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Ann Thorac Surg 2002;73:938-944
© 2002 The Society of Thoracic Surgeons

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Original article: general thoracic

Experience with ultraflex expandable metallic stents in the management of endobronchial pathology

^a Department of Cardiothoracic Surgery, St. George’s Hospital, London, England, UK

Accepted for publication November 1, 2001.

* Address reprint requests to Dr Madden, Department of Cardiothoracic Surgery, St. George’s Hospital, Blackshaw Rd, London SW17 0QT, England UK

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
Background. Experience with Ultraflex expandable metallic stents (Micro-invasive, Boston Scientific, Watertown, MA) in the management of endobronchial pathologies leading to airway compromise is reported.

Methods. Between January 1999 and August 2000, twenty-eight expandable metallic stents were inserted into 25 patients (7 men and 18 women; median age, 65 years) who presented with respiratory distress. Each patient had comorbid medical conditions or end-stage malignancy that precluded formal surgical repair. Seventeen patients had intrinsic airway obstruction, 5 had extrinsic compression, 2 had a tracheal tear, and 1 had a tracheoesophageal fistula. Stents were inserted through a bronchoscope under direct vision. Eighteen patients received tracheal stents alone (1 of these patients received two tracheal stents), and 5 patients received bronchial stents only. Two patients received a tracheal and a bronchial stent. Twenty-one stents were covered and seven were uncovered.

Results. All patients had successful stents with restoration of airway patency and closure of tracheal defects. One patient developed a respiratory infection early after the operation. Follow-up bronchoscopy confirmed satisfactory stent position in each patient. Late complications included sputum retention, halitosis, and granulation tissue formation.

Conclusions. Ultraflex expandable metallic stents should be considered in the management of airway compromise in selected patients for whom formal surgical repair is inappropriate or contraindicated.

	Introduction

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Patients with respiratory distress as a consequence of large airway compromise require urgent investigation and treatment. Surgical intervention, although a mainstay of treatment, may not be appropriate for patients who have advanced malignancy and require palliation, or may not be possible for those patients with significant comorbid illness such as cardiorespiratory failure.

The deployment of tracheobronchial stents has proved effective at restoring airway patency in selected patients with extrinsic and intrinsic large airway obstruction and in closing defects. These stents can be also used as an adjuvant to other therapies such as laser ablation and tissue coagulation.

Ultraflex (Micro-invasive, Boston Scientific, Watertown, MA) self-expanding metallic stents have been designed to serve as an intraluminal stabilizing system. They provide excellent palliation for malignancy and are suitable also for treating granulation tissue formation, tracheomalacia, and stricture, and they can be deployed to seal tracheal defects. Covered or uncovered tracheal stents are available (Fig 1) and can be deployed under direct vision. The covered stents have the advantage of preventing proliferation of granulation or neoplastic tissue through them and can seal defects. Uncovered stents may reduce sputum retention and hence respiratory infection, but growth of tumor or granulation tissue through the stent can occur. During the course of our series, only uncovered bronchial stents were available to us for deployment.

View larger version (120K): [in this window] [in a new window]   Fig 1. Both covered and uncovered Ultraflex expandable metallic bronchial stents and a covered tracheal stent.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

The stents provide constant radial pressure maintaining patency while minimizing traumatic tissue compression, and they adapt to anatomic contours, thus enhancing patient comfort. The release mechanism allows controlled stent deployment. In comparison, most previous stents were placed by pushing them out of a sheath with an obturator, thus occasionally deploying them incorrectly.

All patients underwent rigid and flexible bronchoscopy under general anesthesia to confirm the endobronchial condition. The size of the stent was chosen so that it completely bridged the lesion and overlapped normal mucosa by at least 10 mm at each end. The expanded stent diameter was matched with the normal proximal lumen. The delivery system was than introduced through the rigid bronchoscope under direct vision. The stent was deployed by holding the handle hub in the palm and retracting the nylon suture. The crocheted knots were unraveled in a circular manner along the whole length of the stent. After the nylon suture had been completely removed, the delivery system catheter was taken out. Confirmation of satisfactory deployment of the stent was made by bronchoscopy during the procedure and by chest radiography. Check bronchoscopies were performed within 14 days of deployment and thereafter if there was a clinical indication, such as worsening symptoms, reduction in lung function, or deterioration in chest radiograph.

Between January 1999 and August 2000, we deployed 28 expandable metallic stents in 25 patients (7 men, 18 women; median age, 65 years) who presented with significant large airway compromise. The tracheal and bronchial pathologies were divided into three groups (Tables 1, 2, and 3).

Among the 5 patients presenting with extra-tracheal lesions, patient 18 presented with stridor from a non-Hodgkin’s lymphoma and mediastinal mass that was impinging on the trachea. A stent was deployed to secure the airway and to facilitate biopsy and introduction of chemotherapy. Patient 21 had a retrosternal goiter causing severe stridor. The initial clinical and bronchoscopic impression was underlying neoplasia eroding into the trachea and the patient presented as a medical emergency. This patient was medically unfit for a thyroid operation. Patient 22 had a previous operation for a right-sided aortic arch and had division of a tracheal band. Three years postoperatively this patient had progressive dyspnea develop, and flow volume loop studies confirmed tracheal compression. Rigid bronchoscopy confirmed extrinsic compression of the trachea. After consultation between the surgeon who performed the original operation and the patient, it was decided to deploy a stent. The last group consisted of 3 patients with a tracheal defect. Patient 23 had advanced inoperable esophageal carcinoma and presented with a tracheoesophageal fistula secondary to migration of an esophageal stent through the tracheal wall. Patients 24 and 25 developed tracheal wall perforation complicating percutaneous serial dilatational tracheostomy.

We believe that covered tracheal stents should be deployed for patients with proliferating tracheal tumors or granulation tissue or for patients with tracheal defects. At the time of study, covered bronchial stents were not available to us for clinical use. However the very fine mesh suggested to us that these stents could be successfully used for both inflammatory and noninflammatory bronchial pathologies and this was borne by our encouraging experience with the patients reported in this series. We acknowledge that uncovered tracheal stents could have been deployed to successfully manage conditions causing extrinsic tracheal compression (patients 18, 20, and 22) or tracheomalacia (patients 8, 9, and 10). Uncovered stents may reduce sputum retention and hence the risk of respiratory infection. Only 1 of these patients (patient 20) developed respiratory infection postdeployment of a covered stent. Patient 20 had cardiac failure and end-stage chronic obstructive pulmonary disease with a long-term history of recurrent bronchitis. It is not possible to assume that the patient’s respiratory infection poststent insertion occurred as a consequence of the covered stent, but in view of her background, insertion of an uncovered stent may have been preferable. Eighteen patients received tracheal stents alone (1 of these patients received two tracheal stents), and 5 patients received bronchial stents only. Two patients received a tracheal and a bronchial stent. Twenty-one stents were covered and seven were uncovered.

	Results

Top Abstract Introduction Material and methods Results Comment References

 
All patients were successfully stented with immediate restoration of airway patency or closure of defect proven by bronchoscopy with each patient. The stents were easy to insert, and general anesthesia was required for 15 to 20 minutes with each patient. Twenty patients reported symptomatic improvement, and the 3 patients with tracheomalacia were subsequently weaned from mechanical ventilatory support (Tables 4, 5, and 6). Having secured the airway it was then possible to use other treatment modalities (eg, radiotherapy) and to perform biopsies to confirm a histologic diagnosis without concern over further airway compromise. At follow-up bronchoscopy, the stent position was found to be satisfactory in each patient with no migration or airway dehiscence. Patient 17 had one episode of respiratory infection early postdeployment that was successfully treated with antibiotics. Late complications were sputum retention and recurrent chest infection in 4 patients (3 who had a covered tracheal stent deployed and 1 who had a bronchial stent deployed) that were successfully treated with nebulized hypertonic saline or N-acetyl cysteine to facilitate sputum expectoration, along with antibiotic treatment. Two patients (patient 10 and 20) developed halitosis poststent deployment. In 1 patient (patient 10) this was very problematic, restricting her social activities. There was no evidence of intercurrent infection or aspiration, and repeat bronchoscopy showed satisfactory stent position. Computed tomography scan of thorax and barium swallow were normal. Although we consulted with the stent manufacturer, we were unable to successfully treat this complication. One patient (patient 11) developed granulation tissue formation just beyond the distal end of the stent 1 month after deployment. The granulation tissue was treated with neodymium:yttrium-aluminum garnet laser ablation with no complication and no recurrence. We appreciate that treatment of granulations adjacent to the stent with neodymium:yttrium-aluminum garnet laser therapy could have theoretically damaged the stent. Although no damage to the stent occurred in our patient, we suggest that neodymium:yttrium-aluminum garnet laser therapy be used with caution in the management of this condition.

Up to the present time 15 patients are alive and 10 have died. Patients 8 and 9 died as a consequence of multiple organ failure postdeployment. Both patients required prolonged endotracheal intubation and mechanical ventilatory support predeployment and both had comorbid renal failure and chronic obstructive pulmonary disease. Patient 11 died 1 year after deployment from meningoencephalitis complicating an existing human immunodeficiency virus infection. Patient 17 died from cardiac failure 9 months after stent insertion. Patients 24 and 25 subsequently died from multiple organ failure unrelated to stent deployment.

	Comment

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Conditions that cause large airway defects or lead to a significant reduction in airway patency can be life threatening. Many patients are medically unfit for major surgical intervention or the overall prognosis is so poor that an alternative approach is needed to maintain airway patency or integrity and to palliate respiratory symptoms. Deployment of a stent provides a less invasive alternative in these patients.

The first commonly used tracheal stent was the Montgomery T tube, which was made of silicone and needed a tracheostomy for its use [1]. This stent often became blocked by dried secretions caused by lack of humidification. Subsequently silicone tubular stents [2–4] were used which did not require a tracheostomy. However, disadvantages of silicone include a tendency to interfere with normal mucociliary clearance and a tendency to block bronchial orifices, resulting in atelectasis and pneumonia; they can also be displaced. Wallace and colleagues [5] experimented with expandable metallic mesh tracheobronchial stents and found that they overcame these problems and commonly did not migrate or cause tracheitis. Further studies have validated the use of expandable metallic stents in a variety of endobronchial conditions [6–12]. These stents can be used as an adjunct to other therapies such as laser ablation and tissue coagulation and thus offer a potential alternative to surgical reconstruction of the trachea in selected patients [9]. However, unlike silicone stents, Ultraflex stents are difficult and dangerous to remove once inserted, and this can be a particular problem if the stent is penetrated by granulation tissue.

Tracheal resection and reconstruction are the gold standard for tracheal stenosis caused by benign granulation tissue formation [13, 14]. We have previously reported the usefulness of covered stents in the management of this complication [9]. There is concern in patients with a fibro-inflammatory etiology of their tracheal stenoses that continued inflammation renders the expandable uncovered metallic stent less effective. Indeed granulation tissue proliferation through the stent can be a difficult problem to address. The covered expandable stents are especially manufactured to prevent this complication from occurring. In the present series our patients were not medically fit for major reconstructive operations.

Management of malignant endobronchial conditions with covered stents has proved useful in improving the quality of life for end-stage patients who are not candidates for curative treatment [8]. Stents may relieve distressing respiratory symptoms and keep the airway patent during other forms of cancer therapy. One article describes the improvement of pulmonary physiology (FVC, FEV₁ and PEF) in patients with malignant airway lesions after stent deployment [15]. We were able to deploy stents in patients with tracheal and bronchial malignancies. For our patients with tracheal malignancy, covered stents were deployed with the intention of preventing malignant tissue proliferation through the mesh. This goal was achieved and the stents restored airway patency sufficiently for greater improvement of respiratory symptoms, and for some patients the stents maintained patency of the airway for adjuvant radiotherapy. Covered bronchial stents were unavailable to us at the time of deployment, but nevertheless the titanium mesh is very fine and prevented tumor growth through it.

Airway complications of anastomotic stricture and bronchomalacia after lung transplantation can be effectively managed with the use of self-expanding metallic stents [7, 10]. In our series, 3 patients who presented with anastomotic stricture after lung transplantation and 1 who had a fibrous stricture develop from previously treated pulmonary tuberculosis received bronchial stents with excellent functional results in terms of improvement in pulmonary function and clinical status. We did not encounter metallic strut fracture or breakage of nylon suture as reported with other forms of expandable stents [16].

Five patients in our series who presented with tracheal obstruction caused by extra-tracheal conditions were successfully stented. One of the patients had lymphoma, a recognized cause of acute airway obstruction [6]. In this patient stent deployment was essential to secure the airway, to obtain a tissue diagnosis (non-Hodgkin’s lymphoma) and to prevent further airway compromise during treatment. One patient presented with severe stridor that had a retro-sternal goiter compressing the trachea. A covered stent was inserted because the patient was medically unfit for a thyroid operation, the histologic diagnosis was unknown at the time of deployment, and the clinical and bronchoscopic presentation suggested that this patent had a malignant tumor eroding into the trachea. Two patients received a covered stent for tracheal compromise secondary to an esophageal carcinoma. One of these patients had extrinsic tracheal compression with infiltration into the trachea and the other patient had esophageal stent perforation and tumor erosion into the trachea that produced a tracheoesophageal fistula. In each patient a covered stent was inserted that successfully closed the fistula. Two patients presented with acute respiratory distress secondary to a tracheal tear complicating percutaneous serial dilatational tracheostomy. Covered stents sealed the defects with immediate relief of symptoms [17].

We appreciate that covered expandable metallic stents, as with silicone stents, have the potential disadvantage of impeding mucocillary clearance, thereby causing sputum retention. Three of our patients who received covered tracheal stents experienced this complication. We inserted the stents in these patients, while they were under general anesthesia, using rigid and fiberoptic bronchoscopy, because each patient had significant upper airway compromise and poor respiratory reserve. Therefore we were able to control the airway at all times during the procedure. We wanted to deploy the stents under direct vision using fiberoptic bronchoscopy to confirm stent position. The use of rigid bronchoscopy also allowed us to adjust the stent position easily, if necessary. Fluoroscopy was not used during stent insertion, and none of our patients needed balloon dilatation before stent deployment. The stents were easily inserted with excellent results and no complications of migration, airway dehiscence, or stent fracture.

Our encouraging experience with Ultraflex expandable metallic stents leads us to suggest that these stents should be considered for selected patients in the management of pathologies leading to airway compromise.

	References

Top Abstract Introduction Material and methods Results Comment References

 

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