There was a significant prolonged Y-stent placement therapeutic effect in all but 1 patient. There was both a reduction in the procedure number performed and an increase in interval days between procedures for the 5 patients who tolerated their stent. The mean number of procedures before secondary carina Y-stent insertion was 15.6, but only 4.8 after Y-stent insertion. The mean interval number of days between procedures was 24.5 days before the Y-stent insertion and 85.8 days after the Y-stent insertion. There were no complications in any patients during Y-stent insertion (Fig. 2).
One patient required secondary carina Y-stent replacement after inadvertent Y-stent dislodgement during a follow-up surveillance bronchoscopy and symptomatic restenosis within 2 days. One patient had an initial Y-stent placed in the BI/RML/RLL, which was removed after a lobectomy was performed for RUL airway obliteration. After RUL lobectomy, a recurrent stenosis developed in the BI, requiring a new Y-stent in the BI/RML/RLL. Another patient had a Y-stent replaced in the same location after obstructing granulation tissue developed in the LUL limb. The granulation tissue was debulked and injected with steroids (triamcinolone acetonide 10%), and a replacement Y-stent with a longer LUL limb was deployed without granulation tissue recurrence. While this patient developed obstructing granulation tissue requiring stent revision, small-to-moderate amounts of asymptomatic nonobstructing granulation tissue developed in 4 of the 6 patients. This granulation tissue was detected by routine surveillance bronchoscopy at 2- to 3-month intervals and was easily removed with standard biopsy forceps without stent revision or removal.
Only 1 of the 6 patients had a successful Y-stent removal without TBS recurrence. As presented above, 1 patient did not tolerate 2 different Y-stents within days because of a robust granulation response and another management approach was required. One patient had a Y-stent removal trial and failed, and was eventually retransplanted for a combination of TBS and chronic rejection. Another patient had a lobectomy with Y-stent removal, and a new Y-stent was placed for a new TBS. Two patients have not had a Y-stent removal trial and both are asymptomatic with stable spirometry.
Post–lung-TBS can be a devastating complication for lung transplant recipients that can lead to reduced lung function, multiple procedures with complex airway interventions, reduced quality of life, and potentially increased mortality. Current treatment strategies include balloon bronchoplasty, stent placement, reconstructive surgery, and retransplantation. Balloon bronchoplasty can be successful, but the result is often temporary with restenosis common.5,9 Surgical reconstruction is particularly risky in this patient population because of mmunosuppression, poor wound healing, postsurgical adhesions, and poor pulmonary reserves. Therefore, endobronchial airway stents form the backbone to prevent TBS recurrence and maintain airway patency.
In TBS, airway stenting has many anatomic constraints that prevent effective stent deployment. The TBS position and extension into donor airways determines what type of stent may be optimal in a given anatomic location. As the donor lung bronchial circulation is not reestablished, the donor airway is kept as short as possible to minimize airway ischemia. This often results in the RUL airway or the left hilum being within several millimeters of the anastamosis. If a pure anastamotic stenosis develops with normal distal airways, deployment and maintenance of stent position without migration or coverage of any distal airways can be problematic. If the stenosis extends further into the donor airways beyond the anastamosis, these anatomic relationships and optimal stent choice, placement, and maintenance become even more difficult to rectify.
Our original approach before 2005 was to place an uncovered SEMS across the TBS, which would rarely migrate, would allow aeration of donor airways (RUL or LUL) through the SEMS struts, and would effectively improve patient symptoms and spirometry. Unfortunately, in some patients, a robust granulation response would develop leading to further interventions and complications.10 Because of these SEMS complications and the 2005 Food and Drug Administration black box warning regarding SEMS in benign disease, this approach was abandoned in favor of silicone tube stent placement.
All of the patients in this case series underwent standard balloon bronchoplasty, TBS electrocautery incision, intrastenosis steroid injection, and/or deployment of other silicone endobronchial stents without the ability to maintain airway patency. Therefore, secondary carina Y-stent placement was conceived out of necessity in these patients after approaches and standard silicone tube stent deployment failed either because of the inability of the stent to remain in position or because of TBS extension into distal airways where tube stent configuration would not be feasible. We demonstrate here that secondary carina Y-stent deployment significantly decreased the number of procedures and increased the time between procedures for 5 of our 6 patients and stabilized their airways. Furthermore, the secondary carina Y-stents did not become dislodged as did silicone tube stents in several patients. The 3-limb Y-stent configuration not only provided a better anchor and positional stability, but also offered the ability to stent multiple adjacent TBS areas.
Our data also demonstrate that there is no perfect stent for any application. One patient developed rapid and robust granulation tissue within days of Y-stent placement precluding successful secondary carina Y-stent utilization. In addition, a second patient developed obstructing granulation tissue 5 months after Y-stent placement that required granulation tissue debulking and deployment of a new Y-stent with a modified limb to prevent granulation tissue formation. The remaining 4 patients all developed small-to-moderate amounts of asymptomatic nonobstructing granulation tissue easily removed during surveillance bronchoscopy. These findings demonstrate that there is a role for surveillance bronchoscopy in these patients to ensure no stent-related complications are developing. Moreover, mucoid obstruction of silicone stents is a concern, which can lead to respiratory distress, especially in a single-lung transplant patient whose native lung is often severely compromised. However, we encountered no mucoid impactions through mucolytic medication nebulizers 3 times daily in all patients. Although it was technically more difficult to place secondary carina Y-stents compared with its initial design for the trachea and mainstem airways, this was not prohibitive and was performed safely with no procedural complications. Other investigators have described using silicone Y-stents safely in the secondary carina for malignancy.11
We arbitrarily chose approximately 1 year for Y-stent removal without any specific criteria other than clinical stability. In previously published data, there have been other SEMS and silicone tube stent series that were removed in this time frame without TBS recurrence. Thistlethwaite et al12 described their experience with silicone stent removal in a series of 22 stents placed for TBS: 18 were successfully removed in about 12 months (mean duration, 362.3 d; range, 185 to 567 d). In our patient series, only 1 of our 6 patients had their Y-stent removed without TBS recurrence. This patient had a grade II injury, which may be a factor in successful stent removal as the degree of airway injury and stenosis is less extensive. Three patients developed restenosis and required Y-stent reinsertion, and each of these patients presented with a grade IV anastamotic injury (extensive bronchial wall necrosis extending 2 cm from anastomosis) and type IV stenosis (diffuse bronchial stenosis). Similarly, Thistlethwaite et al describe difficulties with permanent stent removal in diffuse bronchial stenosis (type IV). Consequently, the degree and type of injury before stent placement may predict successful remodeling and stent removal. A larger study will be needed to further examine this observation.
Our study has several limitations; the most obvious is its retrospective nature and the potential bias by the investigators determining the frequency of subsequent interventions. However, there is no evidence-based protocol on the threshold for bronchoscopy in TBS management or bronchoscopic maintenance for any airway stent. Another limitation is that there were no objective measures (spirometry) or validated quality-of-life evaluations before/after Y-stent placement. We conjectured that the decrease in flexible and rigid bronchoscopies after our intervention translated into a meaningful quality-of-life improvement. Future prospective studies need to consider these limitations in their design.
To our knowledge, this is the first description of using the silicone Y-stent in the secondary carina for post–lung-transplant TBS. A combination of the unique anatomic anatamosis and airway configurations with the type and degree of stenosis lends to a secondary carina Y-stent offering a novel intervention for select patients. When the Y-stents were tolerated, they reduced the number of therapeutic procedures required to manage TBS and increased the interval between procedures after stent placement.
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Keywords:© 2012 Lippincott Williams & Wilkins, Inc.
bronchial stenosis; lung transplant; Y-stent