Step 1
Surgical Anatomy
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Functionally, the trachea principally serves as a conduit for ventilation. Anatomically, it presents several unique features that partially account for the difficulty in its surgical management, including the following:
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Unpaired nature
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Unique structural rigidity
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Short length
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Relative lack of longitudinal elasticity
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Proximity to major cardiovascular structures
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Segmental blood supply
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The adult human trachea possesses the following anatomic features:
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Average length is 11.8 cm (range, 10-13 cm) from the infracricoid level to the top of the carinal spur.
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It has 18 to 22 cartilaginous rings.
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There are approximately two rings per centimeter.
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In an adult man, the internal diameter of the trachea measures about 2.3 cm laterally and 1.8 cm anteroposteriorly.
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Measurements vary roughly in proportion to the size of the individual; therefore, they are usually smaller in women (13-27 mm in men; 10-23 mm in women).
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The cross-sectional shape of the adult trachea is nearly elliptic.
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In infants and children the trachea is more circular.
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The trachea’s configuration may change with disease.
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The lower two thirds may be flattened in tracheomalacia or rigidly narrowed from side to side to produce a saber-sheath trachea.
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The trachea becomes almost entirely mediastinal when the neck is flexed because the cricoid cartilage drops to the level of the thoracic inlet.
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The trachea courses backward and downward at an angle from a nearly subcutaneous position at the infracricoid level to rest against the esophagus and vertebral column at the carina.
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The larynx and the origin of the esophagus are intimately related anatomically at the cricopharyngeal level.
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Below the cricoid, the posterior membranous wall of the trachea maintains a close spatial relationship to the esophagus.
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A distinct, easily separable plane between the trachea and esophagus is present below the cricoid level; however, a common blood supply is shared.
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Anteriorly, the thyroid isthmus passes over the trachea in the region of the second tracheal ring.
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The lateral lobes of the thyroid are closely applied to the trachea, and a common blood supply is shared from the branches of the inferior thyroid artery.
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Lying in the groove between trachea and esophagus are the recurrent laryngeal nerves: the left courses from beneath the arch of aorta and the right loops around subclavian artery and then approaches the groove. Therefore, the left recurrent laryngeal nerve has a longer course in proximity to the trachea than does the right.
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The recurrent nerves enter the larynx between the cricoid and thyroid cartilages just anterior to the inferior cornu of the thyroid cartilage.
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The blood supply of the human trachea is segmental, largely shared with the esophagus and derived principally from multiple branches of the inferior thyroid artery above and the bronchial arteries below.
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The arteries approach laterally, and fine branches pass anteriorly to the trachea and posteriorly to the esophagus.
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The inferior thyroid artery nourishes the upper trachea, usually through a pattern of three principal branches with fine subdivisions and extremely fine collateral vessels.
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The bronchial vessels nourish the lower trachea, carina, and mainstem bronchi.
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Occasionally, the internal mammary artery contributes to the distal blood supply.
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Excessive circumferential dissection with division of the lateral pedicles during an operative procedure can easily devascularize the trachea.
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The trachea lives in a crowded area surrounded by many important structures. Surrounding anatomy includes the following:
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The anterior pretracheal plane is made up of fibrofatty tissue, lymph nodes, and fine branches of the anterior jugular vein.
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This plane can be easily developed using blunt finger dissection through a cervical approach (similar to blunt, index-finger anterior tracheal dissection performed during mediastinoscopy).
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The innominate vein lies anteriorly, away from the trachea.
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The innominate artery crosses over the midtrachea obliquely from its point of origin on the aortic arch to the right side of the neck.
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In children, the innominate artery is higher and is encountered in the lower part of the neck.
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In some adults, the artery is unusually high and crosses the trachea at the base of the neck when slight cervical extension is present.
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Occasionally a tiny branch of this artery may be encountered stemming from the segment of the artery that crosses the trachea.
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At the level of the carina, the left main bronchus passes beneath the aortic arch and the right main bronchus beneath the azygos vein.
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The pulmonary artery lies just in front of the carina.
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On either side of the trachea lies fibrofatty tissue containing lymph node chains, and a large packet of nodes lies in the subcarinal space.
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Step 2
Preoperative Considerations
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Patient should not require mechanical ventilation.
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Pulmonary function testing should be performed for patients with pulmonary disease.
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Patient should stop smoking.
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Nutritional optimization (malnourished) or weight loss (obesity) should be recommended.
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Appropriate staging tests should be completed when dealing with malignancy.
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If mediastinoscopy is required for staging purposes, it should be completed at the time of planned resection to aid in assessing the outer airway and in creating the pretracheal plane.
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If mediastinoscopy is done during a separate operation before resection, mobility of the trachea will be compromised secondary to postoperative scarring.
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If neoadjuvant radiotherapy or prior mediastinal or cervical radiotherapy has been used, a pedicled muscle or omental flap to buttress the anastomosis should be planned to aid in anastomotic healing.
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Predictors of anastomotic complications following tracheal resections include the following:
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Diabetes
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Lengthy resection (>4 cm)
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Laryngotracheal resection
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Age 17 years or younger
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Need for tracheostomy before operation
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Steroid use
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Step 3
Operative Steps
1
Anesthesia
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The airway must be under full control at all times during reconstructive surgery of the trachea to prevent hypoxia.
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The patient preferably should breathe spontaneously during the operation and always at its conclusion so that ventilatory support is not necessary postoperatively.
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Cardiopulmonary bypass has been used for tracheal resections; however, in our experience it is almost never necessary.
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Induction is carried out slowly and gently, especially in a patient with a highly obstructed airway.
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If a benign stenosis presents an airway diameter of less than 5 mm, dilatation is performed, and an endotracheal tube (ETT) is passed beyond the lesion to prevent arrhythmia caused by CO 2 buildup during the early stages of operation.
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Occasionally a nearly obstructing tumor requires prompt bronchoscopy with a ventilating bronchoscope shortly after induction, with subsequent intubation.
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Obstructing tumor may be cored out with the rigid bronchoscope aided by biopsy forceps. Frequent monitoring of blood gases and electrocardiography are essential.
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Bronchoscopic examination should be done by the surgeon and observed by the anesthesia provider, who must deal with this airway until surgical access distal to the lesion has been obtained.
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If tracheostomy is already present, induction is simplified. The anesthesiologist can ventilate and use inhalational agents by hooking the ventilator to the tracheostomy. Cross-field ventilation is used from the outset in these patients.
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In patients who are being ventilated above the lesion, initial dissection is always done carefully to avoid increasing the degree of obstruction by excessive tissue manipulation.
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In patients with critical airway stenoses, an inhalational induction technique should be employed to preserve spontaneous ventilation.
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A slow inhalational induction is used if there is a high degree of obstruction.
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This technique is preferable to paralysis of respiration, which may necessitate the urgent establishment of an airway.
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In patients with less critical airway stenoses, total intravenous anesthesia (TIVA) techniques (the use of IV agent[s] exclusively to provide a complete anesthetic) can be used.
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This allows for prompt reversal and spontaneous breathing following resection and reconstruction.
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The goal should be extubation at the end of the procedure for all patients undergoing tracheal resection.
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The area below the obstruction is isolated first so that transection of the trachea can be performed at any point and an airway can be introduced across the operative field if the degree of obstruction increases.
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Sterile anesthesia tubing, connectors, and ETTs are available on the operative field.
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At the time of tracheal division, the orotracheal tube is pulled back or removed and a sterile, cuffed, flexible, armored ETT is inserted into the distal airway across the operative field.
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Sterile connecting tubing is passed to the anesthesiologist to allow ventilation of the patient.
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This armored tube is removed whenever necessary for suctioning or placement of sutures.
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Toward completion of the operation, the original ETT is advanced into the distal airway and the anastomotic sutures tied.
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Before having the anesthesiologist pull the ETT back into the upper airway or larynx, we tie a red rubber catheter to the end of the tube and keep this in the operative field to assist in pulling the ETT back down into the field before tying down the anastomotic sutures.
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If transthoracic resection (via right thoracotomy) is performed close to the carina, the ETT is passed into the left main bronchus and that lung alone is ventilated.
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If the partial pressure of oxygen decreases toward unsatisfactory levels, a previously isolated right main pulmonary artery is temporarily clamped to eliminate the shunt through the right lung (rarely required).
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High-frequency ventilation is a useful adjunct, especially in complex carinal reconstruction.
2
Anatomic Mobilization
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The length of trachea that can be resected safely in an individual varies widely with age, posture, body habitus, extent of disease, and prior tracheal surgery.
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Attention must be paid to the lateral blood supply during tracheal mobilization.
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Mobilization of the proximal and distal segments should occur on the anterior and posterior portion of the airway.
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Use of blunt finger dissection on the anterior portion of the trachea moving downward toward the carina (mediastinoscopy plane) allows simple, safe anterior mobilization.
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Cervical flexion, combined with hilar and pericardial mobilization plus division of the pulmonary ligament, allows lengths of 5 to 6 cm of trachea to be removed by the transthoracic approach.
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Hilar release requires sternotomy or thoracotomy.
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3
Surgical Approaches
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Lesions in the upper half of the trachea that are known to be benign are best approached cervically ( Fig. 11-1 ). If a malignant lesion is present, one must be prepared for a cervicomediastinal and, possibly, a transthoracic approach. If a postoperative temporary tracheostomy stoma is required after a difficult tracheal anastomosis, the incision must be planned so that a stoma can be made away from the incision.
