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Ann Thorac Surg 2006;82:274-278
© 2006 The Society of Thoracic Surgeons

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Original article: General thoracic

Do Expandable Metallic Airway Stents Have a Role in the Management of Patients With Benign Tracheobronchial Disease?

Department of Cardiothoracic Surgery, St. George's Hospital, London, United Kingdom

Accepted for publication February 9, 2006.

^_* Address correspondence to Dr Madden, Cardiothoracic Department, Atkinson Morley Wing, St. George's Hospital, Blackshaw Rd, Tooting, London, SW17 0QT, UK (Email: brendan.madden{at}stgeorges.nhs.uk).

	Abstract

Top Abstract Introduction Patients and Methods Results Comment References

 
BACKGROUND: With increasing availability many centers are deploying expandable metallic stents to manage patients with diverse endobronchial disorders. Although these devices have an important role in malignant disease their usefulness in benign large airway disorders is less defined.

METHODS: Between 1997 and 2005, 31 patients aged 34 to 83 years with benign large airway compromise secondary to tracheomalacia (n = 7), posttracheostomy stricture (n = 8), posttracheostomy rupture (n = 2), postpneumonectomy bronchopleural fistula (n = 2), stricture after lung transplantation (n = 3), lobectomy, tuberculosis, traumatic injury to right main bronchus (n = 1 patient each), and external compression of the airway secondary to achalasia, multinodular goiter, aortic aneurysm, right brachiocephalic artery aneurysm, right interrupted aortic arch, and dissecting aneurysm (n = 1 patient each) who were medically unfit for formal surgical intervention were treated by Ultraflex stent deployment. The range of follow-up was 1 week to 96 months. Stents were deployed under anesthesia using rigid bronchoscopy.

RESULTS: Complications included granulation tissue formation (n = 11) treated with Nd: YAG laser ablation, stent migration (n = 1; stent removed, another deployed), metal fatigue (n = 1), stent removal (n = 1), mucus plugging (n = 2), and halitosis (n = 6) difficult to treat despite antibiotics. Thirteen patients died of unrelated causes between 1 week and 15 months after stent deployment.

CONCLUSIONS: Endobronchial metallic stents should be considered only for selected patients with large airway compromise secondary to benign airway diseases for whom other medical comorbidities contraindicate formal airway surgery. Once deployed, they are difficult to remove, are associated with significant complications, and require prospective bronchoscopic surveillance and often further therapeutic intervention.

	Introduction

Top Abstract Introduction Patients and Methods Results Comment References

 
Tracheobronchial stents are useful in the management of large airway obstruction secondary to malignant disease. Improvements in stent design and in techniques of interventional bronchoscopy in recent years have extended the use of endoscopically deployed expandable metallic airway stents for benign airway disorders [1]. These devices are associated with symptom relief as well as improvements in respiratory physiologic outcomes in the short term [2–5] and may be a useful alternative for patients whose comorbidities render them unsuitable candidates for formal surgical intervention.

The long-term outcome after deployment of these stents for patients with benign airway diseases is unclear. Reported complications include obstructing granulation tissue formation, mucus plugging, recurrent respiratory infections, stent migration, metal fatigue, and fracture [6, 7]. Furthermore, once deployed these stents are very difficult to remove. We are concerned about the widespread use of expandable metallic stents in patients with benign airway disorders and report our medium-term experience of 31 patients for whom expandable metallic stents were deployed to address nonmalignant conditions causing large airway compromise. We believe that patients with benign airways disease must be carefully selected for stent deployment and should only be offered this form of treatment when formal surgical intervention is not appropriate on account of other medical comorbidities.

	Patients and Methods

Top Abstract Introduction Patients and Methods Results Comment References

 
Patients were referred to the Cardiothoracic Unit at St. George's Hospital, London, for assessment and management of large airway compromise. After multidisciplinary assessment with input from specialists in cardiothoracic surgery, cardiothoracic medicine, anesthesia, and pulmonology, surgical correction of the airway defect was not considered technically feasible or was contraindicated because of medical comorbidities. Each patient or an appropriate adult on his or her behalf gave fully informed written consent for the procedure. The hospital ethics committee chairman and the local audit committee provided approval for this retrospective study and the inclusion of the patient's detail contained therein. All patients had rigid and flexible bronchoscopy under general anesthesia. Luminal patency was improved by either bougie dilatation or application of Nd: YAG laser before deployment of Ultraflex expandable metallic stents (Boston Scientific, Watertown, MA) to the affected airway, as has been reported elsewhere [8]. Correct positioning of the stent was confirmed by direct visualization with a flexible bronchoscope at the time of the procedure and subsequently by chest radiograph. All patients received ciprofloxacin (500 mg twice daily by mouth) for 5 days after stent placement, which we considered to be a reasonable prophylaxis after the procedure. The median time for the procedure was 10 minutes.

We appreciate that expandable metallic stents can be deployed using fiberoptic bronchoscopy. However, in our unit we insert these stents using rigid bronchoscopy and are comfortable with this approach. Given the serious nature of our patients' medical comorbidities, and particularly for those patients in intensive care, their poor cardiorespiratory reserve increased the risk of stent deployment using flexible bronchoscopy in our judgment.

Between March 1997 and July 2005, we deployed 125 Ultraflex stents (65 tracheal, 60 bronchial) in 77 patients with malignant disease and 31 patients with benign airway disorders. The benign disorders consisted of posttracheostomy stricture (n = 8), tracheomalacia (n = 7), anastomotic stricture complicating lung transplantation (n = 3), iatrogenic tracheal tear after tracheostomy (n = 2), postpneumonectomy bronchopleural fistula (n = 2), strictures complicating lobectomy (n = 1), tuberculosis (n = 1), traumatic injury to the right main bronchus (n = 1), and external compression of the airway associated with achalasia, multinodular goiter, aortic aneurysm, right brachiocephalic artery aneurysm, right interrupted aortic arch, and dissecting aortic aneurysm in 1 patient each (Table 1). Twenty-five covered and six uncovered metallic stents were deployed for defects involving the trachea (n = 21), left main bronchus (5 patients), and right main bronchus (3 patients). Stents were deployed from the trachea to the remaining main bronchus in 2 patients to address bronchopleural fistula after pneumonectomy [9]. The median age of our patients was 60 years (range, 34 to 83 years), and the median follow-up period was 12 months (range, 1 week to 96 months). Twenty patients had stents deployed in the intensive care unit.

Surveillance bronchoscopies were performed during the first 6 months after stent insertion, and thereafter as clinically indicated. We performed surveillance bronchoscopies because we wished to carefully document postdeployment complications. Furthermore, given the degree of airway compromise before stent deployment we were concerned that airway complications could be well established before patients reported them to us. Granulation tissue formation was documented and when necessary, ablated using Nd: YAG laser therapy applied by means of a flexible bronchoscope. Details of the type of stent used, the date, site, and indication for stenting as well as any additional interventions on subsequent bronchoscopies were obtained from patients' hospital inpatient records and audited retrospectively. Data are listed as median values (range) of the study population and analyzed using Microsoft Excel 2000 software (Microsoft Corp, Redmond, WA).

	Results

Top Abstract Introduction Patients and Methods Results Comment References

 
Complications occurred in 15 patients (48%) and are listed in Table 2. These were granulation tissue formation (n = 11), halitosis (n = 6), mucus plugging (n = 2), stent metal fatigue (n = 1), and stent migration (n = 1). Some patients experienced more than one complication. Granulation tissue was successfully cleared using Nd: YAG laser therapy. Each patient with this complication received three treatments of Nd: YAG laser ablation, but one required five treatments. None of the stents was damaged by Nd: YAG laser therapy.

Six patients had problematic halitosis. Extensive investigations including microbiologic culture, barium swallow, and thoracic computed tomography did not identify an obvious cause. Pseudomonas aeruginosa was identified in 2 patients but despite prolonged courses of systemic and nebulized antibiotics, halitosis persisted. Interestingly, for 1 patient who was persistently culture negative, halitosis responded to oral doxycycline (patient 31).

One patient experienced stent metal fatigue at 36 months and had the stent removed without complication at rigid bronchoscopy, using rigid forceps under general anesthesia (patient 13). The stent had originally been deployed to treat an iatrogenic tracheal tear during percutaneous tracheostomy. At removal it was noted that the tracheal defect had sealed and therefore a further stent was not deployed. However, the airway was grossly abnormal and distorted as a result of granulation tissue proliferation around the outside of the cover and through the uncovered end of the stent. Fortunately, bronchoscopy 6 months after removal showed significant improvement, and the patient remains well at 1 year's follow-up. Stent migration occurred in 1 patient; the stent was initially repositioned but as further migration occurred, it was removed and a larger stent was deployed (patient 15). The airway looked normal. Further migration has not occurred during the subsequent 18 months. A proximal stricture occurred in 1 patient who had a stent deployed for tracheomalacia (patient 25); a second stent was deployed and successfully restored airway patency.

As regards our reviewing survival related to cause, one must bear in mind that our numbers are small and thus interpretation must be made with caution. Nevertheless, all 3 patients with an anastomotic stricture after lung transplantation are alive, although each patient had one or more complications. Undoubtedly these patients require careful long-term surveillance, but despite their immunosuppression, 2 patients experienced granulation tissue formation, although recurrent respiratory infection was not a problem. Both patients with a bronchopleural fistula subsequently died, 1 as a result of sepsis (patient 11) in intensive care and one 6 months after deployment as a result of a myocardial infarction. One patient (patient 13) with a posttracheostomy tracheal rupture remains well, and the stent has been removed without complication. However, the other patient had pneumonia and multiple organ dysfunction at the time of stent deployment and was in intensive care. She died 2 weeks later as a result of multiple organ failure.

Eight patients had tracheal stenting for stricture formation after tracheostomy. Six of these patients are currently alive, although complications occurred in 4 patients. One patient (patient 12) died 12 months after stent insertion as a result of complications related to her known acquired immune deficiency syndrome. The other patient (patient 19) had multiple organ dysfunction in intensive care and died 6 days after stent insertion. Two of the 3 patients stented for bronchial strictures are alive; both patients experienced complications related to the stent. One patient (patient 23) died 3 months later in a road traffic accident.

Seven patients had a tracheal stent inserted to address tracheomalacia. Three of these patients are currently alive; all experienced one or more complications after deployment, and 4 patients died. Two of these patients (patients 27 and 29) died in the intensive care unit of multiple organ failure. One patient (patient 28) died at 4 months as a result of a myocardial infarction, and 1 (patient 26) died at 1 month as a result of an intracerebral bleed.

Six patients received stents for extrinsic airway compression, and 3 of these patients are alive. One patient (patient 1) died of a cerebrovascular accident, 1 (patient 2) died of a myocardial infarction, and 1 (patient 5) died of pneumococcal pneumonia. Two of the patients in this group did not encounter problems with the stent (patients 3 and 6).

Thirteen patients died, and 5 of these deaths occurred in the intensive care unit. The median life expectancy of the patients who died after stent insertion was 1 month (range, 1 week to 15 months), although none of the deaths were directly attributable to stent insertion. The median age and follow-up period of the 18 surviving patients were 59 years (range, 34 to 77 years) and 22 months (range, 0.5 to 96 months), respectively. Four patients remain asymptomatic and have not experienced any stent-related complications.

	Comment

Top Abstract Introduction Patients and Methods Results Comment References

 
Defects of the large airway attributable to benign airway disease can be difficult to treat and have traditionally required formal surgical intervention. However, this may not be a suitable option for a proportion of patients who have multiple medical comorbidities as in our patients.

Patients who experience tracheal stenosis after tracheostomy have been successfully weaned from mechanical ventilatory support after tracheal stent insertion [3]. The development of airway stents with better design, as well as improvements in the techniques of bronchoscopy, have invariably led to an increase in the use of these devices for a variety of tracheobronchial disorders during the past decade [4, 10–12]. These devices are better tolerated by patients, and often lead to immediate relief of their respiratory symptoms. Furthermore, the ability to deploy expandable metallic stents using a flexible bronchoscope has meant that patients who would otherwise not tolerate surgical correction of large airway defects because of advanced age or medical comorbidities may in theory benefit both symptomatically and functionally from the use of such devices.

During the past 8 years, we have deployed expandable metallic stents for a variety of benign tracheobronchial conditions in 31 patients. Early improvement after stent insertion was noted, and there were no procedural-related deaths. We believe the favorable early outcomes from this series can be attributable to careful patient selection and expedient management of their airway problems by a multidisciplinary team with expertise in large airway management. Although 13 deaths were observed in our series, 12 of these patients were intubated and required intensive care support at the time of stent deployment; moreover, 7 patients were successfully extubated after stent placement but 5 patients died while in the intensive care unit. However, unlike the other 7 patients, the 5 patients who died in intensive care had multiple organ dysfunction at the time of deployment.

Although bearing in mind the small numbers in each group and the importance of not overinterpreting our data, we noted some potentially interesting trends. All 3 patients who had post–lung transplant anastomotic stricture survived. Aside from reduction in lung function, none of these patients were acutely unwell at the time of stent deployment. Six of the 8 patients stented for a tracheal stricture are alive, but only 3 of the 7 patients for whom stents were deployed to address tracheomalacia have survived. One patient in the former group and 2 patients in the latter group had multiple organ dysfunction at the time of stent insertion and subsequently died. Both patients with a bronchopleural fistula died, 1 of these as a result of sepsis in intensive care. Two of 3 patients with other forms of bronchial stricture who received stents survived. Aside from reduced lung function, none of these patients were acutely unwell at the time of stent deployment. Three of the 6 patients who had stent insertion for external compression are alive, and 2 of these patients had no complications related to stent insertion.

The 5 patients who died in the intensive care unit had multiple organ failure and sepsis at the time of stent deployment, and these conditions led to their death. One should therefore question the usefulness of endobronchial stents in such patients. Those patients who died later died of causes unrelated to stent deployment, eg, cerebrovascular accident, myocardial infarction.

In a series of 82 cases of large airway obstruction reported by Saad and colleagues [6], expandable metallic stents were inserted for airway complications related to lung transplantation in 11 patients or other benign conditions in 21 patients. Consistent with our experience, weaning from mechanical ventilation after stent placement was successful in the majority of cases. They concluded that airway stenting is an acceptable therapeutic alternative for patients with central airway obstruction who are not considered good surgical candidates and who are receiving mechanical ventilatory support. However, there was a high incidence of stent-related complications (53.7%), of which 15.9% was attributable to infection, 14.6% to granulation tissue formation, and 4.7% to stent migration during a mean follow-up period of 330 days.

Expandable metallic stents are associated with numerous potential problems once inserted. Furthermore, once deployed in the airway they are difficult, if not impossible, to remove. Therefore, their usefulness in the management of patients with benign large airway disease should be carefully questioned. In our opinion, these stents should not be an alternative to surgical intervention but rather should only be considered for those patients with medical comorbidities that contraindicate formal large airway surgery. Given the potential risks of airway perforation and stent fracture that may accompany manipulation of expandable metallic stents, together with the fact that once deployed, prospective bronchoscopic surveillance and possible further intervention may be required, we believe that these devices should only be used by clinicians skilled in their placement and removal.

We removed stents in 2 of our patients without complication. However, in 1 patient (patient 13), the airway was grossly abnormal at the time of stent removal but subsequently improved. Ideally, expandable metallic stents with a facility for easy removal could be considered as a temporary intervention for selected patients with benign disease and removed when the disorder has improved sufficiently or resolved.

In our series, 48% of parents experienced large airway complications. Given the fact that 13 patients died and that some deaths occurred early after stent insertion, it is possible that the figure would have been higher. Granulation tissue formation was the most common complication and occurred in 35% of our patients; the majority of patients with this complication required multiple ablations with Nd: YAG laser to effectively restore airway patency without damage to the stent. This tissue occurred most commonly around the uncovered ends of covered stents and through the metallic mesh of uncovered stents. Halitosis was common, and effective treatment for this was poor. It is appreciated that this complication can accompany other forms of tracheal or bronchial prostheses, but nevertheless it was distressing for our patients and caused social embarrassment. There were no cases of fistula formation complicating stent placement. Stent migration occurred in 1 patient within 2 months of placement for tracheal stenosis. The stent was removed, and a larger stent was inserted which did not migrate.

Expandable metallic stents are a useful strategy to manage selected patients with large airway obstruction secondary to benign disease. However, once deployed, they are very difficult to remove, and are associated with significant complications that require regular bronchoscopic surveillance and often further therapeutic intervention. We believe that these stents are best considered to be permanent adjuncts to restore airway patency when formal surgical intervention is not feasible. The decision to deploy these devices in patients with benign airway disorders should be made only after careful consideration by a multidisciplinary team, and should ideally be managed by clinicians who are skilled at their deployment and removal. In light of our experience, we believe that their deployment in septic patients with multiple organ failure should be questioned.

	References

Top Abstract Introduction Patients and Methods Results Comment References

 

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8. Madden BP, Park JE, Sheth A. Medium-term follow-up after deployment of Ultraflex expandable metallic stents to manage endobronchial pathology Ann Thorac Surg 2004;78:1898-1902.[Abstract/Free Full Text]
9. Madden BP, Sheth A, Ho TB, McAnulty GR, Sayer RE. A novel approach to the management of persistent postpneumonectomy bronchopleural fistula Ann Thorac Surg 2005;79:2128-2130.[Abstract/Free Full Text]
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