Respiratory infections increase the risk of granulation tissue formation following airway stenting in patients with malignant airway obstruction

World Association for Bronchology and Interventional Pulmonology (WABIP) guidelines on airway stenting for malignant central airway obstruction

Malignant Central Airway Obstruction (MCAO) encompasses significant and symptomatic narrowing of the central airways that can occur due to primary lung cancer or metastatic disease. Therapeutic bronchoscopy is associated with high technical success and symptomatic relief and includes a wide range of airway interventions including airway stents. Published literature suggests that stenting practices vary significantly across the world primarily due to lack of guidance. This document aims to address this knowledge gap by addressing relevant questions related to airway stenting in MCAO. An international group of 17 experts from 17 institutions across 11 countries with experience in using airway stenting for MCAO was convened as part of this guideline statement through the World Association for Bronchology and Interventional Pulmonology (WABIP). We performed a literature and internet search for reports addressing six clinically relevant questions. This guideline statement, consisting of recommendations addressing these six PICO questions, was formulated by a systematic and rigorous process involving the evaluation of published evidence, augmented with expert experience when necessary. Panel members participated in the development of the final recommendations using the modified Delphi technique.

Analyzing the characteristics of respiratory microbiota after the placement of an airway stent for malignant central airway obstruction

Malignant central airway stenosis is treated with airway stent placement, but post-placement microbial characteristics remain unclear. We studied microbial features in 60 patients post-stent placement, focusing on changes during granulation tissue proliferation. Samples were collected before stent (N = 29), after stent on day 3 (N = 20), and after granulation tissue formation (AS-GTF, N = 43). Metagenomic sequencing showed significant respiratory tract microbiota changes with granulation tissue. The microbiota composition, dominated by Actinobacteria, Firmicutes, and Proteobacteria, was similar among the groups. At the species level, the AS-GTF group exhibited significant differences, with Peptostreptococcus stomatis and Achromobacter xylosoxidans enriched. Analysis based on tracheoesophageal fistula presence identified Tannerella forsythia and Stenotrophomonas maltophilia as the main differential species, enriched in the fistula subgroup. Viral and fungal detection showed Human gammaherpesvirus 4 and Candida albicans as the main species, respectively. These findings highlight microbiota changes after stent placement, potentially associated with granulation tissue proliferation, informing stent placement therapy and anti-infective treatment optimization.

IMPORTANCE

Malignant central airway stenosis is a life-threatening condition that can be effectively treated with airway stent placement. However, despite its clinical importance, the microbial characteristics of the respiratory tract following stent insertion remain poorly understood. This study addresses this gap by investigating the microbial features in patients with malignant central airway stenosis after stent placement, with a specific focus on microbial changes during granulation tissue proliferation. The findings reveal significant alterations in the diversity and structure of the respiratory tract microbiota following the placement of malignant central airway stents. Notably, certain bacterial species, including Peptostreptococcus stomatis and Achromobacter xylosoxidans, exhibit distinct patterns in the after-stent granulation tissue formation group. Additionally, the presence of tracheoesophageal fistula further influences the microbial composition. These insights provide valuable references for optimizing stent placement therapy and enhancing clinical anti-infective strategies.

[Tracheal Tumours]

Malignant primary tracheal tumours are rare. The most common histological subtypes are squamous cell carcinoma and adenoid cystic carcinoma. These two entities have different prognoses and growth patterns. Tracheobronchoscopy and thoracic sectional imaging are standard diagnostic tools for tumour staging and local evaluation. Complete surgical resection of the affected tracheal segment is the treatment of choice for limited disease without distant metastases. Incomplete gross tumour resection with additional irradiation is an acceptable therapeutic option for adenoid cystic carcinoma. Interventional endoscopy with tumour debulking or tracheal stenting and/or definitive mediastinal radiotherapy are treatment alternatives in either a locally advanced or palliative setting.

Airway stent intervention in a high-volume center: safe procedures and educational perspectives

Background

Airway intervention, including stenting, can rapidly improve a patient's respiratory condition, but the procedure requires highly specialized techniques and expertise. Therefore, educating young endoscopists and passing on the techniques are major issues. However, the best way to educate new doctors on these techniques remains unclear. This study analyzed our educational system for airway intervention and its outcomes.

Methods

Patients who underwent airway intervention regarding airway stents under general anesthesia in our department between January 2010 and September 2023 were included. The outcomes of interventions related to airway stents in our hospital were evaluated retrospectively, including from an educational perspective.

Results

A total of 96 patients (76 undergoing stenting for airway stenosis, 8 stenting for airway-esophageal fistula, and 12 stent removal) were analyzed. The median experience level of the main physician was 5 (range, 1-17) years, and that of the supervising physician was 18 (range, 5-23) years. The median number of physicians who participated in the interventions was four. A rigid bronchoscope was used in 86.5% of cases. The procedure success rate was 95.8%. Intraoperative complications occurred in 8.3% and postoperative complications in 10.5% of cases, and there was 1 procedure-related death (1.3%). In the analysis of factors related to the development of complications, the years of experience of the main physician had no influence.

Conclusions

These findings indicate that our method of airway intervention is safe. Young endoscopists were able to master the technique by gaining experience under the supervision of experts.

To Compare the Effects of a Standard Versus Hydrophilic Polymer Coated Airway Stent in a Porcine Model: A Randomized, Single-Blinded Study

BACKGROUND

Stent encrustation with debris and mucostasis is a significant cause of airway injury and comorbidity, leading to ~25% of stent exchanges (1-3). Previous work from our group has shown that the experimental coating can reduce mucous adhesion in bench testing and demonstrated a signal for reducing airway injury and mucostasis in a feasibility study.

OBJECTIVES

The aim of this study is to continue our inquiry in a randomized, single-blinded multi-animal trial to investigate the degree of airway injury and mucostasis using silicone stents with and without this specialized coating.

METHODS

We modified commercially available silicone stents with a hydrophilic polymer from Toray Industries. We conducted an in vivo survival study in 6 mainstem airways (3 coated and 3 uncoated) of 3 pigs to compare the degree of airway injury and mucostasis between coated versus noncoated stented airways. Both stents were randomized to either left or right mainstem bronchus. The pathologist was blinded to the stent type.

RESULTS

We implanted a total of six 14×15 mm silicone stents (1 per mainstem bronchi) into 3 pigs. All animals survived to termination at 4 weeks. All stents were intact; however, 1 uncoated stent migrated out. On average, all the coated stents demonstrated reduced pathology and tissue injury scores (75 vs. 68.3, respectively). The average total dried mucous weight was slightly higher in the coated stents (0.07 g vs. 0.05 g; respectively).

CONCLUSION

Coated stents had lower airway injury compared with uncoated stents in this study. Of all the stents, 1 uncoated stent migrated out and was not included in the dried mucous weight totals. This could explain the slightly higher mucous weight in the coated stents. Nevertheless, this current study demonstrates promising results in lowering airway injury in stents incorporated with the hydrophilic coating, and future studies, including a larger number of subjects, would be needed to corroborate our findings.

Study on the rationality of small diameter metallic airway stent in treatment of tracheal stenosis in injured rabbits

BACKGROUND

To observe the occurrence of related complications after self-expandable metallic (SEM) airway stents implantation with different diameters at different time points, and to provide theoretical basis for the optimal chioce of existing airway stents in clinical practice.

METHODS

Healthy New Zealand white rabbits were used to establish benign tracheal stenosis models after chest CT examination. Forty-fivemodel rabbits with more than 50% of airway stenosis were divided into two groups. Small-diameter SEM stents (The ratio of stent diameter to airway diameter is nearly 1.0) were implanted in Group A in 21 rabbits, and large-diameter tracheal stents (The ratio of stent diameter to airway diameter is more than 1.2) were implanted in Group B in 24 rabbits. Stent-related complications were observed after stent implantation in 2nd,4th,8th, and 12th week by bronchoscopygross anatomy, pathological and the expressions of IL-1RA, IL-8 and MMP9 in involved tracheal.

RESULTS

The incidence rate of tracheomalacia of stent was significantly higher in group B (24/24 100%) than that in group A (1 /21,4.8%) (P < 0.05). The incidence rate of scar contracture at both ends of stent was significantly higher than in group B (11 / 24,45.8%) that in group A (2 /21, 9.5%) (P < 0.05). The pathological results of both A and B showed that the columnar epithelium of bronchial mucosa began to damage and detach, inflammatory cells infiltrated after 2nd and 4th week of stenting, The epithelium was repaired, the lamina propria glands almost disappeared, collagen fiber proliferation was obvious, and scars were formed after 8th and 12th week of stenting. ELISA results revealed that the expressions of IL-1RA, IL-8, and MMP9 were increased in the stent group than in model rabbit with benign tracheal stenosis. IL-1RA and MMP9 increased at different periods in group B, but the expression of IL-1RA and MMP9 showed a tread of increasing in the early stage and then decreasing in group A.

CONCLUSION

Metal stents can cause different degrees of stent-related complications in rabbits with benign tracheal stenosis. The incidence of stent-induced tracheomalacia and scar contracture were higher in Group B than that in Group A. IL-1RA, IL-8 and MMP9 may be involved in the development of complications after stentimplantation and peak value of group B movered backward. ing.

Effectiveness of AERO Stent Placement for Malignant Airway Disorder in Patients with a Poor Performance Status

Objective Airway stenting is an established procedure for treating various airway disorders. The AERO stent (Merit Medical Systems, South Jordan, UT, USA) is a fully covered self-expandable metallic stent approved for use in Japan in 2014. However, its effectiveness in treating malignant airway disorders in patients with a poor performance status remains unclear. Therefore, we investigated the safety and efficacy of the AERO stent in patients with malignant airway disorders and a poor performance status. Patients and Methods We retrospectively reviewed the medical records of all patients who underwent AERO stent placement at our institute between April 2016 and March 2022, and 21 patients underwent 25 procedures for malignant airway disorders. All AERO stenting procedures were performed using an over-the-wire delivery system with flexible and/or rigid bronchoscopy. Results Eighteen of the 21 patients (85.7%) had a poor general condition (Eastern Cooperative Oncology Group performance status 3 or 4). AERO stents were successfully placed in 23 of the 25 procedures and migrated in the remaining 2 cases. Complications occurred in 10 cases, with infection being the most common (3 cases). Fourteen patients (66.6%) showed an improvement in their performance status. In addition, 5 of the 6 intubated patients were extubated following AERO stenting, and 11 patients subsequently received anticancer treatment. Conclusion The placement of the AERO stent is useful in patients with a poor performance status, including those who are intubated and afflicted with malignant airway disorders.

Microinjection Molded Biopolymeric Airway Stent with Antibacterial and Anti-Hyperplastic Properties

Central airway stenosis is a condition that the diameter of the trachea or main bronchus shrinkage is caused by external compression or internal tissue hyperplasia, which can cause difficulty breathing, asphyxia, and even death. Airway stenting is an easy way to restore the patency of the central airway, but airway stents commonly used in clinical practice can lead to complications such as mucus plugging, bacterial infection, and granulation tissue hyperplasia. Moreover, the non-degradable characteristic makes it requires a second operation to remove, which has the potential to cause tissue damage. In this study, a biodegradable airway stent is fabricated by microinjection molding using the bioelastomer of poly (L-lactide-co-ε-caprolactone) as the matrix material. The airway stent has excellent mechanical properties and an appropriate degradation rate. The hydrophilic surface of the airway stent can inhibit mucus plugging. The loading of silver nanoparticles and cisplatin endows the stent with antibacterial and anti-hyperplastic functions. In vitro and in vivo experiments demonstrate that this study provides an antibacterial and anti-hyperplastic biodegradable airway stent with elastic properties to avoid secondary removal operation and reduce complications associated with mucus plugging, bacterial infection, and granulation tissue hyperplasia.

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.

Fatal Stent-Associated Respiratory Tract Infection Caused by K64-ST11 KPC-2-Producing Carbapenem-Resistant Hypervirulent Klebsiella pneumoniae: A Rare Case Report

Objectives: This study reported a fatal stent-associated respiratory tract infection (SARTI) caused by carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP). Case: A bare-metal stent in the left main bronchus and a Y-shaped stent graft in the tracheal bronchus were placed successively in a 50-year-old woman due to shortness of breath after undergoing multiple chemotherapy treatments for lung cancer. Unfortunately, the followed SARTI and lung abscess in our patient caused by CR-hvKP eventually led to the death of the patient, despite our aggressive clearing of phlegm and potent antibiotics. The genomic analysis showed it was caused by a KPC-2-producing extensively drug-resistant K64-ST11 hypervirulent K. pneumoniae harboring several virulence and antimicrobial resistance genes. Conclusion: This study highlights the risk of SARTI caused by CR-hvKP in immunocompromised individuals.

Establishing a novel model of malignant airway stenosis in rabbit

Background

Malignant central airway stenosis is a life-threatening condition. However, treatment of malignant airway stenosis remains challenging. There is currently a severe lack of an excellent animal model of malignant airway stenosis to facilitate treatment approaches. This is the first study to establish a rabbit model of malignant airway stenosis for bronchoscopic interventional studies.

Materials and methods

New Zealand White rabbits were used in this study, randomly divided into group A (18 rabbits) and group B (6 rabbits). A VX2 fragment suspension was injected into the submucosal layer of rabbits’ airway by bronchoscopy. Bronchoscopic examinations were performed once a week after VX2 tumor implantation to observe tumor growth and the degree of airway stenosis. Randomly, three rabbits were generally dissected after a weekly bronchoscopic examination in group A. The rabbits that reached grade III airway stenosis underwent stent implantation in group B.

Results

A total of 24 rabbits were successfully implanted with the VX2 fragment suspension in the airway without significant adverse events, and the success rate of the tumor growth was 100%. The degree of airway stenosis reaching grade III took 2 to 3 weeks after implantation of the VX2 tumor. The median survival time of rabbit models without stent implantation and rabbits with stent implantation was 32.5 and 32.0 days, respectively.

Conclusions

The implanting method is safe and effective for the establishment of a rabbit model of malignant airway stenosis. When the tumor grows to 2 to 3 weeks, the rabbit model is available for stent implantation. We recommend the models for more preclinical animal studies on bronchoscopic interventional treatments.

Therapeutic bronchoscopy for malignant central airway obstruction: impact on quality of life and risk-benefit analysis

PURPOSE OF REVIEW

Malignant central airway obstruction (CAO) is a common complication in cancer and confers significant symptom burden and reduction in quality of life. Multiple bronchoscopic interventions exist for malignant CAO. In this review, we discuss the role of therapeutic bronchoscopy in the management of malignant CAO, emphasizing its impact on symptom control and quality of life while balancing the risks and benefits of intervention.

RECENT FINDINGS

Significant practice variations exist among practitioners of therapeutic bronchoscopy, and limited data exist to guide real-time clinical decision-making. Recent analyses demonstrate that therapeutic bronchoscopy is effective for symptoms associated with malignant CAO with infrequent complications. These studies also show that many of the improvements in symptoms and quality of life are sustained after intervention and are associated with improved overall survival in patients with malignant CAO. Recent data have also shown that the improvement in symptoms associated with therapeutic bronchoscopy may enable more definitive cancer treatment, further improving patient outcomes.

SUMMARY

Therapeutic bronchoscopy is safe and effective at improving patient-centered outcomes in malignant CAO. Research is ongoing to better understand its optimal role in this setting, refine decision-making regarding advanced bronchoscopic interventions, and further improve patient outcomes.

Malignant Central Airway Obstruction: What's New?

Malignant central airway obstruction (MCAO) is a debilitating and life-limiting complication that occurs in an unfortunately large number of individuals with advanced intrathoracic cancer. Although the management of MCAO is multimodal and interdisciplinary, the task of providing patients with prompt palliation falls increasingly on the shoulders of interventional pulmonologists. While a variety of tools and techniques are available for the management of malignant obstructive lesions, advancements and evolution in this therapeutic venue have been somewhat sluggish and limited when compared with other branches of interventional pulmonary medicine (e.g., the early diagnosis of peripheral lung nodules). Indeed, one pragmatic, albeit somewhat uncharitable, reading of this article's title might suggest a wry smile and shug of the shoulders as to imply that relatively little has changed in recent years. That said, the spectrum of interventions for MCAO continues to expand, even if at a less impressive clip. Herein, we present on MCAO and its endoscopic and nonendoscopic management-that which is old, that which is new, and that which is still on the horizon.

Vancomycin-Loaded Polycaprolactone Electrospinning Nanofibers Modulate the Airway Interfaces to Restrain Tracheal Stenosis

Site-specific release of therapeutics at the infected trachea remains a great challenge in clinic. This work aimed to develop a series of vancomycin (VA)-loaded polycaprolactone (PCL) composite nanofiber films (PVNF-n, n = 0, 1, and 5, respectively) via the electrospinning technique. The physiochemical and biological properties of PVNF-n were evaluated by a series of tests, such as FT-IR, XRD, SEM-EDS, and antibacterial assay. The PVNF-n samples displayed a typical network structure of fibers with random directions. VA was successfully introduced into the PCL nanofibers and could be sustained and released. More importantly, PVNF-5 showed relatively good antibacterial activity against both methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae (SPn). Thus, PVNF-5 was covered onto the self-expandable metallic stent and then implanted into a New Zealand rabbit model to repair tracheal stenosis. Compared to a metallic stent, a commercial pellosil matrix–covered stent, and a PVNF-0–covered metallic stent, the PVNF-5–covered airway stent showed reduced granulation tissue thickness, collagen density, α-SMA, CD68, TNF-α, IL-1, and IL-6 expression. In conclusion, this work provides an anti-infection film–covered airway stent that in site restrains tracheal stenosis.

Synergistic effects of silver nanoparticles and cisplatin in combating inflammation and hyperplasia of airway stents

Anti-inflammatory and antihyperplasia activities are essential requirements for the successful use of airway stents. In this work, silver nanoparticles (AgNPs) and cisplatin (DDP) were combined in a synergistic modification strategy to improve the surface function of airway stents. Using polycaprolactone (PCL) as a drug carrier, a dual-functional PCL-AgNPs-DDP fiber film-coated airway stent was fabricated by electrospinning. The physicochemical and biological properties of the obtained fiber films were examined. The ATR-FTIR, XPS, SEM-EDS and TEM results suggested that AgNPs and DDP could be successfully immobilized onto the airway stent surface. The drug release and surface degradation results revealed that AgNPs and DDP can undergo sustained release from films for 30 d, and the weight loss was approximately 50% after 35 d. In addition, the dual-functional fiber film suppressed human embryonic lung fibroblast growth and exhibited excellent antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. Furthermore, the effectiveness of the dual-functional fiber film-coated airway stent was evaluated by application to the trachea of New Zealand rabbits. The in vivo results indicated that PCL-AgNPs-DDP fiber film-coated airway stent can significantly inhibit granulation tissue formation and collagen deposition, reduced the expression of IL-8, TNF-α, IL-1α, PCNA, α-SMA and CD68, and ultimately achieved anti-inflammatory and antihyperplasia effects. Hence, this study provides a dual-functional surface-coated airway stent to address the clinical complications associated with respiratory tract inflammation and granulation tissue hyperplasia, thus inhibiting tracheal stenosis.

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This study provides a dual-functional PCL-AgNPs-DDP nanofiber film-coated airway stent.

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The airway stent processes antibacterial activity and suppress CCC-HPF-1 growth.

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The stent inhibits tracheal stenosis by antiinflammatory and antihyperplasia treatment.

Risk-score model to predict prognosis of malignant airway obstruction after interventional bronchoscopy

Background

Interventional bronchoscopy exhibits substantial effects for patients with malignant airway obstruction (MAO), while little information is available regarding the potential prognostic factors for these patients.

Methods

Between October 31, 2016, and July 31, 2019, a total of 150 patients undergoing interventional bronchoscopy and histologically-confirmed MAO were collected, in which 112 eligible participants formed the cohort for survival study. External validation cohort from another independent institution comprised 33 MAO patients with therapeutic bronchoscopy. The least absolute shrinkage and selection operator regression (LASSO) was applied to the model development dataset for selecting features correlated with MAO survival for inclusion in the Cox regression from which we elaborated the risk score system. A nomogram algorithm was also utilized.

Results

In our study, we observed a significant decline of stenosis rate after interventional bronchoscopy from 71.7%±2.1% to 36.6%±2.7% (P<0.001) and interventional bronchoscopy dilated airway effectively. Patients in our study undergoing interventional bronchoscopy had a median survival time of 614.000 days (95% CI: 269.876–958.124). Patients receiving distinct therapeutic methods of interventional bronchoscopy had different prognosis (P=0.022), and patients receiving treatment of electrocoagulation in combination with stenting and electrosurgical snare had worse survival than those receiving other options. Multivariate Cox analysis revealed that nonsmoking status, adenoid cystic carcinoma, and low preoperative stenosis length, as independent predictive factors for better overall survival (OS) of MAO patients. Then, the nomogram based on Cox regression and risk score system based on results from LASSO regression were elaborated respectively. Importantly, this risk score system was proved to have better performance than the nomogram and other single biomarkers such as traditional staging system (area under the curve 0.855 vs. 0.392–0.739). Survival curves showed that patients with the higher risk-score had poorer prognosis than those with lower risk-score (third quantile of OS: 126.000 days, 95% CI: 73.588–178.412 vs. 532.000 days, 95% CI: 0.000–1,110.372; P<0.001).

Conclusions

Nonsmoking status, adenoid cystic carcinoma, and low preoperative stenosis length, were independent predictive factors for better OS of MAO patients. We proposed a nomogram and risk score system for survival prediction of MAO patients undergoing interventional bronchoscopy with good performance.

Airway granulation response to lung-implantable medical devices: a concise overview

Increasing numbers of endoscopically implantable devices are implanted in the airways, such as airway stents, one-way valves and coils, to treat both malignant and benign diseases. They significantly improve patient outcomes, but their long-term effectiveness and sustainability is hampered by the reaction of the formation of granulation tissue. Factors including procedural-related tissue injury; micro-organism presence; device-related factors, such as the material, design and sizing in relation to the airway; and patient-related factors, including genetic susceptibility, comorbidities and medication use, might all effect the severity of the tissue response and the subsequent degree of granulation tissue formation. However, research into the underlying mechanism and risk factors is scarce and therefore our knowledge is limited. Joint efforts from the scientific community, both pre-clinical and clinical, are needed to gain a deeper understanding and eventually improve the long-term treatment effectiveness of lung-implantable devices.

Medical implantable devices are increasingly used in pulmonary medicine. Complications related to the tissue–device interaction are often present, but our knowledge of the underlying processes is limited.https://bit.ly/2RdWVkG

The (Hour)glass Half-Full: Modified Silicone Hourglass Stents for the Treatment of Central Airway Obstruction

Central airway obstruction often presents with airway narrowing of differing internal diameters. Conventional straight stents do not fit these airways well and are prone to migration. We present a series of cases where hourglass-shaped silicone stents were customized intra-operatively to fit airway obstructions of both malignant and non-malignant etiologies and to improve patient performance status. Modified hourglass stents are a versatile tool to manage inoperable airway obstruction with unique anatomical characteristics.

Long-term outcomes of metallic endobronchial stents in lung transplant recipients are not affected by bacterial colonization

OBJECTIVES

We evaluated associations of endobronchial stenting with airway bacterial colonization, the antimicrobial resistance profile, hospitalizations for pneumonia and survival in lung transplant recipients.

METHODS

This is a retrospective single-centre study of 582 recipients of lung transplant during 2002-2018. We compared outcomes of 57 patients (9.7%) who received endobronchial stents (intervention group) to a control group of 57 patients without stents who were matched one to one for age, sex, year of transplantation, unilateral/bilateral transplantation and underlying disease.

RESULTS

For the intervention compared to the control group, airway colonization was more common for Pseudomonas (86% vs 35%, P < 0.001), Acinetobacter (21% vs 7%, P = 0.05), Klebsiella (21% vs 5%, P = 0.02) and Staphylococcus species (11% vs 0%, P = 0.02). The respective proportions of patients with positive bronchoalveolar lavage cultures on the third post-transplantation day, the day of stent insertion and 6-month post-stent insertion were 47.4%, 50.9% and 65.4% for Pseudomonas sp.; 15.8%, 12.3% and 3.8% for Klebsiella sp.; and 8.8%, 5.3% and 5.8% for Acinetobacter sp. The mean number of hospitalizations for pneumonia per patient was higher, without statistical significance, in the intervention than the control group (1.5 ± 1.7 vs 0.9 ± 1.5, P = 0.1). Kaplan-Meier survival curves did not show a statistically significant difference between the intervention group and the entire group without endobronchial stents (n = 525) (P = 0.4).

CONCLUSIONS

Lung transplant recipients with endobronchial stents were more likely to be colonized with pathologic bacteria and having pneumonia; however, stent placement was not associated with increased long-term mortality with appropriate stent maintenance.

Contributions of Airway Stent for Long-term Outcome in Patients With Malignant Central Airway Stenosis or Obstruction

BACKGROUND

Although an airway stent is used for malignant central airway stenosis or obstruction, long-term outcomes are unknown. In this study, we retrospectively analyzed the clinical features of patients who required stenting for malignant central airway stenosis or obstruction.

PATIENTS AND METHODS

We retrospectively analyzed clinical data from 116 patients with stenting for central airway stenosis or obstruction who underwent treatment at Toho University Hospital from 1998 to 2018. We evaluated the clinical features, prognoses, and complications for stenting in these patients.

RESULTS

The distribution of the 116 patients was as follows: lung cancer, 53; esophageal cancer, 40; thyroid cancer, 8; and others, 15. Patients with thyroid cancer had a significantly higher rate of complications after stenting than patients with lung cancer (P=0.0062), esophageal cancer (P=0.0029), and others (P=0.0062). Patients with esophageal cancer had a significantly worse prognosis than patients with lung and thyroid cancer. In patients with lung cancer the prognosis was significantly different between patients who underwent additional treatment for lung cancer after stenting and patients with no treatment (P=0.0398), and patients who received chemoradiotherapy for lung cancer after stenting had a significantly better prognosis than patients with no treatment (P=0.0306).

CONCLUSION

Stenting for airway stenosis/obstruction may improve prognosis in patients with lung or thyroid cancer, especially if patients with lung cancer undergo additional treatments after stenting, although airway stenting for patients with esophageal cancer was palliative. New treatment strategies may be necessary for patients with esophageal cancer after stenting to improve prognosis.

Is rigid tracheobronchoscopy safe enough for airway disease?

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Revision Bronchoscopy After Endobronchial Valve Treatment for Emphysema: Indications, Findings and Outcomes

Background

Endobronchial valve (EBV) treatment is an effective treatment for patients with severe emphysema. Revision bronchoscopies after endobronchial valve treatment can be essential to prolong the effect of treatment or address long-term complications.

Purpose

To evaluate the indications, endoscopic findings and outcomes of revision bronchoscopies and investigate if any predictors for granulation tissue formation, after EBV treatment, can be identified.

Patients and Methods

Patients who underwent EBV treatment between 2016 and 2019 in our hospital, as routine care, were included. If a patient underwent a revision bronchoscopy, data regarding revision bronchoscopies, including indication, finding, intervention and pulmonary function testing (PFT) after revision bronchoscopy were analysed.

Results

One hundred seventy-nine patients were included of which 41% required at least one revision bronchoscopy. In 43% of the revision bronchoscopy patients, the indication was loss of initial treatment effect. In 53% of the revision bronchoscopy patients, granulation tissue was found to be the underlying cause. Valve replacement(s) were performed in 51% of the revision bronchoscopy cases. Permanent valve removal was required in 13% of all patients. Overall, revision bronchoscopies led to improvements in PFT outcomes for patients experiencing no or a loss of initial treatment effect. No clinically relevant predictors for granulation tissue formation were identified.

Conclusion

Performing a revision bronchoscopy after EBV treatment is a useful procedure leading to an improved treatment effect in most patients. Granulation tissue formation, causing valve dysfunction, is the most common cause of longer term problems.

Long-term survival of airway silicone stents in patients with central airway stenosis or obstruction due to thoracic malignancy

OBJECTIVES

Silicone airway stents are used to manage central airway stenosis or obstruction, although their impact on long-term survival remains unknown in patients with central airway stenosis or obstruction due to thoracic malignancy. In this study, we retrospectively analyzed the impact of silicone stents on survival.

METHODS

We retrospectively analyzed clinical data of 106 patients with central airway stenosis or obstruction due to thoracic malignancy treated by stenting at Toho University Omori Medical Center between 1998 and 2018.

RESULTS

Patients treated with silicone stents had significantly higher survival rates than patients treated with metallic stents (p = 0.0173). Silicone stents patients also had significantly more additional treatments for thoracic malignancy after stenting than metallic stents patients (p = 0.0007). Notably, significantly more silicone stents patients underwent chemoradiotherapy or radiotherapy (p = 0.0268, p = 0.0300). During multivariate analyses, the additional treatment, including chemoradiotherapy or radiotherapy, was an independent optimal prognostic factor.

CONCLUSIONS

Silicone stents patients had significantly higher survival rates than metallic stents patients. Although stenting for airway stenosis or obstruction due to thoracic malignancy may be mainly palliative, additional treatments after stenting should be considered to improve the prognoses of patients with airway stenosis or obstruction due to thoracic malignancy.

Arsenic trioxide-eluting electrospun nanofiber-covered self-expandable metallic stent reduces granulation tissue hyperplasia in rabbit trachea

Stent-related granulation tissue hyperplasia is a major complication that limits the application of stents in airways. In this study, an arsenic trioxide-eluting electrospun nanofiber-covered self-expandable metallic stent (ATO-NFCS) was developed. Poly-L-lactide-caprolactone (PLCL) was selected as the drug-carrying polymer. Stents with two different ATO contents (0.4% ATO/PLCL and 1.2% ATO/PLCL) were fabricated. The in vitro release in simulated airway fluid suggested that the total ATO release time was 1 d. The growth of human embryonic pulmonary fibroblasts (CCC-HPF-1), normal human bronchial epithelial cells and airway smooth muscle cells was inhibited by ATO. When embedded in paravertebral muscle, the nanofiber membrane showed good short-term and long-term biological effects. In an animal study, placement of the ATO-NFCS in the trachea through a delivery system under fluoroscopy was feasible. The changes in liver and kidney function 1 and 7 d after ATO-NFCS placement were within the normal range. On pathological examination, the heart, liver, spleen, lungs and kidneys were normal. The effectiveness of the ATO-NFCS in reducing granulation tissue hyperplasia and collagen deposition was demonstrated in the rabbit airway (n = 18) at 4 weeks. The present study preliminarily investigated the efficacy of the ATO-NFCS in reducing granulation tissue formation in the trachea of rabbits. The results suggest that the ATO-NFCS is safe in vivo, easy to place, and effective for the suppression of granulation tissue formation.

Using individualized three-dimensional printed airway models to guide airway stent implantation

Airway stents are used to manage central airway obstructions by restoring airway patency. Current manufactured stents are limited in shape and size, which pose issues in stent fenestrations needed to be manually created to allow collateral ventilation to airway branches. The precise location to place these fenestrations can be difficult to predict based on 2-dimensional computed tomography images. Inspiratory computed tomography scans were obtained from 3 patients and analysed using 3D-Slicer™, Blender™ and AutoDesk® Meshmixer™ programmes to obtain working 3D-airway models, which were 3D printed. Stent customizations were made based on 3D-model dimensions, and fenestrations into the stent were cut. The modified stents were then inserted as per usual technique. Two patients reported improved airway performance; however, stents were later removed due to symptoms related to in-stent sputum retention. In a third patient, the stent was removed a few weeks later due to the persistence of fistula leakage. The use of a 3D-printed personalized airway model allowed for more precise stent customization, optimizing stent fit and allowing for cross-ventilation of branching airways. We determine that an airway model is a beneficial tool for stent optimization but does not prevent the development of some stent-related complications such as airway secretions.

Paclitaxel-eluting silicone airway stent for preventing granulation tissue growth and lung cancer relapse in central airway pathologies

BACKGROUND

Airway stents are used to treat obstructive central airway pathologies including palliation of lung cancer, but face challenges with granulation tissue growth. Paclitaxel is a chemotherapy drug that also suppresses growth of granulation tissue. Yet, side effects arise from administration with toxic solubilizers. By incorporating paclitaxel in silicone stents, delivery of paclitaxel can be localized, and side effects minimized.

METHODS

Paclitaxel was incorporated into Liquid Silicone Rubber (LSR) containing polydimethylsiloxane, either as a powder or solution, prior to curing. Drug release study was compared in vitro at 37°C over 10 days. Drug release was quantified using HPLC, and bronchial cell lines were grown on LSR to investigate drug cytotoxicity, and expression of inflammatory markers, specifically interleukin-6 and interleukin-8.

RESULTS

Release rate of paclitaxel incorporated into silicone rubber was consistent with the Korsmeyer and Weibull models (R² > 0.96). Paclitaxel exposure reduced IL-8 levels in cancer cell lines, whilst no cytotoxic effect was observed in all cell lines at treatment concentration levels (≤ 0.1% (w/v) paclitaxel in silicone).

CONCLUSIONS

Incorporating paclitaxel into a silicone matrix for future use in a tracheobronchial stent was investigated. Drug release from silicone was observed and is a promising avenue for future treatments of central airway pathologies.

Silicone Stent Versus Fully Covered Metallic Stent in Malignant Central Airway Stenosis

BACKGROUND

Airway stenting to restore airway patency in cases of malignant central airway obstruction is an effective palliation treatment. Our goal was to compare the efficacy after deployment and complications of a fully covered self-expandable metal stent (SEMS) (Aerstent) and a silicone stent (Dumon).

METHODS

This was a retrospective cohort of 2 similar groups of patients with malignant central airway obstruction treated with stents between August 2012 and July 2017. Complications were assessed bronchoscopically. A competing risk for death analysis was performed to adjust the probability of developing a complication.

RESULTS

Seventy patients (29 with silicone stents and 41 with SEMS) were included. Stent insertion was successful in all cases. Mucus retention was the most frequent complication (75.9% with silicone stents and 84.8% with SEMS; P = .51), followed by granulation tissue (51.7% with silicone stents and 41.3% with SEMS; P = .52) and migration (6.9% with silicone stents and 13.0% with SEMS; P = .47). In the first month, the cumulative incidence of a complication was 36.7% for silicone stents and 41.3% for SEMS and increased to 90.0% and 97.8% after 6 months, respectively (hazard ratio = 1.66; P = .04). A competing risk for death analysis showed an adjusted hazard ratio of 1.41 (P = .49) indicating no differences in overall complications between stents.

CONCLUSIONS

Both stents were equally successful and safe. The incidence of complications increased over time to 90% at 6 months for both stents. The risk of overall complications was higher for SEMS; nevertheless, when mortality was measured in a competitive risk analysis, no differences were found between SEMS and silicone stents.

Spondylodiscitis and spinal epidural abscess related to long-term placement of an airway stent for malignant central airway obstruction

A 70‐year‐old male was referred to our hospital with lower limb muscle weakness and numbness of the left hand. The patient had previously been diagnosed seven years ago with lung cancer accompanied by central airway obstruction and had received chemoradiotherapy following placement of a metallic stent. Computed tomography (CT) scan revealed an osteolytic lesion which was adjacent to the fractured stent. T2‐weighted magnetic resonance imaging (MRI) demonstrated high signal intensity in the disc space. The patient was diagnosed with spondylodiscitis and spinal epidural abscess related to the airway stent. Despite hemilaminectomy, laminectomy and long‐term antibiotic therapy, the infection was uncontrolled. Moreover, osteolytic destruction and kyphotic deformity progressed. Removal of the airway stent was necessary; however, it was impossible because bronchial resection was required and the risk of mediastinal injury was considered to be high. The patient subsequently received palliative care. Long‐term airway stenting can cause spondylodiscitis and spinal epidural abscess. Indications for the placement of metallic stents for malignant central airway obstruction should be carefully evaluated after considering the difficulty in removal and the long‐term risk of severe complications.

Key points

Significant findings of the study

Long‐term placement and fracture of the airway stent can cause spondylodiscitis and spinal epidural abscess.

What this study adds

The indication of placement of a metallic stent for malignant central airway obstruction should be considered with caution, especially if long‐term survival can be expected.

Clinical Comparison of Airway Stent Placement in Intervention Room and Operating Room

BACKGROUND

Airway stent placement is the effective regimen for central airway obstruction (CAO), while its application scenarios varied. This study aimed to make clinical comparison of airway stent placement in the intervention room and operating room.

METHODS

Patients underwent airway stent placement between 2014 and 2018 were included in this retrospective case-control study. Clinical performance of airway stent placement in intervention room and operating room were compared.

RESULTS

82 patients were included in this study, including 39 in the intervention room and 43 in the operating room. Patients treated in the intervention room had lower Charlson comorbidity index (CCI) (P=0.018) and received less Y-shaped stents (P<0.001). Better clinical response (P=0.026), more stents placed (P<0.001) and longer length of stent (P<0.001) were observed in operating room, while there was no significantly statistical difference of stent-related complications and post-stent survival rate between the two groups. Extracorporeal membrane oxygenation (ECMO) supported airway stent placement procedures were performed in the operating room, which provided definitive safety support for high-risk intervention.

CONCLUSIONS

Patients with CAO could benefit from the operating room scenario, and airway stent placement in the operating room is more suitable for patients with higher CCI scores and receiving more complicated procedures.

Airway stent current practices evaluation: Survey among French bronchoscopy practitioners

BACKGROUND

Airway stenting (AS) is performed for the treatment of benign or malignant central airway stenosis. In France, more than 30 centers practice AS. The aim of this survey was to evaluate the current practice around airway stenting among French bronchoscopy practitioners.

METHOD

We performed an online survey sent to the GELF group (Groupe d'Endoscopie de Langue Française) mailing list. The first part comprised 10 questions about the different attitudes before AS and the second part included 10 questions about the management after AS.

RESULTS

Thirty-six participants answered to the first part of the questionnaire and thirty-three to the second. There were some similarities, for example the absence of prophylactic antibiotic treatment before procedure (86%), use of saline nebulization, and removing or replacing the airway stent in case of persistent chest congestion or infection (73%). We also noted an important heterogeneity of the practices with several differences concerning systematic endoscopic control, bacteriological sampling before procedure (44%) and systematically AS replacement.

CONCLUSION

This survey shows that AS management in France varies between practitioners. Respondents agreed on a few points, but disagreed on several important aspects of the management. These results emphasize the need of expert recommendations to improve AS management.

Safety and Efficacy of the Tracheobronchial Bonastent: A Single-Center Case Series

BACKGROUND

Tracheobronchial stents are widely used devices in interventional pulmonology; however, the current literature on the effectiveness and complication rates of the different types of stents is limited.

OBJECTIVE

We report the largest case series of airway Bonastent placement and describe the efficacy and early (<30 days) and late (≥30 days) complication rates.

METHODS

We performed a retrospective review of our prospectively collected database of patients who underwent therapeutic bronchoscopy with stent placement. All adult patients who had a tracheal/bronchial Bona-stent placed between July 1, 2017, and July 30, 2019, for any indication at our institution were included. The efficacy as well as intraoperative and short- and long-term complications of Bonastent placement were evaluated.

RESULTS

Sixty Bonastents were placed in 50 patients. The etiology was malignant in 90% of the cases, while 2 patients had a tracheoesophageal fistula. All procedures were performed via rigid bronchoscopy. The most common location for stent placement was the bronchus intermedius, followed by the trachea, in 32 and 30% of the cases, respectively. Seventy percent of the patients (35/50) had improvement of respiratory symptoms within 30 days. Twenty-eight stents (48%) were removed at a mean of 74 days. Seventeen patients (34%) died within 30 days of stent placement. The overall complication rate was 54% (27/50 patients) at a mean follow-up of 111 days. The stent-related complication rate was 23.3% (14/60 cases) within <30 days and 53% (18/34 cases) at ≥30 days.

CONCLUSIONS

The tracheobronchial Bonastent is effective for the treatment of patients with central airway obstruction and tracheoesophageal fistulae with an acceptable safety profile.

Retrievable covered metallic segmented Y airway stent for gastrorespiratory fistula of carina or main bronchi

OBJECTIVE

To evaluate the feasibility of new retrievable covered metallic segmented Y airway stents modified with 3-dimensional (3D) printing for gastrorespiratory fistula involving carina or main bronchi.

METHODS

We designed a new retrievable covered metallic segmented Y airway stent to fit the anatomical characteristics of the carina region in individual patients. All stents were individually customized based on a 3D-printed mold. Six patients with gastrorespiratory fistula and aspiration pneumonia after esophagectomy underwent the stent implantation. The stents were retrieved when the fistula was cured or stent-related complications occurred.

RESULTS

Seven Y stents were successfully implanted and removed in 6 patients. All stents expanded well, and the fistulas were completely sealed. Aspiration pneumonia was controlled in 6 patients. The median Karnofsky Performance Status scores significantly improved after stenting compared with those before stent implantation (P = .024). Sputum retention was the most common complication after stenting and was treated with aspiration under bronchoscopy (33.33%). Excessive granulation tissue proliferation was found in 1 patient (16.7%) and was treated with cryotherapy. The indwelling time of the stent was 64 days (interquartile range, 52-69 days). After stent removal, bronchoscopy, gastroscopy, and computed tomography of the chest showed cured fistulas in all patients, and no stents showed fractures.

CONCLUSIONS

Retrievable covered metallic segmented Y airway stents modified with 3D printing appear to be feasible for the treatment of gastrorespiratory fistula involving carina or main bronchi.

State of the Art: Interventional Pulmonology

Interventional pulmonology (IP) has evolved over the past decade from an obscure subspecialty in pulmonary medicine to a recognized discipline offering advanced consultative and procedural services to patients with thoracic malignancy, anatomic airway disease, and pleural disease. Innovative interventions are now also available for diseases not traditionally treated procedurally, such as asthma and emphysema. The IP field has established certification examinations and training standards for IP training programs in an effort to enhance training quality and ensure competency. Validating new technology and proving its cost-effectiveness and effect on patient outcomes present the biggest challenge to IP as the health-care environment marches toward value-based health care. High-quality research is now thriving in IP and promises to elevate its practice into patient-centric evidence-based care.

Comparison of clinical features and stent placement outcomes between airway stenosis caused by primary pulmonary malignancies and that caused by primary non-pulmonary malignancies

Background:

Primary pulmonary malignancies (PPMs) and non-pulmonary malignancies (PNPMs) may result in airway stenosis requiring stenting. This study aimed to compare and evaluate the clinical features and stent placement outcomes of airway stenosis caused by PPMs and PNPMs.

Methods:

A total of 141 patients with malignant airway stenosis who underwent Micro-Tech stent placements between January 2004 and October 2017 at Department of Respiratory Medicine, Beijing Tian Tan Hospital, Capital Medical University were divided into PPM (n = 100) and PNPM groups (n = 41). Patients’ clinical features and stent placement outcomes were collected and analyzed. Chi-square test was used to compare the categorical variables, while independent- or paired-sample t test was used to compare the continuous variables.

Results:

There were no significant differences in age, sex, treatment history, respiratory symptoms, and incidence of obstructive pneumonia between groups. Multiple airway involvement (63.0% vs. 31.7%; χ² = 11.459, P = 0.001) and atelectasis (17.0% vs. 2.4%; χ² = 5.536, P = 0.019) were more common in the PPM group, while extraluminal obstruction (24.4% vs. 6.0%; χ² = 8.033, P = 0.005) was more common in the PNPM group. Before stenting, the American Thoracic Society Dyspnea Index (ADI) and Karnofsky Performance Scale (KPS) scores showed no significant differences between groups (all P > 0.05). After stenting, a satisfactory rate of symptom improvement was achieved in both groups (98.0% and 100.0% in the PPM and PNPM groups, respectively; χ² = 0.016, P = 0.898); ADI and KPS scores, which showed no significant differences between groups (all P > 0.05), were significantly improved in each group (all P < 0.001). Complications after stenting could be effectively managed using bronchoscopic procedures.

Conclusions:

Among cases of malignant airway stenosis requiring stenting, those caused by PPM are more likely to involve multiple airways and are associated with atelectasis, while those caused by PNPM are more likely to cause extraluminal obstruction. Micro-Tech stent placement has the same immediate effect in terms of improvement in respiratory symptoms and performance status for both malignant airway stenosis caused by PPM and that caused by PNPM.

Molecular analysis of the endobronchial stent microbial biofilm reveals bacterial communities that associate with stent material and frequent fungal constituents

Endobronchial stents are increasingly used to treat airway complications in multiple conditions including lung transplantation but little is known about the biofilms that form on these devices. We applied deep sequencing to profile luminal biofilms of 46 endobronchial stents removed from 20 subjects primarily with lung transplantation-associated airway compromise. Microbial communities were analyzed by bacterial 16S rRNA and fungal ITS marker gene sequencing. Corynebacterium was the most common bacterial taxa across biofilm communities. Clustering analysis revealed three bacterial biofilm types: one low diversity and dominated by Corynebacterium; another was polymicrobial and characterized by Staphylococcus; and the third was polymicrobial and associated with Pseudomonas, Streptococcus, and Prevotella. Biofilm type was significantly correlated with stent material: covered metal with the Staphylococcus-type biofilm, silicone with the Corynebacterium-dominated biofilm, and uncovered metal with the polymicrobial biofilm. Subjects with sequential stents had frequent transitions between community types. Fungal analysis found Candida was most prevalent, Aspergillus was common and highly enriched in two of three stents associated with airway anastomotic dehiscence, and fungal taxa not typically considered pathogens were highly enriched in some stents. Thus, molecular analysis revealed a complex and dynamic endobronchial stent biofilm with three bacterial types that associate with stent material, a central role for Corynebacterium, and that both expected and unexpected fungi inhabit this unique niche. The current work provides a foundation for studies to investigate the relationship between stent biofilm composition and clinical outcomes, mechanisms of biofilm establishment, and strategies for improved stent technology and use in airway compromise.

Scarring Airway Stenosis in Chinese Adults: Characteristics and Interventional Bronchoscopy Treatment

Background:

Scarring airway stenosis is commonly seen in China as compared to other developed countries, due to the high prevalence of tuberculosis. Nowadays, interventional bronchoscopy treatment has been widely used to treat this disease in China. This study demonstrated the characteristics of scarring airway stenosis in Chinese adults and retrospectively evaluated the efficacy of interventional bronchoscopy treatment of this disease.

Methods:

Patients with scarring airway stenosis from 18 tertiary hospitals were enrolled between January 2013 and June 2016. The causes, site, and length of scarring airway stenosis were analyzed, and the efficacy of the interventional bronchoscopy treatment was evaluated.

Results:

The final study cohort consisted of 392 patients. Endotracheobronchial tuberculosis (EBTB) was the most common cause of scarring airway stenosis (305/392, 77.8%) in Chinese adults with a high rate of incidence in young women. The left main bronchus was most susceptible to EBTB, and most posttuberculosis airway scarring stenosis length was 1.1–2.0 cm. The average clinical success rate of interventional bronchoscopy treatment for scarring airway stenosis in Chinese patients is 60.5%. The stent was inserted in 8.7% scarring airway stenosis in China.

Conclusions:

Scarring airway stenosis exhibits specific characteristics in Chinese patients. Interventional bronchoscopy is a useful and safe treatment method for the disease.

A Pilot Study of a Novel through-the-Scope Self-Expandable Metallic Airway Stents Delivery System in Malignant Central Airway Obstruction

Objective

Self-expandable metallic (SEM) airway stents are an important approach to malignant central airway obstruction (CAO). SEM airway stent insertions are usually performed under fluoroscopic guidance over a guide wire placed through a flexible bronchoscope often resulting in a longer procedure time and exposure to radiation. In this pilot study, we designed a novel delivery system of the through-the-scope (TTS) SEM airway stent insertion and observed its feasibility.

Methods

From Jan 2015 to Sept 2016, 25 consecutive patients with inoperable malignant CAO were enrolled requiring airway stent implantation. All patients were followed up to death or at least 6 months.

Results

36 TTS stents were inserted into 25 patients using a flexible bronchoscope under general anesthesia or local anesthesia. All stents were successfully deployed directly through the working channel (2.8 mm diameter) of the flexible bronchoscope in 91.7% (33/36) of the subjects. The mMRC score and stenosis grade improved significantly after stent implantation. The common stent-related complications were secretion retention (25%, 9/36), development of granulation tissue (13.9%, 5/36), tumor in-growth (13.9%, 5/36), and hemoptysis (8.3%, 3/36). The 6-month overall survival (OS) was 44% (11/25).

Conclusion

The novel TTS stent release system was an effective and safe approach in malignant central airway obstruction.

Comparison of Covered Laser-cut and Braided Respiratory Stents: From Bench to Pre-Clinical Testing

Lung cancer patients often suffer from severe airway stenosis, the symptoms of which can be relieved by the implantation of stents. Different respiratory stents are commercially available, but the impact of their mechanical performance on tissue responses is not well understood. Two novel laser-cut and hand-braided nitinol stents, partially covered with polycarbonate urethane, were bench tested and implanted in Rhön sheep for 6 weeks. Bench testing highlighted differences in mechanical behavior: the laser-cut stent showed little foreshortening when crimped to a target diameter of 7.5 mm, whereas the braided stent elongated by more than 50%. Testing also revealed that the laser-cut stent generally exerted higher radial resistive and chronic outward forces than the braided stent, but the latter produced significantly higher radial resistive forces at diameters below 9 mm. No migration was observed for either stent type in vivo. In terms of granulation, most stents exerted a low to medium tissue response with only minimal formation of granulation tissue. We have developed a mechanical and in vivo framework to compare the behavior of different stent designs in a large animal model, providing data, which may be employed to improve current stent designs and to achieve better treatment options for lung cancer patients.

A Design-Based Stereologic Method to Quantify the Tissue Changes Associated with a Novel Drug-Eluting Tracheobronchial Stent

BACKGROUND

Granulation tissue is a common complication of airway stenting, but no published methods can quantify the volume and type of tissue that develops.

OBJECTIVE

To use design-based stereology to quantify changes in tissue volume and type associated with airway stenting.

METHODS

We compared drug-eluting stents (DES) filled with gendine to standard silicone stents in pigs in an assessor-blinded randomized trial. Tracheal stents were placed via rigid bronchoscopy. After 1 month, animals were euthanized and necropsies were performed. Antimicrobial effects of the DES were assessed in trachea tissue samples, on the DES surface, and with residual gel from the DES reservoir. Tracheal thickness was measured using orthogonal intercepts. Design-based stereology was used to quantify the volume density of tissues using a point-counting method. The volume of each tissue was normalized to cartilage volume, which is unaffected by stenting.

RESULTS

Pigs were randomized to DES (n = 36) or control stents (n = 9). The drug was successfully eluted from the DES, and the stent surface showed antibacterial activity. DES and controls did not differ in tissue microbiology, tracheal thickness, or granulation tissue volume. Compared to nonstented controls, stented airways demonstrated a 110% increase in soft-tissue volume (p = 0.005). Submucosal connective tissue (118%; p < 0.0001), epithelium (70%; p < 0.0001), submucosal glands (47%; p = 0.001), and smooth muscle (41%; p < 0.0001) increased in volume.

CONCLUSION

Stenting doubles the volume of soft tissue in the trachea. Design-based stereology can quantify the tissue changes associated with airway stenting.

3D printing for airway disease

It has been 30 years since the first commercial three-dimensional (3D) printer was available on market. The technological advancement of 3D printing has far exceeded its implementation in medicine. The application of 3D printing technology has the potential of playing a major role within interventional pulmonology; specifically, in the management of complex airway disease. Tailoring management to the patient-specific anatomical malformation caused by benign or malignant disease is a major challenge faced by interventional pulmonologists. Such cases often require adjunctive therapeutic procedures with thermal therapies followed by dilation and airway stenting to maintain the patency of the airway. Airway-stent size matching is one key to reducing stent-related complications. A major barrier to matching is the expansion of the stent in two dimensions (fixed sizes in length and diameter) within the deformed airway. Additional challenges are created by the subjective oversizing of the stent to reduce the likelihood of migration. Improper sizing adversely affects the stability of the stent. The stent-airway mismatch can be complicated by airway erosion, perforation, or the formation of granulation tissue. Stents can migrate, fracture, obstruct, or become infected. The use of patient-specific 3D printed airway stents may be able to reduce the stent airway mismatch. These stents allow more precise stent-airway sizing and minimizes high-pressure points on distorted airway anatomy. In theory, this should reduce the incidence of the well-known complications of factory manufactured stents. In this article, the authors present the brief history of 3D printed stents, their consideration in select patients, processing steps for development, and future direction.

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.

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.

Interventional bronchoscopy in adults

INTRODUCTION

The field of interventional pulmonology (IP) is a rapidly maturing subspecialty of pulmonary medicine, which emphasizes advanced diagnostic and therapeutic bronchoscopy for the evaluation and management of central airway obstruction, mediastinal/hilar adenopathy and lung nodules/masses, as well as minimally invasive diagnostic and therapeutic pleural procedures. Areas covered: This review describes advances in diagnostic and therapeutic bronchoscopic techniques. Expert commentary: In the past decade, there has been a remarkable growth in available technology and equipment, as well as clinical and translational research efforts focused on patient-centered outcomes. Furthermore, the recent establishment of a uniform accreditation standard for all IP fellowship programs in the United States was an important step in the continued evolution of this subspecialty of pulmonary medicine.

Successful Treatment of Life-threatening Tracheal Stenosis Caused by Malignancy with a Self-expanding Hybrid Stent

Tracheal stenosis caused by malignancy is a life-threatening complication. We performed stent therapy in two patients using the AERO™ stent, launched in late 2016 in Japan. One patient presented with stenosis of the trachea due to adenoid cystic carcinoma and the other with stenosis of the trachea due to esophageal cancer. Both patients showed improved symptoms, and no complications were identified. This is the first report of a favorable outcome with the use of this hybrid stent in Japan, and the findings suggest that insertion of the AERO hybrid stent is an effective way to improve patients' quality of life.

Evaluating the interaction of a tracheobronchial stent in an ovine in-vivo model

Tracheobronchial stents are used to restore patency to stenosed airways. However, these devices are associated with many complications such as stent migration, granulation tissue formation, mucous plugging and stent strut fracture. Of these, granulation tissue formation is the complication that most frequently requires costly secondary interventions. In this study a biomechanical lung modelling framework recently developed by the authors to capture the lung in-vivo stress state under physiological loading is employed in conjunction with ovine pre-clinical stenting results and device experimental data to evaluate the effect of stent interaction on granulation tissue formation. Stenting is simulated using a validated model of a prototype covered laser-cut tracheobronchial stent in a semi-specific biomechanical lung model, and physiological loading is performed. Two computational methods are then used to predict possible granulation tissue formation: the standard method which utilises the increase in maximum principal stress change, and a newly proposed method which compares the change in contact pressure over a respiratory cycle. These computational predictions of granulation tissue formation are then compared to pre-clinical stenting observations after a 6-week implantation period. Experimental results of the pre-clinical stent implantation showed signs of granulation tissue formation both proximally and distally, with a greater proximal reaction. The standard method failed to show a correlation with the experimental results. However, the contact change method showed an apparent correlation with granulation tissue formation. These results suggest that this new method could be used as a tool to improve future device designs.