Airway stents

Stent Evaluation for Expiratory Central Airway Collapse: Does the Type of Stent Really Matter?

BACKGROUND

Careful selection of patients with expiratory central airway collapse (ECAC) that may benefit from tracheobronchoplasty (TBP) can be aided by a short-term airway stent evaluation. This can be performed with either silicone Y-stents (SYSs) or uncovered self-expanding metallic airway-stents (USEMAS). No direct comparison has been made between these 2 stent types.

METHODS

This was a small retrospective review of consecutive patients that underwent a stent evaluation. A propensity score was used to match patients in the USEMAS and SYS groups. Outcomes included complications, changes in the health-related quality-of-life (HR-QoL), and changes in exercise capacity. Baseline measurements were compared with those obtained during stent evaluation and after TBP.

RESULTS

Forty-two patients with severe ECAC underwent USEMAS placement, while 18 patients had an SYS placed. Propensity score matching resulted in 13 matched SYS and USEMAS pairs. The SYS group had an increased rate of mucus plugging (38.5% vs. 0%, P <0.047). Although not statically significant, a clinical improvement was observed in HR-QoL and exercise capacity in the USEMAS group during stent placement. In patients who underwent TBP, both USEMAS and SYS groups had a statistically significant change in the Modified Medical Research Council Dyspnea Scale during stent evaluation and after TBP.

CONCLUSION

In patients with severe ECAC, short-term evaluation with airway stents appears to be safe and improves respiratory symptoms, HR-QoL, and exercise capacity. The use of USEMAS led to a lower complication rate, a greater improvement in HR-QoL and exercise capacity, and appeared to better predict how the patients would respond to TBP.

Indications and clinical outcomes of fully covered self-expandable metallic tracheobronchial stents in patients with malignant airway diseases

BACKGROUND

Airway stenting is an efficacious approach in management of malignant airway disease (MAD) with improvement in survival outcome.

OBJECTIVE

To determine the indications and long-term clinical outcomes of tracheobronchial stenting in patients with MAD.

METHODS

A cross-sectional review of 51 patients who underwent airway stenting from June 2011 to June 2019 was done. Paired t-test was used to compare mean difference of clinical characteristics between pre- and post-airway stenting. Kaplan-Meier curves were used to assess overall survival.

RESULTS

A total of 51 patients had stent insertion with mean age 46.63±17.10years including 27(52.9%) females. Mainly 37(72.5%) patients had esophageal and 06(11.8%) had lung cancer. The main indications were bronchial stenosis 18(35.3%), tracheal stenosis 11(21.6%) and Tracheo-esophageal/bronchial fistula 13(25.5%). Obstruction was intrinsic, extrinsic and mixed in 20(39.2%), 13(25.5%) and 5(9.8%) patients, respectively. There was statistically significant mean difference in pre- and post-procedure oxygen saturation (mean (M)=89.8, standard deviation (SD)=6.70 vs M =95.5,SD=2.54.p =0.001) and performance status (M =3.65,SD =0.6 vs M =2.59, SD=0.83.p =0.001). Overall median survival was 16±3.44 weeks, highest amongst patients with intrinsic obstruction (27±6.51 weeks).

CONCLUSION

Airway stenting is an effective endoscopic procedure to re-establish airway patency in MAD with minimal complications..

A combination therapy of photodynamic therapy (PDT) and airway stent placement using a transparent silicone stent

The aim of this study was to evaluate the feasibility of a combination therapy of photodynamic therapy (PDT) and airway stent placement using a transparent silicone stent (gold studded stent [GSS]). Laser irradiation (664 nm, continuous wave) was performed through the GSS using a straight and cylindrical fiber 1.0 cm away from a power meter. There are two types of GSS: the TD type for the trachea and the BD type for the bronchus. Laser outputs were set to 150 mW, 180 mW, 210 mW, 240 mW, 270 mW, and 300 mW. The laser powers passing through the both types of GSS were measured three times for each outputs and the averages were calculated. Based on the results, animal experiment was performed using two female pigs. Under general anesthesia, a GSS (BD type) was inserted into trachea of pigs, and PDT using NPe6 as a photosensitizer was performed by 100 J/cm² laser irradiation on parts of the trachea with and without a GSS. Immediately after and 1 week after PDT, pig tracheas were harvested and histological analysis was performed. Histological analysis of areas with or without the stent showed edematous changes between the cartilage and submucosal layer immediately after PDT, and necrotic changes 1 week later. The effectiveness of NPe6-PDT for pigs' trachea covered by the stent was same as trachea without the stent. The use of a GSS may enable PDT to be effective even in the area covered by the stent.

Airway stents

Stents and tubes to maintain the patency of the airways are commonly used for malignant obstruction and are occasionally employed in benign disease. Malignant airway obstruction usually results from direct involvement of bronchogenic carcinoma, or by extension of carcinomas occurring in the esophagus or the thyroid. External compression from lymph nodes or metastatic disease from other organs can also cause central airway obstruction. Most malignant airway lesions are surgically inoperable due to advanced disease stage and require multimodality palliation, including stent placement. As with any other medical device, stents have significantly evolved over the last 50 years and deserve an in-depth understanding of their true capabilities and complications. Not every silicone stent is created equal and the same holds for metallic stents. Herein, we present an overview of the topic as well as some of the more practical and controversial issues surrounding airway stents. We also try to dispel the myths surrounding stent removal and their supposed use only in central airways. At the end, we come to the long-held conclusion that stents should not be used as first line treatment of choice, but after ruling out the possibility of curative surgical resection or repair.

Placement of tracheobronchial silicone Y-stents: Multicenter experience and systematic review of the literature

Background:

Airway obstruction or tracheoesophageal fistula (TEF) near the tracheal carina requires placement of Y-shaped stents. Herein, we describe our multicenter experience with the placement of Dumon silicone Y-stents. We also conduct a systematic review for studies describing the deployment of airway silicone Y-stents.

Methods:

This was a retrospective analysis of consecutive subjects who underwent placement of silicone Y-stents. The clinical details including the underlying diagnosis, indication for the placement of silicone Y-stents, success of stent placement, and follow-up are presented. The PubMed and EMBASE databases were also reviewed for studies describing the placement of silicone Y-stents.

Results:

During the study, 27 silicone Y-stents were placed. The mean (standard deviation) age of the study population (85.2% males) was 57.7 (13.5) years. The stents were placed for airway obstruction in 77.8% and TEF in 29.6% of the patients. The most common underlying disease was carcinoma of the esophagus. The degree of airway obstruction was grade 3–4 in 18 subjects, and respiratory failure was encountered in 18 subjects. The stent was deployed successfully in all the subjects. No deaths were encountered during stent placement. Most subjects had rapid relief of symptoms following the procedure. Excessive secretions and mucostasis were the most common stent-related complications followed by the development of granulation tissue. The systematic review yielded nine studies (338 subjects with airway obstruction and/or TEF). The most common indication for silicone Y-stent placement was tracheobronchial obstruction and TEF due to malignancy. Benign disorders that necessitated stent placement included postintubation tracheal stenosis, airway malacia, and others. The stent was successfully placed in 98% with only one periprocedural death. Granulation tissue formation and mucostasis were the most common stent-related complications.

Conclusion:

Placement of silicone Y-stent is a safe and effective procedure that provides quick relief of symptoms in subjects presenting with airway obstruction and TEF at or near the tracheal carina.

Rigid bronchoscopy and mechanical debulking in the management of central airway tumors: an Indian experience

BACKGROUND

Treatment options for central airway tumors include surgery, radiotherapy, and in those with inoperable or emergent airway obstruction, therapeutic bronchoscopy. Herein, we report our experience with the exclusive use of rigid bronchoscope in the management of central airway tumors.

METHODS

Retrospective review of charts of patients who underwent rigid bronchoscopy and mechanical coring for the management of central airway (trachea and mainstem bronchi) tumors over a period of 2 years. "Successful" outcome was defined as procedure leading to reduction of luminal obstruction to <50% and improvement of respiratory distress. "Unsuccessful" outcome was defined in cases where the luminal obstruction could not be reduced by ≥50% or there was lack of improvement in the clinical status of the patient.

RESULTS

During the study period, 30 patients with symptomatic central airway tumors were encountered. Of these, 23 patients underwent 31 rigid bronchoscopic procedures. Respiratory failure was present in 15 (65.2%) patients. Adenoid cystic carcinoma was the most common primary tracheal tumor, whereas squamous cell carcinoma was the most common secondary tracheobronchial tumor. The procedure was successful in 19 (82.6%) patients. Complications were encountered in 10 of the 31 (32.3%) rigid bronchoscopies. There was no procedural mortality.

CONCLUSIONS

Rigid bronchoscopy and mechanical debulking as a sole therapy is an effective and safe procedure for airway obstruction resulting from tracheobronchial tumors.

Computed tomography measurements for airway stent insertion in malignant airway obstruction

BACKGROUND

Metallic airway stents for malignant airway obstruction are considered safe, yet are not without complications. This study reviews the role of computed tomography (CT) airway measurements for planning stent placement in malignant airway obstruction before the actual therapeutic procedure to avoid invasive diagnostic evaluation before the stent placement and to reduce complications.

METHODS

This study is a retrospective review of information from a stent order database and medical records of patients receiving stents for malignant airway obstruction at a university hospital over a 12-year period. CT scans were used to determine stent diameter by calculating mean diameters of healthy adjacent zones (proximal and distal), stent length (length of diseased airway), and location and number of potential stents. Results of CT planning before bronchoscopy were judged by complication rates.

RESULTS

Patient population consisted of 69 patients, 61.7±14.0 years old, 40 males, in whom 92 stents were inserted. The most frequent cause of airway obstructions was tracheobronchial cancer (32). All patients had nitinol stent placement; 66 stents were covered and 26 were uncovered. Follow-up time was 1 to 1067 days (median: 35 days). Complication rate was 10.1% and mainly involved the patients with tracheal obstruction (6). Complications included stent fractures (2), migration (2), granuloma (1), and infectious tracheitis (2). One early death within 24 hours after the procedure was not related to stent placement. Five patients required follow-up therapeutic bronchoscopy to treat the complications.

CONCLUSIONS

These results suggest that prestent planning by noninvasive method of obtaining CT scan provides optimal stent size and position, possibly avoiding a diagnostic bronchoscopy and reducing complications. Further prospective study is needed to confirm these results because of limitation of this study's design.

Multiplanar and two-dimensional imaging of central airway stenting with multidetector computed tomography

Background

Multidetector computed tomography (MDCT) provides guidance for primary screening of the central airways. The aim of our study was assessing the contribution of multidetector computed tomography- two dimensional reconstruction in the management of patients with tracheobronchial stenosis prior to the procedure and during a short follow up period of 3 months after the endobronchial treatment.

Methods

This is a retrospective study with data collected from an electronic database and from the medical records. Patients evaluated with MDCT and who had undergone a stenting procedure were included. A Philips RSGDT 07605 model MDCT was used, and slice thickness, 3 mm; overlap, 1.5 mm; matrix, 512x512; mass, 90 and kV, 120 were evaluated. The diameters of the airways 10 mm proximal and 10 mm distal to the obstruction were measured and the stent diameter (D) was determined from the average between D upper and D lower.

Results

Fifty-six patients, 14 (25%) women and 42 (75%) men, mean age 55.3 ± 13.2 years (range: 16-79 years), were assessed by MDCT and then treated with placement of an endobronchial stent. A computed tomography review was made with 6 detector Philips RSGDT 07605 multidetector computed tomography device. Endobronchial therapy was provided for the patients with endoluminal lesions. Stents were placed into the area of stenosis in patients with external compression after dilatation and debulking procedures had been carried out. In one patient the migration of a stent was detected during the follow up period by using MDCT.

Conclusions

MDCT helps to define stent size, length and type in patients who are suitable for endobronchial stinting. This is a non-invasive, reliable method that helps decisions about optimal stent size and position, thus reducing complications.

[Interventional bronchoscopy]

In the last decade, major advances have been made in interventional bronchoscopy. Notable techniques are tracheobronchial laser, endoprosthesis placement and endobronchial ultrasound bronchoscopy. The indications and applications for these three bronchoscopic techniques are reviewed. I.

Bronchial artery embolization before interventional bronchoscopy to avoid uncontrollable bleeding: a case report of endobronchial metastasis of renal cell carcinoma

Extreme caution should be taken to avoid uncontrollable bleeding in treating hypervascular tumors via bronchoscope. We report two cases of endobronchial metastasis of renal cell carcinoma treated with bronchial artery embolization (BAE) before endoscopic treatments. The intraluminal lesions were removed swiftly and safely. Although arterial embolization is not always efficacious in cases of tracheal lesions, BAE is effective for tumors located in the carina, bilateral main bronchus or intermediate bronchus. The addition of BAE before endoscopic tumor removal should be considered a treatment option in patients suffering from airway obstructions due to hypervascular tumors such as renal cell carcinoma.

Airway stents

Stents are used for palliation of symptoms of central airway obstruction caused by either malignant or benign conditions. Stents may be applied for maintaining airway patency after dilatation of postinflammatory and infectious strictures, for airway dehiscence after lung transplantation, and for the management of tracheobronchomalacia. Fistulas between trachea or bronchi and the esophagus and dehiscence of pneumonectomy stump can be protected with covered stents. Choice of stent depends on careful patient selection, characteristics of airway stenosis, physician's expertise, and availability of equipment. Placement of tube stents requires rigid bronchoscopy and dilatation of strictures beforehand, whereas metal stents can be applied using a flexible bronchoscope. Advantages and disadvantages of commonly used airway stents are discussed.

The role of airway stent placement in the management of tracheobronchial stenosis caused by inoperable advanced lung cancer

PURPOSE

To our knowledge there is no in-depth report on the benefits of airway stenting, which focuses specifically on patients with inoperable advanced lung cancer causing severe central airway obstruction. We evaluated the role of airway stenting as one aspect of the multidisciplinary management of advanced lung cancer.

METHODS

We performed airway stenting in 40 lung cancer patients, placing a total of 58 stents. Stenting was done as a final modality in 22 patients with terminal-stage lung cancer (group A). The other 18 patients received additional therapy after stenting (group B), 12 (66.7%) of whom were treatment-naïve on admission.

RESULTS

The performance status (PS) and Hugh-Jones classification (H-J) scores improved in both groups after stenting: from 3.56 to 2.48 (P = 0.001) and 4.29 to 3.20 (P = 0.004) in group A, and from 3.15 to 1.25 (P < 0.001) and 4.10 to 2.10 (P < 0.001) in group B, respectively. The median survival time and 1-year survival rate after stenting were 1.6 months and 5.1%, respectively, in group A, and 5.6 months and 25.0%, respectively, in group B.

CONCLUSIONS

Airway stenting followed by adjuvant therapy may improve the survival of treatment-naïve patients with severe symptomatic airway obstruction caused by advanced lung cancer.

Clinical application of the Natural Y stent in the management of benign carinal stenosis

BACKGROUND

The Y-shaped structure of the carinal bifurcation causes difficulties in the treatment of carinal stenosis. We describe a new Y-shaped silicone stent, called the Natural Y stent. We investigated its clinical efficacy through a review of patients with benign carinal stenosis who undewent consecutive Natural Y stent placement.

METHODS

Between January 2004 and February 2008, 11 patients underwent ballooning, neodymium:yttrium-aluminum-garnet laser resection, or bougienation (by rigid bronchoscopy) to dilate the airway, followed by placement of the Natural Y stent.

RESULTS

The underlying etiologies of carinal stenosis included posttuberculosis stricture in 7 patients (64%), postintubation stenosis in 2 (18%), and postoperative malacia in 2 (18%). All patients reported subjective symptomatic relief immediately after stent placement. No procedurally related deaths or immediate major complications occurred. Stent-related late complications included granulation tissue formation (64%) and mucostasis (18%, defined as > or = 50% narrowing). The median duration of overall stent placement was 439 days (range, 119 to 1729 days). The stents were successfully removed in 4 patients (36%) after a median of 409 days.

CONCLUSIONS

The Natural Y stent provides an effective and feasible therapeutic modality in patients with benign carinal stenosis, with or without previous thoracic airway interventions.

Endotracheal stenting therapy in dogs with tracheal collapse

Tracheal collapse in dogs is a common respiratory disorder, typically presenting with a history of chronic cough, increasing respiratory difficulties, and episodes of dyspnoea. Medical treatment is the therapy of choice and surgical repair is considered when patients do not respond well. Minimally invasive endotracheal stenting is a promising new therapy under investigation, but there remain significant challenges to overcome potential complications. The purpose of this article is to provide a comparative overview of intra-luminal stenting of the trachea in human and veterinary medicine. The currently available stents and their potential clinical application to the veterinary patient will be discussed.

[Multidetector CT evaluation of airway metallic stents]

INTRODUCTION

Stenting is accepted in managing patients with inoperable obstruction of the upper airways. The choice of the type as well as the dimensions of stents are crucial as it impacts on the success of the procedure and potential complications which must be diagnosed non-invasively.

STATE OF THE ART

The goal of this review is to present our multidisciplinary experience using multidetector CT as a minimally invasive technique for detecting airway obstructions, for evaluating preoperatively local anatomic conditions useful to determinate the type and size of metallic stents to be used, and following non-invasively the stent in order to detect various complications.

CONCLUSIONS

MDCT acquisition should use thin slices as multiplanar reformations and 3D reconstructions play an essential complementary role to axial images in pre- and post-stent placement settings.

Endobronchial stent placement for the management of airway complications after lung transplantation

PURPOSE

To retrospectively evaluate the efficacy and complications of endobronchial stent placement for the management of airway complications following lung transplant.

MATERIALS AND METHODS

From 1992 to 2003, tracheobronchial stenting was performed on 25 lung transplant recipients (16 male and 9 female; mean age 51.6 years; range 21-65 years). A total of 27 lesions were treated and 27 stents were deployed (nine bronchomalacia, 12 bronchial stenosis, three bronchial stenosis and bronchomalacia both and three anastomotic dehiscence). The clinical and bronchoscopic follow-up ranged from 1 month to 69 months.

RESULTS

The technical success was 100%. Eighty-four percent of patients had immediate relief in dyspnea. The overall complication rate following stent placement was 0.049 per patient per month (23 complications/471 patient months). Stent migration and granulation tissue formation were the most frequent complications. The mean percentage change in FEV-1 was significantly greater than zero at 1 month and 6 months (P<.05) post-stent placement. The mean percentage change in FEV-1 was marginally greater than zero at 12 months (P=.07).The mean percentage change in FVC was marginally greater than zero at 1 month and 6 months (P=.08) post-stent. It was not significantly greater than zero at 12 months (P=1.00).

CONCLUSION

Tracheobronchial stent placement provides effective palliation of postoperative airway complications in lung transplant with morbidity that can be managed effectively by available treatment options. Airway stenting may be used as a primary management option for airway complications after lung transplantation as a large number of patients are not suitable candidates for repeat surgery.

Comparison of natural and Dumon airway stents for the management of benign tracheobronchial stenoses

OBJECTIVE AND BACKGROUND

To investigate the utility and safety of the 'Natural stent', a newly designed silicone airway stent, the authors compared clinical outcomes and complications in patients who underwent silicone airway stenting for the management of benign airway stenosis.

METHODS

The medical records of 94 patients requiring the placement of 100 airway stents (43 Dumon and 57 Natural) were retrospectively reviewed in a tertiary referral hospital.

RESULTS

Post-tuberculous stenosis was the leading indication for airway stenting (74%), followed by post-intubation stenosis (21%). After intervention, dyspnoea improved in patients who underwent Dumon (90%) and Natural (86%) stenting. After stabilizing dyspnoea, stents could be successfully removed in half of the patients who underwent Dumon (54%) or Natural (49%) stenting. During a 42-month follow-up period, complication rates were similar in patients who underwent Dumon or Natural stenting.

CONCLUSION

Natural airway stent was as effective and safe as Dumon stent for the management of benign tracheobronchial stenoses.

Performance of a self-expanding silicone stent in palliation of benign airway conditions

INTRODUCTION

The Polyflex stent (Boston Scientific; Boston, MA) is a self-expanding, thin-walled, silicone stent. Its use has been described in the management of patients with malignant airway obstruction, yet reports of its use for treatment of benign airway conditions are rare.

STUDY

We report a retrospective review of our experience with the Polyflex stent in the management of benign airway conditions.

RESULTS

A total of 16 stents were deployed in 12 patients. The indications for the stent placement included the following: anastomotic stenosis following lung transplantation (LTR) [four patients]; tracheal stenosis (three patients); tracheobronchomalacia (two patients); tracheobronchopathiaosteochondroplastica (one patient); relapsing polychondritis (one patient); and bronchopleural fistula (one patient). Even though immediate palliation was established in most cases (90%), the incidence of complications was 75%. Stent migration was the most common consequence, with time to the event ranging from < 24 h to 7 months. One stent was expectorated within < 24 h. One patient coughed up a portion of the inner lining of the stent 7 months after its placement. Emergent bronchoscopy was required in four patients for mucous impaction. The complication rate was 100% in patients with LTR-related anastomotic stenosis.

CONCLUSION

The use of the Polyflex stent for the treatment of benign airway conditions is associated with a high complication rate. We have abandoned its use under such conditions in our practice.

The future of bronchoscopy in diagnosing, staging and treatment of lung cancer

Bronchoscopy is a central technique in diagnosing lung cancer, but also in different therapeutic approaches. A lot of techniques are available. The most common indication for bronchoscopy is for tissue sampling and determining the extent of lung cancer. Established diagnostic techniques are forceps biopsy, aspiration or brush cytology sampling, or needle aspiration. Laser therapy, electrocautery, cryotherapy and stenting are well-described techniques for the palliation of symptoms due to airway involvement in patients with advanced stages. Newer technologies, with an established role in clinical practice, are endobronchial ultrasound, autofluorescence bronchoscopy, and electromagnetic navigation. Other technologies, such as magnification, narrow-band imaging and confocal fluorescence microendoscopy, are in development for the use within the airways.

New tubular bioabsorbable knitted airway stent: feasibility assessment for delivery and deployment in a dog model

PURPOSE

The aim of this study was to determine whether it is possible to deliver and deploy a new device, a poly-L-lactic acid (PLLA) tubular knitted airway stent, under bronchoscopic guidance in a dog model.

DESCRIPTION

The delivery system consisted of a flexible balloon catheter (controlled radial expansion balloon dilator, M00558440, Boston Scientific Corporation, MA, USA) preloaded with a stent. A delivery catheter preloaded with a stent was advanced to a target point in the trachea under bronchoscopic guidance. Once the stent was positioned, the balloon was inflated for sixty seconds. The stent was in full contact with the tracheal wall upon deflation of the balloon.

EVALUATION

The stents were successfully delivered into the tracheal lumen and successfully deployed in all dogs.

CONCLUSIONS

This is the first study to prove the feasibility of delivering and deploying the PLLA stents in a dog model, using a balloon expansion technique. Further investigation with large numbers of subjects and long-term follow-up will be necessary to assess the utility of the bioabsorbable knitted tubular stent before clinical applications begin.

Short-term deployment of self-expanding metallic stents facilitates healing of bronchial dehiscence

Bronchial dehiscence after lung transplantation is difficult to treat and associated with high mortality. We describe our experience using self-expanding metallic stents to treat post-lung transplant bronchial dehiscence. From January 1995 to June 2004, 189 single and 118 double lung transplants were performed in our institution, totaling 425 at-risk bronchial anastomoses. Seven (1.6%) incidents of life-threatening bronchial dehiscence were treated with self-expanding metallic stents. The interval between transplant and diagnosis of dehiscence was 29.1 +/- 18.5 days. All patients presented with respiratory distress, and three required mechanical ventilation. Self-expanding metallic stent placement resulted in complete bronchial healing. All three patients with respiratory failure requiring mechanical ventilation were successfully weaned after stent placement. In two later cases, the stents were electively removed after adequate healing of the dehiscence. Complications included stent migration (one patient) and in-stent stenosis (three patients). Two of these patients required repeat stent insertion after removal, due to bronchomalacia. In patients with life-threatening bronchial dehiscence, self-expanding metallic stents offer prospects for a successful outcome. Self-expanding metallic stents are known to be associated with significant granulation tissue formation, and this property provides a platform for healing of dehiscence and, in time, peribronchial soft tissue grows in to cover the defect, allowing stent removal.

Endoscopic Removal of Metallic Airway Stents

BACKGROUND

Complications of metallic airway stents include granulation tissue formation, fracture of struts, migration, and mucous plugging. When these complications result in airway injury or obstruction, it may become necessary to remove the stent. There have been few reports detailing techniques and complications associated with endoscopic removal of metallic airway stents. We report our experience with endoscopic removal of 30 such stents over a 3-year period.

METHODS

We conducted a retrospective review of 25 patients who underwent endoscopic stent removal from March 2001 to April 2004. The patients ranged in age from 17 to 80 years (mean, 56.3 years). There were 10 male and 15 female patients. The stents had been placed for nonmalignant disease in 20 patients (80%) and malignant disease in 5 patients (20%). All procedures were done under general anesthesia with a rigid bronchoscope. Special attention was focused on the technique of stent removal and postoperative complications.

RESULTS

Thirty metallic airway stents were successfully removed from 25 consecutive patients over a 3-year period. The basic method of removal involved the steady application of traction to the stent with alligator forceps. In all cases, an instrument such as the barrel of the rigid bronchoscope or a Jackson dilator was employed to help separate the stent from the airway wall before removal was attempted. In some instances, the airway wall was pretreated with thermal energy prior to stent removal. Complications were as follows: retained stent pieces (n = 7), mucosal tear with bleeding (n = 4), re-obstruction requiring temporary silicone stent placement (n = 14), need for postoperative mechanical ventilation (n = 6), and tension pneumothorax (n = 1).

CONCLUSIONS

Although metallic stents may be safely removed endoscopically, complications are common and must be anticipated. Other investigators have described airway obstruction and death as a result of attempted stent removal. Placement and removal of metallic airway stents should only be performed at centers that are prepared to deal with the potentially life-threatening complications.

Multislice CT Evaluation of Airway Stents

Tracheobronchial stents are playing an increasing role in the palliative treatment of large airway obstruction due to a variety of conditions, including extrinsic compression, intraluminal disease, and malacia. Computed tomography (CT) plays an important role in aiding planning of stent placement and in detecting various stent complications. In this pictorial essay, we illustrate and review the role of multislice CT in the pre- and post-stent placement settings. A special emphasis is placed upon the characteristic CT appearance of specific stent complications and upon the role of CT multiplanar reformations and 3-dimensional (3-d) reconstruction techniques.

Development of an automated electroplater and dosimetry system for the electrodeposition and quality control of radioactive stents

An automated electrodeposition system for the preparation of radioactive stents and an automated dosimetry system based on the Optidos beta-scintillation detector for the quality control of the radioactive stents have been developed. Custom-made application software programmed in Visual Basic was used to control liquid flow and electroplating currents in the electrodeposition system, and to run the dual motion actuator and radiation detector for the automated measurement of the radioactivity distribution. The automation of the electroplating process increased the precision, ease, repeatability, and radiation safety of the process. The radioactive beta-emitting 188Re stents might be useful for the treatment of patients with inoperable lung cancer.

Preparation and characterization of radioactive Co/188Re stents intended for lung cancer treatment using an electrodeposition method

A procedure for electroplating a Co/(188)Re alloy layer on metal coils (stents) at room temperature was developed. The electroplating of the Co/(188)Re alloy layer was carried out at a current density of 93 A m(-2) and produced a physically strong Co/(188)Re alloy layer that adhered well to a thin gold strike layer on top of the stent material. The final gold layer was also stable. An empirically-found equation correlates the radioactive electroplating efficiency factor to the concentration of the radioisotope and was used to deposit predetermined amounts of radioactivity on the stent surface. Radioactive stents can be prepared and quality control performed within 2 hours using an automated electroplater and dosimetric quality control system. The radioactivity was homogeneously distributed on the stent surface. The in vitro stability in human plasma at 37 degrees C was found to be greater than 95% for both Wallstent and Ultraflex stent after 72 hours of incubation. A clinical pilot trial is planned after successful completion of animal testing.

Central Airway Obstruction

Central airway obstruction is a problem facing all medical and surgical subspecialists caring for patients with chest diseases. The incidence of this disorder appears to be rising because of the epidemic of lung cancer; however, benign causes of central airway obstruction are being seen more frequently as well. The morbidity is significant and if left untreated, death from suffocation is a frequent outcome. Management of these patients is difficult, but therapeutic and diagnostic tools are now available that are beneficial to most patients and almost all airway obstruction can be relieved expeditiously. This review examines current approaches in the workup and treatment of patients suffering from airway impairment. Although large, randomized, comparative studies are not available, data show significant improvement in patient outcomes and quality of life with treatment of central airway obstruction. Clearly, more studies assessing the relative utility of specific airway interventions and their impact on morbidity and mortality are needed. Currently, the most comprehensive approach can be offered at centers with expertise in the management of complex airway disorders and availability of all endoscopic and surgical options.

Progressive experience in tracheal stenting with self-expandable stents

We experienced an unacceptably high 21% complication rate with the stainless steel Gianturco stent: a 68-month mean follow-up (range: 37-96 months) of 23 patients revealed three stent fractures and two migrations. Consequently, we began using nitinol mesh stents (Ultraflex) for fibrous stenoses and silicone-covered prostheses (Rush) for proliferative tracheal tumors. The extractable nitinol stent, made from alloy with thermal memory, was palliatively used in 15 patients with fibrous tracheal stenosis; the mean follow-up currently covers 21 months (range: 1-60 months). The silicone-covered prosthesis was used for two patients with inoperable tracheal tumor; follow-up covers 4 months and 2 months, respectively. The prostheses were positioned under visual guidance via the endoscopic approach. The median forced inspiratory volume in 1 s (FIV1) improved from 2.1 l/s (IQR: 0.7-2.4) to 3.2 l/s (IQR: 0.9-3.4) (P=0.018, Wilcoxon signed rank test). The median ratio of peak inspiratory flow (PIF 50%) to peak expiratory flow (PEF 50%) was 1.0 preoperatively (IQR: 0.8-1.5) and 1.8 postoperatively (IQR: 0.6-6.3). Between months 1 and 12, six granulomas developed. Five were treated with antibiotics and steroid aerosol inhalation therapy and one required CO2 laser vaporization. On day 10, one stent migration was observed. The migrated stent was substituted. To date, no stent fracture has been observed. Nitinol and silicone-covered prostheses can be proposed for the palliative treatment of fibrous tracheal stenoses and tracheal tumors, respectively.

The role of self-expandable metallic stents for the treatment of airway complications after lung transplantation

BACKGROUND

Airway complications continue to be an important source of morbidity and mortality after lung transplantation (LTx). Different approaches have been used for their nonsurgical management. We describe our experience using self-expandable metallic stents (SEMSs) in patients with airway complications post-LTx.

METHODS

We present a retrospective analysis of stent related-data of all the LTx patients who received SEMSs to treat postoperative airway complications.

RESULTS

Between January 1992 and December 2001, 36 of 253 patients (14.2%) developed post-LTx airway complications involving 40 of 348 anastomoses (11.5%). A total of 15 SEMSs were placed in 12 patients (mean age 47.3+/-9.6 years) for tracheobronchomalacia, stenosis, and anastomotic dehiscence, including one patient referred from an outside hospital. Mean follow-up was 20.1+/-19.5 months (range 1.2-58 months). Patency and symptom improvement were achieved in 11 of 12 patients. Stenting of the airway led to successful weaning of two patients who were on prolonged mechanical ventilation. Suture dehiscence was effectively managed in two patients who were not candidates for surgical repair. Overall, the complication rate was 0.040 complications per patient per month (total number of complications and total number of months using the stent). Bacterial bronchitis (four patients) and obstructive granulomas (three patients) were the most frequent complications. The survival of LTx patients with airway SEMSs was similar when compared with the survival of all other LTx patients (P=0.74).

CONCLUSIONS

SEMSs are safe and effective in the management of airway complications in selected patients post-LTx. Weaning from mechanical ventilation and management of anastomotic dehiscence are the unique attributes of this device.

Follow-up after stent insertion in the tracheobronchial tree: role of helical computed tomography in comparison with fiberoptic bronchoscopy

The aim of this study was to compare helical CT with fiberoptic bronchoscopy findings to appraise the medium-term results of proximal-airways stenting. Twenty-five patients with 28 endobronchial metallic stents inserted for local advanced malignancy ( n=13) or benign diseases ( n=12) underwent follow-up CT from 3 days to 50 months (mean 8 months). All studies were obtained using helical CT with subsequent multiplanar reformation and three-dimensional reconstruction including virtual bronchoscopy. The location, shape, and patency of stents and adjacent airway were assessed. The results of CT were compared with the results of fiberoptic bronchoscopy obtained with a mean delay of 2.5 days (SD 9 days) after CT scan. Twelve stents (43%) remained in their original position, patent and without deformity. Sixteen stents were associated with local complications: migration ( n=6); external compression with persistent stenosis ( n=4); local recurrence of malignancy ( n=4); fracture ( n=1); and non-congruence between the airway and the stent ( n=1). The CT demonstrated all the significant abnormalities demonstrated at fiberoptic bronchoscopy except two moderate stenoses (20%) related to granulomata at the origin of the stent. Ten of 14 stents inserted for benign conditions were without complications as compared with 2 of 14 in malignant conditions ( p=0.008). Computed tomography is an accurate noninvasive method for evaluating endobronchial stents. The CT is a useful technique for follow-up of patients who have undergone endobronchial stenting.

Complications of Tracheobronchial Airway Stents

OBJECTIVE: Our goal was to identify and analyze airway stent complications and to devise approaches to manage stent complications.

STUDY DESIGN AND SETTING: We conducted a retrospective review of patients from a tertiary medical center.

METHODS: Twenty-eight airway stents were placed in 23 patients for benign (n = 15) and malignant (n = 13) tracheobronchial diseases. All patients were followed clinically for signs of complications.

RESULTS: Nine complications (8 in those with benign disease and 1 in a patient with malignant disease) were identified and included stent migration (n = 3), excessive granulation tissue (n = 2), stent fracture (n = 1), poor patient tolerance (n = 2), and inability to place (n = 1). Avoidance and management strategies for stent complications are introduced.

CONCLUSION: Tracheobronchial stents provide minimally invasive therapy for significant airway obstruction. Stent complications are more frequently encountered in the long-term treatment of benign conditions. Stents can be successfully removed endoscopically if complications arise, but the longer a metallic stent is in place, the more difficult it is to remove.

SIGNIFICANCE: As airway stent use increases, proper management will be required to avoid and manage complications. This is the first report to focus on stent complications and their management.

Ultraflex stents for the management of airway complications in lung transplant recipients

OBJECTIVE

We present our experience with the use of the Ultraflex (nitinol) stents in the management of airway complications in lung transplant (LT) recipients.

METHODOLOGY

Nine LT recipients underwent insertion of uncovered Ultraflex stents. Mean change in FEV1, duration to formation of granulation tissue and follow-up post-stent insertion were compared with results obtained in LT recipients who had undergone Gianturco stent (n = 10) and Wallstent insertion (n = 16).

RESULTS

Mean improvement in FEV1 after insertion of Gianturco, Wallstent and Ultraflex stents was 670 +/- 591 mL, 613 +/- 221 mL and 522 +/- 391 mL, respectively. No patient with an Ultraflex stent developed mucus plugging or stenosis at stent extremity at a follow up of 263 +/- 278 days. The mean and median duration to stenosis at stent extremity for patients with Gianturco stents was 102 +/- 85 days and 73 days, respectively, compared with 132 +/- 87 days and 142 days, respectively, for patients with Wallstents. Stricture formation in the middle of the Ultraflex stent occurred bilaterally, at the level of anastomosis in one patient in whom stent placement was undertaken in the presence of inflammation. Stent migration in one patient was related to undersizing of the stent diameter relative to the airway diameter. A larger diameter relative stent was subsequently inserted successfully.

CONCLUSION

Ultraflex stents appear to have fewer long-term complications when used in the management of airway complications following LT.

The use of selective bronchography in predicting reversal of neoplastic obstructive atelectasis

OBJECTIVES

To assess the ability of selective bronchography to predict which patients with neoplastic postobstructive atelectasis will respond to interventional therapies directed at the reexpansion of the affected lung. Furthermore, to compare the utility of selective bronchography with the current predictive standard that reversal of postobstructive atelectasis is unlikely when it is > or = 4 weeks in duration (ie, the 4-week rule).

DESIGN

A prospective observational study.

SETTING

A tertiary care referral center/medical school.

PATIENTS

Twenty-seven consecutive patients with advanced lung cancer or other malignancy, with documented neoplastic postobstructive atelectasis involving a total of 44 lobes.

INTERVENTIONS

Lobar collapse was documented radiographically. The duration of atelectasis was investigated and quantified as accurately as possible. Prior to the use of interventional therapies, selective bronchography was performed on each collapsed lobe, and the results were documented. Bronchography results did not influence the decision to proceed with interventional therapies. Patients had each of their collapsed lobes manipulated by interventional techniques that were directed at reexpansion of the lung. One week after the patient underwent the intervention, the degree of reexpansion was assessed radiographically.

RESULTS

Interventional therapies leading to significant reversal of airway narrowing were completed in all 44 lobes. These were successful in reexpanding 28 of 44 collapsed lobes (64%). Selective bronchography demonstrated the following two distinct patterns: an intact bronchial tree (ie, tree pattern); or the absence of a distinguishable, distal bronchial tree (ie, blush pattern). The sensitivity of selective bronchography to predict reexpansion is 1.00 (95% confidence interval [CI], 0.90 to 1.00), and its specificity is 0.56 (95% CI, 0.30 to 0.80). There were no complications attributable to selective bronchography. The sensitivity of the 4-week rule to predict reexpansion is 0.61 (95% CI, 0.41 to 0.78), and its specificity is 0.75 (95% CI, 0.48 to 0.93). The results of selective bronchography and use of the 4-week rule were significantly different in predicting which lobes would reexpand and which would not (p = 0.0026). Using selective bronchography to predict the reversal of lobar atelectasis, the positive predictive value of the tree pattern was 0.80 and the negative predictive value of the blush pattern was 1.00. The values for the 4-week rule are 0.81 and 0.52, respectively.

CONCLUSIONS

Selective bronchography is a useful tool for predicting whether patients with neoplastic postobstructive atelectasis would benefit from interventional techniques that are directed at lobar reexpansion. Selective bronchography appears to be superior to the 4-week rule in this regard.

Endoscopically placed expandable metal tracheal stents for the management of complicated tracheal stenosis

BACKGROUND

Metal stents have been advocated to manage complicated tracheal stenosis.

OBJECTIVE

The purpose of this investigation is to review the effectiveness of endoscopic placement of tracheal expandable metal stents for complicated tracheal stenosis.

METHODS

The charts of 6 patients who have undergone placement of metal expandable stents between 1998 and 2000 were reviewed.

RESULTS

Initially, all patients enjoyed immediate palliation of symptomatic tracheal stenosis. Eventually, 4 patients developed significant granulation tissue and/or recurrent stenosis, requiring intervention within 6 months after placement of the stent. One patient required the removal of the stent and placement of a T-tube silicone stent.

CONCLUSIONS

Metal stents provide temporary palliation for tracheal stenosis. Metal stents, however, are associated with a high incidence of obstruction with granulation tissue. Their use should be limited to a select group of patients with a short life expectancy (because of other comorbidities) or patients who are not good candidates for reconstructive surgery and/or who refuse or cannot tolerate a tracheotomy.

Therapeutic bronchoscopy in lung cancer. Laser therapy, electrocautery, brachytherapy, stents, and photodynamic therapy

Therapeutic bronchoscopic techniques such as LPR, EC, brachytherapy, stents, and PDT are effective tools in the palliation and local control of lung cancer. Palliation of malignant tracheobronchial obstruction by LPR, stents, brachytherapy, PDT, or a combination thereof results in relief of dyspnea, hemoptysis, and postobstructive pneumonia. Importantly, it avoids intubation in patients with respiratory distress and facilitates the weaning of patients from MV. In the exciting field of lung cancer screening and treatment of early lung cancer, PDT, brachytherapy, EC, and LPR may represent treatment alternatives to surgical resection, especially in a select group of patients with high surgical risk or favorable endobronchial lesions. Clinicians await the results of future studies, which will (1) better define the impact of each treatment modality on patient care in terms of cost, survival, and improvement in quality of life, and (2) determine the optimal combination therapy relative to bronchoscopic and conventional treatment for effective palliation and cure of lung cancer.

New tubular bioabsorbable knitted airway stent: biocompatibility and mechanical strength

OBJECTIVE

This study examines the biocompatibility and suitability of a new tubular bioabsorbable knitted stent made of poly-L -lactic acid in normal rabbit airways and examines the mechanical strength of this stent in vitro.

METHODS

A tubular knitted airway stent (group B, n = 15) made of poly-L -lactic acid wire was implanted operatively in New Zealand White rabbits intratracheally; silicone stents served as controls (group A, n = 8). The cervical trachea was exposed, and the stent was implanted. Up to 40 weeks after stent implantation, the rabbits were killed, at which time bronchoscopy, histologic examination, and scanning electron microscopic study was done. We tested poly-L -lactic acid stents and silicone stents for their mechanical strength in vitro. We subjected stents to area loads and measured their mechanical strengths.

RESULTS

In group A, which received silicone stents, 3 (37.5%) rabbits died within 4 weeks of stent implantation as a result of airway obstruction by secretions inside the stent lumen. In group B, poly-L -lactic acid stents, 1 (6.7%) rabbit died 3 weeks after implantation because of weakness caused by anorexia. In the remaining animals, except for 1 animal with stent trouble, the bronchial lumen was fully open until the 40th week after implantation. After 40 weeks of follow-up, the stents disappeared, except for nonabsorbable suture in the bronchial wall. None of the animals in group B died of airway complication. Histologic examination and scanning electron microscopic examination of the group A silicone stents showed marked regression of ciliated cells under the stent. In group B the ciliated epithelium was preserved, and there were numerous capillary blood vessels in the submucosa. In scanning electron microscopy of the group B poly-L -lactic acid stents, the ciliated cells were preserved between the mesh holes of the stent. For diameters between 4 and 6 mm, the mechanical strength of silicone stents was greater than that of poly-L -lactic acid stents. However, the mechanical strength of poly-L -lactic acid stents increased as a function of their diameter.

CONCLUSION

A new tubular bioabsorbable stent made of poly-L -lactic acid is biocompatible in normal rabbit airways, indicating that poly-L -lactic acid is a promising material for airway stents for clinical use.

Multi-detector row CT of thoracic disease with emphasis on 3D volume rendering and CT angiography

Multi-detector row computed tomography (CT) with three-dimensional (3D) volume rendering provides a unique perspective on thoracic anatomy and disease. Multi-detector row CT allows shorter acquisition times, greater coverage, and superior image resolution. Three-dimensional volume rendering now permits real-time, interactive modification of relative pixel attenuation in an infinite number of planes and projections. In vascular imaging, this technique provides image quality that equals or surpasses that of conventional angiography. Its use has expanded to aid in diagnosis and surgical planning, often obviating conventional or digital angiography and reducing costs. It is reliable in depicting clot and the pulmonary vasculature and may also be used to evaluate thoracic venous anomalies (eg, pulmonary arteriovenous malformations) and to plan therapy. Airway imaging with multi-detector row CT with 3D volume rendering is particularly useful in the planning and follow-up of stent placement. In diffuse lung disease, this technique can increase nodule detection and help differentiate between small nodules and vessels. It is also helpful in imaging the musculoskeletal system and the thoracic cage. Multi-detector row CT with 3D volume rendering has enhanced the conventional roles of thoracic CT and challenged the supremacy of other imaging modalities. It will likely play a leading role in future radiologic research and practice.