroid cartilage to the sternal notch. Strap muscles are separated in the midline and retracted. If both stoma and endotracheal tube are present, all dissection is begun distant to this site, in a region with recognizable planes. The surgery then proceeds toward this usually inflamed and fibrotic area, and all pretracheal and peristomal tissue is excised. The thyroid isthmus is divided in the midline, and the edges are suture-ligated. The thyroid lobes then are dissected away from the trachea, taking care that sharp dissection is used in the plane immediately next to the trachea to avoid injury to the recurrent laryngeal nerves. Since these nerves travel upward in the tracheoesophageal groove before they enter the larynx at its posterolateral aspect, extreme care should be taken in this area, and dissection should stop short of their usual location. In general, the nerves should not be deliberately exposed as long as one follows the technical principle of maintaining the dissection close to the trachea.
Once the trachea is exposed, the lesion is evaluated carefully. Mobilization of the anterior trachea is done by blunt finger dissection in the pretracheal space, similar to the technique used for cervical mediastinoscopy. Careful dissection in the tracheoesophageal groove then is accomplished to separate the trachea from the esophagus, and again, the finger is used to bluntly dissect the posterior tracheal plane downward into the mediastinum. It is of vital importance in tracheal surgery to limit these dissections to the anterior and posterior planes to preserve the lateral tracheal connective tissue because the tenuous blood supply to the trachea occurs mostly via laterally located branches (Fig. 57-4).1 Circumferential dissection of the trachea should be done only at the level of the lesion and 1 to 2 mm beyond the planned margins of resection. These maneuvers should mobilize the trachea adequately so that it can be evaluated for extent of the lesion. Both external and endoscopic assessments should be done. The flexible bronchoscope is inserted through a partially withdrawn endotracheal tube, and using a small needle inserted through the anterior tracheal wall, the proximal and distal extents of the lesion are identified. All gross evidence of external and internal abnormalities should be resected. If a stoma is present, the bronchoscope still should be passed from above through the glottis, and the endotracheal tube in the field should be removed as needed for accurate evaluation. If possible, as it usually is, the stoma is resected along with the lesion.
Dissection of the trachea should be limited to the anterior and posterior planes to preserve the lateral tracheal connective tissue because the blood supply to the trachea occurs mostly via laterally located branches.
At this stage of the operation, the surgeon must decide whether to pursue a partial sternal split, a full sternotomy, or a clamshell incision to complete the resection and reconstruction. A partial sternotomy carried just below the sternal angle is sufficient for most benign disease, even for lesions in the lower trachea (Fig. 57-5). Lesions at or just above the carina will require a larger or different incision. A vertical skin incision from the midpoint of the collar incision to just below the sternal angle should suffice for the partial sternotomy.
A partial sternotomy is carried out just below the sternal angle and is sufficient for most benign disease, even for lesions in the lower trachea.
The anterolateral or cartilaginous trachea inferior to the lesion is opened with a knife, which is held at a right angle to the tracheal surface. Although not necessary, it is best to cut at an intercartilaginous level. The membranous trachea is not yet severed so as to prevent retraction of the distal end. An armored endotracheal tube then is inserted into the distal trachea, and the previous orotracheal tube is withdrawn to the level of the glottis but not removed. It is helpful to place a heavy silk tie through the tip of the endotracheal tube before this is withdrawn to facilitate its removal later in the operation. If a stoma is present, the endotracheal tube is simply transferred to the distal trachea. The interior lumen of the trachea is inspected and confirmed to be grossly free of disease at the cut margin. The proximal margin then is identified in a similar fashion, and the cartilaginous trachea again is opened above this margin. The interior lumen is inspected once more to ensure freedom from gross disease. In this manner, if gross disease is identified at the margin proximally or distally, additional rings can be resected, always from the cartilaginous side only, and sparing the membranous portion to avoid retraction (Fig. 57-6).
Traction sutures are placed. The membranous trachea is not severed until all the affected rings have been excised to prevent retraction of the distal end.
Once the final levels are determined, a traction suture is placed at each midlateral position of the distal trachea. We usually use braided polyglactin 910 (Vicryl) 2-0 and apply these sutures around the second cartilage ring away from the cut edge. The needles are left in place. In the case of very proximal lesions, traction sutures may be placed in the midlateral cricoid, but preferably not through and through. The membranous trachea then is sharply transected. The same procedure is followed for the proximal end. Margins may be sent for frozen section as necessary for neoplastic disease.
When the posterior surface of the trachea is difficult to bluntly dissect from the esophagus, the distal end should be completely transected early on and the proximal trachea lifted for better visualization and dissection.
The adequacy of mobilization is assessed by deflating the shoulder bag and asking the anesthetist to flex the neck. Neck flexion is the most important maneuver for release of tension. The traction sutures are used to pull the tracheal edges together and estimate the degree of tension (Fig. 57-7). There is almost invariably some tension on the anastomosis, but it should not be excessive. Unfortunately, save for experience and surgical judgment, there is no rule of thumb for determining how much tension is acceptable. If additional mobilization is needed, the shoulder bag is reinflated and additional anterior and posterior dissection is performed. If the level of tension is still unacceptable after maximal dissection, additional release maneuvers can be performed. These are fully described below.
After resection, the traction sutures are used to pull the tracheal edges together and estimate the degree of tension.
The tracheal anastomosis can be done in a variety of ways, but one unvarying current standard is that the sutures have to be either absorbable sutures of high tensile strength such as Vicryl or polydioxanone (PDS) or nonabsorbable sutures of a nonreactive material such as stainless steel. The knots usually are placed outside the anastomosis, but with stainless steel, these also can be tied inside the lumen without fear of excessive granulation tissue formation. Steel has the advantage of forming a secure knot after only two throws if the knot is square. Hence the size of the intraluminal knot with fine wire is very small.2
Our favored technique is as follows: With the neck extended once more, we choose either a running 4-0 PDS or an interrupted suture for the membranous trachea. Our experience with lung transplantation has made us confident that as long as there is little tension on the anastomosis, as with short-segment stenoses, the continuous PDS technique is safe and easy to use. We have yet to encounter a problem with this method in our selected patients (Fig. 57-8). The first stitches are 3-0 Vicryl anchoring sutures placed through the cartilaginous trachea of both ends, just anterior to the cartilaginomembranous junction on either side. The endotracheal tube is easily retracted to one side while the membranous tracheal stitches are placed, and exposure is always adequate. The 4-0 PDS stitch then is begun on the side away from the surgeon. The first bite goes through the cartilaginous trachea very near the anchoring stitch and continues in a running fashion, with intervals of 3 to 4 mm, taking 3- to 4-mm deep bites on either side. On completion of the posterior wall, the shoulder bag is deflated and the neck flexed to approximate the tracheal ends. The endotracheal tube in the field is removed, and the oral tube is advanced through the anastomosis. The tracheal edges are pulled together using the previously placed 2-0 Vicryl. The 3-0 Vicryl anchoring stitches are tied without tension using only three throws. The slack in the PDS is taken up with a nerve hook, and the ends of the PDS stitch are tied to one of the Vicryl anchoring stitch ends. Alternatively, if there is more than minimal tension, instead of PDS, 4-0 Vicryl sutures are placed in simple interrupted manner. The knots are placed outside, starting from the posterior midline and proceeding to either side until just before the laterally placed traction sutures. The long strands of Vicryl are clamped with a hemostat, and clipping them to the drapes preserves order. Alternatively, the hemostats themselves can be hung on a Kelly clamp. The head drape should not be used for clipping the sutures because these will be displaced later when the neck is flexed. After placing the interrupted stitches, flexing the neck, and switching the endotracheal tubes, the previously placed midlateral 2-0 Vicryl traction suture is used to pull the tracheal edges together. They can even be tied together to free up an assistant. The proximal traction suture is removed, and the distal Vicryl is stitched through the proximal ends and tied. The membranous tracheal sutures then are tied without tension beginning at the posterior midline and proceeding laterally. If the difficulty of dissection is such that knots can only be placed inside the lumen, the fine stainless steel wire sutures are easy to place, albeit tying the knots requires some finesse.
A. 3-0 Vicryl anchoring sutures are placed through the cartilaginous trachea of both ends. The posterior wall is sutured first. The first bite goes through the cartilaginous trachea and continues in running fashion at intervals of 3 to 4 mm. B. On completion of the posterior wall, the tracheal edges are pulled together using the previously placed 2-0 Vicryl, and the 3-0 Vicryl anchoring stitches are tied without tension using only three throws. C. The ends of the PDS stitch are tied to one of the Vicryl anchoring stitch ends. Alternatively, if there is more than minimal tension, instead of PDS, 4-0 Vicryl sutures are placed in simple interrupted manner. The knots are placed outside, starting from the posterior midline and proceeding to either side until just before the laterally placed traction sutures. D. Regardless of the technique used for the posterior wall, the anterior sutures of interrupted 4-0 Vicryl now can be placed without difficulty.
Regardless of the technique used for the posterior wall, the anterior sutures of interrupted 4-0 Vicryl now can be placed without difficulty. Occasionally, there is an overlap of the cartilaginous tracheal edges, but this is quite acceptable. The anastomosis then is tested by deflating the endotracheal tube cuff and administering positive pressure. The wound is irrigated, and a small suction drain is left in place at the pretracheal plane (but away from the anastomosis). If a partial sternotomy incision was used, an additional drain is left in the substernal space, and the sternum is approximated with stainless steel wires. The rest of the closure is performed as with any neck surgery.
A stout suture (at least Prolene 2) is placed through the chin at the inferior mandibular angle and then at the anterior chest just above the sternal angle. This is used not to achieve neck flexion but to avoid extension, and is just a reminder stitch.
These additional techniques are employed sparingly, and only when the tracheal ends cannot be approximated with acceptable tension. For upper to midtracheal lesions approached from a neck incision with or without a partial sternotomy, a Montgomery suprahyoid release is first done.3 Usually, a second transverse neck incision is made directly over the hyoid bone. The strap muscles (i.e., mylohyoid, geniohyoid, and genioglossus) overlying the hyoid are cut horizontally until the bone itself is exposed. The superior edge is also cauterized free of muscular attachments beginning from the midline and proceeding laterally until the lesser cornua is reached. This is transected with heavy scissors, and just lateral to the lesser cornua, the hyoid bone is cut, taking care not to injure the digastric sling, which is at the lateral hyoid. The suprahyoid membrane should not be exposed, and the knife is used to make a careful transverse incision over the length of the hyoid bone between the lesser cornuae. The preepiglottic space is now opened, and the hyoid body can drop to allow for at least 1 cm of release.
Mobilization of the inferior pulmonary ligament on one or both sides, as well as an intrapericardial release, is the next maneuver to consider for lower to midtracheal lesions. The technique is variable, based on the exposure obtained. If a clamshell incision is used, both inferior pulmonary ligaments can be mobilized, and both hila can be subjected to intrapericardial release (Fig. 57-9). On the right side, the pulmonary veins are exposed and the pericardium is opened just anterior to the superior pulmonary vein (Fig. 57-10). Once the pericardium is entered, a circumferential opening is created with scissors, encircling both pulmonary veins, with a release felt on completing the opening. The scissors are used to cut the frenulum, which attaches the inferior vena cava to the pericardium. The superior aspect of the pericardial incision is then carried upward anterior to the pulmonary artery and right mainstem bronchus to expose these structures and isolate them. On the left side, the pulmonary veins cannot be circumscribed, but a pericardial incision is created in a U shape with the two pulmonary veins and the left main pulmonary artery within the U. At least 2 cm of length can be achieved with these maneuvers.
With the clamshell incision, both inferior pulmonary ligaments can be mobilized and both hila subjected to intrapericardial release.
A. On the right, the pulmonary veins are exposed and the pericardium is opened just anterior to the superior pulmonary vein. B. A circumferential opening is created with scissors, encircling both pulmonary veins. C. Scissors are used to cut the frenulum.