Metallic Stents for Tracheobronchial Pathology Treatment

State of the Science in Tracheal Stents: A Scoping Review

OBJECTIVE

Recent material science advancements are driving tracheal stent innovation. We sought to assess the state of the science regarding materials and preclinical/clinical outcomes for tracheal stents in adults with benign tracheal disease.

METHODS

A comprehensive literature search in April 2021 identified 556 articles related to tracheal stents. One-hundred and twenty-eight full-text articles were reviewed and 58 were included in the final analysis. Datapoints examined were stent materials, clinical applications and outcomes, and preclinical findings, including emerging technologies.

RESULTS

In the 58 included studies, stent materials were metals (n = 28), polymers (n = 19), coated stents (n = 19), and drug-eluting (n = 5). Metals included nitinol, steel, magnesium alloys, and elgiloy. Studies utilized 10 different polymers, the most popular included polydioxanone, poly-l-lactic acid, poly(d,l-lactide-co-glycolide), and polycaprolactone. Coated stents employed a metal or polymer framework and were coated with polyurethane, silicone, polytetrafluoroethylene, or polyester, with some polymer coatings designed specifically for drug elution. Drug-eluting stents utilized mitomycin C, arsenic trioxide, paclitaxel, rapamycin, and doxycycline. Of the 58 studies, 18 were human and 40 were animal studies (leporine = 21, canine = 9, swine = 4, rat = 3, ovine/feline/murine = 1). Noted complications included granulation tissue and/or stenosis, stent migration, death, infection, and fragmentation.

CONCLUSION

An increasing diversity of materials and coatings are employed for tracheal stents, growing more pronounced over the past decade. Though most studies are still preclinical, awareness of tracheal stent developments is important in contextualizing novel stent concepts and clinical trials. Laryngoscope, 2021.

Clinical Outcomes of Complications Following Self-Expandable Metallic Stent Insertion for Benign Tracheobronchial Stenosis

Background and Objectives: The use of metallic stents in benign TBS is controversial. Here, we report the clinical outcomes of patients who developed complications due to self-expandable metallic stent (SEMS) insertion for benign TBS. Materials and Methods: Our institution, which is the largest and most active referral hospital for airway stenosis in South Korea, only uses silicone stents. We conducted a retrospective review of 20 patients referred after the insertion of SEMS for benign TBS from 2006 to 2015. Results: All 20 patients underwent rigid bronchoscopy for SEMS removal due to airway obstruction from granulation tissue overgrowth. All but one (95%) experienced successful removal of the SEMS. During a median follow-up period of 40 months, a median of seven rigid bronchoscopies per patient was needed to maintain airway patency. Three (15%) patients suffered acute complications during SEMS removal (bleeding (10%) and fistula (5%)). All patients suffered chronic complications (granulation tissue (80%), stent migration (58%), mucostasis (55%), and restenosis (43%)). Eventually, 15 patients (75%) needed airway prostheses (silicone stent (75%) and tracheostomy (25%)). Conclusion: Our findings indicate that SEMS should be avoided until positive results are consistently reported by high-quality studies in patients with benign TBS.

A new airway spiral stent designed to maintain airway architecture with an atraumatic removal after full epithelization-Research of feasibility and viability in canine patients with tracheomalacia

OBJECTIVE

Surgical management of tracheomalacia is a challenge, with current treatments still presenting numerous complications. In the field of veterinary medicine, this same pathology is present in a significant number of dogs. For this reason, we present an experimental clinical trial performed on canines with tracheobronchomalacia, using a new atraumatic removable tracheal spiral stent (SS). Both implantation procedure and clinical improvement have been analyzed in this study.

METHODS

In this study, four small dogs, a mean weight of 4.89 kg and body condition scores IV-V, were included. SS was implanted by two different surgical approaches. Image and clinical follow-up have been performed during 90 days. Symptoms were evaluated from 1 to 10 every week.

RESULTS

This study achieved 100% technical and clinical success. Median tracheal diameters were as follows: cervical 10.85 (3.3), inlet 7.75 (2.1), and carina 7.75 (1.9) mm, and length was 77.5 (26) mm. A 12 × 10 × 100-mm SS was implanted in all cases. Goose honk cough punctuation improved from 8 to 1; also, there were important changes in exercise intolerance, a mean weight loss of 8.76%. The values of modified Karnofsky scale varied from 50 (20) before surgery to 90 (10) after 30 days of surgery. Neither granuloma tissue nor fractures of the prosthesis was observed.

CONCLUSION

The results in dogs are promising, and a new therapeutic alternative seems to be available for veterinarian field. The similarity of this disease between dogs and newborns suggests that this SS design can also be useful for human trials.

Reactivity Study of a Biodegradable Polydioxanone Tracheal Stent in a Rabbit Model

INTRODUCTION

The objective of this study was to evaluate tracheal reactivity induced by a biodegradable polydioxanone tracheal stent.

MATERIALS AND METHODS

Twenty-two rabbits were divided into 3 groups assigned to different survival times (30, 60 and 90days post-implantation). A biodegradable stent was implanted in each animal, except for 1 of each group (negative control). Implantation was performed through a small tracheotomy under fluoroscopic control. CT and histopathological studies were scheduled at the end of survival times.

RESULTS

No animal died during the procedure or follow-up. The stent had disappeared in 100% of the cases at 90days, in 50% at 60days, and in none at 30days. CT studies revealed a greater tracheal wall thickness at 30days than at 60 and 90days (1.60±0.41mm in the central part of the stent versus 1.11±0.18 and 0.94±0.11; P=.007, respectively). No granulomas were observed on histopathology. Some degree of histological changes were noted at 30days, which had reduced at 60 and 90days. Differences were also found in both CT and histology between animals in which the stent was present and animals in which it had degraded.

CONCLUSIONS

Polydioxanone stents produce a mild reaction that reverts with tracheal degradation. The use of these biodegradable stents in benign tracheal disease is promising.

Clinical outcomes of self-expandable metallic stents for malignant obstructive atelectasis

Self-expandable metallic stents (SEMSs) have been widely used in the treatment of malignant central airway obstruction. However, few reports focus on the treatment of atelectasis and how to estimate the prior probability of success via SEMSs placement, This current study aimed to study the safety and effectiveness of SEMSs for the treatment of obstructive atelectasis, and the value of preoperative CT enhancement for ventilation of atelectasis via SEMSs placement. A total of 35 patients with obstructive atelectasis (29 male and 6 female) was included from February 2012 to March 2018. The procedures were performed under fluoroscopic guidance, and bronchoscopic laser resection was performed for severe restenosis cases after SEMSs placement. Clinical and functional pulmonary data were recorded before and 3 months after the procedure. Follow-up involved clinical data and radiographic techniques at 48 h and at 1-, 3-, 6-, and 12-month intervals. Thirty-eight SEMSs were successfully implanted in 34 patients, included 29 Y type tracheal stents, 4 small y stents, and 5 straight airway stents. After stenting, 26 cases showed full ventilation, and 3 cases were partially ventilated. The technical success and clinical success was 97.1% and 82.9%, respectively. A higher maximum enhancement CT value was found in patients with full ventilation. Mean follow-up time was 18.8 ± 4.0 months. Eight cases showed restenosis and received endoscopic laser resection, included 1 case underwent removal and 3 cases received second stenting. There were 2 cases of perioperative non-operative death, and 11 cases of post-discharge death (2 cardiac deaths and 9 malignant tumors). The survival rates of 3 months, 1 year and 2 years were 78.6%, 58.5% and 58.5%, respectively. In conclusion, SEMSs placement is safe and effective for obstructive atelectasis, and the preoperative CT enhancement played an important role in estimating the prior probability of success in the treatment of atelectasis via SEMSs placement.

Incidence, Etiology, and Clinicopathologic Features of Endobronchial Benign Lesions: A 10-Year Consecutive Retrospective Study

BACKGROUND

Airways can be affected by non-neoplastic lesions leading to critical stenosis of the lumen. Incidence, etiology, and clinical significance of endobronchial benign lesions are not systematically characterized.This study aimed to assess the epidemiology of nonmalignant processes involving the bronchial tree on clinical, pathologic, endoscopic, and radiologic grounds.

METHODS

We retrospectively analyzed bronchoscopy procedures over 10 years at the Bronchoscopy Unit of Modena University Hospital. All the endoscopically growing benign lesions with histologic confirmation were considered. For each lesion, we evaluated demographics, clinical features and outcome, the endoscopic aspect and radiologic characteristics by means of computed tomography as assessed by 2 experienced radiologists blinded with regard to the diagnosis.

RESULTS

Over the study period, we analyzed 10,431 bronchoscopies and identified 2075 cases of tracheobronchial alterations. Among these, 11.2% had a benign etiology with an average annual incidence of 23 new cases/year and a general incidence of 2.2%. Anthrachosis was the most prevalent bronchial lesion. In total, 22% of benign lesions presented airway stenosis >50% and required bronchoscopic treatment. Bronchial stenosis was most frequently observed in tuberculosis (P=0.031) and aspergillosis (P=0.020) when compared with sarcoidosis. Immunosuppressive status was significantly associated with endobronchial aspergillosis (P=0.0001) and the 1-year survival from diagnosis resulted significantly lower irrespectively to the immune system condition.

CONCLUSIONS

A consistent proportion of endobronchial benign lesions are reported. One fifth of these are associated with critical stenosis of the airway lumen, requiring rigid bronchoscopy. Among these, aspergillosis is characterized by the poorest prognosis, regardless of host immunity status.

Clinical assessment of airway stent placement in patients with malignant airway lesions

Background

Airway stent placement has been proven as a satisfactory treatment of advanced malignant airway lesions. However, stent-related complications could impact the therapeutic effect of this treatment. This study aimed to assess the application of airway stents, including the clinical effects, and to explore high-risk factors for stent-related complications.

Methods

A retrospective cohort study of lung cancer (LC) patients and esophageal cancer (EC) patients was conducted at our center. Patients who received stent placement for malignant airway lesions from January 2014 to July 2017 were included in the study. Patient clinical status and stent-related complications, including granulation tissue formation, restenosis, atelectasis, migration, mucous plugging and infection were comprehensively analyzed.

Results

Fifty-six symptomatic patients who underwent 66 stent procedures were included. There was an immediate relief of symptoms after stent placement, and the Karnofsky Performance Status (KPS) scores significantly improved (56.67±23.52 versus 79.05±20.71; P<0.001). Among all the patients, general anesthesia (P=0.038) and pre-stent non-surgical therapy (P=0.048) were risk factors for granulation. A Charlson comorbidity index (CCI) <3 (P=0.008) and a procedure duration time >110 min (P=0.005) were associated with an increased risk of restenosis. Stent placement only in the main trachea (P=0.049) increased the risk of stent migration. Stent placement in the carina or upper airways (P=0.041) increased the risk of mucous plugging. The stent length (>60 mm) had a direct correlation with both mucous plugging in LC patients (P=0.003) and granulation tissue formation in EC patients (P=0.019).

Conclusions

Airway stent placement immediately and significantly improved the clinical symptoms for patients with advanced malignant airway lesions. High-risk factors for different stent-related complications were identified, which provided evidence for further clinical improvement with airway stents.

Central airway tumors: interventional bronchoscopy in diagnosis and management

The diagnosis of central airway tumors is usually challenging because of the vague presentations. Advances in visualization technology in bronchoscopy aid early detection of bronchial lesion. Cryotechnology has great impact on endobronchial lesion sampling and provides better diagnostic yield. Airway tumor involvements result in significant alteration in life quality and lead to poor life expectancy. Timely and efficiently use ablation techniques by heat or cold energy provide symptoms relief for central airway obstruction. Prostheses implantation is effective in maintaining airway patency after ablative procedure or external compression. Combined interventional bronchoscopy modalities and other adjunctive therapies have improvement in quality of life and further benefit in survival. This review aims to provide a diagnostic approach to central airway tumors and an overview of currently available techniques of interventional bronchoscopy in managing symptomatic central airway obstruction.

Stent-in-Stent Technique for the Treatment of Proximal Bronchial Restenosis after Insertion of Metallic Stents: A Report of Two Cases

Endoscopic treatment of a bronchial restenosis previously treated by insertion of a partially covered self-expandable metallic stent (SEMS) can be difficult. Classically, after recanalization of the bronchus, the stent is removed and replaced by a more adapted one. We report on two cases of proximal bronchial restenosis treated by insertion of an additional stent inside the lumen of the previously inserted stent using the stent-in-stent (SIS) technique. The indications for the initial stent were malignancy in Patient 1 and posttransplant bronchial stenosis in Patient 2. Restenosis occurred at the proximal end of the stent within months in both cases. Stent removal and insertion of a new stent were considered, but this option was discarded because of an excessive risk of bronchial perforation and preference towards an alternative approach. In both cases, a second customized SEMS was placed using the SIS technique after ablation of the proximal end stenosis of the stent by argon plasma coagulation and/or dilation with a balloon. Recanalization of the bronchus was achieved in both cases without complications. The SIS technique is a valuable alternative to removal of SEMS in case of proximal bronchial restenosis.

Tracheobronchial stents in mucopolysaccharidosis

INTRODUCTION

The mucopolysaccharidoses are a group of hereditary disorders pathologically characterized by tissue accumulation of glycosaminoglycans due to deficient lysosomal metabolism which often leads to progressive airway stenosis and respiratory insufficiency. Relentless and treatment-refractory narrowing of the lower airways with ensuing severe limitation of quality of life is a challenging problem in mucopolysaccharidoses.

CASE REPORTS

We report 2 cases of MPS (Hunter's and Maroteaux-Lamy's syndrome resp.) in whom tracheal stents were placed to relieve severe tracheal obstruction. The first patient could be weaned from mechanical ventilation after stent placement but showed significant long-term stent-related morbidity. The second patient suffered a severe procedure-related complication due to positioning problems typical for MPS.

CONCLUSIONS

Very good short-term success can be achieved with airway stent placement in patients with MPS and severe lower airway stenosis but a high risk of severe complications and important long-term morbidity have to be weighed against potential individual benefit.

Successful management of metallic expandable stent-associated tracheal restenosis by Montgomery T-tube insertion

OBJECTIVE

Tracheal stenosis can be life-threatening and has been seen with an increasing frequency.

METHODS

Metallic stent-associated stenosis remains a therapeutic challenge because of difficulty in tracheostomy.

RESULTS

Here, we report a case with repeated episodes of restenosis after insertion of metallic stents for benign tracheal stenosis which was successfully managed by Montgomery silicone T-tube placement.

CONCLUSION

We further reviewed the literature of reported cases of inappropriate use of metallic stent for benign diseases.