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Subglottic Tracheal Resection

  • Thomas R. Todd
    Correspondence
    Address reprint requests to Thomas R. Todd, MD, FRCSC, Univereity of Toronto, Toronto Hospital, 10EN-226,200 Elisabeth St, Toronto, Ontario, Canada M5G 2C4
    Affiliations
    From the Division of Thoracic Surgery, University of Toronto, Toronto Hospital, Toronto, Ontario, Canada
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  • F. Griffith Pearson
    Affiliations
    From the Division of Thoracic Surgery, University of Toronto, Toronto Hospital, Toronto, Ontario, Canada
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      The subglottic space refers to the portion of the airway between the vocal cords and the inferior border of the cricoid cartilage. Attention to surgical pathology in this area was overshadowed for many years by the advent of successful surgery for strictures and neoplasms in the rest of the trachea. Surgical forays into this anatomic area was restricted to trauma and the management of neoplasms, wherein the ablative procedure resulted in significant impairment in glottic function. With the introduction of compliant cuffs on endotracheal tubes, the incidence of cuff strictures after endotracheal intubation decreased significantly. In addition, there has been an increasing tendency to maintain oral or nasal endotracheal intubation for longer periods of time before reverting to tracheotomy. Although more prolonged endotracheal intubation has not been causally linked to subglottic stenosis, the latter appears to have increased in incidence over the last 15 years. Before 1974, resection of the subglottic area involved the sacrifice of the recurrent laryngeal nerves because surgeons performed standard sleeve resections of the airway even in this high position. In order to resect higher into the subglottic compartment, Dr D.P. Bryce described the resection of the anterior arch of the cricoid, sparing the posterior plate and, thus, preserving the recurrent laryngeal nerves.
      • Gerwat J
      • Bryce DP
      The management of laryngeal stenosis by resection and direct anastomosis.
      It is, however, at the level of the posterior cricoid plate that the greatest degree of scarring is noted secondary to endotracheal intubation. Because of the curvature of the endotracheal tube, it's point of maximal contact and pressure with the tracheal mucosa is the posterior cricoid plate. In order to overcome this difficulty, Dr F.G. Pearson described subperichondrial resection of the posterior plate in order to permit removal of the scar and at the same time preserve the recurrent nerves.
      • Pearson FG
      • Cooper JD
      • Nelems JM
      • et al.
      Primary tracheal anastomosis after resection of the cricoid cartilage with preservation of recurrent laryngeal nerves.
      The understanding of this technique is dependent on a thorough appreciation of the anatomy of the area.
      Before considering surgical technique, it is important to understand the alternatives to surgical therapy based on the type of stricture. Fibrous strictures in the subglottic region are either inflammatory, idiopathic, or iatrogenic. Inflammatory strictures are most commonly seen with Wegener's granulomatosis and less commonly with amyloid and collagenosis. It may respond to dilation and drug therapy, but in the later fibrous stage it will usually require resection. Idiopathic strictures occur primarily in middle-aged women
      • Grillo HC
      • Mark EJ
      • Mathisen DJ
      • et al.
      Idiopathic laryngotracheal stenosis and its management.
      and may respond to simple dilation. Its recurrence beyond two or three tracheal dilatations suggests that surgical intervention should be considered.
      • Grillo HC
      • Mark EJ
      • Mathisen DJ
      • et al.
      Idiopathic laryngotracheal stenosis and its management.
      • Maddaus MA
      • Toth JLR
      • Gullane PJ
      • et al.
      Subglottic tracheal resection and synchronous laryngeal reconstruction.
      It is the iatrogenic stricture secondary to endotracheal intubation that accounts for the majority of stenoses. This too may respond to dilatation and/or stenting in the early stages, but by the time a fibrous stricture has occurred, surgical therapy is the rule. Laser therapy has been described in the past. However it is the experience of the investigators that it offers little over simple dilation and may indeed prolong the period of inflammatory change. Certainly, it is rarely definitive therapy for fibrous subglottic strictures, which frequently are associated with chondritis and calcification of the cricoid cartilage. Under these circumstances, laser therapy cannot be expected to provide lasting improvement and indeed may increase the magnitude of the injury if there is failure to control the depth of coagulation. The use of silastic stents bears particular mention. In patients who present contraindications to surgical resection, a silastic “T” tube provides a stable airway. The upper limb of the tube is positioned above the vocal cords. In this position, the patient maintains voice and the ability to swallow without aspiration.
      • Cooper JD
      • Pearson FG
      • Patterson GA
      • et al.
      Use of silicone stents in the management of airway problems.
      In cases of acute subglottic injury, it may provide definitive therapy if positioned before the establishment of a mature scar.

      Anatomic Considerations

      The required understanding of this regional anatomy begins with the cricoid cartilage. It is the only complete cartilage in the airway and because it is in the immediate subglottic area, it encircles the narrowest portion of the trachea (Figure I). It consists of a shallow anterior arch and a thick, deep posterior plate. The superior border of the cartilage articulates with the inferior cornua of the thyroid cartilage. It is immediately posterior to this joint that the recurrent laryngeal nerves pass as they enter the airway, proceeding superiorly to innervate the muscles controlling cord function. The thickness of the posterior plate of the cricoid and this position of the recurrent nerves are the major anatomic determinants of sleeve resection of the airway at this level. Superiorally and posteriorally, the cricoid articulates with the arytenoid cartilages, which attach by its vocal processes to the posterior limb of the vocal cords. This fact defines the limit of posterior dissection and resection. Although interarytenoid scarring can be excised and patched with a tongue of tracheal mucosa (see Surgical Technique), subperichondrial resection of the posterior plate can interfere with glottic function if allowed to proceed to the upper limit of the cartilage. Fortunately, the latter is not necessary in benign disease. The cricothyroid ligament provides attachment to the thyroid cartilage superiorally and anteriorally. It is a stout structure that holds anastomotic suture material well.
      Figure thumbnail gr1
      Fig ISurgical anatomy of the subglottic region. (Reprinted.
      • Maddaus M
      • Pearson FG
      Subglottic resection.
      )
      The vagus nerve supplies the glottic and subglottic area through the superior and recurrent laryngeal nerves. The former has two branches. It's first branch, the interior laryngeal nerve is sensory to the glottis above the vocal cords. It enters the larynx near the articulation of the thyroid and hyoid cartilages at the superior thyroid cornua. As a result, it is rarely in jeopardy during subglottic resection. It is more likely to be damaged during the infrahyoid laryngeal release.
      • Dedo HH
      • Fishman NH
      Laryngeal release and sleeve resection of tracheal stenosis.
      The recurrent nerves are both motor and sensory. They innervate the intrinsic laryngeal muscles and provide sensation to the subglottic mucosa. The nerves enter the larynx posterior to the cricothyroid joint deep to the inferior pharyngeal constrictor.

      Preoperative Evaluation

      A thorough bronchoscopic assessment of the airway by the operating surgeon is essential. This permits an evaluation of vocal cord function and of concomitant laryngeal injury. The surgical plan may be altered with prior knowledge of vocal cord paralysis or laryngeal damage such as posterior interarytenoid scarring (Figure II). The latter suggests the involvement of an otolaryngologist, as well as the fact that laryngofissure and laryngeal stenting may be necessary accompaniments of the subglottic resection. The bronchoscopy also permits dilation of the airway, which will facilitate the placement of an endotracheal tube by the anesthetist. When there is inflammation and/or ulceration or granulation in the stricture, a biopsy specimen for culture is prudent. In such circumstances, the airway may not only be colonized with pathogenic bacteria, but there may be associated bacterial chondritis. A positive culture warrants preoperative and postoperative antibiotic therapy. The entire airway should be examined to rule out associated disease, which is seen particularly in Wegener's granulomatosis and collagenosis of the airway.
      Figure thumbnail gr2
      Fig IIBronchoscopic view of posterior interarytenoid scar. Note the creation of two separate lumens.
      A computed axial tomography (CAT) scan of the affected area delineates the extent of involvement of the tissues abutting the inner surface of the airway and may also delineate destruction of the cartilage when chondritis is present. When neoplasms are present, the external extent of the tumor will influence the surgical approach. A preoperative chest radiograph is particularly important because many of these patients either have or have had pulmonary sepsis that may be active, or in cases of chronic obstruction, be associated with bronchiectasis.

      Anesthetic Considerations

      Dilation of the stricture at the time of the resection facilitates intubation. We prefer an armored endotracheal tube. The anesthetist should also have available an uncuffed no. 5 or 6 endotracheal tube that may be required at the end of the procedure (see Surgical Technique). On the operative set, another armored tube no. 7 is necessary for ventilation across the surgical field when division of the airway has taker place. There are frequent periods of apnea during the placement of anastomotic sutures that will over time lead to the development of atelectasis. Because intermittent positive pressure with positive end expiratory pressure appears to reinflate areas of atelectasis and thus, prevent the onset of hypoxemia, we do not recommend using jet ventilation. During the completion of the anastomosis, intermittent ventilation with 100% oxygen permits up to 2 minutes of apnea for suture placement. The anesthetist generally requires only one ventilation system because the endotracheal tube inserted by the surgeon upon division of the airway can be passed under the drapes to the anesthetist who simply uses the same system he/she employed for the initial oral endotracheal tube.
      As far as monitoring is concerned, oximetry and end tidal carbon dioxide measurements are routine. Both are important when intermittent apnea is employed. During division of the airway, oral re-intubation is facilitated by the placement of a suture through the eye of the oral endotracheal tube by the surgeon. This permits the anesthetist to safely withdraw the oral tube with the assurance that it can be easily reinserted by traction on the suture.

      SURGICAL TECHNIQUE

      Figure thumbnail fx3
      1A collar incision suffices for uncomplicated subglottic resection. When there is extensive tracheal disease present, a median sternotomy can be added to expose the mediastinal trachea or to perform a hilar release. A subplatysmal skin flap is mobilized inferiorally to the suprastenal notch and above to the superior aspect of the thyroid cartilage. The incision can be extended superiorally when a laryngeal release is necessary. Alternatively, a second incision can be performed at the level of the hyoid cartilage. The midline is opened to the extent of the flap dissection down to the anterior wall of the trachea. The thyroid isthmus is divided. Finger dissection deep to the pretracheal fascia is performed, as undertaken for a mediastinoscopy, to permit mobilization of the distal trachea. Circumferential dissection of the trachea is performed at the level of the disease when benign strictures are present or at the margin of the process in the case of neoplasia. In the former and more common scenario case, the recurrent nerves are avoided by precise dissection on the tracheal wall medial to the thyroid gland. Electrical injury to the nerves is prevented by the use of bipolar cautery. No attempt is made to identify or isolate the recurrent nerves. (Reprinted with permission from Margot Mackay.)
      Figure thumbnail fx4
      2After the trachea has been circumferentially dissected, it is divided at the lower limit of the disease. An armored endotracheal tube is passed by the surgeon under the drapes to the anesthetist and sutured in place to prevent migration. It is then placed in the distal trachea and ventilation is commenced. Stay sutures are placed in the distal airway at the junction of the cartilaginous and membranous wall. A suture is placed in the eye of the oral tube and is withdrawn into the glottis or, in some cases, the pharynx. The suture is clamped so that the oral tube can be retrieved with traction when it is again required. (Reprinted with permission from Margot Mackay.)
      Figure thumbnail fx5
      3Removal of the anterior cricoid arch. The inferior border of the cricoid cartilage is exposed and the perichondrium incised with a knife. (A) Using a Howarth elevator (Canadian Microsurgical LTD, Burlington, Ontario, Canada), the perichondrium is freed from the underlying cartilage. This preserves a stout layer of healthy tissue for the anterior wall of the anastomosis while permitting excision of the anterior arch and the deeper diseased perichondrium and mucosa (B-C). Excision of the lateral elements of the arch is frequently accomplished with fine rongeurs (D). (Figure A reprinted with permission from Margot Mackay; Figures B, C, and D reprinted.
      • Maddaus M
      • Pearson FG
      Subglottic resection.
      )
      Figure thumbnail fx6
      4After tracheal division, proximal posterior dissection is facilitated by grasping the trachea at the junction of cartilage and membranous trachea on both sides and retracting laterally and superiorally as shown. This stretches the posterior wall and delineates the plane between trachea and esophagus (A). The posterior dissection is carried up to the inferior margin of the posterior plate of the cricoid. The posterior perichondrium is incised with a knife and an elevator is employed to dissect the anterior perichondrium and mucosa off of the underlying posterior plate (B). This dissection extends superiorally to the limit of the mucosal abnormality. At this point, the entire stricture can be resected. (Reprinted with permission from Margot Mackay.)
      Figure thumbnail fx7
      5The posterior cricoid cartilage is then excised with a rongeur, thus preserving a thin rim of cartilage posteriorally that provides protection for the recurrent nerves.
      Figure thumbnail fx8
      6The distal trachea and the subglottic aperture are discrepant in size, with the distal end possessing a much larger diameter. The anastomosis is made simpler by plicating the distal trachea with a suture or sutures that approximate the ends of the tracheal rings (A). The posterior anastomotic sutures are of no. 35 wire. Two square knots are applied and the suture is cut flush on the knot. This material is nonreactive and permits a knot on the inside of the airway without granulation formation. The lateral and anterior margins of the anastomosis are placed either into the perichondrium or the thyroid cartilage itself. Interrupted Vicryl 3-0 sutures (Ethicon, Inc, Somerville, NJ) are used (B). (Reprinted with permission from Margot Mackay.)
      Figure thumbnail fx9
      7(A-B) If the anastomosis is close to the vocal cords or there has been a concomitant laryngofissure (see ) a silastic stent may be used to stent the airway. Under such circumstances the upper end of the stent will be positioned above the vocal cords. A stent placed below the cords will place unnecessary pressure on the cords, leading to edema ulceration and further obstruction. (Reprinted with permission from Margot Mackay.)
      Figure thumbnail fx10a
      8When there is associated damage to the larynx it must be dealt with at the time of subglottic resection. The thyroid cartilage is divided in the midline after the dissection noted previously is completed (A). This permits full exposure of the vocal cords and arytenoid cartilages. The usual laryngeal pathology is a posterior interarytenoid scar. This is excised, creating a posterior mucosal defect (B). The latter is covered with a tongue of tracheal epithelium constructed from the distal resection margin by the removal of one or two rings with the preservation of the membranous airway at that level (C). The anastomosis is similar to the above. At this level, the knots on the posterior row of sutures must be on the inside and the no. 35 wire suture is a great advantage (D). This high anastomosis demands the placement of a stent, either a silastic “T” tube or a laryngeal mold, accompanied by a distal tracheotomy. We prefer the “T” tube because it can be removed without a surgical procedure and preserves the patient's ability to speak. (Reprinted with permission from Margot Mackay.)
      Figure thumbnail fx10b
      8When there is associated damage to the larynx it must be dealt with at the time of subglottic resection. The thyroid cartilage is divided in the midline after the dissection noted previously is completed (A). This permits full exposure of the vocal cords and arytenoid cartilages. The usual laryngeal pathology is a posterior interarytenoid scar. This is excised, creating a posterior mucosal defect (B). The latter is covered with a tongue of tracheal epithelium constructed from the distal resection margin by the removal of one or two rings with the preservation of the membranous airway at that level (C). The anastomosis is similar to the above. At this level, the knots on the posterior row of sutures must be on the inside and the no. 35 wire suture is a great advantage (D). This high anastomosis demands the placement of a stent, either a silastic “T” tube or a laryngeal mold, accompanied by a distal tracheotomy. We prefer the “T” tube because it can be removed without a surgical procedure and preserves the patient's ability to speak. (Reprinted with permission from Margot Mackay.)

      Postoperative Care

      We attempt to have the patient breathing spontaneously at the end of the procedure to avoid the need for ventilatory support. If it is anticipated that spontaneous ventilation will not be possible for awhile then the following is advisable:
      • 1.
        In the absence of a stent or a tracheotomy, an uncuffed no. 6 endotracheal tube is placed nasally in the airway. The nasal position is more comfortable than the oral route and is more reliably secured. It can be left in place for several days with the patient breathing spontaneously, should there be significant postoperative swelling in the glottis or the anastomosis. It can also be used for ventilatory support. Often it obturates the airway, but even in the presence of a leak in the tube, ventilation is adequate. It is preferable to the use of a large cuffed tube, which may only add to airway damage.
      • 2.
        If a “T” tube is in place, ventilation can be provided by one of two routes. First, one can ventilate through the horizontal limb of the “T” tube. If the leak out of the proximal limb is too large, it can be occluded with a bronchus blocker inserted orally through the larynx. The blocker is secured by a suture tied about it's end, brought out through the horizontal limb, and held in place by the cork of the tube or a hemostat. Second, one can insert a small oral endotracheal tube into the upper limb of the “T” tube. Again it is held in place by a suture tied into it's eye and brought out through the horizontal limb in the same fashion as noted for the bronchus blocker.
      If the patient experiences airway obstruction in the early postoperative period, it may be alleviated with the inhalation of heliox (70% helium, 30% oxygen) and racemic epinephrine. At 1 week, bronchoscopy is performed. Postoperative dilation or subsequent stent insertion are uncommon but are guided by this surveillance endoscopy. If the patient has a stent in place, it is removed at approximately 6 weeks, although the timing is variable depending on the disease in the subglottis and/or glottis.

      References

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        • Bryce DP
        The management of laryngeal stenosis by resection and direct anastomosis.
        Laryngoscope. 1974; 84: 940-957
        • Pearson FG
        • Cooper JD
        • Nelems JM
        • et al.
        Primary tracheal anastomosis after resection of the cricoid cartilage with preservation of recurrent laryngeal nerves.
        J Thorac Cardiovasc Surg. 1975; 70: 806-816
        • Grillo HC
        • Mark EJ
        • Mathisen DJ
        • et al.
        Idiopathic laryngotracheal stenosis and its management.
        Ann Thorac Surg. 1993; 56: 80-87
        • Maddaus MA
        • Toth JLR
        • Gullane PJ
        • et al.
        Subglottic tracheal resection and synchronous laryngeal reconstruction.
        J Thorac Cardiovasc Surg. 1992; 84: 1443-1450
        • Cooper JD
        • Pearson FG
        • Patterson GA
        • et al.
        Use of silicone stents in the management of airway problems.
        Ann Thorac Surg. 1989; 47: 371-378
        • Dedo HH
        • Fishman NH
        Laryngeal release and sleeve resection of tracheal stenosis.
        Ann Otol Rhinol Laryngol. 1969; 78: 285-296
        • Maddaus M
        • Pearson FG
        Subglottic resection.
        in: Pearson FG Deslauriers J Ginsberg RJ Thoracic Surgery. Churchill Livingstone, New York, NY1995: 321-332