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.
CONCLUSIONS: 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.

UNASSIGNED: Benign airway stenosis (BAS), namely airway narrowing caused by a variety of benign lesions, can lead to varying degrees of breathing difficulties and even death due to asphyxia. This study aimed to elucidate the clinical characteristics of BAS, including etiology, treatment and pathology, by analyzing the clinical data of BAS patients.
UNASSIGNED: A retrospective analysis was conducted using the clinical data of 617 BAS cases from January 2017 to December 2022. The pathological characteristics of the tissues were assessed by hematoxylin-eosin (H&E) and Masson\'s staining. Besides, protein expression levels were determined by immunohistochemistry (IHC).
UNASSIGNED: A total of 617 patients were included (333 females [53.97%] and 284 males [46.03%]), with an average age of 48.93 ± 18.30 (range 14-87). Tuberculosis (n = 306, 49.59%) and trauma (n = 179, 29.02%) were the two leading etiologies of BAS, followed by airway foreign bodies (FB, n = 74, 11.99%), external compression (n = 25, 4.05%) and other etiologies (n = 33, 5.35%). Among 306 tuberculous tracheobronchial stenosis (TBTS) cases, most were females (n = 215, 70.26%), and TBTS mainly occurred in the left main bronchus (n = 97, 31.70%), followed by the right middle bronchus (n = 70 cases, 22.88%). The majority of TBTS patients (n = 259, 84.64%) were treated by interventional therapy. The condition of 179 BAS patients was ascribed to trauma, such as tracheal intubation (n = 92, 51.40%), tracheotomy (n = 69, 38.56%), injury (n = 15, 8.38%) and surgery (n = 3, 1.68%), which mostly took place in the trachea (n = 173, 96.65%). TAS patients mainly received interventional therapy (n = 168, 93.85%) and stent implantation (n = 47, 26.26%). The granulation tissues of BAS primarily featured inflammation, proliferation and fibrosis. IHC indicated the up-regulated expressions of transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (α-SMA), collagen type I protein (COL-I) and vimentin, and the down-regulated expression of E-cadherin, which indicated fibrosis and epithelial-mesenchymal transition (EMT).
UNASSIGNED: Tuberculosis was the main etiology, and trauma was the secondary etiology. The granulation tissues of BAS were characterized by inflammation, fibrosis and probably EMT. Comprehensive interventional therapy is an effective method of treating BAS.

The long-term efficacy of the Dumon stent in the treatment of benign airway stenosis is unclear.
The objective of this study was to evaluate the long-term efficacy and safety of the Dumon stent in patients with benign airway stenosis.
We retrospectively reviewed patients with benign airway stenosis who were treated with a Dumon stent at the First Affiliated Hospital of Guangzhou Medical University between March 2014 and October 2021. We included patients with successful removal of silicone stents after implantation. The clinical data and information on bronchoscopic interventional procedures and related complications were collected and analyzed.
Ninety-nine patients with benign airway stenosis were included. The stent was placed mainly in the trachea (44.4%) and left main bronchus (43.4%). The main type of stenosis was post-tuberculosis bronchial stenosis (57.6%). The overall cure rate was 60.6%. Stent-related complications included retention of secretions (70.7%), granuloma formation (67.7%), stent angulation (21.2%), and stent migration (12.1%). The stent was less effective for left main bronchus stenosis (p = 0.012). Multivariate logistic regression analysis identified that stent placement for more than 13 months, a stent-intervention number of ⩽ 1 predicted a favorable outcome.
The efficacy and safety of the Dumon stent for benign airway stenosis need improvement. The stent is less effective for left main bronchus stenosis; regular follow-up is required in such cases. Stent placement for > 13 months and no more than once stent intervention within a 6-month period were associated with a favorable outcome.

Benign airway stenosis is a severe disease that can result in death with improper treatment. Clinicians must know about airway stents to choose the best one in their daily practice.
PubMed, Embase, and other electronic databases and websites were searched to identify relevant randomized controlled trials and meta-analyses. This review summarizes different types of airway stents and analyzes their advantages and disadvantages.
Increasing attention has been given to the indications and prognosis of benign airway stenosis treated with different airway stents. With more investigations and data, better alternatives to silicone stents could be developed in the future.

OBJECTIVE: Cuffed endotracheal intubation and stent implantation were employed to simulate two types of benign airway stenosis and further to analysis the different features between them from trachecscopic characteristics, gross anatomy to histopathological changes. In addition, our study explored the therapeutic effect of mitomycin C at different concentrations on granulation tissue caused by stent implantation in order to provide a new therapeutic strategy for clinical treatment of benign airway stenosis.
METHODS: Twelve beagle dogs were randomly divided into four groups, with three dogs in each group. Group A: Three beagle dogs were intubated through oral trachea after general anesthesia and cuff pressure maintained at 200 mmHg for 24 h. Group B, Group C and Group D: endotracheal coated self-expanding metal stents were placed after general anesthesia under the guidance of bronchoscope. On the Day7 after stent implantation, Group B, as control group, was injected phosphate buffer solution of 1 ml into granulation tissue at the end of stent; Group C was injected mitomycin C of 1 ml at 0.4 mg/ml and Group D was injected mitomycin C of 1 ml at 0.8 mg/ml into granulation tissue at the end of metal airway stent respectively, the same method as Group B. Bronchoscopy was used to observe tracheal lumen on the seventh day, fourteenth day and twenty-first day after modeling and pathological changes were examined on twenty-first day.
RESULTS: Two models of benign airway stenosis can be established by cuffed endotracheal intubation and stent implantation. There was tracheal rupture in the trachea cartiage ring in the cuffed endotracheal intubation group, but was\'t in stent implantation group. Histopathological characteristics were different between cuffed endotracheal intubation and stent implantation groups. In stent placement groups, we found that the stenosis degree of mitomycin C at 0.4 mg/ml was approximately 19%-32%, mitomycin C at 0.8 mg/ml was approximately 16%-21% and the control group was approximately 36%-47%.
CONCLUSIONS: The two models of canine benign tracheal stenosis induced by cuffed endotracheal intubation and stent implantation are relatively simple, reliable and reproducible and have different characteristics. Mitomycin C could inhibit proliferation of granulation tissue and attenuate the degree of airway stenosis caused by stent implantation.

To explore the inhibitory effect of verapamil, a calcium channel blocker, on the growth of human airway granulation fibroblasts to provide an experimental basis for the clinical use of calcium channel blockers in preventing and treating benign airway stenosis.
Primary human airway normal fibroblasts and human airway granulation fibroblasts were cultured by tissue block attachment culture method, and the experimental studies were carried out using 3-8 generation cells. Cell Counting Kit-8 (CCK-8) was used to test the proliferation of human normal airway fibroblasts and human airway granulation fibroblasts and the semi-inhibitory concentration of verapamil on normal airway fibroblasts and airway granulation fibroblasts. A scratch test detected the migration effect of verapamil on human airway granulation fibroblasts. The mRNA relative expression levels of related factors were detected by PCR to compare the differences between normal airway fibroblasts and airway granulation fibroblasts. Western blot was used to detect the relative amount of related proteins and compare the differences between normal airway fibroblasts and granulation airway fibroblasts. After 48 hours of treatment with half of the inhibitory concentration of Vera Pammy for granulation airway fibroblasts, the relative expression levels of related factors on mRNA and protein were observed.
Human normal airway fibroblasts and human airway granulation fibroblasts with a purity of more than 95% could be obtained from primary culture by tissue block adherence method. CCK8 results showed that the proliferation rate of human airway granulation fibroblasts was faster than that of the normal human airway fibroblasts. The semi-inhibitory concentration of verapamil on human normal airway fibroblasts was 92.81 ug/ml, while the semi-inhibitory concentration on human airway granulation fibroblasts was 69.57 ug/ml. The scratch test indicated that the cell migration rate of human airway granulation fibroblasts treated with verapamil decreased significantly (P < 0.05). PCR results showed that the mRNA relative expression levels of TGFβ1, COL1A1, Smad2/3, VEGFA, IL6, and IL8 in human airway granulation fibroblasts were significantly higher than those in normal human airway fibroblasts (P < 0.05). The mRNA relative expressions of TGFβ1, smad2/3, and COL1A1 in human airway granulation fibroblasts treated with semi-inhibited verapamil for 48h were down-regulated (P < 0.05), while the mRNA relative expressions of VEGFA, IL6 and IL8 had no significant changes (P > 0.05). WB test showed that the relative protein expressions of TGFβ1, Smad2, and VEGFC in human airway granulation fibroblasts were upregulated (P < 0.05) but downregulated after verapamil treatment compared with before treatment (P < 0.05).
Calcium channel blockers can inhibit the proliferation of human airway granulation fibroblasts through TGFβ1/ Smad pathway, which may be a method to prevent and treat benign airway stenosis.

BACKGROUND: Airway stent implantation used in the treatment of benign cicatricial airway stenosis (BCAS) can lead to local granulation and scar formation, resulting in restenosis and treatment failure.
METHODS: We systematically investigated a paclitaxel-loaded PLGA-coating stent (PLPCS) and analyzed the safety and efficacy of the PLPCS in patients with BCAS. Patients were enrolled from four hospitals in China and observed for six months after implantation, by bronchoscopy performed weekly in the first month and monthly thereafter. The stent was removed immediately upon detection of granulation tissue proliferation, leading to immobility of the stent.
RESULTS: Granulation tissue was formed one week after stent implantation, most of which was located at the upper edge of the stent and the narrowest airway in the stent. All stents were removed in three months (mean: 6.51 + 4.67 weeks), with a curative outcome in one case and ineffective results in two. The remaining seven patients developed complications within three months, necessitating early stent removal. The main complication was granulation formation, resulting in difficulty in stent removal.
CONCLUSIONS: Although PLPCS showed beneficial effects in basic and animal experiments, it cannot prevent airway restenosis in actual practice, mainly due to granulation formation.

Rigid tracheobronchoscopy (RTB) has seen an increasing interest over the last decades with the development of the field of IPM but no benchmark exists for complication rates in RTB. We aimed to establish benchmarks for complication rates in RTB.
A multicentric retrospective analysis of RTB performed between 2009 and 2015 in eight participating centres was performed.
A total of 1546 RTB were performed over the study period. One hundred and thirty-one non-lethal complications occurred in 103 procedures (6.7%, 95% CI: 5.5-8.0%). The periprocedural mortality rate was 1.2% (95% CI: 0.6-1.8%). The 30-day mortality rate was 5.6% (95% CI: 4.5-6.8%). Complication rate increases further when procedures were performed in an emergency setting. Procedures in patients with MAO are associated with a higher 30-day mortality (8.1% vs 2.7%, P < 0.01) and a different complication profile when compared to procedures performed for BAS.
RTB is associated with a 6.7% non-lethal complication rate, a 1.2% periprocedural mortality rate and a 5.6% 30-day mortality in a large multicentre cohort of patients with benign and malignant airway disease.

BACKGROUND: The use of self-expandable metallic stents (SEMS) in benign airway disease was the object of a boxed warning from the United States Food and Drug Administration in 2005 due to the risk of stent-related complications and difficulties associated with their removal. Third-generation fully covered SEMS have been commercialized since this warning and theoretically should not present the same difficulties associated with removal as they cannot become embedded in the airway mucosa.
OBJECTIVE: We aimed to examine the safety and efficacy of a specific third-generation SEMS, the Silmet stent.
METHODS: We reviewed the records of all patients treated for benign airway stenosis with third-generation Silmet SEMS from January 2011 to December 2015 at the North Hospital of Marseilles, France.
RESULTS: Forty SEMS were inserted in 30 patients over this period. Twenty (50.0%) stents were removed because of stent-related complications after a median of 77.0 ± 96.6 days (migration 32.5%, granulation tissue formation 7.5%, subjective intolerance 5.0%, mucus plugging 2.5%, laryngeal edema 2.5%). There were no cases of stent-related mortality. All complications were managed successfully endoscopically. Thirty-six stents (90.0%) were removed successfully after a median of 122.0 ± 113.2 days without any complications. The clinical success rate of stent treatment was 40.7%.
CONCLUSIONS: Third-generation SEMS are a safe treatment option for complex benign airway stenosis, but complications requiring stent removal are frequent. Further studies are needed to compare the performance of third-generation SEMS and silicone stents in benign airway stenosis.

Airway stents can provide effective and timely relief in patients with central airway obstruction. Silicone based stents are the most commonly used airway stents worldwide with a long track record of safety. Metallic stents continue to evolve from the earliest uncovered versions to a variety of newly designed covered stents. Despite the availability of a variety of stent materials and designs, minimal advances have been made towards innovation in stent technology and an ideal stent has unfortunately not yet been developed. Nevertheless, the first generation of biodegradable airway stents are available, work on drug-eluted stents is in the pipeline and three-dimensional printing of a customized airway stent may be the future. In this review, we discuss selection and results for most commonly utilized airway stents.