Use of a biodegradable, oversized stent in a child with tracheomalacia secondary to vascular external compression

Biodegradable tracheal stents: our ten-year experience with adult patients

BACKGROUND

Biodegradable (BD) stents made from polydioxanone have been used only in human airways. These stents combine the advantages of classical tracheal stents, and fewer side effects are expected due to their biocompatibility and their time-limited presence in airways. However, new clinical consequences have arisen. Here, the authors share their experiences with BD stents for tracheal indications, focusing on their safety and efficacy.

METHODS

This was a retrospective review of a collected database of adult patients who underwent implantation of biodegradable tracheal stents between September 2013 and December 2022 at the Department of Respiratory Medicine of the 1st Faculty of Medicine in Prague and Thomayer University Hospital. The indications included functionally significant nonmalignant tracheal stenosis and tracheomalacia. Self-expandable, biodegradable, polydioxanone tracheal stents manufactured by ELLA-CS Ltd. (Hradec Kralove, Czech Republic) were implanted during rigid bronchoscopy under general anaesthesia. All patients were followed up in the department and were provided with the necessary care. The main efficacy and safety parameters and relationships were analysed using descriptive statistics and Fisher´s exact, Wilcoxon and Kruskal‒Wallis tests.

RESULTS

A total of 65 stents were implanted in 47 adult patients. During the first two months after implantation, when adequate function was expected, the stent was found to be effective in 26 out of 39 patients who completed this period (66.7%). The clinical effectiveness reached 89.7%, as early restenoses were mostly mild and necessitated treatment in only 4 patients. The frequencies of significant mucostasis, migration and granulation tissue growth were 2.6%, 7.5% and 23.1%, respectively, during this period. Thirty-four participants completed the half-year follow-up period after the first or second stent insertion, and some were followed up beyond this period. Poor control of symptoms, the development of restenosis and the need for interventions were characteristic of this period as the stents degraded. Twenty-two patients who experienced remodelling or stabilization of the tracheal lumen achieved a stent-free state. Seven patients underwent subsequent surgical treatment.

CONCLUSIONS

BD stents are safe and provide adequate tracheal support until they begin to degrade. The use of BD stents necessitates close monitoring of patients and accurate treatment of possible restenosis.

TRIAL REGISTRATION

Based on project NT14146 - Biodegradable stents in the management of the large airways (2013-2015, MZ0/NT), registered on May 1, 2013, in the Research and Development and Innovation Information System of the Czech Republic and at ClinicalTrials.gov (reg. no. NCT02620319, December 2, 2015).

Nonmalignant Central Airway Obstruction: Options for Challenging Cases

Benign central airway obstruction is commonly referred as nonmalignant central airway obstruction (NMCAO). This is in part related to its lack of benign nature and significant life-quality impairment in patients. It is a pathologic entity with various etiologies and therefore a wide range of therapeutic options are available. Evidence regarding the optimal management that could provide a sustained restoration of airway patency is lacking. The lack of a common pathophysiologic pathway translating into a nonspecific symptom presenting as NMCAO has complicated treatment standardization and subsequently limited solid research to favor of one approach over another one. Our intent is to describe the limited evidence of the most utilized nonsurgical treatment for NMCAO as well as some upcoming promising therapeutic options such as mitomycin C injection, microdebrider, biodegradable stents, radiotherapy, Hybrid Knife, and endoluminal spray cryotherapy. Our goal with this manuscript is to motivate other authors to venture into prospective, multicenter, open-label trials aimed to describe long-term outcomes in patients with NMCAO.

Resorbable airway splint, stents, and 3D reconstruction and printing of the airway in tracheobronchomalacia

Tracheobronchomalacia (TBM) is the most common tracheobronchial obstruction. Most cases are mild to moderate; therefore, they do not need surgical treatment. Severe tracheomalacia, however, represents a diagnostic and therapeutic challenge since they are very heterogeneous. In the armamentarium of resources for the treatment of dynamic airway collapse, splints and stents are two underused strategies and yet, they may represent the best alternative in selected cases. Lately, computed tomography 3D reconstruction of the airway has been used for the design of virtual models that can be 3D-printed for the creation of novel devices to address training, simulation, and biotechnological implants for refractory and severe airway malformations. This manuscript examines the role of resorbable stents, splints, and the 3D reconstruction and printing of the pediatric airway in tracheobronchomalacia.

In-vivo efficacy of biodegradable ultrahigh ductility Mg-Li-Zn alloy tracheal stents for pediatric airway obstruction

Pediatric laryngotracheal stenosis is a complex congenital or acquired airway injury that may manifest into a potentially life-threatening airway emergency condition. Depending on the severity of obstruction, treatment often requires a combination of endoscopic techniques, open surgical repair, intraluminal stenting, or tracheostomy. A balloon expandable biodegradable airway stent maintaining patency while safely degrading over time may address the complications and morbidity issues of existing treatments providing a less invasive and more effective management technique. Previous studies have focused on implementation of degradable polymeric scaffolds associated with potentially life-threatening pitfalls. The feasibility of an ultra-high ductility magnesium-alloy based biodegradable airway stents was demonstrated for the first time. The stents were highly corrosion resistant under in vitro flow environments, while safely degrading in vivo without affecting growth of the rabbit airway. The metallic matrix and degradation products were well tolerated by the airway tissue without exhibiting any noticeable local or systemic toxicity.

The role of bioresorbable intraluminal airway stents in pediatric tracheobronchial obstruction: A systematic review

INTRODUCTION

Tracheal stenosis and tracheobronchomalacia are complicated, patient-specific diseases that can be treated with intraluminal stenting. Most commonly, silicone and metal stents are utilized, however, they pose significant early and late morbidity and are further complicated by growth of the airway in the pediatric population. Given recent improvements in materials science, there is a growing body of evidence suggesting a strong role for bioresorbable intraluminal stents in treating pediatric tracheobronchial obstruction.

METHODS

A PubMed.gov literature search was performed on December 3, 2019 and May 15, 2020, and a 2-researcher systematic review was performed following the PRISMA criteria. The following search query was utilized: (((((((bioresorbable) OR bioabsorbable) OR resorbable) OR absorbable) OR biodegradable AND airway) OR trachea) AND stent. A pooled statistical analysis was performed on all reported pediatric patients using SPSS software.

RESULTS

1369 publications were screened and 26 articles with original data were identified. Materials used included polydioxanone (PDO), poly-l-lactic acid (PLLA), polyglycolic acid/poly-l-lactide co-polymer with Proglactin 910 (Vicryl®-PDS®), polycaprolactone (PCL), magnesium alloys, and co-polymers in varying proportions. Twelve articles presented data on human subjects, 8 of which were case series and case reports on pediatric populations using polydioxanone (PDO) stents. Pooled statistical analysis demonstrated an average age of 19 months (range 0.25-144), 56.5% associated with a cardiovascular anomaly, and overall complication rate of 21.7%, with a stent fragment foreign body being the most common (8.7%), followed by significant granulation tissue (4.3%), stent migration (4.3%), and local stenosis (4.3%). Comparative analysis demonstrated short-term improvement (up to 1 month) has a statistically significant association with tracheobronchomalacia versus tracheal stenosis on chi-squared test (p = 0.001). The remaining analyses did not yield statistical significance.

CONCLUSION

The reported application of bioresorbable materials as intraluminal airway stents is positive. All comparative animal studies report biocompatibility and fewer morbidities compared to metal and silicone stents, however, in human studies there are concerns over the short interval of degradation and the potential for obstructive foreign bodies in poorly seated stents. Overall, there are clear, reproducible advantages to bioresorbable intraluminal stents in pediatric airway obstruction, as well as common pitfalls, that warrant further research.

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.