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Use of Silicone Stents in the Management of Subglottic Stenosis

1997; Wiley; Volume: 107; Issue: 11 Linguagem: Inglês

10.1097/00005537-199711000-00024

1531-4995

Jeffrey A. Kurrus, Steven D. Gray, Mark R. Elstad,

Esophageal and GI Pathology

The management of subglottic stenosis, an increasingly common clinical problem, is complex and challenging. Two surgical approaches have traditionally been used-segmental resection versus expansion of the stenosed segment with cartilage or bone grafts.1-3 Endoscopic therapies also play a major role in management of subglottic stenosis because segmental resection may be technically difficult in the absence of a stenosis-free subglottic space, surgery is not uniformly successful, and many patients are not suitable operative candidates. The endoscopic management of airway stenosis4 and the use of airway stents5 have been recently reviewed in detail. The caliber of the subglottic airway may be improved endoscopically by laser photodissection and/or mechanical dilation; however, stenosis frequently recurs, and repetitive procedures may be required to maintain airway patency.4 Stenting with a metal alloy tube was first used in the 1950s6 in an effort to prevent the recurrence of tracheal narrowing. Montgomery7 introduced the “T tube” to treat subglottic stenosis in 1965. Dumon8 reported the use of silicone stents for airway narrowing in 1990. Colt et al.9 and Temes et al.10 recently described their techniques for the use of silicone stents in the treatment of subglottic stenosis. This report describes a new endoscopic approach to treatment of subglottic stenosis using silicone stents. Silicone stents effectively prevent the recurrence of subglottic stenosis following dilation and, in most cases, provide airway function that is compatible with normal, or near-normal, exercise capacity and voice. The primary goals of preoperative evaluation are to determine the cause, anatomy, and functional significance of subglottic airway narrowing. It is important to recognize diseases that might limit the effectiveness of treatment aimed solely at the subglottic larynx. For example, if there is glottic dysfunction or more distal airway disease, treating solely the subglottic larynx may not correct dyspnea. Sarcoidosis, Wegener's granulomatosis, or other systemic diseases may be more appropriately treated with immune suppressants or other medications. A careful history is taken and physical examination performed on all patients. Noninvasive laboratory testing (arterial blood gas values, spirometry, exercise testing) and airway imaging (chest radiography, computed axial tomography) are used selectively for diagnosis and to confirm the functional significance of airway narrowing. Two points are worthy of emphasis. First, extensive noninvasive testing is expensive and is not required in most cases. The combination of spirometry and a chest radiograph is adequate for most patients. Second, endoscopic evaluation of the airway while the patient is spontaneously breathing provides valuable information regarding dynamic function of the larynx, glottis, and trachea. This is usually performed at the time of stent placement, although it may be performed preoperatively in selected cases. The patient is given methylprednisolone, 125 mg, intravenously and cefazolin sodium, 1 g, intravenously on call to the operating room. Fiberoptic laryngoscopy and bronchoscopy are performed with local anesthesia to observe dynamic function of the airway and to examine for synchronous distal airway disorders. Anesthesia is induced, the patient is paralyzed, and exposure is obtained using a suspension laryngoscope large enough to accommodate a rigid bronchoscope. If a preexisting tracheostomy is present, it is used for ventilation. As an alternative, intermittent ventilation is administered through a small endotracheal tube or jet ventilation catheter. Management of ventilation requires close cooperation with the anesthesiologist, and the approach must frequently be modified during the operation. The length of the stenotic segment is determined by placing a telescope through the suspension laryngoscope. The tip of the telescope is positioned at the distal end of the stenosis, and the point at which the telescope contacts the laryngoscope opening is marked. Next, the telescope is withdrawn until the tip is at the proximal end of the stenosis, and the new position on the telescope at the laryngoscope opening is marked. The distance between the two marks on the telescope is the length of the stenosis. The initial diameters of the stenosis and of the normal trachea below are estimated visually using the telescope and Pilling dilators as probes. Pilling dilators of progressively larger diameter are used to dilate the stenosis to a maximum of 18 mm or to the diameter of the trachea distal to the stenosis if it is smaller than 18 mm. The CO2 laser may be used as an adjunct to dilation in two situations. Aggressive dilation of tight cicatricial stenoses may tear or rupture tissue. If the lines of dissection extend posteriorly through the membranous trachea into the esophagus, a tracheoesophageal fistula may result. Thus, if “excessive” force is required to pass dilators of appropriate size, the CO2 laser is used to create radial incisions in the anterior portion of the stenosis. We believe this may reduce the likelihood of posterior dissection. The laser is also used to resect stenotic tissue when dilation alone does not create a space large enough to accept the stent. Careful attention is given to choice of stent size. A stent with the diameter of the largest or next-to-largest dilator is used. This allows the airway to be maintained at its maximally dilated size. The silicone stents(Dumon Tracheobronchial Stent, Bryan Corporation, Woburn, MA) are available in diameters ranging from 10 to 16 mm. The length depends on the length of the stenosis and the condition of the trachea distal to the subglottic narrowing. The stent need only be long enough to span the stenosis if there is no tracheomalacia. If there is tracheomalacia distal to the subglottic stenosis, the stent should be of sufficient length to prevent collapse over the distal limb. Following dilation, the silicone stent is loaded into a specifically designed introducer (Stent Introducer System, EFER, LaCiotat, France). The introducer is passed through the suspension laryngoscope and the stent is expelled across the stenotic segment. The position is adjusted as required using a microscope and microlaryngeal instruments or a telescope and optical instruments. If the chosen stent does not appear to be the optimal size, it may be removed using forceps and the procedure repeated with a new stent. As illustrated in Figure 1, internal fixation of the stent is performed using a technique modified from the external fixation method of Colt et al.9 The anterior neck is prepared and draped using standard techniques. The stent is monitored using a telescope and supported with forceps as required. The skin, anterior wall of the trachea, and anterior wall of the stent are pierced with a 16-gauge intravenous angiocatheter (Jelco) that enters the stent just distal to the midpoint. A second angiocatheter is placed approximately 1 cm proximal to the initial catheter. The inner metal cannulas of the angiocatheters are removed, leaving the Teflon sheaths in place through the tracheal wall and stent. A loop of 3.0 polypropylene suture (Prolene) is passed through the proximal catheter. The end of another suture is placed through the distal catheter, grasped with microlaryngeal forceps, and pulled through the loop extending from the proximal catheter (Fig. 1). The distal suture is drawn out of the proximal catheter using the suture loop. The skin is incised between the two catheters, the dissection carried down to the strap muscles, the catheters removed, the suture tied, and the skin closed. Management of subglottic stenosis using internal fixation of a silicone stent. The stenosis has been dilated and a stent of the appropriate size positioned across the stenosis. Bottom: 16-gauge angiocatheters have been placed through the skin, the anterior wall of the trachea, and the stent. A 3.0 polypropylene suture extending from the distal catheter has been pulled through a loop of suture extending from the proximal catheter using a microlaryngeal forceps.Top: The distal suture has been drawn out of the proximal catheter using the suture loop. Next, the skin will be incised between the two catheters, the dissection carried down to the strap muscles, the catheters removed, the suture tied, and the skin closed. The final position of the stent is verified endoscopically. The suspension laryngoscope is removed and the lungs ventilated, either by mask or through a small uncuffed endotracheal tube placed through the stent under direct vision, until the patient is awake and breathing spontaneously. The patient is observed in hospital overnight and discharged the next day. Specific instructions are given on the management of airway stents, including the use of large-volume ultrasonic nebulization to facilitate clearance of secretions. Most patients have been given a 4-day course of prednisone (60 mg/d orally) and cephalexin (500 mg four times/d orally). Follow-up includes clinic visits and fiberoptic bronchoscopy at 1 week, 3 months, and 1 year, unless indicated more frequently on clinical grounds. There are several alternatives to each step of the operative procedure that must be considered. The approach to ventilation must be individualized, requires close cooperation with the anesthesiologist, and is frequently modified throughout the course of the procedure. Routine tracheostomies are not required. We believe that the suspension laryngoscope provides the most efficient access for dilating and stenting the subglottic larynx in the majority of patients. We use a ventilating rigid bronchoscope when it is technically difficult to work through the suspension laryngoscope. Dilation is performed with the tip of rigid bronchoscope or balloon catheters. Photodissection is accomplished with either a neodynium-yttrium-aluminum-garnet (Nd:YAG) or potassium-titanyl-phosphate (KTP) laser delivered through a flexible fiber. Our experience using silicone stents in the treatment of subglottic stenosis over the past 24 months is summarized in Table I. Three patients had subglottic stenosis following intubation and/or tracheostomy, and two had idiopathic subglottic stenosis. In three patients a stent was chosen, rather than an open surgical approach, because they had failed previous laryngotracheoplasties. Two patients were believed to be poor surgical candidates because of underlying illnesses. All five had an immediate improvement in dyspnea after the stent was placed. Complications included transient vocal fold edema (two patients) and distal migration (one patient whose stent was initially placed without fixation). All patients are alive and well with stents in place for 8 to 24 months. One patient was treated with a sleeve resection of the trachea for recurrence of the stenosis when the stent was removed at 11 months. This patient had a significant neurologic deficit and uncertain prognosis at the time the stent was placed. She had made a significant recovery, and we elected to proceed with an open repair at the time of the recurrence rather than placing another stent. Two patients required significant variations from the general operative procedure described earlier (Table I; patients 1 and 2). These cases are presented in detail to illustrate decisions and modifications in approach that may be required in the operating room when dealing with such complicated patients. A 67-year-old woman with a history of cervical spine fusion for rheumatoid arthritis underwent laryngotra-cheoplasty for idiopathic subglottic stenosis 3 years previously. Six months before operation she noted increasing dyspnea on exertion and was found to have recurrent subglottic stenosis. Her symptoms progressed, and she was taken to the operating room, where fiberoptic bronchoscopy revealed severe subglottic stenosis beginning 1.5 cm distal to the vocal cords. Because of her cervical spine disease, we were unable to visualize the glottis with either a suspension laryngoscope or a rigid bronchoscope. We elected the following approach as an alternative to repeat rib grafting. The trachea was intubated with a small, uncuffed endotracheal tube over the pediatric bronchoscope, and a tracheostomy was performed to ensure adequate control of the airway. The stenosis was dilated using 5-and 9-mm angiocatheter balloons (Boston Scientific Corporation, Watertown, NH) placed through a flexible fiberoptic bronchoscope from above. A laryngofissure was carried cephalad through the cricoid cartilage and previous rib graft, and into the thyroid cartilage. A silicone stent (10-mm diameter, 30-mm length) was placed through the laryngofissure and positioned 5 mm below the vocal folds using the flexible bronchoscope from above. The stent was sutured to the anterior tracheal wall, and the laryngofissure closed. The patient had an uneventful hospital course and was discharged 6 days after the procedure with a plugged tracheostomy tube. The tracheostomy tube was removed 1 week after hospital discharge, and she is doing well 15 months later. To our knowledge, this represents the first reported case using a Dumon silicone stent placed through a laryngofissure to treat subglottic stenosis. This case highlights problems that are encountered in managing the airway of patients with cervical spine disease. It demonstrates the type of alterations in surgical plan that may be required in the operating room. The patient had severe cervical arthritis, documented craniovertebral instability, and a history of spine fusion. Because of these problems, she was unable to tolerate even a small amount of neck extension. Therefore we used a flexible bronchoscope for visualizing the larynx and the position of the stent in relationship to the vocal folds but actually placed the stent by means of the laryngofissure approach. A 60 year-old male diabetic had been treated for 2 years with a tracheostomy for subglottic stenosis and impaired abduction of his vocal folds following a stroke and prolonged intubation. He was plagued by poor voice, persistent purulent secretions, and distaste for the cosmetic appearance of the tracheostomy. Fiberoptic bronchoscopy revealed an apparently adequate glottic aperture and severe subglottic stenosis extending distally to the stoma. He was not considered a good candidate for laryngotra-cheoplasty because of severe diabetes and other problems including coronary artery disease, peripheral vascular disease (recent stroke), and chronic renal insufficiency. The patient was taken to the operating room, and a silicone stent (14-mm diameter, 30-mm length) was placed using the method described earlier. The operation was uneventful, and he was discharged the next day. He noted increasing stridor 1 week after stent placement, and bronchoscopy revealed the vocal folds to be edematous and closed with the exception of a posterior chink. The stent was in good position and free of secretions. He had some clinical improvement over the next day following treatment with intravenous steroids and inhaled epinephrine; however, there was little change the appearance of the glottis. Therefore he was taken to the operating room for a cordotomy11 that resulted in a marked improvement in stridor and dyspnea. Stent placement for subglottic stenosis is most likely to be successful in patients who have normal glottic function. This is one reason it is important to perform endoscopy with the patient awake before endoscopic dilation and stent placement. We were not enthusiastic about operating on this patient; however, he was very interested in making the attempt to remove his tracheostomy. Resection of subglottic stenosis may be possible if the glottis has an adequate aperture, even if it is paralyzed.1, 3, 11 Alternative operative approaches to cordotomy include cord lateralization and arytenoidopexy. The optimal approach to management of subglottic stenosis has yet to be defined. The use of endoscopic therapy with stent placement may play an increasing role in the management of this disorder. Herein, we present our method for placing and fixing silicone stents to treat subglottic stenosis or malacia. Our approach is multidisciplinary, making use of the skills of both an invasive pulmonologist and an otolaryngologist. The treatment of subglottic stenosis is challenging, and often the planned procedure must be modified in the operating room. We have found that having both specialists present in the operating room provides greater options for airway evaluation and treatment of these complicated cases. Our method differs in several ways from the previous techniques described for the use of silicone stents for subglottic stenosis.9, 10 Although we have considerable experience with the use of rigid bronchoscopes, a suspension laryngoscope allows for more efficient dilation, lasering, and stent placement for subglottic stenosis in our hands. Depending on the endoscopist's personal experience and the patient's anatomy, use of either a suspension laryngoscope or rigid bronchoscope may be the most appropriate. When compared with the method of Temes et al.,10 we believe that our approach is technically easier and allows for quicker and more accurate positioning because the sutures are placed following precise location of the stent. There are no data on the relative risk of internal versus external fixation5 of these stents. We favor internal fixation because it provides a better cosmetic result and no extra care is required for activities such as shaving. We have not yet encountered subcutaneous infection or granuloma formation at the suture site. The major potential complications reported for silicone stents include migration, obstruction by secretions, and obstruction by inflammatory tissue overgrowth.5, 8-10 As suggested by others,9, 10 fixation to prevent migration is particularly important in the subglottic area. We initially placed one subglottic stent without internal fixation (Table I; patient 3), only to have it migrate distally in 2 days. The stent was repositioned and fixed as described, and the patient has had no further difficulties. We routinely use large-volume ultrasonic nebulization of normal saline to maintain fluidity of airway secretions and enhance their clearance. Removal of inspissated secretions by flexible bronchoscopy at regular intervals may be required in certain individuals, in particular, immediately following stent placement. We have not yet seen evidence of obstructing granulation tissue induced by subglottic stents, although it has been a problem in several patients with stents in other locations. Two of our patients had postoperative vocal fold edema that resolved over several weeks without specific therapy. We speculate that placement of a subglottic stent may impair lymphatic drainage in some patients. Glottic edema might be caused by the underlying disorder, dilation and/or laser resection, the size or type of stent, direct surgical trauma to the glottis, or other factors. Currently we place the stents at least 4 to 5 mm below the vocal folds because of a concern that closer placement may be more likely to cause vocal fold edema. Silicone stents are an excellent addition to the armamentarium of treatments available for subglottic stenosis. From the otolaryngological perspective, stent placement takes longer than performing a tracheostomy but is much less involved than performing a tracheoplasty or laryngoplasty. The procedure for stent placement and fixation can be performed using readily available instruments and techniques. Total operative time ranges from 1 to 2 hours and is decreasing as we gain experience. A number of questions remain regarding the use of airway stents.4, 5, 8-10 Most stents currently available are made of either silicone or wire mesh. We prefer silicone stents in the subglottic airway because they may be removed endoscopically, yet migration is easily prevented by fixation with suture. In contrast, removal of self-expanding metal stents is nearly impossible. In select cases that do not have a major component of malacia, it would be reasonable to attempt a trial of stent removal. Patient 5 (Table I) had a major neurologic deficit and uncertain prognosis when we initially placed a stent for tracheal stenosis following prolonged intubation in the setting of subarachnoid hemorrhage. Eleven months later, the patient had recovered to near-normal functional status and we removed the stent. The cicatricial stenosis recurred over several weeks. After discussing the alternatives, including replacing the stent, we elected to perform a sleeve resection as “definitive” therapy. The role of stenting in comparison to traditional surgical approaches or other endoscopic procedures has yet to be defined. Many authors maintain that open surgical intervention should be used whenever possible as primary therapy for subglottic stenosis.1, 2 Indeed, we have used silicone stents to treat disease that has been resistant to standard therapies. In contrast, some authors4 believe that “all conservative avenues should be exhausted before committing to an open reconstruction.” It is important to note that further open surgical options are not precluded by initial use of a stent, as demonstrated by patient 5. The results of standard surgical approaches have not been compared with those of endoscopic stent placement using modern techniques as primary therapy for subglottic stenosis. Certainly, this area warrants further exploration. We acknowledge members of the Department of Anesthesiology and the Laser Surgery Institute (University of Utah Medical Center) for assistance with management of these challenging cases. In addition, we thank Dr. James Harrell(University of California San Diego Medical Center) for helpful discussions. We would like to thank Mr. Julian Maack of the University of Utah Medical Illustration Service for his illuminating illustration.