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(Chest. 2005;127:2106-2112.)
© 2005 American College of Chest Physicians

Endoscopic Removal of Metallic Airway Stents*

William Lunn, MD, FCCP; David Feller-Kopman, MD, FCCP; Momen Wahidi, MD; Simon Ashiku, MD; Robert Thurer, MD, FCCP and Armin Ernst, MD, FCCP

* From Interventional Pulmonology (Drs. Lunn, Feller-Kopman, Wahidi, and Ernst) and Thoracic Surgery (Drs. Ashiku and Thurer), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA.

Correspondence to: Armin Ernst, MD, FCCP, Director, Interventional Pulmonology, BIDMC, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215; e-mail: aernst{at}bidmc.harvard.edu


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Conclusions
 References
 
Background: Complications of metallic airway stents include granulation tissue formation, fracture of struts, migration, and mucous plugging. When these complications result in airway injury or obstruction, it may become necessary to remove the stent. There have been few reports detailing techniques and complications associated with endoscopic removal of metallic airway stents. We report our experience with endoscopic removal of 30 such stents over a 3-year period.

Methods: We conducted a retrospective review of 25 patients who underwent endoscopic stent removal from March 2001 to April 2004. The patients ranged in age from 17 to 80 years (mean, 56.3 years). There were 10 male and 15 female patients. The stents had been placed for nonmalignant disease in 20 patients (80%) and malignant disease in 5 patients (20%). All procedures were done under general anesthesia with a rigid bronchoscope. Special attention was focused on the technique of stent removal and postoperative complications.

Results: Thirty metallic airway stents were successfully removed from 25 consecutive patients over a 3-year period. The basic method of removal involved the steady application of traction to the stent with alligator forceps. In all cases, an instrument such as the barrel of the rigid bronchoscope or a Jackson dilator was employed to help separate the stent from the airway wall before removal was attempted. In some instances, the airway wall was pretreated with thermal energy prior to stent removal. Complications were as follows: retained stent pieces (n = 7), mucosal tear with bleeding (n = 4), reobstruction requiring temporary silicone stent placement (n = 14), need for postoperative mechanical ventilation (n = 6), and tension pneumothorax (n = 1).

Conclusions: Although metallic stents may be safely removed endoscopically, complications are common and must be anticipated. Other investigators have described airway obstruction and death as a result of attempted stent removal. Placement and removal of metallic airway stents should only be performed at centers that are prepared to deal with the potentially life-threatening complications.

Key Words: airway • airway injury • bronchoscopy • complications • respiratory failure • stenosis • stent


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Conclusions
 References
 
Metallic airway stents are inserted with increasing frequency in patients with benign and malignant airway stenosis.1234567891011121314 The advantages of these stents are as follows: ease of placement, good internal-to-external diameter ratio, and low incidence of stent migration.111315 The disadvantages of metallic airway stents include difficulty in extraction, tendency for stent fatigue and fracture, and ingrowth of stent with tumor or granulation tissue.1113151617

When patients experience complications from metallic stents that cause airway injury or obstruction, it may become necessary to remove the stent. Although the manufacturers recommend stent removal by open surgical resection, several investigators671214181920212223 have reported endoscopic removal in small series. Very few of these reports have described the method of stent removal and associated complications. We report our experience with endoscopic removal of metallic airway stents with a focus on technique of removal and associated complications.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Conclusions
 References
 
Patients
We conducted a retrospective review of endoscopic removal of 30 metallic airway stents in 25 consecutive patients referred from March 2001 to April 2004 to our Airway Center. Table 1 describes the patient characteristics. The patients ranged in age from 17 to 80 years (mean, 56.3 years). The mean duration of stenting was 163.7 days (range, 14 to 901 days). Twelve of the stents were located in the trachea (40%), while 18 stents were located in the mainstem bronchi (60%). The average number of procedures per patient required to remove the stents and deal with the immediate related complications was 2.6. The original indications for stent placement, detailed in Table 2 , were malignant airway stenosis in 5 patients (20%) and nonmalignant airway stenosis in 20 patients (80%). The indications for stent removal are depicted in Tables 3 and 4 , and include high-grade obstruction due to granulation tissue, stent migration, strut fractures, mucous plugging, and stent infection (Fig 1 ).


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  		Table 1. Patient Characteristics

 

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  		Table 2. Indications for Stent Placement

 

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  		Table 3. Indications for Stent Removal

 

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  		Table 4. Indication for Removal Based on Stent Size and Location*

 


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  		Figure 1. High-grade airway left mainstem obstruction due to granulation tissue and multiple fractured wires.

 
We did include one patient with a Polyflex stent (Boston Scientific; Natick, MA), which is a "hybrid" prosthesis consisting of a metallic skeleton fully coated in silicone. We included this patient because the stent behaved like a metallic stent, suffering from strut fractures that caused severe airway obstruction.

Technical Details
All patients first underwent diagnostic flexible bronchoscopy and airway CT scans prior to stent removal (Fig 2 ) This allowed for thorough preoperative planning through detailed assessment of the airway anatomy, the relationship of vascular structures to the airway wall, and the condition of the stent.2425 All patients underwent rigid bronchoscopy with jet ventilation through an "open-tube" technique for stent removal. The stents and airway walls were pretreated with thermal modalities in six patients: argon plasma coagulation (n = 5) and electrocautery (n = 1). This intervention was performed to decease the amount of granulation tissue. In eight patients, balloon dilatation of the airway and stent were performed prior to any manipulation in order to provide enough "working room" for the operator.



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  		Figure 2. Two-dimensional reconstruction of a CT scan performed on a patient with a right mainstem metallic stent. There is near-total obstructing tissue visible at the distal end with patent distal airways behind the airway occlusion. The stent is otherwise intact.

 
In all cases, the tip of the rigid bronchoscope was placed next to the proximal end of the stent. Next, the stent was carefully dissected from the airway wall with either the tip of the rigid scope, optical forceps, or Jackson dilators (Fig 3 ). The stent was then grasped with rigid alligator forceps, and the forceps were rotated to wrap the stent around the forceps. Gentle, steady traction was then applied until the entire stent, or part of the stent was removed. This approach was repeated if necessary until all stent fragments were removed or swelling prevented further work. The rigid scope was then advanced into the airway in order to maintain airway patency and tamponade any bleeding or swelling. All patients were kept in the hospital for observation for a minimum of 24 h after stent extraction.



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  		Figure 3. An occluding metal stent is being grasped with rigid forceps. When tightly grasped, the stent will be "rolled up" and torn off the mucosa.

 

   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Conclusions
 References
 
All 25 patients had successful endoscopic extraction of their stents. Eight of the 30 stents (27%) were removed in one piece, while the remaining 22 stents (73%) were removed piecemeal. In seven stent-removal procedures, retained pieces of stent were left behind because it was believed that the benefit of removal of the pieces was outweighed by the potential risk of injury. All patients were treated as inpatients with a mean hospital stay of 7.7 days (range, 1 to 52 days). Complications of stent removal are detailed in Table 5 . There were a total of 32 complications: retained stent (n = 7), mucosal tear with bleeding (n = 4), reobstruction requiring silicone stent placement (n = 14), need for postoperative mechanical ventilation (n = 6), and tension pneumothorax (n = 1). Thirty-one of the 32 complications (97%) occurred in patients with benign airway obstruction. The one complication that occurred in malignant disease was in a patient with carcinoma of the lung who required silicone stenting of a main bronchus due to reobstruction after metallic stent removal.


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  		Table 5. Complications of Stent Removal*

 
Three of the patients with mucosal tears were electively intubated after stent removal and observed in the ICU for 24 h. A massive hemoptysis developed after a vigorous cough on postoperative day 1 in one patient with an airway tear who was not electively intubated; this patient required intubation and mechanical ventilation. This patient was extubated after 72 h. The airway tears healed in all four patients without further corrective action.

One patient with postoperative tracheal swelling was electively intubated and was taken back to the operating theater the next day for a bronchoscopy to survey the airway. Significant swelling was still present, so a silicone stent was placed in the trachea that allowed immediate liberation from mechanical ventilation. This patient ultimately had stent removal and tracheal reconstruction surgery.

One patient experienced a perioperative pneumothorax believed to be due to positive pressure ventilation, which has been a well-described complication of jet ventilation.26272829 Tension physiology developed in this patient, who required a chest tube, intubation, and was observed in the ICU for 48 h.

Additionally, one patient, a young man with one functional lung, required the presence of a cardiovascular surgeon and a cardiopulmonary bypass (CPB) perfusion team in the operating theater during the stent removal in case the patient could not be ventilated. The surgeon had performed a femoral vascular exposure and was standing by as necessary to initiate CPB. This patient did not have respiratory distress during or following stent removal, the stent was removed in one piece, and CPB was not employed. The patient did have a mucosal tear with bleeding and was one of the three patients described above who were electively intubated after the procedure and observed in the ICU for 24 h.

The outcomes of the patients are depicted in Table 6 . There were no deaths, and there were no instances in which replacement with another metallic stent was necessary. Ten of the 25 patients (40%) did require silicone stenting of the airways. Four of these patients had two stents placed (trachea and left main bronchus) for tracheomalacia. These patients eventually underwent stent removal and tracheoplasty for correction. Six patients had one stent placed. One of these patients had subglottic stenosis and underwent stent removal and tracheal reconstruction. Another patient with subglottic stenosis was deemed a poor candidate for corrective surgery or long-term stenting, and underwent tracheotomy. One patient had lung cancer and underwent stent removal and curative pneumonectomy. One patient had fibrosing mediastinitis and required long-term stenting of the left main bronchus. One patient had a thoracic cage deformity and elected long-term stenting of the left main bronchus over corrective surgery. The final patient had radiation fibrosis from prior treatment for carcinoma of the lung and required placement of a Y-stent. Overall, of the 14 silicone stents placed in 10 patients, 11 stents (79%) were eventually removed and corrective surgery was performed.


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  		Table 6. Relationship of Duration of Stenting With Complications Upon Removal

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Conclusions
 References
 
Our study is the first to report endoscopic removal of metallic airway stents with a focus on techniques, complications, and outcomes, and to date the largest reported experience. Previous reports in the literature are observational, in which the authors reported their experience with metallic stents in general. The details provided as to the techniques employed for stent removal and the complications encountered varied widely from study to study. For example, Rousseau et al19 reported their experience in placing 74 metallic stents in 55 patients; regarding stent removal, they stated, "Two of these patients had to undergo extraction of the prosthesis, and there was one case of respiratory distress that was fatal." No further details were provided.

Nashef et al18 reported on their experience with placing 28 Gianturco stents (Cook Incorporated; Bloomington, IN) in 15 patients. They removed four of the stents endoscopically and described their method of removal in detail: "The removal technique is similar to that of rolling spaghetti on a fork, but much more difficult and at least equally messy. The procedure is therefore time-consuming and often hindered by the well-embedded barbs. Removal may have to be piecemeal, requiring several fractures of the stent."

Filler et al14 and Zakaluzny et al22 both described their methods of stent removal in detail. Filler et al14 reported their experience with 30 Palmaz stents (Cordis Corporation; Miami Lakes, FL) in children with nonmalignant airway obstruction. They removed 11 stents with a rigid bronchoscope employing a metal suction catheter to dissect the stents from the airway wall before extraction with forceps. Zakaluzny et al22 employed a rigid suspension laryngotracheoscope and used optical forceps to dissect the stent from the airway wall. Alligator forceps were then employed to grasp and extract the stent through the rigid scope while the scope was advanced further into the airway. Neither group provided detailed discussions of complications as a result of stent removal. Nevertheless, a review of the existing literature makes it clear that there have been serious complications as a result of metal stent extraction: need for restenting, respiratory failure, strut-induced tracheal puncture requiring thoracotomy, retained stent pieces, tracheotomy, and death. This has prompted some investigators15 to recommend that uncovered metallic stents should not be placed in the airways.

It is interesting to note that in our series, while uncovered stents accounted for 33% of the total number of stents, 29 of 32 complications (91%) occurred during removal of uncovered metal stents. This is intuitive since more of an uncovered stent may be incorporated into the airway wall, causing more damage to the mucosa when removing it. Moreover, we found that complications in general were more likely to occur the longer a stent had been in place (Table 6).

It has not been well described if the use of a flexible bronchoscope only is preferable to rigid endoscopy in the removal of metallic stents. In our opinion, the use of rigid endoscopy is preferred. It may be possible to remove some metallic stents early after their placement, but after prolonged presence in the airways and considering the significant number of severe complications encountered, the open-ventilating scope provides the safest approach to this problem.

The overwhelming majority (97%) of complications of stent removal occurred in patients with benign airway obstruction. While only 25% of the patients in our series had malignant disease, we believe that it is a salient point that the patients with benign disease had a higher rate of complications. It is generally acknowledged, even to the point of being printed by the manufacturers on the package inserts of their products, that metallic stents are not considered the first line of therapy for patients with benign airway obstruction. Indeed, in patients with nonmalignant airway obstruction, a metal stent should probably be used only if all else fails. It also important to notice in this context, that 15 of the 25 patients did not require any further intervention after stent removal, calling the primary indication for the original stent placement into question.

Given that metallic airway stents can be difficult or impossible to remove and that removal can be associated with serious complications, we wondered how many of the patients in our series should not have had metallic stents placed in the first place. After carefully reviewing the details of each case, we believe that alternative treatment was available in all patients with benign complications, as none of the patients required restenting with a metallic prosthesis. It is noteworthy that one patient who had a stent placed for malignancy was in fact a candidate for curative pneumonectomy instead. Table 7 describes selected patients and possible alternatives. We realize that this type of "after-the-fact" analysis is subjective. However, there are data that clearly support that corrective surgery done by physicians experienced in airway surgery can be curative in many cases.73031 Indeed, Grillo et al31 performed tracheal reconstruction for subglottic stenosis in 503 consecutive patients and reported achieving excellent or good results in 94% of patients with an overall operative mortality rate of 2.4%.


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  		Table 7. Patients in Whom Primary Metal Stenting May Not Have Been Indicated*

 
Given the serious complications that may develop in patients treated with metallic stents, it is important to carefully consider the indications for stenting, the treatment alternatives, and the risks of stenting, should it become necessary. This may best be done in centers with multidisciplinary teams and experience.


   Conclusions
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusions
References
 
Metallic stents may be removed endoscopically. Complications are common and must be anticipated by physicians at the outset of the procedure. Other investigators have reported airway obstruction and death as a result of attempted endoscopic metallic stent extraction. We believe that placement and removal of metallic airway stents should only be performed at centers that have a multidisciplinary airway team and are prepared to deal with the potentially life-threatening complications.


   Footnotes
 
Abbreviation: CPB = cardiopulmonary bypass

Received for publication July 28, 2004. Accepted for publication November 1, 2004.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusions
 References
 

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