- Email: [email protected]
Complications of metallic stents in the pediatric airway
Complications of metallic stents in the pediatric airway LYNNE H. Y. LIM, MD, ROBIN T. COTTON, MD, RICHARD G. AZIZKHAN, MICHAEL J. RUTTER, FRACS, Cincinnati, Ohio
OBJECTIVE: Our aim was to present our experience with complications caused by placement of metallic stents in the pediatric airway. DESIGN AND SETTING: We conducted a retrospective study of the medical records of patients with complications resulting from metallic stent placement, managed by the senior authors between 1993 and 2002. RESULTS: Nine children had complications associated with the placement of metallic airway stents. Of these, 8 children required stent removal. Granulation tissue and tracheal stenosis were seen in all 7 children with long standing stent placement. There was 1 stent death in this series. CONCLUSIONS: Metallic airway stents can cause significant complications in the pediatric airway. These complications may supersede the airway compromise that necessitated their initial placement. As such, metallic stent placement should be approached with caution. The likelihood and severity of complications increase with time, as do the difficulties encountered upon removal. The proportion of patients in whom metallic stents may be placed “permanently” without complications is not known. Therefore we recommend that metallic airway stents be considered a temporizing measure of limited duration. (Otolaryngol Head Neck Surg 2004;131:355-61.)
From the Division of Pediatric Otolaryngology/Head and Neck Surgery, Cincinnati Children’s Hospital Medical Center (Drs Lim, Cotton, and Rutter); the Department of Otolaryngology, University of Cincinnati College of Medicine (Dr Cotton and Rutter); the Aerodigestive and Sleep Center, Cincinnati Children’s Hospital Medical Center (Drs Cotton, Azizkhan, Wood, and Rutter); the Division of General and Thoracic Pediatric Surgery, Cincinnati Children’s Hospital Medical Center (Dr Azizkhan and Cohen); and the Division of Pulmonary Medicine Research, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH (Dr Wood). Presented at the Annual Meeting of the Academy of Otolaryngology–Head and Neck Surgery, Orlando, FL, September 21-24, 2003. Reprint requests: Michael J. Rutter, FRACS, Division of Pediatric Otolaryngology/Head and Neck Surgery, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039; e-mail, mike. [email protected] 0194-5998/$30.00 Copyright © 2004 by the American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. doi:10.1016/j.otohns.2004.04.007
MD,
ROBERT E. WOOD,
MD, PHD,
ALIZA P. COHEN,
MA,
and
I n recent years, metallic airway stents have become increasingly popular in the management of challenging tracheobronchial obstruction in the adult and pediatric airway. In most adults, stents are placed to alleviate intraluminal obstruction as a result of cicatrix formation or benign or malignant neoplasms. In children, however, they are usually placed to manage congenital or acquired tracheomalacia or tracheobronchomalacia. The overall preliminary success1-7 of these small, intriguing devices, together with the known drawbacks of traditional approaches, inspired receptivity and eagerness to attempt this novel approach. Reported advantages of metallic stents have included their relative ease of application, their availability in a wide range of sizes, and their putative ability to maintain mucociliary function. Additionally, in some patients, they can accommodate growth by being periodically dilated until they attain their maximum physical capacity.6,8 Although research has shown that judicious stent placement can alleviate major airway obstruction and provide life-saving airway improvement in many patients, studies and case reports continue to document serious and unsettling complications, particularly with longer-term stenting, that are increasingly tempering the initial enthusiasm.9-12 Most authors agree that removal of metallic stents can be perilous, especially after the stent has been in place for months or years and has completely epithelialized, or is so deeply embedded in the wall of the airway that it is not accessible.6,12,13 As such, in some patients, these devices have been considered permanent.6,8 In the first published study to focus on stent complications, Zakaluzny et al12 identified and analyzed complications from several types of stents in 9 patients (including 1 infant and 1 adolescent) who were treated for either benign or malignant tracheobronchial diseases. Results revealed that the most common complications included stent migration and fracture, granulation tissue formation around the stent, problems with mucociliary clearance, poor patient tolerance, and problems with placement and removal. These complications were found to occur more frequently in long-term treatment of benign conditions. In addition, in this study, our aim was to specifically focus on complications of metallic stents in the pediatric airway. We present our experience with 9 patients, 8 of whom required stent 355
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356 LIM et al
Table 1. Stent types, complications, and treatment
Patient no.
Type of stent
Stenosis
Airway obstruction/ granulation
1
Palmaz
⻬
⻬
2
Wallstent
⻬
⻬
3
Wallstent
⻬
⻬
4
Wallstent
⻬
⻬
5
Silicone-coated
⻬
⻬
6 7
Palmaz Wallstent
⻬
⻬
8
Palmaz
9
Palmaz
Fracture fragmentation
Erosion/ migration into adjacent structures
⻬
⻬
⻬ (iatrogenic)
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬ ⻬
⻬ (iatrogenic, bent stent)
Intraluminal exposure
Partial integration into airway wall
⻬ ⻬
⻬
⻬
⻬
⻬
⻬
Treatment Open and endoscopic stent removal (with cardiopulmonary bypass) Open stent removal with LTR Endoscopic removal of remnant wires and tracheal dilation Open stent removal and subsequent LTR Endoscopic stent removal Patient died Endoscopic stent removal Endoscopic stent removal Endoscopic stent removal
LTR, laryngotracheal reconstruction.
removal. Complications are outlined and airway management strategies are discussed. PATIENTS AND METHODS We reviewed the medical records of patients with complications resulting from metallic stent placement who were managed by the senior authors (M.J.R., R.G.A., R.T.C.) between 1993 and 2002. In patients 1 through 7, stents were placed by physicians in other institutions. In patients 8 and 9, stents were placed by one of the senior authors. The airway was assessed with regard to stent migration, granulation tissue formation, and stent-associated stenosis, and management strategies were documented. This study was approved by the Institutional Review Board of Cincinnati Children’s Hospital Medical Center, Cincinnati, OH. RESULTS The patients in series included 5 males and 4 females. These patients ranged in age from 1 month to 40 months at the time of stent placement. There was wide variation in the duration of stenting, ranging from 1 month in patient 8, to 5 years in patient 7. In 4 patients, congenital tracheobronchomalacia was the predominant airway problem necessitating stent placement. In 4
other patients, placement was performed for acquired tracheal and/or bronchial collapse or stenosis. In 1 patient, a stent was inserted as part of a surgical repair of complete tracheal rings. Palmaz stents (Johnson & Johnson International Systems Co., Warren, NJ) and Wallstents (Schneider Corp, Minneapolis, MN) were each inserted in 4 patients, whereas an experimental silicone-coated wire stent was inserted in 1 patient. Because our institution is a quaternary care referral center, our population comprised a highly select subgroup of patients with a wide spectrum of problems and complications. To illustrate the unique issues involved, we present below a detailed synopsis of these cases. A broad overview of our series is presented in Table 1. Patient 1 This female was born at 33 weeks’ gestation with VATER syndrome, requiring gastrostomy tube placement and repair of a tracheoesophageal fistula and esophageal atresia. Though discharged from hospital at 1 month of age, she was readmitted at 3 months with respiratory failure due to severe tracheobronchomalacia. An aortopexy was unsuccessful, requiring tracheotomy and continuous positive airway pressure (CPAP). At 16 months of age, de-
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cannulation was achieved with placement of 5 stents (Palmaz). One stent was inserted in each main stem bronchus, 2 in the trachea, and the fifth appears to have been inadvertently placed in a large tracheoesophageal fistula pouch. Ongoing problems with stent fracture and restenosis required removal and replacement of the bronchial stents twice over the next month. By the age of 18 months, tracheotomy and CPAP were required to alleviate life-threatening airway obstruction. By 35 months of age, life-threatening airway obstruction prompted referral to our institution. Assessment at that time showed fragmented stents in the trachea and both bronchi, with tracheal stenosis, tracheal and bronchial collapse, and a highly unstable airway. Because the child was thought to be at imminent risk of death, the stents were removed within 24 hours. Although most of the tracheal and right bronchial stents were endoscopically removed in a piecemeal fashion, the left bronchial stent required removal under cardiopulmonary bypass through an open bronchotomy. Acquired stenosis within the bronchus required placement of a pericardial patch. The fifth stent could not be located. One month later, severe left bronchomalacia (of a devitalized pericardial patch) required placement of a new Palmaz stent. The airway was stabilized following this surgery. Though the child remained tracheotomy-dependent, she was weaned off CPAP. At 52 months of age, severe dysphagia developed and was found to be caused by the fifth stent having eroded into the esophagus. This stent was removed endoscopically from the esophagus in a piecemeal fashion. Removal was an extremely difficult procedure, with damage to the esophageal wall. The esophageal stricture remained recalcitrant as a result of a single retained wire, which was removed at 57 months of age. Currently (at 72 months of age) the esophagus has a minimal asymptomatic stricture, and the trachea and bronchi have ongoing mild granulation, associated with wire remnants. These remnants will eventually require removal, as will the left bronchial stent. Patient 2 As a result of severe neonatal idiopathic hepatitis, this male infant required a liver transplant at the age of 11 months. A tracheotomy was placed 1 month later because of prolonged ventilatory requirements. He was decannulated at 30 months of age, and had a stomal closure at 33 months of age. Three weeks after stomal closure, airway compromise associated with tracheal stenosis at the stoma site required placement of a stent (Wallstent). Ongoing problems with granulation and stenosis required repeated laser intervention, steroid
LIM et al 357
injections, and tracheal dilations. At 80 months of age, respiratory arrest prompted transfer to our institution. Evaluation revealed a grade 3 subglottic stenosis associated with the proximal end of the stent, intraluminal granulation tissue, and a mild stenosis associated with the distal end of the stent. A section of the distal stent was fully exposed in the airway, but 80% of the stent was fully mucosalized and the proximal end was deeply buried in scar tissue. A laryngotracheal reconstruction with anterior and posterior costal cartilage grafting was performed as a single-stage procedure, and the stent was completely removed in a piecemeal fashion. At 83 months of age, the airway was widely patent and the patient was asymptomatic. Patient 3 This male infant was diagnosed in utero with a severe right-sided congenital diaphragmatic hernia. He underwent fetal surgery at 26 weeks’ gestation, and a tracheal clip was placed. At 31 weeks’ gestation, an ex utero intrapartum treatment (EXIT) procedure was performed and the tracheal clip was removed. The neonatal period was unstable, and following repair of the diaphragmatic hernia extubation could not be achieved because of tracheal stenosis at the site of the tracheal clip placement. At 2 months of age, 2 stents (Wallstents) were placed, allowing extubation 1 week later. Because of persistent tracheal stenosis, the stents were removed at 27 months of age. Removal was accomplished through an open approach, and an anterior cartilage graft was inserted. Because of persistent stridor, the child was referred to our institution at 28 months of age. Evaluation revealed persistent severe tracheal stenosis associated with retained tracheal wires. These wires were removed endoscopically, and the area of stenosis was dilated and treated with mitomycin C. Though follow-up at 50 months of age showed minimal tracheal stenosis, the child was asymptomatic. Patient 4 This twin female was born at term with a double outlet right ventricle and pulmonic stenosis, requiring a right Blalock Taussig shunt at 10 days of age. At 6 months of age, she was noted to have intermittent episodes of tachypnea. At 16 months of age, a Rastelli cardiac repair required prolonged intubation. Extubation was achieved only after insertion of a wire stent (Wallstent) to manage tracheomalacia. By 18 months of age, subglottic stenosis had developed at the proximal end of the stent despite subglottic laser treatment. By 21 months, numerous emergent admissions to hospital for an unstable airway prompted transfer to our unit. Assessment at that time indicated a grade 3 subglottic
358 LIM et al
stenosis associated with the proximal end of the stent, which was deeply embedded in scar tissue. The stent could not be removed endoscopically. To stabilize the airway, a tracheotomy was placed, with several wires being cut to allow placement of the tube. The stent was firmly adherent and could not be safely removed through the tracheotomy incision. By 24 months of age, bronchial compromise associated with granulation tissue formation at the lower end of the stent necessitated removal of the stent in an open procedure. This procedure was performed in the cardiac operating room where cardiopulmonary bypass facilities were readily available. Although stent removal was challenging and was performed in a piecemeal fashion, cardiopulmonary bypass was not required. Persistent grade 3 subglottic stenosis required laryngotracheal reconstruction at 30 months of age. Because of tracheomalacia, however, decannulation could not be achieved until 65 months of age. By 71 months of age, the patient was asymptomatic, without subglottic stenosis and with only mild tracheomalacia. Patient 5 This term female was born with esophageal atresia and a distal tracheal esophageal fistula, which were repaired during the neonatal period. Although she initially did well, between 6 and 9 months of age she had repeated life-threatening apneic episodes as a result of severe tracheomalacia involving 65% to 75% of the length of the trachea. A silicone-coated metallic stent (an experimental prototype for clinical study) was inserted and her apneic episodes ceased. Within 4 months, she began wheezing and showed signs of air trapping on chest x-ray. Upon referral, endoscopy revealed granulation tissue at the distal interface between the stent and the trachea at the level of the carina. This created a stenotic orifice to each main bronchus. The granulation tissue was endoscopically removed and the patient underwent 2 courses of systemic steroids, with recurrence of granulation tissue upon cessation of each course. Eight months after stent insertion, recurrent airway obstruction necessitated endoscopic stent removal. The stent was found to be frayed and wires protruded through the silicone coating into the tracheal wall and the lumen of the airway. Subsequent to stent removal, tracheomalacia was not as severe as it had been prior to stent insertion and the patient remained free of major symptoms. At age 7, this child remained asymptomatic. Patient 6 Stridor was noted in this 2.5-kg male infant immediately after delivery, but intubation with a standard tracheal tube was not was possible. Endoscopy and CT
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scan corroborated the presence of complete tracheal rings extending from just below the subglottic region of the larynx to the carina. An echocardiogram revealed a pulmonary artery sling. During the neonatal period, the patient underwent a repair of the tracheal stenosis and pulmonary artery sling under cardiopulmonary bypass. The anterior wall of the trachea was divided and a pericardial patch inserted. A stent (Palmaz) was placed to buttress the airway. Two weeks after this procedure, the stent eroded through the wall of the pericardial patch, causing mediastinitis, which was the ultimate cause of death. Postmortem examination showed that the distal portion of the stent had eroded into the pulmonary artery. Patient 7 This term male required a complete small bowel resection at 10 days of age following a volvulus. At 8 months of age, he required both small bowel and liver transplantation and long-term ventilatory support via tracheotomy. Though he was decannulated at 40 months, severe tracheomalacia necessitated stent placement. For the next 5 years, he had ongoing problems with the stent, requiring multiple laser procedures to remove granulation tissue. He was referred to our institute at 86 months of age with stridor and stentassociated stenosis. Pulmonary function testing revealed severe fixed airway obstruction. Endoscopic evaluation showed exuberant granulation tissue, stenosis, and a partly integrated stent (Wallstent), which was removed in a piecemeal fashion. Follow-up at 89 months of age showed that tracheal diameter was much improved. At this time, and at subsequent follow-ups, residual strands of wire were removed. At 92 months of age, the patient was asymptomatic with minimal tracheal narrowing, normal pulmonary function testing, and bronchoscopic improvement, however, residual wires remained. Patient 8 This term female was born with mild respiratory distress. At 10 months of age, increasing respiratory compromise prompted admission and investigation. A pulmonary artery sling was diagnosed and subsequently repaired under cardiopulmonary bypass. Severe postoperative respiratory compromise required placement on extracorporeal membrane oxygenation, and severe tracheal stenosis due to complete tracheal rings was diagnosed. A bovine pericardial patch was used to repair the trachea and mainstem bronchi. Following an episode of cardiopulmonary arrest at 13 months of age, a tracheotomy was placed. Distal tracheal collapse and granulation formation resulting in recurrent acute airway compromise required multiple bronchoscopies
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over the next 20 months, requiring this infant to spend much of her life in the hospital. She was transferred to our institution at 33 months of age. Assessment revealed a grade 4 upper tracheal stenosis at the stomal site and distal tracheal and bronchial stenosis and collapse. The mainstem bronchi were identified with great difficulty. The patient required a distal tracheoplasty and carinal reconstruction with a tracheal homograft replacing the anterior distal trachea and mainstem bronchi. Tracheal homografts usually require stenting, but silastic stents were too large to be accommodated, so the airway was maintained with a long tracheotomy tube and CPAP. An unstable postoperative course and left bronchial collapse required placement of a left bronchial stent (Palmaz) at 35 months of age, which we had planned to remove within 6 months. At 36 months, follow-up bronchoscopy at the referral hospital resulted in the stent being bent. Upon return to our institution, the proximal end of the stent was overlying the entrance to the left mainstem bronchus, allowing ventilation but precluding bronchoscopic evaluation. The stent was removed without difficulty. At a 44-month follow-up, the distal airway was widely patent. The patient was stable on room air without CPAP and with a short tracheotomy tube lying above the level of the homograft. We plan to proceed with reconstruction of the upper airway stenosis at 50 months of age to achieve decannulation. Patient 9 This male was born at 24 weeks’ gestation as a result of premature rupture of amniotic membranes, endometritis, and amnionitis. As a newborn, he required intubation and prolonged ventilation for severe respiratory distress syndrome, which led to bronchopulmonary dysplasia and chronic lung disease. A tracheobronchoscopy at 5 months of age showed severe tracheomalacia extending from the thoracic inlet to the carina, and involving both main and segmental bronchi. A tracheostomy was placed at this time. However, because of severe airway obstruction related to distal tracheobronchomalacia, stents were inserted in both main bronchi and in the distal half of the trachea. Although the patient showed initial improvement, circumferential obstructing granulation tissue created stenotic openings in both main bronchi. Upon referral, the patient was treated with a combination of balloon dilation to flatten the granulation tissue within the stent area and repeated courses of high-dose steroids, with recurrence of granulation tissue formation upon cessation of each course. After being in place for 5 months, 2 of the 3 stents were removed and the patient was managed with chronic ventilator support. The left bronchial stent had become
LIM et al 359
incorporated into the bronchial wall and could not be safely removed; it was thus left in place. The patient died of progressive chronic lung disease at 18 months of age. DISCUSSION The placement of metallic stents was initially hailed as being a comparatively safe approach to achieving airway patency in children with tracheomalacia, tracheobronchomalacia, and a number of other specific airway conditions.1,3,4 Our experience over the past 9 years suggests that this approach carries significant risks and may be associated with major aerodigestive and vascular complications. These complications can occur during stent placement, over the period of time in which stents remain in the airway, and during the removal procedure. In light of these considerations, we rarely place metallic airway stents. This series represents only a fraction of the pediatric patients in whom metallic airway stents have been placed—the numerator being children with complications arising from stent placement and the denominator being those whose stents are asymptomatic or who have not been referred to our institute. Unfortunately, the size of the denominator is unknown, and we therefore cannot determine the overall complication rate. It is probable that in some children metallic stents may be tolerated indefinitely without complication, and therefore not warrant removal. However, the proportion of children in whom this is the case is unknown. Therefore, it is our opinion that the potential and severity of associated complications warrants limiting stent placement to patients in whom alternative approaches have failed or are contraindicated, and that they be placed with a view to eventual removal. In our routine practice, children with severe tracheomalacia are managed with aortopexy or placement of a tracheotomy tube that extends close to the carina. Those with severe tracheobronchomalacia are managed with tracheotomy and positive pressure support, either by CPAP, bilevel positive airway pressure, or ventilation. Another alternative is the use of Y tracheotomy tubes, though we have no experience with this technique. Though concerns about the use of these approaches are valid, problems that arise are generally easier to manage than those resulting from stent placement, and improvement of malacia with time is anticipated. The endoscopic evaluation of metallic stents must be carried out with caution, keeping in mind that instrumentation and manipulation when suctioning, replacing tracheal tubes, or performing endoscopic procedures may cause stent damage, fracture, or displacement. If
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subglottic or tracheal stenosis is present at either end of a stent in a child without a tracheotomy, bronchoscopy may induce edema and acute airway compromise. If fractured wires are present, they may protrude through the lumen and into the wall of the airway. During flexible bronchoscopy, these wires can “fish-hook” the bronchoscope, either damaging it or hampering its removal. We have found that the longer metallic stents are in situ, the greater the risk of complications and the more challenging the removal. In our series, there were only 2 children (patients 6 and 8) who had short-term stent placement and these were the only 2 who did not have stenosis, obstruction, granulation, or partial integration of the stent into the airway wall. Of the 7 patients with long-term stent placement, all had associated stenosis and granulation tissue, and 6 had partial integration of the stent into the airway wall. All of these complications have been previously reported, both in the adult and pediatric literature.4,9,12,14-16 Removal of long-standing metallic stents is complex, and achieving optimal outcomes requires the cooperative efforts of a team of pediatric subspecialists who are skilled in airway management and reconstruction. Dreaded complications that are perhaps underreported but that have been anecdotally discussed among clinicians include risks of tracheal tearing, lethal airway obstruction, and bleeding or erosion of the stent into a great vessel. Naschef9 likens the removal technique to that of “rolling spaghetti on a fork,” noting that it is “much more difficult and at least equally as messy.” The type of stent, the duration of stent placement, and the degree of integration and entrapment in the airway wall are all critical factors in determining and planning optimal approaches to stent removal. Palmaz stents consist of a heavy gauge tubular steel mesh, whereas Wallstents consist of many thin wires. The latter are thus more likely to be removed in many fragments. In general, the longer a stent has been in place, the more integrated into the airway wall it becomes, and the more difficult it is to remove. Visualization of the proximal end of the stent may allow for endoscopic removal, whereas a stent buried by a proximal stenosis effectively precludes endoscopic removal. In some cases, tracheoplasty or laryngotracheoplasty may be required at the time of stent removal. Endoscopic removal is best achieved by grasping the proximal end of the stent with an endoscopically guided alligator forceps, and, while steadying the shaft, rotating the forceps for several revolutions to wind the stent onto the jaws of the forceps (technique used in patients 1, 5, 7, 8, and 9). Once the forceps have been rotated, some force may still be required
to disengage the stent from the airway wall, and some wires may fracture and remain intraluminal. Because Palmaz stents have more structural integrity than Wallstents, they are more likely to be removed intact or in fewer fragments. In contrast, Wallstents may leave a nest of wires occluding the tracheal lumen. Though these wires may look unsettling, particularly to the anesthetist, they are flimsy, and a ventilating bronchoscope can be negotiated through them. Remnant wires are removed in a piecemeal fashion. There is inevitably some bleeding, but this is usually transient. Follow-up endoscopy within 1 week is recommended to evaluate mucosal healing. Open removal is indicated if there is stenosis burying the proximal end of the stent, if integration precludes safe endoscopic removal, or if laryngotracheal reconstruction is desired at the time of stent removal. Palmaz stents are best dissected free from the tracheal wall and then removed as a wire mass. Other stents usually require piecemeal removal. In some cases wire by wire removal may be advantageous in that each individual wire may slide out of a submucosal “tunnel,” leaving the mucosa intact. With open or endoscopic removal, remnant wire fragments may be retained. Although these fragments may be asymptomatic and not warrant further intervention, in some cases they may act as a nidus for further stenosis. In some patients, wire fragments continue to migrate and eventually protrude into the lumen of the airway or esophagus, thereby permitting subsequent endoscopic removal. CONCLUSIONS Metallic airway stents can cause significant complications in the pediatric airway. These complications may supersede the airway compromise that necessitated their initial placement. As such, metallic stent placement should be approached with caution. Removal of long-standing stents is challenging. When stent placement is required, we recommend that placement be considered a temporizing measure for a limited duration. REFERENCES 1. Mair EA, Parsons DS, Lally KP. Treatment of severe bronchomalacia with expanding endobronchial stent. Arch Otolaryngol Head Neck Surg 1990;116:1087-90. 2. Filler RM, Forte V, Fraga JC, et al. The use of expandable metallic airway stents for tracheobronchial obstruction in children. J Pediatr Surg 1995;30:1050-6. 3. Bousamra M, Tweddell SS, Wells RG, et. al. Wire stent for tracheomalacia in a five year old girl. Ann Thorac Surg 1996;61:1239-40. 4. Filler RM, Forte V, Chait P. Tracheobronchial stenting for the treatment of airway obstruction. J Pediatr Surg 1998;33:304-11. 5. Park AH, MacDonald R, Forte V, et al. A novel approach to
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6. 7.
8.
9. 10.
tracheostomal collapse: the use of an endoluminal Palmaz stent. Int J Pediatr Otorhinolaryngol 1998;46:215-9. Jacobs JP, Quintessenza JA, Botero LM, et al. The role of airway stents in the management of pediatric tracheal, carinal, and bronchial disease. Eur J Cardiothoracic Surg 2000;18:505-12. Jones LM, Mair EA, Lyon RD, et al. Multidisciplinary airway stent team: a comprehensive approach and protocol for tracheobronchial stent treatment. Ann Otol Rhinol Laryngol 2000;109:889-98. Furman RH, Backer CL, Dunham ME, et al. The use of balloonexpandable metallic stents in the treatment of pediatric tracheomalacia and bronchomalacia. Arch Otolaryngol Head Neck Surg 1999;125:203-7. Nashef SA, Dromer C, Velly JF et al. Expanding wire stents in benign tracheobronchial disease: indications and complications. Ann Thorac Surg 1992;54:937-40. Cook CH, Bhattacharyya N, King DR. Aortobronchial fistula after expandable metal stent insertion for pediatric bronchomalacia, J Pediatr Surg 1998;33:1306-8.
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11. Urschel JD. Delayed massive hemoptysis after expandable bronchial stent placement. J Laparoendosc Adv Surg Tech A 1999;9:155-8. 12. Zakaluzny SA, Lane JD, Mair EA. Complications of tracheobronchial airway stents. Otolaryngol Head Neck Surg 2003;128:478-88. 13. Rafanan AL, Mehta AC. Interventional chest radiology: stenting of the tracheobronchial tree. Radiol Clin North Am 2000;38:395-408. 14. Hramiec JE, Hassler GB. Tracheal wire stent complications in malacia: implications of position and design. Ann Thorac Surg 1997;63:209-13. 15. Rousseau H, Dahan M, Lauque D et al. Self-expandable prostheses in the tracheobronchial tree. Radiology 1993;188:199-203. 16. Maeda K, Yasufuku M, Yamamoto T. A new approach to the treatment of congenital tracheal stenosis: balloon tracheoplasty and expandable metallic stenting. J Ped Surg 2001;36:1646-9.
OBJECTIVE: Our aim was to present our experience with complications caused by placement of metallic stents in the pediatric airway. DESIGN AND SETTING: We conducted a retrospective study of the medical records of patients with complications resulting from metallic stent placement, managed by the senior authors between 1993 and 2002. RESULTS: Nine children had complications associated with the placement of metallic airway stents. Of these, 8 children required stent removal. Granulation tissue and tracheal stenosis were seen in all 7 children with long standing stent placement. There was 1 stent death in this series. CONCLUSIONS: Metallic airway stents can cause significant complications in the pediatric airway. These complications may supersede the airway compromise that necessitated their initial placement. As such, metallic stent placement should be approached with caution. The likelihood and severity of complications increase with time, as do the difficulties encountered upon removal. The proportion of patients in whom metallic stents may be placed “permanently” without complications is not known. Therefore we recommend that metallic airway stents be considered a temporizing measure of limited duration. (Otolaryngol Head Neck Surg 2004;131:355-61.)
From the Division of Pediatric Otolaryngology/Head and Neck Surgery, Cincinnati Children’s Hospital Medical Center (Drs Lim, Cotton, and Rutter); the Department of Otolaryngology, University of Cincinnati College of Medicine (Dr Cotton and Rutter); the Aerodigestive and Sleep Center, Cincinnati Children’s Hospital Medical Center (Drs Cotton, Azizkhan, Wood, and Rutter); the Division of General and Thoracic Pediatric Surgery, Cincinnati Children’s Hospital Medical Center (Dr Azizkhan and Cohen); and the Division of Pulmonary Medicine Research, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH (Dr Wood). Presented at the Annual Meeting of the Academy of Otolaryngology–Head and Neck Surgery, Orlando, FL, September 21-24, 2003. Reprint requests: Michael J. Rutter, FRACS, Division of Pediatric Otolaryngology/Head and Neck Surgery, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229-3039; e-mail, mike. [email protected] 0194-5998/$30.00 Copyright © 2004 by the American Academy of Otolaryngology–Head and Neck Surgery Foundation, Inc. doi:10.1016/j.otohns.2004.04.007
MD,
ROBERT E. WOOD,
MD, PHD,
ALIZA P. COHEN,
MA,
and
I n recent years, metallic airway stents have become increasingly popular in the management of challenging tracheobronchial obstruction in the adult and pediatric airway. In most adults, stents are placed to alleviate intraluminal obstruction as a result of cicatrix formation or benign or malignant neoplasms. In children, however, they are usually placed to manage congenital or acquired tracheomalacia or tracheobronchomalacia. The overall preliminary success1-7 of these small, intriguing devices, together with the known drawbacks of traditional approaches, inspired receptivity and eagerness to attempt this novel approach. Reported advantages of metallic stents have included their relative ease of application, their availability in a wide range of sizes, and their putative ability to maintain mucociliary function. Additionally, in some patients, they can accommodate growth by being periodically dilated until they attain their maximum physical capacity.6,8 Although research has shown that judicious stent placement can alleviate major airway obstruction and provide life-saving airway improvement in many patients, studies and case reports continue to document serious and unsettling complications, particularly with longer-term stenting, that are increasingly tempering the initial enthusiasm.9-12 Most authors agree that removal of metallic stents can be perilous, especially after the stent has been in place for months or years and has completely epithelialized, or is so deeply embedded in the wall of the airway that it is not accessible.6,12,13 As such, in some patients, these devices have been considered permanent.6,8 In the first published study to focus on stent complications, Zakaluzny et al12 identified and analyzed complications from several types of stents in 9 patients (including 1 infant and 1 adolescent) who were treated for either benign or malignant tracheobronchial diseases. Results revealed that the most common complications included stent migration and fracture, granulation tissue formation around the stent, problems with mucociliary clearance, poor patient tolerance, and problems with placement and removal. These complications were found to occur more frequently in long-term treatment of benign conditions. In addition, in this study, our aim was to specifically focus on complications of metallic stents in the pediatric airway. We present our experience with 9 patients, 8 of whom required stent 355
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Table 1. Stent types, complications, and treatment
Patient no.
Type of stent
Stenosis
Airway obstruction/ granulation
1
Palmaz
⻬
⻬
2
Wallstent
⻬
⻬
3
Wallstent
⻬
⻬
4
Wallstent
⻬
⻬
5
Silicone-coated
⻬
⻬
6 7
Palmaz Wallstent
⻬
⻬
8
Palmaz
9
Palmaz
Fracture fragmentation
Erosion/ migration into adjacent structures
⻬
⻬
⻬ (iatrogenic)
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬
⻬ ⻬
⻬ (iatrogenic, bent stent)
Intraluminal exposure
Partial integration into airway wall
⻬ ⻬
⻬
⻬
⻬
⻬
⻬
Treatment Open and endoscopic stent removal (with cardiopulmonary bypass) Open stent removal with LTR Endoscopic removal of remnant wires and tracheal dilation Open stent removal and subsequent LTR Endoscopic stent removal Patient died Endoscopic stent removal Endoscopic stent removal Endoscopic stent removal
LTR, laryngotracheal reconstruction.
removal. Complications are outlined and airway management strategies are discussed. PATIENTS AND METHODS We reviewed the medical records of patients with complications resulting from metallic stent placement who were managed by the senior authors (M.J.R., R.G.A., R.T.C.) between 1993 and 2002. In patients 1 through 7, stents were placed by physicians in other institutions. In patients 8 and 9, stents were placed by one of the senior authors. The airway was assessed with regard to stent migration, granulation tissue formation, and stent-associated stenosis, and management strategies were documented. This study was approved by the Institutional Review Board of Cincinnati Children’s Hospital Medical Center, Cincinnati, OH. RESULTS The patients in series included 5 males and 4 females. These patients ranged in age from 1 month to 40 months at the time of stent placement. There was wide variation in the duration of stenting, ranging from 1 month in patient 8, to 5 years in patient 7. In 4 patients, congenital tracheobronchomalacia was the predominant airway problem necessitating stent placement. In 4
other patients, placement was performed for acquired tracheal and/or bronchial collapse or stenosis. In 1 patient, a stent was inserted as part of a surgical repair of complete tracheal rings. Palmaz stents (Johnson & Johnson International Systems Co., Warren, NJ) and Wallstents (Schneider Corp, Minneapolis, MN) were each inserted in 4 patients, whereas an experimental silicone-coated wire stent was inserted in 1 patient. Because our institution is a quaternary care referral center, our population comprised a highly select subgroup of patients with a wide spectrum of problems and complications. To illustrate the unique issues involved, we present below a detailed synopsis of these cases. A broad overview of our series is presented in Table 1. Patient 1 This female was born at 33 weeks’ gestation with VATER syndrome, requiring gastrostomy tube placement and repair of a tracheoesophageal fistula and esophageal atresia. Though discharged from hospital at 1 month of age, she was readmitted at 3 months with respiratory failure due to severe tracheobronchomalacia. An aortopexy was unsuccessful, requiring tracheotomy and continuous positive airway pressure (CPAP). At 16 months of age, de-
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cannulation was achieved with placement of 5 stents (Palmaz). One stent was inserted in each main stem bronchus, 2 in the trachea, and the fifth appears to have been inadvertently placed in a large tracheoesophageal fistula pouch. Ongoing problems with stent fracture and restenosis required removal and replacement of the bronchial stents twice over the next month. By the age of 18 months, tracheotomy and CPAP were required to alleviate life-threatening airway obstruction. By 35 months of age, life-threatening airway obstruction prompted referral to our institution. Assessment at that time showed fragmented stents in the trachea and both bronchi, with tracheal stenosis, tracheal and bronchial collapse, and a highly unstable airway. Because the child was thought to be at imminent risk of death, the stents were removed within 24 hours. Although most of the tracheal and right bronchial stents were endoscopically removed in a piecemeal fashion, the left bronchial stent required removal under cardiopulmonary bypass through an open bronchotomy. Acquired stenosis within the bronchus required placement of a pericardial patch. The fifth stent could not be located. One month later, severe left bronchomalacia (of a devitalized pericardial patch) required placement of a new Palmaz stent. The airway was stabilized following this surgery. Though the child remained tracheotomy-dependent, she was weaned off CPAP. At 52 months of age, severe dysphagia developed and was found to be caused by the fifth stent having eroded into the esophagus. This stent was removed endoscopically from the esophagus in a piecemeal fashion. Removal was an extremely difficult procedure, with damage to the esophageal wall. The esophageal stricture remained recalcitrant as a result of a single retained wire, which was removed at 57 months of age. Currently (at 72 months of age) the esophagus has a minimal asymptomatic stricture, and the trachea and bronchi have ongoing mild granulation, associated with wire remnants. These remnants will eventually require removal, as will the left bronchial stent. Patient 2 As a result of severe neonatal idiopathic hepatitis, this male infant required a liver transplant at the age of 11 months. A tracheotomy was placed 1 month later because of prolonged ventilatory requirements. He was decannulated at 30 months of age, and had a stomal closure at 33 months of age. Three weeks after stomal closure, airway compromise associated with tracheal stenosis at the stoma site required placement of a stent (Wallstent). Ongoing problems with granulation and stenosis required repeated laser intervention, steroid
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injections, and tracheal dilations. At 80 months of age, respiratory arrest prompted transfer to our institution. Evaluation revealed a grade 3 subglottic stenosis associated with the proximal end of the stent, intraluminal granulation tissue, and a mild stenosis associated with the distal end of the stent. A section of the distal stent was fully exposed in the airway, but 80% of the stent was fully mucosalized and the proximal end was deeply buried in scar tissue. A laryngotracheal reconstruction with anterior and posterior costal cartilage grafting was performed as a single-stage procedure, and the stent was completely removed in a piecemeal fashion. At 83 months of age, the airway was widely patent and the patient was asymptomatic. Patient 3 This male infant was diagnosed in utero with a severe right-sided congenital diaphragmatic hernia. He underwent fetal surgery at 26 weeks’ gestation, and a tracheal clip was placed. At 31 weeks’ gestation, an ex utero intrapartum treatment (EXIT) procedure was performed and the tracheal clip was removed. The neonatal period was unstable, and following repair of the diaphragmatic hernia extubation could not be achieved because of tracheal stenosis at the site of the tracheal clip placement. At 2 months of age, 2 stents (Wallstents) were placed, allowing extubation 1 week later. Because of persistent tracheal stenosis, the stents were removed at 27 months of age. Removal was accomplished through an open approach, and an anterior cartilage graft was inserted. Because of persistent stridor, the child was referred to our institution at 28 months of age. Evaluation revealed persistent severe tracheal stenosis associated with retained tracheal wires. These wires were removed endoscopically, and the area of stenosis was dilated and treated with mitomycin C. Though follow-up at 50 months of age showed minimal tracheal stenosis, the child was asymptomatic. Patient 4 This twin female was born at term with a double outlet right ventricle and pulmonic stenosis, requiring a right Blalock Taussig shunt at 10 days of age. At 6 months of age, she was noted to have intermittent episodes of tachypnea. At 16 months of age, a Rastelli cardiac repair required prolonged intubation. Extubation was achieved only after insertion of a wire stent (Wallstent) to manage tracheomalacia. By 18 months of age, subglottic stenosis had developed at the proximal end of the stent despite subglottic laser treatment. By 21 months, numerous emergent admissions to hospital for an unstable airway prompted transfer to our unit. Assessment at that time indicated a grade 3 subglottic
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stenosis associated with the proximal end of the stent, which was deeply embedded in scar tissue. The stent could not be removed endoscopically. To stabilize the airway, a tracheotomy was placed, with several wires being cut to allow placement of the tube. The stent was firmly adherent and could not be safely removed through the tracheotomy incision. By 24 months of age, bronchial compromise associated with granulation tissue formation at the lower end of the stent necessitated removal of the stent in an open procedure. This procedure was performed in the cardiac operating room where cardiopulmonary bypass facilities were readily available. Although stent removal was challenging and was performed in a piecemeal fashion, cardiopulmonary bypass was not required. Persistent grade 3 subglottic stenosis required laryngotracheal reconstruction at 30 months of age. Because of tracheomalacia, however, decannulation could not be achieved until 65 months of age. By 71 months of age, the patient was asymptomatic, without subglottic stenosis and with only mild tracheomalacia. Patient 5 This term female was born with esophageal atresia and a distal tracheal esophageal fistula, which were repaired during the neonatal period. Although she initially did well, between 6 and 9 months of age she had repeated life-threatening apneic episodes as a result of severe tracheomalacia involving 65% to 75% of the length of the trachea. A silicone-coated metallic stent (an experimental prototype for clinical study) was inserted and her apneic episodes ceased. Within 4 months, she began wheezing and showed signs of air trapping on chest x-ray. Upon referral, endoscopy revealed granulation tissue at the distal interface between the stent and the trachea at the level of the carina. This created a stenotic orifice to each main bronchus. The granulation tissue was endoscopically removed and the patient underwent 2 courses of systemic steroids, with recurrence of granulation tissue upon cessation of each course. Eight months after stent insertion, recurrent airway obstruction necessitated endoscopic stent removal. The stent was found to be frayed and wires protruded through the silicone coating into the tracheal wall and the lumen of the airway. Subsequent to stent removal, tracheomalacia was not as severe as it had been prior to stent insertion and the patient remained free of major symptoms. At age 7, this child remained asymptomatic. Patient 6 Stridor was noted in this 2.5-kg male infant immediately after delivery, but intubation with a standard tracheal tube was not was possible. Endoscopy and CT
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scan corroborated the presence of complete tracheal rings extending from just below the subglottic region of the larynx to the carina. An echocardiogram revealed a pulmonary artery sling. During the neonatal period, the patient underwent a repair of the tracheal stenosis and pulmonary artery sling under cardiopulmonary bypass. The anterior wall of the trachea was divided and a pericardial patch inserted. A stent (Palmaz) was placed to buttress the airway. Two weeks after this procedure, the stent eroded through the wall of the pericardial patch, causing mediastinitis, which was the ultimate cause of death. Postmortem examination showed that the distal portion of the stent had eroded into the pulmonary artery. Patient 7 This term male required a complete small bowel resection at 10 days of age following a volvulus. At 8 months of age, he required both small bowel and liver transplantation and long-term ventilatory support via tracheotomy. Though he was decannulated at 40 months, severe tracheomalacia necessitated stent placement. For the next 5 years, he had ongoing problems with the stent, requiring multiple laser procedures to remove granulation tissue. He was referred to our institute at 86 months of age with stridor and stentassociated stenosis. Pulmonary function testing revealed severe fixed airway obstruction. Endoscopic evaluation showed exuberant granulation tissue, stenosis, and a partly integrated stent (Wallstent), which was removed in a piecemeal fashion. Follow-up at 89 months of age showed that tracheal diameter was much improved. At this time, and at subsequent follow-ups, residual strands of wire were removed. At 92 months of age, the patient was asymptomatic with minimal tracheal narrowing, normal pulmonary function testing, and bronchoscopic improvement, however, residual wires remained. Patient 8 This term female was born with mild respiratory distress. At 10 months of age, increasing respiratory compromise prompted admission and investigation. A pulmonary artery sling was diagnosed and subsequently repaired under cardiopulmonary bypass. Severe postoperative respiratory compromise required placement on extracorporeal membrane oxygenation, and severe tracheal stenosis due to complete tracheal rings was diagnosed. A bovine pericardial patch was used to repair the trachea and mainstem bronchi. Following an episode of cardiopulmonary arrest at 13 months of age, a tracheotomy was placed. Distal tracheal collapse and granulation formation resulting in recurrent acute airway compromise required multiple bronchoscopies
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over the next 20 months, requiring this infant to spend much of her life in the hospital. She was transferred to our institution at 33 months of age. Assessment revealed a grade 4 upper tracheal stenosis at the stomal site and distal tracheal and bronchial stenosis and collapse. The mainstem bronchi were identified with great difficulty. The patient required a distal tracheoplasty and carinal reconstruction with a tracheal homograft replacing the anterior distal trachea and mainstem bronchi. Tracheal homografts usually require stenting, but silastic stents were too large to be accommodated, so the airway was maintained with a long tracheotomy tube and CPAP. An unstable postoperative course and left bronchial collapse required placement of a left bronchial stent (Palmaz) at 35 months of age, which we had planned to remove within 6 months. At 36 months, follow-up bronchoscopy at the referral hospital resulted in the stent being bent. Upon return to our institution, the proximal end of the stent was overlying the entrance to the left mainstem bronchus, allowing ventilation but precluding bronchoscopic evaluation. The stent was removed without difficulty. At a 44-month follow-up, the distal airway was widely patent. The patient was stable on room air without CPAP and with a short tracheotomy tube lying above the level of the homograft. We plan to proceed with reconstruction of the upper airway stenosis at 50 months of age to achieve decannulation. Patient 9 This male was born at 24 weeks’ gestation as a result of premature rupture of amniotic membranes, endometritis, and amnionitis. As a newborn, he required intubation and prolonged ventilation for severe respiratory distress syndrome, which led to bronchopulmonary dysplasia and chronic lung disease. A tracheobronchoscopy at 5 months of age showed severe tracheomalacia extending from the thoracic inlet to the carina, and involving both main and segmental bronchi. A tracheostomy was placed at this time. However, because of severe airway obstruction related to distal tracheobronchomalacia, stents were inserted in both main bronchi and in the distal half of the trachea. Although the patient showed initial improvement, circumferential obstructing granulation tissue created stenotic openings in both main bronchi. Upon referral, the patient was treated with a combination of balloon dilation to flatten the granulation tissue within the stent area and repeated courses of high-dose steroids, with recurrence of granulation tissue formation upon cessation of each course. After being in place for 5 months, 2 of the 3 stents were removed and the patient was managed with chronic ventilator support. The left bronchial stent had become
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incorporated into the bronchial wall and could not be safely removed; it was thus left in place. The patient died of progressive chronic lung disease at 18 months of age. DISCUSSION The placement of metallic stents was initially hailed as being a comparatively safe approach to achieving airway patency in children with tracheomalacia, tracheobronchomalacia, and a number of other specific airway conditions.1,3,4 Our experience over the past 9 years suggests that this approach carries significant risks and may be associated with major aerodigestive and vascular complications. These complications can occur during stent placement, over the period of time in which stents remain in the airway, and during the removal procedure. In light of these considerations, we rarely place metallic airway stents. This series represents only a fraction of the pediatric patients in whom metallic airway stents have been placed—the numerator being children with complications arising from stent placement and the denominator being those whose stents are asymptomatic or who have not been referred to our institute. Unfortunately, the size of the denominator is unknown, and we therefore cannot determine the overall complication rate. It is probable that in some children metallic stents may be tolerated indefinitely without complication, and therefore not warrant removal. However, the proportion of children in whom this is the case is unknown. Therefore, it is our opinion that the potential and severity of associated complications warrants limiting stent placement to patients in whom alternative approaches have failed or are contraindicated, and that they be placed with a view to eventual removal. In our routine practice, children with severe tracheomalacia are managed with aortopexy or placement of a tracheotomy tube that extends close to the carina. Those with severe tracheobronchomalacia are managed with tracheotomy and positive pressure support, either by CPAP, bilevel positive airway pressure, or ventilation. Another alternative is the use of Y tracheotomy tubes, though we have no experience with this technique. Though concerns about the use of these approaches are valid, problems that arise are generally easier to manage than those resulting from stent placement, and improvement of malacia with time is anticipated. The endoscopic evaluation of metallic stents must be carried out with caution, keeping in mind that instrumentation and manipulation when suctioning, replacing tracheal tubes, or performing endoscopic procedures may cause stent damage, fracture, or displacement. If
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subglottic or tracheal stenosis is present at either end of a stent in a child without a tracheotomy, bronchoscopy may induce edema and acute airway compromise. If fractured wires are present, they may protrude through the lumen and into the wall of the airway. During flexible bronchoscopy, these wires can “fish-hook” the bronchoscope, either damaging it or hampering its removal. We have found that the longer metallic stents are in situ, the greater the risk of complications and the more challenging the removal. In our series, there were only 2 children (patients 6 and 8) who had short-term stent placement and these were the only 2 who did not have stenosis, obstruction, granulation, or partial integration of the stent into the airway wall. Of the 7 patients with long-term stent placement, all had associated stenosis and granulation tissue, and 6 had partial integration of the stent into the airway wall. All of these complications have been previously reported, both in the adult and pediatric literature.4,9,12,14-16 Removal of long-standing metallic stents is complex, and achieving optimal outcomes requires the cooperative efforts of a team of pediatric subspecialists who are skilled in airway management and reconstruction. Dreaded complications that are perhaps underreported but that have been anecdotally discussed among clinicians include risks of tracheal tearing, lethal airway obstruction, and bleeding or erosion of the stent into a great vessel. Naschef9 likens the removal technique to that of “rolling spaghetti on a fork,” noting that it is “much more difficult and at least equally as messy.” The type of stent, the duration of stent placement, and the degree of integration and entrapment in the airway wall are all critical factors in determining and planning optimal approaches to stent removal. Palmaz stents consist of a heavy gauge tubular steel mesh, whereas Wallstents consist of many thin wires. The latter are thus more likely to be removed in many fragments. In general, the longer a stent has been in place, the more integrated into the airway wall it becomes, and the more difficult it is to remove. Visualization of the proximal end of the stent may allow for endoscopic removal, whereas a stent buried by a proximal stenosis effectively precludes endoscopic removal. In some cases, tracheoplasty or laryngotracheoplasty may be required at the time of stent removal. Endoscopic removal is best achieved by grasping the proximal end of the stent with an endoscopically guided alligator forceps, and, while steadying the shaft, rotating the forceps for several revolutions to wind the stent onto the jaws of the forceps (technique used in patients 1, 5, 7, 8, and 9). Once the forceps have been rotated, some force may still be required
to disengage the stent from the airway wall, and some wires may fracture and remain intraluminal. Because Palmaz stents have more structural integrity than Wallstents, they are more likely to be removed intact or in fewer fragments. In contrast, Wallstents may leave a nest of wires occluding the tracheal lumen. Though these wires may look unsettling, particularly to the anesthetist, they are flimsy, and a ventilating bronchoscope can be negotiated through them. Remnant wires are removed in a piecemeal fashion. There is inevitably some bleeding, but this is usually transient. Follow-up endoscopy within 1 week is recommended to evaluate mucosal healing. Open removal is indicated if there is stenosis burying the proximal end of the stent, if integration precludes safe endoscopic removal, or if laryngotracheal reconstruction is desired at the time of stent removal. Palmaz stents are best dissected free from the tracheal wall and then removed as a wire mass. Other stents usually require piecemeal removal. In some cases wire by wire removal may be advantageous in that each individual wire may slide out of a submucosal “tunnel,” leaving the mucosa intact. With open or endoscopic removal, remnant wire fragments may be retained. Although these fragments may be asymptomatic and not warrant further intervention, in some cases they may act as a nidus for further stenosis. In some patients, wire fragments continue to migrate and eventually protrude into the lumen of the airway or esophagus, thereby permitting subsequent endoscopic removal. CONCLUSIONS Metallic airway stents can cause significant complications in the pediatric airway. These complications may supersede the airway compromise that necessitated their initial placement. As such, metallic stent placement should be approached with caution. Removal of long-standing stents is challenging. When stent placement is required, we recommend that placement be considered a temporizing measure for a limited duration. REFERENCES 1. Mair EA, Parsons DS, Lally KP. Treatment of severe bronchomalacia with expanding endobronchial stent. Arch Otolaryngol Head Neck Surg 1990;116:1087-90. 2. Filler RM, Forte V, Fraga JC, et al. The use of expandable metallic airway stents for tracheobronchial obstruction in children. J Pediatr Surg 1995;30:1050-6. 3. Bousamra M, Tweddell SS, Wells RG, et. al. Wire stent for tracheomalacia in a five year old girl. Ann Thorac Surg 1996;61:1239-40. 4. Filler RM, Forte V, Chait P. Tracheobronchial stenting for the treatment of airway obstruction. J Pediatr Surg 1998;33:304-11. 5. Park AH, MacDonald R, Forte V, et al. A novel approach to
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6. 7.
8.
9. 10.
tracheostomal collapse: the use of an endoluminal Palmaz stent. Int J Pediatr Otorhinolaryngol 1998;46:215-9. Jacobs JP, Quintessenza JA, Botero LM, et al. The role of airway stents in the management of pediatric tracheal, carinal, and bronchial disease. Eur J Cardiothoracic Surg 2000;18:505-12. Jones LM, Mair EA, Lyon RD, et al. Multidisciplinary airway stent team: a comprehensive approach and protocol for tracheobronchial stent treatment. Ann Otol Rhinol Laryngol 2000;109:889-98. Furman RH, Backer CL, Dunham ME, et al. The use of balloonexpandable metallic stents in the treatment of pediatric tracheomalacia and bronchomalacia. Arch Otolaryngol Head Neck Surg 1999;125:203-7. Nashef SA, Dromer C, Velly JF et al. Expanding wire stents in benign tracheobronchial disease: indications and complications. Ann Thorac Surg 1992;54:937-40. Cook CH, Bhattacharyya N, King DR. Aortobronchial fistula after expandable metal stent insertion for pediatric bronchomalacia, J Pediatr Surg 1998;33:1306-8.
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11. Urschel JD. Delayed massive hemoptysis after expandable bronchial stent placement. J Laparoendosc Adv Surg Tech A 1999;9:155-8. 12. Zakaluzny SA, Lane JD, Mair EA. Complications of tracheobronchial airway stents. Otolaryngol Head Neck Surg 2003;128:478-88. 13. Rafanan AL, Mehta AC. Interventional chest radiology: stenting of the tracheobronchial tree. Radiol Clin North Am 2000;38:395-408. 14. Hramiec JE, Hassler GB. Tracheal wire stent complications in malacia: implications of position and design. Ann Thorac Surg 1997;63:209-13. 15. Rousseau H, Dahan M, Lauque D et al. Self-expandable prostheses in the tracheobronchial tree. Radiology 1993;188:199-203. 16. Maeda K, Yasufuku M, Yamamoto T. A new approach to the treatment of congenital tracheal stenosis: balloon tracheoplasty and expandable metallic stenting. J Ped Surg 2001;36:1646-9.