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Editorials

The When, the How and the Why of Metallic Stent Removal

Murgu, Septimiu MD; Stoy, Sean MD

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Journal of Bronchology & Interventional Pulmonology: October 2016 - Volume 23 - Issue 4 - p 266-271
doi: 10.1097/LBR.0000000000000341
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Self-expandable metal stents (SEMS) insertion can benefit patients with malignant airway obstruction.1,2 For benign disease, however, due to major long-term complications, in 2005 the Food and Drug Administration advised against the routine use of SEMS available on the market at that time, unless all other treatment options were contraindicated or not feasible.3 Despite this warning, SEMS continued to be inserted in patients with benign airway obstruction.4 As a result, since the Food and Drug Administration advisory, there have been several published reports that highlight the indications, techniques and outcomes of SEMS removal.

The case series by Simoff et al5 in this issue of the Journal is relevant for interventional bronchoscopists as it reiterates key factors related to indications for SEMS removal, techniques, anesthesia methods, and complications. Similar to prior SEMS removal publications, this is a single center retrospective study. Over the course of 10 years a total of 19 SEMS (15 covered and 4 uncovered) were removed during 16 different procedures in a total of 14 patients; 9 stents had been placed for malignant and 10 for benign airway obstruction. Eighteen stents were removed under general anesthesia utilizing rigid bronchoscopy. The majority of stents had some degree of endothelialization; in those cases a neodymium:yttrium-aluminum-garnet (Nd:YAG) laser was used before stent mobilization and retrieval with forceps. The study clearly describes a technique for SEMS removal and suggests the safety in the use of Nd:YAG laser for tissue photodessication of endothelialized SEMS. The overall complication rate associated with SEMS removal was reported as low, although significant complications occurred in 18.75% of the patients. In this study, 52% of stents were removed due to migration, a situation in which procedural complications are less likely—a stent that has migrated is unlikely to be embedded or obstructed by granulation tissue. The report by Simoff and colleagues reinforces adds to the limited body of published literature regarding SEMS removal.

As of this writing, experts in the field have provided recommendations, but there are no guidelines or consensus statements related to anesthesia, techniques, timing of removal or factors predicting SEMS removal–related complications. In this editorial we summarize the relevant case series published since 2005 that report on outcomes of bronchoscopic SEMS removal (Table 1). A remarkable finding of our analysis is a lack of standardization for reporting complications. In addition, there is a wide spectrum of defined complications—authors variably report unsuccessful removal, stent fracture, mucosal tears, airway hemorrhage, intensive care unit admission, respiratory failure, and death. Although actual complication rates are difficult to determine from the published studies, factors seem to predict SEMS removal–related complications:

TABLE 1
TABLE 1:
Table of Evidence Summarizing Original Research Articles on Metallic Stent Removal For Years 2006–2016
  • Type of SEMS: uncovered SEMS have a higher removal complication rate than covered ones due to tumor ingrowth, granulation tissue or endothelialization (Fig. 1). A few studies differentiate or report SEMS type-specific complications (Table 1). Lunn et al’s10 report shows that uncovered stent removal was associated with a much higher complication rate. Wang et al7 and Chan et al’s9 reports revealed a higher rate of unsuccessful stent retrieval of uncovered versus covered stents. Stent fracture during removal is more common with uncovered SEMS,7 likely due to stent embedding and/or granulation tissue. In the study at hand by Simoff and colleagues, approximately 20% of stents removed were uncovered, but these authors report no complications with their removal.
  • Duration of indwelling SEMS: SEMS removal–related complications rate increases with the duration of stent placement.4,10 Alazemi et al4 noted no major complications in SEMS that were removed within 30 days of insertion, while Lunn et al10 found that complications related to SEMS removal increased for every additional month they had been in place (Table 1). The study by Simoff and colleagues reveals a removal-related major complication rate of 16.7% for SEMS in place less than 60 days and 25% for stents that were in place for more than 60 days.
  • Initial indication for SEMS placement: SEMS removal–related complications are more common when stents were placed for benign disease.4,10 The reasons for more frequent complications in benign disease are not always clearly articulated in published reports, but are likely related to longer survival and thus more time for: embedding in the airway wall, granulation tissue formation, stent fatigue and fracture.
FIGURE 1
FIGURE 1:
Self-expandable metal stents related complications in a patient who had 2 uncovered self-expandable metal stents (trachea and left mainstem bronchus) inserted for severe postpneumonectomy tracheobronchomalacia. A, Granulation tissue partially obstructing the proximal aspect of the tracheal stent. B, Fractured wires and endothelialization (stent embedding in the airway wall). C, Neodymium:yttrium-aluminum-garnet laser-assisted photocoagulation of the granulation tissue. D, Silicone stent insertion inside the fractured and embedded airway stent restores airway patency.

In regards to SEMS removal, based on the available published evidence and clinical experience we suggest the following:

  • Uncovered SEMS should not be inserted for histologically benign processes. If a SEMS must be placed for benign airway disease (ie, surgery or silicone stent insertion not possible), then a covered SEMS should be chosen. Short-term bronchoscopic follow-up is warranted and SEMS removal should be performed if complications are identified.
  • Duration of stent insertion should be carefully considered before removal—a protracted stent requires caution when considering its removal due to increased risk for complications. Adjuvant technologies such as Nd:YAG laser, electrocautery or cryotherapy should be available to remove the granulation tissue before SEMS removal.
  • A pre-SEMS removal inspection flexible bronchoscopy and chest computed tomography are warranted for a thorough preoperative planning; these allow a detailed assessment of the airway anatomy, the relationship of vascular structures to the airway wall, and the condition of the stent.
  • Rigid bronchoscopic approach should be used for SEMS removal. Although flexible bronchoscopy has been reported,5,6,7,9 and some studies even report a fluoroscopic method,12,13 based on most published literature and our experience, we believe that a rigid bronchoscopic technique is preferred whenever possible. This allows operators to immediately intervene in case of airway hemorrhage or when reobstruction occurs poststent removal; in addition the instruments available for granulation tissue and stent removal are likely more efficient than flexible bronchoscopic techniques.
  • A completely or nearly completely embedded SEMS should probably be left in place and airway obstruction palliated with alternative techniques (ablative therapy with electrocautery and laser for granulation tissue) and/or coverage with an indwelling silicone stent (Fig. 1). Although not ideal, this is a palliative alternative to SEMS removal when the anticipated removal-related complications (airway perforation and massive hemoptysis) outweigh the benefits of SEMS removal.
  • Repeated interventions may be necessary for complete stent removal: in one series that reports this variable, the average number of procedures per patient required to remove the stents and address the immediate-related complications was 2.6.10 Staged removal procedures are likely warranted in patients with a high degree of obstruction from granulation tissue and in patients with SEMS embedded in the airway wall.

We suggest that interventional bronchoscopy community adopts a standardized procedural documentation for SEMS removal. In our opinion, documentation should contain the type of the stent removed (covered, partially covered, uncovered), its size (length, diameter), indication for initial stent placement, stent duration, removal indication, granulation tissue removal methods, and periprocedural complications—which should include: stent fracture/piecemeal removal, retained stent fragments/incomplete extraction, failure of extraction, bleeding events requiring intervention, mucosal tears, pneumothorax, pneumomediastinum, laryngeal edema, reobstruction requiring stent reinsertion, respiratory failure, intensive care unit admission, and death. Standardized documentation will allow bronchoscopists to perform meaningful research related to SEMS removal, compare the safety of various stents and better define operator-related, device-related and patient-related factors that predict SEMS removal complications.

REFERENCES

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