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Address reprint requests to Sudish C. Murthy, MD, PhD, FACS, FCCP, Center for Major Airway Disease, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, 9500 Euclid Avenue, Building J4-1, Cleveland, OH 44195
Self-expanding metallic stents (SEMS) have gained widespread acceptance as a treatment for palliation malignant airway obstruction (MAO) in the terminally ill patient. Ease of deployment and excellent efficacy have allowed for rapid dissemination of SEMS. However, an unintended consequence has been the use SEMS as definitive treatment for benign tracheal stenosis, which also includes a unique cohort of patients with tracheomalacia and dynamic airway collapse. Unfortunately, patients with benign airway obstruction (BAO) often have lengthier projected lifespans than MAO patients, and consequently, live long enough to develop significant complications from SEMS. Complications from SEMS are frequently more difficult to treat than the index benign stenosis/malacia for which the patient was originally stented, and this has recently prompted government warnings about use of SEMS for BAO.
Complications associated with SEMS placement for BAO include in-stent stenosis, migration, stent fracture, biofilm formation, and rarely, airway fistulae. Of these, SEMS-related stenosis is most often encountered and presents a formidable change to palliate. Currently, 2 general types of SEMS exist, covered and uncovered. Although covered SEMS fracture, migrate, induce a biofilm, and fistulize, they are less likely to stenose simply because the interstices between stent wires are covered with a nonabsorbable sheath that invests much, if not all, of the SEMS. This synthetic covering prevents in-growth of granulation tissue and subsequent in-stent stenosis (although the ends of the stent can still become incorporated and granulate). Uncovered SEMS, although less likely to be plagued with biofilm and migration, have a much greater association with airway stenosis. Uncovered wires stimulate a vigorous inflammatory response, resulting in granulation tissue growth through the stent and incorporation of the stent wires into the airway wall (Fig. 1).
Once incorporated, extrication of SEMS using the built-in collapsing mechanism is not effective and attempting to persist along this avenue can lead to a high-grade, acute airway. Instead, 2 options exist to manage incorporated, uncovered SEMS where in-stent stenosis has become clinically relevant. A variety of endobronchial ablative therapies can be used to treat obstructing granulation tissue. Argon-plasma-coagulation (APC), cryotherapy, and microdebridement are slightly favored over laser ablation for stent disimpaction because they are less likely to fracture the stent, whereas the laser will melt nitinol struts. Mitomycin C and steroids can be applied as antiproliferative/antiinflammatory adjuncts in hopes of reducing granulation tissue regrowth, but are of questionable utility. The goal of this type of intervention is to restore stent patency, without SEMS removal. However, recurrent stent-related granulation tissue may mandate reintervention every 3-6 months and eventually will become refractory to ablative interventions. Moreover, these treatments themselves induce inflammation and stimulate granulation tissue and ultimately extend the airway injury.
The second, and preferred, option to manage granulation tissue in-growth and stent incorporation is endobronchial (or open) extraction.
The decision to proceed along this treatment pathway should be made in the context of multidisciplinary collaboration (general thoracic surgery, interventional pulmonary medicine, thoracic anesthesia). Every component of the team is critical, and it is unlikely that a successful outcome can be achieved without each. Tracheal resection (and removal of SEMS) has been performed in rare circumstances. However, because most tracheal SEMS are >4 cm long, the length of trachea involved usually exceeds that which can safely be reconstructed, particularly because the area of disease always extends beyond both proximal and distal ends of the stent.
General indications for SEMS extraction are recurrent in-stent stenosis, stent fracture, and stent-related fistula (tracheoesophageal). There should be a clear plan for airway reconstruction after SEMS removal, and this most commonly involves replacement with a Silastic prosthesis (T-tube or Dumon-type indwelling stent). Patients should always be counseled about the possibility of tracheostomy as well. Highlighted here is an endobronchial technique for extraction of an incorporated SEMS.
Two videos have been provided to help demonstrate both the pathology and advanced techniques for extraction of incorporate SEMS. Video 1 was created from a patient with an uncovered SEMS placed for long-segment tracheomalacia secondary to radiation injury. The patient was referred at 1 year following placement with intractable cough, wheeze and dyspnea. The video demonstrates SEMS failure and 3 different late complications: stent fracture, granulation tissue overgrowth, and unfortunately, development of tracheo-esophageal fistula (noted along the left side of the patients’ airway and likely induced by stent fracture).
Video 2 shows the bronchoscopic and surgical approach to extraction of a densely incorporated covered-SEMS. The indications for SEMS removal in this case were granulation tissue in-growth, dense incorporation and, gram-negative rod bacterial biofilm development. Because the stent was so deeply incorporated into the airway wall, open extraction through multilevel tracheotomy was required. In addition, real-time airway reconstruction with silastic prosthesis was necessary. Video 2 demonstrates rigid control of the airway (including pneumatic dilatation) followed by surgical exposure of the cervical tracheal, piece-meal SEMS extraction, and finally, T-Tube reconstruction.
Bronchoscopic extraction of incorporated SEMS is a formidable task. A multidisciplinary team is required and experience with bronchoscopic and open airway procedures is essential. The most common indication for SEMS removal is recurrent high-grade in-stent stenosis from granulation tissue in-growth through uncovered stents placed in patients with BAO. Bronchoscopic removal is the procedure of choice, although the limitations of the procedure should be understood. Tracheal resection for SEMS extraction is less often indicated and reserved for circumstances, such as fistula, and for the reconstruction phase. Advances in bronchoscopic techniques and instrumentation have now allowed for SEMS to be extracted with far less morbidity, and bronchoscopic extraction should be the new standard.
Two videos have been provided to help demonstrate both the pathology and the advanced techniques for extraction of incorporate SEMS. The first bronchoscopic video was created from a patient with an uncovered SEMS placed for long-segment tracheomalacia secondary to radiation injury. The patient was referred at 1 year following placement with intractable cough, wheeze, and dyspnea. The video demonstrates SEMS failure and 3 different late complications: stent fracture, granulation tissue overgrowth, and, unfortunately, development of tracheoesophageal fistula (noted along the left side of the patients' airway, likely induced by stent fracture).
The second video shows the bronchoscopic and surgical approach to extraction of a densely incorporated covered SEMS. The indications for SEMS removal in this case were granulation tissue in-growth, dense incorporation, and Gram-negative rod bacterial biofilm development. Because the stent was so deeply incorporated into the airway wall, open extraction through multilevel tracheotomy was required. In addition, real-time airway reconstruction with Silastic prosthesis was necessary. This video demonstrates rigid control of the airway (including pneumatic dilatation) followed by surgical exposure of the cervical tracheal, piece-meal SEMS extraction, and finally, T-tube reconstruction.
Removal of self-expandable metallic stents: is it possible?.