Tracheal Stenosis Research Articles

Unclassified bronchopulmonary foregut malformation in a 2-year-old girl

BackgroundBronchopulmonary foregut malformation (BPFM) is a rare congenital anomaly characterized by a fistula between an isolated portion of respiratory tissue and the esophagus or stomach. Srikanth et al. reported that BPFMs can be categorized into four groups, and that an unclassified BPFM is extremely rare. Herein, we present an unclassified BPFM group III and IV subtype in a 2-year-old girl.Case presentationAt a gestational age of 36 weeks, a 1535-g female neonate was born as one of the dichorionic diamniotic twins. She had vertebral abnormality, anovestibular fistula, pulmonary artery sling, small right lung, mediastinal shift with dextrocardia, tracheal stenosis, and radial hemimelia. After birth, she was diagnosed with VACTERL association. She exhibited consolidation of the right upper lobe (RUL) in the neonatal period; however, she had no respiratory symptoms and was kept under observation in an outpatient visit. At 24 months, she was urgently admitted with acute pneumonia, and the upper gastrointestinal series revealed the right upper bronchus arising from the lower esophagus. Therefore, she underwent RUL resection. Intraoperatively, the right lung had no lobulations. RUL was ventilated by the esophageal bronchus (BPFM group III); however, the S6 lesion was ventilated by both the normal bronchial system and esophageal bronchus (close to BPFM group IV). The S6 lesion did not satisfy the definition of group IV as it did not have systemic blood supply. Hence, we decided to preserve the S6 lesion to save lung capacity as much as possible. The esophageal bronchus was transected using a 5-mm stapler. Due to lobulation failure, RUL was resected using an electric scalpel and 5-mm staplers along with the demarcation line by ventilation from the normal bronchus. The postoperative course was uneventful, and the patient could regain oral function without pneumonia or respiratory distress.ConclusionsFor neonates with repeated consolidation and pneumonia, BPFM must be considered as one of the differential diagnoses. Regarding BPFM treatment, early recognition and imaging are necessary. To determine the resection area of the lung, it is crucial to consider the segment of ventilation from the normal bronchi.

Use of an autologous dermal flap and rib cartilage graft in the repair of a large tracheoesophageal fistula with tracheal stenosis.

Management of large tracheoesophageal fistulas complicated by tracheal stenosis remains challenging as it requires an ideal replacement for the membranous defect as well as a permanent buttress to reconstruct the stenotic segment. We present the successful use of an autologous free dermal flap reinforced with a pedicled pectoralis major muscle to repair the tracheal membranous wall and a rib cartilage graft to enlarge the tracheal lumen.

Distribution and chemotactic mechanism of CD4+ T cells in traumatic tracheal stenosis.

A systemic and local inflammatory immune imbalance is thought to be the cause of traumatic tracheal stenosis (TS). However, with CD4+ T lymphocytes being the predominant immune cells in TS, the mechanism of action and recruitment has not been described. In our research, using flow cytometry, ELISA, immunofluorescence, and Transwell chamber assays, the expression, distribution, and potential chemotactic function of CD4+ T cells in TS patients were examined before and after treatment. The results showed that the untreated group had significantly more CD4+ T cells and their secreted TGF-β1 than the treated group. Additionally, the untreated group's CD4+ T cells showed a significant rise in CCL22 and CCL1, as well as a larger proportion of CCR4 and CCR8. CD4+ T cells and CD68+ macrophages located in TS also expressed CCL1 and CCL22. In vitro, anti-CCL1 and anti-CCL22 can partially block the chemoattractant effect of TS bronchoalveolar lavage (BAL) on purified CD4+ T cells. The findings of this study indicated that TS contained unbalanced CD4 immune cells that were actively recruited locally by CCR4/CCL22 and CCR8/CCL1. As a result, it is anticipated that CD4 immune rebalancing can serve as a novel treatment for TS.

Spirometry in laryngotracheal stenosis: a systematic review and meta-analysis.

This study aimed to assess the changes in spirometry parameters or indices after relieving laryngotracheal stenosis (LTS) in adult patients. A systematic review and meta-analysis of studies from PubMed, Scopus, Web of Science, Cochrane Library, and EBSCO databases was conducted for assessing changes in spirometry values after endoscopic balloon dilatation of LTS in adults. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. Relevant data, such as changes in mean spirometry values between preoperative and postoperative interventions, and findings of receiver operating characteristic curve analyses for predicting the need for surgical intervention, were extracted. Ten studies including 330 patients overall met the inclusion criteria. Significant improvements were observed from preoperative to postoperative mean values of different spirometry parameters and indices. The overall mean differences in peak expiratory flow (ΔPEF), expiratory disproportion index (ΔEDI), and peak inspiratory flow (ΔPIF) were 2.26 L/s (95% CI 2.14-2.38), 27.94s (95% CI 26.36-29.52), and 1.21 L/s (95% CI 0.95-1.47), respectively. ΔPEF and ΔPIF values increased, while ΔEDI decreased. In predicting the need for surgical intervention, EDI had the highest sensitivity (88%), and forced expiratory volume per second/forced vital capacity had the highest specificity (85%). Spirometry is a valuable tool for assessing patients with LTS. PEF, EDI, and PIF were the most commonly reported spirometry parameters that significantly improved after airway stenosis was relieved.

GATA6 promotes fibrotic repair of tracheal injury through NLRP3 inflammasome-mediated epithelial pyroptosis

Tracheal injury is a challenging emergency condition that is characterized by the abnormal repair of the trachea. GATA6, a well-established transcription factor, plays a crucial role in tissue injury and epithelial regenerative repair. This study aims to evaluate the role of GATA6 in NF-κB-mediated NLRP3 inflammasome activation and pyroptosis after tracheal injury. Tracheal tissues and serum samples were collected from clinical patients and a rat model of tracheal injury. Upon GATA6 knockdown or overexpression, BEAS-2B and rat tracheal epithelial (RTE) cells were treated with lipopolysaccharides and nigericin before being co-cultured with primary tracheal fibroblasts. The changes of NLRP3 inflammasome activation and pyroptosis and their underlying mechanisms were detected. Additionally, the role of GATA6 downregulation in tracheal injury was verified in rats. GATA6 expression and NLRP3 inflammasome activation were upregulated following tracheal injury in the epithelium of granulation tissues. GATA6 silencing inhibited NLRP3 priming, NLRP3 inflammasome activation, and pyroptosis in BEAS-2B and RTE cells. Mechanistically, GATA6 was determined to have bound to the promoter region of NLRP3 and synergistically upregulated NLRP3 promoter activity with NF-κB. Furthermore, GATA6 overexpression promoted epithelial-mesenchymal transition via modulating the NF-κB/NLRP3 pathway. Epithelial NLRP3 inflammasome activation triggered ECM production in fibroblasts, which was suppressed by GATA6 knockdown and induced by GATA6 overexpression. Finally, the downregulation of GATA6 alleviated NLRP3 inflammasome-mediated pyroptosis induced by tracheal injury in rats, thereby reducing tracheal stenosis, inflammation, and fibrosis. GATA6 promotes fibrotic repair in tracheal injury through NLRP3 inflammasome-mediated epithelial pyroptosis, making it a potential biological therapeutic target for tracheal injury.

Predictors of Clinical Outcomes in Adult Laryngotracheal Stenosis.

Sequelae of laryngotracheal stenosis (LTS) can be devastating, often necessitating tracheostomy. This study aims to describe the characteristics and outcomes of patients with LTS and identify risk factors for long-term tracheostomy dependence stratified by etiology. A retrospective chart review was performed on 215 patients diagnosed with LTS from 09/01/2011 to 12/31/2020. Patients were grouped based on the cause of LTS. Patient factors were compared to evaluate risk factors for long-term tracheostomy dependence. Of the 215 patients, 129 (60%) were classified as iatrogenic, 41 (19%) idiopathic, 10 (4.7%) cancer treatment, 18 (8.3%) autoimmune, and 17 (8%) patients unknown. Idiopathic patients were significantly less likely to be tracheostomy-dependent compared with iatrogenic patients (p < 0.001) and cancer patients (p < 0.05). The mortality rate did not significantly differ among the categories (p = 0.1078). Significant improvement was seen after treatment, as the median percent of stenosis at presentation was 52.5%, and the median percent of stenosis at the most recent visit was 10% (p < 0.001). The autoimmune group received the most steroid injections (mean = 6.56; SD = 11.96). The idiopathic group had the longest surgery-free interval (mean = 30.8 months; SD = 27.7). Iatrogenic and cancer patients were more likely to be tracheostomy-dependent. There was a significant improvement in percent and length of stenosis after treatment, with the idiopathic group having the longest surgery-free interval. Mortality risk did not differ among the different etiologies of LTS. 3 Laryngoscope, 134:257-263, 2024.

Incidence of congenital tracheal stenosis in left pulmonary artery sling diagnosed by bronchoscopy.

Congenital tracheal stenosis (CTS) has been reported to occur in 50-65% of cases of left pulmonary artery sling (LPAS), but the exact incidence rate is unknown. This study aimed to determine the actual rate using bronchoscopy and to elucidate morphological features in computed tomography (CT) diagnosis. We performed a single institutional retrospective review of all patients with LPAS between January 2010 and March 2022. The percentage of complete tracheal rings in patients with LPAS was evaluated using bronchoscopy. The anteroposterior/lateral diameter ratios at the smallest and largest diameters of each CTS patient's trachea were measured on CT. The Wilcoxon signed-rank test was used to analyze the differences between the two parts. Fifty-two patients with LPAS were enrolled. All patients had complete tracheal rings on bronchoscopy. CT analysis of 32 patients with CTS was performed. The median anteroposterior/lateral diameter ratio at the smallest diameter was 1.05 (interquartile range [IQR] 0.95-1.15); the median ratio at the largest diameter was 0.94 (IQR 0.89-0.99). There was a significant difference between the two parts (p = 0.013). CTS might be universally associated with LPAS. The circular tracheal cross-section on CT might imply the existence of a complete tracheal ring.

Study to establish fiberoptic laryngoscopy as a diagnostic and investigation tool for laryngotracheal stenosis and to use the same for prognosis of the disease: retrospective analysis

Background: Laryngotracheal stenosis is a common benign condition of airway obstruction in both the pediatric and adult age group. This could either be acquired or congenital, in which there is narrowing of either the portions of the larynx or trachea making it difficult to breathe. This condition can be managed by several operative and endoscopic procedures. Flexible fiber optic laryngoscope is an excellent tool in the diagnostic investigation of laryngotracheal stenosis. Methods: This is a retrospective study that was done with data collected from the medical records department of patients diagnosed with laryngotracheal stenosis in a tertiary care hospital in the last 10 years. Results: A total of 22 patients who underwent FFL exam were taken for this retrospective study and the results were analyzed. Conclusions: This study proves that Fiberoptic laryngoscopy is a single modality diagnostic tool, which is useful in diagnosing, and localizing stenotic lesions in the Laryngotracheal region. It is cheap, less invasive and trained Otolaryngologist can perform this as an outpatient procedure. This therefore reduces the exposure to harmful radiation caused by repeated computed tomography scans.

Chronic respiratory disorders due to aberrant innominate artery: a case series and critical review of the literature

BackgroundTracheal compression (TC) due to vascular anomalies is an uncommon, but potentially serious cause of chronic respiratory disease in childhood. Vascular slings are congenital malformations resulting from abnormal development of the great vessels; in this group of disorders the most prevalent entity is the aberrant innominate artery (AIA). Here we provide a report on diagnosis and treatment of AIA in nine children with unexplained chronic respiratory symptoms. We describe the cases, perform a literature review, and provide a discussion on the diagnostic workup and treatment that can help manage AIA.MethodsClinical history, diagnostic procedures and treatment before and after the AIA diagnosis were retrospectively reviewed in nine children (5 boys and 4 girls), who were referred for recurrent-to-chronic respiratory manifestations over 10 years (2012–2022). We performed a comprehensive report on the ongoing clinical course and treatment as well as an electronic literature search on the topic.ResultsDiagnoses at referral, before AIA was identified, were chronic dry barking cough associated with recurrent pneumonia (n = 8, 89%), lobar/segmental atelectasis (n = 3, 33%), atopic/non atopic asthma (n = 3, 33%); pneumomediastinum with subcutaneous emphysema complicated the clinical course in one case. When referred to our Unit, all patients had been previously treated with repeated antibiotic courses (n = 9, 100%), alone (n = 6, 67%) or combined with prolonged antiasthma medications (n = 3, 33%) and/or daily chest physiotherapy (n = 2, 22%), but reported only partial clinical benefit. Median ages at symptom onset and at AIA diagnosis were 1.5 [0.08–13] and 6 [4–14] years, respectively, with a relevant delay in the definitive diagnosis (4.5 years). Tracheal stenosis at computed tomography (CT) was ≥ 51% in 4/9 cases and ≤ 50% in the remaining 5 subjects. Airway endoscopy was performed in 4 cases with CT evidence of tracheal stenosis ≥ 51% and confirmed CT findings. In these 4 cases, the decision of surgery was made based on endoscopy and CT findings combined with persistence of clinical symptoms despite medical treatment. The remaining 5 children were managed conservatively.ConclusionsTC caused by AIA may be responsible for unexplained chronic respiratory disease in childhood. Early diagnosis of AIA can decrease the use of expensive investigations or unsuccessful treatments, reduce disease morbidity, and accelerate the path toward a proper treatment.

Operative technique: Tracheal resection and anastomosis in a revision surgery.

Tracheal stenosis is an uncommon pathological condition in which the lumen of the trachea is reduced. Within its management an adequate preoperative workup is crucial to determine the most appropriate procedure for each patient. In this scenario tracheal resection and anastomosis is a viable approach, as a procedure in which part of the trachea is removed and then restored with a tension-free anastomosis. It is usually indicated for extensive and high-grade lesions or when previous endoscopic procedures had failed. The patient here presented had already undergone a balloon dilatation twice and a tracheal resection and referred to our clinic with a residual tracheal stenosis graded Myer-Cotton 3 involving three tracheal rings. We here illustrate step-by-step the surgical procedure and highlight a peculiar way to perform the anastomosis, especially in a revision surgery.

The attractiveness of 4D printing in the medical field: Revealing scientific and technological advances in design factors and applications

Currently, there is an increasing demand in the medical field for low-cost, high-quality products as well as personalized solutions, and different manufacturing methods are being investigated to provide innovative solutions. Four-dimensional (4D) printing is a promising technology that could overcome the challenges associated with the applications of three-dimensional printing in regenerative medicine and biomedical devices. A revolution is expected in this regard, and it is essential to keep abreast of the latest developments. Under this context, the purpose of this paper is to reveal scientific and technological advances of 4D printing in the medical field using a competitive technology intelligence (CTI) methodology. To this end, publications were analyzed from the Scopus database between January 1, 2017, and May 9, 2023. The main trends were identified for both design factors and applications. In the first case, the following were considered: 4D printing methods, external stimuli, materials, mathematical models, and interaction mechanisms. In contrast, in the second case, the applications of 4D printing involved were considered: drug delivery systems, stents, and scaffolds. The obtained design factors results included improvements in mechanical properties of hydrogels by adding magnetic nanoparticles, biopolyurethane, and other materials, the development of cell-friendly bioprinting methods to print cellular structures, and the use of theoretical-experimental approaches to predict shape deformation of structures. While for applications, results included advances in the development of expandable drug delivery systems, fabrication of stents for the treatment of vascular and tracheal stenosis, and the design of scaffolds to treat cartilage defects and bone regeneration. This study provides insights to researchers, academics, and companies involved in research and development as well as innovation that are looking for new solutions to improve health by incorporating breakthrough technologies such as 4D printing.

Surgical treatment of tracheal stenosis during Covid-19 era: a single-center experience and lessons learnt on the field

SARS-CoV2 outbreak led to several healthcare system challenges, especially concerning respiratory support to Covid-19 patients. In the first 2 years of pandemic (2020–2021), we assisted to a marked increase of post-invasive mechanical ventilation (IMV) tracheal stenosis incidence, many of them requiring surgical treatment, namely resection and primary end-to-end anastomosis. Our aim is to describe our experience during the abovementioned biennium, focusing on postoperative outcomes of patients who have had Covid-19 (“post-Covid”). We retrospectively collected pre-, intra- and postoperative data on all patients who underwent tracheal surgery for benign stenosis in our Unit from May 2020 to October 2021, including previous Covid-19. Comparison between “post-Covid-19” and “non-Covid-19” groups’ outcomes was then performed. Patients were 9 males and 6 females, and mean age was 57.4 ± 13.21 years. Nine patients had previous Covid-19 (60%). All patients underwent multidisciplinary preoperative evaluation. Almost every operation was conducted by cervicotomy, and the mean length of the resected specimen was 23.9 ± 6.5 mm. Postoperative complications were: dysphonia (3 cases), wound infection (1), bleeding (1), ab-ingestis pneumonia (1), anastomosis dehiscence (2), and stenosis recurrence (1). Thirty-day mortality rate was 6.7% (1 patient). No significant differences between “post-Covid-19” and “non-Covid-19” groups were identified. Pathology revealed, in 5 “post-Covid-19” patients, signs of vasculitis or perivascular inflammatory infiltrate. Tracheal stenosis’ surgical treatment has always been known as a challenging procedure because of high perioperative morbidity and mortality rates. Our experience shows that previous Covid-19 and ongoing pandemic did not significantly affect perioperative outcomes of patients who underwent tracheal resection and primary end-to-end anastomosis in a high-volume Center and after multidisciplinary workup.Graphical abstract

Profibrotic role of the SOX9–MMP10–ECM biosynthesis axis in the tracheal fibrosis after injury and repair

Fibroblast activation and extracellular matrix (ECM) deposition play an important role in the tracheal abnormal repair process and fibrosis. As a transcription factor, SOX9 is involved in fibroblast activation and ECM deposition. However, the mechanism of how SOX9 regulates fibrosis after tracheal injury remains unclear. We investigated the role of SOX9 in TGF-β1-induced fibroblast activation and ECM deposition in rat tracheal fibroblast (RTF) cells. SOX9 overexpression adenovirus (Ad-SOX9) and siRNA were transfected into RTF cells. We found that SOX9 expression was up-regulated in RTF cells treated with TGF-β1. SOX9 overexpression activated fibroblasts and promoted ECM deposition. Silencing SOX9 inhibited cell proliferation, migration, and ECM deposition, induced G2 arrest, and increased apoptosis in RTF cells. RNA-seq and chromatin immunoprecipitation sequencing (ChIP-seq) assays identified MMP10, a matrix metalloproteinase involved in ECM deposition, as a direct target of SOX9, which promotes ECM degradation by increasing MMP10 expression through the Wnt/β-catenin signaling pathway. Furthermore, in vivo, SOX9 knockdown ameliorated granulation proliferation and tracheal fibrosis, as manifested by reduced tracheal stenosis. In conclusion, our findings indicate that SOX9 can drive fibroblast activation, cell proliferation, and apoptosis resistance in tracheal fibrosis via the Wnt/β-catenin signaling pathway. The SOX9–MMP10–ECM biosynthesis axis plays an important role in tracheal injury and repair. Targeting SOX9 and its downstream target MMP10 may represent a promising therapeutic approach for tracheal fibrosis.

Nasal Septal Cartilage as Anterior Cap-Graft for Open Tracheoplasty in Cases for Laryngotracheal Stenosis: Our Initial Experience.

The aim of our study is to analyze the efficacy of nasal septal cartilage as cap-graft in laryngo-tracheoplasty in cases of Laryngotracheal stenosis. This was a prospective observational study carried out at a tertiary care hospital from March 2020 to March 2023. Total 8 patients who underwent laryngo-tracheoplasty using nasal septal cartilage as anterior Cap-graft were included in the study. Detailed history and clinical evaluation followed by diagnostic Flexible Fiber-optic Laryngoscopy and radiological investigations were done for all patients with post operative follow up for at least 1 year. Our study had maximum patients in age group of 11-30 years with male predominance, unknown compound ingestion being most common cause of intubation which was followed by tracheostomy. All patients had Cotton Mayer Grade III or IV subglottic stenosis. Out of 8 patients, 5 patients are decannulated, 1 patients still have T-tube in-situ whereas 2 patients didn't tolerate decannulation and required re-exploration. No donor site complication was seen during the study period. Nasal septal cartilage is a viable option for being used as anterior cap graft in laryngo-tracheoplasty. It can be a game changer, as can be done by E.N.T surgeon himself. No separate learning skills are required. It's cosmetically better with minimal complications; compared to life threatening complications like pneumothorax on using costal cartilage. Laryngeal framework is preserved as opposed to thyroid alar cartilage graft. Faster healing along with better postoperative donor site recovery are significant advantages.

Retracted: Clinical Application of Spiral CT Reconstruction Imaging in Patients with Tracheal Stenosis before Anesthesia.

[This retracts the article DOI: 10.1155/2022/9633527.].

Anterior mediastinal tracheostomy for severe tracheal stenosis in a child with severe motor and intellectual disabilities: a case report

BackgroundOwing to recurrent aspiration pneumonia and airway stenosis secondary to thoracic deformities, tracheostomy or laryngotracheal separation are often necessary in children with severe motor and intellectual disabilities. However, these procedures are associated with the risks of tracheal stenosis due to tracheal granulation and tracheoinnominate artery fistula formation. We report a case of a child with severe motor and intellectual disabilities treated with an anterior mediastinal tracheostomy.Case presentationThe patient was a 15-year-old boy with severe motor and intellectual disabilities due to intractable epilepsy. Due to thoracic deformity and tracheomalacia, the patient had a flattened and narrowed trachea. Accordingly, laryngotracheal separation was performed 4 months before admission to avoid aspiration pneumonia. Due to a common cold, the patient required frequent sputum suctioning, which exacerbated the tracheal stenosis. Bronchoscopy revealed tracheal stenosis 4–5 cm caudal to the tracheostomy site, tracheal mucosal ulcers, and pulsation of the innominate artery on the anterior wall of the trachea. We performed an anterior mediastinum tracheostomy to release the tracheal stenosis and prevent tracheoinnominate artery fistula formation.ConclusionsAnterior mediastinal tracheostomy has several advantages. Including sufficient release of bony compression, release of tracheal hyperextension, and relief of tracheal and innominate artery contact ensures a cannula-free tracheostomy, and there is no need to dissect the brachiocephalic artery. It is the procedure of choice in cases of head and neck malignancies requiring extensive tracheal resection and could be a good surgical option for severe tracheal stenosis and tracheoinnominate artery fistula in children with severe motor and intellectual disabilities.

Anesthesia for laryngotracheal reconstruction in children: Anarrative review.

Laryngotracheal stenosis, congenital or acquired, is a common cause of pediatric airway obstruction. Acquired subglottic stenosis frequently results from prolonged neonatal intubation. The clinical presentation of subglottic stenosis is variable, ranging from biphasic stridor and frequent upper respiratory infections to acute airway compromise. Optimal patient care requires clinical coordination within a multidisciplinary subspecialty team. Medical management includes optimizing respiratory status, gastroesophageal reflux, speech, feeding, nutrition therapies, and providing psychosocial support. If surgical intervention is required, the otolaryngologist, anesthesiologist, and perioperative team must collaborate closely to ensure successful operative outcomes. This narrative review of laryngotracheal stenosis will discuss the pathophysiology, clinical evaluation, medical management, and surgical interventions, and focus on the perioperative anesthetic considerations for children undergoing laryngotracheal reconstruction.

Numerical simulation of the effect of geometric parameters on silicone airway stent migration

Recently, endotracheal stenting has become critical in treating respiratory diseases. Due to the COVID-19 pandemic in recent years, many patients had stenosis because of long-term intubation, and silicone stents can be used to treat tracheal stenosis in these patients. Standard airway stents are silicone tubes that provide immediate relief but are prone to migration. In this work, we design different silicone stents and analyze them in the trachea to evaluate silicone airway stents’ performance to overcome undesired migration. A finite-element model of the trachea was employed to evaluate anti-migration forces in each stent. The geometry of the trachea is brought from a computerized tomography scan of the chest of a 68-year-old healthy man. The results are shown based on the least migration of stents based on anti-migration forces. Also, the conditions of stent placement have been considered based on two different assumed friction factors, and the importance of choosing the type of silicone for stent construction has been analyzed. The results show that increasing the diameter of the stent reduces the displacement and migration of it in the trachea. Furthermore, the 23 mm stent with a 45° angle revealed the best implementation against compression under the impact of respiratory pressure differences.

Inhalation of Carboxymethyl Chitosan Alleviates Posttraumatic Tracheal Fibrosis.

The present study was performed to determine whether the inhalation of carboxymethyl (CM)-chitosan can alleviate tracheal fibrosis in a rabbit model. We designed a rabbit model of tracheal stenosis involving electrocoagulation with a spherical electrode. Twenty New Zealand white rabbits were randomly divided into experimental and control groups (10 animals each). Tracheal damage was successfully established by electrocoagulation in all animals. The experimental group was given CM-chitosan (inhalation for 28 days), while the control group inhaled saline. The effects of CM-chitosan inhalation on tracheal fibrosis were analyzed. Laryngoscopy was performed to evaluate and grade tracheal granulation, while tracheal fibrosis was evaluated by histological examination. The effects of CM-chitosan inhalation on the tracheal mucosa were examined by scanning electron microscopy (SEM), and hydroxyproline content in tracheal scar tissue was determined by enzyme-linked immunosorbent assay (ELISA). Laryngoscopy showed that the tracheal cross-sectional area was smaller in the experimental than control group. The amounts of loose connective tissue and damaged cartilage, as well as the severity of collagen and fibrosis, decreased following inhalation of CM-chitosan. According to the ELISA, the experimental group had low levels of hydroxyproline in the tracheal scar tissue. The findings presented here showed that inhalation of CM-chitosan mitigated posttraumatic tracheal fibrosis in a rabbit model, thus suggesting a potential new treatment for tracheal stenosis.

Use of Mitomycin-C in Laryngotracheal Stenosis: A Focused Clinical Review.

Therapeutic options for managing laryngotracheal stenosis (LTS) are limited. Endoscopy is a minimally invasive approach to treating LTS, but carries a high risk of stenosis recurrence. Mitomycin C (MMC) is often used as an adjunct therapy to delay the time to symptomatic recurrence of LTS. This review synthesizes the current literature on the topic of MMC as an adjunct treatment strategy for LTS. A focused literature search was carried out from PubMed on June 12, 2022 using the terms "mitomycin c AND stenosis" in all fields with no date limitations. Evidence-based recommendations relevant to the clinical application of MMC as an adjunct therapy for LTS were formulated. Three questions were addressed: 1) efficacy of MMC, 2) single versus multiple application(s) of MMC, and 3) safety of MMC. The evidence rating and recommendation strength were guided by the GRADE system. Twenty-nine studies were reviewed. The efficacy of MMC as an adjunct therapy for LTS varied across studies. Randomized controlled trials have not shown an outcome difference with MMC use, although methodologic flaws including underpowering were noted. A meta-analysis of observational studies with a comparator arm found the unadjusted probability of remaining symptom-free for >1 year is greater with versus without MMC application (73% vs. 35%). Single versus multiple application(s) of MMC resulted in similar restenosis rates at long-term follow-up. Complications related to MMC use are rarely reported using conventional doses (0.4mg/mL). Overall, the quality of evidence was low and the recommendation for intervention was weak. The role for MMC as an adjunct therapy in LTS is uncertain. While safe in its application, the efficacy of MMC in reducing stenosis recurrence remains a matter of debate. Large, prospective studies are needed to inform future recommendations.