Eric M. Genden
INTRODUCTION
The history of tracheal reconstruction dates back more than 200 years. While many initially viewed the trachea as merely an airway conduit that could be replaced by an alloplastic tube, investigators and surgeons have gained a greater respect for the complex biology of the airway. The tracheal airway plays a critical role in mucociliary transport, airway hygiene, and antigen processing. Ideally, reconstructive techniques should strive to maintain these important functions.
Tracheal airway defects can be classified into three categories: Defects less than 4 cm, defects between 4 and 6 cm, and defects greater than 6 cm in length. Defects less than 4 cm are usually amenable to primary end-to-end anastomosis. Defects between 4 and 6 cm may require a multistaged reconstruction, and defects greater than 6 cm continue to represent a reconstructive dilemma; although a variety of techniques have been used to manage the latter group including allograft reconstruction, alloplastic reconstitution, and tracheal transplantation, none has proven effective.
HISTORY
A careful preoperative history and physical examination are essential. I feel that a detailed history is important in trying to understand the nature of the tracheal problem particularly a history of prior surgery, infection, and compromised wound healing. The underlying cause of the tracheal problem is important because it will help to determine the best approach to the reconstruction and often estimate the risk of restenosis. Tracheal defects may be the result of trauma, tumor resection, congenital stenosis, inhalational injury, or acquired idiopathic disease. While defects from trauma and tumor resection are often focal in nature, congenital and inhalational tracheal disease may result in more diffuse injury and therefore more extensive defects. In contrast, idiopathic disease often involves the cricoid cartilage and therefore presents a separate set of challenges. A thorough history can help to elucidate the underlying cause of the tracheal disease as well as to predict the nature of the defect and the best approach for reconstruction.
Factors of a general nature in the patient’s history include infection or adverse wound healing. Both issues can compromise the outcome and, in some cases, may result in a catastrophic complication. Patients with brittle diabetes, collagen vascular disease, or prior surgery represent the greatest challenge.
PHYSICAL EXAMINATION
The physical examination includes both preoperative and intraoperative evaluations. Preoperatively, pulmonary function studies, computed tomography (CT), and endoscopy represent the three pillars of the evaluation. The pulmonary function studies are not essential for every patient but may provide information about whether the airway obstruction is fixed or dynamic. Dynamic obstruction, such as tracheomalacia and vascular compression syndrome, is often more challenging to manage than is focal fixed obstruction. The CT scan and the endoscopic evaluations often provide information related to the length and site of the stenosis. Flexible tracheoscopy can be performed in the office to evaluate the airway and determine if an obstruction is dynamic or fixed. Unfortunately, not all patients will tolerate such an examination. The high-resolution CT scan (1-mm cuts) is a highly sensitive method used in the evaluation of the infraglottic airway, and I find that the axial, coronal, and sagittal views each offer important information (Fig. 27.1A and B). Three-dimensional reconstruction can also provide important information related to the site of the stenosis (Fig. 27.2).
FIGURE 27.1 A,B. The high-resolution CT scan (1-mm cuts) provides a sensitive method to evaluate the infraglottic airway. These images demonstrate invasion of the trachea that may not be appreciated on office endoscopy.
FIGURE 27.2 Three-dimensional reconstruction can provide important information related to the site of the stenosis.
The intraoperative endoscopy typically provides the best examination. A rigid fiberoptic endoscope provides a high-resolution evaluation of the airway that can be exceptionally helpful in determining the nature of the disease and predict the best approach to reconstruction (Fig. 27.3).
FIGURE 27.3 High-resolution endoscopy of a tracheal lesion.
INDICATIONS
The indications for primary (end-to-end) tracheal reconstruction are defects that are less than 4 cm in length. In select patients, defects that are less than 6 cm can be managed with primary end-to-end reconstruction but may require infrahyoid muscle release and/or a suprahyoid muscle release. However, these techniques impede elevation of the larynx during swallowing and may result in aspiration.
CONTRAINDICATIONS
The contraindications to primary tracheal reconstruction are patients with defects greater than 6 cm in length and patients with defects greater than 4 cm in length if there is a history of a previously failed reconstruction, external beam radiation therapy, or compromised healing. It is critical to understand that every patient is an individual and therefore each patient should be evaluated as such. Most contraindications are “relative” contraindications. The patient’s anatomy, body habitus, and personal disposition all play a role in the decision-making process concerning reconstruction.
PREOPERATIVE PLANNING
Prior to surgery, I evaluate airway resistance in all subjects. A flow-volume loop is generated by having the patient inhale deeply to total lung capacity (TLC), forcefully exhale until the lungs have been emptied to residual volume, and rapidly inhale to reach TLC. A maximal expiratory flow 50%: Maximal inspiratory flow 50% ratio is, therefore, usually less than 1. In variable extrathoracic lesions, the ratio is increased (usually >1), while in variable intrathoracic lesions, the ratio is diminished (0.2 or less). In fixed obstructions, the ratio is expected to be close to 1. This study provides an excellent method to determine diagnosis and eligibility for surgery.
SURGICAL TECHNIQUE
Primary reconstruction of the trachea can be achieved through a straight end-to-end technique or a sliding technique depending on the defect and the needs of the patient. Independent of the approach, the basic technique is similar. Prior to oral–tracheal intubation, I perform a rigid endoscopy using an apneic technique or with a ventilating bronchoscope. This provides an opportunity to reevaluate the nature of the tracheal disease and it thoroughly acquaint me with the location of the pathology. After the endoscopy, the patient is intubated orally, and the standard sterile preparation is performed. The neck is exposed through a standard collar incision. The trachea is exposed through a midline strap-splitting approach.
The trachea is isolated by dissecting along it with Metzenbaum scissors and bipolar cautery to achieve a bloodless field. Careful attention is dedicated to the recurrent laryngeal nerves, and as the dissection progresses peripherally, the soft tissue enveloping the recurrent laryngeal nerves is gently dissected off of the trachea.
Once the trachea is isolated, the cuff of the endotracheal tube is deflated and a transverse incision is made into the airway above and below the stenosis. The resection of the tracheal disease should include both the cartilaginous trachea and the membranous posterior segment.
Once the tracheal resection is complete, the distal trachea can be dissected from the esophagus and surrounding soft tissue to release and advance the airway cephalad. The mediastinal release can be achieved through careful blunt finger dissection. In short defects of the trachea, a mediastinal release may be appropriate; however, in more extensive defects, an infrahyoid and/or suprahyoid release may be required. In either case, the hyoid attachments can be cut with electrocautery at a low setting in an effort to prevent injury to the superior laryngeal nerves.
Once the tracheal release has been achieved, the anastomosis can be performed. I begin the procedure by deflating the cuff of the endotracheal tube to expose the defect in the posterior wall (Fig. 27.4A). The posterior wall of the trachea is reconstructed using 3-0 glycolide suture (Monocryl, Ethicon, Somerville, NJ). The sutures are placed interrupted with the knots directed outside of the lumen (Fig. 27.4B). Once the posterior membranous wall has been reconstructed, the remainder of the cartilage tracheal anastomosis can be completed using 2-0 polypropylene suture (Prolene suture, Ethicon, Somerville, NJ). The sutures are placed interrupted, and the knots are directed outside the lumen (Fig. 27.4C).
FIGURE 27.4 A. The tracheal defect resulting from resection of the airway. B. Reconstruction of the membranous posterior tracheal wall with absorbable sutures. C. Interrupted nonabsorbable sutures used to reconstruct the anterior tracheal wall.
I like to place a “tension-releasing suture” across the tracheal anastomosis to alleviate tension on the tracheal anastomosis. The strap muscles are closed over the trachea, and a suction drain is placed.
POSTOPERATIVE MANAGEMENT
Postoperatively, the patient is extubated in the operating room. The patient is then transferred to a monitored bed for 24 hours. I consider discharge from the hospital on postoperative day 4 or 5. Patients are instructed on open-mouth sneezing and minimal coughing.
COMPLICATIONS
Complications of airway reconstruction can range from minor infections to catastrophic anastomotic breakdown. Careful routine evaluation of the patient is important to identify complications and institute early management. Minor complications such as subcutaneous air can result in wound infection and tracheal anastomotic breakdown without early intervention. More significant complications such as wound breakdown require aggressive management that should not be delayed.
RESULTS
I have found that this technique is reliable and safe in my personal series of more than 150 such cases. Meticulous surgical technique tends to limit the risk of minor complications such as intraluminal granulation tissue and restenosis. Extubation in the operating room is helpful in identifying problems early so that the patient can be managed in a safe and monitored setting. My complication rate is less than 1%, and my restenosis rate is less than 3%.
PEARLS
• Endoscopy and CT scan are essential aspects of the preoperative evaluation.
• Endoscopy performed in the operating room prior to surgery is helpful in evaluating the pathology and predicting the defect.
• Meticulous surgical technique will help to prevent granulation tissue in the tracheal lumen.
• When the tracheal ends are brought together, it is important to oppose the ends and not prolapse them.
PITFALLS
• Early recognition of an anastomotic leak can be made at the time of extubation. It can also be managed immediately before subcutaneous air and infection ensue.
• If the suture knots are placed intraluminal, granulation and restenosis are more common.
INSTRUMENTS TO HAVE AVAILABLE
• Standard head and neck surgery set
• Rigid fiberoptic endoscopy
SUGGESTED READING
de Alarcon A, Rutter MJ. Cervical slide tracheoplasty. Arch Otolaryngol Head Neck Surg 2012;138:812–816.
Delaere PR. Tracheal transplantation (Review). Curr Opin Pulm Med 2012;18:313–320.
Rich JT, Gullane PJ. Current concepts in tracheal reconstruction. Curr Opin Otolaryngol Head Neck Surg 2012;20:246–253.