Basil S. Nasir and Moishe Liberman
INDICATIONS/CONTRAINDICATIONS
Occasionally, during tracheal resection, a length of trachea needs to be resected such that an anastomosis between the ends of the trachea cannot be completed without undue tension. The length of trachea that can be resected for such a situation to arise varies for each individual. This depends on factors such as age, body habitus, tracheal length, posture, and previous tracheal surgery. The technique for tracheal resection is described in Chapter 36 of this book. By utilizing cervicomediastinal mobilization and mild neck flexion up to 30 degrees one is typically able to resect 4 to 6 cm of trachea, or approximately seven tracheal rings. In most situations, this is sufficient for a satisfactory anastomotic result; however, in certain situations, such as resection for malignant tracheal tumors or complex stenosis; a longer resection may be necessary. In these circumstances, multiple maneuvers can be used to allow an additional length of trachea to be released and still permit an anastomosis without tension. Options include suprahyoid release, right hilar mobilization, pericardial release, and in extreme situations transplantation of the left mainstem bronchus.
The suprahyoid release was first described by Montgomery in 1974. It is most useful for resection of the upper and middle trachea. These procedures are typically attempted through a cervical or cervicomediastinal approach. The suprahyoid release contributes very little to resection of the lower trachea or supracarinal region. The additional length that is gained from a suprahyoid release is 1 to 2 cm.
Contraindications
There is no specific contraindication to suprahyoid release in patients who are otherwise candidates for tracheal resection. The deterioration of aspiration postoperatively is a possibility. Patients who undergo surgery for postintubation stenosis, especially elderly patients, typically have an element of subclinical aspiration. The evolution of aspiration in patients with postoperative aspiration is multifactorial, and the addition of a suprahyoid release may be additive but is certainly not a sole contributor. Certainly, a laryngeal nerve injury poses much more important problems. Therefore, the presence of mild aspiration is not a contraindication. Assessment with a barium esophogram and with a speech pathologist may reveal severe aspiration. If this cannot be improved before surgery, then an external breathing device such as permanent tracheostomy or T-tube may be a better option in these patients.
PREOPERATIVE PLANNING
The preoperative evaluation is the same as that for patients undergoing evaluation for tracheal resection. The evaluation is geared toward identifying the etiology of the stenosis and then identifying the level and amount of trachea that is involved and will need to be subsequently resected. A history and physical examination, radiographic imaging of the airway, and bronchoscopy are essential in the preoperative evaluation. Imaging of the trachea can include radiographs of the neck and chest and computed tomography (CT). CT is a simple test that can show the entire airway, mediastinum, and lung fields. It is absolute in patients with malignant disease. The addition of intravenous contrast also helps visualize clearly the great vessels within the mediastinum. High-resolution CT scan with three-dimensional reconstruction is helpful in providing a road map for surgical planning prior to bronchoscopy.
Bronchoscopy is indispensable in the preoperative evaluation. Much information can be gained from awake bronchoscopy under local anesthesia and sedation with flexion and extension of the neck under bronchoscopic visualization. In patients with severe stenosis, the initial evaluation is with rigid bronchoscopy inserted just past the vocal cords and placed above the stenosis or tumor. A very detailed evaluation of the dimension of the lesion and the length of trachea that needs to be resected is made. Important measurements include the distance from the vocal cords to the top of the lesion, distal aspect of the lesion, and the carina. A biopsy can be performed at this point if necessary. Barium esophogram and evaluation by a speech pathologist is reserved for patients with swallowing difficulties or aspiration.
SURGERY
Positioning
The patient is positioned supine on the table with an inflatable bag beneath the shoulders. The neck is positioned in extension to allow it to be in a horizontal plane in line with the sternum. This delivers the trachea into the neck and allows near entire exposure through a cervicomediastinal approach. The arms may be tucked onto the patient’s sides. If access to one or both arms is desired for invasive arterial monitoring or venous access, than they may be abducted on additional arm boards. If entry to either pleural space is anticipated (the right most commonly), then a rolled support is placed longitudinally beneath the upper back, parallel to the spine and just to the right of the midline. The right shoulder is partially abducted and the elbow is partially flexed. This elevates the right thorax slightly and exposes it all the way to the posterior axillary line, making an extension via right anterior thoracotomy much more feasible.
Anesthetic Considerations
Planning for anesthesia is a key feature of airway surgery. This should be undertaken in collaboration between the anesthesiologist and the surgeon. The presence of tracheostomy simplifies the anesthetic plan substantially. However, if no tracheostomy is present, then the plan for induction and control of the airway is dependent on the degree of stenosis.
In patients with critical airway stenosis and an airway diameter of <6 mm, the induction should be carried out with a mild inhaled anesthetic, such as halothane or enflurane. The trachea is intubated with a rigid tracheoscope, placed just past the vocal cords. Jet ventilation could be initiated at this point if needed. The stenosis is gently dilated under direct vision and a small endotracheal tube is placed transorally and navigated through the stenosis into the distal airway. At this point, with the distal airway intubated, one can switch to intravenous maintenance anesthesia.
In patients without critical stenosis, induction with intravenous anesthesia can be undertaken and intubation of the airway with a small endotracheal tube in the usual fashion. Maintenance with total intravenous anesthesia, for example propofol, lends itself well to airway surgery. Details of anesthetic management during airway manipulation and transection will be discussed in Chapter 36 of this book on tracheal resection.
Incision
For cervical approaches to the trachea, a low transverse collar incision, typically incorporating the previous tracheostomy site is undertaken. If a cervicomediastinal approach is necessary, a vertical extension down the midline to a distance of 2 cm below the angle of Louis is added and an upper sternal split is done. Through such incisions, access to the suprahyoid region is cumbersome and quite difficult.
If a suprahyoid release is required, we prefer an additional horizontal incision, which is placed directly over the hyoid bone. The incision need not be long; 4 cm is enough to perform the release maneuver. This is shown in Figure 31.1.
Technique
Once the incision is made, the dissection is carried down through the subcutaneous fat and platysma all the way down to the hyoid bone. The cephalad surface of the hyoid bone is identified and dissected first. Figure 31.2 shows the hyoid bone with all its muscular attachments before commencing the release. The tendon of the stylohyoid muscles are incised bilaterally. Care is taken to preserve the tendon of the digastric muscles. All the muscles attached to the hyoid bone, between the two tendons of the digastric muscle are incised. These are the mylohyoid, geniohyoid, and genioglossus muscles from superficial to deep. We prefer using electrocautery to transect the muscle. Next, using heavy Mayo scissors, the lesser cornu of the hyoid, along with the chondroglossus muscle are transected. The hyoid bone is subsequently transected bilaterally just anterior to attachments of the digastric muscle, and lateral to the lesser cornu. This step is shown in Figure 31.3. With this, the hyoid bone is completely released (Fig. 31.4).
Figure 31.1 Location of incisions for tracheal resection (red) and a separate incision for the suprahyoid release (blue).
Figure 31.2 This shows the muscles attached to the hyoid bone. The dashed red line depicts the location of the incision to commence the suprahyoid release. Of note, the left strap muscles have been cut for demonstration of the underlying thyroid cartilage.
The incision is typically closed in two layers; a continuous 3-0 absorbable suture in the subcutaneous tissue followed by a subcuticular running continuous layer with 4-0 absorbable suture. The closure should be undertaken before completing the tracheal resection and reconstruction as this area will not be accessible after neck flexion.
Figure 31.3 Shows the result after incising the mylohyoid, geniohyoid, and genioglossus. The next step is to incise the lesser cornu of the hyoid bilaterally along the red dashed lines. Following that, the hypid is transected medial to the attachment of the digastric muscle bilaterally (along the dashed blue lines).
Figure 31.4 The end result after incision of the mylohyoid, geniohyoid, and genioglossus; excision of the lesser cornu; and transection of the hyoid bone laterally.
COMPLICATIONS
A suprahyoid release does not increase the morbidity of the associated procedure. Therefore, complications are similar to ones encountered after complex tracheal resections and will be addressed in Chapter 36.
Use of a suprahyoid release may have an additive effect on problems associated with swallowing and possibly aspiration. In large published experiences, the use of a suprahyoid release does not seem to be a sole contributor to swallowing difficulties in the postoperative period. If such problems are encountered, then supportive measures are employed and evaluation by a speech pathologist is valuable. A substantial proportion will improve with time in the immediate postoperative setting. In severe cases, a gastrostomy tube may be needed for enteral feeding.
In the largest experience of tracheal resection and primary reconstruction including 503 patients that was published in 1995 (Grillo et al.), 46 patients underwent a laryngeal release maneuver. The incidence of laryngeal dysfunction (defined as aspiration or vocal cord dysfunction) was 5%. Of those 25 patients, 14 patients had resolution of the dysfunction with time. The remaining 11 patients required either tracheostomy or T-tube. Two patients required gastrostomy tube for feeding due to severe aspiration.
Recommended References and Readings
Grillo HC. Surgery of the Trachea and Bronchi. Hamilton: BC Decker Inc; 2004.
Grillo HC, Donahue DM, Mathisen DJ, et al. Postintubation tracheal stenosis: Treatment and results. J Thorac Cardiovasc Surg. 1995; 109:486–493.
Liberman M, Mathisen DJ. Surgical anatomy of the trachea and techniques of resection and reconstruction. Shields TW, Locicero J, Reed CEet al. General Thoracic Surgery. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:955–965.
Montgomery WW. Suprahyoid release for tracheal anastomosis. Arch Otolaryngol. 1974;99:255–260.