Biodegradable polydioxanone stents in the treatment of adult patients with tracheal narrowing

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).

Lung transplant airway complications treated with biodegradable airway stents: The Dutch multi-center experience

INTRODUCTION

Treatment of post lung-transplant airway complications is challenging, and treatment with conventional airway stents is associated with adverse events. More recently, biodegradable airway stents (BDS) have been introduced and may be used to reduce these adverse events. In this study we explore the feasibility of treatment with BDS post lung transplant.

METHODS

All patients treated with BDS in The Netherlands were included in this retrospective multicenter study. Feasibility, life span of the stent, occurrence of adverse events, and evolution of lung function were evaluated.

RESULTS

Twelve patients (six malacia and six stenosis) received a total of 57 BDS, ranging from 1 to 10 BDS per patient. Six patients had been pretreated with conventional airway stents. Median stent life span was 112 days (range 66-202). No adverse events occurred during stent placement. In 5 out of 57 stent placements, a single additional bronchoscopy was necessary because of mucus accumulation (n = 4) or excessive granulation tissue (n = 1). All stent naïve patients became airway stent independent after treatment; all patients pretreated with conventional airway stents were still airway stent dependent at the end of follow up.

CONCLUSION

Treatment with BDS is safe and feasible. Adverse events were mild and easily treatable. All patients with initial treatment with BDS were airway stent independent at the end of follow up with a median treatment of 4 BDS.

Tracheobronchial stents: an expanding prospect

The first dedicated tracheobronchial silicone stent was designed by the French pulmonologist Jean-Paul Dumon. The most common indications for stenting are to minimise extrinsic airway compression from mass effect, maintain airway patency due to intrinsic obstruction or treat significant nonmalignant airway narrowing or fistulae. Silicone stents require rigid bronchoscopy for insertion; however, they are more readily repositioned and removed compared with metallic stents. Metallic stents demonstrate luminal narrowing when loads are applied to their ends, therefore stents should either be reinforced at the ends or exceed the area of stenosis by a minimum of 5 mm. Nitinol, a nickel-titanium metal alloy, is currently the preferred material used for airway stents. Airway stenting provides effective palliation for patients with severe symptomatic obstruction. Drug-eluting and three-dimensional printing of airway stents present promising solutions to the challenges of the physical and anatomical constraints of the tracheobronchial tree. Biodegradable stents could also be a solution for the treatment of nonmalignant airway obstruction.

Three Decades Single Center Experience of Airway Complications After Lung Transplantation

Post lung transplantation airway complications like necrosis, stenosis, malacia and dehiscence cause significant morbidity, and are most likely caused by post-operative hypo perfusion of the anastomosis. Treatment can be challenging, and airway stent placement can be necessary in severe cases. Risk factors for development of airway complications vary between studies. In this single center retrospective cohort study, all lung transplant recipients between November 1990 and September 2020 were analyzed and clinically relevant airway complications of the anastomosis or distal airways were identified and scored according to the ISHLT grading system. We studied potential risk factors for development of airway complications and evaluated the impact on survival. The treatment modalities were described. In 651 patients with 1,191 airway anastomoses, 63 patients developed 76 clinically relevant airway complications of the airway anastomoses or distal airways leading to an incidence of 6.4% of all anastomoses, mainly consisting of airway stenosis (67%). Development of airway complications significantly affects median survival in post lung transplant patients compared to patients without airway complication (101 months versus 136 months, p = 0.044). No significant risk factors for development of airway complication could be identified. Previously described risk factors could not be confirmed. Airway stents were required in 55% of the affected patients. Median survival is impaired by airway complications after lung transplantation. In our cohort, no significant risk factors for the development of airway complications could be identified.

[Interventionnal bronchoscopy for the treatment of tracheobronchomalacia]

Tracheobronchomalacia is usually characterized by more than 50% expiratory narrowing in diameter of the trachea and the bronchi. The expiratory collapse includes two entities: (1) the TBM related to the weakness of the cartilaginous rings, and (2) the Excessive Dynamic Airway Collapse (EDAC) due to the excessive bulging of the posterior membrane. Patients have nonspecific respiratory symptoms like dyspnea and cough. Diagnosis is confirmed by dynamic tests: flexible bronchoscopy and/or computed tomographic scan of the chest. There are different forms of tracheobronchomalacia in adults: primary (genetic, idiopathic) or secondary to trauma, tracheotomy, intubation, surgery, transplantation, emphysema, infection, inflammation, chronic bronchitis, extrinsic compression; or undiagnosed in childhood vascular rings. Some management algorithms have been proposed, but no specific recommendation was established. Only symptomatic patients should be treated. Medical treatments and noninvasive positive pressure ventilation should be the first line therapy, after evaluation of various quality measures (functional status, performance status, dyspnea and quality of life scores). If symptoms persist, therapeutic bronchoscopy permits: (1) patient's selection by stent trial to determine whether patient benefit for surgical airway stabilization; (2) malacic airways stenting in patients who are not surgical candidates, improving QOL despite a high complication rate; (3) the management of stent-related complication (obstruction, plugging, migration granuloma); (4) alternative therapeutics like thermo-ablative solution. Lasty, the development of new types of stents would reduce the complication rates. These different options remained discussed.

Bio-characteristics and Efficacy Analysis of Biodegradable Poly Dioxanone Dermal Filler in a Mouse Model and Humans

BACKGROUND/AIM

This research investigated the biophysical properties, safety, and efficacy of polydioxanone (PDO) filler compared to poly-L-lactic acid (PLLA), polycaprolactone (PCL), and hyaluronic acid (HA) fillers. In both mouse and human skin models, a novel collagen stimulation was compared with hyaluronic acid filler.

MATERIALS AND METHODS

An electron microscope was used to capture images of the solid particle microsphere shape. Moreover, animal models named SKH1-Hrhr were used to assess the 12-week persistence of PDO, PLLA, or PCL filler. H&E and Sirus Red staining were used to compare collagen density. Five participants in the clinical trial received three injections in the dermis over an eight-month period. Skin density, wrinkles, and gloss were evaluated using DUB® skin scanner, Antera 3D CS, Mark-Vu, and Skin gloss meter after injection to assess the efficacy of fillers.

RESULTS

PDO microspheres had uneven surfaces and were spherical and consistent in size. In comparison to other fillers, the PDO filler demonstrated complete biodegradability in just 12 weeks and better neocollagenesis, and a lower inflammatory response than the HA filler. After three injections, the human body assay showed a significant improvement in skin gloss, wrinkles, and density.

CONCLUSION

In comparison to PCL and PLLA, PDO filler demonstrated a comparable volume increase rate and better biodegradability. Furthermore, although its physical characteristics are similar to those of a solid, PDO has the advantage of being more organically spread. In photoaging mice, PDO fillers are thought to offer equivalent or superior anti-wrinkle and anti-aging effects to PBS, PCL, and PLLA.

Utility and safety of airway stenting in airway stenosis after lung transplant: A systematic review

Background

Airway complications seriously affect the clinical outcomes and long-term prognosis of lung-transplantation patients. Airway stenting provides effective palliation for patients with airway stenosis. However, a lack of consensus regarding the efficacy and safety of airway stents in airway stenosis after lung transplantation. This study critically evaluated all available evidence regarding this concern.

Methods

We retrieved studies from EMBASE, PubMed, and Cochrane Library databases. Studies were included if they reported baseline characteristics of airway complications after lung transplantation, stenting for airway stenosis, or prognosis.

Results

In total, 279 papers were screened and 17 papers were included in final analysis. The short-term efficacy of airway stenting was assessed in almost all studies, with immediate palliation in symptom and improved pulmonary function reported. Eleven of the included studies evaluated the long-term efficacy of stent therapy, with no distinct lung function. The median overall survival time was 1,124 (95% confidence interval 415–1,833) days in stented patients only. Stent-related complications are common regardless of the material; However, serious complications are rare and can be improved with routine management.

Conclusion

We demonstrated that airway stenting is a safe and effective method to treat airway stenosis after lung transplantation. The short-term effect was significant, while the long-term efficacy on survival rate needed further investigations.

Systematic review registration

www.crd.york.ac.uk/prospero/, identifier: CRD42022364427.

Bioresorbable PPDO sliding-lock stents with optimized FDM parameters for congenital heart disease treatment

Stent implantation has been a promising therapy for congenital heart disease (CHD) due to better efficacy. Compared to permanent metal stents, bioresorbable polymer stents have shown a great advantage in accommodating the vascular growth of pediatric patients, but the application is still limited due to inferior radial strength. Here, bioresorbable poly(p-dioxanone) (PPDO) sliding-lock stents for CHD treatment were fabricated by fused deposition modeling (FDM). The effects of FDM processing parameters, including nozzle temperature, bed temperature, layer thickness, and printing speed, on the mechanical properties of PPDO parts were investigated to optimize the processing condition to enhance the radial strength of stents. Finite element analysis (FEA) was also used to evaluate the mechanical properties of stents. PPDO sliding-lock stents fabricated under optimized FDM parameters showed radial strength of 3.315 ± 0.590 N/mm, superior to benchmark commercial metal stents. Radial strength curve and compression behavior of PPDO sliding-lock stents were investigated. Results of FEA exhibited that strut width, shape of the mesh cell and surface coverage ratio had an impact on the compression force of PPDO sliding-lock stents. PPDO sliding-lock stents fabricated with optimized FDM parameters show favorable mechanical performance and meet the requirement of CHD treatment.

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.

A Complex In Vitro Degradation Study on Polydioxanone Biliary Stents during a Clinically Relevant Period with the Focus on Raman Spectroscopy Validation

Biodegradable biliary stents are promising treatments for biliary benign stenoses. One of the materials considered for their production is polydioxanone (PPDX), which could exhibit a suitable degradation time for use in biodegradable stents. Proper material degradation characteristics, such as sufficient stiffness and disintegration resistance maintained for a clinically relevant period, are necessary to ensure stent safety and efficacy. The hydrolytic degradation of commercially available polydioxanone biliary stents (ELLA-CS, Hradec Králové, Czech Republic) in phosphate-buffered saline (PBS) was studied. During 9 weeks of degradation, structural, physical, and surface changes were monitored using Raman spectroscopy, differential scanning calorimetry, scanning electron microscopy, and tensile and torsion tests. It was found that the changes in mechanical properties are related to the increase in the ratio of amorphous to crystalline phase, the so-called amorphicity. Monitoring the amorphicity using Raman spectroscopy has proven to be an appropriate method to assess polydioxanone biliary stent degradation. At the 1732 cm⁻¹ Raman peak, the normalized shoulder area is less than 9 cm⁻¹ which indicates stent disintegration. The stent disintegration started after 9 weeks of degradation in PBS, which agrees with previous in vitro studies on polydioxanone materials as well as with in vivo studies on polydioxanone biliary stents.

State of the Science in Tracheal Stents: A Scoping Review

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Endoscopically Applied Biodegradable Stent in a Rabbit Model of Pediatric Tracheomalacia

OBJECTIVES

A polydioxanone (PDO) stent was developed to treat tracheomalacia in pediatric patients. However, its safety and efficacy need to be verified in animal studies before clinical trials in patients can be conducted. This study evaluated the safety and efficacy of a PDO stent in normal and tracheomalacia-model rabbits.

METHODS

In total, 29 New Zealand white rabbits were used: 13 for evaluating the biocompatibility of the PDO stent in normal rabbits and 16 for the creation of a tracheomalacia model. The tracheomalacia model was successfully established in 12 rabbits, and PDO stents were placed in eight of those rabbits.

RESULTS

The PDO stent was successfully positioned in the trachea of the normal rabbits using an endoscopic approach, and its degradation was observed 10 weeks later. The stent fragments did not induce distal airway obstruction or damage, and the mucosal changes that occurred after stent placement were reversed after degradation. The same procedure was performed on the tracheomalacia-model rabbits. The survival duration of the tracheomalacia rabbits with and without stents was 49.0±6.8 and 1.0±0.8 days, respectively. Thus, the PDO stent yielded a significant survival gain (P=0.001). In the tracheomalacia rabbits, stent degradation and granulation tissue were observed 7 weeks after placement, leading to airway collapse and death.

CONCLUSION

We successfully developed a PDO stent and an endoscopic guide placement system. The degradation time of the stent was around 10 weeks in normal rabbits, and its degradation was accelerated in the tracheomalacia model. The mucosal changes associated with PDO stent placement were reversible. Placement of the PDO stent prolonged survival in tracheomalacia-model rabbits.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Investigation of Migration-Preventing Tracheal Stent with High Dose of 5-Fluorouracil or Paclitaxel for Local Drug Delivery

Stent migration is one of the common reasons for the failure of tracheal stent. An antitumor drug/tracheal stent combination can promptly relieve dyspnea caused by tracheal stenosis and locally treat malignant occupying lesion or tumor. To prevent stent migration for more effective treatment, we prepared a migration-preventing nitinol tracheal stent (TS) with a high dose of 5-fluorouracil or paclitaxel (5-FU/TS or PTX/TS) by stent surface coating with a bilayered film, which is composed of a drug-loaded layer containing Carbopol 974P as mucoadhesive matrix and a blank Carbopol 974P layer. The resulting stent had a similar mechanical performance with the nitinol tracheal stent itself. The bilayered film containing 30% PTX (PTX30) could keep adhesion to porcine mucosa for 221.7 ± 11.4 min in PBS at a stirring speed of 150 rpm, and the corresponding PTX30/TS was difficult to be moved in the porcine tracheal lumen with a pulling force less than 0.7 N, indicating its good migration-preventing ability. The migration-preventing ability of the 5-FU/TS or PTX/TS was related to the compositions of bilayered films. The 5-FU release from the 5-FU/TS was dominated by a relaxation mechanism, while the PTX release was mainly controlled by a diffusion mechanism. Moreover, the 5-FU permeation from the 5-FU loaded film through the porcine tracheal mucosa was determined by the 5-FU dissolution, and PTX permeation was limited by the trans-mucosa process. After the deployment of PTX30/TS, inflammatory responses were observed in the rabbit tracheas and gradually alleviated during the follow-up period.

Biodegradable polydioxanone stent as a new treatment strategy for tracheal stenosis in a rabbit model

PURPOSE

Congenital tracheal stenosis (CTS) is a rare condition and difficult to treat. Slide tracheoplasty has unsatisfactory outcomes for severe neonatal symptomatic CTS. This study evaluated the use of biodegradable polydioxanone stents (BD stent) in a rabbit model of CTS.

METHODS

Tracheal stenosis was induced in female Japanese white rabbits, 9-10weeks old, by direct scraping of the tracheal mucosa with a nylon brush following transverse incision of the trachea (control group, n=4). Seven days later, we incised the trachea again and inserted a BD stent (15×5mm) into the trachea (stent group, n=4). Arterial blood gas analysis was performed twice weekly for 1month after the procedure.

RESULTS

In the control group, respiratory acidosis arising from ventilatory failure was observed on postoperative days 7-10. Rabbits were sacrificed at 11.5days after scraping. Severe tracheal stenosis resulting from inflammatory granulation was detected in the scraped region in all rabbits. In the stent group, arterial blood gas analysis was normal at 28days after stent insertion. The BD stent maintained patency of the tracheal lumen and prolonged survival for 1month.

CONCLUSIONS

The use of BD stent represents a promising new treatment method for tracheal stenosis.