Advancements in airway stents: a comprehensive update

PURPOSE OF REVIEW

This review provides an overview of the evolving field of airway stenting (AS), highlighting its relevance in the management of central airway obstruction (CAO). It discusses recent advancements, including 3D-printed silicone stents (3DPSS), metallic stents, biodegradable stents (BS), and drug-eluting stents (DES), which are transforming clinical practice. The review underscores the ongoing challenges in patient selection, stent choice, and long-term management in the context of an evolving landscape.

RECENT FINDINGS

Innovations, particularly 3DPSS, have shown promise in providing patient-specific solutions. These stents offer improved symptom relief, enhanced quality of life, and lower complication rates, especially for complex airway diseases. The use of BS and DES is explored, raising prospects for future applications.

SUMMARY

The evolution of AS reflects a deepening understanding of airway obstructions. Recent innovations, such as 3DPSS, BS, and DES, show considerable promise in addressing the limitations of conventional stents. However, challenges related to complications, patient selection, and long-term management persist, demanding further research. Wide practice variations in the management of AS highlight the need for more clinical data and standardized guidelines. The search for the ideal stent continues, driven by the pursuit of better outcomes for patients with CAO.

Current Practices in Airway Stent Management: A National Survey of US Practitioners

BACKGROUND

Despite a growing number of tracheobronchial stent types and indications, complications remain frequent, and high-quality evidence on practices to prevent stent-related complications is lacking. Understanding current management practice is a first step to designing prospective studies to assess whether specific practices aimed at mitigating stent-related complications improve patient-centered outcomes.

OBJECTIVES

In this study, we aimed to understand current management strategies following tracheobronchial stenting.

METHOD

We performed a nationwide survey of members of the American Association of Bronchology and Interventional Pulmonology (AABIP) and the General Thoracic Surgical Club (GTSC) who place airway stents. The electronic survey captured data on practitioners' demographics, practice setting, airway stent volume, and standard post-stent practices (if any) including the use of medications, mucus clearance devices, surveillance imaging, and surveillance bronchoscopy.

RESULTS

One hundred thirty-eight physicians completed the survey. Respondents were majority male (75.4%) and had diverse training (50.0% completed interventional pulmonary fellowship; 18.1% thoracic surgery; 31.9% other stent training). Post-stent management strategies varied markedly across respondents; 75.4% prescribe at least one medication to prevent post-stent complications, 52.9% perform routine surveillance bronchoscopy in asymptomatic patients, 26.1% prescribe mucus clearance regimens, 16.7% obtain routine computed tomography scans in asymptomatic patients, and 8.3% routinely replace their stents prior to stent failure.

CONCLUSIONS

In this national survey of practitioners who place airway stents, there was marked heterogeneity in post-stent management approaches. Further studies are needed to identify which, if any, of these strategies improve patient-centered outcomes.

Forbearance with endobronchial stenting: cognisance before conviction

Endobronchial stenting is an important aspect of the practice of interventional pulmonology. The most common indication for stenting is the management of clinically significant airway stenosis. The list of endobronchial stents available on the market continues to grow. More recently, patient-specific 3D-printed airway stents have been approved for use. Airway stenting should be considered only when all other options have been exhausted. Due to the environment of the airways and the stent-airway wall interactions, stent-related complications are common. Although stents can be placed in various clinical scenarios, they should only be placed in scenarios with proven clinical benefit. The unwarranted placement of a stent can expose the patient to complications with little or no clinical benefit. This article reviews and outlines the key principles of endobronchial stenting and important clinical scenarios in which stenting should be avoided.

Identification of damage associated molecular patterns and extracellular matrix proteins as major constituents of the surface proteome of lung implantable silicone/nitinol devices

Lung implantable devices have been widely adopted as mechanical interventions for a wide variety of pulmonary pathologies. Despite successful initial treatment, long-term efficacy can often be impacted by fibrotic or granulation tissue formation at the implant sites. This study aimed to explore the lung-device interface by identifying the adhered proteome on lung devices explanted from patients with severe emphysema. In this study, scanning electron microscopy is used to visualize the adhesion of cells and proteins to silicone and nitinol surfaces of explanted endobronchial valves. By applying high-resolution mass-spectrometry, the surface proteome of eight explanted valves is characterized, identifying 263 unique protein species to be mutually adsorbed on the valves. This subset is subjected to gene enrichment analysis, matched with known databases and further validated using immunohistochemistry. Enrichment analyses reveal dominant clusters of functionally-related ontology terms associated with coagulation, pattern recognition receptor signaling, immune responses, cytoskeleton organization, cell adhesion and migration. Matching results show that extracellular matrix proteins and damage-associated molecular patterns are cardinal in the formation of the surface proteome. This is the first study investigating the composition of the adhered proteome on explanted lung devices, setting the groundwork for hypothesis generation and further exploration. STATEMENT OF SIGNIFICANCE: This is the first study investigating the composition of the adhered proteome on explanted lung devices. Lung implantable devices have been widely adopted as mechanical interventions for pulmonary pathologies. Despite successful initial treatment, long-term efficacy can often be impacted by fibrotic or granulation tissue formation around the implant sites. We identified the adhered proteome on explanted lung devices using several techniques. We identified 263 unique protein species to be mutually adsorbed on explanted lung devices. Pathway analyses revealed that these proteins are associated with coagulation, pattern recognition receptor signaling, immune responses, cytoskeleton organization, cell adhesion and migration. Furthermore, we identified that especially extracellular matrix proteins and damage-associated molecular patterns were cardinal in the formation of the surface proteome.

[Tracheobronchial stenting in patients with non-resectable tumors complicated by airway stenosis]

OBJECTIVE

To study the results and efficiency of tracheobronchial stenting in patients with unresectable tumors complicated by stenosis of central airways.

MATERIAL AND METHODS

We analyzed the results of tracheobronchial stenting in 23 patients with unresectable tumors complicated by stenosis of central airways between 2016 and 2021.

RESULTS

Technical and clinical success rate was 100%. No intraoperative complications were noted. Dyspnea regressed in all patients in early postoperative period. Moreover, there was objective improvement in lung ventilation with increase in lung capacity (from 2.1±0.4 to 2.7±0.5 l; p<0.05), forced expiratory volume (from 1.2±0.5 to 1.8±0.4 l; p<0.05), partial pressure of oxygen in arterial blood (from 47±7.4 to 85±6.3 mm Hg; p<0.05) and arterial oxygen saturation (from 86.1±8.2 to 93.1±5.1%; p<0.05). One patient developed massive bleeding due to tumor decay on the 3^rd day after surgery. In 2 patients, stent obturation with a «mucus plug» was observed after 2-3 postoperative days. In 3 months after surgery, 21.8% of patients had disturbances of external respiration accompanied by mild dyspnea due to granulation tissue growth. Stent migration in 3 months after endoscopic stenting was recorded in 1 patient. Three-month mortality was 26.1%.

CONCLUSION

Tracheobronchial stenting is a safe and effective minimally invasive surgical intervention. As a part of palliative care, this procedure improves functional and clinical parameters of pulmonary ventilation and reduces the incidence of complications. Thus, quality of life in patients with unresectable tumors complicated by airway stenosis is improved.

A Parametric Tool for Studying a New Tracheobronchial Silicone Stent Prototype: Toward a Customized 3D Printable Prosthesis

The management of complex airway disorders is challenging, as the airway stent placement usually results in several complications. Tissue reaction to the foreign body, poor mechanical properties and inadequate fit of the stent in the airway are some of the reported problems. For this reason, the design of customized biomedical devices to improve the accuracy of the clinical results has recently gained interest. The aim of the present study is to introduce a parametric tool for the design of a new tracheo-bronchial stent that could be capable of improving some of the performances of the commercial devices. The proposed methodology is based on the computer aided design software and on the finite element modeling. The computational results are validated by a parallel experimental work that includes the production of selected stent configurations using the 3D printing technology and their compressive test.

Placement of self-expanding metallic tracheobronchial Y stent with laryngeal mask airway using conscious sedation under fluoroscopic guidance

Background

Central airway obstruction and fistula are treated with a tracheobronchial Y stent. In the currently used self‐expandable metal Y stents, the delivery system is 8 mm in diameter and requires either a 9 mm tracheal tube or rigid bronchoscope to enable airway control during insertion. In this study we present a novel technique of laryngeal mask airway (LMA) assisted Y stent insertion, enabling airway control during deployment of the Y stent.

Methods

All procedures using LMA in assisting Y stent insertions between 2014–2020 were reviewed. Data collected included demographics, clinical diagnosis and disease characteristics, indication, procedural success rates, clinical outcome and survival.

Results

A total of 10 patients with a median age of 61.5 years (range 37–73) underwent LMA assisted Y stent insertion. Indications for stent insertion were malignant disease with central airway obstruction or fistula. In all cases airway patency was achieved leading to improvement of symptoms and performance status. No procedural complications were reported. The median survival was 4.5 weeks (range: 2–26).

Conclusions

LMA assisted Y stent insertion enables airway control during the procedure. In comparison to silicone Y stent insertion, the procedure is less cumbersome, shorter in duration and does not require the use of general anesthesia or rigid bronchoscopy.

Key points

Significant findings of the study

LMA assisted Y stent insertion enables airway control during the implantation of metallic self‐expanding Y stent. The procedure does not require the use of general anesthesia or rigid bronchoscopy.

What this study adds

In this study we present the technique and outcomes of LMA assisted Y stent insertion. This method of Y stent insertion provides an additional treatment option for patients with central airway obstruction and fistula.

Tracheobronchial stent sizing and deployment practices airway stenting practices around the world: a survey study

Background

Tracheobronchial stents types, uses, techniques for deployment and extraction have practice variations around the world.

Methods

We collected responses by sending an online survey of 8 questions to world interventional bronchology member societies and social media groups.

Results

There were 269 respondents from 47 countries. Europe had 97 respondents from 22 countries. There were 8 respondents from Australia, 7 from Africa (3 countries) and 7 from 4 countries in South America (SA). North America (NA) had 72 respondents from 3 countries. Asia had 78 respondents from 14 countries. For stent placements 15% [41] used fiberoptic bronchoscope (FB) only. Rigid bronchoscopy (RB) was solely utilized by 38% [102]. Forty-six percent [123] used a combination of RB and FB (P value <0.00001). For stent extraction 13% [19] used FB alone, 57% [85] used RB, and 36% [54] used a combination of RB and FB (P value <0.00001). Placement of stents were 50.5% [135] only by direct visualization. Twenty-three percent [61] always used fluoroscopic guidance. Twenty-six-point-five percent [71] used fluoroscopy in certain cases (P value <0.00001). Sixty percent [162] decided stent sizing by measurements of stenotic and non-stenotic areas on radiology. Twelve percent [32] respondents used sizing devices. Sixty-five percent [177] used a ruler and bronchoscope to measure stenotic areas. Thirty-eight percent [104] used visual estimation and experience. Seven percent [19] used serial balloon dilatation size. To prevent clogging of stents, 22% [59] prescribed mucolytics. Seventy-three percent [195] nebulized saline, 26% [70] had Mucomyst Nebulization, 24% [65] Nebulized bronchodilators and other methods 11% [30] were advised. Covered self-expandable metal stents (SEMS) 44% was the commonest type of stent used around the world. Silicone stents 37%, Y stents 15%, uncovered SEMS 12%, Montgomery T tube 5% followed. Polyflex stents 3% and custom-made stents 3% were least used. Biodegradable stents were used by 7.5%, and not used by 92.5%.

Conclusions

Tracheobronchial stent practice norms have slowly evolved, but its practice variations lack uniformity, and have sparse evidence-based studies for its direction.

Self-expanding metallic Y-stent compared to silicone Y-stent for malignant lesions of the main carina: A single center retrospective study

BACKGROUND

Bifurcation stents are often required in patients with malignant airway obstruction or fistulization involving the main carina. The silicone Y stent is the most used but remains challenging to place. The self-expanding metallic Y (SEM) stent appears easy to use. The objective is to report the feasibility, efficacy, and tolerance of SEM Y stent compared to silicone Y stent in patients with malignant tumors involving the main carina.

PATIENTS AND METHODS

This retrospective single center study was performed between May 2004 and May 2017. All patients with malignant carina involvement treated with a bronchial Y stent were included.

RESULTS

Forty silicone Y stents and 38 SEM Y stents were placed. Seven stenting placements failed in the silicone Y group but none in the SEM Y stent group (P=0.008). The median duration of the procedure was 80min (25-210) in the silicone Y group and.50min (25-110min) in the SEM Y group (P=0.001). There was no significant difference in terms of early or late complications between the 2 groups. Nine silicone Y stents (26.5%) and 7 SEM Y stents (18.4%) were removed (P=0.4). The median survival time following stent insertion was 171 days (Interquartile range (IQR): 53-379) in the silicone Y group and 104 days (IQR: 53-230) in the SEM Y group.

CONCLUSION

If silicone Y stent remains the best solution for benign obstruction, SEM Y stent seems to be an easy alternative with no difference in terms of complication or ablation for malignant lesions involving the main carina.

Airway stenting: Technological advancements and its role in interventional pulmonology

AS offers rapid and sustained relief of symptoms in most patients treated for malignant or benign CAO and can also be curative in itself in cases of benign tracheobronchial stenosis. In the past 30 years, this field has seen significant progress, from the misuse of vascular non-covered metallic stents to the development of silicone airway stents with an increasingly large panel of shapes and of hybrid, partially or fully covered, SEMS customized to the airways. This study aims to offer an overview on: (i) the respective advantages and drawbacks of these two main categories of devices; (ii) the main indications for AS and the rationale behind the choice of stent in each situation; and (iii) the main promises borne from the progress made in the field in the past few years, including the development of drug-eluting, biodegradable or patient-specific customized AS.

Magnetic resonance imaging of patients with airway stents

Airway stent implantation is a highly effective treatment for airway stenosis. However, it is presently unclear whether patients with airway stents can safely undergo magnetic resonance imaging (MRI). Such stents may be metallic or non-metallic, and MRI may induce stent dislodgment or heating and may be associated with stent-induced artifacts. We thoroughly reviewed the literature, experimental data, and manufacturer information on non-metallic, stainless steel (SS) and nickel-titanium alloy stents. Non-metallic stents are made of non-ferromagnetic materials associated with no MRI concerns. SS stents may shift in a magnetic field, generating significant artifacts. Nickel-titanium alloy stents are not at risk of dislodgement or heating, but may create some artifacts affecting image quality. Both non-metallic and nickel-titanium alloy stents are safe for patients who must undergo MRI. However, the safety of SS stents depends on the type of steel used.