Complication of silicone stent in the management of airway stenosis: a single-center experience

Introduction

Central airway stenosis is defined as an abnormal narrowing of the tracheal or bronchial lumen that can cause significant respiratory symptoms and even compromise the patient’s life (1). For objective decision-making purposes, it is divided according to histological origin into benign and malignant (2,3). Lung cancer accounts for 60% to 70% of malignant cases (4), but may occur alongside other malignant neoplasms. Post-intubation and post-tracheostomy tracheal stenosis are the leading causes of benign stenosis (5).

Clinically, it could manifest with progressive dyspnea, stridor, chronic cough, wheezing, and even respiratory failure, symptoms that are often confused with more common diseases such as asthma or chronic obstructive pulmonary disease (6).

Management of the stenosis depends on its etiology, extent, and severity. Surgical resection with end-to end anastomosis is the chosen treatment in complex benign stenosis; however, not all patients are candidates due to the length of the lesion, comorbidities or associated clinical conditions (7). Under these circumstances, the placement of silicone stent in the airway has emerged as a valid alternative treatment, providing luminal patency and symptomatic improvement. Nonetheless, as these are foreign bodies, these airway stents are associated with multiple complications: migration, granulation tissue formation, mucus plugging, local infections, or injuries during the procedure (3,7,8). Internationally, several studies have documented silicone stent experience, highlighting variable complication rates and heterogeneous results based on the population and type of device (9-15).

Although rigid bronchoscopy remains the gold standard for the diagnosis and treatment of stenosis, chest computed tomography (CT) plays a complementary role in the diagnosis and follow-up of patients with stenosis and stent. A sensitivity of 88% and a specificity of 100% (16) have been found in the detection and follow-up of complications, and CT is a noninvasive tool that could improve patient surveillance (17,18).

Rationale and knowledge gap

Despite the increasing use of silicone stents in Mexico and Latin America, there is limited published institutional evidence describing complication patterns, associated clinical and technical characteristics, and imaging correlations. No national series has comprehensively evaluated silicone stent performance using combined clinical, bronchoscopic, and tomographic data. Establishing local evidence is essential for improving surveillance protocols, recognizing early predictors of instability, and optimizing decision-making in centers managing complex airway stenosis.

Objective

The objective of this study is to describe the institutional experience in the management of airway stenosis with silicone stents at a national reference center, focusing on the complications observed, the clinical and technical characteristics of affected patients, and the corresponding tomographic findings. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1-2523/rc).

Methods

Study design and setting

We conducted an observational, descriptive, retrospective study at the National Institute of Respiratory Diseases in Mexico City, a national reference center for pulmonary pathology and interventional bronchoscopy. The study period extended from January 2019 to January 2025.

Study population

We included adult patients (≥18 years) of both sexes diagnosed with subglottic or central airway stenosis who underwent silicone stent placement using rigid bronchoscopy performed by the Interventional Bronchoscopy Service.

Inclusion criteria

• Diagnosis of subglottic or central airway stenosis;
• Silicone stent placement performed at the National Institute of Respiratory Diseases;
• At least one stent-related complication during follow-up;
• Complete clinical information, bronchoscopy reports, and chest CT are available in the medical record.

Exclusion criteria

• Pediatric patients;
• Patients treated with metallic stents or devices made of materials other than silicone;
• Incomplete clinical or radiological information.

The study size corresponded to all eligible patients who underwent silicone stent placement at the institution during the study period. No formal sample size calculation was performed due to the descriptive nature of the study.

Clinical, demographic, and technical variables

The following demographic and clinical variables were recorded: age, sex, body mass index (BMI), comorbidities (diabetes mellitus, hypertension, chronic kidney disease), smoking history, systemic corticosteroid use, history of tracheostomy, etiology of stenosis (post-intubation, infectious, autoimmune, malignant), anatomical location (subglottic, tracheal, tracheobronchial, or bronchial), and degree of obstruction according to Cotton’s classification.

Technical variables included: type and diameter of the silicone stent, number of airway dilations prior to placement, number of bronchoscopic revisions, total number of stent replacements, and whether the procedure was performed electively or emergently.

For the purpose of this study, complex airway stenosis was defined as a stenosis involving a length greater than 1 cm, the presence of significant cartilaginous involvement or airway Malacia, irregular or multifocal narrowing, or stenosis requiring repeated endoscopic interventions prior to stent placement.

Definition and classification of complications

Complications were defined as any adverse event related to the stent or procedure that required:

• Bronchoscopic intervention;
• Stent replacement;
• Specific therapeutic management.

The following complication categories were analyzed:

• Granulation tissue formation;
• Stent migration;
• Mucus plugging;
• Infection;
• Airway injury.

Bias

To minimize selection bias, consecutive adult patients who underwent silicone stent placement during the study period and met the inclusion criteria were included. Information bias was reduced by obtaining data from standardized bronchoscopy reports and institutional electronic medical records.

Not all patients had available CT studies during follow-up. Available CT scans corresponding to acute or urgent clinical events were systematically reviewed, and the tomographic findings were compared with bronchoscopy reports performed on concordant dates. In addition, CT studies obtained during scheduled follow-up and not associated with acute clinical events were also reviewed. All CT images were evaluated through direct visualization by a pulmonologist with expertise in airway disease, and findings were correlated with the available bronchoscopic information.

Tomographic evaluation

Chest CT scans obtained during scheduled follow-up or acute clinical events were reviewed. CT findings of interest included:

• Stent migration;
• Obstructive mucus plugging;
• Pneumomediastinum;
• Air pockets between the stent and the airway wall.

CT findings were compared with the same-episode bronchoscopy reports to determine concordance.

Statistical analysis

Descriptive statistics were used. Quantitative variables were expressed as medians and interquartile ranges (IQRs), while qualitative variables were expressed as absolute frequencies and percentages. Data collection and analysis were performed using Stata version 18.0 (StataCorp, College Station, TX, USA).

Missing data were reported when present. No imputation was performed.

Ethical considerations

This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics and Research Committee of the National Institute of Respiratory Diseases, Mexico City (C60-22). All imaging and bronchoscopic material included was original and obtained from the National Institute of Respiratory Diseases (INER), Mexico City. Written informed consent was obtained from all patients or their legal representatives for the use of clinical information and images for research and publication purposes. Patient confidentiality and anonymity were ensured throughout.

Results

Patient characteristics

A total of 23 patients met the inclusion criteria. The median age was 42 years (IQR, 34–53 years), and 60.9% were women. The mean BMI was 26.8 kg/m². The most frequent comorbidities were systemic arterial hypertension (13.0%), obesity (30.4%), and type 2 diabetes mellitus (17.4%). Four patients (17.4%) had a smoking history, and none had a prior diagnosis of asthma or chronic obstructive pulmonary disease.

A history of tracheostomy was present in 21.7% of cases, and systemic steroid use before stent placement occurred in 39.1% (Table 1).

Etiology and anatomical distribution of stenosis

Post-intubation stenosis was the most common etiology (52.2%), followed by autoimmune causes (30.4%). Autoimmune-related airway stenosis was identified in seven patients. Six patients had a diagnosis of granulomatosis with polyangiitis, and one patient had relapsing polychondritis, malignant disease (13.0%), and infectious causes (4.4%). Among post-intubation cases, trauma was the most frequent indication for endotracheal intubation (66.7%), with a median intubation duration of 14 days (IQR, 8–16 days).

Most stenoses were classified as complex (95.6%) and were primarily located in the trachea (61%), followed by subglottic (13%), tracheobronchial (13%), and bronchial regions (13%) (Figure 1).

Figure 1 Anatomical sites of stenosis and stent placement. Schematic representation of the tracheobronchial tree illustrating the distribution of stenotic sites among patients: tracheal (60%), subglottic (13%), and tracheobronchial locations (13%). Complex stenosis (>1 cm, cartilage involvement, or multiple stenotic segments) was present in 95.6% of cases. The symbols represent the corresponding anatomical locations for each stenosis type.

Technical characteristics and bronchoscopic follow-up

According to Cotton’s classification, 82.6% of patients had grade IV stenosis. Most patients required 1–3 dilations before stent placement (77.3%). In 60.9% of cases, stents with a diameter ≥14 mm were used.

During follow-up, 216 bronchoscopies were performed, with a median of 7 revisions per patient (IQR, 4–17 revisions per patient). Of these, a median of 5 revisions (IQR, 2–18 revisions) were related to complications. The median number of stent replacements was 2 per patient (IQR, 1–3 per patient). No deaths were attributed to stent-related complications (Table 2).

Complications related to silicone stents

A total of 171 complications were recorded.

• Granulation tissue formation was the most frequent complication: 70 events affecting 78.3% of patients, with a median onset of 61 days (IQR, 21–127 days). This event predominated in autoimmune and post-intubation etiologies.
• Mucus plugging occurred in 73.9% of patients (66 events), with a median onset of 53 days (IQR, 28–105 days).
• Stent migration affected 47.8% of patients (30 events), occurring at a median of 49 days (IQR, 18–138 days). Post-intubation stenosis showed the highest migration frequency.
• Airway injuries were identified in 4 patients (17.4%), particularly in those with malignant stenosis or mucormycosis, where the stent served both therapeutic and structural functions.
• Infection occurred in 1 patient (4.3%), associated with Staphylococcus aureus infection 12 days after placement.
• The patient with mucormycosis exhibited the highest number of adverse events (22 episodes), primarily granulation (Table 3).

Tomographic findings and endoscopic correlation

A total of 124 chest CT scans were reviewed: 39.5% were obtained due to acute symptoms and 60.5% during scheduled follow-up.

CT demonstrated:

• Stent migration in 42.1% of evaluations with complications (Figure 2);
• Mucus plugging in 21.0%.

Figure 2 CT findings during acute events. Axial CT images illustrating the main complications identified during acute presentations. (A) Mucus plugging. (B-D) Different patterns of silicone stent migration, including distal displacement and proximal dislodgement. Findings observed on bronchoscopy were consistent with those identified on CT in all event-driven evaluations. CT, computed tomography.

CT findings were concordant with bronchoscopic findings in all event-driven evaluations.

Two cases of pneumomediastinum were documented in the context of airway injury (Figure 3).

Figure 3 CT and bronchoscopic correlates of airway injury. Axial CT images from a patient with tracheal stenosis who underwent rigid bronchoscopy and dilation prior to planned silicone stent placement. During the procedure, an airway injury occurred. (A) Disruption of the tracheal wall (red arrow) with pneumomediastinum and subcutaneous emphysema. (B) Area of tracheal stenosis. (C) Tracheal stent placement (orange arrow) restores the airway lumen and simultaneously provides structural support for the previous injury. CT, computed tomography.

Additionally, air pockets between the stent and airway wall were identified in five clinically stable patients, all of whom later developed migration.

Overall, post-intubation stenosis was associated with the highest rates of migration and mucus plugging, whereas autoimmune stenosis showed a greater tendency toward granulation tissue formation. Malignant and infectious etiologies demonstrated fewer cases but more severe complications, including airway injury.

Discussion

This study describes the clinical, technical, and imaging characteristics of patients who developed complications after silicone airway stent placement at a national referral center. Given the retrospective design and the inclusion of only patients with at least one stent-related adverse event, this analysis was not intended to estimate the overall incidence of complications nor to evaluate diagnostic test performance. Instead, the objective was to characterize patient profiles, complication patterns, their timing, and the associated bronchoscopic and tomographic findings among complicated cases.

Given the complexity of each individual case, we focused on detailed characterization of patient features and the follow-up strategies applied during the time the central airway stent was in place. Both emergency evaluations and scheduled follow-up assessments were reviewed, including chest CT studies obtained during acute events and routine surveillance.

Previous evidence regarding the efficacy and safety of airway stents has shown relevant complication rates. A meta-analysis reported migration rates of approximately 23.04%, while mucus retention occurred more frequently (25.82%) than reported in earlier series. Silicone stent-related complications are more commonly described in patients with benign tracheal stenosis (19-22).

The high frequency of complications observed in our cohort may be explained by the predominance of benign etiologies, particularly post-intubation stenosis in the context of the coronavirus disease 2019 (COVID-19) pandemic, as well as by the complexity of the stenoses treated. Furthermore, the retrospective design combined with rigorous bronchoscopic surveillance likely increased the detection of complications. Importantly, most complications were identified during scheduled, non-emergency procedures in patients who were asymptomatic or had mild symptoms.

Regarding complication severity, urgent bronchoscopies reported in Table 2 were considered markers of severe stent-related complications. These events were associated with acute respiratory compromise requiring emergency department evaluation and immediate bronchoscopic intervention. Given the sample size and retrospective follow-up, complications were pragmatically classified as severe when they required emergency department assessment and urgent bronchoscopic management. In contrast, complications identified during scheduled follow-up that did not require immediate intervention were considered non-severe findings and represented the majority of observed events.

We believe that this distribution of severe and non-severe complications may be related to the strict clinical and bronchoscopic follow-up applied in our cohort. Patients were monitored closely and at relatively short intervals, allowing early detection of stent-related findings during scheduled imaging studies and planned bronchoscopic evaluations. The identification of complications as imaging or endoscopic findings before the development of acute respiratory compromise may have contributed to preventing progression to severe events requiring emergency intervention. This observation underscores the importance of implementing a structured and proactive follow-up strategy in patients with airway stents.

There is currently no universal consensus regarding the optimal timing of follow-up after silicone stent placement. While the World Association for Bronchology and Interventional Pulmonology (WABIP) guidelines suggest routine surveillance bronchoscopy at approximately 4–6 weeks following stent insertion, follow-up strategies may vary according to institutional practice and clinical context. At our center, earlier bronchoscopic evaluation is often performed based on symptom development, procedural complexity, and perceived risk of complications. In this setting, chest CT may serve as a complementary, non-invasive tool to guide the timing and urgency of bronchoscopic reassessment (7).

When complication patterns were examined according to complication type and airway location, distinct trends were observed. Mucus plugging and granulation tissue formation were the most frequent events, predominantly occurring in tracheal and main bronchial stents, likely reflecting impaired mucociliary clearance and chronic airway irritation related to the presence of a foreign body.

Stent migration was observed across different anatomical locations but appeared more commonly in complex or longer stenoses and in cases with dynamic airway changes over time. In this cohort, migration represented a heterogeneous phenomenon influenced not only by mechanical factors such as stent-airway mismatch, but also by changes in the underlying airway condition during follow-up.

Although subglottic stents represented a smaller proportion of cases, this location warrants particular attention due to its proximity to the vocal cords and the associated risk of voice alteration and aspiration. While formal stratified analysis by stenotic site was not feasible given the sample size, these descriptive observations emphasize the need for individualized surveillance strategies based on both complication type and airway anatomy.

In this series, chest CT findings were concordant with bronchoscopic findings in all event-driven evaluations. It is important to emphasize that most CT examinations were performed in the context of acute symptoms or clinical suspicion of complications rather than as a systematic screening tool. Therefore, the observed concordance reflects agreement under selected clinical conditions and should not be interpreted as a measure of diagnostic accuracy, sensitivity, or specificity. Bronchoscopy remains the gold standard for the evaluation and management of airway stent-related complications.

One of the strengths of this study is that it represents the first institutional series in Mexico to systematically integrate clinical experience with imaging findings related to silicone airway stent complications. To our knowledge, no similar studies have been reported in Mexico or Latin America. This reinforces the relevance of the National Institute of Respiratory Diseases as a national referral center managing a high volume of complex airway cases.

Nonetheless, several limitations must be acknowledged, including the retrospective design, single-center experience, small sample size, and absence of a comparative group. Despite these limitations, our findings highlight the importance of structured surveillance protocols and support the need for multicenter studies to establish more robust follow-up strategies for patients with airway stents.

Conclusions

In this institutional series of patients who developed complications after silicone airway stent placement, adverse events occurred predominantly early during follow-up, with granulation tissue formation, mucus plugging, and migration being the most frequently observed findings. Chest CT showed high agreement with bronchoscopy in clinically indicated evaluations and may represent a useful complementary tool for assessing stent-related complications, without replacing endoscopic assessment. Radiologic findings such as air pockets should be interpreted cautiously and considered hypothesis-generating. Given the retrospective design, selection bias, and limited sample size, these findings highlight the need for structured surveillance strategies and prospective multicenter studies to better define risk stratification and follow-up protocols for patients undergoing silicone airway stenting.

Acknowledgments

The authors would like to thank the staff of the Interventional Pulmonology Program at the National Institute of Respiratory Diseases for their support during data collection and patient follow-up throughout the study period.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1-2523/rc

Data Sharing Statement: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1-2523/dss

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1-2523/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1-2523/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics and Research Committee of the National Institute of Respiratory Diseases, Mexico City (C60-22). Written informed consent was obtained from all patients or their legal representatives for the use of clinical and imaging information for research and publication purposes. Patient confidentiality and anonymity were strictly maintained.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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